httpc
An HTTP/1.1 client
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(3) socket_opt() = See the Options used by gen_tcp(3) and ssl(3) 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(3) 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(3). Below follows a
description of the available configuration options.
The client can be stopped using inets:stop(httpc, Pid)
or
inets:stop(httpc, Profile)
.
Functions
request(Url) ->
request(Url, Profile) -> {ok, Result} | {error, Reason}
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}
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
RequestId = request_id() - A unique identifier as returned by request/4
Profile = profile() | pid() (when started
stand_alone
)
Cancels an asynchronous HTTP-request.
set_options(Options) ->
set_options(Options, Profile) -> ok | {error, Reason}
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()
Port = integer()
NoProxy = [NoProxyDesc]
NoProxyDesc = DomainDesc | HostName | IPDesc
DomainDesc = "*.Domain"
IpDesc = string()
MaxSessions = integer()
MaxKeepAlive = integer()
KeepAliveTimeout = integer()
MaxPipeline = integer()
PipelineTimeout = integer()
CookieMode = enabled | disabled | verify
IpFamily = inet | inet6 | inet6fb4
IpAddress = ip_address()
Port = integer()
socket_opts() = [socket_opt()]
VerboseMode = false | verbose | debug | trace
Profile = profile() | pid() (when started
stand_alone
)
2
.
Maximum number of persistent connections to a host.5
.
Maximum number of outstanding requests on the same connection to
a host.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!2
.
Maximum number of outstanding requests on a pipelined connection
to a host.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. 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.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.false
.
This option is used to switch on (or off)
different levels of erlang trace on the client.
It is a debug feature.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}
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
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}
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}
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()
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()
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()
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()
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(3), gen_tcp(3), ssl(3)