PHP API

USING RIAK WITH PHP
Front Range PHP Users Group - May 12th, 2010
Jon Meredith - Basho Technologies
jmeredith@basho.com / @jon_meredith

RIAK BY EXAMPLE

• URL Shortener Example in PHP (thx Sean Cribbs)

• Creates a short URL that redirects to the real thing

• Demonstrates buckets, get and put.

<html>
SUBMIT-TO-SELF FORM
<h1>URL Shortener</h1>
<form method="post" action="<?php echo $_SERVER['PHP_SELF']; ?>">
URL <input type="text" name="url" size="60"
value="<?php echo $url; ?>">
<input type="submit" name="submit" value="Shtn!"><br/>
<?php
if (isset($shtn)) {
$surl = "http://$_SERVER[SERVER_NAME]:$_SERVER[SERVER_PORT]"+
"$_SERVER[PHP_SELF]/$shtn";
echo "Shortened <a href='$surl'>$surl</a><br/>";
}
if (isset($notice)) {
echo "<em>$notice</em><br/>";
}
?>
</form>
</html>

ON POST
<?php
include_once "riak.php";
// snip...

// Responding to a post
} elseif (isset($_POST['url'])) {
$url = $_POST['url'];
$shtn = shorten($url);

$client = new RiakClient('localhost', 8098);
$bucket = $client->bucket('shtn');
$object = $bucket->newBinary($shtn, $url, 'text/plain');
$object->store();
}
?>

ON GET
if ($_SERVER["REQUEST_METHOD"] == 'GET' and
isset($_SERVER["PATH_INFO"])) {
$client = new RiakClient('localhost', 8098);
$bucket = $client->bucket('shtn');
$path_els = explode('/', $_SERVER["PATH_INFO"]);
$key = $path_els[1];
$obj = $bucket->getBinary($key);
if ($obj->exists())
{
$lurl = $obj->getData();
header("Location: $lurl");
exit;
}
else
{
$notice = "Unknown redirect for $key";
}
}

STUPID COLLISION PRONE SHORTENER
DO NOT USE

// cheap and cheerful shortener - takes hash with crc32,
// converts to base64 and trims non a-zA-Z0-9 characters
function shorten($url) {
$hash = hash("crc32", $url, true);
$str = base64_encode($hash);
return preg_replace('/[^a-zA-Z0-9]/', '', $str);
}

RIAK & PHP

• PHP client http://bitbucket.org/basho/riak-php-client

• Uses Riak’s RESTful HTTP interface

• Pure PHP - requires the cURL module to be installed

RIAK PHP API

• RiakClient - a connection to a single server

• RiakBucket - access to bucket properties/objects stored

• RiakObject - a key/value/metadata object

RIAK MATH

•N - number of replicas

•R - number of reads

•W - number of writes

• DW - durable writes

• As long as R+W > N you read your writes

RIAKCLIENT CLASS

• Create connection to a server
$client = new RiakClient(HOST, PORT);
assert($client->isAlive());

• Create a RiakBucket object
$bucket = $client->bucket('bucket');

• Get/Change Defaults
$client->getR(); $client->getW(); $client->getDW();
$client->setR(1); $client->setW(3); client->setDW(1);
$

RIAK BUCKETS

• Buckets group related keys together.

• Finest level you can conﬁgure Riak at

•n value - number of replicas

• allow_mult - return conﬂicts to client

• r/w/dw - successful reads/writes/durable writes

RIAKBUCKET CLASS

• Retrieve objects
$obj1 = $bucket->get("missing");
$obj1 = $bucket->get("missing", $rVal);
$obj2 = $bucket->getBinary('foo2');
$obj2 = $bucket->getBinary('foo2', $rVal);

• Create Objects
$obj1 = bucket->newObject('foo', $structuredData);
$obj2 = $bucket->newBinary('foo1', $binaryData);

MORE RIAKBUCKET

• Modify bucket properties
$bucket->getAllowMultiples(); $bucket->setAllowMultiples(TRUE);
$bucket->getNVal(); $bucket->setNVal(3);

• Modify per-bucket defaults
$bucket->getR(); $bucket->getW(); $bucket->getDW();
$bucket->setR(1); $bucket->setW(3); bucket->setDW(1);
$

RIAK OBJECTS

• RiakObjects hold bucket name, keys, values and metadata.

• Metadata includes content type and links.

