# http

### MODULE

http

### MODULE SUMMARY

A HTTP/1.1 client

### DESCRIPTION

This module provides the API to a HTTP/1.1 client according to RFC 2616, however this early version is somewhat limited for instance caching is not supported.

| The functions request/4, and set_options/1, will start the inets application if it was not already started. When starting the inets application the client manager process that spawns request handlers, keeps track of proxy options etc will be started. Normaly the application using this API should have started inets application. This is also true for the ssl application when using https.

Note that there are some usage examples in the Inets User's Guide.

### COMMON DATA TYPES

Here follows type definitions that are used more than once in this module.

    boolean() = true | false

    string() = list of ASCII characters

    request_id() = ref()

### HTTP DATA TYPES

Here follows type definitions that are related to the HTTP protocol. For more information about the HTTP protocol 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()}]

     filed() = string()

     value() = string()

     body() = string() | binary()

### SSL DATA TYPES

Here follows 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) -> ok`

Types:

`RequestId = request_id() - A unique identifier as returned by request/4`

Cancels an asynchronous HTTP-request.

`request(Method, Request, HTTPOptions, Options) -> {ok, Result} | {error, Reason}`

Types:

`Method = method()`
`Request - request()`
`HTTPOptions - [HttpOption]`
`HTTPOption - {timeout, integer()} | {ssl, ssl_options()} | {autoredirect, boolean()}`

autoredirect - is true by default e.i. the client will automaticly 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.
`Options - [option()]`
`Option - {sync, boolean()} | {body_format, body_format()} | {full_result, boolean()}`
The request function will be synchronous and return a full http response by default.
`body_format() = string() | binary()`
The body_format options is only valid for the syncronus request and the defult is string, when making an asynchronous request the body will always be received as a binary.
`Result = {status_line(), headers(), body()} | {status_code(), body()} | request_id()`

Sends a HTTP-request. The function can be both syncronus and asynchronous in the later case the function will return {ok, RequestId} and later on a message will be sent to the calling process on the format {http, {RequestId, Result}} or {http, {RequestId, {error, Reason}}}.

`set_options(Options) -> ok`

Types:

`Options = [Option]`
`Option = {proxy, {Proxy, NoProxy}} | {max_sessions, MaxSessions} | {max_pipeline_length, MaxPipeline} | {pipeline_timeout, PipelineTimeout} | {cookies | CookieMode}`
`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 compleat IP-address).
`MaxSessions = integer()`
Maximum number of persistent connections to a host.Default is 2.
`MaxPipeline = integer()`
Maximum number of outstanding requests on the same connection to a host. Default is 2.
`PipelineTimeout = integer()`
If a persistant connection is idle longer than the pipeline_timeout the client will close the connection. Default is infinity. The server may also have a such a time out but you should not count on it!
`CookieMode = enabled | disabled | verify`
Default is disabled. If Cookies are enabled all valid cookies will automaticly be saved in the client managers cookie database. If the option verify is used the function http:verify_cookie/2 has to be called for the cookie to be saved.

Sets options to be used for subsequent requests. Later implementations may support user profiles, but currently these are global settings for all clients running on the same erlang node.

If possible the client will keep its connections alive and ues them to pipeline requests whenever the circumstances allow. The HTTP/1.1 specification does not provide a guideline for how many requests that would be ideal to pipeline, this very much depends on the application. Note that a very long pipeline may cause a user precived delays as earlier request may take a long time to compleate. The HTTP/1.1 specification does suggest a limit of 2 persistent connections per server, which is the defalt value of the max_seesions option.

`verify_cookie(SetCookieHeaders, Url) -> ok`

Types:

`SetCookieHeaders = headers() - where field = "set-cookie"`
`Url = url()`

Saves the cookies defined in SetCookieHeaders in the client managers cookie database. You need to call this function if you set the option cookies to verify.

### SEE ALSO

RFC 2616, ssl(3)

### AUTHORS

Ingela Anderton Andin - support@erlang.ericsson.se

inets 4.2
Copyright © 1991-2005 Ericsson AB