zerorpc
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A port of ZeroRPC to node.js
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zerorpc-node
============
[](https://travis-ci.org/0rpc/zerorpc-node)
ZeroRPC is a communication layer for distributed systems. zerorpc-node is a port of the original [ZeroRPC](https://github.com/0rpc/zerorpc-python) for node.js. We have full client and server support for version 3 of the protocol, and clients/servers written in the Python version can communicate transparently with those written in node.js. This project is in alpha.
To install the package:
Make sure you have [ZeroMQ](https://github.com/zeromq/libzmq) installed.
Then:
```bash
npm install zerorpc
```
If you get the error `Package libzmq was not found` after making sure ZeroMQ is installed, take a look at [the fix for zeromq.node](https://github.com/JustinTulloss/zeromq.node/issues/55). If you get the error `Unable to load shared library <<path to zeromq.node>>/binding.node`, [make sure you run ldconfig](https://github.com/JustinTulloss/zeromq.node/issues/85). If that still doesn't work, check out [this ticket](https://github.com/JustinTulloss/zeromq.node/issues/92).
Servers
-------
To create a new server:
```js
var zerorpc = require("zerorpc");
var server = new zerorpc.Server(context [, heartbeat]);
```
The constructor takes in a context object with the functions to expose
over RPC. Only functions that do not have a leading underscore will be
exposed. Each exposed method must take in a callback as the last
argument. This callback is called as `callback(error, response, more)`
when there is a new update, where error is an error object or string,
response is the new update, and more is a boolean specifying whether new
updates will be available later. `error`, `response`, and `more` default
to falsy values, so e.g. simply calling `callback()` closes an open
stream, since `more` is false by default. Constructor also takes a
heartbeat parameter that specifies the interval that the server should
ping clinets to let them know it is active.
Events:
* `error` - When an error occurs.
Methods:
* `bind(endpoint)` - Binds the server to the specified ZeroMQ endpoint.
* `connect(endpoint)` - Connects the server to the specified ZeroMQ endpoint.
* `close()` - Closes the ZeroMQ socket.
Full example:
```js
var zerorpc = require("zerorpc");
var server = new zerorpc.Server({
addMan: function(sentence, reply) {
reply(null, sentence + ", man!");
},
add42: function(n, reply) {
reply(null, n + 42);
},
iter: function(from, to, step, reply) {
for(i=from; i<to; i+=step) {
reply(null, i, true);
}
reply();
}
});
server.bind("tcp://0.0.0.0:4242");
server.on("error", function(error) {
console.error("RPC server error:", error);
});
```
Clients
-------
To create a new client:
```js
var zerorpc = require("zerorpc");
var client = new zerorpc.Client(options);
```
The constructor optionally takes in an options object. Allowable options:
* `timeout` (number) - Sets the number of seconds to wait for a response before considering the call timed out. Defaults to 30.
* `heartbeatInterval` (number) - Sets the number of miliseconds to send send heartbeats to connected servers. Defaults to 5000ms.
Events:
* `error` - When an error occurs.
Methods:
* `bind(endpoint)` - Binds the client to the specified ZeroMQ endpoint.
* `connect(endpoint)` - Connects the client to the specified ZeroMQ endpoint.
* `close()` - Closes the ZeroMQ socket.
* `invoke(method, arguments..., callback)` - Invokes a remote method.
* `method` is the method name.
* `arguments` are a list of arguments passed to the method, if there are no arguments then this argument is ommitted
* `callback` is a method to call when there is an update. This callback is called as `callback(error, response, more)`, where error is an error object, response is the new update, and more is a boolean specifying whether new updates will be available later (i.e. whether the response is streaming).
Full example:
```js
var zerorpc = require("zerorpc");
var client = new zerorpc.Client();
client.connect("tcp://127.0.0.1:4242");
client.on("error", function(error) {
console.error("RPC client error:", error);
});
client.invoke("iter", 10, 20, 2, function(error, res, more) {
if(error) {
console.error(error);
} else {
console.log("UPDATE:", res);
}
if(!more) {
console.log("Done.");
}
});
```