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Chapter 5: Analyzing Data Impacts

In this session, you look at Revolve's impact analysis capabilities. First you assess an impact manually, then you trace further impacts using the automatic impact analysis feature.

Please see the Tutorials Map to check that you have run all necessary previous sessions.

5.1 Overview

When you edit source code your changes might impact other components besides the ones you edited. You use the Impact Analysis tool to identify where these impacts are so you can fix them before they create difficulties.

In this session, you first use the Browsers menu to find an item of interest. You then use the code navigation facilities of Revolve to manually follow logical connections defined in the source code to analyze impacts, or have Revolve automatically determine the impact of changing the item. A step-by-step example of both Manual Impact Tracing and Automatic Impact Tracing are provided in this session.

5.2 Preparation

This session uses the project you created in the chapter Using Revolve.

  1. If you have closed Revolve, open it as before.

  2. Open the Sample project by selecting it from the "recently used files" list at the bottom of the Project menu.

5.3 Tracing Impacts Manually

To trace impacts manually:

  1. Select Browsers > Literals.

  2. Type the character A in the Literals Match edit box. Click Match or press Enter.

    This searches the source code for the literal "a". The search result is displayed in the window, and the edit bar indicates that one match has been found.

  3. Select the A folder by clicking it.

  4. Click Expand Completely.

  5. Select Line 267: under ONLINE6.CBL.

  6. Click View Source Code.

    This button toggles the Split Screen Editor on and off. The window is horizontally split and the source code for the selected item is selected in the bottom window. You can edit source code here if you wish.

  7. Hit the down arrow key four times.

    Notice that each time the selection in the top window changes, the corresponding source code is displayed in the Split Screen Editor.

  8. Hit the up arrow key four times.

    The A on the line that begins IF ONL0006-ACTION-LOAD-I = ("A"... is selected in the Split Screen Editor.

    In this way, you can quickly get to all the places in the application that use the constant A. These locations can be used as starting points for impact analysis.

  9. Click on the ONL0006-ACTION-LOAD-I variable in the IF statement in the Split Screen Editor. See Figure 5-1.

    Figure 5-1: Selecting in the Split Screen Editor

  10. Click Definition of Usage.

    This scrolls the Split Screen Editor to the working-storage definition of the selected item.

  11. Click Backup one logical level.

    The group item ONL0006I is selected.

  12. Click Next Usage twice to scroll to the location where ONL0006I is used in a CICS INTO clause.

  13. Click Backup one logical level twice to see that the INTO clause is part of a RECEIVE MAP statement.

    The code navigation features of the Split Screen Editor enable you to quickly examine the source code and find where the value of ONL0006-ACTION-LOAD-I is set. This is critical information because this data item was found through its relationship to the literal A, which was the start of our analysis. Should changes be made to A, ONL0006-ACTION-LOAD-I will be affected.

  14. Click Execution Simulator.

    The Execution Simulator toolbar appears in the window. Using this, you can simulate execution of the code either forward or backward so that the logical paths through the source code can be traced to determine impacts.

  15. Click the Run button .

    Since the statement being executed is a CICS RECEIVE, the appropriate Screen view is displayed. Also the Execution Condition dialog is displayed to affirm the conditional statement.

    Since the literal A was an action code, it is not surprising that the screen has an "ACTION:" heading followed by a one-byte entry field. In fact, this is the field that is impacted by the literal that you used to begin this analysis.

  16. Press Cancel in the Execution Simulator Branch Choicesdialog.

  17. Click Window > Close All Windows.

5.4 Tracing Impacts Automatically

A faster, more accurate approach is to have Revolve automatically determine the areas impacted by changing an item. This session illustrates Automatic Impact Tracing by determining the impact of changing the variable TREND-KEY which is used to access the VSAM file PROD.TREND.MASTER.

  1. Click Browsers > Data Files.

    The Data Files browser is displayed.

  2. Type *trend* in the Match edit box and click Match or press Enter.

    The folder PROD.TREND.MASTER is displayed in the information window.

  3. Select PROD.TREND.MASTER and click Expand Completely.

    The folder is expanded and all the source files that reference the data file are displayed.

  4. Select the line under ONLINE7.CBL that reads:
    Line 100: cics_state_read
  5. Click View Source Code.

    The source code appears in the Split Screen Editor.

    The selection is positioned to a CICS READ of the dataset TRENDMS. This CICS dataset is an alias for the dataset PROD.TREND.MASTER. The alias is established in the ONLINE.FCT file that is also displayed in the information window.

  6. Right-click the data item TREND-KEY in the RIDFLD option of the selected CICS READ section, then on the popup menu click Tools > Impact Analysis.

    The Impact Analysis tool is invoked displaying TREND-KEY.

  7. Select TREND-KEY and click Impact Tracing.

    The Tracing Group Impacts dialog shows the progress of the trace.

    By default, Impact Analysis displays results by name. In the section Manual Impact Tracing, you traced an impact to a screen. Here Revolve has traced it for you. Let's see how the impacts for TREND-KEY affect BMS screens in the project.

  8. Click Options....

  9. Click the Display tab.

  10. Click Type .

    Figure 5-2: Display Tab

  11. Click OK.

    The results are now displayed according to their impact types.

    Figure 5-3: Impacts Displayed by Type

    Impacted screens, buffers, and synonyms are automatically traced and provided for your reference.

  12. Double-click Screens.

    The folder opens to display the impacted screens.

  13. Select the folder for PP3.BMS.

  14. Click View Source Code.

  15. Click Screen View in the Split Screen Editor .

    The Screen view for PP3.BMS is displayed in the lower window.

  16. Click Screen View again to return to the source code.

  17. Go back to the Impact Analysis window and double-click to expand PP3.BMS's folder.

    The traced chain of events that led to the impact is displayed. Each line of text that is displayed explains the movement of the screen to its impact with TREND-KEY. As you move down the trace, observe the corresponding code in the Split Screen Editor.

  18. Close all windows by clicking Window > Close All Windows .

5.5 Summary

In this session you:

5.6 Before Continuing

If you want to take a break before going on to the next session, you can close the project; or you can close Revolve, with or without closing the project.

Return to the Tutorials Map and choose which session to go on to next.

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