Action Web Service – Serving APIs on rails
Action Web Service provides a way to publish interoperable web service APIs with Rails without spending a lot of time delving into protocol details.
Features
-
SOAP RPC protocol support
-
Dynamic WSDL generation for APIs
-
XML-RPC protocol support
-
Clients that use the same API definitions as the server for easy interoperability with other Action Web Service based applications
-
Type signature hints to improve interoperability with static languages
-
Active Record model class support in signatures
Defining your APIs
You specify the methods you want to make available as API methods in an ActionWebService::API::Base derivative, and then specify this API definition class wherever you want to use that API.
The implementation of the methods is done seperately to the API specification.
Method name inflection
Action Web Service will camelcase the method names according to Rails Inflector rules for the API visible to public callers. What this means, for example is that the method names in generated WSDL will be camelcased, and callers will have to supply the camelcased name in their requests for the request to succeed.
If you do not desire this behaviour, you can turn it off with the ActionWebService::API::Base inflect_names
option.
Inflection examples
:add => Add
:find_all => FindAll
Disabling inflection
class PersonAPI < ActionWebService::API::Base
inflect_names false
end
API definition example
class PersonAPI < ActionWebService::API::Base
api_method :add, :expects => [:string, :string, :bool], :returns => [:int]
api_method :remove, :expects => [:int], :returns => [:bool]
end
API usage example
class PersonController < ActionController::Base
web_service_api PersonAPI
def add
end
def remove
end
end
Publishing your APIs
Action Web Service uses Action Pack to process protocol requests. There are two modes of dispatching protocol requests, Direct, and Delegated.
Direct dispatching
This is the default mode. In this mode, controller actions implement the API methods, and parameters for incoming method calls will be placed in @params
(keyed by name), and @method_params
(ordered list).
The return value of the action is sent back as the return value to the caller.
In this mode, a special api
action is generated in the target controller to unwrap the protocol request, forward it on to the relevant action and send back the wrapped return value. This action must not be overridden.
Direct dispatching example
class PersonController < ApplicationController
web_service_api PersonAPI
def add
end
def remove
end
end
class PersonAPI < ActionWebService::API::Base
...
end
For this example, protocol requests for Add
and Remove
methods sent to /person/api
will be routed to the actions add
and remove
.
Delegated dispatching
This mode can be turned on by setting the web_service_dispatching_mode
option in a controller.
In this mode, the controller contains one or more web service objects (objects that implement an ActionWebService::API::Base definition). These web service objects are each mapped onto one controller action only.
Delegated dispatching example
class ApiController < ApplicationController
web_service_dispatching_mode :delegated
web_service :person, PersonService.new
end
class PersonService < ActionWebService::Base
web_service_api PersonAPI
def add
end
def remove
end
end
class PersonAPI < ActionWebService::API::Base
...
end
For this example, all protocol requests for PersonService
are sent to the /api/person
action.
The /api/person
action is generated when the web_service
method is called. This action must not be overridden.
Other controller actions (actions that aren’t the target of a web_service
call) are ignored for ActionWebService purposes, and can do normal action tasks.
Using the client support
Action Web Service includes client classes that can use the same API definition as the server. The advantage of this approach is that your client will have the same support for Active Record and structured types as the server, and can just use them directly, and rely on the marshaling to Do The Right Thing.
Note: The client support is intended for communication between Ruby on Rails applications that both use Action Web Service. It may work with other servers, but that is not its intended use, and interoperability can’t be guaranteed, especially not for .NET web services.
Web services protocol specifications are complex, and Action Web Service client support can only be guaranteed to work with a subset.
Factory created client example
class BlogManagerController < ApplicationController
web_client_api :blogger, :xmlrpc, 'http://url/to/blog/api/RPC2', :handler_name => 'blogger'
end
class SearchingController < ApplicationController
web_client_api :google, :soap, 'http://url/to/blog/api/beta', :service_name => 'GoogleSearch'
end
See ActionWebService::API::ActionController::ClassMethods for more details.
Manually created client example
class PersonAPI < ActionWebService::API::Base
api_method :find_all, :returns => [[Person]]
end
soap_client = ActionWebService::Client::Soap.new(PersonAPI, "http://...")
persons = soap_client.find_all
class BloggerAPI < ActionWebService::API::Base
inflect_names false
api_method :getRecentPosts, :returns => [[Blog::Post]]
end
blog = ActionWebService::Client::XmlRpc.new(BloggerAPI, "http://.../xmlrpc", :handler_name => "blogger")
posts = blog.getRecentPosts
See ActionWebService::Client::Soap and ActionWebService::Client::XmlRpc for more details.
Dependencies
Action Web Service requires that the Action Pack and Active Record are either available to be required immediately or are accessible as GEMs.
It also requires a version of Ruby that includes SOAP support in the standard library. At least version 1.8.2 final (2004-12-25) of Ruby is recommended, this is the version tested against.
Download
The latest Action Web Service version can be downloaded from rubyforge.org/projects/actionservice
Installation
You can install Action Web Service with the following command.
% [sudo] ruby setup.rb
License
Action Web Service is released under the MIT license.
Support
The Ruby on Rails mailing list
Or, to contact the author, send mail to [email protected]