Patterns: Extended Enterprise SOA and Web Services

68 Patterns: Extended Enterprise SOA and Web Services

an appropriate Application pattern is your next step. If the Extended Enterprise

business pattern is not appropriate for your development efforts, review the

Business patterns again to determine which pattern best addresses your

e-business needs.

4.3 Extended Enterprise application patterns

We present the Extended Enterprise Application patterns in order of increasing

flexibility and sophistication. As the Application patterns build on each other, their

capabilities and reliance on middleware increase, and they require less

application development. Use the graph show in Figure 4-2 to select the

Application pattern that best fits your requirements.

Figure 4-2 The Extended Enterprise application patterns

Note: While the Exposed Parallel Process Application pattern is another

possibility, it is not currently being observed in the Extended Enterprise

domain. We expect the Exposed Parallel Process Application pattern to

appear at a later stage.

Exposed Direct Connection

Variations: Message/Call Connection

No

Yes

No Yes

Parallel Interaction

Serial Interaction

Source

Application

Target

Application

Exposed Broker

Variation: Exposed Router

Exposed Serial Process

Variation: Exposed Serial Workflow

Connection

Rules

Target

Application

Source

Application

Broker

Rules

Target

Application

Target

Application

Target

Application

Source

Application

Serial

Process

Rules

Tier

Target

Application

Target

Application

Chapter 4. Extended Enterprise pattern 69

Business and IT drivers

Table 4-3 and Table 4-4 on page 70 summarize the business and IT drivers for

the Extended Enterprise application patterns and their variations.

Table 4-3 Business drivers

Business drivers

Exposed Direct Connection

Message connection

Exposed Direct Connection

Call connection

Exposed Router variation

Exposed Broker

Exposed Serial Process

Exposed Serial Workflow

variation

Improve organizational efficiency 999999

Reduce the latency of business events 999999

Support a structured exchange with business partners 999999

Support real-time one-way message flows to partner

processes

99999

Support real-time request/reply message flows to partner

processes

99999

Support dynamic routing of message between partners to

one of many target applications

9999

Support dynamic distribution of message between partners

to multiple target applications

999

Support automated coordination of business process flow

between partners

99

Support human interaction and intervention within the

process flow between partners

9

70 Patterns: Extended Enterprise SOA and Web Services

Table 4-4 IT drivers

IT drivers

Exposed Direct Connection

Message connection

Exposed Direct Connection

Call connection

Exposed Router variation

Exposed Broker

Exposed Serial Process

Exposed Serial Workflow

variation

Minimize total cost of ownership (TCO) 9999

Leverage existing skills 999999

Leverage the existing investment 999999

Enable back-end application integration 999999

Minimize application complexity 999999

Minimize enterprise complexity 9999

Improve maintainability 9999

Improve flexibility by externalizing process logic from

application logic

99

Support long running transactions 9

Chapter 4. Extended Enterprise pattern 71

Legend for Extended Enterprise application patterns

The conventions shown in Figure 4-3 are used to describe the Extended

Enterprise application patterns in illustrations that follow.

Figure 4-3 Application pattern diagram conventions

4.3.1 Exposed Direct Connection application pattern

The Exposed Direct Connection application pattern represents the simplest

interaction type based on a one-to-one topology. It allows a pair of applications to

directly communicate with each other across organization boundaries.

Interactions between a source and a target application can be arbitrarily

complex. Generally, complexity can be addressed by breaking down interactions

into more elementary interactions.

More complex point-to-point connections have modeled connection rules, such

as business rules, associated with them, as shown in Figure 4-4 on page 72.

Connection Rules generally control the mode of operation of a connector,

depending on external factors. Examples of Connection Rules are:

򐂰 Business data mapping rules (for adapter connectors)

򐂰 Autonomic rules (such as priority in a shared environment)

򐂰 Security rules

򐂰 Capacity and availability rules

Transient data

Work in progress

Cached committed

data

Staged data

(data replication flow)

Application node containing

existing code with no need

for modification for this project

or that cannot be changed.

Read/write data

Read only data

Application node

containing new or modified

code for this project.

A set of applications whose

characteristics are unspecified.

Only the means with which

to interact with them is specified.

A small solid circle indicates the initiating node.

A single arrow indicates that a response is not needed.

Double arrows indicate that a response is needed.