58 lines
1.7 KiB
Markdown
58 lines
1.7 KiB
Markdown
# Exclusive Queues
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Exclusive queues are special queues which dispatch all messages to only one
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consumer at a time.
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This is useful when you want all messages to be processed _serially_ but you
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can't or don't want to use [Message Grouping](message-grouping.md).
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An example might be orders sent to an address and you need to consume them
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in the exact same order they were produced.
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Obviously exclusive queues have a draw back that you cannot scale out the
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consumers to improve consumption as only one consumer would technically be active.
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Here we advise that you look at message groups first.
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## Configuring Exclusive Queues
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Exclusive queues can be statically configured using the `exclusive` boolean
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property:
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```xml
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<address name="foo.bar">
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<multicast>
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<queue name="orders1" exclusive="true"/>
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</multicast>
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</address>
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```
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Specified on creating a Queue by using the CORE api specifying the parameter
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`exclusive` to `true`.
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Or on auto-create when using the JMS Client by using address parameters when
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creating the destination used by the consumer.
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```java
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Queue queue = session.createQueue("my.destination.name?exclusive=true");
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Topic topic = session.createTopic("my.destination.name?exclusive=true");
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```
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Also the default for all queues under and address can be defaulted using the
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`address-setting` configuration:
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```xml
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<address-setting match="lastValueQueue">
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<default-exclusive-queue>true</default-exclusive-queue>
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</address-setting>
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```
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By default, `default-exclusive-queue` is `false`. Address
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[wildcards](wildcard-syntax.md) can be used to configure exclusive queues for a
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set of addresses.
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## Example
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See the [exclusive queue example](examples.md#exclusive) which shows how
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exclusive queues are configured and used with JMS.
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