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Unit 6: Source Integration

Service-based application integration is not a new approach. We’ve been looking for mechanisms notes
to bind applications together at the service level for years, including frameworks, transactions,
and distributed objects all in wide use today. However, the new notion of Web services, such as
Microsoft’s .NET strategy, is picking up steam as we attempt to identify a new mechanism that’s
better able to leverage the power of the Internet to provide access to remote application services
through a well-defined interface and directory service: Universal Description, Discovery and
Integration (UDDI).
The uses for this type of integration are endless, including the creation of composite applications,
or applications that aggregate the processes and information of many applications. For example,
using this paradigm, application developers simply need to create the interface and add the
application services by binding the interface to as many Internet-connected application services
as are required.
The downside, at least with service-based integration, is that this makes it necessary to change
the source and target applications or, worse in a number of instances, to create a new application
(a composite application). This has the effect of adding cost to the application integration project
and is the reason many choose to stay at the information level.
Still, the upside of this approach is that it is consistent with the “baby step” approach most
enterprises find comfortable when implementing solutions to integration problems. Service-based
solutions tend to be created in a series of small, lower-risk steps. This type of implementation can
be successful from the department to the enterprise to the trading community, but never the
other way around from the trading community to the department.

6.6 the practice of source integration

service-oriented application integration

Service-oriented integration (SOI) is defined as integrating computing entities using only service
interactions in a service-oriented architecture. Service-oriented integration addresses problems
with integrating legacy and inflexible heterogeneous systems by enabling IT organizations to
offer the functionality locked in existing applications as reusable services.
In contrast to traditional enterprise application integration (EAI), the significant characteristics of
services-oriented integration are:
1. Well-defined, standardized interfaces: Consumers are provided with easily understood
and consistent access to the underlying service.

2. Opaqueness: The technology and location of the application providing the functionality is
hidden behind the service interface. In fact, there is no need for a fixed services provider.
3. Flexibility: Both the providers of services and consumers of services can change - the
service description is the only constant. Provided both the provider and consumer continue
to adhere to the service description, the applications will continue to work.
Service-oriented Application Integration (SOAI) allows applications to share common business
logic or methods. This is accomplished either by defining methods that can be shared, and
therefore integrated, or by providing the infrastructure for such method sharing such as Web
services (Figure 6.1). Methods may be shared either by being hosted on a central server, by
accessing them interapplication (e.g., distributed objects), or through standard Web services
mechanisms, such as .NET.

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