http
MODULE
http
MODULE SUMMARY
An HTTP/1.1 client
DESCRIPTION
This module provides the API to a HTTP/1.1 client according to
RFC 2616, caching is currently not supported.
Note
When starting the Inets application a manager process for the
default profile will be started. The functions in this API
that does not explicitly use a profile will acesses the
default profile. A profile keeps track of proxy options,
cookies and other options that can be applied to more than one
request.
If the scheme
https is used the ssl application needs to be started.
Also note that pipeling will only be used if the pipeline
timeout is set, otherwise persistent connections without
pipeling will be used e.i. the client always waits for
the previous response before sending the next request.
There are some usage examples in the Inets User's Guide.
COMMON DATA TYPES
Type definitions that are used more than once in
this module:
boolean() = true | false
string() = list of ASCII characters
request_id() = ref()
profile() = atom()
path() = string() representing a file path or directory path
HTTP CLIENT SERVICE START/STOP
A HTTP client can be configured to start when starting the inets
application or started dynamically in runtime by calling the
inets application API inets:start(httpc, ServiceConfig), or
inets:start(httpc, ServiceConfig, How)
see inets(3) Below follows a
description of the available configuration options.
-
{profile, profile()}
-
Name of the profile, see
common data types below, this option is mandantory.
-
{data_dir, path()}
-
Directory where the profile
may save persistent data, if omitted all cookies will be treated
as session cookies.
The client can be stopped using inets:stop(httpc, Pid) or
inets:stop(httpc, Profile).
HTTP DATA TYPES
Type definitions that are related to HTTP:
For more information about HTTP see rfc 2616
method() = head | get | put | post | trace | options | delete
request() - {url(), headers()} |
{url(), headers(), content_type(), body()}
url() = string() - Syntax according to the URI definition in rfc 2396, ex: "http://www.erlang.org"
status_line() =
{http_version(), status_code(), reason_phrase()}
http_version() = string() ex: "HTTP/1.1"
status_code() = integer()
reason_phrase() = string()
content_type() = string()
headers() = [{field(), value()}]
field() = string()
value() = string()
body() = string() | binary()
filename = string()
SSL DATA TYPES
Some type definitions relevant when using https,
for details ssl(3):
ssl_options() =
{verify, code()} | {depth, depth()} | {certfile, path()}
| {keyfile, path()} | {password, string()} | {cacertfile, path()}
| {ciphers, string()}
EXPORTS
cancel_request(RequestId) ->
cancel_request(RequestId, Profile) -> ok
Types:
RequestId = request_id() - A unique identifier as returned
by request/4
Profile = profile()
Cancels an asynchronous HTTP-request.
request(Url) ->
request(Url, Profile) -> {ok, Result} | {error, Reason}
Types:
Url = url()
Result = {status_line(), headers(),
body()} | {status_code(), body()} | request_id()
Profile = profile()
Reason = term()
Equivalent to http:request(get, {Url, []}, [], []).
request(Method, Request, HTTPOptions, Options) ->
request(Method, Request, HTTPOptions, Options, Profile) -> {ok, Result} | {ok, saved_to_file} | {error, Reason}
Types:
Method = method()
Request - request()
HTTPOptions - [HttpOption]
HTTPOption - {timeout, integer()} | {ssl, ssl_options()} | {autoredirect, boolean()} | {proxy_auth, {userstring(), passwordstring()}} | {version, http_version()} | {relaxed, boolean()}
autoredirect
This option is true by default i.e. the client will automatically retrive the information from the new URI and return that as the result instead of a 30X-result code. Note that for some 30X-result codes automatic redirect is not allowed in these cases the 30X-result will always be returned.
proxy_auth
A proxy-authorization header using the provided user name and password will be added to the request.
version
Can be used to make the client act as an HTTP/1.0 or
HTTP/0.9 client.
By default this is an HTTP/1.1 client. When
using HTTP/1.0 persistent connections will not be used.
relaxed
If set to true workarounds for known server deviations from
the HTTP-standard are enabled, defaults to false.
Options - [option()]
Option - {sync, boolean()} | {stream, StreamTo} | {body_format, body_format()} | {full_result, boolean()} | {headers_as_is, boolean()}
The request function will be synchronous and return a full http response by default.
StreamTo = self | {self, once} | filename()
Streams the body of a 200 or 206 response to the calling process
or to a file. When streaming to the calling process using
the option self the the following stream messages
will be sent to that process: {http, {RequestId,
stream_start, Headers}, {http, {RequestId, stream,
BinBodyPart}, {http, {RequestId, stream_end, Headers}. When
streaming to to the calling processes using the option
{self once} the first message will have an additional
element e.i. {http, {RequestId, stream_start, Headers, Pid},
this is the process id that should be used as an argument to
http:stream_next/1 to trigger the next message to be sent to
the calling process.
Note that it is possible that chunked encoding will add
headers so that there are more headers in the stream_end
message than in the stream_start.
