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<h1 class="lined-header"><span>gun(3)</span></h1>
<h2 id="_name">Name</h2>
<p>gun - Asynchronous HTTP client</p>
<h2 id="_description">Description</h2>
<p>The <code>gun</code> module provides an asynchronous interface for connecting and communicating with Web servers over HTTP, HTTP/2 or Websocket.</p>
<h2 id="_exports">Exports</h2>
<p>Connection:</p>
<ul><li><a href="../gun.open">gun:open(3)</a> - Open a connection to the given host and port
</li>
<li><a href="../gun.open_unix">gun:open_unix(3)</a> - Open a connection to the given Unix domain socket
</li>
</ul>
<!-- @todo * link:../gun.shutdown[gun:shutdown(3)] - Gracefully close the connection-->
<ul><li><a href="../gun.close">gun:close(3)</a> - Brutally close the connection
</li>
<li><a href="../gun.info">gun:info(3)</a> - Obtain information about the connection
</li>
</ul>
<p>Requests:</p>
<ul><li><a href="../gun.get">gun:get(3)</a> - Get a resource representation
</li>
<li><a href="../gun.head">gun:head(3)</a> - Get headers of a resource representation
</li>
<li><a href="../gun.options">gun:options(3)</a> - Query the capabilities of the server or a resource
</li>
<li><a href="../gun.patch">gun:patch(3)</a> - Apply a set of changes to a resource
</li>
<li><a href="../gun.post">gun:post(3)</a> - Process the enclosed representation according to a resource's own semantics
</li>
<li><a href="../gun.put">gun:put(3)</a> - Create or replace a resource
</li>
<li><a href="../gun.delete">gun:delete(3)</a> - Delete a resource
</li>
<li><a href="../gun.request">gun:request(3)</a> - Perform the given request
</li>
<li><a href="../gun.data">gun:data(3)</a> - Stream the body of a request
</li>
</ul>
<p>Messages:</p>
<ul><li><a href="../gun.await">gun:await(3)</a> - Wait for a response
</li>
<li><a href="../gun.await_body">gun:await_body(3)</a> - Wait for the complete response body
</li>
<li><a href="../gun.await_up">gun:await_up(3)</a> - Wait for the connection to be up
</li>
<li><a href="../gun.flush">gun:flush(3)</a> - Flush all messages related to a connection or a stream
</li>
</ul>
<p>Streams:</p>
<ul><li><a href="../gun.cancel">gun:cancel(3)</a> - Cancel the given stream
</li>
</ul>
<p>Websocket:</p>
<ul><li><a href="../gun.ws_upgrade">gun:ws_upgrade(3)</a> - Upgrade to Websocket
</li>
<li><a href="../gun.ws_send">gun:ws_send(3)</a> - Send Websocket frames
</li>
</ul>
<h2 id="_messages">Messages</h2>
<p>Gun will inform the calling process of events asynchronously by sending any of the following messages:</p>
<p>Connection:</p>
<ul><li><a href="../gun_up">gun_up(3)</a> - The connection is up
</li>
<li><a href="../gun_down">gun_down(3)</a> - The connection is down
</li>
<li><a href="../gun_upgrade">gun_upgrade(3)</a> - Successful protocol upgrade
</li>
<li><a href="../gun_error">gun_error(3)</a> - Stream or connection-wide error
</li>
</ul>
<p>Responses:</p>
<ul><li><a href="../gun_push">gun_push(3)</a> - Server-initiated push
</li>
<li><a href="../gun_inform">gun_inform(3)</a> - Informational response
</li>
<li><a href="../gun_response">gun_response(3)</a> - Response
</li>
<li><a href="../gun_data">gun_data(3)</a> - Response body
</li>
<li><a href="../gun_trailers">gun_trailers(3)</a> - Response trailers
</li>
</ul>
<p>Websocket:</p>
<ul><li><a href="../gun_ws">gun_ws(3)</a> - Websocket frame
</li>
</ul>
<p>The response messages will be sent to the process that opened the connection by default. The <code>reply_to</code> request option can be used to redirect request-specific messages to a different process.</p>
<h2 id="_types">Types</h2>
<h3 id="_http_opts">http_opts()</h3>
<div class="listingblock"><div class="content"><!-- Generator: GNU source-highlight 3.1.9
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><tt><b><font color="#000000">http_opts</font></b>() <font color="#990000">::</font> #{
