plotly · waralex · May 22, 2020 · May 5, 2020 · May 15, 2020 · May 17, 2020
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -3,6 +3,7 @@ All notable changes to this project will be documented in this file. This projec
 
 ### [UNRELEASED]
 ### Added
+- Support for hot reloading on application or asset changes [#25](plotly/Dash.jl#25)
 - Asset serving of CSS, JavaScript, and other resources [#18](plotly/Dash.jl#18)
 - Support for passing functions as layouts [#18](plotly/Dash.jl#18)
 - Resource registry for component assets [#18](plotly/Dash.jl#18)

diff --git a/Project.toml b/Project.toml
@@ -13,7 +13,9 @@ LibGit2 = "76f85450-5226-5b5a-8eaa-529ad045b433"
 MD5 = "6ac74813-4b46-53a4-afec-0b5dc9d7885c"
 MacroTools = "1914dd2f-81c6-5fcd-8719-6d5c9610ff09"
 PlotlyBase = "a03496cd-edff-5a9b-9e67-9cda94a718b5"
+Sockets = "6462fe0b-24de-5631-8697-dd941f90decc"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
+UUIDs = "cf7118a7-6976-5b1a-9a39-7adc72f591a4"
 
 [compat]
 DataStructures = "0.17.5"

diff --git a/README.md b/README.md
@@ -21,7 +21,7 @@ import Pkg; Pkg.add(Pkg.PackageSpec(url = "https://github.com/plotly/Dash.jl.git
 
 ```jldoctest
 julia> using Dash
-julia> app = dash("Test app", external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"])
+julia> app = dash(external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"])
 
 julia> app.layout = html_div() do
  html_h1("Hello Dash"),
@@ -55,7 +55,7 @@ __Once you have run the code to create the Dashboard, go to `http://127.0.0.1:80
 ```jldoctest
 
 julia> using Dash
-julia> app = dash("Test app", external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"])
+julia> app = dash(external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"])
 
 julia> app.layout = html_div() do
  dcc_input(id = "my-id", value="initial value", type = "text"),
@@ -76,7 +76,7 @@ julia> run_server(app, "0.0.0.0", 8080)
 ### States and Multiple Outputs
 ```jldoctest
 julia> using Dash
-julia> app = dash("Test app", external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"])
+julia> app = dash(external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"])
 
 julia> app.layout = html_div() do
  dcc_input(id = "my-id", value="initial value", type = "text"),

diff --git a/docs/src/index.md b/docs/src/index.md
@@ -33,7 +33,7 @@ import Pkg; Pkg.add("Dashboards")
 ```jldoctest
 julia> import HTTP
 julia> using Dashboards
-julia> app = Dash("Test app", external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
+julia> app = Dash(external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
  html_div() do
  html_h1("Hello Dashboards"),
  html_div("Dashboards: Julia interface for Dash"),
@@ -68,7 +68,7 @@ __Once you have run the code to create the Dashboard, go to `http://127.0.0.1:80
 ```jldoctest
 julia> import HTTP
 julia> using Dashboards
-julia> app = Dash("Test app", external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
+julia> app = Dash(external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
  html_div() do
  dcc_input(id = "my-id", value="initial value", type = "text"),
  html_div(id = "my-div") 
@@ -89,7 +89,7 @@ julia> HTTP.serve(handler, HTTP.Sockets.localhost, 8080)
 ```jldoctest
 julia> import HTTP
 julia> using Dashboards
-julia> app = Dash("Test app", external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
+julia> app = Dash(external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
  html_div() do
  dcc_input(id = "my-id", value="initial value", type = "text"),
  html_div(id = "my-div"),

diff --git a/src/Dash.jl b/src/Dash.jl
@@ -1,5 +1,6 @@
 module Dash
 import HTTP, JSON2, CodecZlib, MD5
+using Sockets
 using MacroTools
 const ROOT_PATH = realpath(joinpath(@__DIR__, ".."))
 include("Components.jl")
@@ -19,7 +20,6 @@ include("utils.jl")
 include("app.jl")
 include("resources/registry.jl")
 include("resources/application.jl")
-include("config.jl")
 include("handlers.jl")
 
 @doc """
@@ -31,7 +31,7 @@ Julia backend for [Plotly Dash](https://github.com/plotly/dash)
 ```julia
 
 using Dash
-app = dash("Test", external_stylesheets=["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
+app = dash(external_stylesheets=["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
  html_div() do
  dcc_input(id="graphTitle", value="Let's Dance!", type = "text"),
  html_div(id="outputID"), 
@@ -76,7 +76,7 @@ Run Dash server
 
 #Examples
 ```jldoctest
-julia> app = dash("Test") do
+julia> app = dash() do
  html_div() do
  html_h1("Test Dashboard")
  end
@@ -111,10 +111,53 @@ function run_server(app::DashApp, host = HTTP.Sockets.localhost, port = 8050;
  dev_tools_silence_routes_logging = dev_tools_silence_routes_logging,
  dev_tools_prune_errors = dev_tools_prune_errors
  )
- handler = make_handler(app);
- @info string("Running on http://", host, ":", port)
- HTTP.serve(handler, host, port)
-end
+ main_func = () -> begin
+ ccall(:jl_exit_on_sigint, Cvoid, (Cint,), 0)
+ handler = make_handler(app);
+ try
+ task = @async HTTP.serve(handler, host, port)
+ @info string("Running on http://", host, ":", port)
+ wait(task)
+ catch e
+ if e isa InterruptException
+ @info "exited"
+ else
+ rethrow(e)
+ end
+
+ end
+ end
+ start_server = () -> begin
+ handler = make_handler(app);
+ server = Sockets.listen(get_inetaddr(host, port))
+ task = @async HTTP.serve(handler, host, port; server = server)
+ @info string("Running on http://", host, ":", port)
+ return (server, task)
+ end
 
+ if get_devsetting(app, :hot_reload) && !is_hot_restart_available()
+ @warn "Hot reloading is disabled for interactive sessions. Please run your app using julia from the command line to take advantage of this feature."
+ end
+
+ if get_devsetting(app, :hot_reload) && is_hot_restart_available()
+ hot_restart(start_server, check_interval = get_devsetting(app, :hot_reload_watch_interval))
+ else
+ (server, task) = start_server()
+ try
+ wait(task)
+ println(task)
+ catch e
+ close(server)
+ if e isa InterruptException 
+ println("finished")
+ return
+ else
+ rethrow(e)
+ end
+ end
+ end
+end
+get_inetaddr(host::String, port::Integer) = Sockets.InetAddr(parse(IPAddr, host), port)
+get_inetaddr(host::IPAddr, port::Integer) = Sockets.InetAddr(host, port)
 
 end # module
diff --git a/src/app/callbacks.jl b/src/app/callbacks.jl
@@ -19,7 +19,7 @@ Create a callback that updates the output by calling function `func`.
 # Examples
 
 ```julia
-app = dash("Test") do
+app = dash() do
  html_div() do
  dcc_input(id="graphTitle", value="Let's Dance!", type = "text"),
  dcc_input(id="graphTitle2", value="Let's Dance!", type = "text"),

diff --git a/src/app/dashapp.jl b/src/app/dashapp.jl
@@ -25,14 +25,16 @@ Dash.jl's internal representation of a Dash application.
 This `struct` is not intended to be called directly; developers should create their Dash application using the `dash` function instead.
 """
 mutable struct DashApp
- name ::String
+ root_path ::String
+ is_interactive ::Bool
  config ::DashConfig
  index_string ::Union{String, Nothing}
+ title ::String
  layout ::Union{Nothing, Component, Function}
  devtools ::DevTools
  callbacks ::Dict{Symbol, Callback}
 
- DashApp(name, config, index_string) = new(name, config, index_string, nothing, DevTools(dash_env(Bool, "debug", false)), Dict{Symbol, Callback}())
+ DashApp(root_path, is_interactive, config, index_string, title = "Dash") = new(root_path, is_interactive, config, index_string, title, nothing, DevTools(dash_env(Bool, "debug", false)), Dict{Symbol, Callback}())
 
 end
 
@@ -41,6 +43,7 @@ function Base.setproperty!(app::DashApp, property::Symbol, value)
  property == :name && return set_name!(app, value)
  property == :index_string && return set_index_string!(app, value)
  property == :layout && return set_layout!(app::DashApp, value)
+ property == :title && return set_title!(app::DashApp, value)
 
  property in fieldnames(DashApp) && error("The property `$(property)` of `DashApp` is read-only")
 
@@ -51,6 +54,10 @@ function set_name!(app::DashApp, name)
  setfield!(app, :name, name)
 end
 
+function set_title!(app::DashApp, title)
+ setfield!(app, :title, title)
+end
+
 get_name(app::DashApp) = app.name
 
 function set_layout!(app::DashApp, component::Union{Component,Function})
@@ -106,6 +113,8 @@ get_devsetting(app::DashApp, name::Symbol) = getproperty(app.devtools, name)
 
 get_setting(app::DashApp, name::Symbol) = getproperty(app.config, name)
 
+get_assets_path(app::DashApp) = joinpath(app.root_path, get_setting(app, :assets_folder))
+
 """
  dash(name::String;
  external_stylesheets,
@@ -134,7 +143,6 @@ If a parameter can be set by an environment variable, that is listed as:
  Values provided here take precedence over environment variables.
 
 # Arguments
-- `name::String` - The name of your application
 - `assets_folder::String` - a path, relative to the current working directory,
  for extra files to be used in the browser. Default `'assets'`. All .js and .css files will be loaded immediately unless excluded by `assets_ignore`, and other files such as images will be served if requested.
 
@@ -212,7 +220,7 @@ If a parameter can be set by an environment variable, that is listed as:
  files and data served by HTTP.jl when supported by the client. Set to
  ``false`` to disable compression completely.
 """
-function dash(name::String = dash_env("dash_name", "");
+function dash(;
  external_stylesheets = ExternalSrcType[],
  external_scripts = ExternalSrcType[],
  url_base_pathname = dash_env("url_base_pathname"), 
@@ -242,7 +250,7 @@ function dash(name::String = dash_env("dash_name", "");
  requests_pathname_prefix,
  routes_pathname_prefix
  )...,
-absolute_assets_path(assets_folder),
+ assets_folder,
  lstrip(assets_url_path, '/'),
  assets_ignore, 
  serve_locally, 
@@ -254,6 +262,6 @@ function dash(name::String = dash_env("dash_name", "");
  show_undo_redo,
  compress
  )
- result = DashApp(name, config, index_string)
+ result = DashApp(app_root_path(), isinteractive(), config, index_string)
  return result
-end
+end
diff --git a/src/app/devtools.jl b/src/app/devtools.jl
@@ -3,8 +3,8 @@ struct DevTools
  props_check::Bool
  serve_dev_bundles::Bool
  hot_reload::Bool
- hot_reload_interval::Float32
- hot_reload_watch_interval::Float32
+ hot_reload_interval::Float64
+ hot_reload_watch_interval::Float64
  hot_reload_max_retry::Int
  silence_routes_logging::Bool
  prune_errors::Bool

diff --git a/src/handler/handlers.jl b/src/handler/handlers.jl
@@ -18,6 +18,7 @@ function process_dependencies(request::HTTP.Request, state::HandlerState)
 end
 
 function process_index(request::HTTP.Request, state::HandlerState)
+ get_cache(state).need_recache && rebuild_cache!(state)
  return HTTP.Response(
  200,
  ["Content-Type" => "text/html"],
@@ -147,7 +148,7 @@ end
 
 function process_assets(request::HTTP.Request, state::HandlerState; file_path::AbstractString)
  app = state.app
- filename = joinpath(get_setting(app, :assets_folder), file_path)
+ filename = joinpath(get_assets_path(app), file_path)
 
  try
  headers = Pair{String,String}[]
@@ -161,7 +162,47 @@ function process_assets(request::HTTP.Request, state::HandlerState; file_path::A
 
 end
 
-const dash_router = HTTP.Router()
+function process_reload_hash(request::HTTP.Request, state::HandlerState)
+ reload_tuple = (
+ reloadHash = state.reload.hash,
+ hard = state.reload.hard,
+ packages = keys(state.cache.resources.files),
+ files = state.reload.changed_assets
+ ) 
+ state.reload.hard = false
+ state.reload.changed_assets = []
+ return HTTP.Response(200, ["Content-Type" => "application/json"], body = JSON2.write(reload_tuple))
+
+end
+
+function start_reload_poll(state::HandlerState)
+ folders = Set{String}()
+ push!(folders, get_assets_path(state.app))
+ push!(folders, state.registry.dash_renderer.path)
+ for pkg in values(state.registry.components)
+ push!(folders, pkg.path)
+ end
+ state.reload.task = @async poll_folders(folders; interval = get_devsetting(state.app, :hot_reload_watch_interval)) do file, ts, deleted
+ state.reload.hard = true
+ state.reload.hash = generate_hash()
+ assets_path = get_assets_path(state.app)
+ if startswith(file, assets_path)
+ state.cache.need_recache = true
+ rel_path = lstrip(
+ replace(relpath(file, assets_path), '\\'=>'/'),
+ '/'
+ )
+ push!(state.reload.changed_assets, 
+ ChangedAsset(
+ asset_path(state.app, rel_path), 
+ trunc(Int, ts),
+ endswith(file, "css")
+ )
+ )
+ end
+
+ end
+end
 
 validate_layout(layout::Component) = validate(layout)
 
@@ -180,6 +221,7 @@ function make_handler(app::DashApp, registry::ResourcesRegistry; check_layout =
  router = Router()
  add_route!(process_layout, router, "$(prefix)_dash-layout")
  add_route!(process_dependencies, router, "$(prefix)_dash-dependencies")
+ add_route!(process_reload_hash, router, "$(prefix)_reload-hash")
  add_route!(process_resource, router, "$(prefix)_dash-component-suites/<namespace>/<path>")
  add_route!(process_assets, router, "$(prefix)$(assets_url_path)/<file_path>")
  add_route!(process_callback, router, "POST", "$(prefix)_dash-update-component")
@@ -189,7 +231,12 @@ function make_handler(app::DashApp, registry::ResourcesRegistry; check_layout =
  handler = state_handler(router, state)
  get_setting(app, :compress) && (handler = compress_handler(handler))
 
- HTTP.handle(handler, HTTP.Request("GET", prefix)) #For handler precompilation
+ compile_request = HTTP.Request("GET", prefix)
+ HTTP.setheader(compile_request, "Accept-Encoding" => "gzip")
+ HTTP.handle(handler, compile_request) #For handler precompilation
+
+ get_devsetting(app, :hot_reload) && start_reload_poll(state)
+
  return handler
 end
 

diff --git a/src/handler/index_page.jl b/src/handler/index_page.jl
@@ -99,7 +99,7 @@ function index_page(app::DashApp, resources::ApplicationResources)
 
  result = interpolate_string(app.index_string,
  metas = metas_html(app),
- title = app.name,
+ title = app.title,
  favicon = favicon_html(app),
  css = css_html(app, resources),
  app_entry = app_entry_html(),

diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -3,6 +3,7 @@ All notable changes to this project will be documented in this file. This projec
 
 ### [UNRELEASED]
 ### Added
+- Support for hot reloading on application or asset changes [#25](plotly/Dash.jl#25)
 - Asset serving of CSS, JavaScript, and other resources [#18](plotly/Dash.jl#18)
 - Support for passing functions as layouts [#18](plotly/Dash.jl#18)
 - Resource registry for component assets [#18](plotly/Dash.jl#18)

diff --git a/Project.toml b/Project.toml
@@ -13,7 +13,9 @@ LibGit2 = "76f85450-5226-5b5a-8eaa-529ad045b433"
 MD5 = "6ac74813-4b46-53a4-afec-0b5dc9d7885c"
 MacroTools = "1914dd2f-81c6-5fcd-8719-6d5c9610ff09"
 PlotlyBase = "a03496cd-edff-5a9b-9e67-9cda94a718b5"
+Sockets = "6462fe0b-24de-5631-8697-dd941f90decc"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
+UUIDs = "cf7118a7-6976-5b1a-9a39-7adc72f591a4"
 
 [compat]
 DataStructures = "0.17.5"

diff --git a/README.md b/README.md
@@ -21,7 +21,7 @@ import Pkg; Pkg.add(Pkg.PackageSpec(url = "https://github.com/plotly/Dash.jl.git
 
