Cloud PubSub Client - Class Topic (1.44.0)

Reference documentation and code samples for the Cloud PubSub Client class Topic.

A named resource to which messages are sent by publishers.

Example:

use Google\Cloud\PubSub\PubSubClient;

$pubsub = new PubSubClient();
$topic = $pubsub->topic('my-new-topic');

// You can also pass a fully-qualified topic name:
$topic = $pubsub->topic('projects/my-awesome-project/topics/my-new-topic');

Namespace

Google \ Cloud \ PubSub

Methods

__construct

Create a PubSub topic.

Parameters
Name	Description
`connection`	`Google\Cloud\PubSub\Connection\ConnectionInterface` A connection to the Google Cloud Platform service
`projectId`	`string` The project Id
`name`	`string` The topic name
`encode`	`bool` Whether messages should be base64 encoded.
`info`	`array` A [Topic](https://cloud.google.com/pubsub/docs/reference/rest/v1/projects.topics
`↳ name`	`string` The name of the topic.
`↳ labels`	`array` Key value pairs used to organize your resources.
`↳ kmsKeyName`	`string` The resource name of the Cloud KMS CryptoKey to be used to protect access to messages published on this topic. The expected format is `projects/my-project/locations/kr-location/keyRings/my-kr/cryptoKeys/my-key`.
`↳ enableCompression`	`bool` Flag to enable compression of messages before publishing. Set the flag to `true` to enable compression. Defaults to `false`. Messsages are compressed if their total size >= `compressionBytesThreshold`, whose default value has been experimentally derived after performance evaluations.
`↳ compressionBytesThreshold`	`int` The threshold byte size above which messages are compressed. This only takes effect if `enableCompression` is set to `true`. Defaults to `240`. (This value is experiementally derived after performance evaluations.)
`clientConfig`	`array` [optional] Configuration options for the PubSub client used to handle processing of batch items through the daemon. For valid options please see Google\Cloud\PubSub\PubSubClient::__construct(). Defaults to the options provided to the PubSub client associated with this instance.

name

Get the topic name

Example:

echo $topic->name();

Returns
Type	Description
`string`

create

Create a topic.

Example:

$topicInfo = $topic->create();

Parameters
Name	Description
`options`	`array` Configuration Options
`↳ labels`	`array` Key value pairs used to organize your resources.
`↳ kmsKeyName`	`string` The resource name of the Cloud KMS CryptoKey to be used to protect access to messages published on this topic. The expected format is `projects/my-project/locations/kr-location/keyRings/my-kr/cryptoKeys/my-key`.
`↳ messageStoragePolicy`	`array` Policy constraining the set of Google Cloud Platform regions where messages published to the topic may be stored. If not present, then no constraints are in effect.
`↳ messageStoragePolicy`	`string[]` .allowedPersistenceRegions A list of IDs of GCP regions where messages that are published to the topic may be persisted in storage. Messages published by publishers running in non-allowed GCP regions (or running outside of GCP altogether) will be routed for storage in one of the allowed regions. An empty list means that no regions are allowed, and is not a valid configuration.
`↳ schemaSettings`	`string\|Schema` .schema The name of a schema that messages published should be validated against, or an instance of Google\Cloud\PubSub\Google\Cloud\PubSub\Schema.
`↳ schemaSettings`	`string` .encoding The encoding of messages validated against schema. For allowed values, see constants defined on Google\Cloud\PubSub\Google\Cloud\PubSub\V1\Encoding}. </xref

Returns
Type	Description
`array`	Topic information

update

Update the topic.

Note that the topic's name and kms key name are immutable properties and may not be modified.

Example:

$topic->update([
    'messageStoragePolicy' => [
        'allowedPersistenceRegions' => ['us-central1']
    ]
]);

// Updating labels with an explicit update mask
$topic->update([
    'labels' => [
        'foo' => 'bar'
    ]
], [
    'updateMask' => [
        'labels'
    ]
]);

