Release 10.1A: OpenEdge Development:
Java Open Clients

Java mechanisms for passing temp-tables and ProDataSets

In the Java Open Client, the default mechanism for passing either a single temp-table or a ProDataSet parameter (static or dynamic) is the OpenEdge ProDataGraph. The ProDataGraph class is an implementation of the DataGraph interface defined by Java Service Data Objects (Java SDO), a standard for managing complex data jointly developed by IBM and BEA. An alternative mechanism for passing temp-tables (but not ProDataSets) is the SQL ResultSet interface, supported by the Java Database Connectivity (JDBC) standard.

ProDataGraph mechanism

The ProDataGraph provides a cached and scrollable model for transferring complex data between the AppServer and the Java Open Client. This model allows you to access any row of any temp-table from beginning to end and in any direction. You can use the same model and programming techniques for accessing individual temp-tables or ProDataSets. It thereby provides a convenient model for passing and managing both types of complex data without having to repeatedly retrieve the data from the AppServer.

For more information on passing and managing a temp-table or ProDataSet as a ProDataGraph object, see Chapter 5, " Accessing Progress ProDataSets."

SQL ResultSets mechanism

The SQL ResultSet provides a data streaming model for accessing temp-tables only and is the only mechanism for accessing complex data in the Java Open Client prior to OpenEdge Release 10.1A. This model works similar to a one-way tape reader or writer. It allows you to access the records (rows) of a temp-table parameter in only one direction, from beginning to end. To access previous rows, you must re-start the retrieval from the beginning. It is provided mainly for backward compatibility.

For more information on passing and managing a temp-table as an SQL ResultSet, see Appendix C "Passing Temp-tables as SQL ResultSet Parameters."

Choosing the parameter passing mechanism

The ProDataGraph is the default mechanism for accessing temp-tables and ProDataSets. However, you can access temp-table parameters as an SQL ResultSet in a given method for the following conditions:

The Java Open Client proxies are generated from an Open Client interface defined in an OpenEdge release prior to Release 10.1A.
A given proxy method does not also pass a ProDataSet parameter (not available in releases prior to 10.1A).

Thus, ProxyGen provides an option for you to select the SQL ResultSet as the mechanism for passing temp-table parameters. You can specify this option for an entire AppObject/SubAppObject or for individual methods (procedures and user-defined functions). However, if a given method passes a ProDataSet, this option is unavailable and you must map any temp-table parameter to a ProDataGraph in that method.

Also to facilitate backward compatibility, in Open Client project files created prior to OpenEdge Release 10.1A, the SQL ResultSet option is selected by default.

For more information, see the ProxyGen help and OpenEdge Development: Open Client Introduction and Programming .