# Adapters

`Zend_Queue` supports all queues implementing the interface `Zend_Queue_Adapter_AdapterInterface`. The following Message Queue services are supported:

- Apache ActiveMQ.

- A database driven queue via `Zend_Db`.

- A MemcacheQ queue driven via `Memcache`.

- Zend Platform's Job Queue.

- A local array. Useful for unit testing.

## Limitations

Message transaction handling is not supported.

## Specific Adapters - Configuration settings

If a default setting is indicated then the parameter is optional. If a default setting is not specified then the parameter is required.

### Apache ActiveMQ - Zend_Queue_Adapter_Activemq

Options here listed here are known requirements. Not all messaging servers require username or password.

- $options['name'] = '/temp/queue1';

  This is the name of the queue that you wish to start using. (Required)

- $options['driverOptions']['host'] = 'host.domain.tld';

  $options['driverOptions']['host'] = '127.0.0.1';

  You may set host to an IP address or a hostname.

  Default setting for host is '127.0.0.1'.

- $options['driverOptions']['port'] = 61613;

  Default setting for port is 61613.

- $options['driverOptions']['username'] = 'username';

  Optional for some messaging servers. Read the manual for your messaging server.

- $options['driverOptions']['password'] = 'password';

  Optional for some messaging servers. Read the manual for your messaging server.

- $options['driverOptions']['timeout_sec'] = 2;

  $options['driverOptions']['timeout_usec'] = 0;

  This is the amount of time that `Zend_Queue_Adapter_Activemq` will wait for read activity on a socket before returning no messages.

### Db - Zend_Queue_Adapter_Db

Driver options are checked for a few required options such as type, host, username, password, and dbname. You may pass along additional parameters for `Zend_DB::factory()` as parameters in `$options['driverOptions']`. An example of an additional option not listed here, but could be passed would be port.

    $options = array(
        'driverOptions' => array(
            'host'      => 'db1.domain.tld',
            'username'  => 'my_username',
            'password'  => 'my_password',
            'dbname'    => 'messaging',
            'type'      => 'pdo_mysql',
            'port'      => 3306, // optional parameter.
        ),
        'options' => array(
            // use Zend_Db_Select for update, not all databases can support this
            // feature.
            Zend_Db_Select::FOR_UPDATE => true
        )
    );

    // Create a database queue.
    $queue = new Zend_Queue('Db', $options);

- $options['name'] = 'queue1';

  This is the name of the queue that you wish to start using. (Required)

- $options['driverOptions']['type'] = 'Pdo';

  type is the adapter you wish to have `Zend_Db::factory()` use. This is the first parameter for the `Zend_Db::factory()` class method call.

- $options['driverOptions']['host'] = 'host.domain.tld';

  $options['driverOptions']['host'] = '127.0.0.1';

  You may set host to an IP address or a hostname.

  Default setting for host is '127.0.0.1'.

- $options['driverOptions']['username'] = 'username';

- $options['driverOptions']['password'] = 'password';

- $options['driverOptions']['dbname'] = 'dbname';

  The database name that you have created the required tables for. See the notes section below.

### MemcacheQ - Zend_Queue_Adapter_Memcacheq

- $options['name'] = 'queue1';

  This is the name of the queue that you wish to start using. (Required)

- $options['driverOptions']['host'] = 'host.domain.tld';

  $options['driverOptions']['host'] = '127.0.0.1;'

  You may set host to an IP address or a hostname.

  Default setting for host is '127.0.0.1'.

- $options['driverOptions']['port'] = 22201;

  The default setting for port is 22201.

### Zend Platform Job Queue - Zend_Queue_Adapter_PlatformJobQueue

- $options['daemonOptions']['host'] = '127.0.0.1:10003';

  The hostname and port corresponding to the Zend Platform Job Queue daemon you will use. (Required)

- $options['daemonOptions']['password'] = '1234';

  The password required for accessing the Zend Platform Job Queue daemon. (Required)

### Array - Zend_Queue_Adapter_Array

- $options['name'] = 'queue1';

  This is the name of the queue that you wish to start using. (Required)

## Notes for Specific Adapters

The following adapters have notes:

### Apache ActiveMQ

Visibility duration for `Zend_Queue_Adapter_Activemq` is not available.

