10.4 Definition of the Model Problem


To start the model problem, we created a two-part hypothesis that establishes the design question.

  • Hypothesis part 1: The Micro Focus Net Express IDE can be used to support mixed-language programming with Java.

  • Hypothesis part 2 : The Java subroutines, invoked from Micro Focus COBOL, can interface with an EJB server and perform transactions with an Oracle 8i database.

If the first part cannot be supported, the second part is irrelevant.

After defining the design question, we identified the starting evaluation criteria that will determine whether the hypothesis can be supported.

  • Criterion 1: Committed updates from both the COBOL process and EJBs are applied correctly to the database.

  • Criterion 2: A rollback operation preserves the state of the database before the start of the transaction.

The final step in defining the model problem is identifying any implementation constraints on the model solution. These constraints are set by the design context and are an important part of the model-problem definition. In this case, both criteria can be trivially satisfied unless further constraints are specified.

  • The transaction must be started from the Micro Focus COBOL program and use the Java Transaction Service (JTS).

  • The Micro Focus COBOL program and the EJBs must write to the Oracle 8i database as part of the same transaction.

  • The Micro Focus COBOL program must write to the Oracle 8i database, using JDBC and SQL.

Taken together, the design question, starting evaluation criteria, and constraints define the model problem. In the next step, the engineer must produce a model solution situated in this design context.



Modernizing Legacy Systems
Modernizing Legacy Systems: Software Technologies, Engineering Processes, and Business Practices
ISBN: 0321118847
EAN: 2147483647
Year: 2003
Pages: 142

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