Configuring data handlers

Data-handler meta-objects allow a connector or Server Access Interface process to instantiate a data handler based on the MIME type of an input file or the MIME type specified in a business object request. To configure a data handler, you must ensure that its meta-objects are correctly initialized and available to the calling components (a connector or an access client).

Note:
Each IBM-delivered data handler uses configuration properties that are defined in data-handler meta-objects.

In support of the IBM-delivered data handlers, IBM delivers the data-handler meta-objects listed in Table 7.

Table 7. IBM-delivered data-handler meta-objects
Meta-object level Quantity Location
Top-Level


For InterChange Server Express One repository\edk

For connector One DataHandlers\repository\ DataHandlers
Child One for each data handler DataHandlers\repository\ DataHandlers

To configure the use of one or more data handlers for use by a caller, you must:

Top-level meta-objects

A top-level data-handler meta-object associates a MIME type with a child data-handler meta-object. The child meta-object provides configuration information, which always includes the name of the data handler class to instantiate. Therefore, a top-level meta-object associates a MIME type with a data handler. All calling components with access to a particular top-level meta-object can invoke any of the data handlers whose MIME type appears in this meta-object.

You can control which data handlers a calling component can support by grouping the appropriate MIME-type attributes in a particular top-level meta-object and having the calling component provide the name of the meta-object that contains the data handlers it needs to use. IBM delivers the following top-level data-handler meta-objects:

MO_Server_DataHandler meta-object

The Server Access Interface process uses the MO_Server_DataHandler meta-object to identify the data handlers it can use. The delivered version of MO_Server_DataHandler is not configured to support any MIME types. It includes only a single dummy attribute. You can customize this meta-object to support any data handler installed with your InterChange Server Express. If you want your access clients to support a MIME type, rename the dummy attribute in the top-level MO_Server_DataHandler meta-object to the name of the supported MIME type and provide the associated child meta-object for that MIME type.

For example, to provide access clients with support for the text_xml MIME type, rename the dummy attribute to text_xml and provide the name of the MIME type's associated child meta-object as the attribute's type. This child meta-object configures the XML data handler. Figure 9 illustrates a MO_Server_DataHandler meta-object that contains one attribute, text_xml, which represents the MO_DataHandler_DefaultXMLConfig child meta-object.

Figure 9. MO_Server_DataHandler meta-object


If you want your access clients to support additional MIME types, define a new attribute in the top-level MO_Server_DataHandler meta-object for each MIME type and provide the associated child meta-object for that MIME type. If you are invoking more than one data handler, you must define a child meta-object for each data handler instance. To provide support for an additional MIME type, you can either:

Note:
The name of the top-level server meta-object for data handlers must be the default name of MO_Server_DataHandler, but you can configure the top-level meta-object to contain any number of child meta-objects.

MO_DataHandler_Default meta-object

By default, a connector uses the MO_DataHandler_Default meta-object to identify the data handlers it can use. The delivered version of MO_DataHandler_Default is configured to support the MIME types of all IBM-delivered data handlers (including some adapter-specific data handlers that are not covered in this document).

If you want your connector to support different MIME types, you must ensure that an attribute exists in the MO_DataHandler_Default meta-object for each MIME type that you want the connector to support. This attribute must specify the appropriate MIME type and represent the associated child meta-object for that MIME type. To provide support for an additional MIME type, you can define your own custom MIME type and child meta-object, as long as you have a data handler that supports it.

Note:
You can change the name of the top-level meta-object for connectors to correspond to a particular connector, or even a particular business object or a particular type of file that the connector needs to process. Whatever object you use, however, must be supported by the connector definition, so if you use a different top-level object you must configure the connector definition to support it. For more information, see Configuring a connector to use data handlers.

Figure 10 shows a top-level data-handler meta-object for connectors that defines two data handlers: XML and NameValue.

Figure 10. Example meta-object for two different data handlers


Note:
For a connector to be able to access a data handler, the top-level data-handler meta-object must be on the list of supported objects for the connector. Otherwise, the connector cannot load the meta-object at startup.

Child meta-objects

A child data-handler meta-object is a flat business object that contains configuration information to initialize a data handler. Different types of data handlers have different configuration requirements, so child meta-objects have different attributes. This configuration information customizes the behavior of the data handler instance. Therefore, a set of attribute values in a child meta-object defines a specific configuration, which in turn is associated with a particular data handler behavior. All callers that access a particular child meta-object invoke the behavior of the associated data handler that the configuration information defines.

IBM delivers a child data-handler meta-object for each of the data handlers it delivers, as Table 8 shows .

Table 8. Child data-handler meta-objects
Child meta-object For more information
MO_DataHandler_DefaultXMLConfig Configuring the XML data handler
MO_DataHandler_DefaultEDIConfig Configuring the EDI data handler
MO_DataHandler_DefaultFixedWidthConfig Configuring the FixedWidth data handler
MO_DataHandler_DefaultDelimitedConfig Configuring the Delimited data handler
MO_DataHandler_DefaultNameValueConfig Configuring the NameValue data handler
MO_DataHandler_DefaultRequestResponseConfig Configuring the Request-Response data handler

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