Client Runtime Support

Client runtime support is provided in libraries that you link with when building Message Queue clients. You can think of the client runtime as the bit of the Message Queue service that becomes part of the client. For example, when client code makes an API call to send a message, code in these libraries is invoked that packages the message bits appropriately for the protocol that will be used to relay the message to the physical destination on the broker.

Java and C Client Support

A JMS provider is only required to support Java clients; however, as Figure 1–6 shows, a Message Queue client can use either the Java or a provider-specific C API to send or receive a message. These interfaces are implemented in Java or C runtime libraries, which do the actual work of creating connections to the broker and packaging the bits appropriately for the connection service requested.

• The Java client runtime supplies Java clients with the objects needed to interact with the broker. These objects include connections, sessions, messages, message producers, and message consumers.

• The C client runtime supplies C clients with the functions and structures needed to interact with the broker. It supports a procedural version of the JMS programming model. C clients cannot use JNDI to access administered objects, but can create connection factories and destinations programmatically.

The Message Queue service provides a C API to enable legacy C and C++ applications to participate in JMS-based messaging. There are a number of differences in the functionality provided by these two APIs; these are documented in Java and C Clients.

It is important to remember that the JMS specification is a standard for Java clients only. C support is specific to the Message Queue provider and should not be used in client applications that you plan to port to other providers.

SOAP Support for Java Clients

Message Queue Java clients are also able to send and receive SOAP messages, wrapped as JMS messages. SOAP (Simple Object Access Protocol) allows the exchange of structured data between two peers in a distributed environment. The data exchanged is specified by an XML scheme.

Sun SOAP processing is currently limited to using a point-to-point model and does not guarantee reliability. By wrapping a SOAP message in a JMS message and routing it using the broker, you can take advantage of full featured Message Queue messaging which guarantees reliable delivery and allows you to use the topic as well as the point-to-point domain. Message Queue provides utility routines that a message producer can use to wrap a SOAP message into a JMS message and that a message consumer can use to extract a SOAP message from the JMS message.

Working with SOAP Messages gives you a more detailed view of SOAP message processing.