The WebSphere MQ family includes many products, offering a range of capabilities, as illustrated in Figure 1.
Figure 1. The WebSphere MQ family
Both WebSphere MQ Workflow and WebSphere MQ Integrator products take advantage of the connectivity provided by the WebSphere MQ messaging layer.
Messaging, irrespective of the particular product or product group, is based on queues and queue managers. Queue managers manage queues that can store messages. Applications communicate with a local queue manager, and get or put messages to queues. If a message is put to a remote queue (a queue owned by another queue manager), the message is transmitted over connections to the remote queue manager. In this way, messages can hop through one or more intermediate queue managers before reaching their destination. The essence of messaging is to uncouple the sending application from the receiving application, queuing messages at intermediate points, if necessary.
WebSphere MQ and WebSphere MQ Everyplace supply WebSphere MQ family messaging. Both are designed to support one or more hardware server platforms and most associated operating systems. Given the wide variety in platform capabilities, these individual products are organized into product groups, reflecting common function and design:
WebSphere MQ host and distributed messaging products are used to support many different network configurations, all of which involve clients and servers, some examples of which are illustrated in Figure 2.
Figure 2. Simple host and distributed configurations
In Figure 2:
A distributed client/server configuration involves multiple servers. In this case, servers exchange messages through unidirectional connections called message channels. Message channels assure safe and asynchronous exchange of message data. Message channels do not need to be available for the clients to continue processing. However, no messages can flow between servers when there are no communication links established between servers.
WebSphere MQ Everyplace supports a variety of network configurations. There is no concept of a client or a server as in the WebSphere MQ host or distributed products. Instead, you can configure WebSphere MQ Everyplace queue managers to act as clients or servers, enabling them to perform application-defined tasks.
An example of tailored configuration is that you can give WebSphere MQ Everyplace the ability to exchange messages with WebSphere MQ host queue managers. To do this, configure a WebSphere MQ Everyplace queue manager with bridge capabilities. Without the bridge, a queue manager can communicate directly with other WebSphere MQ Everyplace queue managers only. However, it can communicate indirectly through other queue managers in the network that have bridge capabilities.