google-api-ruby-client/lib/google/api_client.rb

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# Copyright 2010 Google Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
require 'httpadapter'
require 'json'
require 'google/api_client/discovery'
module Google
# TODO(bobaman): Document all this stuff.
##
# This class manages communication with a single API.
class APIClient
##
# An error which is raised when there is an unexpected response or other
# transport error that prevents an operation from succeeding.
class TransmissionError < StandardError
end
def initialize(options={})
@options = {
# TODO: What configuration options need to go here?
}.merge(options)
# Force immediate type-checking and short-cut resolution
self.parser
self.authorization
self.http_adapter
return self
end
##
# Returns the parser used by the client.
def parser
unless @options[:parser]
require 'google/api_client/parsers/json_parser'
# NOTE: Do not rely on this default value, as it may change
@options[:parser] = JSONParser
end
return @options[:parser]
end
##
# Returns the authorization mechanism used by the client.
#
# @return [#generate_authenticated_request] The authorization mechanism.
def authorization
case @options[:authorization]
when :oauth_1, :oauth
require 'signet/oauth_1/client'
# NOTE: Do not rely on this default value, as it may change
@options[:authorization] = Signet::OAuth1::Client.new(
:temporary_credential_uri =>
'https://www.google.com/accounts/OAuthGetRequestToken',
:authorization_uri =>
'https://www.google.com/accounts/OAuthAuthorizeToken',
:token_credential_uri =>
'https://www.google.com/accounts/OAuthGetAccessToken',
:client_credential_key => 'anonymous',
:client_credential_secret => 'anonymous'
)
when nil
# No authorization mechanism
else
if !@options[:authorization].respond_to?(
:generate_authenticated_request)
raise TypeError,
'Expected authorization mechanism to respond to ' +
'#generate_authenticated_request.'
end
end
return @options[:authorization]
end
##
# Sets the authorization mechanism used by the client.
#
# @param [#generate_authenticated_request] new_authorization
# The new authorization mechanism.
def authorization=(new_authorization)
@options[:authorization] = new_authorization
return self.authorization
end
##
# Returns the HTTP adapter used by the client.
def http_adapter
return @options[:http_adapter] ||= (begin
require 'httpadapter/adapters/net_http'
@options[:http_adapter] = HTTPAdapter::NetHTTPRequestAdapter
end)
end
##
# Returns the URI for the discovery document.
#
# @return [Addressable::URI] The URI of the discovery document.
def discovery_uri
return @options[:discovery_uri] ||= (begin
if @options[:service]
service_id = @options[:service]
service_version = @options[:service_version] || 'v1'
Addressable::URI.parse(
"http://www.googleapis.com/discovery/0.1/describe" +
"?api=#{service_id}"
)
else
raise ArgumentError,
'Missing required configuration value, :discovery_uri.'
end
end)
end
##
# Returns the parsed discovery document.
#
# @return [Hash] The parsed JSON from the discovery document.
def discovery_document
return @discovery_document ||= (begin
request = ['GET', self.discovery_uri.to_s, [], []]
response = self.transmit_request(request)
status, headers, body = response
if status == 200 # TODO(bobaman) Better status code handling?
merged_body = StringIO.new
body.each do |chunk|
merged_body.write(chunk)
end
merged_body.rewind
JSON.parse(merged_body.string)
else
raise TransmissionError,
"Could not retrieve discovery document at: #{self.discovery_uri}"
end
end)
end
##
# Returns a list of services this client instance has performed discovery
# for. This may return multiple versions of the same service.
#
# @return [Array]
# A list of discovered <code>Google::APIClient::Service</code> objects.
def discovered_services
return @discovered_services ||= (begin
service_names = self.discovery_document['data'].keys()
services = []
for service_name in service_names
versions = self.discovery_document['data'][service_name]
for service_version in versions.keys()
service_description =
self.discovery_document['data'][service_name][service_version]
services << ::Google::APIClient::Service.new(
service_name,
service_version,
service_description
)
end
end
services
end)
end
##
# Returns the service object for a given service name and service version.
#
# @param [String, Symbol] service_name The service name.
# @param [String] service_version The desired version of the service.
#
# @return [Google::APIClient::Service] The service object.
def discovered_service(service_name, service_version='v1')
if !service_name.kind_of?(String) && !service_name.kind_of?(Symbol)
raise TypeError,
"Expected String or Symbol, got #{service_name.class}."
end
service_name = service_name.to_s
for service in self.discovered_services
if service.name == service_name &&
service.version.to_s == service_version.to_s
return service
end
end
return nil
end
##
# Returns the method object for a given RPC name and service version.
#
# @param [String, Symbol] rpc_name The RPC name of the desired method.
# @param [String] service_version The desired version of the service.
#
# @return [Google::APIClient::Method] The method object.
def discovered_method(rpc_name, service_version='v1')
if !rpc_name.kind_of?(String) && !rpc_name.kind_of?(Symbol)
raise TypeError,
"Expected String or Symbol, got #{rpc_name.class}."