<font color="#0000FF">keepalive</font> <font color="#990000">=></font> <b><font color="#000000">timeout</font></b>(),
<font color="#0000FF">transform_header_name</font> <font color="#990000">=></font> <b><font color="#0000FF">fun</font></b>((<b><font color="#000080">binary</font></b>()) <font color="#990000">-></font> <b><font color="#000080">binary</font></b>()),
<font color="#0000FF">version</font> <font color="#990000">=></font> <font color="#FF6600">'HTTP/1.1'</font> | <font color="#FF6600">'HTTP/1.0'</font>
}</tt></pre>
</div></div>
<p>Configuration for the HTTP protocol.</p>
<p>The default value is given next to the option name:</p>
<!-- @todo Document content_handlers and gun_sse_h.-->
<dl><dt>keepalive (5000)</dt>
<dd><p>Time between pings in milliseconds. Since the HTTP protocol has no standardized way to ping the server, Gun will simply send an empty line when the connection is idle. Gun only makes a best effort here as servers usually have configurable limits to drop idle connections. Use <code>infinity</code> to disable.</p>
</dd>
<dt>transform_header_name - see below</dt>
<dd><p>A function that will be applied to all header names before they are sent to the server. Gun assumes that all header names are in lower case. This function is useful if you, for example, need to re-case header names in the event that the server incorrectly considers the case of header names to be significant.</p>
</dd>
<dt>version (<code>'HTTP/1.1'</code>)</dt>
<dd><p>HTTP version to use.</p>
</dd>
</dl>
<h3 id="_http2_opts">http2_opts()</h3>
<div class="listingblock"><div class="content"><!-- Generator: GNU source-highlight 3.1.9
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><tt><b><font color="#000000">http2_opts</font></b>() <font color="#990000">::</font> #{
<font color="#0000FF">keepalive</font> <font color="#990000">=></font> <b><font color="#000000">timeout</font></b>()
}</tt></pre>
</div></div>
<p>Configuration for the HTTP/2 protocol.</p>
<p>The default value is given next to the option name:</p>
<!-- @todo Document content_handlers and gun_sse_h.-->
<dl><dt>keepalive (5000)</dt>
<dd><p>Time between pings in milliseconds.</p>
</dd>
</dl>
<!-- @todo Allow and document max_frame_size_sent.-->
<h3 id="_opts">opts()</h3>
<div class="listingblock"><div class="content"><!-- Generator: GNU source-highlight 3.1.9
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><tt><b><font color="#000000">opts</font></b>() <font color="#990000">::</font> #{
<font color="#0000FF">connect_timeout</font> <font color="#990000">=></font> <b><font color="#000000">timeout</font></b>(),
<font color="#0000FF">http_opts</font> <font color="#990000">=></font> <b><font color="#000000">http_opts</font></b>(),
<font color="#0000FF">http2_opts</font> <font color="#990000">=></font> <b><font color="#000000">http2_opts</font></b>(),
<font color="#0000FF">protocols</font> <font color="#990000">=></font> [<font color="#FF6600">http</font> | <font color="#FF6600">http2</font>],
<font color="#0000FF">retry</font> <font color="#990000">=></font> <b><font color="#000000">non_neg_integer</font></b>(),
<font color="#0000FF">retry_timeout</font> <font color="#990000">=></font> <b><font color="#000000">pos_integer</font></b>(),
<font color="#0000FF">trace</font> <font color="#990000">=></font> <b><font color="#000000">boolean</font></b>(),
<font color="#0000FF">transport</font> <font color="#990000">=></font> <font color="#FF6600">tcp</font> | <font color="#FF6600">tls</font>,
<font color="#0000FF">transport_opts</font> <font color="#990000">=></font> [<b><font color="#000000">gen_tcp:connect_option</font></b>()] | [<b><font color="#000000">ssl:connect_option</font></b>()],
<font color="#0000FF">ws_opts</font> <font color="#990000">=></font> <b><font color="#000000">ws_opts</font></b>()