When streaming to a file and the request is asynchronous the
message {http, {RequestId, saved_to_file}} will be sent.
body_format() = string() | binary()
The body_format option is only valid for the synchronous request and the default is string. When making an asynchronous request the body will always be received as a binary.
headers_as_is
The headers_as_is option is by default false, if set to true the headers provided by the user will be regarded as case sensitive. Note that the http standard requires them to be case insenstive. This feature should only be used if there is no other way to communicate with the server or for testing purpose. Also note that when this option is used no headers will be
automatically added, all necessary headers has to be provided by the user.
Result = {status_line(), headers(), body()} | {status_code(), body()} | request_id()
Profile = profile()
Reason = term()
Sends a HTTP-request. The function can be both synchronous
and asynchronous in the later case the function will return
{ok, RequestId} and later on message/messages will be sent to the
calling process on the format {http, {RequestId, Result}}
{http, {RequestId, {error, Reason}}},
{http, {RequestId, stream_start, Headers},
{http, {RequestId, stream, BinBodyPart},
{http, {RequestId, stream_end, Headers} or
{http, {RequestId, saved_to_file}}.
set_options(Options) ->
set_options(Options, Profile) -> ok | {error, Reason}
Types:
Options = [Option]
Option = {proxy, {Proxy, NoProxy}} | {max_sessions, MaxSessions}
| {max_keep_alive_length, MaxKeepAlive} | {keep_alive_timeout, KeepAliveTimeout} |
{max_pipeline_length, MaxPipeline} | {pipeline_timeout, PipelineTimeout} | {cookies | CookieMode} | {ipv6, Ipv6Mode} | {verbose, VerboseMode}
Proxy = {Hostname, Port}
Hostname = string()
ex: "localhost" or "foo.bar.se"
Port = integer()
ex: 8080
NoProxy = [NoProxyDesc]
NoProxyDesc = DomainDesc | HostName | IPDesc
DomainDesc = "*.Domain"
ex: "*.ericsson.se"
IpDesc = string()
ex: "134.138" or "[FEDC:BA98" (all IP-adresses starting with 134.138 or FEDC:BA98), "66.35.250.150" or "[2010:836B:4179::836B:4179]" (a complete IP-address).
MaxSessions = integer()
Maximum number of persistent connections to a host.Default is 2.
MaxKeepAlive = integer()
Maximum number of outstanding requests on the same connection to a host. Default is 2.
KeepAliveTimeout = integer()
If a persistent connection is idle longer than the keep_alive_timeout the client will close the connection. Default is 2 min. The server may also have a such a time out but you should not count on it!
MaxPipeline = integer()
Maximum number of outstanding requests on a piplined connection to a host. Default is 2.
PipelineTimeout = integer()
If a persistent connection is idle longer than the pipeline_timeout the client will close the connection. Default is 0 which will result in
that pipeling will not be used.
CookieMode = enabled | disabled | verify
Default is disabled. If Cookies are enabled all valid cookies will automatically be saved in the client manager's cookie database. If the option verify is used the function http:verify_cookie/2 has to be called for the cookie to be saved.
ipv6Mode = enabled | disabled
By default enabled. This should normally be what you want. When it is enabled you can use both ipv4 and ipv6. The option is here to provide a workaround for buggy ipv6 stacks to ensure that ipv4 will always work.
VerboseMode = false | verbose |debug | trace
By default false. This option unless it is set to false switches on different levels of erlang trace on the client. It is a debug feature.
Profile = profile()
Sets options to be used for subsequent
requests.
Note
If possible the client will keep its connections
alive and use persistent connections
with or without pipeline depending on configuration
and current circumstances. The HTTP/1.1 specification does not
provide a guideline for how many requests that would be
ideal to be sent on a persistent connection,
this very much depends on the
application. Note that a very long queue of requests may cause a
user perceived delays as earlier request may take a long time
to complete. The HTTP/1.1 specification does suggest a
limit of 2 persistent connections per server, which is the
default value of the max_sessions option.
stream_next(Pid) -> ok
Types:
Pid = pid() - as received in the stream_start message
Triggers the next message to be streamed, e.i.
same behavior as active once for sockets.
verify_cookie(SetCookieHeaders, Url) ->
verify_cookie(SetCookieHeaders, Url, Profile) -> ok | {error, Reason}
Types:
SetCookieHeaders = headers() - where field = "set-cookie"
Url = url()
Profile = profile()
Saves the cookies defined in SetCookieHeaders
in the client profile's cookie database. You need to
call this function if you set the option cookies to verify.
If no profile is specifed the default profile will be used.
cookie_header(Url) ->
cookie_header(Url, Profile) -> header() | {error, Rason}
Types:
Url = url()
Profile = profile()
Returns the cookie header that would be sent
when making a request to Url using the profile Profile.
If no profile is specifed the default profile will be used.
SEE ALSO
inets 5.0.13
Copyright © 1991-2009
Ericsson AB