IBM BS029ML - WebSphere Portal Server Self Help Manual page 26

inter-enterprise communication, or adopted as an enterprise wide standard for leveraging an
ESB, for example. Web services are not built to be high performing, so are not suitable for
transactions that require very large throughput.
Messaging
Messaging interfaces such as WebSphere MQ and JMS are based on the asynchronous
exchange of messages between producers and consumers. Point-to-Point and
Publish-Subscribe communication patterns are provided. Messages are placed on a queue
by the sending application, and those messages are then consumed by a receiving
application. With messaging, you take advantage of a simple and common API. You adopt
industry-standard programming models and you make these available on a selection of
operating systems. Messaging provides assured delivery for business critical information.
Messaging provides asynchronous (as well as synchronous) processing for loose coupling of
applications and control of the rate at which information is processed.
Adapters
Adapters provide access to business logic in a tightly coupled manner. An adapter is specific
to a particular Enterprise Information System (EIS) and generally requires client code to be
written to parse the proprietary format of the data provided by the EIS. However, this tight
coupling allows an adapter to map security, transaction information, and other Quality of
Service information between the client and the EIS based on the well-established capabilities
of EIS gateways. While adapters typically provide a synchronous interface, the latest
specifications define an asynchronous mode as well, and some adapters implement this
mode.
Table 2-1 gives you some comparisons between the connectivity types.
Table 2-1 Connectivity comparisons
Interface Coupling
Transport Coupling
Implementation
Portability
Security
Transaction Support
Synchronous
Invocation
Asynchronous
Invocation
Event Driven
Reliable Payload
Delivery
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IBM WebSphere Portal V6 Self Help Guide
Web Services Messaging
Tight. No. An application may
process a variety of
messages.
Loose. Tight.
Yes. Yes.
Standards defined - Vendor-specific.
Not universally
implemented.
Standards defined - Limited in scope to
Not universally queue entry point.
implemented.
Yes. Custom
implementation.
Yes. Yes.
Yes. Yes.
Standard Defined. Yes.
Adapters
Tight.
Tight.
No.
EIS-specific.
Yes.
No.
EIS-specific.
EIS-specific.
EIS-specific -
Functionality provided
by actual adapters.