Class Net::HTTP::Persistent
In: lib/net/http/persistent.rb
Parent: Object

Persistent connections for Net::HTTP

Net::HTTP::Persistent maintains persistent connections across all the servers you wish to talk to. For each host:port you communicate with a single persistent connection is created.

Multiple Net::HTTP::Persistent objects will share the same set of connections.

For each thread you start a new connection will be created. A Net::HTTP::Persistent connection will not be shared across threads.

You can shut down the HTTP connections when done by calling shutdown. You should name your Net::HTTP::Persistent object if you intend to call this method.

Example:

  require 'net/http/persistent'

  uri = URI 'http://example.com/awesome/web/service'

  http = Net::HTTP::Persistent.new 'my_app_name'

  # perform a GET
  response = http.request uri

  # create a POST
  post_uri = uri + 'create'
  post = Net::HTTP::Post.new post_uri.path
  post.set_form_data 'some' => 'cool data'

  # perform the POST, the URI is always required
  response http.request post_uri, post

SSL

SSL connections are automatically created depending upon the scheme of the URI. SSL connections are automatically verified against the default certificate store for your computer. You can override this by changing verify_mode or by specifying an alternate cert_store.

Here are the SSL settings, see the individual methods for documentation:

certificate :This client‘s certificate
ca_file :The certificate-authority
cert_store :An SSL certificate store
private_key :The client‘s SSL private key
reuse_ssl_sessions :Reuse a previously opened SSL session for a new connection
ssl_version :Which specific SSL version to use
verify_callback :For server certificate verification
verify_mode :How connections should be verified

Proxies

A proxy can be set through proxy= or at initialization time by providing a second argument to ::new. The proxy may be the URI of the proxy server or :ENV which will consult environment variables.

See proxy= and proxy_from_env for details.

Headers

Headers may be specified for use in every request. headers are appended to any headers on the request. override_headers replace existing headers on the request.

The difference between the two can be seen in setting the User-Agent. Using http.headers[‘User-Agent’] = ‘MyUserAgent‘ will send "Ruby, MyUserAgent" while http.override_headers[‘User-Agent’] = ‘MyUserAgent‘ will send "MyUserAgent".

Tuning

Segregation

By providing an application name to ::new you can separate your connections from the connections of other applications.

Idle Timeout

If a connection hasn‘t been used for 5 seconds it will automatically be reset upon the next use to avoid attempting to send to a closed connection. This can be adjusted through idle_timeout.

Reducing this value may help avoid the "too many connection resets" error when sending non-idempotent requests while increasing this value will cause fewer round-trips.

Read Timeout

The amount of time allowed between reading two chunks from the socket. Set through read_timeout

Open Timeout

The amount of time to wait for a connection to be opened. Set through open_timeout.

Idle Timeout

If a connection has not been used in this many seconds it will be reset when a request would use the connection. The default idle timeout is unlimited. If you know the server‘s idle timeout setting this value will eliminate failures from attempting non-idempotent requests on closed connections. Set through idle_timeout.

Socket Options

Socket options may be set on newly-created connections. See socket_options for details.

Non-Idempotent Requests

By default non-idempotent requests will not be retried per RFC 2616. By setting retry_change_requests to true requests will automatically be retried once.

Only do this when you know that retrying a POST or other non-idempotent request is safe for your application and will not create duplicate resources.

The recommended way to handle non-idempotent requests is the following:

  require 'net/http/persistent'

  uri = URI 'http://example.com/awesome/web/service'
  post_uri = uri + 'create'

  http = Net::HTTP::Persistent.new 'my_app_name'

  post = Net::HTTP::Post.new post_uri.path
  # ... fill in POST request

  begin
    response = http.request post_uri, post
  rescue Net::HTTP::Persistent::Error

    # POST failed, make a new request to verify the server did not process
    # the request
    exists_uri = uri + '...'
    response = http.get exists_uri

    # Retry if it failed
    retry if response.code == '404'
  end

The method of determining if the resource was created or not is unique to the particular service you are using. Of course, you will want to add protection from infinite looping.

Methods

Classes and Modules

Class Net::HTTP::Persistent::Error
Class Net::HTTP::Persistent::SSLReuse

Constants

VERSION = '2.5.2'   The version of Net::HTTP::Persistent you are using

Attributes

ca_file  [R]  An SSL certificate authority. Setting this will set verify_mode to VERIFY_PEER.
cert_store  [R]  An SSL certificate store. Setting this will override the default certificate store. See verify_mode for more information.
certificate  [R]  This client‘s OpenSSL::X509::Certificate
debug_output  [RW]  Sends debug_output to this IO via Net::HTTP#set_debug_output.

Never use this method in production code, it causes a serious security hole.

headers  [R]  Headers that are added to every request using Net::HTTP#add_field
http_versions  [R]  Maps host:port to an HTTP version. This allows us to enable version specific features.
idle_timeout  [RW]  Maximum time an unused connection can remain idle before being automatically closed.
keep_alive  [RW]  The value sent in the Keep-Alive header. Defaults to 30. Not needed for HTTP/1.1 servers.