 ```jldoctest
 julia> using Dash
-julia> app = dash("Test app", external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"])
+julia> app = dash(external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"])
 
 julia> app.layout = html_div() do
  html_h1("Hello Dash"),
@@ -55,7 +55,7 @@ __Once you have run the code to create the Dashboard, go to `http://127.0.0.1:80
 ```jldoctest
 
 julia> using Dash
-julia> app = dash("Test app", external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"])
+julia> app = dash(external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"])
 
 julia> app.layout = html_div() do
  dcc_input(id = "my-id", value="initial value", type = "text"),
@@ -76,7 +76,7 @@ julia> run_server(app, "0.0.0.0", 8080)
 ### States and Multiple Outputs
 ```jldoctest
 julia> using Dash
-julia> app = dash("Test app", external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"])
+julia> app = dash(external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"])
 
 julia> app.layout = html_div() do
  dcc_input(id = "my-id", value="initial value", type = "text"),

diff --git a/docs/src/index.md b/docs/src/index.md
@@ -33,7 +33,7 @@ import Pkg; Pkg.add("Dashboards")
 ```jldoctest
 julia> import HTTP
 julia> using Dashboards
-julia> app = Dash("Test app", external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
+julia> app = Dash(external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
  html_div() do
  html_h1("Hello Dashboards"),
  html_div("Dashboards: Julia interface for Dash"),
@@ -68,7 +68,7 @@ __Once you have run the code to create the Dashboard, go to `http://127.0.0.1:80
 ```jldoctest
 julia> import HTTP
 julia> using Dashboards
-julia> app = Dash("Test app", external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
+julia> app = Dash(external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
  html_div() do
  dcc_input(id = "my-id", value="initial value", type = "text"),
  html_div(id = "my-div") 
@@ -89,7 +89,7 @@ julia> HTTP.serve(handler, HTTP.Sockets.localhost, 8080)
 ```jldoctest
 julia> import HTTP
 julia> using Dashboards
-julia> app = Dash("Test app", external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
+julia> app = Dash(external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
  html_div() do
  dcc_input(id = "my-id", value="initial value", type = "text"),
  html_div(id = "my-div"),

diff --git a/src/Dash.jl b/src/Dash.jl
@@ -1,5 +1,6 @@
 module Dash
 import HTTP, JSON2, CodecZlib, MD5
+using Sockets
 using MacroTools
 const ROOT_PATH = realpath(joinpath(@__DIR__, ".."))
 include("Components.jl")
@@ -19,7 +20,6 @@ include("utils.jl")
 include("app.jl")
 include("resources/registry.jl")
 include("resources/application.jl")
-include("config.jl")
 include("handlers.jl")
 
 @doc """
@@ -31,7 +31,7 @@ Julia backend for [Plotly Dash](https://github.com/plotly/dash)
 ```julia
 
 using Dash
-app = dash("Test", external_stylesheets=["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
+app = dash(external_stylesheets=["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
  html_div() do
  dcc_input(id="graphTitle", value="Let's Dance!", type = "text"),
  html_div(id="outputID"), 
@@ -76,7 +76,7 @@ Run Dash server
 
 #Examples
 ```jldoctest
-julia> app = dash("Test") do
+julia> app = dash() do
  html_div() do
  html_h1("Test Dashboard")
  end
@@ -111,10 +111,53 @@ function run_server(app::DashApp, host = HTTP.Sockets.localhost, port = 8050;
  dev_tools_silence_routes_logging = dev_tools_silence_routes_logging,
  dev_tools_prune_errors = dev_tools_prune_errors
  )
- handler = make_handler(app);
- @info string("Running on http://", host, ":", port)
- HTTP.serve(handler, host, port)
-end
+ main_func = () -> begin
+ ccall(:jl_exit_on_sigint, Cvoid, (Cint,), 0)
+ handler = make_handler(app);
+ try
+ task = @async HTTP.serve(handler, host, port)
+ @info string("Running on http://", host, ":", port)
+ wait(task)
+ catch e
+ if e isa InterruptException
+ @info "exited"
+ else
+ rethrow(e)
+ end
+
+ end
+ end
+ start_server = () -> begin
+ handler = make_handler(app);
+ server = Sockets.listen(get_inetaddr(host, port))
+ task = @async HTTP.serve(handler, host, port; server = server)
+ @info string("Running on http://", host, ":", port)
+ return (server, task)
+ end
 
+ if get_devsetting(app, :hot_reload) && !is_hot_restart_available()
+ @warn "Hot reloading is disabled for interactive sessions. Please run your app using julia from the command line to take advantage of this feature."
+ end
+
+ if get_devsetting(app, :hot_reload) && is_hot_restart_available()
+ hot_restart(start_server, check_interval = get_devsetting(app, :hot_reload_watch_interval))
+ else
+ (server, task) = start_server()
+ try
+ wait(task)
+ println(task)
+ catch e
+ close(server)
+ if e isa InterruptException 
+ println("finished")
+ return
+ else
+ rethrow(e)
+ end
+ end
+ end
+end
+get_inetaddr(host::String, port::Integer) = Sockets.InetAddr(parse(IPAddr, host), port)
+get_inetaddr(host::IPAddr, port::Integer) = Sockets.InetAddr(host, port)
 
 end # module
diff --git a/src/app/callbacks.jl b/src/app/callbacks.jl
@@ -19,7 +19,7 @@ Create a callback that updates the output by calling function `func`.
 # Examples
 
 ```julia
-app = dash("Test") do
+app = dash() do
  html_div() do
  dcc_input(id="graphTitle", value="Let's Dance!", type = "text"),
  dcc_input(id="graphTitle2", value="Let's Dance!", type = "text"),

diff --git a/src/app/dashapp.jl b/src/app/dashapp.jl
@@ -25,14 +25,16 @@ Dash.jl's internal representation of a Dash application.
 This `struct` is not intended to be called directly; developers should create their Dash application using the `dash` function instead.
 """
 mutable struct DashApp
- name ::String
+ root_path ::String
+ is_interactive ::Bool
  config ::DashConfig
  index_string ::Union{String, Nothing}
+ title ::String
  layout ::Union{Nothing, Component, Function}
  devtools ::DevTools
  callbacks ::Dict{Symbol, Callback}
 
- DashApp(name, config, index_string) = new(name, config, index_string, nothing, DevTools(dash_env(Bool, "debug", false)), Dict{Symbol, Callback}())
+ DashApp(root_path, is_interactive, config, index_string, title = "Dash") = new(root_path, is_interactive, config, index_string, title, nothing, DevTools(dash_env(Bool, "debug", false)), Dict{Symbol, Callback}())
 
 end
 
@@ -41,6 +43,7 @@ function Base.setproperty!(app::DashApp, property::Symbol, value)
  property == :name && return set_name!(app, value)
  property == :index_string && return set_index_string!(app, value)
  property == :layout && return set_layout!(app::DashApp, value)
+ property == :title && return set_title!(app::DashApp, value)
 
  property in fieldnames(DashApp) && error("The property `$(property)` of `DashApp` is read-only")
 
@@ -51,6 +54,10 @@ function set_name!(app::DashApp, name)
  setfield!(app, :name, name)
 end
 
+function set_title!(app::DashApp, title)
+ setfield!(app, :title, title)
+end
+
 get_name(app::DashApp) = app.name
 
 function set_layout!(app::DashApp, component::Union{Component,Function})
@@ -106,6 +113,8 @@ get_devsetting(app::DashApp, name::Symbol) = getproperty(app.devtools, name)
 
 get_setting(app::DashApp, name::Symbol) = getproperty(app.config, name)
 
+get_assets_path(app::DashApp) = joinpath(app.root_path, get_setting(app, :assets_folder))
+
 """
  dash(name::String;
  external_stylesheets,
@@ -134,7 +143,6 @@ If a parameter can be set by an environment variable, that is listed as:
  Values provided here take precedence over environment variables.
 
 # Arguments
-- `name::String` - The name of your application
 - `assets_folder::String` - a path, relative to the current working directory,
  for extra files to be used in the browser. Default `'assets'`. All .js and .css files will be loaded immediately unless excluded by `assets_ignore`, and other files such as images will be served if requested.
 
@@ -212,7 +220,7 @@ If a parameter can be set by an environment variable, that is listed as:
  files and data served by HTTP.jl when supported by the client. Set to
  ``false`` to disable compression completely.
 """
-function dash(name::String = dash_env("dash_name", "");
+function dash(;
  external_stylesheets = ExternalSrcType[],
  external_scripts = ExternalSrcType[],
  url_base_pathname = dash_env("url_base_pathname"), 
@@ -242,7 +250,7 @@ function dash(name::String = dash_env("dash_name", "");
  requests_pathname_prefix,
  routes_pathname_prefix
  )...,
-absolute_assets_path(assets_folder),
+ assets_folder,
  lstrip(assets_url_path, '/'),
  assets_ignore, 
  serve_locally, 
@@ -254,6 +262,6 @@ function dash(name::String = dash_env("dash_name", "");
  show_undo_redo,
  compress
  )
- result = DashApp(name, config, index_string)
+ result = DashApp(app_root_path(), isinteractive(), config, index_string)
  return result
-end
+end
diff --git a/src/app/devtools.jl b/src/app/devtools.jl
@@ -3,8 +3,8 @@ struct DevTools
  props_check::Bool
  serve_dev_bundles::Bool
  hot_reload::Bool
- hot_reload_interval::Float32
- hot_reload_watch_interval::Float32
+ hot_reload_interval::Float64
+ hot_reload_watch_interval::Float64
  hot_reload_max_retry::Int
  silence_routes_logging::Bool
  prune_errors::Bool

diff --git a/src/handler/handlers.jl b/src/handler/handlers.jl
@@ -18,6 +18,7 @@ function process_dependencies(request::HTTP.Request, state::HandlerState)
 end
 
 function process_index(request::HTTP.Request, state::HandlerState)
+ get_cache(state).need_recache && rebuild_cache!(state)
  return HTTP.Response(
  200,
  ["Content-Type" => "text/html"],
@@ -147,7 +148,7 @@ end
 
 function process_assets(request::HTTP.Request, state::HandlerState; file_path::AbstractString)
  app = state.app
- filename = joinpath(get_setting(app, :assets_folder), file_path)
+ filename = joinpath(get_assets_path(app), file_path)
 
  try
  headers = Pair{String,String}[]
@@ -161,7 +162,47 @@ function process_assets(request::HTTP.Request, state::HandlerState; file_path::A
 
 end
 
-const dash_router = HTTP.Router()
+function process_reload_hash(request::HTTP.Request, state::HandlerState)
+ reload_tuple = (
+ reloadHash = state.reload.hash,
+ hard = state.reload.hard,
+ packages = keys(state.cache.resources.files),
+ files = state.reload.changed_assets
+ ) 
+ state.reload.hard = false
+ state.reload.changed_assets = []
+ return HTTP.Response(200, ["Content-Type" => "application/json"], body = JSON2.write(reload_tuple))
+
+end
+
+function start_reload_poll(state::HandlerState)
+ folders = Set{String}()
+ push!(folders, get_assets_path(state.app))
+ push!(folders, state.registry.dash_renderer.path)
+ for pkg in values(state.registry.components)
+ push!(folders, pkg.path)
+ end
+ state.reload.task = @async poll_folders(folders; interval = get_devsetting(state.app, :hot_reload_watch_interval)) do file, ts, deleted
+ state.reload.hard = true
+ state.reload.hash = generate_hash()
+ assets_path = get_assets_path(state.app)
+ if startswith(file, assets_path)
+ state.cache.need_recache = true
+ rel_path = lstrip(
+ replace(relpath(file, assets_path), '\\'=>'/'),
+ '/'
+ )
+ push!(state.reload.changed_assets, 
+ ChangedAsset(
+ asset_path(state.app, rel_path), 
+ trunc(Int, ts),
+ endswith(file, "css")
+ )
+ )
+ end
+
+ end
+end
 
 validate_layout(layout::Component) = validate(layout)
 
@@ -180,6 +221,7 @@ function make_handler(app::DashApp, registry::ResourcesRegistry; check_layout =
  router = Router()
  add_route!(process_layout, router, "$(prefix)_dash-layout")
  add_route!(process_dependencies, router, "$(prefix)_dash-dependencies")
+ add_route!(process_reload_hash, router, "$(prefix)_reload-hash")
  add_route!(process_resource, router, "$(prefix)_dash-component-suites/<namespace>/<path>")
  add_route!(process_assets, router, "$(prefix)$(assets_url_path)/<file_path>")
  add_route!(process_callback, router, "POST", "$(prefix)_dash-update-component")
@@ -189,7 +231,12 @@ function make_handler(app::DashApp, registry::ResourcesRegistry; check_layout =
  handler = state_handler(router, state)
  get_setting(app, :compress) && (handler = compress_handler(handler))
 
- HTTP.handle(handler, HTTP.Request("GET", prefix)) #For handler precompilation
+ compile_request = HTTP.Request("GET", prefix)
+ HTTP.setheader(compile_request, "Accept-Encoding" => "gzip")
+ HTTP.handle(handler, compile_request) #For handler precompilation
+
+ get_devsetting(app, :hot_reload) && start_reload_poll(state)
+
  return handler
 end
 

diff --git a/src/handler/index_page.jl b/src/handler/index_page.jl
@@ -99,7 +99,7 @@ function index_page(app::DashApp, resources::ApplicationResources)
 
  result = interpolate_string(app.index_string,
  metas = metas_html(app),
- title = app.name,
+ title = app.title,
  favicon = favicon_html(app),
  css = css_html(app, resources),
  app_entry = app_entry_html(),

diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -3,6 +3,7 @@ All notable changes to this project will be documented in this file. This projec
 
