PIGATO
Checkout Grenache , a DHT based high-performance microservices framework for Node.js, Ruby and Go. Supports ZeroMQ and WebSocket transports.
PIGATO - an high-performance Node.js microservices framework based on ZeroMQ
PIGATO aims to offer an high-performance, reliable, scalable and extensible service-oriented framework supporting multiple programming languages: Node.js/Io.js and Ruby.
Supported Programming Languages
- PIGATO : PIGATO Client/Worker/Broker for Node.js / Io.js
- PIGATO-RUBY : PIGATO Client/Worker for Ruby
- PIGATO-GO : PIGATO Client for Go
Structure and Protocol
Actors
- Worker : receives requests, does something and replies. A Worker offers a Service, should be a functionality as atomic as possible
- Client : creates, pushes Requests and waits for results. A request always includes a service name and data for the Worker
- Broker : handles Requests queueing and routing
Benefits
- High-performance
- Realiable, Distributed and Scalable
- Load Balancing
- No central point of failure
- Multi-Worker : infinite Services and infinite Workers for each Service
- Multi-Client : infinite Clients
- Multi-Broker : infinite Brokers to avoid bottlenecks and improve network reliability
Features
- Request / Reply protocol
- Support for partial Replies
- Client concurrent Requests
- Client streaming Requests
- Worker concurrent Requests
- Worker dynamic load balancing
- Client heartbeating for long running requests. Allows Workers to dected whenever Clients disconnect or lose interest in some request. This feature is very useful to stop long-running partial requests (i.e data streaming).
Examples
Start a Broker
node examples/broker
- echo : simple echo request-reply
node examples/echo/worker
node examples/echo/client
- stocks : get stocks data from yahoo
node examples/stocks/worker
node examples/stocks/client
More examples
PIGATO-EXAMPLES : a collection of multi-purpose useful examples.
Performance
PIGATO-PERF : a command-line tool to test PIGATO performances in different scenarios. i
API
Broker
PIGATO.Broker(addr, conf)
-
addr
- Broker address (string, i.e: 'tcp://*:12345') -
conf
- configuration override (type=object, i.e { concurrency: 20 })-
onStart
: function to be called when the Broker start -
onStop
: function to be called when the Broker stop
-
Simply starts up a broker.
var Broker = require('./../index').Broker;
var broker = new Broker("tcp://*:55555");
broker.start(function() {
console.log("Broker started");
});
Events
-
start
: on Client start -
stop
: on Client stop
Worker
PIGATO.Worker(addr, serviceName, conf)
-
addr
- Broker address (type=string, i.e: 'tcp://localhost:12345') -
serviceName
- service implemented by the Worker (type=string, i.e: 'echo')- wildcards * are supported (i.e: 'ech*')
-
conf
- configuration override (type=object, i.e { concurrency: 20 })-
prefix
- sets the Worker identifier prefix -
concurrency
- sets max number of concurrent requests (type=int, -1 = no limit) -
onConnect
: function to be called when the Worker connects to the Broker -
onDisconnnect
: function to be called when the Worker disconnects from the Broker
-
Methods
on
Worker receives request
events with 3 arguments:
-
data
- data sent from the Client (type=string/object/array). -
reply
- extended writable stream (type=object) -
opts
- client request options (type=object)
reply
writable stream exposes also following methods and attributes:
-
write()
- sends partial data to the Client -
end()
- sends last data to the Client and completes/closes current Request -
reject()
- rejects a Request. -
heartbeat()
- forces sending heartbeat to the Broker -
active()
- returns the status of the Request (type=boolean). A Request becomes inactive when the Worker disconnects from the Broker or it has been discarded by the Client or the Client disconnects from the Broker. This is useful for long running tasks so the Worker can monitor whether or not continue processing a Request. -
ended
- tells if the Request has been ended (type=boolean).
Example
var worker = new PIGATO.Worker('tcp://localhost:12345', 'my-service');
worker.start();
worker.on('request', function(data, reply, copts) {
for (var i = 0; i < 1000; i++) {
reply.write('PARTIAL DATA ' + i);
}
reply.end('FINAL DATA');
});
// or
worker.on('request', function(data, reply, copts) {
fs.createReadStream(data).pipe(reply);
});
Worker can change concurrency level updating its configuration. This information is carried with the heartbeat message.
