JSON-RPC 2 for express.
npm install express-jsonrpc2
express-jsonrpc2 is a complete JSON-RPC version 2 server-side implement for express library on node.js.
It's a middleware of express.
``shell`
npm install express-jsonrpc2
`javascript
var path = require('path'),
express = require('express'),
app = express();
var JsonRPC = require('express-jsonrpc2'),
PropTypes = JsonRPC.PropTypes,
_repository = JsonRPC.Repository();
_repository.regsiter({
namespace: 'add',
doc: 'addition of 2 numbers.',
sign: [PropTypes.number, PropTypes.number, PropTypes.number]
}, function (a, b) {
return a + b;
});
app.set('port', (process.env.PORT || 5000));
app.use('/', JsonRPC(_repository));
app.listen(app.get('port'), function () {
console.log('Node app is running on port', app.get('port'));
});
`
Open 'http://localhost:5000' in browser, you will see the Debug page.
On left-side of the page, a serial of available RPC listing in tree view.
Click the 'add', Help, Signature, Parameters for Test will show on the right-side of page.
Input text of '\[1, 2\]', and then click 'execute' button, 3 will show in console of browser.
There are 3 built-on RPC on this RPC server. You can see them on Debug page.
* system.listMethods - This method returns an array of strings, one for each (non-system) method supported by the RPC server.
* system.methodSignature - It returns an array of possible signatures for this method.
* system.methodHelp - It returns a documentation string describing the use of that method.
In case of methods, injectable variable is necessary.
for example, get HTTP request header in RPC,
the request object should be passed when the RPC was invoked.
`javascript`
_repository.regsiter({
namespace: 'injectable',
doc: 'use injectable variable in RPC.',
sign: [PropTypes.object, PropTypes.injectable('request')]
}, function (req) {
return req.headers;
});
By default follow of options are available for injectable:
* request
* session
* response
* repository - the RPC repository.
Some of case, RPC not allow unprivileged call.
Before actually call, permission check mechanism will be triggered.
This function depend on 'perm_check' of injectable parameter,
should implement the perm_check function first.
Once perm_check fail, RPCError(-32604, "Permission denied") will be raised.
About 'perm_check' function, It can as normal function return true/false to make it allow/deny.
It also can return a Promise, resolve true/false or reject(error) to notify check result.
`
mk_injectable(req, res, rpc_repository)
var path = require('path'),
express = require('express'),
app = express();
var JsonRPC = require('express-jsonrpc2'),
PropTypes = JsonRPC.PropTypes,
_repository = JsonRPC.Repository();
_repository.regsiter({
namespace: 'add',
grantTo: ['role1', 'role2'],
doc: 'addition of 2 numbers.',
sign: [PropTypes.number, PropTypes.number, PropTypes.number]
}, function (a, b) {
return a + b;
});
app.set('port', (process.env.PORT || 5000));
app.use('/', JsonRPC(_repository, function getInjectable(req, res, repository) {
return {
request: req,
session: req.session,
response: res,
repository: repository,
perm_check: function(grantTo) { //
var session = req.session;
var userRoles = session.user.roles;
for (var i = 0;i < userRoles.length;i++) {
var role = userRoles[i];
if (grantTo.indexOf(role) !== -1) { // user role is in granted to LIST.
return true;
}
}
return false;
}
}
}));
app.listen(app.get('port'), function () {
console.log('Node app is running on port', app.get('port'));
});
`
| code | message | meaning |
|:-----------------| :-----------------|:------------------------------------------------------------------------------------------------------|
| -32700 | Parse error | Invalid JSON was received by the server. An error occurred on the server while parsing the JSON text. |
| -32600 | Invalid Request | The JSON sent is not a valid Request object. |
| -32601 | Method not found | The method does not exist / is not available. |
| -32602 | Invalid params | Invalid method parameter(s). |
| -32603 | Internal error | Internal JSON-RPC error. |
| -32604 | Permission denied | Injectable 'perm_check' not return/resolve true. |
| -32000 to -32099 | Server error | Reserved for implementation-defined server-errors. |
1. Check out source from Github;
2. Run npm install on source directory;npm run start
3. Run to start the debug server;npm run test` and ensure all test case can be passed.
4. Open 'http://localhost:5000' in browser;
Once fixes or modifies done, should run
Welcome raise issues on Github.