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NAME
httpc - An HTTP/1.1 client
DESCRIPTION
This module provides the API to a HTTP/1.1 compatible 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 do not explicitly use a profile will access 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. When https links
needs to go through a proxy the CONNECT method extension to HTTP-1.1 is used to establish
a tunnel and then the connection is upgraded to TLS, however "TLS upgrade" according to
RFC 2817 is not supported.
Also note that pipelining will only be used if the pipeline timeout is set, otherwise
persistent connections without pipelining 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
ip_address() = See inet(3erl)
socket_opt() = See the Options used by gen_tcp(3erl) and
ssl(3erl) connect(s)
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() = [header()]
header() = {field(), value()}
field() = string()
value() = string()
body() = string() |
binary() |
{fun(accumulator()) -> body_processing_result(),
accumulator()} |
{chunkify,
fun(accumulator()) -> body_processing_result(),
accumulator()}
body_processing_result() = eof | {ok, iolist(), accumulator()}
accumulator() = term()
filename() = string()
SSL DATA TYPES
See ssl(3erl) for information about ssl options (ssloptions()).
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(3erl). Below follows a
description of the available configuration options.
{profile, profile()}:
Name of the profile, see common data types below, this option is mandatory.
{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).
EXPORTS
request(Url) ->
request(Url, Profile) -> {ok, Result} | {error, Reason}
Types:
Url = url()
Result = {status_line(), headers(), Body} | {status_code(), Body} | request_id()
Body = string() | binary()
Profile = profile() | pid() (when started stand_alone)
Reason = term()
Equivalent to httpc: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 = http_options()
http_options() = [http_option()]
http_option() = {timeout, timeout()} | {connect_timeout, timeout()} | {ssl,
ssloptions()} | {essl, ssloptions()} | {autoredirect, boolean()} | {proxy_auth,
{userstring(), passwordstring()}} | {version, http_version()} | {relaxed,
boolean()} | {url_encode, boolean()}
timeout() = integer() >= 0 | infinity
Options = options()
options() = [option()]
option() = {sync, boolean()} | {stream, stream_to()} | {body_format,
body_format()} | {full_result, boolean()} | {headers_as_is, boolean() |
{socket_opts, socket_opts()} | {receiver, receiver()}, {ipv6_host_with_brackets,
boolean()}}
stream_to() = none | self | {self, once} | filename()
socket_opts() = [socket_opt()]
receiver() = pid() | function()/1 | {Module, Function, Args}
Module = atom()
Function = atom()
Args = list()
body_format() = string | binary
Result = {status_line(), headers(), Body} | {status_code(), Body} | request_id()
Body = string() | binary()
Profile = profile() | pid() (when started stand_alone)
Reason = {connect_failed, term()} | {send_failed, term()} | 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 the information
will be delivered to the receiver depending on that value.
Http option (http_option()) details:
timeout:
Timeout time for the request.
The clock starts ticking as soon as the request has been sent.
Time is in milliseconds.
Defaults to infinity.
connect_timeout:
Connection timeout time, used during the initial request, when the client is
connecting to the server.
Time is in milliseconds.
Defaults to the value of the timeout option.
ssl:
This is the default ssl config option, currently defaults to essl, see below.
Defaults to [].
essl:
If using the Erlang based implementation of SSL, these SSL-specific options are
used.
Defaults to [].
autoredirect:
Should the client automatically retrieve 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.
Defaults to true.
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.
Defaults to the string "HTTP/1.1".
relaxed:
If set to true workarounds for known server deviations from the HTTP-standard
are enabled.
Defaults to false.
url_encode:
Will apply Percent-encoding, also known as URL encoding on the URL.
Defaults to false.
Option (option()) details:
sync:
Shall the request be synchronous or asynchronous.
Defaults to true.
stream:
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 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.
Defaults to none.
body_format:
Defines if the body shall be delivered as a string or as a binary. This option
is only valid for the synchronous request.
Defaults to string.
full_result:
Should a "full result" be returned to the caller (that is, the body, the
headers and the entire status-line) or not (the body and the status code).
Defaults to true.
header_as_is:
Shall the headers provided by the user be made lower case or 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 have to be provided by the user.
Defaults to false.
socket_opts:
Socket options to be used for this and subsequent request(s).
Overrides any value set by the set_options function.
Note that the validity of the options are not checked in any way.
Note that this may change the socket behaviour (see inet:setopts/2) for an
already existing one, and therefore an already connected request handler.
By default the socket options set by the set_options/1,2 function are used when
establishing a connection.
receiver:
Defines how the client will deliver the result of an asynchroneous request
(sync has the value false).
pid():
Message(s) will be sent to this process in the format:
{http, ReplyInfo}
function/1:
Information will be delivered to the receiver via calls to the provided fun:
Receiver(ReplyInfo)
{Module, Funcion, Args}:
Information will be delivered to the receiver via calls to the callback
function:
apply(Module, Function, [ReplyInfo | Args])
In all of the above cases, ReplyInfo has the following structure:
{RequestId, saved_to_file}
{RequestId, {error, Reason}}
{RequestId, Result}
{RequestId, stream_start, Headers}
{RequestId, stream_start, Headers, HandlerPid}
{RequestId, stream, BinBodyPart}
{RequestId, stream_end, Headers}
Defaults to the pid() of the process calling the request function (self()).
ipv6_host_with_brackets:
When parsing the Host-Port part of an URI with a IPv6 address with brackets,
shall we retain those brackets (true) or strip them (false).
