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title: Using Topic Subscriptions
collection: mulesoft
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locale: en-us
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canonical_url: https://docs.mulesoft.com/ibm-mq-connector/1.7/ibm-mq-topic-subscription
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content_type: documentation
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description: MuleSoft Documentation Site
release: "1.7"
latest: false
---
---
product: IBM MQ Connector
version: 1.7
keywords: jms, ibm mq, connector, consume, source, listener, topic, subscription
---

# Using Topic Subscriptions

> For the full documentation index, see: https://docs.mulesoft.com/llms.txt

Topics in IBM MQ allow you to configure how the subscription behaves regarding the connection of the
consumer and also how these consumers interact with each other.

Using IBM MQ Connector, you can handle of the aspects of a Topic subscription using the
`topic-consumer` configuration in both the `consumer` and `listener` operations.

## Registering Durable Subscriptions

Durable subscriptions allows to receive messages that were published to the topic while the consumer
was offline. Once a durable subscription registered, each time a consumer is available it will
receive all the messages published before the connection was established:

```xml
<ibm-mq:consume config-ref="JMS_config" destination="#[vars.destination]">
    <ibm-mq:consumer-type>
        <ibm-mq:topic-consumer durable="true" subscriptionName="SampleSub"/>
    </ibm-mq:consumer-type>
</ibm-mq:consume>
```

Then IBM MQ stores the messages published to the topic, as it would store messages sent to a queue.
If this or another application creates a `topic-consumer` using the same connection and its client
ID, the same topic, and the same subscription name, the subscription is reactivated, and IBM MQ
delivers the messages that were published while the subscriber was inactive.

## Allowing Multiple Consumers on the Same Subscription

In JMS 1.1, a subscription on a topic was not permitted to have more than one consumer at a time,
meaning that the work of processing messages on a topic subscription could not be shared, thereby
limiting the scalability of the application. This restriction has been removed in JMS 2.0 by the
introduction of **shared subscriptions**.

The IBM MQ Connector, **when configured with a JMS 2.0 connection**, allows you to declare any
`topic-consumer` as part of a `shared` subscription:

```xml
<ibm-mq:listener config-ref="config" destination="InvoiceEventsTopic">
    <ibm-mq:consumer-type>
        <ibm-mq:topic-consumer shared="true" subscriptionName="ClusterSubscription"/>
    </ibm-mq:consumer-type>
</ibm-mq:listener>
```

With this configuration on two different `listener` instances, when a Message is published to the
invoices destination, it will be delivered only to one of the listeners and not the other.

## How to Ignore Self Published Messages

There are cases in which you may not want to receive the Messages that were published to a Topic by
the same application. For this cases, you can use the `noLocal` parameter in the `topic-consumer`,
thus preventing the Consumer to receive Messages published to the Topic **by the same Connection**:

```xml
<ibm-mq:listener config-ref="config" destination="${notificationsChannel}">
    <ibm-mq:consumer-type>
        <ibm-mq:topic-consumer noLocal="true"/>
    </ibm-mq:consumer-type>
</ibm-mq:listener>
```

Consumers configured as `noLocal` **can’t** be part of a `shared` subscription.

## See Also

- [To Listen For New Messages](https://docs.mulesoft.com/ibm-mq-connector/1.7/ibm-mq-listener)

- [To Consume Messages](https://docs.mulesoft.com/ibm-mq-connector/1.7/ibm-mq-consume)