Hypercore-extension that enables two peers to exchange feed keys and descriptors.
Following extension hosts are supported:
- hypercore
- hypercore-protocol
- decentstack (built-in by default)
Take a look at exchange-protocol docs page for a higher level description and sequence diagrams.
Given the following manifest:
// Header-values are allowed to contain primitive types or Buffers// if you want to use a custom encoder/decoderconstmyManifest=[{key: 'deadbeefdeadbeefdeadbeefdeadbeef',headers: {seq: 1,hello: 'world'}},{key: otherKey,headers: {seq: 55,hello: 'planet',title: 'My awesome feed'}}]And given the following handlers Object:
constexchangeHandlers={onmanifest(shared,accept){shared.namespace// => String - 'default'shared.feeds// => Array<Object> - offered keysfor(constfeedoffeeds){// Print the manifest contents.console.log('Remote Shared feed:',feed.key.toString('hex'))console.log('Headers:',feed.headers,'\n')}// `accept` is a Function that directly responds to a given// manifest with `FeedRequest'constacceptedKeys=shared.feeds.filter(...).map(f=>f.key)accept(acceptedKeys)// accept all keys// This is a stub, you should let your replication manager// take care of joining the other feeds into the feed stream.acceptedKeys.forEach(key=>{coreStorage.get(key).replicate(true,{stream: myPeerStream})})},onrequest(req){req.manifest_id// => Number - incrementreq.namespace// => String - 'default'req.keys// => Array - requested keys// Another replication manager stubreq.keys.forEach(key=>{coreStorage.get(key).replicate(false,{stream: myPeerStream})})},onerror(err){throwerr}}Using hypercore-protocol
constProtocol=require('protocol')conststream=newProtocol(true)constext=exchange(stream1,exchangeHandlers)constkey=Buffer.from('deadbeefdeadbeefdeadbeefdeadbeef','hex')constchannel=stream.open(key,{onopen(){ext.sendManifest('default',myManifest,ch1,(err,acceptedKeys)=>{console.log('Remote peer selected',acceptedKeys)})}})Or using vanilla hypercore
consthypercore=require('hypercore')constram=require('random-access-memory')constexchange=require('exchange-protocol')constfeed=hypercore(ram)constext=exchange(feed,exchangeHandlers)feed.on('peer-open',peer=>{// Arguments: namespace, myManifest, target, callbackext.sendManifest('default',manifest,peer,(err,acceptedKeys)=>{// Callback invoked on response from remote peer.// The `requestedKeys` are a copy of `req` param in `onrequest`,// they should be handeled in onrequest.})})Result
In a real world scenario your peer would not be communicating with it self.
But in this example, if we were to send myManifest to the exchangeHandlers the log lines would produce the following output:
> Remote shared feed: deadbeefdeadbeefdeadbeefdeadbeef
> Headers: { seq: 1, hello: 'world' }
>
> Remote shared feed: 1234feed43afdeafa41efeed4124beeb
> Headers: { seq: 55, hello: 'planet', title: 'My awesome feed' }
>
GNU GPLv3