Defaults to false.
cancel_request(RequestId) ->
cancel_request(RequestId, Profile) -> ok
Types:
RequestId = request_id() - A unique identifier as returned by request/4
Profile = profile() | pid() (when started stand_alone)
Cancels an asynchronous HTTP-request. Note this does not guarantee that the request
response will not be delivered, as it is asynchronous the the request may already
have been completed when the cancellation arrives.
set_options(Options) ->
set_options(Options, Profile) -> ok | {error, Reason}
Types:
Options = [Option]
Option = {proxy, {Proxy, NoProxy}} | {https_proxy, {Proxy, NoProxy}} |
{max_sessions, MaxSessions} | {max_keep_alive_length, MaxKeepAlive} |
{keep_alive_timeout, KeepAliveTimeout} | {max_pipeline_length, MaxPipeline} |
{pipeline_timeout, PipelineTimeout} | {cookies, CookieMode} | {ipfamily,
IpFamily} | {ip, IpAddress} | {port, Port} | {socket_opts, socket_opts()} |
{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-addresses starting with 134.138 or
FEDC:BA98), "66.35.250.150" or "[2010:836B:4179::836B:4179]" (a complete IP-
address).
proxy defaults to {undefined, []} e.i. no proxy is configured and https_proxy
defaults to the value of proxy.
MaxSessions = integer()
Default is 2. Maximum number of persistent connections to a host.
MaxKeepAlive = integer()
Default is 5. Maximum number of outstanding requests on the same connection to
a host.
KeepAliveTimeout = integer()
Default is 120000 (= 2 min). If a persistent connection is idle longer than
the keep_alive_timeout in milliseconds, the client will close the connection.
The server may also have such a time out but you should not count on it!
MaxPipeline = integer()
Default is 2. Maximum number of outstanding requests on a pipelined connection
to a host.
PipelineTimeout = integer()
Default is 0, which will result in pipelining not being used. If a persistent
connection is idle longer than the pipeline_timeout in milliseconds, the
client will close the connection.
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 store_cookies/2 has to be called for the cookies
to be saved.
IpFamily = inet | inet6 | inet6fb4
By default inet. When it is set to inet6fb4 you can use both ipv4 and ipv6. It
first tries inet6 and if that does not works falls back to inet. The option is
here to provide a workaround for buggy ipv6 stacks to ensure that ipv4 will
always work.
IpAddress = ip_address()
If the host has several network interfaces, this option specifies which one to
use. See gen_tcp:connect/3,4 for more info.
Port = integer()
Specify which local port number to use. See gen_tcp:connect/3,4 for more info.
socket_opts() = [socket_opt()]
The options are appended to the socket options used by the client.
These are the default values when a new request handler is started (for the
initial connect). They are passed directly to the underlying transport
(gen_tcp or ssl) without verification!
VerboseMode = false | verbose | debug | trace
Default is false. This option is used to switch on (or off) different levels
of erlang trace on the client. It is a debug feature.
Profile = profile() | pid() (when started stand_alone)
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 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 delay as earlier requests 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.
get_options(OptionItems) -> {ok, Values} | {error, Reason}
get_options(OptionItems, Profile) -> {ok, Values} | {error, Reason}
Types:
OptionItems = all | [option_item()]
option_item() = proxy | https_proxy max_sessions | keep_alive_timeout |
max_keep_alive_length | pipeline_timeout | max_pipeline_length | cookies |
ipfamily | ip | port | socket_opts | verbose
Profile = profile() | pid() (when started stand_alone)
Values = [{option_item(), term()}]
Reason = term()
Retrieves the options currently used by the client.
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.
store_cookies(SetCookieHeaders, Url) ->
store_cookies(SetCookieHeaders, Url, Profile) -> ok | {error, Reason}
Types:
SetCookieHeaders = headers() - where field = "set-cookie"
Url = url()
Profile = profile() | pid() (when started stand_alone)
Saves the cookies defined in SetCookieHeaders in the client profile's cookie
database. You need to call this function if you have set the option cookies to
verify. If no profile is specified the default profile will be used.
cookie_header(Url) ->
cookie_header(Url, Profile | Opts) -> header() | {error, Reason}
cookie_header(Url, Opts, Profile) -> header() | {error, Reason}
Types:
Url = url()
Opts = [cookie_header_opt()]
Profile = profile() | pid() (when started stand_alone)
cookie_header_opt() = {ipv6_host_with_brackets, boolean()}
Returns the cookie header that would be sent when making a request to Url using the
profile Profile. If no profile is specified the default profile will be used.
The option ipv6_host_with_bracket deals with how to parse IPv6 addresses. See the
Options argument of the request/4,5 for more info.
reset_cookies() -> void()
reset_cookies(Profile) -> void()
Types:
Profile = profile() | pid() (when started stand_alone)
Resets (clears) the cookie database for the specified Profile. If no profile is
specified the default profile will be used.
which_cookies() -> cookies()
which_cookies(Profile) -> cookies()
Types:
Profile = profile() | pid() (when started stand_alone)
cookies() = [cookie_stores()]
cookie_stores() = {cookies, cookies()} | {session_cookies, cookies()}
cookies() = [cookie()]
cookie() = term()
This function produces a list of the entire cookie database. It is intended for
debugging/testing purposes. If no profile is specified the default profile will be
used.
which_sessions() -> session_info()
which_sessions(Profile) -> session_info()
Types:
Profile = profile() | pid() (when started stand_alone)
session_info() = {GoodSessions, BadSessions, NonSessions}
GoodSessions = session()
BadSessions = tuple()
NonSessions = term()
This function produces a slightly processed dump of the session database. It is
intended for debugging. If no profile is specified the default profile will be
used.
info() -> list()
info(Profile) -> list()
Types:
Profile = profile() | pid() (when started stand_alone)
This function produces a list of miscelleneous info. It is intended for debugging.
If no profile is specified the default profile will be used.
SEE ALSO
RFC 2616, inets(3erl), gen_tcp(3erl), ssl(3erl)