NAME `Net::Async::HTTP' - use HTTP with `IO::Async' SYNOPSIS use IO::Async::Loop; use Net::Async::HTTP; use URI; my $loop = IO::Async::Loop->new(); my $http = Net::Async::HTTP->new(); $loop->add( $http ); my ( $response ) = $http->do_request( uri => URI->new( "http://www.cpan.org/" ), )->get; print "Front page of http://www.cpan.org/ is:\n"; print $response->as_string; DESCRIPTION This object class implements an asynchronous HTTP user agent. It sends requests to servers, returning Future instances to yield responses when they are received. The object supports multiple concurrent connections to servers, and allows multiple requests in the pipeline to any one connection. Normally, only one such object will be needed per program to support any number of requests. As well as using futures the module also supports a callback-based interface. This module optionally supports SSL connections, if IO::Async::SSL is installed. If so, SSL can be requested either by passing a URI with the `https' scheme, or by passing a true value as the `SSL' parameter. Connection Pooling There are three ways in which connections to HTTP server hosts are managed by this object, controlled by the value of `max_connections_per_host'. This controls when new connections are established to servers, as compared to waiting for existing connections to be free, as new requests are made to them. They are: max_connections_per_host = 1 This is the default setting. In this mode, there will be one connection per host on which there are active or pending requests. If new requests are made while an existing one is outstanding, they will be queued to wait for it. If pipelining is active on the connection (because both the `pipeline' option is true and the connection is known to be an HTTP/1.1 server), then requests will be pipelined into the connection awaiting their response. If not, they will be queued awaiting a response to the previous before sending the next. max_connections_per_host > 1 In this mode, there can be more than one connection per host. If a new request is made, it will try to re-use idle connections if there are any, or if they are all busy it will create a new connection to the host, up to the configured limit. max_connections_per_host = 0 In this mode, there is no upper limit to the number of connections per host. Every new request will try to reuse an idle connection, or else create a new one if all the existing ones are busy. These modes all apply per hostname / server port pair; they do not affect the behaviour of connections made to differing hostnames, or differing ports on the same hostname. PARAMETERS The following named parameters may be passed to `new' or `configure': user_agent => STRING A string to set in the `User-Agent' HTTP header. If not supplied, one will be constructed that declares `Net::Async::HTTP' and the version number. max_redirects => INT Optional. How many levels of redirection to follow. If not supplied, will default to 3. Give 0 to disable redirection entirely. max_in_flight => INT Optional. The maximum number of in-flight requests to allow per host when pipelining is enabled and supported on that host. If more requests are made over this limit they will be queued internally by the object and not sent to the server until responses are received. If not supplied, will default to 4. Give 0 to disable the limit entirely. max_connections_per_host => INT Optional. Controls the maximum number of connections per hostname/server port pair, before requests will be queued awaiting one to be free. If not supplied, will default to 1. Give 0 to disable the limit entirely. See also the Connection Pooling section documented above. timeout => NUM Optional. How long in seconds to wait before giving up on a request. If not supplied then no default will be applied, and no timeout will take place. stall_timeout => NUM Optional. How long in seconds to wait after each write or read of data on a socket, before giving up on a request. This may be more useful than `timeout' on large-file operations, as it will not time out provided that regular progress is still being made. proxy_host => STRING proxy_port => INT Optional. Default values to apply to each `request' method. cookie_jar => HTTP::Cookies Optional. A reference to a HTTP::Cookies object. Will be used to set cookies in requests and store them from responses. pipeline => BOOL Optional. If false, disables HTTP/1.1-style request pipelining. local_host => STRING local_port => INT local_addrs => ARRAY local_addr => HASH or ARRAY Optional. Parameters to pass on to the `connect' method used to connect sockets to HTTP servers. Sets the local socket address to `bind()' to. For more detail, see the documentation in IO::Async::Connector. fail_on_error => BOOL Optional. Affects the behaviour of response handling when a `4xx' or `5xx' response code is received. When false, these responses will be processed as other responses and yielded as the result of the future, or passed to the `on_response' callback. When true, such an error