 ### [UNRELEASED]
 ### Added
+- Support for hot reloading on application or asset changes [#25](plotly/Dash.jl#25)
 - Asset serving of CSS, JavaScript, and other resources [#18](plotly/Dash.jl#18)
 - Support for passing functions as layouts [#18](plotly/Dash.jl#18)
 - Resource registry for component assets [#18](plotly/Dash.jl#18)

diff --git a/Project.toml b/Project.toml
@@ -13,7 +13,9 @@ LibGit2 = "76f85450-5226-5b5a-8eaa-529ad045b433"
 MD5 = "6ac74813-4b46-53a4-afec-0b5dc9d7885c"
 MacroTools = "1914dd2f-81c6-5fcd-8719-6d5c9610ff09"
 PlotlyBase = "a03496cd-edff-5a9b-9e67-9cda94a718b5"
+Sockets = "6462fe0b-24de-5631-8697-dd941f90decc"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
+UUIDs = "cf7118a7-6976-5b1a-9a39-7adc72f591a4"
 
 [compat]
 DataStructures = "0.17.5"

diff --git a/README.md b/README.md
@@ -21,7 +21,7 @@ import Pkg; Pkg.add(Pkg.PackageSpec(url = "https://github.com/plotly/Dash.jl.git
 
 ```jldoctest
 julia> using Dash
-julia> app = dash("Test app", external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"])
+julia> app = dash(external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"])
 
 julia> app.layout = html_div() do
  html_h1("Hello Dash"),
@@ -55,7 +55,7 @@ __Once you have run the code to create the Dashboard, go to `http://127.0.0.1:80
 ```jldoctest
 
 julia> using Dash
-julia> app = dash("Test app", external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"])
+julia> app = dash(external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"])
 
 julia> app.layout = html_div() do
  dcc_input(id = "my-id", value="initial value", type = "text"),
@@ -76,7 +76,7 @@ julia> run_server(app, "0.0.0.0", 8080)
 ### States and Multiple Outputs
 ```jldoctest
 julia> using Dash
-julia> app = dash("Test app", external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"])
+julia> app = dash(external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"])
 
 julia> app.layout = html_div() do
  dcc_input(id = "my-id", value="initial value", type = "text"),

diff --git a/docs/src/index.md b/docs/src/index.md
@@ -33,7 +33,7 @@ import Pkg; Pkg.add("Dashboards")
 ```jldoctest
 julia> import HTTP
 julia> using Dashboards
-julia> app = Dash("Test app", external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
+julia> app = Dash(external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
  html_div() do
  html_h1("Hello Dashboards"),
  html_div("Dashboards: Julia interface for Dash"),
@@ -68,7 +68,7 @@ __Once you have run the code to create the Dashboard, go to `http://127.0.0.1:80
 ```jldoctest
 julia> import HTTP
 julia> using Dashboards
-julia> app = Dash("Test app", external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
+julia> app = Dash(external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
  html_div() do
  dcc_input(id = "my-id", value="initial value", type = "text"),
  html_div(id = "my-div") 
@@ -89,7 +89,7 @@ julia> HTTP.serve(handler, HTTP.Sockets.localhost, 8080)
 ```jldoctest
 julia> import HTTP
 julia> using Dashboards
-julia> app = Dash("Test app", external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
+julia> app = Dash(external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
  html_div() do
  dcc_input(id = "my-id", value="initial value", type = "text"),
  html_div(id = "my-div"),

diff --git a/src/Dash.jl b/src/Dash.jl
@@ -1,5 +1,6 @@
 module Dash
 import HTTP, JSON2, CodecZlib, MD5
+using Sockets
 using MacroTools
 const ROOT_PATH = realpath(joinpath(@__DIR__, ".."))
 include("Components.jl")
@@ -19,7 +20,6 @@ include("utils.jl")
 include("app.jl")
 include("resources/registry.jl")
 include("resources/application.jl")
-include("config.jl")
 include("handlers.jl")
 
 @doc """
@@ -31,7 +31,7 @@ Julia backend for [Plotly Dash](https://github.com/plotly/dash)
 ```julia
 
 using Dash
-app = dash("Test", external_stylesheets=["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
+app = dash(external_stylesheets=["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
  html_div() do
  dcc_input(id="graphTitle", value="Let's Dance!", type = "text"),
  html_div(id="outputID"), 
@@ -76,7 +76,7 @@ Run Dash server
 
 #Examples
 ```jldoctest
-julia> app = dash("Test") do
+julia> app = dash() do
  html_div() do
  html_h1("Test Dashboard")
  end
@@ -111,10 +111,53 @@ function run_server(app::DashApp, host = HTTP.Sockets.localhost, port = 8050;
  dev_tools_silence_routes_logging = dev_tools_silence_routes_logging,
  dev_tools_prune_errors = dev_tools_prune_errors
  )
- handler = make_handler(app);
- @info string("Running on http://", host, ":", port)
- HTTP.serve(handler, host, port)
-end
+ main_func = () -> begin
+ ccall(:jl_exit_on_sigint, Cvoid, (Cint,), 0)
+ handler = make_handler(app);
+ try
+ task = @async HTTP.serve(handler, host, port)
+ @info string("Running on http://", host, ":", port)
+ wait(task)
+ catch e
+ if e isa InterruptException
+ @info "exited"
+ else
+ rethrow(e)
+ end
+
+ end
+ end
+ start_server = () -> begin
+ handler = make_handler(app);
+ server = Sockets.listen(get_inetaddr(host, port))
+ task = @async HTTP.serve(handler, host, port; server = server)
+ @info string("Running on http://", host, ":", port)
+ return (server, task)
+ end
 
+ if get_devsetting(app, :hot_reload) && !is_hot_restart_available()
+ @warn "Hot reloading is disabled for interactive sessions. Please run your app using julia from the command line to take advantage of this feature."
+ end
+
+ if get_devsetting(app, :hot_reload) && is_hot_restart_available()
+ hot_restart(start_server, check_interval = get_devsetting(app, :hot_reload_watch_interval))
+ else
+ (server, task) = start_server()
+ try
+ wait(task)
+ println(task)
+ catch e
+ close(server)
+ if e isa InterruptException 
+ println("finished")
+ return
+ else
+ rethrow(e)
+ end
+ end
+ end
+end
+get_inetaddr(host::String, port::Integer) = Sockets.InetAddr(parse(IPAddr, host), port)
+get_inetaddr(host::IPAddr, port::Integer) = Sockets.InetAddr(host, port)
 
 end # module
diff --git a/src/app/callbacks.jl b/src/app/callbacks.jl
@@ -19,7 +19,7 @@ Create a callback that updates the output by calling function `func`.
 # Examples
 
 ```julia
-app = dash("Test") do
+app = dash() do
  html_div() do
  dcc_input(id="graphTitle", value="Let's Dance!", type = "text"),
  dcc_input(id="graphTitle2", value="Let's Dance!", type = "text"),

diff --git a/src/app/dashapp.jl b/src/app/dashapp.jl
@@ -25,14 +25,16 @@ Dash.jl's internal representation of a Dash application.
 This `struct` is not intended to be called directly; developers should create their Dash application using the `dash` function instead.
 """
 mutable struct DashApp
- name ::String
+ root_path ::String
+ is_interactive ::Bool
  config ::DashConfig
  index_string ::Union{String, Nothing}
+ title ::String
  layout ::Union{Nothing, Component, Function}
  devtools ::DevTools
  callbacks ::Dict{Symbol, Callback}
 
- DashApp(name, config, index_string) = new(name, config, index_string, nothing, DevTools(dash_env(Bool, "debug", false)), Dict{Symbol, Callback}())
+ DashApp(root_path, is_interactive, config, index_string, title = "Dash") = new(root_path, is_interactive, config, index_string, title, nothing, DevTools(dash_env(Bool, "debug", false)), Dict{Symbol, Callback}())
 
 end
 
@@ -41,6 +43,7 @@ function Base.setproperty!(app::DashApp, property::Symbol, value)
  property == :name && return set_name!(app, value)
  property == :index_string && return set_index_string!(app, value)
  property == :layout && return set_layout!(app::DashApp, value)
+ property == :title && return set_title!(app::DashApp, value)
 
  property in fieldnames(DashApp) && error("The property `$(property)` of `DashApp` is read-only")
 
@@ -51,6 +54,10 @@ function set_name!(app::DashApp, name)
  setfield!(app, :name, name)
 end
 
+function set_title!(app::DashApp, title)
+ setfield!(app, :title, title)
+end
+
 get_name(app::DashApp) = app.name
 
 function set_layout!(app::DashApp, component::Union{Component,Function})
@@ -106,6 +113,8 @@ get_devsetting(app::DashApp, name::Symbol) = getproperty(app.devtools, name)
 
 get_setting(app::DashApp, name::Symbol) = getproperty(app.config, name)
 
+get_assets_path(app::DashApp) = joinpath(app.root_path, get_setting(app, :assets_folder))
+
 """
  dash(name::String;
  external_stylesheets,
@@ -134,7 +143,6 @@ If a parameter can be set by an environment variable, that is listed as:
  Values provided here take precedence over environment variables.
 
 # Arguments
-- `name::String` - The name of your application
 - `assets_folder::String` - a path, relative to the current working directory,
  for extra files to be used in the browser. Default `'assets'`. All .js and .css files will be loaded immediately unless excluded by `assets_ignore`, and other files such as images will be served if requested.
 
@@ -212,7 +220,7 @@ If a parameter can be set by an environment variable, that is listed as:
  files and data served by HTTP.jl when supported by the client. Set to
  ``false`` to disable compression completely.
 """
-function dash(name::String = dash_env("dash_name", "");
+function dash(;
  external_stylesheets = ExternalSrcType[],
  external_scripts = ExternalSrcType[],
  url_base_pathname = dash_env("url_base_pathname"), 
@@ -242,7 +250,7 @@ function dash(name::String = dash_env("dash_name", "");
  requests_pathname_prefix,
  routes_pathname_prefix
  )...,
-absolute_assets_path(assets_folder),
+ assets_folder,
  lstrip(assets_url_path, '/'),
  assets_ignore, 
  serve_locally, 
@@ -254,6 +262,6 @@ function dash(name::String = dash_env("dash_name", "");
  show_undo_redo,
  compress
  )
- result = DashApp(name, config, index_string)
+ result = DashApp(app_root_path(), isinteractive(), config, index_string)
  return result
-end
+end
diff --git a/src/app/devtools.jl b/src/app/devtools.jl
@@ -3,8 +3,8 @@ struct DevTools
  props_check::Bool
  serve_dev_bundles::Bool
  hot_reload::Bool
- hot_reload_interval::Float32
- hot_reload_watch_interval::Float32
+ hot_reload_interval::Float64
+ hot_reload_watch_interval::Float64
  hot_reload_max_retry::Int
  silence_routes_logging::Bool
  prune_errors::Bool

diff --git a/src/handler/handlers.jl b/src/handler/handlers.jl
@@ -18,6 +18,7 @@ function process_dependencies(request::HTTP.Request, state::HandlerState)
 end
 
 function process_index(request::HTTP.Request, state::HandlerState)
+ get_cache(state).need_recache && rebuild_cache!(state)
  return HTTP.Response(
  200,
  ["Content-Type" => "text/html"],
@@ -147,7 +148,7 @@ end
 
 function process_assets(request::HTTP.Request, state::HandlerState; file_path::AbstractString)
  app = state.app
- filename = joinpath(get_setting(app, :assets_folder), file_path)
+ filename = joinpath(get_assets_path(app), file_path)
 
  try
  headers = Pair{String,String}[]
@@ -161,7 +162,47 @@ function process_assets(request::HTTP.Request, state::HandlerState; file_path::A
 
 end
 
-const dash_router = HTTP.Router()
+function process_reload_hash(request::HTTP.Request, state::HandlerState)
+ reload_tuple = (
+ reloadHash = state.reload.hash,
+ hard = state.reload.hard,
+ packages = keys(state.cache.resources.files),
+ files = state.reload.changed_assets
+ ) 
+ state.reload.hard = false
+ state.reload.changed_assets = []
+ return HTTP.Response(200, ["Content-Type" => "application/json"], body = JSON2.write(reload_tuple))
+
+end
+
+function start_reload_poll(state::HandlerState)
+ folders = Set{String}()
+ push!(folders, get_assets_path(state.app))
+ push!(folders, state.registry.dash_renderer.path)
+ for pkg in values(state.registry.components)
+ push!(folders, pkg.path)
+ end
+ state.reload.task = @async poll_folders(folders; interval = get_devsetting(state.app, :hot_reload_watch_interval)) do file, ts, deleted
+ state.reload.hard = true
+ state.reload.hash = generate_hash()
+ assets_path = get_assets_path(state.app)
+ if startswith(file, assets_path)
+ state.cache.need_recache = true
+ rel_path = lstrip(
+ replace(relpath(file, assets_path), '\\'=>'/'),
+ '/'
+ )
+ push!(state.reload.changed_assets, 
+ ChangedAsset(
+ asset_path(state.app, rel_path), 
+ trunc(Int, ts),
+ endswith(file, "css")
+ )
+ )
+ end
+
+ end
+end
 
 validate_layout(layout::Component) = validate(layout)
 
@@ -180,6 +221,7 @@ function make_handler(app::DashApp, registry::ResourcesRegistry; check_layout =
  router = Router()
  add_route!(process_layout, router, "$(prefix)_dash-layout")
  add_route!(process_dependencies, router, "$(prefix)_dash-dependencies")
+ add_route!(process_reload_hash, router, "$(prefix)_reload-hash")
  add_route!(process_resource, router, "$(prefix)_dash-component-suites/<namespace>/<path>")
  add_route!(process_assets, router, "$(prefix)$(assets_url_path)/<file_path>")
  add_route!(process_callback, router, "POST", "$(prefix)_dash-update-component")
@@ -189,7 +231,12 @@ function make_handler(app::DashApp, registry::ResourcesRegistry; check_layout =
  handler = state_handler(router, state)
  get_setting(app, :compress) && (handler = compress_handler(handler))
 
- HTTP.handle(handler, HTTP.Request("GET", prefix)) #For handler precompilation
+ compile_request = HTTP.Request("GET", prefix)
+ HTTP.setheader(compile_request, "Accept-Encoding" => "gzip")
+ HTTP.handle(handler, compile_request) #For handler precompilation
+
+ get_devsetting(app, :hot_reload) && start_reload_poll(state)
+
  return handler
 end
 

diff --git a/src/handler/index_page.jl b/src/handler/index_page.jl
@@ -99,7 +99,7 @@ function index_page(app::DashApp, resources::ApplicationResources)
 
  result = interpolate_string(app.index_string,
  metas = metas_html(app),
- title = app.name,
+ title = app.title,
  favicon = favicon_html(app),
  css = css_html(app, resources),
  app_entry = app_entry_html(),

diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -3,6 +3,7 @@ All notable changes to this project will be documented in this file. This projec
 
 ### [UNRELEASED]
 ### Added
+- Support for hot reloading on application or asset changes [#25](plotly/Dash.jl#25)
 - Asset serving of CSS, JavaScript, and other resources [#18](plotly/Dash.jl#18)
 - Support for passing functions as layouts [#18](plotly/Dash.jl#18)
 - Resource registry for component assets [#18](plotly/Dash.jl#18)

diff --git a/Project.toml b/Project.toml
@@ -13,7 +13,9 @@ LibGit2 = "76f85450-5226-5b5a-8eaa-529ad045b433"
 MD5 = "6ac74813-4b46-53a4-afec-0b5dc9d7885c"
 MacroTools = "1914dd2f-81c6-5fcd-8719-6d5c9610ff09"
 PlotlyBase = "a03496cd-edff-5a9b-9e67-9cda94a718b5"
+Sockets = "6462fe0b-24de-5631-8697-dd941f90decc"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
+UUIDs = "cf7118a7-6976-5b1a-9a39-7adc72f591a4"
 
 [compat]
 DataStructures = "0.17.5"

diff --git a/README.md b/README.md
@@ -21,7 +21,7 @@ import Pkg; Pkg.add(Pkg.PackageSpec(url = "https://github.com/plotly/Dash.jl.git
 
