Chapter 54. JavaSpace
JavaSpace Component
The javaspace component is a transport for working with any JavaSpace compliant implementation and this component has been tested with both the Blitz implementation and the GigaSpace implementation. This component can be used for sending and receiving any object inheriting from the Jini
net.jini.core.entry.Entry class. It is also possible to pass the bean ID of a template that can be used for reading/taking the entries from the space. This component can be used for sending/receiving any serializable object acting as a sort of generic transport. The JavaSpace component contains a special optimization for dealing with the BeanExchange. It can be used to invoke a POJO remotely, using a JavaSpace as a transport. This latter feature can provide a simple implementation of the master/worker pattern, where a POJO provides the business logic for the worker. Look at the test cases for examples of various use cases for this component.
URI format
javaspace:jini://host[?options]
You can append query options to the URI in the following format,
?option=value&option=value&...
Options
| Name | Default Value | Description |
|---|---|---|
spaceName
|
null
|
Specifies the JavaSpace name. |
verb
|
take
|
Specifies the verb for getting JavaSpace entries. The values can be: take or read.
|
transactional
|
false
|
If true, sending and receiving entries is performed within a transaction.
|
transactionalTimeout
|
Long.MAX_VALUE
|
Specifies the transaction timeout. |
concurrentConsumers
|
1
|
Specifies the number of concurrent consumers getting entries from the JavaSpace. |
templateId
|
null
|
If present, this option specifies the Spring bean ID of the template to use for reading/taking entries. |
Sending and Receiving Entries
//Sending route
from("direct:input").to("javaspace:jini://localhost?spaceName=mySpace");
//Receiving Route
from("javaspace:jini://localhost?spaceName=mySpace&templateId=template&verb=take&concurrentConsumers=1")
In this case the payload can be any object that inherits from the Jini
Entry type.
Sending and receiving serializable objects
Using the preceding routes, it is also possible to send and receive any serializable object. The JavaSpace component detects that the payload is not a Jini
Entry and then it automatically wraps the payload with a Camel Jini Entry. In this way, a JavaSpace can be used as a generic transport mechanism.
Using JavaSpace as a remote invocation transport
The JavaSpace component has been tailored to work in combination with the Camel bean component. It is therefore possible to call a remote POJO using JavaSpace as the transport:
from("direct:input").to("javaspace:jini://localhost?spaceName=mySpace"); //Client side
from("javaspace:jini://localhost?concurrentConsumers=10&spaceName=mySpace").to("pojo:pojo"); //Server side
In the code there are two test cases showing how to use a POJO to realize the master/worker pattern. The idea is to use the POJO to provide the business logic and rely on Apache Camel for sending/receiving requests/replies with the proper correlation.
