Java and Android Socketcluster Client

Overview

This client provides following functionality

• Support for emitting and listening to remote events
• Automatic reconnection
• Pub/sub
• Authentication (JWT)

License

Apache License, Version 2.0

Gradle

For java

dependencies {
compile 'io.github.sac:SocketclusterClientJava:2.0.0'
}

for sample java examples visit Java Demo

For android

compile ('io.github.sac:SocketclusterClientJava:2.0.0'){
exclude group :'org.json', module: 'json'
}

for sample android demo visit Android Demo

• In case you face any problem while resolving dependencies, you can download jar from here https://dl.bintray.com/sacoo7/Maven/io/github/sac/SocketclusterClientJava/.
• Please report for the issue here #36

Description

Create instance of Socket class by passing url of socketcluster-server end-point

//Create a socket instanceStringurl="ws://localhost:8000/socketcluster/";
Socketsocket = newSocket(url);

Important Note : Default url to socketcluster end-point is always ws://somedomainname.com/socketcluster/.

Registering basic listeners

Implemented using BasicListener interface

socket.setListener(newBasicListener() {
publicvoidonConnected(Socketsocket,Map<String, List<String>> headers) {
System.out.println("Connected to endpoint");
}
publicvoidonDisconnected(Socketsocket,WebSocketFrameserverCloseFrame, WebSocketFrameclientCloseFrame, booleanclosedByServer) {
System.out.println("Disconnected from end-point");
}
publicvoidonConnectError(Socketsocket,WebSocketExceptionexception) {
System.out.println("Got connect error "+ exception);
}
publicvoidonSetAuthToken(Stringtoken, Socketsocket) {
System.out.println("Token is "+ token);
}
publicvoidonAuthentication(Socketsocket,Booleanstatus) {
if (status) {
System.out.println("socket is authenticated");
} else {
System.out.println("Authentication is required (optional)");
}
}
});

Connecting to server

• For connecting to server:

//This will send websocket handshake request to socketcluster-serversocket.connect();

• For connecting asynchronously to server:

//This will send websocket handshake request to socketcluster-serversocket.connectAsync();

• By default reconnection to server is not enabled , to enable it :

//This will set automatic-reconnection to server with delay of 2 seconds and repeating it for 30 timessocket.setReconnection(newReconnectStrategy().setDelay(2000).setMaxAttempts(30));
socket.connect();

• To disable reconnection :

 socket.setReconnection(null); 

• By default logging of messages is enabled ,to disable :

 socket.disableLogging();

Emitting and listening to events

Event emitter

• eventname is name of event and message can be String, boolean, Long or JSON-object

socket.emit(eventname,message);
//socket.emit("chat","Hi");

• To send event with acknowledgement

socket.emit(eventname, message, newAck() {
publicvoidcall(StringeventName,Objecterror, Objectdata) {
//If error and data is StringSystem.out.println("Got message for :"+eventName+" error is :"+error+" data is :"+data);
}
});

Event Listener

• For listening to events :

The object received can be String, Boolean, Long or JSONObject.

socket.on(eventname, newEmitter.Listener() {
publicvoidcall(StringeventName,Objectobject) {
// Cast object to its proper datatypeSystem.out.println("Got message for :"+eventName+" data is :"+data);
}
}); 

• To send acknowledgement back to server

socket.on(eventname, newEmitter.AckListener() {
publicvoidcall(StringeventName,Objectobject, Ackack) {
// Cast object to its proper datatype System.out.println("Got message :: " + object);
/...
Somelogicgoeshere
.../
if (error){
ack.call(eventName,error,null);
}else{
//Data can be of any data typeack.call(eventName,null,data);
}
//Both error and data can be sent to serverack.call(eventName,error,data);
}
});

Implementing Pub-Sub via channels

Creating channel

• For creating and subscribing to channels:

Socket.Channelchannel = socket.createChannel(channelName);
//Socket.Channel channel = socket.createChannel("yolo"); /** * without acknowledgement */channel.subscribe();
/** * with acknowledgement */channel.subscribe(newAck() {
publicvoidcall(StringchannelName, Objecterror, Objectdata) {
if (error == null) {
System.out.println("Subscribed to channel "+channelName+" successfully");
}
}
});

• For getting list of created channels :

List <Socket.Channel> channels=socket.getChannels();

• To get channel by name :

Socket.Channelchannel=socket.getChannelByName("yolo");
//Returns null if channel of given name is not present

Publishing event on channel

• For publishing event :

// message can have any data type/** * without acknowledgement */channel.publish(message);
/** * with acknowledgement */channel.publish(message, newAck() {
publicvoidcall(StringchannelName,Objecterror, Objectdata) {
if (error == null) {
System.out.println("Published message to channel "+channelName+" successfully");
}
}
});

Listening to channel

• For listening to channel event :

channel.onMessage(newEmitter.Listener() {
publicvoidcall(StringchannelName , Objectobject) {
System.out.println("Got message for channel "+channelName+" data is "+data);
}
});

Un-subscribing to channel

/** * without acknowledgement */channel.unsubscribe();
/** * with acknowledgement */channel.unsubscribe(newAck() {
publicvoidcall(StringchannelName, Objecterror, Objectdata) {
if (error == null) {
System.out.println("channel unsubscribed successfully");
}
}
}); 

Handling logging

• Once logger object is received, it is very easy to set internal logging level of library, applying handler for each log messages.
• It can be received using following code

Loggerlogger = socket.getLogger();

• More documentation on handling logging in custom way can be found here http://www.vogella.com/tutorials/Logging/article.html

Handling SSL connection with server

WebSocketFactory class is responsible for creating websocket instances and handling settings with server, for more information visit here

To get instance of WebSocketFactory class :

WebSocketFactoryfactory=socket.getFactorySettings();

The following is an example to set a custom SSL context to a WebSocketFactory instance. (Again, you don't have to call a setSSL* method if you use the default SSL configuration.)

// Create a custom SSL context.SSLContextcontext = NaiveSSLContext.getInstance("TLS");
// Set the custom SSL context.factory.setSSLContext(context);

NaiveSSLContext used in the above example is a factory class to create an SSLContext which naively accepts all certificates without verification. It's enough for testing purposes. When you see an error message "unable to find valid certificate path to requested target" while testing, try NaiveSSLContext.

Setting HTTP proxy with server

If a WebSocket endpoint needs to be accessed via an HTTP proxy, information about the proxy server has to be set to a WebSocketFactory instance before creating a WebSocket instance. Proxy settings are represented by ProxySettings class. A WebSocketFactory instance has an associated ProxySettings instance and it can be obtained by calling WebSocketFactory.getProxySettings() method.

// Get the associated ProxySettings instance.ProxySettingssettings = factory.getProxySettings();

ProxySettings class has methods to set information about a proxy server such as setHost method and setPort method. The following is an example to set a secure (https) proxy server.

// Set a proxy server.settings.setServer("https://proxy.example.com");

If credentials are required for authentication at a proxy server, setId method and setPassword method, or setCredentials method can be used to set the credentials. Note that, however, the current implementation supports only Basic Authentication.

// Set credentials for authentication at a proxy server.settings.setCredentials(id, password);

Star the repo. if you love the client :).