7
Limitations

This chapter explains the limitations and workarounds when connecting to the J.D. Edwards OneWorld XE adapter. The following topics are discussed:

• Querying and Retrieving Lists of Records

Querying and Retrieving Lists of Records

The J.D. Edwards communication architecture is a single message, single reply architecture. You cannot return a list of messages or an array. The underlying code is C++, which calls with a pointer to a single structure, makes changes in the structure, and exits.

You cannot query and retrieve lists of records based on a search criteria using the J.D. Edwards OneWorld XE adapter due to a limitation with the J.D. Edwards business function architecture.

In J.D. Edwards, database connectivity is provided by using a set of proprietary (and complex) internal function calls. These calls mask the underlying database version by requiring very explicit and low-level calls to create lists of columns to retrieve or update, and create specialized structures for sorting or selection. The sets of APIs are not exposed through the Java (or any other) connectivity method, therefore, recordsets cannot be handled through business functions.

The J.D. Edwards database access APIs are not usable through the Java connector, therefore, managing lists of items (such as customers) can be challenging. It is relatively easy to create business functions in J.D. Edwards that handle a single record, or operate on a group of records, provided that all of the work is performed within the bounds of the J.D. Edwards toolset, but accessing lists of items outside the J.D. Edwards tools is more difficult.

To workaround this limitation you can create a custom business function in J.D. Edwards that returns a list of record keys based on a query. You must segment the lists because JDENET (J.D. Edwards' internal proprietary messaging API) has a limitation on the message buffer size for managing large or effectively unbounded result sets. The client code must iterate (loop) through successive calls to the business function, until an indicator is returned stating that the list is complete.

Controlling Iteration

All calls to J.D. Edwards business functions are stateless; therefore, the business function cannot maintain an open cursor and return more rows on request. Positioning information must be passed to the J.D. Edwards business function on each call.

The following is a list of techniques for controlling iteration:

• On the J.D. Edwards side, write the result set to a temporary storage area, such as a file, which returns an ID (such as a file name, or job number) that can be given on successive calls, along with the record number to position the cursor. Successive calls position within the list are based on the passed-in record number.

  Note: Calls through the J.D. Edwards OneWorld XE adapter can be load-balanced, however, they are eventually served by a single application server based on the credentials and business function being called. Therefore, if a temporary file was created on a server by one call, additional calls are served by the same server. For more information refer to Object Configuration Mapping in the JDE CNC Guides

• Position information (such as a primary key value) that can be passed back on the second and subsequent calls, and reissue the query based on the key as an additional parameter.

  Note: Of the first two techniques, the preferred method is to use primary key values and reissue the query. It requires the smallest amount of code, and places the optimization and caching burden on the database.

• A list of primary keys (such as a cross reference) can be stored by the calling application. For example, if a customer record is created by a Customer Relationship Management (CRM) system, then added to J.D. Edwards using a business function call, the business function that adds a customer record sets the value for the AN8 field (short address number) and is visible in the return buffer. This number can then be written to a reference field on the original customer record, or stored into a custom cross-reference table.

• Most master records in J.D. Edwards have a concept of a lookup, or alternate key. This key can be used to store the key information from the calling system and business functions exist, or can be created to perform the lookup on the J.D. Edwards side. When parameters are passed to the business function to create a customer record, the long key value is set.

  See Also: Interoperability topic in the J.D. Edwards help system