SILPA Webservice APIs


The old listMethods API call for JSONRPC is not yet implemented in new version see issue #15.


Silpa provides a set of webservice APIs over json-rpc protocol. Silpa services can be used from any programming language which has an RPC implementation. The request and response formats of APIs are in json. It is recommended to read the json-rpc documentation if you are not familiar with that.

This page explains the available usage and sample usage from python application. Implementing this in other programming languages should not be difficult and should be a matter of changing the programming language syntax.

For using the APIs you need the jsonrpc library of python. You can get this from here.


JSON-RPC wraps an object, allowing you to call methods on that object and get the return values. It also provides a way to get error responses. The specification goes into the details (though in a vague sort of way). Here’s the basics:

All access goes through a POST to a single URL.The POST contains a JSON body that looks like

  "method": "methodName",
  "id": "arbitrary-something",
  "params": [arg1, arg2, ...],

The id parameter is just a convenience for the client to keep track of which response goes with which request. This makes asynchronous calls (like an XMLHttpRequest) easier. We just send the exact same id back as we get, we never look at it.

The response is JSON. A successful response looks like

  "result": the_result,
  "error": null,
  "id": "arbitrary-something",

The error response looks like

  "result": null,
  "error": {"name": "JSONRPCError",
  "code": (number 100-999),
  "message": "Some Error Occurred",
  "error": "whatever you want\n(a traceback?)"},
  "id": "arbitrary-something",

It doesn’t seem to indicate if an error response should have a 200 response or a 500 response. So as not to be completely stupid about HTTP, we choose a 500 resonse, as giving an error with a 200 response is irresponsible.


A sample usage using python can be seen below

from jsonrpclib import Server

proxy = Server("")
print proxy.scriptrender.render_text("Some text to render", "svg",

A sample usage using PHP can be seen below

define ('HOSTNAME', '');
$url = HOSTNAME;

// Open the Curl session
$session = curl_init($url);

// If it's a POST, put the POST data in the body
             $postvars = '{"method": "scriptrender.render_text",
             "params": ["Your text goes here", "png", 100,100],
curl_setopt ($session, CURLOPT_POST, true);
curl_setopt ($session, CURLOPT_POSTFIELDS, $postvars);

// Don't return HTTP headers. Do return the contents of the call
curl_setopt($session, CURLOPT_HEADER, false);
curl_setopt($session, CURLOPT_RETURNTRANSFER, true);

// Make the call
$json = curl_exec($session);

// The web service returns json. Set the Content-Type appropriately
header("Content-Type: application/json");
echo $json;
$obj =  json_decode($json,false);
$result  =  $obj->{"result"};
echo $result;