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<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>Farwest Demo</title>
<meta name="description" content"Farwest Demo BEAM FOSDEM 2020 talk">
<meta name="author" content="Loïc Hoguin">
<link rel="stylesheet" href="css/reveal.css">
<link rel="stylesheet" href="css/theme/black.css">
</head>
<body>
<div class="reveal">
<div class="slides">
<section>
<h1>Farwest Demo</h1>
<p>An overview and a demo of the Farwest project</p>
<p><small>Loïc Hoguin, <a href="https://ninenines.eu">Nine Nines</a></small></p>
</section>
<section>
<h1>What is Farwest?</h1>
</section>
<section>
<h2>Erlang/OTP REST framework</h2>
<p>HATEOAS</p>
<p>Standards based (whenever possible)</p>
<p>Built on top of <code>cowboy_rest</code></p>
</section>
<section>
<h2>Building blocks</h2>
<ul>
<li>Resource modules</li>
<li>URI and URI Templates (RFC 6570)</li>
<li>Media types</li>
<li>Operations (forms)</li>
<li>Metadata</li>
</ul>
</section>
<section>
<h2>Client libraries</h2>
<p>One library per language/platform</p>
<p>Build on top of existing HTTP clients</p>
<p>Don't write a separate client per API</p>
</section>
<section>
<h1>Work done so far</h1>
</section>
<section>
<h2>Discovery</h2>
<ul>
<li>Link HTTP header (RFC 8288)</li>
<li>Links in response bodies</li>
<li>URI Templates router, reverse routing</li>
<li>Variants (draft)</li>
<li>Skeleton Erlang/OTP client library</li>
</ul>
</section>
<section>
<h2>Generate response bodies</h2>
<ul>
<li>Automatic HTML generation</li>
<li>Skeleton forms</li>
<li>Automatic BED (binary Erlang data) generation</li>
</ul>
</section>
<section>
<h2>Mod:describe()</h2>
<ul>
<li>URI or URI Template</li>
<li>Operations</li>
<li>Operation/media type pairs (input/output)</li>
<li>Links</li>
</ul>
</section>
<section>
<h2>Configurable operations</h2>
<ul>
<li>HTTP method used</li>
<li>Semantics (not yet enforced)</li>
</ul>
</section>
<section>
<h1>Demo</h1>
<section>
<ol>
<li><code>git clone https://github.com/ninenines/farwest_demo</code></li>
<li><code>cd farwest_demo</code></li>
<li><code>make run</code></li>
<li>Open <a href="http://localhost:8080">http://localhost:8080</a> in your browser</li>
<li>Use <code>curl -i http://localhost:8080</code></li>
</ol>
</section>
<section>
<pre><code data-trim data-noescape>
describe() → #{
uri ⇒ "/",
media_types ⇒ #{
html ⇒ ["text/html"],
bed ⇒ ["application/x-bed"]
},
operations ⇒ #{
get ⇒ #{output ⇒ [html, bed]}
}
}.
</code></pre>
</section>
<section>
<pre><code data-trim data-noescape>
links(Req) →
{ok, [
{child, fwd_processes_r},
{child, fwd_tables_r}
], Req}.
</code></pre>
</section>
<section>
<pre><code data-trim data-noescape>
$ curl -I http://localhost:8080
HTTP/1.1 200 OK
content-length: 2398
content-type: text/html
date: Mon, 27 Jan 2020 11:56:23 GMT
link: </processes>; rel="child";
variants-06="accept=(\"text/html\" \"application/x-bed\")",
</tables>; rel="child"; variants-06="accept=(\"text/html\")"
server: Cowboy
variant-key-06: ("text/html")
variants-06: accept=("text/html" "application/x-bed")
vary: accept
</code></pre>
</section>
<section>
<pre><code data-trim data-noescape>
get(Req) →
Info = observer_backend:sys_info(),
Data = #{
«"System Version"» ⇒ g(otp_release, Info),
...
},
{ok, Data, Req}.
to_representation(Req, html, Data) →
{ok, farwest_html:from_term(Req, Data), Req};
to_representation(Req, bed, Data) →
{ok, farwest_bed:from_term(Req, Data), Req}.
</code></pre>
</section>
<section>
<img src="pics/fwd_system_r.png"/>
</section>
<section>
<pre><code data-trim data-noescape>
$ curl -I http://localhost:8080/tables
HTTP/1.1 200 OK
content-length: 7052
content-type: text/html
date: Mon, 27 Jan 2020 11:56:10 GMT
farwest-link-templates: </tables/{name}>; rel="child";
variants-06="accept=(\"text/html\")"
link: </>; rel="parent"; variants-06="accept=
(\"text/html\" \"application/x-bed\")"
server: Cowboy
</code></pre>
</section>
<section>
<img src="pics/fwd_tables_r.png"/>
</section>
<section>
<pre><code data-trim data-noescape>
{'$fw_link', child,
farwest:link_to(fwd_table_r, #{«"name"» ⇒ TableName}),
TableName}
</code></pre>
</section>
<section>
<img src="pics/fwd_table_r.png"/>
</section>
<section>
<pre><code data-trim data-noescape>
describe() → #{
uri ⇒ "/tables/{name}/{key}",
media_types ⇒ #{
html ⇒ ["text/html"],
term ⇒ ["text/plain"] %% text/x-erlang-term?
},
operations ⇒ #{
get ⇒ #{output ⇒ [html]},
put ⇒ #{input ⇒ [term]},
delete ⇒ #{}
}
}.
</code></pre>
</section>
<section>
<img src="pics/fwd_table_row_r.png"/>
</section>
<section>
<pre><code data-trim data-noescape>
put(Req0=#{bindings := #{name := Name0}}) →
Name = binary_to_atom(Name0, utf8),
{ok, Body, Req} = cowboy_req:read_body(Req0),
{ok, Tuple} = parse_string(
unicode:characters_to_list(Body) ++ "."),
ets:delete_object(Name, Tuple),
ets:insert(Name, Tuple),
{ok, Req}.
</code></pre>
</section>
<section>
<pre><code data-trim data-noescape>
delete(Req=#{bindings := #{name := Name0, key := Key0}}) →
Name = binary_to_atom(Name0, utf8),
{ok, Key} = parse_string(
unicode:characters_to_list(Key0) ++ "."),
ets:delete(Name, Key),
{ok, Req}.
</code></pre>
</section>
</section>
<section>
<h1>Upcoming work</h1>
</section>
<section>
<h2>Improved discovery</h2>
<p>Automatic sitemap?</p>
<p>External resources?</p>
<p>Link relation resources?</p>
<p>Better discovery of operations</p>
<p>Include operations/forms in non-HTML formats</p>
<p>Cache metadata (etag, cache-control...)</p>
</section>
<section>
<h2>Generate response bodies</h2>
<p>Template-based HTML generation</p>
<p>Replace/insert your own templates</p>
<p>Automatic JSON/JSON-LD/... generation</p>
</section>
<section>
<h2>Semantics</h2>
<p>Schemas (schema.org or other)</p>
<p>Better forms using schemas</p>
<p>Read data and expand URI Templates</p>
</section>
<section>
<h2>Improved client libraries</h2>
<p>More functions</p>
<p>Client-side cache for Gun</p>
<p>Non-Erlang client libraries</p>
</section>
<section>
<h1>Thanks</h1>
<p><a href="https://github.com/ninenines/farwest">github.com/ninenines/farwest</a></p>
<p><a href="https://github.com/ninenines/farwest_demo">github.com/ninenines/farwest_demo</a></p>
</section>
</div>
</div>
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