Parameters
Name	Description
`topic`	`array` The Topic data.
`↳ labels`	`array` Key value pairs used to organize your resources.
`↳ messageStoragePolicy`	`array` Policy constraining the set of Google Cloud Platform regions where messages published to the topic may be stored. If not present, then no constraints are in effect.
`↳ messageStoragePolicy`	`string[]` .allowedPersistenceRegions A list of IDs of GCP regions where messages that are published to the topic may be persisted in storage. Messages published by publishers running in non-allowed GCP regions (or running outside of GCP altogether) will be routed for storage in one of the allowed regions. An empty list means that no regions are allowed, and is not a valid configuration.
`↳ schemaSettings`	`string\|Schema` .schema The name of a schema that messages published should be validated against, or an instance of Google\Cloud\PubSub\Google\Cloud\PubSub\Schema.
`↳ schemaSettings`	`string` .encoding The encoding of messages validated against schema. For allowed values, see constants defined on Google\Cloud\PubSub\Google\Cloud\PubSub\V1\Encoding}. </xref
`options`	`array` Configuration options.
`↳ updateMask`	`array` A list of field paths to be modified. Nested key names should be dot-separated, e.g. `messageStoragePolicy.allowedPersistenceRegions`. Google Cloud PHP will attempt to infer this value on your behalf, however modification of map fields with arbitrary keys (such as labels or message storage policy) requires an explicit update mask.

Returns
Type	Description
`array`	The topic info.

delete

Delete a topic.

Example:

$topic->delete();

Parameter
Name	Description
`options`	`array` [optional] Configuration Options

Returns
Type	Description
`void`

exists

Check if a topic exists.

Service errors will NOT bubble up from this method. It will always return a boolean value. If you want to check for errors, use Google\Cloud\PubSub\Google\Cloud\PubSub\Topic::info().

Example:

if ($topic->exists()) {
    echo 'Topic exists';
}

Parameter
Name	Description
`options`	`array` [optional] Configuration Options

Returns
Type	Description
`bool`

info

Get topic information.

Currently this resource returns only the topic name, if the topic exists. It is mostly useful therefore for checking if a topic exists.

Since this method will throw an exception if the topic is not found, you may find that Topic::exists() is a better fit for a true/false check.

This method will use the previously cached result, if available. To force a refresh from the API, use Google\Cloud\PubSub\Google\Cloud\PubSub\Topic::reload().

Example:

$info = $topic->info();
echo $info['name']; // projects/my-awesome-project/topics/my-new-topic

Parameter
Name	Description
`options`	`array` [optional] Configuration Options

Returns
Type	Description
`array`	[A representation of a Topic](https://cloud.google.com/pubsub/docs/reference/rest/v1/projects.topics)

reload

Get topic information from the API.

Currently this resource returns only the topic name, if the topic exists. It is mostly useful therefore for checking if a topic exists.

Since this method will throw an exception if the topic is not found, you may find that Topic::exists() is a better fit for a true/false check.

This method will retrieve a new result from the API. To use a previously cached result, if one exists, use Google\Cloud\PubSub\Google\Cloud\PubSub\Topic::info().

Example:

$topic->reload();
$info = $topic->info();
echo $info['name']; // projects/my-awesome-project/topics/my-new-topic

Parameter
Name	Description
`options`	`array` [optional] Configuration Options

Returns
Type	Description
`array`	[A representation of a Topic](https://cloud.google.com/pubsub/docs/reference/rest/v1/projects.topics)

publish

Publish a new message to the topic.

$message must provide at least one of data and attributes members.

Example:

$topic->publish([
    'data' => 'New User Registered',
    'attributes' => [
        'id' => '1',
        'userName' => 'John',
        'location' => 'Detroit'
    ]
]);

Parameters
Name	Description
`message`	`Google\Cloud\PubSub\Message\|array` An instance of Google\Cloud\PubSub\Google\Cloud\PubSub\Message, or an array in the correct Message Format.
`options`	`array` [optional] Configuration Options

Returns
Type	Description
`array`	A list of message IDs

publishBatch

Publish multiple messages at once.

Note that if ordering keys are provided, all members of given messages set must provide the same ordering key. Multiple ordering keys in a single publish call is not supported.

Example:

$topic->publishBatch([
    [
        'data' => 'New User Registered',
        'attributes' => [
            'id' => '1',
            'userName' => 'John',
            'location' => 'Detroit'
        ]
    ], [
        'data' => 'New User Registered',
        'attributes' => [
            'id' => '2',
            'userName' => 'Steve',
            'location' => 'Mountain View'
        ]
    ]
]);

Parameters
Name	Description
`messages`	`array<Google\Cloud\PubSub\Message>\|array[]` A list of messages. Each message must be in the correct Message Format, or be an instance of Google\Cloud\PubSub\Google\Cloud\PubSub\Message.
`options`	`array` [optional] Configuration Options

Returns
Type	Description
`array`	A list of message IDs.

batchPublisher

Push a message into a batch queue, to be processed at a later point.

