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 <leonerd@leonerd.org.uk>