 ```jldoctest
 julia> using Dash
-julia> app = dash("Test app", external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"])
+julia> app = dash(external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"])
 
 julia> app.layout = html_div() do
  html_h1("Hello Dash"),
@@ -55,7 +55,7 @@ __Once you have run the code to create the Dashboard, go to `http://127.0.0.1:80
 ```jldoctest
 
 julia> using Dash
-julia> app = dash("Test app", external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"])
+julia> app = dash(external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"])
 
 julia> app.layout = html_div() do
  dcc_input(id = "my-id", value="initial value", type = "text"),
@@ -76,7 +76,7 @@ julia> run_server(app, "0.0.0.0", 8080)
 ### States and Multiple Outputs
 ```jldoctest
 julia> using Dash
-julia> app = dash("Test app", external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"])
+julia> app = dash(external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"])
 
 julia> app.layout = html_div() do
  dcc_input(id = "my-id", value="initial value", type = "text"),

diff --git a/docs/src/index.md b/docs/src/index.md
@@ -33,7 +33,7 @@ import Pkg; Pkg.add("Dashboards")
 ```jldoctest
 julia> import HTTP
 julia> using Dashboards
-julia> app = Dash("Test app", external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
+julia> app = Dash(external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
  html_div() do
  html_h1("Hello Dashboards"),
  html_div("Dashboards: Julia interface for Dash"),
@@ -68,7 +68,7 @@ __Once you have run the code to create the Dashboard, go to `http://127.0.0.1:80
 ```jldoctest
 julia> import HTTP
 julia> using Dashboards
-julia> app = Dash("Test app", external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
+julia> app = Dash(external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
  html_div() do
  dcc_input(id = "my-id", value="initial value", type = "text"),
  html_div(id = "my-div") 
@@ -89,7 +89,7 @@ julia> HTTP.serve(handler, HTTP.Sockets.localhost, 8080)
 ```jldoctest
 julia> import HTTP
 julia> using Dashboards
-julia> app = Dash("Test app", external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
+julia> app = Dash(external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
  html_div() do
  dcc_input(id = "my-id", value="initial value", type = "text"),
  html_div(id = "my-div"),

diff --git a/src/Dash.jl b/src/Dash.jl
@@ -1,5 +1,6 @@
 module Dash
 import HTTP, JSON2, CodecZlib, MD5
+using Sockets
 using MacroTools
 const ROOT_PATH = realpath(joinpath(@__DIR__, ".."))
 include("Components.jl")
@@ -19,7 +20,6 @@ include("utils.jl")
 include("app.jl")
 include("resources/registry.jl")
 include("resources/application.jl")
-include("config.jl")
 include("handlers.jl")
 
 @doc """
@@ -31,7 +31,7 @@ Julia backend for [Plotly Dash](https://github.com/plotly/dash)
 ```julia
 
 using Dash
-app = dash("Test", external_stylesheets=["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
+app = dash(external_stylesheets=["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
  html_div() do
  dcc_input(id="graphTitle", value="Let's Dance!", type = "text"),
  html_div(id="outputID"), 
@@ -76,7 +76,7 @@ Run Dash server
 
 #Examples
 ```jldoctest
-julia> app = dash("Test") do
+julia> app = dash() do
  html_div() do
  html_h1("Test Dashboard")
  end
@@ -111,10 +111,53 @@ function run_server(app::DashApp, host = HTTP.Sockets.localhost, port = 8050;
  dev_tools_silence_routes_logging = dev_tools_silence_routes_logging,
  dev_tools_prune_errors = dev_tools_prune_errors
  )
- handler = make_handler(app);
- @info string("Running on http://", host, ":", port)
- HTTP.serve(handler, host, port)
-end
+ main_func = () -> begin
+ ccall(:jl_exit_on_sigint, Cvoid, (Cint,), 0)
+ handler = make_handler(app);
+ try
+ task = @async HTTP.serve(handler, host, port)
+ @info string("Running on http://", host, ":", port)
+ wait(task)
+ catch e
+ if e isa InterruptException
+ @info "exited"
+ else
+ rethrow(e)
+ end
+
+ end
+ end
+ start_server = () -> begin
+ handler = make_handler(app);
+ server = Sockets.listen(get_inetaddr(host, port))
+ task = @async HTTP.serve(handler, host, port; server = server)
+ @info string("Running on http://", host, ":", port)
+ return (server, task)
+ end
 
+ if get_devsetting(app, :hot_reload) && !is_hot_restart_available()
+ @warn "Hot reloading is disabled for interactive sessions. Please run your app using julia from the command line to take advantage of this feature."
+ end
+
+ if get_devsetting(app, :hot_reload) && is_hot_restart_available()
+ hot_restart(start_server, check_interval = get_devsetting(app, :hot_reload_watch_interval))
+ else
+ (server, task) = start_server()
+ try
+ wait(task)
+ println(task)
+ catch e
+ close(server)
+ if e isa InterruptException 
+ println("finished")
+ return
+ else
+ rethrow(e)
+ end
+ end
+ end
+end
+get_inetaddr(host::String, port::Integer) = Sockets.InetAddr(parse(IPAddr, host), port)
+get_inetaddr(host::IPAddr, port::Integer) = Sockets.InetAddr(host, port)
 
 end # module
diff --git a/src/app/callbacks.jl b/src/app/callbacks.jl
@@ -19,7 +19,7 @@ Create a callback that updates the output by calling function `func`.
 # Examples
 
 ```julia
-app = dash("Test") do
+app = dash() do
  html_div() do
  dcc_input(id="graphTitle", value="Let's Dance!", type = "text"),
  dcc_input(id="graphTitle2", value="Let's Dance!", type = "text"),

diff --git a/src/app/dashapp.jl b/src/app/dashapp.jl
@@ -25,14 +25,16 @@ Dash.jl's internal representation of a Dash application.
 This `struct` is not intended to be called directly; developers should create their Dash application using the `dash` function instead.
 """
 mutable struct DashApp
- name ::String
+ root_path ::String
+ is_interactive ::Bool
  config ::DashConfig
  index_string ::Union{String, Nothing}
+ title ::String
  layout ::Union{Nothing, Component, Function}
  devtools ::DevTools
  callbacks ::Dict{Symbol, Callback}
 
- DashApp(name, config, index_string) = new(name, config, index_string, nothing, DevTools(dash_env(Bool, "debug", false)), Dict{Symbol, Callback}())
+ DashApp(root_path, is_interactive, config, index_string, title = "Dash") = new(root_path, is_interactive, config, index_string, title, nothing, DevTools(dash_env(Bool, "debug", false)), Dict{Symbol, Callback}())
 
 end
 
@@ -41,6 +43,7 @@ function Base.setproperty!(app::DashApp, property::Symbol, value)
  property == :name && return set_name!(app, value)
  property == :index_string && return set_index_string!(app, value)
  property == :layout && return set_layout!(app::DashApp, value)
+ property == :title && return set_title!(app::DashApp, value)
 
  property in fieldnames(DashApp) && error("The property `$(property)` of `DashApp` is read-only")
 
@@ -51,6 +54,10 @@ function set_name!(app::DashApp, name)
  setfield!(app, :name, name)
 end
 
+function set_title!(app::DashApp, title)
+ setfield!(app, :title, title)
+end
+
 get_name(app::DashApp) = app.name
 
 function set_layout!(app::DashApp, component::Union{Component,Function})
@@ -106,6 +113,8 @@ get_devsetting(app::DashApp, name::Symbol) = getproperty(app.devtools, name)
 
 get_setting(app::DashApp, name::Symbol) = getproperty(app.config, name)
 
+get_assets_path(app::DashApp) = joinpath(app.root_path, get_setting(app, :assets_folder))
+
 """
  dash(name::String;
  external_stylesheets,
@@ -134,7 +143,6 @@ If a parameter can be set by an environment variable, that is listed as:
  Values provided here take precedence over environment variables.
 
 # Arguments
-- `name::String` - The name of your application
 - `assets_folder::String` - a path, relative to the current working directory,
  for extra files to be used in the browser. Default `'assets'`. All .js and .css files will be loaded immediately unless excluded by `assets_ignore`, and other files such as images will be served if requested.
 
@@ -212,7 +220,7 @@ If a parameter can be set by an environment variable, that is listed as:
  files and data served by HTTP.jl when supported by the client. Set to
  ``false`` to disable compression completely.
 """
-function dash(name::String = dash_env("dash_name", "");
+function dash(;
  external_stylesheets = ExternalSrcType[],
  external_scripts = ExternalSrcType[],
  url_base_pathname = dash_env("url_base_pathname"), 
@@ -242,7 +250,7 @@ function dash(name::String = dash_env("dash_name", "");
  requests_pathname_prefix,
  routes_pathname_prefix
  )...,
-absolute_assets_path(assets_folder),
+ assets_folder,
  lstrip(assets_url_path, '/'),
  assets_ignore, 
  serve_locally, 
@@ -254,6 +262,6 @@ function dash(name::String = dash_env("dash_name", "");
  show_undo_redo,
  compress
  )
- result = DashApp(name, config, index_string)
+ result = DashApp(app_root_path(), isinteractive(), config, index_string)
  return result
-end
+end
diff --git a/src/app/devtools.jl b/src/app/devtools.jl
@@ -3,8 +3,8 @@ struct DevTools
  props_check::Bool
  serve_dev_bundles::Bool
  hot_reload::Bool
- hot_reload_interval::Float32
- hot_reload_watch_interval::Float32
+ hot_reload_interval::Float64
+ hot_reload_watch_interval::Float64
  hot_reload_max_retry::Int
  silence_routes_logging::Bool
  prune_errors::Bool

diff --git a/src/handler/handlers.jl b/src/handler/handlers.jl
@@ -18,6 +18,7 @@ function process_dependencies(request::HTTP.Request, state::HandlerState)
 end
 
 function process_index(request::HTTP.Request, state::HandlerState)
+ get_cache(state).need_recache && rebuild_cache!(state)
  return HTTP.Response(
  200,
  ["Content-Type" => "text/html"],
@@ -147,7 +148,7 @@ end
 
 function process_assets(request::HTTP.Request, state::HandlerState; file_path::AbstractString)
  app = state.app
- filename = joinpath(get_setting(app, :assets_folder), file_path)
+ filename = joinpath(get_assets_path(app), file_path)
 
  try
  headers = Pair{String,String}[]
@@ -161,7 +162,47 @@ function process_assets(request::HTTP.Request, state::HandlerState; file_path::A
 
 end
 
-const dash_router = HTTP.Router()
+function process_reload_hash(request::HTTP.Request, state::HandlerState)
+ reload_tuple = (
+ reloadHash = state.reload.hash,
+ hard = state.reload.hard,
+ packages = keys(state.cache.resources.files),
+ files = state.reload.changed_assets
+ ) 
+ state.reload.hard = false
+ state.reload.changed_assets = []
+ return HTTP.Response(200, ["Content-Type" => "application/json"], body = JSON2.write(reload_tuple))
+
+end
+
+function start_reload_poll(state::HandlerState)
+ folders = Set{String}()
+ push!(folders, get_assets_path(state.app))
+ push!(folders, state.registry.dash_renderer.path)
+ for pkg in values(state.registry.components)
+ push!(folders, pkg.path)
+ end
+ state.reload.task = @async poll_folders(folders; interval = get_devsetting(state.app, :hot_reload_watch_interval)) do file, ts, deleted
+ state.reload.hard = true
+ state.reload.hash = generate_hash()
+ assets_path = get_assets_path(state.app)
+ if startswith(file, assets_path)
+ state.cache.need_recache = true
+ rel_path = lstrip(
+ replace(relpath(file, assets_path), '\\'=>'/'),
+ '/'
+ )
+ push!(state.reload.changed_assets, 
+ ChangedAsset(
+ asset_path(state.app, rel_path), 
+ trunc(Int, ts),
+ endswith(file, "css")
+ )
+ )
+ end
+
+ end
+end
 
 validate_layout(layout::Component) = validate(layout)
 
@@ -180,6 +221,7 @@ function make_handler(app::DashApp, registry::ResourcesRegistry; check_layout =
  router = Router()
  add_route!(process_layout, router, "$(prefix)_dash-layout")
  add_route!(process_dependencies, router, "$(prefix)_dash-dependencies")
+ add_route!(process_reload_hash, router, "$(prefix)_reload-hash")
  add_route!(process_resource, router, "$(prefix)_dash-component-suites/<namespace>/<path>")
  add_route!(process_assets, router, "$(prefix)$(assets_url_path)/<file_path>")
  add_route!(process_callback, router, "POST", "$(prefix)_dash-update-component")
@@ -189,7 +231,12 @@ function make_handler(app::DashApp, registry::ResourcesRegistry; check_layout =
  handler = state_handler(router, state)
  get_setting(app, :compress) && (handler = compress_handler(handler))
 
- HTTP.handle(handler, HTTP.Request("GET", prefix)) #For handler precompilation
+ compile_request = HTTP.Request("GET", prefix)
+ HTTP.setheader(compile_request, "Accept-Encoding" => "gzip")
+ HTTP.handle(handler, compile_request) #For handler precompilation
+
+ get_devsetting(app, :hot_reload) && start_reload_poll(state)
+
  return handler
 end
 

diff --git a/src/handler/index_page.jl b/src/handler/index_page.jl
@@ -99,7 +99,7 @@ function index_page(app::DashApp, resources::ApplicationResources)
 
  result = interpolate_string(app.index_string,
  metas = metas_html(app),
- title = app.name,
+ title = app.title,
  favicon = favicon_html(app),
  css = css_html(app, resources),
  app_entry = app_entry_html(),

diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -3,6 +3,7 @@ All notable changes to this project will be documented in this file. This projec
 
