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<h1>3 HTTP Client</h1>
<h3><a name="id60140">3.1
Introduction</a></h3>
<p>The HTTP client default profile will be started when the inets
application is started and is then available to all processes on
that erlang node. Other profiles may also be started at
application startup, or profiles can be started and stopped
dynamically in runtime. Each client profile will spawn a new
process to handle each request unless there is a possibility to use
a persistent connection with or without pipelining.
The client will add a <span class="code">host</span> header and an empty
<span class="code">te</span> header if there are no such headers present in the request.</p>
<p>The client supports ipv6 as long as the underlying mechanisms also do
so.</p>
<h3><a name="id61256">3.2
Configuration</a></h3>
<p> What to put in the erlang node application configuration file
in order to start a profile at application startup.</p>
<div class="example"><pre>
[{inets, [{services, [{httpc, PropertyList}]}]}]
</pre></div>
<p>For valid properties see
<span class="bold_code"><a href="httpc.html">httpc(3)</a></span>. </p>
<h3><a name="id60633">3.3
Using the HTTP Client API</a></h3>
<div class="example"><pre>
1 > inets:start().
ok
</pre></div>
<p> The following calls uses the default client profile.
Use the proxy "www-proxy.mycompany.com:8000",
but not for requests to localhost. This will apply to all subsequent
requests</p>
<div class="example"><pre>
2 > httpc:set_options([{proxy, {{"www-proxy.mycompany.com", 8000},
["localhost"]}}]).
ok
</pre></div>
<p>An ordinary synchronous request. </p>
<div class="example"><pre>
3 > {ok, {{Version, 200, ReasonPhrase}, Headers, Body}} =
httpc:request(get, {"http://www.erlang.org", []}, [], []).
</pre></div>
<p>With all default values, as above, a get request can also be written
like this.</p>
<div class="example"><pre>
4 > {ok, {{Version, 200, ReasonPhrase}, Headers, Body}} =
httpc:request("http://www.erlang.org").
</pre></div>
<p>An ordinary asynchronous request. The result will be sent
to the calling process in the form <span class="code">{http, {ReqestId, Result}}</span></p>
<div class="example"><pre>
5 > {ok, RequestId} =
httpc:request(get, {"http://www.erlang.org", []}, [], [{sync, false}]).
</pre></div>
<p>In this case the calling process is the shell, so we receive the
result.</p>
<div class="example"><pre>
6 > receive {http, {RequestId, Result}} -> ok after 500 -> error end.
ok
</pre></div>
<p>Send a request with a specified connection header. </p>
<div class="example"><pre>
7 > {ok, {{NewVersion, 200, NewReasonPhrase}, NewHeaders, NewBody}} =
httpc:request(get, {"http://www.erlang.org", [{"connection", "close"}]},
[], []).
</pre></div>
<p>Start a HTTP client profile. </p>
<div class="example"><pre>
8 > {ok, Pid} = inets:start(httpc, [{profile, foo}]).
{ok, <0.45.0>}
</pre></div>
<p>The new profile has no proxy settings so the connection will
be refused</p>
<div class="example"><pre>
9 > httpc:request("http://www.erlang.org", foo).
{error, econnrefused}
</pre></div>
<p>Stop a HTTP client profile. </p>
<div class="example"><pre>
10 > inets:stop(httpc, foo).
ok
</pre></div>
<p>Alternatively:</p>
<div class="example"><pre>
10 > inets:stop(httpc, Pid).
ok
</pre></div>
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