While Apache's ActiveMQ will support multiple subscriptions, the `Zend_Queue` does not. You must create a new `Zend_Queue` object for each individual subscription.

ActiveMQ queue/topic names must begin with one of:

- `/queue/`

- `/topic/`

- `/temp-queue/`

- `/temp-topic/`

For example: `/queue/testing`

The following functions are not supported:

- `create()` - create queue. Calling this function will throw an exception.

- `delete()` - delete queue. Calling this function will throw an exception.

- `getQueues()` - list queues. Calling this function will throw an exception.

### Zend_Db

The database CREATE TABLE ( ... ) SQL statement can be found in `Zend/Queue/Adapter/Db/queue.sql`.

### MemcacheQ

Memcache can be downloaded from http://www.danga.com/memcached/.

MemcacheQ can be downloaded from http://memcachedb.org/memcacheq/.

- `deleteMessage()` - Messages are deleted upon reception from the queue. Calling this function would have no effect. Calling this function will throw an error.

- `count()` or `count($adapter)` - MemcacheQ does not support a method for counting the number of items in a queue. Calling this function will throw an error.

### Zend Platform Job Queue

Job Queue is a feature of Zend Platform's Enterprise Solution offering. It is not a traditional message queue, and instead allows you to queue a script to execute, along with the parameters you wish to pass to it. You can find out more about Job Queue on the zend.com website.

The following is a list of methods where this adapter's behavior diverges from the standard offerings:

- `create()` - Zend Platform does not have the concept of discrete queues; instead, it allows administrators to provide scripts for processing jobs. Since adding new scripts is restricted to the administration interface, this method simply throws an exception indicating the action is forbidden.

- `isExists()` - Just like `create()`, since Job Queue does not have a notion of named queues, this method throws an exception when invoked.

- `delete()` - similar to `create()`, deletion of JQ scripts is not possible except via the admin interface; this method raises an exception.

- `getQueues()` - Zend Platform does not allow introspection into the attached job handling scripts via the API. This method throws an exception.

- `count()` - returns the total number of jobs currently active in the Job Queue.

- `send()` - this method is perhaps the one method that diverges most from other adapters. The `$message` argument may be one of three possible types, and will operate differently based on the value passed:

  - string - the name of a script registered with Job Queue to invoke. If passed in this way, no arguments are provided to the script.

  - array - an array of values with which to configure a `ZendApi_Job` object. These may include the following:

    - `script` - the name of the Job Queue script to invoke. (Required)

    - `priority` - the job priority to use when registering with the queue.

    - `name` - a short string describing the job.

    - `predecessor` - the ID of a job on which this one depends, and which must be executed before this one may begin.

    - `preserved` - whether or not to retain the job within the Job Queue history. By default, off; pass a true value to retain it.

    - `user_variables` - an associative array of all variables you wish to have in scope during job execution (similar to named arguments).

    - `interval` - how often, in seconds, the job should run. By default, this is set to 0, indicating it should run once, and once only.

    - `end_time` - an expiry time, past which the job should not run. If the job was set to run only once, and `end_time` has passed, then the job will not be executed. If the job was set to run on an interval, it will not execute again once `end_time` has passed.

    - `schedule_time` - a UNIX timestamp indicating when to run the job; by default, 0, indicating the job should run as soon as possible.

    - `application_id` - the application identifier of the job. By default, this is null, indicating that one will be automatically assigned by the queue, if the queue was assigned an application ID.

    As noted, only the `script` argument is required; all others are simply available to allow passing more fine-grained detail on how and when to run the job.

  - `ZendApi_Job` - finally, you may simply pass a `ZendApi_Job` instance, and it will be passed along to Platform's Job Queue.

  In all instances, `send()` returns a `Zend_Queue_Message_PlatformJob` object, which provides access to the `ZendApi_Job` object used to communicate with Job Queue.

- `receive()` - retrieves a list of active jobs from Job Queue. Each job in the returned set will be an instance of `Zend_Queue_Message_PlatformJob`.

- `deleteMessage()` - since this adapter only works with Job Queue, this method expects the provided `$message` to be a `Zend_Queue_Message_PlatformJob` instance, and will throw an exception otherwise.

### Array (local)

The Array queue is a PHP `array()` in local memory. The `Zend_Queue_Adapter_Array` is good for unit testing.