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httpc(3erl) | Erlang Module Definition | httpc(3erl) |
NAME¶
httpc - An HTTP/1.1 clientDESCRIPTION¶
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.
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 2616method() = 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.
EXPORTS¶
request(Url) ->
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, []}, [], []).
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:
Option ( 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.
- 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.
- headers_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, Function, 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.
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.
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()
NoProxyDesc = DomainDesc | HostName | IPDesc
DomainDesc = "*.Domain"
ex: "localhost" or
"foo.bar.se"
Port = integer()
ex: 8080
NoProxy = [NoProxyDesc]
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.
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.
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.
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.
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.
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.
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.
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.
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)inets 5.10.3 | Ericsson AB |