This may not work correctly for HTTP/1.0 servers

This method may be removed in a future version as RFC 2616 does not require this header.

name  [R]  A name for this connection. Allows you to keep your connections apart from everybody else‘s.
open_timeout  [RW]  Seconds to wait until a connection is opened. See Net::HTTP#open_timeout
override_headers  [R]  Headers that are added to every request using Net::HTTP#[]=
private_key  [R]  This client‘s SSL private key
proxy_uri  [R]  The URL through which requests will be proxied
read_timeout  [RW]  Seconds to wait until reading one block. See Net::HTTP#read_timeout
retry_change_requests  [RW]  Enable retries of non-idempotent requests that change data (e.g. POST requests) when the server has disconnected.

This will in the worst case lead to multiple requests with the same data, but it may be useful for some applications. Take care when enabling this option to ensure it is safe to POST or perform other non-idempotent requests to the server.

reuse_ssl_sessions  [RW]  By default SSL sessions are reused to avoid extra SSL handshakes. Set this to false if you have problems communicating with an HTTPS server like:
  SSL_connect [...] read finished A: unexpected message (OpenSSL::SSL::SSLError)
socket_options  [R]  An array of options for Socket#setsockopt.

By default the TCP_NODELAY option is set on sockets.

To set additional options append them to this array:

  http.socket_options << [Socket::SOL_SOCKET, Socket::SO_KEEPALIVE, 1]
ssl_version  [R]  SSL version to use.

By default, the version will be negotiated automatically between client and server. Ruby 1.9 and newer only.

verify_callback  [R]  SSL verification callback. Used when ca_file is set.
verify_mode  [R]  HTTPS verify mode. Defaults to OpenSSL::SSL::VERIFY_PEER which verifies the server certificate.

If no ca_file or cert_store is set the default system certificate store is used.

You can use verify_mode to override any default values.

Public Class methods

Creates a new Net::HTTP::Persistent.

Set name to keep your connections apart from everybody else‘s. Not required currently, but highly recommended. Your library name should be good enough. This parameter will be required in a future version.

proxy may be set to a URI::HTTP or :ENV to pick up proxy options from the environment. See proxy_from_env for details.

In order to use a URI for the proxy you may need to do some extra work beyond URI parsing if the proxy requires a password:

  proxy = URI 'http://proxy.example'
  proxy.user     = 'AzureDiamond'
  proxy.password = 'hunter2'

Public Instance methods

Sets the SSL certificate authority file.

Is the request idempotent or is retry_change_requests allowed

Overrides the default SSL certificate store used for verifying connections.

Sets this client‘s OpenSSL::X509::Certificate

Workaround for missing Net::HTTPRequest#connection_close? on Ruby 1.8

Workaround for missing Net::HTTPHeader#connection_close? on Ruby 1.8

Creates a new connection for uri

Workaround for missing Net::HTTPHeader#connection_keep_alive? on Ruby 1.8

Workaround for missing Net::HTTPRequest#connection_keep_alive? on Ruby 1.8

Returns an error message containing the number of requests performed on this connection

URI::escape wrapper

Returns the HTTP protocol version for uri

Is req idempotent according to RFC 2616?

If a connection hasn‘t been used since max_age it will be reset and reused

Adds "http://" to the String uri if it is missing.

Pipelines requests to the HTTP server at uri yielding responses if a block is given. Returns all responses recieved.

See Net::HTTP::Pipeline for further details.

Only if net-http-pipeline was required before net-http-persistent pipeline will be present.

Sets this client‘s SSL private key

Sets the proxy server. The proxy may be the URI of the proxy server, the symbol +:ENV+ which will read the proxy from the environment or nil to disable use of a proxy. See proxy_from_env for details on setting the proxy from the environment.

If the proxy URI is set after requests have been made, the next request will shut-down and re-open all connections.

If you are making some requests through a proxy and others without a proxy use separate Net::Http::Persistent instances.

Creates a URI for an HTTP proxy server from ENV variables.

If HTTP_PROXY is set a proxy will be returned.

If HTTP_PROXY_USER or HTTP_PROXY_PASS are set the URI is given the indicated user and password unless HTTP_PROXY contains either of these in the URI.

For Windows users, lowercase ENV variables are preferred over uppercase ENV variables.

Forces reconnection of HTTP connections.

Forces reconnection of SSL connections.

Makes a request on uri. If req is nil a Net::HTTP::Get is performed against uri.

If a block is passed request behaves like Net::HTTP#request (the body of the response will not have been read).

req must be a Net::HTTPRequest subclass (see Net::HTTP for a list).

If there is an error and the request is idempontent according to RFC 2616 it will be retried automatically.

Finishes then restarts the Net::HTTP connection

Shuts down all connections for thread.

Uses the current thread by default.

If you‘ve used Net::HTTP::Persistent across multiple threads you should call this in each thread when you‘re done making HTTP requests.

NOTE: Calling shutdown for another thread can be dangerous!

If the thread is still using the connection it may cause an error! It is best to call shutdown in the thread at the appropriate time instead!

Shuts down all connections in all threads

NOTE: THIS METHOD IS VERY DANGEROUS!

Do not call this method if other threads are still using their connections! Call shutdown at the appropriate time instead!

Use this method only as a last resort!

Enables SSL on connection

SSL version to use

SSL verification callback.

Sets the HTTPS verify mode. Defaults to OpenSSL::SSL::VERIFY_PEER.

Setting this to VERIFY_NONE is a VERY BAD IDEA and should NEVER be used. Securely transfer the correct certificate and update the default certificate store or set the ca file instead.

[Validate]