docs/user-manual/modules/ROOT/pages/uuidgenerator.adoc

[[UuidGenerator-UuidGenerator]]
= UuidGenerator

Starting with *Camel 2.5*, Camel supports 3rd party UUID generator(s).
This is useful, if e.g. your messaging provider does not support UUID's
with a length of 36 characters (like Websphere MQ). Another useful
scenario is to use a simple counter for testing purpose. With this it is
easier to correlate the exchanges in the log/debugger.

Camel uses UUIDs in the exchange and message ids, and other unique ids
it uses.

You only have to implement `org.apache.camel.spi.UuidGenerator` and tell
Camel, that it should use your custom implementation:

[[UuidGenerator-ConfiguringfromJavaDSL]]
== Configuring from Java DSL

[source,java]
-----------------------------------------------------------
getContext().setUuidGenerator(new MyCustomUuidGenerator());
-----------------------------------------------------------

Warning: You should not change the UUID generator at runtime (it should only be
set once)!

[[UuidGenerator-ConfiguringfromSpringDSL]]
== Configuring from Spring DSL

Camel will configure this UUID generator by doing a lookup in the Spring
bean registry to find the bean of the type
`org.apache.camel.spi.UuidGenerator`.

[source,java]
---------------------------------------------------------------------------------------
<bean id="activeMQUuidGenerator" class="org.apache.camel.impl.ActiveMQUuidGenerator" />

<camelContext id="camel" xmlns="http://camel.apache.org/schema/spring">
  <route>
    <from uri="direct:start" />
    <to uri="mock:result" />
  </route>
</camelContext>
---------------------------------------------------------------------------------------

[[UuidGenerator-Providedimplementations]]
== Provided implementations

Camel comes with three implementations of
`org.apache.camel.spi.UuidGenerator`:

* `org.apache.camel.impl.JavaUuidGenerator` - This implementation uses
`java.util.UUID`. The `java.util.UUID` is synchronized and can therefore
affect performance on high concurrent systems. Therefore consider one of
the generators.
* `org.apache.camel.impl.SimpleUuidGenerator` - This implementation use
internally a `java.util.concurrent.atomic.AtomicLong` and increase the
ID for every call by one. Starting with 1 as the first id.
* `org.apache.camel.impl.ActiveMQUuidGenerator` - This implementation
use the ActiveMQ style of ID's. This implementation may use some APIs
from the JDK which is forbidden to use if running in the cloud (such as
Google App Engine) and therefore you may have to use one of the other
generators.

[[UuidGenerator-ActiveMQUuidGenerator]]
== ActiveMQUuidGenerator

From *Camel 2.10.7/2.11.1* onwards the JVM system property with key:
`activemq.idgenerator.port` can be used to assign a specific port which
is used during initialization of the UUID generator. By default the port
number 0 is used. Though in some cloud infrastructures this is not
allowed, and thus a specific port can be assigned instead.

[[UuidGenerator-Thedefaultgenerator]]
== The default generator

* From Camel 2.5 onwards the `ActiveMQUuidGenerator` is the default
generator because its the fastest. 
* In Camel 2.4 or older the default is the `JavaUuidGenerator`
generator.