 ### [UNRELEASED]
 ### Added
+- Support for hot reloading on application or asset changes [#25](plotly/Dash.jl#25)
 - Asset serving of CSS, JavaScript, and other resources [#18](plotly/Dash.jl#18)
 - Support for passing functions as layouts [#18](plotly/Dash.jl#18)
 - Resource registry for component assets [#18](plotly/Dash.jl#18)

diff --git a/Project.toml b/Project.toml
@@ -13,7 +13,9 @@ LibGit2 = "76f85450-5226-5b5a-8eaa-529ad045b433"
 MD5 = "6ac74813-4b46-53a4-afec-0b5dc9d7885c"
 MacroTools = "1914dd2f-81c6-5fcd-8719-6d5c9610ff09"
 PlotlyBase = "a03496cd-edff-5a9b-9e67-9cda94a718b5"
+Sockets = "6462fe0b-24de-5631-8697-dd941f90decc"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
+UUIDs = "cf7118a7-6976-5b1a-9a39-7adc72f591a4"
 
 [compat]
 DataStructures = "0.17.5"

diff --git a/README.md b/README.md
@@ -21,7 +21,7 @@ import Pkg; Pkg.add(Pkg.PackageSpec(url = "https://github.com/plotly/Dash.jl.git
 
 ```jldoctest
 julia> using Dash
-julia> app = dash("Test app", external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"])
+julia> app = dash(external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"])
 
 julia> app.layout = html_div() do
  html_h1("Hello Dash"),
@@ -55,7 +55,7 @@ __Once you have run the code to create the Dashboard, go to `http://127.0.0.1:80
 ```jldoctest
 
 julia> using Dash
-julia> app = dash("Test app", external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"])
+julia> app = dash(external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"])
 
 julia> app.layout = html_div() do
  dcc_input(id = "my-id", value="initial value", type = "text"),
@@ -76,7 +76,7 @@ julia> run_server(app, "0.0.0.0", 8080)
 ### States and Multiple Outputs
 ```jldoctest
 julia> using Dash
-julia> app = dash("Test app", external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"])
+julia> app = dash(external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"])
 
 julia> app.layout = html_div() do
  dcc_input(id = "my-id", value="initial value", type = "text"),

diff --git a/docs/src/index.md b/docs/src/index.md
@@ -33,7 +33,7 @@ import Pkg; Pkg.add("Dashboards")
 ```jldoctest
 julia> import HTTP
 julia> using Dashboards
-julia> app = Dash("Test app", external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
+julia> app = Dash(external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
  html_div() do
  html_h1("Hello Dashboards"),
  html_div("Dashboards: Julia interface for Dash"),
@@ -68,7 +68,7 @@ __Once you have run the code to create the Dashboard, go to `http://127.0.0.1:80
 ```jldoctest
 julia> import HTTP
 julia> using Dashboards
-julia> app = Dash("Test app", external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
+julia> app = Dash(external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
  html_div() do
  dcc_input(id = "my-id", value="initial value", type = "text"),
  html_div(id = "my-div") 
@@ -89,7 +89,7 @@ julia> HTTP.serve(handler, HTTP.Sockets.localhost, 8080)
 ```jldoctest
 julia> import HTTP
 julia> using Dashboards
-julia> app = Dash("Test app", external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
+julia> app = Dash(external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
  html_div() do
  dcc_input(id = "my-id", value="initial value", type = "text"),
  html_div(id = "my-div"),

diff --git a/src/Dash.jl b/src/Dash.jl
@@ -1,5 +1,6 @@
 module Dash
 import HTTP, JSON2, CodecZlib, MD5
+using Sockets
 using MacroTools
 const ROOT_PATH = realpath(joinpath(@__DIR__, ".."))
 include("Components.jl")
@@ -19,7 +20,6 @@ include("utils.jl")
 include("app.jl")
 include("resources/registry.jl")
 include("resources/application.jl")
-include("config.jl")
 include("handlers.jl")
 
 @doc """
@@ -31,7 +31,7 @@ Julia backend for [Plotly Dash](https://github.com/plotly/dash)
 ```julia
 
 using Dash
-app = dash("Test", external_stylesheets=["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
+app = dash(external_stylesheets=["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
  html_div() do
  dcc_input(id="graphTitle", value="Let's Dance!", type = "text"),
  html_div(id="outputID"), 
@@ -76,7 +76,7 @@ Run Dash server
 
 #Examples
 ```jldoctest
-julia> app = dash("Test") do
+julia> app = dash() do
  html_div() do
  html_h1("Test Dashboard")
  end
@@ -111,10 +111,53 @@ function run_server(app::DashApp, host = HTTP.Sockets.localhost, port = 8050;
  dev_tools_silence_routes_logging = dev_tools_silence_routes_logging,
  dev_tools_prune_errors = dev_tools_prune_errors
  )
- handler = make_handler(app);
- @info string("Running on http://", host, ":", port)
- HTTP.serve(handler, host, port)
-end
+ main_func = () -> begin
+ ccall(:jl_exit_on_sigint, Cvoid, (Cint,), 0)
+ handler = make_handler(app);
+ try
+ task = @async HTTP.serve(handler, host, port)
+ @info string("Running on http://", host, ":", port)
+ wait(task)
+ catch e
+ if e isa InterruptException
+ @info "exited"
+ else
+ rethrow(e)
+ end
+
+ end
+ end
+ start_server = () -> begin
+ handler = make_handler(app);
+ server = Sockets.listen(get_inetaddr(host, port))
+ task = @async HTTP.serve(handler, host, port; server = server)
+ @info string("Running on http://", host, ":", port)
+ return (server, task)
+ end
 
+ if get_devsetting(app, :hot_reload) && !is_hot_restart_available()
+ @warn "Hot reloading is disabled for interactive sessions. Please run your app using julia from the command line to take advantage of this feature."
+ end
+
+ if get_devsetting(app, :hot_reload) && is_hot_restart_available()
+ hot_restart(start_server, check_interval = get_devsetting(app, :hot_reload_watch_interval))
+ else
+ (server, task) = start_server()
+ try
+ wait(task)
+ println(task)
+ catch e
+ close(server)
+ if e isa InterruptException 
+ println("finished")
+ return
+ else
+ rethrow(e)
+ end
+ end
+ end
+end
+get_inetaddr(host::String, port::Integer) = Sockets.InetAddr(parse(IPAddr, host), port)
+get_inetaddr(host::IPAddr, port::Integer) = Sockets.InetAddr(host, port)
 
 end # module
diff --git a/src/app/callbacks.jl b/src/app/callbacks.jl
@@ -19,7 +19,7 @@ Create a callback that updates the output by calling function `func`.
 # Examples
 
 ```julia
-app = dash("Test") do
+app = dash() do
  html_div() do
  dcc_input(id="graphTitle", value="Let's Dance!", type = "text"),
  dcc_input(id="graphTitle2", value="Let's Dance!", type = "text"),

diff --git a/src/app/dashapp.jl b/src/app/dashapp.jl
@@ -25,14 +25,16 @@ Dash.jl's internal representation of a Dash application.
 This `struct` is not intended to be called directly; developers should create their Dash application using the `dash` function instead.
 """
 mutable struct DashApp
- name ::String
+ root_path ::String
+ is_interactive ::Bool
  config ::DashConfig
  index_string ::Union{String, Nothing}
+ title ::String
  layout ::Union{Nothing, Component, Function}
  devtools ::DevTools
  callbacks ::Dict{Symbol, Callback}
 
- DashApp(name, config, index_string) = new(name, config, index_string, nothing, DevTools(dash_env(Bool, "debug", false)), Dict{Symbol, Callback}())
+ DashApp(root_path, is_interactive, config, index_string, title = "Dash") = new(root_path, is_interactive, config, index_string, title, nothing, DevTools(dash_env(Bool, "debug", false)), Dict{Symbol, Callback}())
 
 end
 
@@ -41,6 +43,7 @@ function Base.setproperty!(app::DashApp, property::Symbol, value)
  property == :name && return set_name!(app, value)
  property == :index_string && return set_index_string!(app, value)
  property == :layout && return set_layout!(app::DashApp, value)
+ property == :title && return set_title!(app::DashApp, value)
 
  property in fieldnames(DashApp) && error("The property `$(property)` of `DashApp` is read-only")
 
@@ -51,6 +54,10 @@ function set_name!(app::DashApp, name)
  setfield!(app, :name, name)
 end
 
+function set_title!(app::DashApp, title)
+ setfield!(app, :title, title)
+end
+
 get_name(app::DashApp) = app.name
 
 function set_layout!(app::DashApp, component::Union{Component,Function})
@@ -106,6 +113,8 @@ get_devsetting(app::DashApp, name::Symbol) = getproperty(app.devtools, name)
 
 get_setting(app::DashApp, name::Symbol) = getproperty(app.config, name)
 
+get_assets_path(app::DashApp) = joinpath(app.root_path, get_setting(app, :assets_folder))
+
 """
  dash(name::String;
  external_stylesheets,
@@ -134,7 +143,6 @@ If a parameter can be set by an environment variable, that is listed as:
  Values provided here take precedence over environment variables.
 
 # Arguments
-- `name::String` - The name of your application
 - `assets_folder::String` - a path, relative to the current working directory,
  for extra files to be used in the browser. Default `'assets'`. All .js and .css files will be loaded immediately unless excluded by `assets_ignore`, and other files such as images will be served if requested.
 
@@ -212,7 +220,7 @@ If a parameter can be set by an environment variable, that is listed as:
  files and data served by HTTP.jl when supported by the client. Set to
  ``false`` to disable compression completely.
 """
-function dash(name::String = dash_env("dash_name", "");
+function dash(;
  external_stylesheets = ExternalSrcType[],
  external_scripts = ExternalSrcType[],
  url_base_pathname = dash_env("url_base_pathname"), 
@@ -242,7 +250,7 @@ function dash(name::String = dash_env("dash_name", "");
  requests_pathname_prefix,
  routes_pathname_prefix
  )...,
-absolute_assets_path(assets_folder),
+ assets_folder,
  lstrip(assets_url_path, '/'),
  assets_ignore, 
  serve_locally, 
@@ -254,6 +262,6 @@ function dash(name::String = dash_env("dash_name", "");
  show_undo_redo,
  compress
  )
- result = DashApp(name, config, index_string)
+ result = DashApp(app_root_path(), isinteractive(), config, index_string)
  return result
-end
+end
diff --git a/src/app/devtools.jl b/src/app/devtools.jl
@@ -3,8 +3,8 @@ struct DevTools
  props_check::Bool
  serve_dev_bundles::Bool
  hot_reload::Bool
- hot_reload_interval::Float32
- hot_reload_watch_interval::Float32
+ hot_reload_interval::Float64
+ hot_reload_watch_interval::Float64
  hot_reload_max_retry::Int
  silence_routes_logging::Bool
  prune_errors::Bool

diff --git a/src/handler/handlers.jl b/src/handler/handlers.jl
@@ -18,6 +18,7 @@ function process_dependencies(request::HTTP.Request, state::HandlerState)
 end
 
 function process_index(request::HTTP.Request, state::HandlerState)
+ get_cache(state).need_recache && rebuild_cache!(state)
  return HTTP.Response(
  200,
  ["Content-Type" => "text/html"],
@@ -147,7 +148,7 @@ end
 
 function process_assets(request::HTTP.Request, state::HandlerState; file_path::AbstractString)
  app = state.app
- filename = joinpath(get_setting(app, :assets_folder), file_path)
+ filename = joinpath(get_assets_path(app), file_path)
 
  try
  headers = Pair{String,String}[]
@@ -161,7 +162,47 @@ function process_assets(request::HTTP.Request, state::HandlerState; file_path::A
 
 end
 
-const dash_router = HTTP.Router()
+function process_reload_hash(request::HTTP.Request, state::HandlerState)
+ reload_tuple = (
+ reloadHash = state.reload.hash,
+ hard = state.reload.hard,
+ packages = keys(state.cache.resources.files),
+ files = state.reload.changed_assets
+ ) 
+ state.reload.hard = false
+ state.reload.changed_assets = []
+ return HTTP.Response(200, ["Content-Type" => "application/json"], body = JSON2.write(reload_tuple))
+
+end
+
+function start_reload_poll(state::HandlerState)
+ folders = Set{String}()
+ push!(folders, get_assets_path(state.app))
+ push!(folders, state.registry.dash_renderer.path)
+ for pkg in values(state.registry.components)
+ push!(folders, pkg.path)
+ end
+ state.reload.task = @async poll_folders(folders; interval = get_devsetting(state.app, :hot_reload_watch_interval)) do file, ts, deleted
+ state.reload.hard = true
+ state.reload.hash = generate_hash()
+ assets_path = get_assets_path(state.app)
+ if startswith(file, assets_path)
+ state.cache.need_recache = true
+ rel_path = lstrip(
+ replace(relpath(file, assets_path), '\\'=>'/'),
+ '/'
+ )
+ push!(state.reload.changed_assets, 
+ ChangedAsset(
+ asset_path(state.app, rel_path), 
+ trunc(Int, ts),
+ endswith(file, "css")
+ )
+ )
+ end
+
+ end
+end
 
 validate_layout(layout::Component) = validate(layout)
 
@@ -180,6 +221,7 @@ function make_handler(app::DashApp, registry::ResourcesRegistry; check_layout =
  router = Router()
  add_route!(process_layout, router, "$(prefix)_dash-layout")
  add_route!(process_dependencies, router, "$(prefix)_dash-dependencies")
+ add_route!(process_reload_hash, router, "$(prefix)_reload-hash")
  add_route!(process_resource, router, "$(prefix)_dash-component-suites/<namespace>/<path>")
  add_route!(process_assets, router, "$(prefix)$(assets_url_path)/<file_path>")
  add_route!(process_callback, router, "POST", "$(prefix)_dash-update-component")
@@ -189,7 +231,12 @@ function make_handler(app::DashApp, registry::ResourcesRegistry; check_layout =
  handler = state_handler(router, state)
  get_setting(app, :compress) && (handler = compress_handler(handler))
 
- HTTP.handle(handler, HTTP.Request("GET", prefix)) #For handler precompilation
+ compile_request = HTTP.Request("GET", prefix)
+ HTTP.setheader(compile_request, "Accept-Encoding" => "gzip")
+ HTTP.handle(handler, compile_request) #For handler precompilation
+
+ get_devsetting(app, :hot_reload) && start_reload_poll(state)
+
  return handler
 end
 

diff --git a/src/handler/index_page.jl b/src/handler/index_page.jl
@@ -99,7 +99,7 @@ function index_page(app::DashApp, resources::ApplicationResources)
 
  result = interpolate_string(app.index_string,
  metas = metas_html(app),
- title = app.name,
+ title = app.title,
  favicon = favicon_html(app),
  css = css_html(app, resources),
  app_entry = app_entry_html(),

diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -3,6 +3,7 @@ All notable changes to this project will be documented in this file. This projec
 
 ### [UNRELEASED]
 ### Added
+- Support for hot reloading on application or asset changes [#25](plotly/Dash.jl#25)
 - Asset serving of CSS, JavaScript, and other resources [#18](plotly/Dash.jl#18)
 - Support for passing functions as layouts [#18](plotly/Dash.jl#18)
 - Resource registry for component assets [#18](plotly/Dash.jl#18)

diff --git a/Project.toml b/Project.toml
@@ -13,7 +13,9 @@ LibGit2 = "76f85450-5226-5b5a-8eaa-529ad045b433"
 MD5 = "6ac74813-4b46-53a4-afec-0b5dc9d7885c"
 MacroTools = "1914dd2f-81c6-5fcd-8719-6d5c9610ff09"
 PlotlyBase = "a03496cd-edff-5a9b-9e67-9cda94a718b5"
+Sockets = "6462fe0b-24de-5631-8697-dd941f90decc"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
+UUIDs = "cf7118a7-6976-5b1a-9a39-7adc72f591a4"
 
 [compat]
 DataStructures = "0.17.5"

diff --git a/README.md b/README.md
@@ -21,7 +21,7 @@ import Pkg; Pkg.add(Pkg.PackageSpec(url = "https://github.com/plotly/Dash.jl.git
 