end
rpc_name = rpc_name.to_s
for service in self.discovered_services
# This looks kinda weird, but is not a real problem because there's
# almost always only one service, and this is memoized anyhow.
if service.version.to_s == service_version.to_s
return service.to_h[rpc_name] if service.to_h[rpc_name]
end
end
return nil
end
##
# Returns the service object with the highest version number.
#
# <em>Warning</em>: This method should be used with great care. As APIs
# are updated, minor differences between versions may cause
# incompatibilities. Requesting a specific version will avoid this issue.
#
# @param [String, Symbol] service_name The name of the service.
#
# @return [Google::APIClient::Service] The service object.
def latest_service_version(service_name)
if !service_name.kind_of?(String) && !service_name.kind_of?(Symbol)
raise TypeError,
"Expected String or Symbol, got #{service_name.class}."
end
service_name = service_name.to_s
return (self.discovered_services.select do |service|
service.name == service_name
end).sort.last
end
##
# Generates a request.
#
# @param [Google::APIClient::Method, String] api_method
# The method object or the RPC name of the method being executed.
# @param [Hash, Array] parameters
# The parameters to send to the method.
# @param [String] body The body of the request.
# @param [Hash, Array] headers The HTTP headers for the request.
# @param [Hash] options
# The configuration parameters for the request.
# - <code>:service_version</code> —
# The service version. Only used if <code>api_method</code> is a
# <code>String</code>. Defaults to <code>'v1'</code>.
# - <code>:parser</code> —
# The parser for the response.
# - <code>:authorization</code> —
# The authorization mechanism for the response. Used only if
# <code>:signed</code> is <code>true</code>.
# - <code>:signed</code> —
# <code>true</code> if the request must be signed, <code>false</code>
# otherwise. Defaults to <code>true</code> if an authorization
# mechanism has been set, <code>false</code> otherwise.
#
# @return [Array] The generated request.
#
# @example
# request = client.generate_request(
# 'chili.activities.list',
# {'scope' => '@self', 'userId' => '@me', 'alt' => 'json'}
# )
# method, uri, headers, body = request
def generate_request(
api_method, parameters={}, body='', headers=[], options={})
options={
:parser => self.parser,
:service_version => 'v1',
:authorization => self.authorization
}.merge(options)
# The default value for the :signed option depends on whether an
# authorization mechanism has been set.
if options[:authorization]
options = {:signed => true}.merge(options)
else
options = {:signed => false}.merge(options)
end
if api_method.kind_of?(String) || api_method.kind_of?(Symbol)
api_method = self.discovered_method(
api_method.to_s, options[:service_version]
)
elsif !api_method.kind_of?(::Google::APIClient::Method)
raise TypeError,
"Expected String, Symbol, or Google::APIClient::Method, " +
"got #{api_method.class}."
end
unless api_method
raise ArgumentError, "API method could not be found."
end
request = api_method.generate_request(parameters, body, headers)
if options[:signed]
request = self.sign_request(request, options[:authorization])
end
return request
end
##
# Generates a request and transmits it.
#
# @param [Google::APIClient::Method, String] api_method
# The method object or the RPC name of the method being executed.
# @param [Hash, Array] parameters
# The parameters to send to the method.
# @param [String] body The body of the request.
# @param [Hash, Array] headers The HTTP headers for the request.
# @param [Hash] options
# The configuration parameters for the request.
# - <code>:service_version</code> —
# The service version. Only used if <code>api_method</code> is a
# <code>String</code>. Defaults to <code>'v1'</code>.
# - <code>:adapter</code> —
# The HTTP adapter.
# - <code>:parser</code> —
# The parser for the response.
# - <code>:authorization</code> —
# The authorization mechanism for the response. Used only if
# <code>:signed</code> is <code>true</code>.
# - <code>:signed</code> —
# <code>true</code> if the request must be signed, <code>false</code>
# otherwise. Defaults to <code>true</code>.
#
# @return [Array] The response from the API.
#
# @example
# response = client.execute(
# 'chili.activities.list',
# {'scope' => '@self', 'userId' => '@me', 'alt' => 'json'}
# )
# status, headers, body = response
def execute(api_method, parameters={}, body='', headers=[], options={})
request = self.generate_request(
api_method, parameters, body, headers, options
)
return self.transmit_request(
request,
options[:adapter] || self.http_adapter
)
end
##
# Transmits the request using the current HTTP adapter.
#
# @param [Array] request The request to transmit.
# @param [#transmit] adapter The HTTP adapter.
#
# @return [Array] The response from the server.
def transmit_request(request, adapter=self.http_adapter)
::HTTPAdapter.transmit(request, adapter)
end
##
# Signs a request using the current authorization mechanism.
#
# @param [Array] request The request to sign.
# @param [#generate_authenticated_request] authorization
# The authorization mechanism.
#
# @return [Array] The signed request.
def sign_request(request, authorization=self.authorization)
return authorization.generate_authenticated_request(
:request => request
)
end
end
end
require 'google/api_client/version'