Chapter 10. Exposed Direct Connection runtime pattern: generic profile 159
of business events and also requires the Manufacturer to respond in real-time
to the replenishment order placed by the Warehouse.
The Warehouse system also needs to have the flexibility to support the
heterogeneous and existing environments of their Manufacturing partner
systems. ITSO Good expects its IT systems to use interoperable standards
for its integration with external systems.
This scenario represents the organization’s first attempt to implement a
service-oriented architecture (SOA) solution. The systems that make up the
scenario are fixed and established. Their location and naming conventions
are not expected to change.
10.2 Design guidelines
Besides the usual guidelines that govern application integration design,
integration in an extended enterprise has some additional guidelines related to
the qualities of service, policies, and so forth.
In an intraenterprise application integration scenario, interactions are made
within an enterprise’s trusted networks. But in an extended enterprise, integration
with the partner's business processes might involve interactions that are exposed
to less secured zones such as the internet or shared Wide Area Networks
(WANs). As a result, qualities such as security, reliability, and interoperability
need special attention. These service qualities manifest themselves with differing
degrees of importance and specificity in different integration scenarios.
The design guidelines detailed here and in the following chapters are also
influenced by the trading partner agreements and service level agreements
between the organizations involved.
The design guidelines section is split into the following categories:
Analyze business requirements
Describes the system context of the problem this chapter is trying to solve.
Selecting a pattern
Describes which Extended Enterprise runtime pattern from the Patterns for
e-business is suitable to solve this business problem.
Analyze design options
Describes design decisions in building the solution.
160 Patterns: Extended Enterprise SOA and Web Services
Products
Lists the appropriate IBM products that can be used to implement the
solution, and provides a product mapping of the products used in the actual
implementation.
10.2.1 Analyze business requirements
Figure 10-2 shows the system context diagram depicting the interactions of ITSO
Good with external systems.
Figure 10-2 System context for the Exposed Direct Connection generic profile scenario
The Warehouse system is expected to integrate with three different types of
Manufacturer systems, implemented in Microsoft .NET, CICS Transaction Server,
and a WebSphere Application Server J2EE-based environment respectively. The
interactions are two-way (request/response) with the Manufacturer’s systems
responding to the submitted purchase order with an order confirmation.
10.2.2 Selecting a pattern
We use the Patterns for e-business to determine the appropriate Runtime pattern
to apply to this scenario. The Patterns approach is based on a set of layered
assets that can be exploited by any existing development methodology.
Figure 10-3 depicts these assets and their relationships to each other.
Manufacturer A
(WebSphere
Application Server)
Manufacturer B
(CICS Transaction
Server)
Manufacturer C
(Microsoft .NET)
Type: User Interactive
Protocol: HTTP
Placing Order
Track Order
Customer
Service
Representative
ITSO Good
Order Confirmation
Type: Interactive
Order Request
Order Request
Order Confirmation
Type: Interactive
Order Request
WebSphere
Application
Server
Order Confirmation
Type: Interactive
Chapter 10. Exposed Direct Connection runtime pattern: generic profile 161
Figure 10-3 The Patterns for e-business layered asset model
Here, we describe a step-by-step approach used to navigate the Patterns for
e-business asset catalog:
1. Business pattern
We select the Extended Enterprise business pattern since the given scenario
requires interactions between the business processes in the Warehouse and
Manufacturer systems that reside in separate enterprises.
2. Application pattern
The Warehouse and Manufacturer systems are required to interact on a
one-to-one basis representing point-to-point connections. Therefore we select
the Exposed Direct Connection application pattern. This pattern has two
variations:
– Message Connection variation
– Call Connection variation
Because the business scenario requires the proposed solution to support
real-time request/reply message flows to partner processes, we select the
Call Connection variation.
Best-Practice Guidelines
Application Design
Systems Management
Performance
Application Development
Technology Choices
Customer
requirements
Product
mappings
A
n
y
M
e
t
h
o
d
o
l
o
g
y
Runtime
patterns
Application
patterns
Composite
patterns
Business
patterns
Integration
patterns
162 Patterns: Extended Enterprise SOA and Web Services
3. Runtime pattern
The Application pattern provides us with the Direct Connection runtime
pattern for the proposed solution. Since this solution represents the first-step
in SOA transformation for ITSO Good, we select the generic profile of the
Direct Connection runtime pattern to keep the proposed solution simple.
Figure 10-4 shows the level 0 decomposition of the generic profile of the
Exposed Direct Connection runtime pattern, mapped onto the Exposed Direct
Connection application pattern.
Figure 10-4 Exposed Direct Connection::Runtime pattern = Generic profile
10.2.3 Analyze design options
Direct integration between applications can provide fast response time but at the
same time can be inflexible, in that any changes to one application can have
knock-on effects on other applications. This is especially dangerous when
integrating across organizational boundaries. Any changes to the exposed target
Inter-enterprise
Zone
Enterprise
Demilitarized Zone
Enterprise Secure Zone
Partner Zone
App Server/
Services
App Server/
Services
Network
Infrastructure
Protocol FirewallProtocol Firewall
Connector
App Server/
Services
App Server/
Services
Domain FirewallDomain Firewall
Exposed
Connector
Rules
Directory
App Server/
Services
Directory
& Security
Services
Target
Application
Connection
Rules
Source
Application
Exposed Direct Connection
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