 ```jldoctest
 julia> using Dash
-julia> app = dash("Test app", external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"])
+julia> app = dash(external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"])
 
 julia> app.layout = html_div() do
  html_h1("Hello Dash"),
@@ -55,7 +55,7 @@ __Once you have run the code to create the Dashboard, go to `http://127.0.0.1:80
 ```jldoctest
 
 julia> using Dash
-julia> app = dash("Test app", external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"])
+julia> app = dash(external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"])
 
 julia> app.layout = html_div() do
  dcc_input(id = "my-id", value="initial value", type = "text"),
@@ -76,7 +76,7 @@ julia> run_server(app, "0.0.0.0", 8080)
 ### States and Multiple Outputs
 ```jldoctest
 julia> using Dash
-julia> app = dash("Test app", external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"])
+julia> app = dash(external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"])
 
 julia> app.layout = html_div() do
  dcc_input(id = "my-id", value="initial value", type = "text"),

diff --git a/docs/src/index.md b/docs/src/index.md
@@ -33,7 +33,7 @@ import Pkg; Pkg.add("Dashboards")
 ```jldoctest
 julia> import HTTP
 julia> using Dashboards
-julia> app = Dash("Test app", external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
+julia> app = Dash(external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
  html_div() do
  html_h1("Hello Dashboards"),
  html_div("Dashboards: Julia interface for Dash"),
@@ -68,7 +68,7 @@ __Once you have run the code to create the Dashboard, go to `http://127.0.0.1:80
 ```jldoctest
 julia> import HTTP
 julia> using Dashboards
-julia> app = Dash("Test app", external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
+julia> app = Dash(external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
  html_div() do
  dcc_input(id = "my-id", value="initial value", type = "text"),
  html_div(id = "my-div") 
@@ -89,7 +89,7 @@ julia> HTTP.serve(handler, HTTP.Sockets.localhost, 8080)
 ```jldoctest
 julia> import HTTP
 julia> using Dashboards
-julia> app = Dash("Test app", external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
+julia> app = Dash(external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
  html_div() do
  dcc_input(id = "my-id", value="initial value", type = "text"),
  html_div(id = "my-div"),

diff --git a/src/Dash.jl b/src/Dash.jl
@@ -1,5 +1,6 @@
 module Dash
 import HTTP, JSON2, CodecZlib, MD5
+using Sockets
 using MacroTools
 const ROOT_PATH = realpath(joinpath(@__DIR__, ".."))
 include("Components.jl")
@@ -19,7 +20,6 @@ include("utils.jl")
 include("app.jl")
 include("resources/registry.jl")
 include("resources/application.jl")
-include("config.jl")
 include("handlers.jl")
 
 @doc """
@@ -31,7 +31,7 @@ Julia backend for [Plotly Dash](https://github.com/plotly/dash)
 ```julia
 
 using Dash
-app = dash("Test", external_stylesheets=["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
+app = dash(external_stylesheets=["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
  html_div() do
  dcc_input(id="graphTitle", value="Let's Dance!", type = "text"),
  html_div(id="outputID"), 
@@ -76,7 +76,7 @@ Run Dash server
 
 #Examples
 ```jldoctest
-julia> app = dash("Test") do
+julia> app = dash() do
  html_div() do
  html_h1("Test Dashboard")
  end
@@ -111,10 +111,53 @@ function run_server(app::DashApp, host = HTTP.Sockets.localhost, port = 8050;
  dev_tools_silence_routes_logging = dev_tools_silence_routes_logging,
  dev_tools_prune_errors = dev_tools_prune_errors
  )
- handler = make_handler(app);
- @info string("Running on http://", host, ":", port)
- HTTP.serve(handler, host, port)
-end
+ main_func = () -> begin
+ ccall(:jl_exit_on_sigint, Cvoid, (Cint,), 0)
+ handler = make_handler(app);
+ try
+ task = @async HTTP.serve(handler, host, port)
+ @info string("Running on http://", host, ":", port)
+ wait(task)
+ catch e
+ if e isa InterruptException
+ @info "exited"
+ else
+ rethrow(e)
+ end
+
+ end
+ end
+ start_server = () -> begin
+ handler = make_handler(app);
+ server = Sockets.listen(get_inetaddr(host, port))
+ task = @async HTTP.serve(handler, host, port; server = server)
+ @info string("Running on http://", host, ":", port)
+ return (server, task)
+ end
 
+ if get_devsetting(app, :hot_reload) && !is_hot_restart_available()
+ @warn "Hot reloading is disabled for interactive sessions. Please run your app using julia from the command line to take advantage of this feature."
+ end
+
+ if get_devsetting(app, :hot_reload) && is_hot_restart_available()
+ hot_restart(start_server, check_interval = get_devsetting(app, :hot_reload_watch_interval))
+ else
+ (server, task) = start_server()
+ try
+ wait(task)
+ println(task)
+ catch e
+ close(server)
+ if e isa InterruptException 
+ println("finished")
+ return
+ else
+ rethrow(e)
+ end
+ end
+ end
+end
+get_inetaddr(host::String, port::Integer) = Sockets.InetAddr(parse(IPAddr, host), port)
+get_inetaddr(host::IPAddr, port::Integer) = Sockets.InetAddr(host, port)
 
 end # module
diff --git a/src/app/callbacks.jl b/src/app/callbacks.jl
@@ -19,7 +19,7 @@ Create a callback that updates the output by calling function `func`.
 # Examples
 
 ```julia
-app = dash("Test") do
+app = dash() do
  html_div() do
  dcc_input(id="graphTitle", value="Let's Dance!", type = "text"),
  dcc_input(id="graphTitle2", value="Let's Dance!", type = "text"),

diff --git a/src/app/dashapp.jl b/src/app/dashapp.jl
@@ -25,14 +25,16 @@ Dash.jl's internal representation of a Dash application.
 This `struct` is not intended to be called directly; developers should create their Dash application using the `dash` function instead.
 """
 mutable struct DashApp
- name ::String
+ root_path ::String
+ is_interactive ::Bool
  config ::DashConfig
  index_string ::Union{String, Nothing}
+ title ::String
  layout ::Union{Nothing, Component, Function}
  devtools ::DevTools
  callbacks ::Dict{Symbol, Callback}
 
- DashApp(name, config, index_string) = new(name, config, index_string, nothing, DevTools(dash_env(Bool, "debug", false)), Dict{Symbol, Callback}())
+ DashApp(root_path, is_interactive, config, index_string, title = "Dash") = new(root_path, is_interactive, config, index_string, title, nothing, DevTools(dash_env(Bool, "debug", false)), Dict{Symbol, Callback}())
 
 end
 
@@ -41,6 +43,7 @@ function Base.setproperty!(app::DashApp, property::Symbol, value)
  property == :name && return set_name!(app, value)
  property == :index_string && return set_index_string!(app, value)
  property == :layout && return set_layout!(app::DashApp, value)
+ property == :title && return set_title!(app::DashApp, value)
 
  property in fieldnames(DashApp) && error("The property `$(property)` of `DashApp` is read-only")
 
@@ -51,6 +54,10 @@ function set_name!(app::DashApp, name)
  setfield!(app, :name, name)
 end
 
+function set_title!(app::DashApp, title)
+ setfield!(app, :title, title)
+end
+
 get_name(app::DashApp) = app.name
 
 function set_layout!(app::DashApp, component::Union{Component,Function})
@@ -106,6 +113,8 @@ get_devsetting(app::DashApp, name::Symbol) = getproperty(app.devtools, name)
 
 get_setting(app::DashApp, name::Symbol) = getproperty(app.config, name)
 
+get_assets_path(app::DashApp) = joinpath(app.root_path, get_setting(app, :assets_folder))
+
 """
  dash(name::String;
  external_stylesheets,
@@ -134,7 +143,6 @@ If a parameter can be set by an environment variable, that is listed as:
  Values provided here take precedence over environment variables.
 
 # Arguments
-- `name::String` - The name of your application
 - `assets_folder::String` - a path, relative to the current working directory,
  for extra files to be used in the browser. Default `'assets'`. All .js and .css files will be loaded immediately unless excluded by `assets_ignore`, and other files such as images will be served if requested.
 
@@ -212,7 +220,7 @@ If a parameter can be set by an environment variable, that is listed as:
  files and data served by HTTP.jl when supported by the client. Set to
  ``false`` to disable compression completely.
 """
-function dash(name::String = dash_env("dash_name", "");
+function dash(;
  external_stylesheets = ExternalSrcType[],
  external_scripts = ExternalSrcType[],
  url_base_pathname = dash_env("url_base_pathname"), 
@@ -242,7 +250,7 @@ function dash(name::String = dash_env("dash_name", "");
  requests_pathname_prefix,
  routes_pathname_prefix
  )...,
-absolute_assets_path(assets_folder),
+ assets_folder,
  lstrip(assets_url_path, '/'),
  assets_ignore, 
  serve_locally, 
@@ -254,6 +262,6 @@ function dash(name::String = dash_env("dash_name", "");
  show_undo_redo,
  compress
  )
- result = DashApp(name, config, index_string)
+ result = DashApp(app_root_path(), isinteractive(), config, index_string)
  return result
-end
+end
diff --git a/src/app/devtools.jl b/src/app/devtools.jl
@@ -3,8 +3,8 @@ struct DevTools
  props_check::Bool
  serve_dev_bundles::Bool
  hot_reload::Bool
- hot_reload_interval::Float32
- hot_reload_watch_interval::Float32
+ hot_reload_interval::Float64
+ hot_reload_watch_interval::Float64
  hot_reload_max_retry::Int
  silence_routes_logging::Bool
  prune_errors::Bool

diff --git a/src/handler/handlers.jl b/src/handler/handlers.jl
@@ -18,6 +18,7 @@ function process_dependencies(request::HTTP.Request, state::HandlerState)
 end
 
 function process_index(request::HTTP.Request, state::HandlerState)
+ get_cache(state).need_recache && rebuild_cache!(state)
  return HTTP.Response(
  200,
  ["Content-Type" => "text/html"],
@@ -147,7 +148,7 @@ end
 
 function process_assets(request::HTTP.Request, state::HandlerState; file_path::AbstractString)
  app = state.app
- filename = joinpath(get_setting(app, :assets_folder), file_path)
+ filename = joinpath(get_assets_path(app), file_path)
 
  try
  headers = Pair{String,String}[]
@@ -161,7 +162,47 @@ function process_assets(request::HTTP.Request, state::HandlerState; file_path::A
 
 end
 
-const dash_router = HTTP.Router()
+function process_reload_hash(request::HTTP.Request, state::HandlerState)
+ reload_tuple = (
+ reloadHash = state.reload.hash,
+ hard = state.reload.hard,
+ packages = keys(state.cache.resources.files),
+ files = state.reload.changed_assets
+ ) 
+ state.reload.hard = false
+ state.reload.changed_assets = []
+ return HTTP.Response(200, ["Content-Type" => "application/json"], body = JSON2.write(reload_tuple))
+
+end
+
+function start_reload_poll(state::HandlerState)
+ folders = Set{String}()
+ push!(folders, get_assets_path(state.app))
+ push!(folders, state.registry.dash_renderer.path)
+ for pkg in values(state.registry.components)
+ push!(folders, pkg.path)
+ end
+ state.reload.task = @async poll_folders(folders; interval = get_devsetting(state.app, :hot_reload_watch_interval)) do file, ts, deleted
+ state.reload.hard = true
+ state.reload.hash = generate_hash()
+ assets_path = get_assets_path(state.app)
+ if startswith(file, assets_path)
+ state.cache.need_recache = true
+ rel_path = lstrip(
+ replace(relpath(file, assets_path), '\\'=>'/'),
+ '/'
+ )
+ push!(state.reload.changed_assets, 
+ ChangedAsset(
+ asset_path(state.app, rel_path), 
+ trunc(Int, ts),
+ endswith(file, "css")
+ )
+ )
+ end
+
+ end
+end
 
 validate_layout(layout::Component) = validate(layout)
 
@@ -180,6 +221,7 @@ function make_handler(app::DashApp, registry::ResourcesRegistry; check_layout =
  router = Router()
  add_route!(process_layout, router, "$(prefix)_dash-layout")
  add_route!(process_dependencies, router, "$(prefix)_dash-dependencies")
+ add_route!(process_reload_hash, router, "$(prefix)_reload-hash")
  add_route!(process_resource, router, "$(prefix)_dash-component-suites/<namespace>/<path>")
  add_route!(process_assets, router, "$(prefix)$(assets_url_path)/<file_path>")
  add_route!(process_callback, router, "POST", "$(prefix)_dash-update-component")
@@ -189,7 +231,12 @@ function make_handler(app::DashApp, registry::ResourcesRegistry; check_layout =
  handler = state_handler(router, state)
  get_setting(app, :compress) && (handler = compress_handler(handler))
 
- HTTP.handle(handler, HTTP.Request("GET", prefix)) #For handler precompilation
+ compile_request = HTTP.Request("GET", prefix)
+ HTTP.setheader(compile_request, "Accept-Encoding" => "gzip")
+ HTTP.handle(handler, compile_request) #For handler precompilation
+
+ get_devsetting(app, :hot_reload) && start_reload_poll(state)
+
  return handler
 end
 

diff --git a/src/handler/index_page.jl b/src/handler/index_page.jl
@@ -99,7 +99,7 @@ function index_page(app::DashApp, resources::ApplicationResources)
 
  result = interpolate_string(app.index_string,
  metas = metas_html(app),
- title = app.name,
+ title = app.title,
  favicon = favicon_html(app),
  css = css_html(app, resources),
  app_entry = app_entry_html(),

diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -3,6 +3,7 @@ All notable changes to this project will be documented in this file. This projec
 