response causes the future to fail, or the `on_error' callback to be invoked. The HTTP response and request objects will be passed as well as the code and message, and the failure name will be `http'. ( $code_message, "http", $response, $request ) = $f->failure $on_error->( "$code $message", $response, $request ) read_len => INT write_len => INT Optional. Used to set the reading and writing buffer lengths on the underlying `IO::Async::Stream' objects that represent connections to the server. If not define, a default of 64 KiB will be used. ip_tos => INT or STRING Optional. Used to set the `IP_TOS' socket option on client sockets. If given, should either be a `IPTOS_*' constant, or one of the string names `lowdelay', `throughput', `reliability' or `mincost'. If undefined or left absent, no option will be set. decode_content => BOOL Optional. If true, incoming responses that have a recognised `Content-Encoding' are handled by the module, and decompressed content is passed to the body handling callback or returned in the `HTTP::Response'. See CONTENT DECODING below for details of which encoding methods are recognised. When this option is enabled, outgoing requests also have the `Accept-Encoding' header added to them if it does not already exist. Currently the default is false, because this behaviour is new, but it may default to true in a later version. Applications which care which behaviour applies should set this to a defined value to ensure it doesn't change. SSL_* Additionally, any parameters whose names start with `SSL_' will be stored and passed on requests to perform SSL requests. This simplifies configuration of common SSL parameters. METHODS The following methods documented with a trailing call to `->get' return Future instances. When returning a Future, the following methods all indicate HTTP-level errors using the Future failure name of `http'. If the error relates to a specific response it will be included. The original request is also included. $f->fail( $message, "http", $response, $request ) $response = $http->do_request( %args )->get Send an HTTP request to a server, returning a Future that will yield the response. The request may be represented by an HTTP::Request object, or a URI object, depending on the arguments passed. The following named arguments are used for `HTTP::Request's: request => HTTP::Request A reference to an `HTTP::Request' object host => STRING Hostname of the server to connect to port => INT or STRING Optional. Port number or service of the server to connect to. If not defined, will default to `http' or `https' depending on whether SSL is being used. SSL => BOOL Optional. If true, an SSL connection will be used. The following named arguments are used for `URI' requests: uri => URI or STRING A reference to a `URI' object, or a plain string giving the request URI. If the scheme is `https' then an SSL connection will be used. method => STRING Optional. The HTTP method. If missing, `GET' is used. content => STRING or ARRAY ref Optional. The body content to use for `PUT' or `POST' requests. If this is a plain scalar instead of an ARRAY ref, it will not be form encoded. In this case, a `content_type' field must also be supplied to describe it. content_type => STRING The type of non-form data `content'. user => STRING pass => STRING Optional. If both are given, the HTTP Basic Authorization header will be sent with these details. proxy_host => STRING proxy_port => INT Optional. Override the hostname or port number implied by the URI. For either request type, it takes the following arguments: request_body => STRING | CODE | Future Optional. Allows request body content to be generated by a future or callback, rather than being provided as part of the `request' object. This can either be a plain string, a `CODE' reference to a generator function, or a future. As this is passed to the underlying IO::Async::Stream `write' method, the usual semantics apply here. If passed a `CODE' reference, it will be called repeatedly whenever it's safe to write. The code should should return `undef' to indicate completion. If passed a `Future' it is expected to eventually yield the body value. As with the `content' parameter, the `content_type' field should be specified explicitly in the request header, as should the content length (typically via the HTTP::Request `content_length' method). See also examples/PUT.pl. expect_continue => BOOL Optional. If true, sets the `Expect' request header to the value `100-continue' and does not send the `request_body' parameter until a `100 Continue' response is received from the server. If an error response is received then the `request_body' code, if present, will not be invoked. on_redirect => CODE Optional. A callback that is invoked if a redirect response is received, before the new location is fetched. It will be passed the response and the new URL. $on_redirect->( $response, $location ) on_body_write => CODE Optional. A callback that is invoked after each successful `syswrite' of the body content. This