Chapter 8. Integration using WebSphere Business Integration Adapters 201
???? Bi-directional
The adapters have the ability to both send information to the EIS and to
retrieve events from the EIS. The process of sending information to the EIS is
referred to as
request processing. Processing a request from an integration
broker or a client service to perform an operation in the EIS.
Event
notification
is the retrieval of changes and updates in an EIS component and
propagating these changes to an integration broker or client service.
???? Multi-threaded request processing
Typically, an adapter is multi-threaded during request processing. Thus, the
adapter can handle multiple simultaneous requests to perform different
operations on the EIS, allowing for scalability and better performance.
There are two distinct type of adapters:
???? Application adapters
???? Technology adapters
These two types of adapters allow integration with legacy applications,
mainframe systems, and different technologies. The application adapters provide
for integration through the use of the EIS-specific API. These EIS include SAP,
PeopleSoft, i2, JD Edwards, Siebel, and Oracle Applications. The technology
adapters provide integration using standard technologies such as JDBC, JMS,
and Web services. The technology adapters include JDBC for relational
database, JText for text files, and Web services for service integration to
WebSphere Business Integration.
For a complete listing of available adapters, see:
http://www.ibm.com/software/integration/wbiadapters
The adapters typically include an object discovery component that allows for
metadata introspection and business object creation. Metadata introspection is
the process of retrieving information about the data, program objects, or
processes in an EIS.
8.2 Adapter-based integration
Integration using WebSphere Business Integration Adapters can be
accomplished by using an integration broker or a client service to initiate
requests or to accept events from the adapter. Through the use of the adapter
framework, the broker or client can integrate with different enterprise applications
using multiple WebSphere Business Integration Adapters.
202 Managing Information Access to an EIS Using J2EE and Services Oriented Architecture
Business objects are developed, and the adapter is configured to connect to a
specific instance of the EIS. The adapter is then deployed, and its service and
operations are exposed within an integration broker or client, which then makes
calls on the underlying EIS.
8.2.1 Adapter request processing interaction pattern
With request processing, the integration broker and clients send requests that
use a business object to the adapter through the adapter framework. The
adapter parses the incoming business object and makes the request specified on
the EIS using application-specific metadata and the business object content. The
adapter then returns the results, if any, of the call. WebSphere Business
Integration Adapters typically perform create, update, delete, and retrieve
functions using the verb attribute within a business object. Adapters can also
execute business processes in an underlying EIS (for example, to calculate an
order schedule).
Within the interaction pattern for request processing within WebSphere Business
Integration Server Foundation, the BPEL process makes a request through JMS
on the adapter. Figure 8-1 shows the components view for this interaction style.
Figure 8-1 Request interaction pattern components view
The adapter can process requests from a business process in two ways:
???? The BPEL process can send a synchronous request to the adapter, where the
process sends a request to the adapter and waits for a response. This
process is also referred to as the
Hub Request interaction pattern, where the
hub in this case is the executing business process. The names of the port
types in the adapter service WSDL files reflect this pattern in their naming
convention.
???? The BPEL process can also invoke an asynchronous request on the adapter,
where the process sends a request to the adapter without waiting for a
response. This process is referred to as the
Hub One Way interaction pattern.
The WebSphere Business Integration Adapter is created as a WebSphere
Application Server project within the WebSphere Business Integration tool set
and is configured to access the EIS with the appropriate business objects. The
WebSphere Business Integration
Server Foundation
JMS
WBI Adapter
Adapter Framework
M
Q
EIS
BPEL
Process
Chapter 8. Integration using WebSphere Business Integration Adapters 203
project is then exported with a JMS binding service, which exposes the
operations and business objects available for the adapter. The adapter service is
then incorporated into a BPEL process, which makes WSIF calls to the adapter
through the configured WebSphere MQ queue connection factory and queues.
The adapter retrieves the request, processes the business object by parsing and
analyzing application specific metadata, then executes the operation on the
underlying EIS. The result is then parsed and transformed into a business object
and sent to the business process.
8.2.2 Adapter event notification interaction pattern
With event notification, the adapter sends a messages to the integration broker
or client, signifying that a data change or process activity has happened in the
EIS.
There are several different mechanisms for event propagation from an EIS to the
integration broker. The mechanism relies on the capabilities of the EIS.
Mechanisms for event propagation include a registering for events, a service
callback system, polling an event data store, and using triggering scripts.
Most EIS vendors do not provide any event notification mechanism. The
WebSphere Business Integration Adapters need to develop or include an
appropriate notifying device to capture and express these events.
Adapters typically use an event store located within the EIS. This event store is
populated using a triggering mechanism that is specific to the EIS component.
The events are then retrieved from the event store and propagated to the
integration broker or client.
The interaction pattern for event notification within WebSphere Business
Integration Server Foundation involves the adapter invoking a BPEL service after
an event has happened in the EIS. Figure 8-2 on page 204 shows the
components involved in an event notification interaction.
204 Managing Information Access to an EIS Using J2EE and Services Oriented Architecture
Figure 8-2 Event notification Interaction components view
The adapter can send event notifications in two ways to the business process.
???? The adapter can send a synchronous event delivery, where the adapter sends
a message to the processes and expects a response. This process is also
referred to as the
Agent Request interaction pattern. The names of the port
types in the adapter service WSDL files reflect this pattern naming
convention.
???? The adapter can also do an asynchronous event delivery, where the adapter
sends a message to the business process and does not wait for a response.
This process is referred to as the
Agent Delivery interaction pattern.
In both scenarios an MDB is used to listen for events on the queue configured for
event delivery. The adapter polls for events in the EIS then retrieves the events
and places them on the appropriate delivery queue. The event messages are
retrieved from the queues and sent to the business process.
8.2.3 Adapter object discovery
The adapters object discovery agent (ODA) introspects metadata information
from the EIS by either analyzing the application’s data store, business
processes, and components or by using a metadata introspection API.
The adapter ODA is written using the object discovery agent development kit
(ODK). It provides a set of APIs that allows for tight integration with the
WebSphere Business Integration Business Object Designer Tool. The ODK also
provides guidance to developers on how to develop an ODA.
The ODA generally creates ready-to-use business objects, with
application-specific metadata already in place. There is little to no customization
required on the developers part at design time.
WebSphere Business Integration
Server Foundation
BPEL
Process
Calls
Listens
WBI Adapter
Adapter Framework
M
Q
Message Driven Bean
EIS
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