 ### [UNRELEASED]
 ### Added
+- Support for hot reloading on application or asset changes [#25](plotly/Dash.jl#25)
 - Asset serving of CSS, JavaScript, and other resources [#18](plotly/Dash.jl#18)
 - Support for passing functions as layouts [#18](plotly/Dash.jl#18)
 - Resource registry for component assets [#18](plotly/Dash.jl#18)

diff --git a/Project.toml b/Project.toml
@@ -13,7 +13,9 @@ LibGit2 = "76f85450-5226-5b5a-8eaa-529ad045b433"
 MD5 = "6ac74813-4b46-53a4-afec-0b5dc9d7885c"
 MacroTools = "1914dd2f-81c6-5fcd-8719-6d5c9610ff09"
 PlotlyBase = "a03496cd-edff-5a9b-9e67-9cda94a718b5"
+Sockets = "6462fe0b-24de-5631-8697-dd941f90decc"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
+UUIDs = "cf7118a7-6976-5b1a-9a39-7adc72f591a4"
 
 [compat]
 DataStructures = "0.17.5"

diff --git a/README.md b/README.md
@@ -21,7 +21,7 @@ import Pkg; Pkg.add(Pkg.PackageSpec(url = "https://github.com/plotly/Dash.jl.git
 
 ```jldoctest
 julia> using Dash
-julia> app = dash("Test app", external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"])
+julia> app = dash(external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"])
 
 julia> app.layout = html_div() do
  html_h1("Hello Dash"),
@@ -55,7 +55,7 @@ __Once you have run the code to create the Dashboard, go to `http://127.0.0.1:80
 ```jldoctest
 
 julia> using Dash
-julia> app = dash("Test app", external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"])
+julia> app = dash(external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"])
 
 julia> app.layout = html_div() do
  dcc_input(id = "my-id", value="initial value", type = "text"),
@@ -76,7 +76,7 @@ julia> run_server(app, "0.0.0.0", 8080)
 ### States and Multiple Outputs
 ```jldoctest
 julia> using Dash
-julia> app = dash("Test app", external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"])
+julia> app = dash(external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"])
 
 julia> app.layout = html_div() do
  dcc_input(id = "my-id", value="initial value", type = "text"),

diff --git a/docs/src/index.md b/docs/src/index.md
@@ -33,7 +33,7 @@ import Pkg; Pkg.add("Dashboards")
 ```jldoctest
 julia> import HTTP
 julia> using Dashboards
-julia> app = Dash("Test app", external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
+julia> app = Dash(external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
  html_div() do
  html_h1("Hello Dashboards"),
  html_div("Dashboards: Julia interface for Dash"),
@@ -68,7 +68,7 @@ __Once you have run the code to create the Dashboard, go to `http://127.0.0.1:80
 ```jldoctest
 julia> import HTTP
 julia> using Dashboards
-julia> app = Dash("Test app", external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
+julia> app = Dash(external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
  html_div() do
  dcc_input(id = "my-id", value="initial value", type = "text"),
  html_div(id = "my-div") 
@@ -89,7 +89,7 @@ julia> HTTP.serve(handler, HTTP.Sockets.localhost, 8080)
 ```jldoctest
 julia> import HTTP
 julia> using Dashboards
-julia> app = Dash("Test app", external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
+julia> app = Dash(external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
  html_div() do
  dcc_input(id = "my-id", value="initial value", type = "text"),
  html_div(id = "my-div"),

diff --git a/src/Dash.jl b/src/Dash.jl
@@ -1,5 +1,6 @@
 module Dash
 import HTTP, JSON2, CodecZlib, MD5
+using Sockets
 using MacroTools
 const ROOT_PATH = realpath(joinpath(@__DIR__, ".."))
 include("Components.jl")
@@ -19,7 +20,6 @@ include("utils.jl")
 include("app.jl")
 include("resources/registry.jl")
 include("resources/application.jl")
-include("config.jl")
 include("handlers.jl")
 
 @doc """
@@ -31,7 +31,7 @@ Julia backend for [Plotly Dash](https://github.com/plotly/dash)
 ```julia
 
 using Dash
-app = dash("Test", external_stylesheets=["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
+app = dash(external_stylesheets=["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
  html_div() do
  dcc_input(id="graphTitle", value="Let's Dance!", type = "text"),
  html_div(id="outputID"), 
@@ -76,7 +76,7 @@ Run Dash server
 
 #Examples
 ```jldoctest
-julia> app = dash("Test") do
+julia> app = dash() do
  html_div() do
  html_h1("Test Dashboard")
  end
@@ -111,10 +111,53 @@ function run_server(app::DashApp, host = HTTP.Sockets.localhost, port = 8050;
  dev_tools_silence_routes_logging = dev_tools_silence_routes_logging,
  dev_tools_prune_errors = dev_tools_prune_errors
  )
- handler = make_handler(app);
- @info string("Running on http://", host, ":", port)
- HTTP.serve(handler, host, port)
-end
+ main_func = () -> begin
+ ccall(:jl_exit_on_sigint, Cvoid, (Cint,), 0)
+ handler = make_handler(app);
+ try
+ task = @async HTTP.serve(handler, host, port)
+ @info string("Running on http://", host, ":", port)
+ wait(task)
+ catch e
+ if e isa InterruptException
+ @info "exited"
+ else
+ rethrow(e)
+ end
+
+ end
+ end
+ start_server = () -> begin
+ handler = make_handler(app);
+ server = Sockets.listen(get_inetaddr(host, port))
+ task = @async HTTP.serve(handler, host, port; server = server)
+ @info string("Running on http://", host, ":", port)
+ return (server, task)
+ end
 
+ if get_devsetting(app, :hot_reload) && !is_hot_restart_available()
+ @warn "Hot reloading is disabled for interactive sessions. Please run your app using julia from the command line to take advantage of this feature."
+ end
+
+ if get_devsetting(app, :hot_reload) && is_hot_restart_available()
+ hot_restart(start_server, check_interval = get_devsetting(app, :hot_reload_watch_interval))
+ else
+ (server, task) = start_server()
+ try
+ wait(task)
+ println(task)
+ catch e
+ close(server)
+ if e isa InterruptException 
+ println("finished")
+ return
+ else
+ rethrow(e)
+ end
+ end
+ end
+end
+get_inetaddr(host::String, port::Integer) = Sockets.InetAddr(parse(IPAddr, host), port)
+get_inetaddr(host::IPAddr, port::Integer) = Sockets.InetAddr(host, port)
 
 end # module
diff --git a/src/app/callbacks.jl b/src/app/callbacks.jl
@@ -19,7 +19,7 @@ Create a callback that updates the output by calling function `func`.
 # Examples
 
 ```julia
-app = dash("Test") do
+app = dash() do
  html_div() do
  dcc_input(id="graphTitle", value="Let's Dance!", type = "text"),
  dcc_input(id="graphTitle2", value="Let's Dance!", type = "text"),

diff --git a/src/app/dashapp.jl b/src/app/dashapp.jl
@@ -25,14 +25,16 @@ Dash.jl's internal representation of a Dash application.
 This `struct` is not intended to be called directly; developers should create their Dash application using the `dash` function instead.
 """
 mutable struct DashApp
- name ::String
+ root_path ::String
+ is_interactive ::Bool
  config ::DashConfig
  index_string ::Union{String, Nothing}
+ title ::String
  layout ::Union{Nothing, Component, Function}
  devtools ::DevTools
  callbacks ::Dict{Symbol, Callback}
 
- DashApp(name, config, index_string) = new(name, config, index_string, nothing, DevTools(dash_env(Bool, "debug", false)), Dict{Symbol, Callback}())
+ DashApp(root_path, is_interactive, config, index_string, title = "Dash") = new(root_path, is_interactive, config, index_string, title, nothing, DevTools(dash_env(Bool, "debug", false)), Dict{Symbol, Callback}())
 
 end
 
@@ -41,6 +43,7 @@ function Base.setproperty!(app::DashApp, property::Symbol, value)
  property == :name && return set_name!(app, value)
  property == :index_string && return set_index_string!(app, value)
  property == :layout && return set_layout!(app::DashApp, value)
+ property == :title && return set_title!(app::DashApp, value)
 
  property in fieldnames(DashApp) && error("The property `$(property)` of `DashApp` is read-only")
 
@@ -51,6 +54,10 @@ function set_name!(app::DashApp, name)
  setfield!(app, :name, name)
 end
 
+function set_title!(app::DashApp, title)
+ setfield!(app, :title, title)
+end
+
 get_name(app::DashApp) = app.name
 
 function set_layout!(app::DashApp, component::Union{Component,Function})
@@ -106,6 +113,8 @@ get_devsetting(app::DashApp, name::Symbol) = getproperty(app.devtools, name)
 
 get_setting(app::DashApp, name::Symbol) = getproperty(app.config, name)
 
+get_assets_path(app::DashApp) = joinpath(app.root_path, get_setting(app, :assets_folder))
+
 """
  dash(name::String;
  external_stylesheets,
@@ -134,7 +143,6 @@ If a parameter can be set by an environment variable, that is listed as:
  Values provided here take precedence over environment variables.
 
 # Arguments
-- `name::String` - The name of your application
 - `assets_folder::String` - a path, relative to the current working directory,
  for extra files to be used in the browser. Default `'assets'`. All .js and .css files will be loaded immediately unless excluded by `assets_ignore`, and other files such as images will be served if requested.
 
@@ -212,7 +220,7 @@ If a parameter can be set by an environment variable, that is listed as:
  files and data served by HTTP.jl when supported by the client. Set to
  ``false`` to disable compression completely.
 """
-function dash(name::String = dash_env("dash_name", "");
+function dash(;
  external_stylesheets = ExternalSrcType[],
  external_scripts = ExternalSrcType[],
  url_base_pathname = dash_env("url_base_pathname"), 
@@ -242,7 +250,7 @@ function dash(name::String = dash_env("dash_name", "");
  requests_pathname_prefix,
  routes_pathname_prefix
  )...,
-absolute_assets_path(assets_folder),
+ assets_folder,
  lstrip(assets_url_path, '/'),
  assets_ignore, 
  serve_locally, 
@@ -254,6 +262,6 @@ function dash(name::String = dash_env("dash_name", "");
  show_undo_redo,
  compress
  )
- result = DashApp(name, config, index_string)
+ result = DashApp(app_root_path(), isinteractive(), config, index_string)
  return result
-end
+end
diff --git a/src/app/devtools.jl b/src/app/devtools.jl
@@ -3,8 +3,8 @@ struct DevTools
  props_check::Bool
  serve_dev_bundles::Bool
  hot_reload::Bool
- hot_reload_interval::Float32
- hot_reload_watch_interval::Float32
+ hot_reload_interval::Float64
+ hot_reload_watch_interval::Float64
  hot_reload_max_retry::Int
  silence_routes_logging::Bool
  prune_errors::Bool

diff --git a/src/handler/handlers.jl b/src/handler/handlers.jl
@@ -18,6 +18,7 @@ function process_dependencies(request::HTTP.Request, state::HandlerState)
 end
 
 function process_index(request::HTTP.Request, state::HandlerState)
+ get_cache(state).need_recache && rebuild_cache!(state)
  return HTTP.Response(
  200,
  ["Content-Type" => "text/html"],
@@ -147,7 +148,7 @@ end
 
 function process_assets(request::HTTP.Request, state::HandlerState; file_path::AbstractString)
  app = state.app
- filename = joinpath(get_setting(app, :assets_folder), file_path)
+ filename = joinpath(get_assets_path(app), file_path)
 
  try
  headers = Pair{String,String}[]
@@ -161,7 +162,47 @@ function process_assets(request::HTTP.Request, state::HandlerState; file_path::A
 
 end
 
-const dash_router = HTTP.Router()
+function process_reload_hash(request::HTTP.Request, state::HandlerState)
+ reload_tuple = (
+ reloadHash = state.reload.hash,
+ hard = state.reload.hard,
+ packages = keys(state.cache.resources.files),
+ files = state.reload.changed_assets
+ ) 
+ state.reload.hard = false
+ state.reload.changed_assets = []
+ return HTTP.Response(200, ["Content-Type" => "application/json"], body = JSON2.write(reload_tuple))
+
+end
+
+function start_reload_poll(state::HandlerState)
+ folders = Set{String}()
+ push!(folders, get_assets_path(state.app))
+ push!(folders, state.registry.dash_renderer.path)
+ for pkg in values(state.registry.components)
+ push!(folders, pkg.path)
+ end
+ state.reload.task = @async poll_folders(folders; interval = get_devsetting(state.app, :hot_reload_watch_interval)) do file, ts, deleted
+ state.reload.hard = true
+ state.reload.hash = generate_hash()
+ assets_path = get_assets_path(state.app)
+ if startswith(file, assets_path)
+ state.cache.need_recache = true
+ rel_path = lstrip(
+ replace(relpath(file, assets_path), '\\'=>'/'),
+ '/'
+ )
+ push!(state.reload.changed_assets, 
+ ChangedAsset(
+ asset_path(state.app, rel_path), 
+ trunc(Int, ts),
+ endswith(file, "css")
+ )
+ )
+ end
+
+ end
+end
 
 validate_layout(layout::Component) = validate(layout)
 
@@ -180,6 +221,7 @@ function make_handler(app::DashApp, registry::ResourcesRegistry; check_layout =
  router = Router()
  add_route!(process_layout, router, "$(prefix)_dash-layout")
  add_route!(process_dependencies, router, "$(prefix)_dash-dependencies")
+ add_route!(process_reload_hash, router, "$(prefix)_reload-hash")
  add_route!(process_resource, router, "$(prefix)_dash-component-suites/<namespace>/<path>")
  add_route!(process_assets, router, "$(prefix)$(assets_url_path)/<file_path>")
  add_route!(process_callback, router, "POST", "$(prefix)_dash-update-component")
@@ -189,7 +231,12 @@ function make_handler(app::DashApp, registry::ResourcesRegistry; check_layout =
  handler = state_handler(router, state)
  get_setting(app, :compress) && (handler = compress_handler(handler))
 
- HTTP.handle(handler, HTTP.Request("GET", prefix)) #For handler precompilation
+ compile_request = HTTP.Request("GET", prefix)
+ HTTP.setheader(compile_request, "Accept-Encoding" => "gzip")
+ HTTP.handle(handler, compile_request) #For handler precompilation
+
+ get_devsetting(app, :hot_reload) && start_reload_poll(state)
+
  return handler
 end
 

diff --git a/src/handler/index_page.jl b/src/handler/index_page.jl
@@ -99,7 +99,7 @@ function index_page(app::DashApp, resources::ApplicationResources)
 
  result = interpolate_string(app.index_string,
  metas = metas_html(app),
- title = app.name,
+ title = app.title,
  favicon = favicon_html(app),
  css = css_html(app, resources),
  app_entry = app_entry_html(),

diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -3,6 +3,7 @@ All notable changes to this project will be documented in this file. This projec
 
 ### [UNRELEASED]
 ### Added
+- Support for hot reloading on application or asset changes [#25](plotly/Dash.jl#25)
 - Asset serving of CSS, JavaScript, and other resources [#18](plotly/Dash.jl#18)
 - Support for passing functions as layouts [#18](plotly/Dash.jl#18)
 - Resource registry for component assets [#18](plotly/Dash.jl#18)

diff --git a/Project.toml b/Project.toml
@@ -13,7 +13,9 @@ LibGit2 = "76f85450-5226-5b5a-8eaa-529ad045b433"
 MD5 = "6ac74813-4b46-53a4-afec-0b5dc9d7885c"
 MacroTools = "1914dd2f-81c6-5fcd-8719-6d5c9610ff09"
 PlotlyBase = "a03496cd-edff-5a9b-9e67-9cda94a718b5"
+Sockets = "6462fe0b-24de-5631-8697-dd941f90decc"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
+UUIDs = "cf7118a7-6976-5b1a-9a39-7adc72f591a4"
 
 [compat]
 DataStructures = "0.17.5"

diff --git a/README.md b/README.md
@@ -21,7 +21,7 @@ import Pkg; Pkg.add(Pkg.PackageSpec(url = "https://github.com/plotly/Dash.jl.git
 