• By default objects serialize using JSON
... can prevent using ‘binary’ objects
$bucket->getBinary($key); $bucket->newBinary($key);

RIAKOBJECT CLASS

• Access key/data/metadata
$object->getKey(); $object->getBucket();
$object->getContentType(); $object->getLinks();
$object->getData();

• Change data/metadata
$object->setContentType($contentType);
$object->setData($data);
$object->addLink($obj2,$tag);
$object->removeLink($obj2, $tag);

MORE RIAKOBJECT

• Store on server
$obj->store();

• Reload from server
$obj->reload();

• Delete from server
$obj->delete();

• Clear contents data/metadata (but not bucket/key/vclock)
$obj->clear();

LINKS

•A Link store a one-way relationship between two objects,
similar to a hyperlink.

•A link is a bucket & key plus a user-supplied tag.

• Objects can have multiple links.

• Riak
supports link walking - server side
- match on bucket or tag

LINKS EXAMPLE

people/alice vip/claire
friend

[no tag] [no tag] friend

friend

people/bob people/dean Images http://www.openclipart.org

CREATING LINKS

• Create objects with some links
$people = $client->bucket('people');
$vips = $client->bucket('vips');
$alice = $people->newObject("alice", array(name => 'Alice'))->store();
$bob = $people->newObject("bob", array(name => 'Bob'))->store();
$claire = $vip->newObject("claire", array(name => 'Claire'))->
addLink($alice, 'friend')->
store();
$dean = $people->newObject("dean", array(name => 'Dean'))->
addLink($alice)->
addLink($bob, 'friend')->
addLink($claire, 'friend')->
addLink($claire)->
store();

LINK WALKING
• Walk the links
$resultObjects = $object->link($bucket='_', $tag='_', $keep=FALSE);
$bucket - match on a bucket name, '_' matches all
$tag - match on a link tag, '_' matches all
$keep - return results - last link always TRUE.

• Examples
// Dean’s links array of $alice, $bob, $claire, $claire (duplicate)
$deans_links = $dean->link('_')->run();
// Dean’s friends array of $bob, $claire
$deans_friends = $dean->link('_','friend')->run();
// Dean’s VIPs array of $claire
$deans_vips = $dean->link('vip’)->run();
// Friends of Dean’s friends array of $alice
$deans_fofs = $dean->link('_','friend')->link('_','friend')->run();
// friends within 2 degrees of separation - array(array($bob, $claire), $alice)
$deans_2degs = $dean->link('_','friend', TRUE)->link('_','friend', TRUE)->run();

LINK WALKING DEMO

• http://github.com/schoﬁeld/riak_php_app

• Created by Grant Schoﬁeld, Developer Advocate @ Basho

RIAK MAP/REDUCE

• Map/Reduce allows you to query Riak

• Map function selects/transforms data you want

• Reduce function combines the output of the map function

• Provide your own functions (in erlang or javascript) or use the
builtins

MAP/REDUCE EXAMPLE

$bucket->newObject("foo", 2)->store();
$bucket->newObject("bar", 3)->store();
$bucket->newObject("baz", 4)->store();

# Run the map...
$result = $client->
add($bucket->name)->
map("Riak.mapValuesJson") ->
reduce("Riak.reduceSum")->
run();
test_assert($result == array(9));

SUPPLY YOUR OWN MAPS
• Javascript map functions get passed an object
{
"bucket":BucketAsString,
"key":KeyAsString,
"vclock":VclockAsString,
"values":[{"metadata":{"X-Riak-VTag":VtagAsString,
"X-riak-Last-Modiﬁed":LastModAsString,
...other metadata...
},
"data":ObjectData
},
...other metadata/data values (siblings)...]
}

• Returns an array of results

RETURNS KEYS WITH SPACES
$map = "function(obj) {
if (obj.key.indexOf(' ') != -1) {
return [obj.key];
} else {
return [];
}
}";
$result = $client->
map($map) ->
reduce("Riak.reduceSort")->
run();

SUPPLY YOUR OWN REDUCE
$reduceMax = "function(values, arg) {
values.sort().reverse();
return [values[0]];
}";
$result = $client->
map("Riak.mapValuesJson") ->
reduce($reduceMax)->
run();

OVER TO YOU...

• Website http://riak.basho.com

• Mailing list riak-users@basho.com

• #riak on FreeNode

• Twitter @basho (and it follows our devs)

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