Example:

$topic->batchPublisher()
    ->publish([
        'data' => 'New User Registered',
        'attributes' => [
            'id' => '2',
            'userName' => 'Dave',
            'location' => 'Detroit'
        ]
    ]);

Parameters
Name	Description
`options`	`array` Configuration options.
`↳ debugOutput`	`bool` Whether or not to output debug information. Please note debug output currently only applies in CLI based applications. Defaults to `false`.
`↳ debugOutputResource`	`resource` A resource to output debug output to. Defaults to Resource for `php://stderr`.
`↳ batchOptions`	`array` A set of options for a BatchJob. Google\Cloud\Core\Batch\BatchJob::__construct() for more details. Defaults to ['batchSize' => 1000, 'callPeriod' => 2.0, 'numWorkers' => 2].
`↳ clientConfig`	`array` Configuration options for the PubSub client used to handle processing of batch items. For valid options please see Google\Cloud\PubSub\PubSubClient::__construct(). Defaults to the options provided to the client associated with the current `Topic` instance.
`↳ batchRunner`	`BatchRunner` A BatchRunner object. Mainly used for the tests to inject a mock. Defaults to a newly created BatchRunner.
`↳ identifier`	`string` An identifier for the batch job. Defaults to `pubsub-topic-{topic-name}`. Example: `pubsub-topic-mytopic`.
`↳ closureSerializer`	`ClosureSerializerInterface` An implementation responsible for serializing closures used in the `$clientConfig`. This is especially important when using the batch daemon. Defaults to Google\Cloud\PubSub\Google\Cloud\Core\Batch\OpisClosureSerializer if the `opis/closure` library is installed.
`↳ enableCompression`	`bool` Flag to enable compression of messages before publishing. Set the flag to `true` to enable compression. Defaults to `false`. Messsages are compressed if their total size >= `compressionBytesThreshold`, whose default value has been experimentally derived after performance evaluations.
`↳ compressionBytesThreshold`	`int` The threshold byte size above which messages are compressed. This only takes effect if `enableCompression` is set to `true`. Defaults to `240`. (This value is experiementally derived after performance evaluations.)

Returns
Type	Description
`Google\Cloud\PubSub\BatchPublisher`

Create a subscription to the topic.

Example:

$subscription = $topic->subscribe('my-new-subscription');

Parameters
Name	Description
`name`	`string` The subscription name
`options`	`array` [optional] Please see Google\Cloud\PubSub\Google\Cloud\PubSub\Subscription::create() for configuration details.

Returns
Type	Description
`Google\Cloud\PubSub\Subscription`

subscription

This method will not run any API requests. You will receive a Subscription object that you can use to interact with the API.

Example:

$subscription = $topic->subscription('my-new-subscription');

Parameter
Name	Description
`name`	`string` The subscription name

Returns
Type	Description
`Google\Cloud\PubSub\Subscription`

subscriptions

Retrieve a list of active subscriptions to the current topic.

Example:

$subscriptions = $topic->subscriptions();
foreach ($subscriptions as $subscription) {
    echo $subscription->name();
}

Parameters
Name	Description
`options`	`array` Configuration Options
`↳ pageSize`	`int` Maximum number of subscriptions to return.
`↳ resultLimit`	`int` Limit the number of results returned in total. Defaults to `0` (return all results).
`↳ pageToken`	`string` A previously-returned page token used to resume the loading of results from a specific point.

Returns
Type	Description
`Google\Cloud\Core\Iterator\ItemIterator<\google\cloud\pubsub\subscription>`

iam

Manage the IAM policy for the current Topic.

Example:

$iam = $topic->iam();

Returns
Type	Description
`Google\Cloud\Core\Iam\Iam`

__debugInfo

Present a nicer debug result to people using php 5.6 or greater.

Returns
Type	Description
`array`

Constants

DEFAULT_COMPRESSION_BYTES_THRESHOLD

Value: 240

DEFAULT_ENABLE_COMPRESSION

Value: false