may be used to implement an upload progress indicator or similar. It will be passed the total number of bytes of body content written so far (i.e. excluding bytes consumed in the header). $on_body_write->( $written ) max_redirects => INT Optional. How many levels of redirection to follow. If not supplied, will default to the value given in the constructor. timeout => NUM stall_timeout => NUM Optional. Overrides the object's configured timeout values for this one request. If not specified, will use the configured defaults. On a timeout, the returned future will fail with either `timeout' or `stall_timeout' as the operation name. ( $message, "timeout" ) = $f->failure $http->do_request( %args ) When not returning a future, the following extra arguments are used as callbacks instead: on_response => CODE A callback that is invoked when a response to this request has been received. It will be passed an HTTP::Response object containing the response the server sent. $on_response->( $response ) on_header => CODE Alternative to `on_response'. A callback that is invoked when the header of a response has been received. It is expected to return a `CODE' reference for handling chunks of body content. This `CODE' reference will be invoked with no arguments once the end of the request has been reached, and whatever it returns will be used as the result of the returned `Future', if there is one. $on_body_chunk = $on_header->( $header ) $on_body_chunk->( $data ) $response = $on_body_chunk->() on_error => CODE A callback that is invoked if an error occurs while trying to send the request or obtain the response. It will be passed an error message. $on_error->( $message ) If this is invoked because of a received `4xx' or `5xx' error code in an HTTP response, it will be invoked with the response and request objects as well. $on_error->( $message, $response, $request ) $response = $http->GET( $uri, %args )->get $response = $http->HEAD( $uri, %args )->get $response = $http->PUT( $uri, $content, %args )->get $response = $http->POST( $uri, $content, %args )->get Convenient wrappers for using the `GET', `HEAD', `PUT' or `POST' methods with a `URI' object and few if any other arguments, returning a `Future'. Remember that `POST' with non-form data (as indicated by a plain scalar instead of an `ARRAY' reference of form data name/value pairs) needs a `content_type' key in `%args'. SUBCLASS METHODS The following methods are intended as points for subclasses to override, to add extra functionallity. $http->prepare_request( $request ) Called just before the `HTTP::Request' object is sent to the server. $http->process_response( $response ) Called after a non-redirect `HTTP::Response' has been received from a server. The originating request will be set in the object. CONTENT DECODING If the required decompression modules are installed and available, compressed content can be decoded. If the received `Content-Encoding' is recognised and the required module is available, the content is transparently decoded and the decoded content is returned in the resulting response object, or passed to the data chunk handler. In this case, the original `Content-Encoding' header will be deleted from the response, and its value will be available instead as `X-Original-Content-Encoding'. The following content encoding types are recognised by these modules: * gzip (q=0.7) and deflate (q=0.5) Recognised if Compress::Raw::Zlib version 2.057 or newer is installed. * bzip2 (q=0.8) Recognised if Compress::Bzip2 version 2.10 or newer is installed. Other content encoding types can be registered by calling the following method Net::Async::HTTP->register_decoder( $name, $q, $make_decoder ) Registers an encoding type called `$name', at the quality value `$q'. In order to decode this encoding type, `$make_decoder' will be invoked with no paramters, and expected to return a CODE reference to perform one instance of decoding. $decoder = $make_decoder->() This decoder will be invoked on string buffers to decode them until the end of stream is reached, when it will be invoked with no arguments. $content = $decoder->( $encoded_content ) $content = $decoder->() # EOS EXAMPLES Concurrent GET The `Future'-returning `GET' method makes it easy to await multiple URLs at once, by using the Future::Utils `fmap_void' utility my @URLs = ( ... ); my $http = Net::Async::HTTP->new( ... ); $loop->add( $http ); my $future = fmap_void { my ( $url ) = @_; $http->GET( $url ) ->on_done( sub { my $response = shift; say "$url succeeded: ", $response->code; say " Content-Type":", $response->content_type; } ) ->on_fail( sub { my $failure = shift; say "$url failed: $failure"; } ); } foreach => \@URLs; $loop->await( $future ); SEE ALSO * http://tools.ietf.org/html/rfc2616 - Hypertext Transfer Protocol -- HTTP/1.1 SPONSORS Parts of this code, or bugfixes to it were paid for by * SocialFlow http://www.socialflow.com * Shadowcat Systems http://www.shadow.cat * NET-A-PORTER http://www.net-a-porter.com * Cisco http://www.cisco.com AUTHOR Paul Evans