# \[ANN\]: JSON-RPC 1.1 plugin for Rails

**URL:** <https://www.ruby-forum.com/t/ann-json-rpc-1-1-plugin-for-rails/109604>\
**Category:** Rails\
**Created:** [July 17, 2007, 8:16am UTC](https://www.ruby-forum.com/t/ann-json-rpc-1-1-plugin-for-rails/109604 "2007-07-17T08:16:00Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![bodikp](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/e79b87/32.png) [@bodikp](https://www.ruby-forum.com/u/bodikp)\
**Post date:** [July 17, 2007, 8:16am UTC](https://www.ruby-forum.com/t/ann-json-rpc-1-1-plugin-for-rails/109604/1 "2007-07-17T08:16:00Z")

</div>

“json\_rpc” is a complete implementation of the JSON-RPC 1.1 protocol,  
as described in  
the JSON-RPC 1.1 Specification draft, which may be found at  
[http://json-rpc.org/wd/JSON-RPC-1-1-WD-20060807.html](http://json-rpc.org/wd/JSON-RPC-1-1-WD-20060807.html).

JSON-RPC 1.1 is a fast and lightweight text-based protocol based on  
HTTP. The plugin automatically chooses between GET and POST requests  
based on the idempotency of the remote procedures using the  
introspective features of JSON-RPC 1.1.

The json\_rpc plgin allows a Rails application to choose to act as a  
service provider,  
as a client, or both. The plugin allows an application to set up an  
unlimited number of API services.

More information on

[http://rubyforge.org/projects/json-rpc/](http://rubyforge.org/projects/json-rpc/)

Documentation:

[http://json-rpc.rubyforge.org/](http://json-rpc.rubyforge.org/)

Installation:

script/plugin install svn://rubyforge.org/var/svn/json-rpc

# An example

## Server side

A Rails app may host any number of services. A service is declared in  
a controller,  
e.g.:

class ExampleServiceController \< ApplicationController

```
 json_rpc_service :name => 'DemoService', #

```

required  
:id =\> ‘urn:uuid:fdba4820-276b-11dc-ab85-0002a5d5c51b’, # required  
:version =\> ‘0.1’, # optional  
:summary =\> ‘A simple demonstration service.’, # optional  
:help =\> ‘[http://127.0.0.1:3000/services/index.html](http://127.0.0.1:3000/services/index.html)’, # optional  
:address =\> ‘[http://127.0.0.1:3000/services](http://127.0.0.1:3000/services)’ # optional

```
 json_rpc_procedure :name => 'sum', :proc => :+, #

```

required  
:summary =\> ‘Sums two numbers.’, # optional  
:help =\> ‘[http://127.0.0.1:3000/services/sum.html](http://127.0.0.1:3000/services/sum.html)’, # optional  
:idempotent =\> true, # optional  
:params =\> [{:name =\> ‘a’, :type =\> ‘num’}, # optional  
{:name =\> ‘b’, :type =\> ‘num’}], # optional  
:return =\> {:type =\> ‘num’} # optional

```
 json_rpc_procedure :name => 'time', :proc => lambda

```

{ Time.now.to\_s }

end

This defines a service called “DemoService”, a purely descriptive  
name, and two remotely callable procedures called “sum” and “time”.  
“sum” takes two numerical arguments and returns a number. “time”  
takes no arguments and may return anything. “sum” is declared to be  
idempotent; “time” is not.

Create a controller for each JSON-RPC service you need. Then declare  
routes for them in Rails’  
config/routes.rb file:

ActionController::Routing::Routes.draw do |map|  
map.connect ‘services/\*method’, :controller =\> ‘example\_service’,  
:action =\> ‘receive\_json\_rpc\_request’  
end

“services” is the external name of the service (it can be anything,  
of course).  
The complete URI to your service will be something like http://  
[www.yoursite.com/services](http://www.yoursite.com/services).

## Client Side

To connect to a service as defined above (locally or remotely),  
simply evaluate

s = JsonRpcClient.new ‘[http://www.yoursite.com/services](http://www.yoursite.com/services)’

You can now call procedures remotely using s as the receiving object:

s.time  
s.sum 24, 6  
s.sum :a =\> 24, :b =\> 6  
s.sum :b =\> 6, :a =\> 24  
s.sum :b =\> 6, ‘0’ =\> 24  
s.sum ‘0’ =\> 24, ‘1’ =\> 6

Note that all the above calls to +sum+ are equivalent. For further  
information, see the JSON-RPC 1.1  
specification draft. The use of named arguments is encouraged.

---

<div class="post-metadata">

**Author:** ![bodikp](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/e79b87/32.png) [@bodikp](https://www.ruby-forum.com/u/bodikp)\
**Post date:** [July 17, 2007, 9:21am UTC](https://www.ruby-forum.com/t/ann-json-rpc-1-1-plugin-for-rails/109604/2 "2007-07-17T09:21:11Z")

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On 7/4/07, Peter B. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote:

> introspective features of JSON-RPC 1.1.
> 
> The json\_rpc plgin allows a Rails application to choose to act as a  
> service provider,  
> as a client, or both. The plugin allows an application to set up an  
> unlimited number of API services.

Hi Peter,

Please excuse my ignorance, does this library allow for cross domain  
scripting or is it limited by XMLHttpRequest?

It certainly looks very useful and very clean sytnax. Congratulations.

Daniel