34 Managing Information Access to an EIS Using J2EE and Services Oriented Architecture
Table 2-8 SOA with components
Components with SOA
The true potential of components and SOA only really comes when you have
both of them. With both, you have:
???? Components and services assembled with loose coupling and dynamic
recoupling.
???? Coherent service interfaces supported by flexible component-based
application.
???? Service-based approach applies both inside and outside the application.
???? Scalable, flexible, on demand solutions.
2.2.4 Meta-architecture
The meta-architecture is a set of high-level decisions that strongly influenced the
integrity and structure of the EIS system process and EIS component, but is not
itself the structure of the overall back-end integration solution. The
meta-architecture, through style, patterns of composition, principles, and
philosophy, rules out certain structural choices, and guides selection decisions
and trade-offs among others.
Principles
The purpose of this meta-architecture is not to define the principles of a service
orientation architecture style but rather to focus on the principles of the EIS
process and component.
Potential benefits Potential drawbacks
Services developed rapidly from existing
applications and packages.
Inflexibility behind service interface.
Opportunities for reuse and economics of
scale.
Existing applications and packages
preserve their legacy limitations.
Useful path towards further
re-engineering.
Concerns about scalability and portability
of implementation.
Re-engineering may never happen.
Chapter 2. Architecture 35
Key principles for the EIS integration process and component are:
???? Stability through interfaces
– EIS system process and EIS component exposed as services, using a
services-based architecture style
– A service is a window into a business process
???? Optimize for the enterprise
– Enterprise services
– Enterprise processes
– Enterprise components
???? Utilize standard technologies
– Services, processes and components must adhere to standards and
specifications
???? Component base architecture
???? Use a framework
– The same approach as the Template Method design pattern, but applied
on a much larger scale. Frameworks are concrete, not abstract.
Platform of composition
The architecture is composed of logical layers and physical tiers. Figure 2-2 on
page 17 shows a graphical view of the conceptual architecture layers from an
enterprise perspective. The EIS system process and EIS component is
implemented in the process and component layers, respectively. Table 2-1 on
page 14 gives a description of the logical layers that our layered architecture
uses.
Vision
The EIS service, process, and component should deliver on the SOA goals of
business agility, on demand computing, loosely coupled components, processes,
and services.
Note: OO design is more important than any particular implementation
technology (such as J2EE or even Java). Good programming practices and
sound OO design underpin good J2EE applications. Bad Java code is bad
J2EE code. For more information, see Expert One-on-One J2EE Design and
Development, Rod Johnson, ISBN: 0-7645-4385-7, also available at:
http://www.wrox.com/WileyCDA/WroxTitle/productCd-0764543857.html
36 Managing Information Access to an EIS Using J2EE and Services Oriented Architecture
Any new business use case, and indeed even new business requirements added
to an existing use case, would probably require integrating with a new or existing
back-end transaction or changing an existing transaction.
Looking at the development life cycle, and more specifically, at how we have
been creating modular programs, designers and developers (who have different
skills and experience and backgrounds) are always faced with the challenge of
calling a back-end transaction. The reality is that back-end system integration is
difficult to implement and to maintain.
By creating an EIS system service and process that uses an EIS component, the
vision is that channel applications and enterprise business process designers
and developers can focus on doing what they do well — implementing their
business unit’s business processes, creating application presentations, and
realizing their business use cases, without worrying about how to integrate with a
back-end system.
Concepts
Some of the main concepts in the EIS architecture are:
???? Declarative programming model
– Defining new J2C connectors
– Feature classes being used in context to business processes are
declaratively configured
– Context-based EIS integration styles
– Versioning of feature classes and EIS components
???? Business process management
– Graphical process modeling
– Process engine processing business, system. and utility processes
– Business Process Choreographer
– Enterprise business, system, and utility processes, exposed as services,
using a service-based architecture style
???? Composite applications and processes
– Component-based development, rather than modular programming
???? Services-based architecture style
– Interoperability
– A service is a window into a business process
Chapter 2. Architecture 37
2.2.5 Conceptual architecture
The conceptual architecture is an abstract view of the EIS integration
architecture. In this section, we illustrate and discuss the conceptual architecture
using structural and behavioral views.
Structural view
Figure 2-8 illustrates a structural view of the conceptual EIS integration
architecture.
Figure 2-8 EIS integration conceptual architecture structural view
Business processes
Business processes would typically be enterprise business processes (also
sometimes referred to as critical business processes) that are used by channel
applications, or other business processes that use a services based architecture.
(See Table 2-1 on page 14 for a discussion on the logical architectural layers.)
Conceptually, business processes do not have to execute on a different physical
tier from a channel application. The vision, however, is that enterprise business
processes must be used by all channel applications across an enterprise that
uses a services-based architecture style. For information about the concept of
business process management, see “Concepts” on page 36.
Local EIS
EIS
EIS
Remote EIS
EIS
EIS
Business Processes
System Process (EIS)
Transaction Management
Security
38 Managing Information Access to an EIS Using J2EE and Services Oriented Architecture
System processes
The EIS system process represents the EIS integration level 3 discussed in
“Level 3, application to EIS system process” on page 16. The EIS system
process must includes activities such as:
???? Configuration
Using context information of a calling business process, it can reference a
configuration source for information that must be passed to the EIS
component. Some of the configuration data can be:
– Local or remote EIS component
See “Local versus remote EIS components” on page 39 for a discussion
about local and a remote EIS components.
– EIS integration style
Indicates to the EIS component which J2C connector or JDBC
DataSource it must use to connect to a back-end system or database.
– EIS feature class name
The name of the feature class that is used by the EIS integration
components. See “EIS integration feature classes” on page 40 for a
description about an EIS feature class.
???? Data mapping
Mapping of the EIS system process variable(s) to the EIS component
variable(s).
???? Invoke EIS component
– Local EIS component
– Remote EIS component
???? Exception handling and reporting
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