IBM BS029ML Self Help Guide - Page 26

Messaging, Adapters, Web Services

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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 Web Services Interface Coupling Tight. Transport Coupling Implementation Portability Security Transaction Support Synchronous Invocation Asynchronous Invocation Event Driven Reliable Payload Delivery Loose. Yes. Standards defined Not universally implemented. Standards defined Not universally implemented. Yes. Yes. Yes. Standard Defined. Messaging Adapters No. An application may process a variety of messages. Tight. Tight. Tight. Yes. No. Vendor-specific. EIS-specific. Limited in scope to queue entry point. Custom implementation. Yes. Yes. Yes. Yes. No. EIS-specific. EIS-specific. EIS-specific Functionality provided by actual adapters. 12 IBM WebSphere Portal V6 Self Help Guide

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12
IBM WebSphere Portal V6 Self Help Guide
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
Web Services
Messaging
Adapters
Interface Coupling
Tight.
No. An application may
process a variety of
messages.
Tight.
Transport Coupling
Loose.
Tight.
Tight.
Implementation
Portability
Yes.
Yes.
No.
Security
Standards defined -
Not universally
implemented.
Vendor-specific.
EIS-specific.
Transaction Support
Standards defined -
Not universally
implemented.
Limited in scope to
queue entry point.
Yes.
Synchronous
Invocation
Yes.
Custom
implementation.
No.
Asynchronous
Invocation
Yes.
Yes.
EIS-specific.
Event Driven
Yes.
Yes.
EIS-specific.
Reliable Payload
Delivery
Standard Defined.
Yes.
EIS-specific -
Functionality provided
by actual adapters.