# Framework

The Zend_Queue is a proxy that hides the details of the queue services. The queue services are represented by Zend_Queue_Adapter_<service>. For example, Zend_Queue_Adapter_Db is a queue that will use database tables to store and retrieve messages.

Below is an example for using database tables for a queuing system:

    $options = array(
        'name'          => 'queue1',
        'driverOptions' => array(
            'host'      => '127.0.0.1',
            'port'      => '3306',
            'username'  => 'queue',
            'password'  => 'queue',
            'dbname'    => 'queue',
            'type'      => 'pdo_mysql'
        )
    );

    // Create a database queue.
    // Zend_Queue will prepend Zend_Queue_Adapter_ to 'Db' for the class name.
    $queue = new Zend_Queue('Db', $options);

The Zend_Queue constructor will create a Zend_Queue_Adapter_Db and initialize the adapter with the configuration settings.

The accepted configuration settings for each adapter are provided in the adapter notes.

Zend_Queue returns messages using the class Zend_Queue_Message_Iterator, which is an implementation of SPL Iterator and Countable. Zend_Queue_Message_Iterator contains an array of Zend_Queue_Message objects.

    $messages = $queue->receive(5);
    foreach ($messages as $i => $message) {
        echo "$i) Message => ", $message->body, "\n";
    }

Any exceptions thrown are of class Zend_Queue_Exception.

## Introduction

Zend_Queue is a proxy class that represents an adapter.

The send(), count($queue), and receive() methods are employed by each adapter to interact with queues.

The createQueue(), deleteQueue() methods are used to manage queues.

## Commonality among adapters

The queue services supported by Zend_Queue do not all support the same functions. For example, Zend_Queue_Adapter_Array, Zend_Queue_Adapter_Db, support all functions, while Zend_Queue_Adapter_Activemq does not support queue listing, queue deletion, or counting of messages.

You can determine what functions are supported by using Zend_Queue::isSupported() or Zend_Queue::getCapabilities().

- createQueue() - create a queue

- deleteQueue() - delete a queue

- send() - send a message

  send() is not available in all adapters; the Zend_Queue_Adapter_Null does not support send().

- receive() - receive messages

  receive() is not available in all adapters; the Zend_Queue_Adapter_Null does not support receive().

- deleteMessage() - delete a message

- count() - count the number of messages in a queue

- isExists() - checks the existence of a queue

receive() methods are employed by each adapter to interact with queues.

The createQueue() and deleteQueue() methods are used to manage queues.