}</tt></pre>
</div></div>
<p>Configuration for the connection.</p>
<p>The default value is given next to the option name:</p>
<dl><dt>connect_timeout (infinity)</dt>
<dd><p>Connection timeout.</p>
</dd>
<dt>http_opts (#{})</dt>
<dd><p>Options specific to the HTTP protocol.</p>
</dd>
<dt>http2_opts (#{})</dt>
<dd><p>Options specific to the HTTP/2 protocol.</p>
</dd>
<dt>protocols - see below</dt>
<dd><p>Ordered list of preferred protocols. When the transport is <code>tcp</code>, this list must contain exactly one protocol. When the transport is <code>tls</code>, this list must contain at least one protocol and will be used to negotiate a protocol via ALPN. When the server does not support ALPN then <code>http</code> will always be used. Defaults to <code>[http]</code> when the transport is <code>tcp</code>, and <code>[http2, http]</code> when the transport is <code>tls</code>.</p>
</dd>
<dt>retry (5)</dt>
<dd><p>Number of times Gun will try to reconnect on failure before giving up.</p>
</dd>
<dt>retry_timeout (5000)</dt>
<dd><p>Time between retries in milliseconds.</p>
</dd>
<dt>trace (false)</dt>
<dd><p>Whether to enable <code>dbg</code> tracing of the connection process. Should only be used during debugging.</p>
</dd>
<dt>transport - see below</dt>
<dd><p>Whether to use TLS or plain TCP. The default varies depending on the port used. Port 443 defaults to <code>tls</code>. All other ports default to <code>tcp</code>.</p>
</dd>
<dt>transport_opts ([])</dt>
<dd><p>Transport options. They are TCP options or TLS options depending on the selected transport.</p>
</dd>
<dt>ws_opts (#{})</dt>
<dd><p>Options specific to the Websocket protocol.</p>
</dd>
</dl>
<h3 id="_req_opts">req_opts()</h3>
<div class="listingblock"><div class="content"><!-- Generator: GNU source-highlight 3.1.9
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><tt><b><font color="#000000">req_opts</font></b>() <font color="#990000">::</font> #{
<font color="#0000FF">reply_to</font> <font color="#990000">=></font> <b><font color="#000080">pid</font></b>()
}</tt></pre>
</div></div>
<p>Configuration for a particular request.</p>
<p>The default value is given next to the option name:</p>
<dl><dt>reply_to (<code>self()</code>)</dt>
<dd><p>The pid of the process that will receive the response messages.</p>
</dd>
</dl>
<h3 id="_ws_opts">ws_opts()</h3>
<div class="listingblock"><div class="content"><!-- Generator: GNU source-highlight 3.1.9
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><tt><b><font color="#000000">ws_opts</font></b>() <font color="#990000">::</font> #{
<font color="#0000FF">compress</font> <font color="#990000">=></font> <b><font color="#000000">boolean</font></b>()
}</tt></pre>
</div></div>
<p>Configuration for the Websocket protocol.</p>
<p>The default value is given next to the option name:</p>
<dl><dt>compress => boolean()</dt>
<dd><p>Whether to enable permessage-deflate compression. This does not guarantee that compression will be used as it is the server that ultimately decides. Defaults to false.</p>
</dd>
</dl>
<!-- @todo Document default_protocol, protocols and user_opts.-->
<h2 id="_see_also">See also</h2>
<p><a href="..">gun(7)</a></p>
</div>
<div class="span3 sidecol">
<h3>
Gun
1.0
Function Reference
</h3>
<ul>
<li><a href="/docs/en/gun/1.0/guide">User Guide</a></li>
<li><a href="/docs/en/gun/1.0/manual">Function Reference</a></li>
</ul>
<h4 id="docs-nav">Navigation</h4>
<h4>Version select</h4>
<ul>
<li><a href="/docs/en/gun/2.0/manual">2.0</a></li>
<li><a href="/docs/en/gun/1.3/manual">1.3</a></li>
<li><a href="/docs/en/gun/1.2/manual">1.2</a></li>
<li><a href="/docs/en/gun/1.1/manual">1.1</a></li>
<li><a href="/docs/en/gun/1.0/manual">1.0</a></li>
</ul>
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