 ```jldoctest
 julia> using Dash
-julia> app = dash("Test app", external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"])
+julia> app = dash(external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"])
 
 julia> app.layout = html_div() do
  html_h1("Hello Dash"),
@@ -55,7 +55,7 @@ __Once you have run the code to create the Dashboard, go to `http://127.0.0.1:80
 ```jldoctest
 
 julia> using Dash
-julia> app = dash("Test app", external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"])
+julia> app = dash(external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"])
 
 julia> app.layout = html_div() do
  dcc_input(id = "my-id", value="initial value", type = "text"),
@@ -76,7 +76,7 @@ julia> run_server(app, "0.0.0.0", 8080)
 ### States and Multiple Outputs
 ```jldoctest
 julia> using Dash
-julia> app = dash("Test app", external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"])
+julia> app = dash(external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"])
 
 julia> app.layout = html_div() do
  dcc_input(id = "my-id", value="initial value", type = "text"),

diff --git a/docs/src/index.md b/docs/src/index.md
@@ -33,7 +33,7 @@ import Pkg; Pkg.add("Dashboards")
 ```jldoctest
 julia> import HTTP
 julia> using Dashboards
-julia> app = Dash("Test app", external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
+julia> app = Dash(external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
  html_div() do
  html_h1("Hello Dashboards"),
  html_div("Dashboards: Julia interface for Dash"),
@@ -68,7 +68,7 @@ __Once you have run the code to create the Dashboard, go to `http://127.0.0.1:80
 ```jldoctest
 julia> import HTTP
 julia> using Dashboards
-julia> app = Dash("Test app", external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
+julia> app = Dash(external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
  html_div() do
  dcc_input(id = "my-id", value="initial value", type = "text"),
  html_div(id = "my-div") 
@@ -89,7 +89,7 @@ julia> HTTP.serve(handler, HTTP.Sockets.localhost, 8080)
 ```jldoctest
 julia> import HTTP
 julia> using Dashboards
-julia> app = Dash("Test app", external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
+julia> app = Dash(external_stylesheets = ["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
  html_div() do
  dcc_input(id = "my-id", value="initial value", type = "text"),
  html_div(id = "my-div"),

diff --git a/src/Dash.jl b/src/Dash.jl
@@ -1,5 +1,6 @@
 module Dash
 import HTTP, JSON2, CodecZlib, MD5
+using Sockets
 using MacroTools
 const ROOT_PATH = realpath(joinpath(@__DIR__, ".."))
 include("Components.jl")
@@ -19,7 +20,6 @@ include("utils.jl")
 include("app.jl")
 include("resources/registry.jl")
 include("resources/application.jl")
-include("config.jl")
 include("handlers.jl")
 
 @doc """
@@ -31,7 +31,7 @@ Julia backend for [Plotly Dash](https://github.com/plotly/dash)
 ```julia
 
 using Dash
-app = dash("Test", external_stylesheets=["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
+app = dash(external_stylesheets=["https://codepen.io/chriddyp/pen/bWLwgP.css"]) do
  html_div() do
  dcc_input(id="graphTitle", value="Let's Dance!", type = "text"),
  html_div(id="outputID"), 
@@ -76,7 +76,7 @@ Run Dash server
 
 #Examples
 ```jldoctest
-julia> app = dash("Test") do
+julia> app = dash() do
  html_div() do
  html_h1("Test Dashboard")
  end
@@ -111,10 +111,53 @@ function run_server(app::DashApp, host = HTTP.Sockets.localhost, port = 8050;
  dev_tools_silence_routes_logging = dev_tools_silence_routes_logging,
  dev_tools_prune_errors = dev_tools_prune_errors
  )
- handler = make_handler(app);
- @info string("Running on http://", host, ":", port)
- HTTP.serve(handler, host, port)
-end
+ main_func = () -> begin
+ ccall(:jl_exit_on_sigint, Cvoid, (Cint,), 0)
+ handler = make_handler(app);
+ try
+ task = @async HTTP.serve(handler, host, port)
+ @info string("Running on http://", host, ":", port)
+ wait(task)
+ catch e
+ if e isa InterruptException
+ @info "exited"
+ else
+ rethrow(e)
+ end
+
+ end
+ end
+ start_server = () -> begin
+ handler = make_handler(app);
+ server = Sockets.listen(get_inetaddr(host, port))
+ task = @async HTTP.serve(handler, host, port; server = server)
+ @info string("Running on http://", host, ":", port)
+ return (server, task)
+ end
 
+ if get_devsetting(app, :hot_reload) && !is_hot_restart_available()
+ @warn "Hot reloading is disabled for interactive sessions. Please run your app using julia from the command line to take advantage of this feature."
+ end
+
+ if get_devsetting(app, :hot_reload) && is_hot_restart_available()
+ hot_restart(start_server, check_interval = get_devsetting(app, :hot_reload_watch_interval))
+ else
+ (server, task) = start_server()
+ try
+ wait(task)
+ println(task)
+ catch e
+ close(server)
+ if e isa InterruptException 
+ println("finished")
+ return
+ else
+ rethrow(e)
+ end
+ end
+ end
+end
+get_inetaddr(host::String, port::Integer) = Sockets.InetAddr(parse(IPAddr, host), port)
+get_inetaddr(host::IPAddr, port::Integer) = Sockets.InetAddr(host, port)
 
 end # module
diff --git a/src/app/callbacks.jl b/src/app/callbacks.jl
@@ -19,7 +19,7 @@ Create a callback that updates the output by calling function `func`.
 # Examples
 
 ```julia
-app = dash("Test") do
+app = dash() do
  html_div() do
  dcc_input(id="graphTitle", value="Let's Dance!", type = "text"),
  dcc_input(id="graphTitle2", value="Let's Dance!", type = "text"),

diff --git a/src/app/dashapp.jl b/src/app/dashapp.jl
@@ -25,14 +25,16 @@ Dash.jl's internal representation of a Dash application.
 This `struct` is not intended to be called directly; developers should create their Dash application using the `dash` function instead.
 """
 mutable struct DashApp
- name ::String
+ root_path ::String
+ is_interactive ::Bool
  config ::DashConfig
  index_string ::Union{String, Nothing}
+ title ::String
  layout ::Union{Nothing, Component, Function}
  devtools ::DevTools
  callbacks ::Dict{Symbol, Callback}
 
- DashApp(name, config, index_string) = new(name, config, index_string, nothing, DevTools(dash_env(Bool, "debug", false)), Dict{Symbol, Callback}())
+ DashApp(root_path, is_interactive, config, index_string, title = "Dash") = new(root_path, is_interactive, config, index_string, title, nothing, DevTools(dash_env(Bool, "debug", false)), Dict{Symbol, Callback}())
 
 end
 
@@ -41,6 +43,7 @@ function Base.setproperty!(app::DashApp, property::Symbol, value)
  property == :name && return set_name!(app, value)
  property == :index_string && return set_index_string!(app, value)
  property == :layout && return set_layout!(app::DashApp, value)
+ property == :title && return set_title!(app::DashApp, value)
 
  property in fieldnames(DashApp) && error("The property `$(property)` of `DashApp` is read-only")
 
@@ -51,6 +54,10 @@ function set_name!(app::DashApp, name)
  setfield!(app, :name, name)
 end
 
+function set_title!(app::DashApp, title)
+ setfield!(app, :title, title)
+end
+
 get_name(app::DashApp) = app.name
 
 function set_layout!(app::DashApp, component::Union{Component,Function})
@@ -106,6 +113,8 @@ get_devsetting(app::DashApp, name::Symbol) = getproperty(app.devtools, name)
 
 get_setting(app::DashApp, name::Symbol) = getproperty(app.config, name)
 
+get_assets_path(app::DashApp) = joinpath(app.root_path, get_setting(app, :assets_folder))
+
 """
  dash(name::String;
  external_stylesheets,
@@ -134,7 +143,6 @@ If a parameter can be set by an environment variable, that is listed as:
  Values provided here take precedence over environment variables.
 
 # Arguments
-- `name::String` - The name of your application
 - `assets_folder::String` - a path, relative to the current working directory,
  for extra files to be used in the browser. Default `'assets'`. All .js and .css files will be loaded immediately unless excluded by `assets_ignore`, and other files such as images will be served if requested.
 
@@ -212,7 +220,7 @@ If a parameter can be set by an environment variable, that is listed as:
  files and data served by HTTP.jl when supported by the client. Set to
  ``false`` to disable compression completely.
 """
-function dash(name::String = dash_env("dash_name", "");
+function dash(;
  external_stylesheets = ExternalSrcType[],
  external_scripts = ExternalSrcType[],
  url_base_pathname = dash_env("url_base_pathname"), 
@@ -242,7 +250,7 @@ function dash(name::String = dash_env("dash_name", "");
  requests_pathname_prefix,
  routes_pathname_prefix
  )...,
-absolute_assets_path(assets_folder),
+ assets_folder,
  lstrip(assets_url_path, '/'),
  assets_ignore, 
  serve_locally, 
@@ -254,6 +262,6 @@ function dash(name::String = dash_env("dash_name", "");
  show_undo_redo,
  compress
  )
- result = DashApp(name, config, index_string)
+ result = DashApp(app_root_path(), isinteractive(), config, index_string)
  return result
-end
+end
diff --git a/src/app/devtools.jl b/src/app/devtools.jl
@@ -3,8 +3,8 @@ struct DevTools
  props_check::Bool
  serve_dev_bundles::Bool
  hot_reload::Bool
- hot_reload_interval::Float32
- hot_reload_watch_interval::Float32
+ hot_reload_interval::Float64
+ hot_reload_watch_interval::Float64
  hot_reload_max_retry::Int
  silence_routes_logging::Bool
  prune_errors::Bool

diff --git a/src/handler/handlers.jl b/src/handler/handlers.jl
@@ -18,6 +18,7 @@ function process_dependencies(request::HTTP.Request, state::HandlerState)
 end
 
 function process_index(request::HTTP.Request, state::HandlerState)
+ get_cache(state).need_recache && rebuild_cache!(state)
  return HTTP.Response(
  200,
  ["Content-Type" => "text/html"],
@@ -147,7 +148,7 @@ end
 
 function process_assets(request::HTTP.Request, state::HandlerState; file_path::AbstractString)
  app = state.app
- filename = joinpath(get_setting(app, :assets_folder), file_path)
+ filename = joinpath(get_assets_path(app), file_path)
 
  try
  headers = Pair{String,String}[]
@@ -161,7 +162,47 @@ function process_assets(request::HTTP.Request, state::HandlerState; file_path::A
 
 end
 
-const dash_router = HTTP.Router()
+function process_reload_hash(request::HTTP.Request, state::HandlerState)
+ reload_tuple = (
+ reloadHash = state.reload.hash,
+ hard = state.reload.hard,
+ packages = keys(state.cache.resources.files),
+ files = state.reload.changed_assets
+ ) 
+ state.reload.hard = false
+ state.reload.changed_assets = []
+ return HTTP.Response(200, ["Content-Type" => "application/json"], body = JSON2.write(reload_tuple))
+
+end
+
+function start_reload_poll(state::HandlerState)
+ folders = Set{String}()
+ push!(folders, get_assets_path(state.app))
+ push!(folders, state.registry.dash_renderer.path)
+ for pkg in values(state.registry.components)
+ push!(folders, pkg.path)
+ end
+ state.reload.task = @async poll_folders(folders; interval = get_devsetting(state.app, :hot_reload_watch_interval)) do file, ts, deleted
+ state.reload.hard = true
+ state.reload.hash = generate_hash()
+ assets_path = get_assets_path(state.app)
+ if startswith(file, assets_path)
+ state.cache.need_recache = true
+ rel_path = lstrip(
+ replace(relpath(file, assets_path), '\\'=>'/'),
+ '/'
+ )
+ push!(state.reload.changed_assets, 
+ ChangedAsset(
+ asset_path(state.app, rel_path), 
+ trunc(Int, ts),
+ endswith(file, "css")
+ )
+ )
+ end
+
+ end
+end
 
 validate_layout(layout::Component) = validate(layout)
 
@@ -180,6 +221,7 @@ function make_handler(app::DashApp, registry::ResourcesRegistry; check_layout =
  router = Router()
  add_route!(process_layout, router, "$(prefix)_dash-layout")
  add_route!(process_dependencies, router, "$(prefix)_dash-dependencies")
+ add_route!(process_reload_hash, router, "$(prefix)_reload-hash")
  add_route!(process_resource, router, "$(prefix)_dash-component-suites/<namespace>/<path>")
  add_route!(process_assets, router, "$(prefix)$(assets_url_path)/<file_path>")
  add_route!(process_callback, router, "POST", "$(prefix)_dash-update-component")
@@ -189,7 +231,12 @@ function make_handler(app::DashApp, registry::ResourcesRegistry; check_layout =
  handler = state_handler(router, state)
  get_setting(app, :compress) && (handler = compress_handler(handler))
 
- HTTP.handle(handler, HTTP.Request("GET", prefix)) #For handler precompilation
+ compile_request = HTTP.Request("GET", prefix)
+ HTTP.setheader(compile_request, "Accept-Encoding" => "gzip")
+ HTTP.handle(handler, compile_request) #For handler precompilation
+
+ get_devsetting(app, :hot_reload) && start_reload_poll(state)
+
  return handler
 end
 

diff --git a/src/handler/index_page.jl b/src/handler/index_page.jl
@@ -99,7 +99,7 @@ function index_page(app::DashApp, resources::ApplicationResources)
 
  result = interpolate_string(app.index_string,
  metas = metas_html(app),
- title = app.name,
+ title = app.title,
  favicon = favicon_html(app),
  css = css_html(app, resources),
  app_entry = app_entry_html(),