Overview
Testing and implementing changes to CICS (Customer Information Control System) programs or configurations is a critical process in mainframe environments. It ensures that updates do not disrupt existing services and that new features or fixes enhance the system's performance and reliability. This process involves careful planning, execution, and verification to mitigate risks associated with changes.
Key Concepts
- CICS Testing Types: Unit, integration, system, and acceptance testing.
- Change Management: Procedures and tools for managing code and configuration changes.
- Debugging and Troubleshooting: Techniques to identify and resolve issues in CICS environments.
Common Interview Questions
Basic Level
- How do you perform unit testing on CICS programs?
- What is the role of CICS supplied transactions like CEDF in testing?
Intermediate Level
- How do you manage version control and deployment of changes in CICS environments?
Advanced Level
- Discuss how to optimize CICS application performance during the development phase.
Detailed Answers
1. How do you perform unit testing on CICS programs?
Answer: Unit testing in CICS involves isolating a piece of code (typically a program or transaction) and verifying its correctness independently of other components. This can be achieved through manual testing or automated testing tools. For manual testing, developers can use CICS-supplied transactions such as CEDF (CICS Execute Diagnostic Facility) to step through the program and inspect variables and control flow. Automated testing might involve writing custom test drivers or using enterprise testing tools that simulate CICS transactions and assert expected outcomes.
Key Points:
- Isolate the program or transaction to be tested.
- Use CICS-supplied transactions for manual testing.
- Consider automated testing tools for more extensive testing.
Example:
// Example of a simple CICS program logic to be unit tested
public class CicsProgram
{
public int Add(int a, int b)
{
return a + b; // Simple addition method to demonstrate unit testing
}
}
// A hypothetical unit test case (assuming a C#-like syntax for illustration)
public void TestAddMethod()
{
CicsProgram program = new CicsProgram();
int result = program.Add(5, 3);
if(result == 8)
{
Console.WriteLine("Test passed");
}
else
{
Console.WriteLine("Test failed");
}
}
Note: Actual CICS programs are not written in C#; this is a simplified example to illustrate the concept.
2. What is the role of CICS supplied transactions like CEDF in testing?
Answer: CICS supplies various transactions that aid in testing and debugging. CEDF (CICS Execute Diagnostic Facility) is particularly useful as it allows a developer to execute a program interactively, displaying each EXEC CICS command before and after execution. This facilitates a detailed inspection of the program's behavior, including the examination of variables, the control flow, and the identification of errors or unexpected behavior. It's an essential tool for understanding how a program interacts with the CICS environment and for troubleshooting issues.
Key Points:
- CEDF allows for interactive execution and debugging.
- It helps in inspecting variables and control flow.
- CEDF is crucial for troubleshooting and understanding program behavior.
Example:
// No direct C# example for CEDF, as it is a CICS-specific transaction.
// Description of using CEDF:
1. Start CEDF and specify the transaction ID you wish to debug.
2. Execute the transaction. CEDF intercepts each EXEC CICS command.
3. Inspect or modify data as needed before proceeding to the next command.
4. Continue until the transaction completes, observing the program's behavior.
3. How do you manage version control and deployment of changes in CICS environments?
Answer: Managing version control and deployment in CICS involves utilizing SCM (Source Code Management) tools compatible with mainframe environments, such as Git, Endevor, or ChangeMan. These tools help track changes, maintain multiple versions of code, and facilitate collaborative development. Deployment of changes typically follows a rigorous testing process, including unit, integration, system, and acceptance tests, before changes are moved to production through automated deployment pipelines or manual processes, ensuring compliance with organizational change management policies.
Key Points:
- Use SCM tools compatible with mainframe environments.
- Follow a rigorous testing process before deployment.
- Compliance with organizational change management policies is crucial.
Example:
// Example illustrating version control concepts in a CICS context
// Note: Actual version control commands are not applicable in a C# example.
1. Check out the CICS program source code from the version control repository.
2. Make necessary changes for the new feature or bug fix.
3. Perform unit and integration tests in a development or test CICS region.
4. Commit the changes with a meaningful message describing the update.
5. Collaborate with the team for code review and further testing.
6. Deploy the changes to production following the organization's deployment process.
4. Discuss how to optimize CICS application performance during the development phase.
Answer: Optimizing CICS application performance involves several strategies starting from the development phase. This includes efficient use of CICS resources, such as minimizing the use of temporary storage (TS) queues and ensuring effective use of COMMAREA for passing data between programs. Developers should also focus on optimizing DB2 SQL queries used within CICS transactions for better performance. Employing tools for performance analysis and testing, such as IBM's CICS Performance Analyzer, helps in identifying bottlenecks and areas for improvement early in the development cycle.
Key Points:
- Efficient use of CICS resources and minimizing temporary storage usage.
- Optimizing DB2 SQL queries for performance.
- Using performance analysis tools to identify and address bottlenecks early.
Example:
// Example highlighting optimization in a hypothetical SQL query within a CICS program
// Note: Actual SQL optimization techniques apply, not specific C# code.
// Before optimization: Inefficient SQL query
SELECT * FROM orders WHERE order_date = CURRENT DATE
// After optimization: Efficient SQL query with indexed column
SELECT order_id, customer_id, order_amount FROM orders WHERE order_date = CURRENT DATE AND status = 'ACTIVE'
// Key optimization points:
1. Select only required columns instead of '*'.
2. Use of an indexed column in the WHERE clause to enhance retrieval speed.
Note: The examples provided are illustrative of the concepts and not direct CICS or C# code implementations.
