WebSphere Business Integration Adapters: An Adapter Development and WebSphere Business Integration Solution

Chapter 6. Business object handlers 75

However, such a recursive call assumes that the child business object is set as

follows:

 If the verb on a child business object is set, the method should perform the

specified operation.

 If the verb on the child business object is not set, the verb method should set

the verb in the child business object to the verb in the top-level business

object before calling another method on the child.

If an attribute has multiple cardinality (cardinality n), the attribute contains an

array of child business objects. In this case, the connector must access the

contents of the array before it can process individual child business objects.

From the array, the doVerbFor() method can access individual business objects:

 To access individual business objects, the method can get the number of

child business objects in the array with the getObjectCount() method and

then iterate through the objects.

 To get an individual child business object, the method can obtain the

business object at one element of the array.

After the doVerbFor() method has access to a child business object, it can

process the child recursively as needed.

6.8 Custom business object handlers

The Adapter Framework calls the doVerbFor() method in the

CWConnectorBOHandler class (which implements the business object handler)

for all verbs that a particular business object supports. Therefore, all verbs in a

business object are processed in one standard way (although they can initiate

different actions within the application). However, if your connector supports a

business object that requires different processing for some particular verb, you

can create a custom business object handler to handle that verb for the business

object.

Note: A connector should never create arrays for child business objects. An

array is always associated with a business object definition when cardinality is

n.

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6.8.1 Creating the class for the custom business object handler

To create a custom business object handler, you must create a class that

implements the CWCustomBOHandler interface. The CWCustomBOHandler

interface provides the doVerbForCustom() method, which you must implement to

define a custom business object handler. To create a custom business object

handler class for a Java connector:

1. Create a class that implements the CWCustomBOHandler interface.

2. Implement the doVerbForCustom() method to define the behavior of the

business object handler.

6.8.2 Implementing the doVerbForCustom() method

The doVerbForCustom() method provides the functionality for the custom

business object handler. The Adapter Framework calls the low-level doVerbFor()

method (defined in the BOHandlerBase class) for the appropriate business

object handler when it receives a request business object. This low-level

doVerbFor() method determines which business object handler to call as follows:

 If the business object’s verb has the CBOH tag in its application-specific

information, it calls the doVerbForCustom() method.

The CBOH tag specifies the full name (including the package name) of the

custom business object handler class, which implements the

CWCustomBOHandlerInterface interface and its doVerbForCustom() method.

If the CBOH tag exists, the low-level doVerbFor() method tries to create a new

instance of the class that this tag specifies. If this instantiation is successful,

the low-level doVerbFor() method calls the doVerbForCustom() method in this

class.

 Otherwise, it calls the doVerbFor() method, which the connector developer

must implement as part of the business object handler’s

CWConnectorBOHandler class.

The implementation of the doVerbForCustom() method must handle the verb

processing of the verb for which its class is specified. In this method, you must

customize the behavior of the doVerbForCustom() method to meet the special

processing needs of your business object’s verb.

Note: Unlike the doVerbFor() method, the doVerbForCustom() method is not

invoked directly by the Adapter Framework. Instead, the Adapter Framework

invokes the low-level doVerbFor() method, which in turn, invokes the

doVerbForCustom() method. Therefore, the doVerbForCustom() method

cannot include calls to any methods in the CWConnectorBOHandler class.

Chapter 6. Business object handlers 77

78 WebSphere Business Integration Adapters