NAME
Net::Async::HTTP - use HTTP with IO::Async
SYNOPSIS
use Future::AsyncAwait;
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 = await $http->do_request(
uri => URI->new( "http://www.cpan.org/" ),
);
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.
headers => ARRAY or HASH
Since version 0.45.
A set of extra headers to apply to every outgoing request. May be
specified either as an even-sized array containing key/value pairs, or
a hash.
Individual header values may be added or changed without replacing the
entire set by using the configure method and passing a key called
+headers:
$http->configure( +headers => { One_More => "Key" } );
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. Give 0 to disable the limit entirely. See also the
"Connection Pooling" section documented above.
Currently, if not supplied it will default to 1. However, it has been
found in practice that most programs will raise this limit to something
higher, perhaps 3 or 4. Therefore, a future version of this module may
set a higher value.
To test if your application will handle this correctly, you can set a
different default by setting an environment variable:
$ NET_ASYNC_HTTP_MAXCONNS=3 perl ...
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.
close_after_request => BOOL
Since version 0.45.
Optional. If true, will set the Connection: close header on outgoing
requests and disable pipelining, thus making every request use a new
connection.
family => INT
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 socket family and 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 types 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.
require_SSL => BOOL
Optional. If true, then any attempt to make a request that does not use
SSL (either by calling request, or as a result of a redirection) will
immediately fail.
SOCKS_*
Since version 0.42.
Additionally, any parameters whose names start with SOCKS_ will be
stored and used by Net::Async::SOCKS to establish connections via a
configured proxy.
METHODS
The following methods documented in an await expression 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 )
do_request
$response = await $http->do_request( %args );
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::Requests:
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.
family => INT
Optional. Restricts the socket family for connecting. If not defined,
will default to the globally-configured value in the object.
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 name. 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 it will be used directly, and a
content_type field must also be supplied to describe it.
If this is an ARRAY ref and the request method is POST, it will be
form encoded. It should contain an even-sized list of field names and
values. For more detail see "POST" in HTTP::Request::Common.
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.
headers => ARRAY|HASH
Optional. If provided, contains additional HTTP headers to set on the
constructed request object. If provided as an ARRAY reference, it
should contain an even-sized list of name/value pairs.
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_ready => CODE
Optional. A callback that is invoked once a socket connection is
established with the HTTP server, but before the request is actually
sent over it. This may be used by the client code to inspect the
socket, or perform any other operations on it. This code is expected
to return a Future; only once that has completed will the request
cycle continue. If it fails, that failure is propagated to the
caller.
$f = $on_ready->( $connection )
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
do_request (void)
$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 )
GET, HEAD, PUT, ...
$response = await $http->GET( $uri, %args );
$response = await $http->HEAD( $uri, %args );
$response = await $http->PUT( $uri, $content, %args );
$response = await $http->POST( $uri, $content, %args );
$response = await $http->PATCH( $uri, $content, %args );
Convenient wrappers for performing GET, HEAD, PUT, POST or PATCH
requests 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.
prepare_request
$http->prepare_request( $request )
Called just before the HTTP::Request object is sent to the server.
process_response
$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
register_decoder
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
use Future::AsyncAwait;
use Future::Utils qw( fmap_void );
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,
concurrent => 5;
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>