Example
worker.conf.concurrency = 2;
Take note: due to the framing protocol of zmq
only the data supplied to response.end(data)
will be given to the client's final callback.
Events
-
start
: on Worker start -
stop
: on Worker stop -
connect
: on Worker connect -
disconnect
: on Worker disconnect
Client
PIGATO.Client(addr, conf)
-
addr
- Broker address (type=string, i.e: 'tcp://localhost:12345') -
conf
-
prefix
- sets the Client identifier prefix -
autostart
: automatically starts the Client (type=boolean, default=false) -
onConnect
: function to be called when the Client connects to the Broker -
onDisconnnect
: function to be called when the Client disconnects from the Broker
-
Methods
start
Start the Client
request
Send a Request
-
serviceName
- name of the Service we wish to connect to (type=string) -
data
- data to give to the Service (type=string/object/buffer) -
opts
- options for the Request (type=object)-
timeout
: timeout in milliseconds (type=number, default=60000, -1 for infinite timeout) -
retry
: if a Worker dies before replying, the Request is automatically requeued. (type=number, values=0|1, default=0) -
nocache
: skip Broker's cache -
workerId
: ID of the Worker that must handle the Request (type=string)
-
Example
var client = new PIGATO.Client('tcp://localhost:12345');
client.start()
client.request('my-service', { foo: 'bar' }, { timeout: 120000 })
.on('data', function(data) {
console.log("DATA", data);
})
.on('end', function() {
console.log("END");
});
// or
client.request('my-service', 'foo', { timeout: 120000 }).pipe(process.stdout);
Clients may also make request with partial and final callbacks instead of using streams.
serviceName
data
-
partialCallback(err, data)
- called whenever the request does not end but emits data -
finalCallback(err, data)
- called when the request will emit no more data opts
Example
client.request('my-service', 'foo', function (err, data) {
// frames sent prior to final frame
console.log('PARTIAL', data);
}, function (err, data) {
// this is the final frame sent
console.log('FINAL', data);
}, { timeout: 30000 });
Events
-
start
: on Client start -
stop
: on Client stop -
connect
: on Client connect -
disconnect
: on Client disconnect
Core Services
Core services are a set of Services that interact with a Broker via a dedicated PUB/SUB channel to extend its core functionalities.
Initialization
var broker = new PIGATO.Broker(bhost);
var csrv = new PIGATO.services.ExampleCoreService(bhost, {
intch: broker.conf.intch // internal pub/sub channel
});
broker.start();
csrv.start();
Directory
PIGATO.services.Directory
Directory service ($dir) replies to Requests with the list of available Workers for a selected service.
Example
// Broadcast a message to all Workers that offer 'echo' Service
client.request(
'$dir', 'echo', undefined,
function(err, workers) {
workers.forEach(function(wid) {
client.request('echo', 'foo', { workerId: wid });
});
}
);
Notes
- when using a
inproc
socket the broker must become active before any queued messages.
Specification (good for RFC)
- Worker <-> Broker heartbeating.
- Broker tracks Worker/Client/Request relation.
- Client MAY send heartbeat for active request. If the request is being processed by Worker, Broker forwards heartbeat to Worker.
- Worker MAY decide to stop an inactive Request (tracks liveness for Request).
- Client MAY assign a timeout to a Request.
- Worker SHALL NOT send more W_REPLY (for a Request) after sending first W_REPLY message.
- Broker SHALL force disconnect Worker if any error occurs.
Protocol
Common
- Frame 0: Side tag (MDP.CLIENT/MDP.WORKER)
- Frame 1: Message type (MDP.W_REQUEST, MDP.W_REPLY, MDP.W_REPLY_REJECT, ...)
- Frame 2: Service name
- Frame 3: Request ID (uuid)
Client request
- Frame 4: JSON encode request data
- Frame 5: JSON encode request options
Worker reply
- Frame 4: Numeric status (0=OK, -1=ERROR)
- Frame 5: JSON encode request data / error
- Frame 6: JSON encode request options
Changelog
Roadmap
- Add authentication support through zmq-zap ZeroMQ ZAP to trust Clients and Workers.
Follow me
- My personal blog : ardoino.com / @paoloardoino