Wrest 1.4.3

© Copyright 2009-2011 Sidu Ponnappa. All Rights Reserved.

Wrest is a ruby REST/HTTP client library which

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Examples

For Facebook, Twitter, Delicious, GitHub and other API examples, see github.com/kaiwren/wrest/tree/master/examples

Basic Http Calls

GET

POST

DELETE

To delete a resource:

'https://api.del.icio.us/v1/posts/delete'.to_uri(
                                             :username => 'kaiwren',
                                             :password => 'fupupp1es'
                                           ).delete(
                                             :url => 'http://c2.com'
                                           )

Caching

Wrest supports caching with pluggable back-ends.

Wrest::Caching.default_to_hash!     # Hash should NEVER be used in a production environment. It is unbounded and will keep increasing in size.
c42 = "http://c42.in".to_uri.get

A Memcached based caching back-end is available in Wrest. You can get instructions on how to install Memcached on your system here. The Dalli gem is used by Wrest to interface with Memcached. Install dalli using 'gem install dalli'.

Use the following method to enable caching for all requests, and set Memcached as the default back-end.

Wrest::Caching.default_to_memcached!

For fine-grained control over the cache store (or to use multiple cache stores in the same codebase), you can use this API:

r1 = "http://c42.in".to_uri.using_memcached.get
r2 = "http://c42.in".to_uri.using_hash.get

A detailed writeup regarding caching as defined by RFC 2616, and how Wrest implements caching is at Wrest Caching Doc

You can create your own back-ends for Wrest caching by implementing the interface implemented in github.com/kaiwren/wrest/blob/master/lib/wrest/components/cache_store/memcached.rb

To explicitly disable caching for specific requests:

"http://c42.in".to_uri.disable_cache.get

Callbacks

Uri level callbacks

You can define a set of callbacks that are invoked based on the http codes of the responses to any requests on a given uri.

"http://google.com".to_uri(:callback => {
            200      => lambda {|response| Wrest.logger.info "Ok." },
            400..499 => lambda {|response| Wrest.logger.error "Invalid. #{response.body}"},
            300..302 => lambda {|response| Wrest.logger.debug "Redirected. #{response.message}" }
          }).get

Per request callbacks

You can also define callbacks that are invoked based on the http code of the response to a particular request.

"http://google.com".to_uri.get do |callback|
  callback.on_ok do |response|
    Wrest.logger.info "Ok."
  end

  callback.on(202) do |response|
    Wrest.logger.info "Accepted."
  end

  callback.on(200..206) do |response|
    Wrest.logger.info "Successful."
  end
end

Please note that Wrest is a synchronous library. All requests are blocking, and will not return till the request is completed and appropriate callbacks executed.

Asynchronous requests

Asynchronous requests are non-blocking. They do not return a response and the request is executed on a separate thread. The only way to access the response while using asynchronous request is through callbacks.

Asynchronous requests support pluggable backends. The default backend used for asynchronous requests is ruby threads.

"http://c42.in".to_uri.get_async do |callback|
  callback.on_ok do |response|
    Wrest.logger.info "Ok."
  end
end

sleep 1 # Causes thread created by get_async to execute

You can change the default to eventmachine.

Wrest::AsyncRequest.default_to_em!

You can also override the default on Uri objects.

"http://c42.in".to_uri.using_em.get_async do |callback|
  callback.on_ok do |response|
    Wrest.logger.info "Ok."
  end
end

Note: The current implementation of asynchronous requests is currently in alpha and should not be used in production.

Other useful stuff

Allows any class to hold an attributes hash, somewhat like ActiveResource. It also supports several extensions to this base fuctionality such as support for typecasting attribute values. See examples/twitter.rb and examples/wow_realm_status.rb for more samples.

Example:

class Demon
  include Wrest::Components::Container

  always_has       :id
  typecast         :age          =>  as_integer,
                   :chi          =>  lambda{|chi| Chi.new(chi)}

  alias_accessors  :chi => :energy                  
end

kai_wren = Demon.new('id' => '1', 'age' => '1500', 'chi' => '1024', 'teacher' => 'Viss')
kai_wren.id       # => '1'
kai_wren.age      # => 1500
kai_wren.chi      # => #<Chi:0x113af8c @count="1024">
kai_wren.energy   # => #<Chi:0x113af8c @count="1024">
kai_wren.teacher  # => 'Viss'

Logging

The Wrest logger can be set and accessed through Wrest.logger and is configured by default to log to STDOUT. If you're using Wrest in a Rails application, you can configure logging by adding a config/initializers/wrest.rb file with the following contents :

Wrest.logger = Rails.logger

Build

Standard options are available and can be listed using rake -T. Use rake:rcov for coverage and rake:rdoc to generate documentation. The link to the continuous integration build is over at the C42 Engineering open source page.

Documentation

Wrest RDocs can be found at wrest.rubyforge.org

Roadmap

Features that are planned, in progress or already implemented are documented in the CHANGELOG starting from version 0.0.8.

Installation

The source is available at git://github.com/kaiwren/wrest.git

To install the Wrest gem, do (sudo) gem install wrest.

Wrest is currently available as a gem for for Ruby and JRuby.

Shell

You can launch the interactive Wrest shell by running bin/wrest if you have the source or invoking wrest from your prompt if you've installed the gem.

$ wrest
>> y 'http://twitter.com/statuses/public_timeline.json'.to_uri(:timeout => 5).get.deserialise

Testing

Start the Sinatra test server for functional test.

rake -f spec/sample_app/Rakefile  # runs on port 3000

Start a memcached daemon/process on port 11211

/usr/local/bin/memcached

Run the tests in a different terminal:

# Run the normal test suite.
rake

# Runs the functional test suite.
rake rspec:functional

Contributors