Tersus: Visual Debugging

Visual Debugging Date: Apr 6, 2020Tags:TraceIntroductionYou can trace the execution of a Tersus application visually on the same diagrams used to define the application, making it easier to understand the business logic and detect bugs.When working in trace mode, the Tersus Server records every step during the application’s execution. This recording ("trace") can then be played back to view the flow of the application and the value of each data element.Unlike regular debuggers, which can only move forwards, the Tersus tracing function acts like a “time machine.” You can move back and forth along the execution. If you reach a point where something looks erroneous, you can trace back to locate the root cause of the improper behavior.

Usage InstructionsVisual Debugging is performed in two steps:

Creating the Trace File (recording the execution steps)

Debugging the Application Using the Trace File (playback)

1. Creating the Trace FileVisual debugging utilizes a trace file – a recording of the steps performed by the Tersus Server while executing the application (typically, in response to user actions). The trace file records which elements of the application model have been activated, in what order, and what data passed between these elements.The creation of a trace file is initiated and terminated by the user of the application as follows:

The user launches the application to trace (in the browser, as usual).

The user works with the application until reaching the point/state in the application where debugging should start.

The user starts the trace by clicking the Start Trace icon (

) in the top-right corner of the browser (if the icon is not available, enter javascript:startTrace() in the browser's address bar). In response, the browser notifies the user of the trace file name, and the server starts recording the trace.

The user continues to use the application. The user actions and the resulting model execution are recorded in the trace file.

The user stops the trace by clicking the Stop Trace icon (

) (if the icon is not available, enter javascript:stopTrace() in the browser's address bar). The server stops updating the trace file, and the browser notifies the user that the trace file has been closed.

Note the following regarding trace files:

Trace file name & location
The trace file name is automatically generated in the format YYYY-MM-DD-nnnn (where YYYY-MM-DD is the date on which the execution started, and nnnn is an auto-increment counter which is reset each time the application is started in the Tersus Server).
If the trace file is created using the embedded Tersus Server, it is created in the work/trace folder of the application's project.
If the trace file is created using the standalone Tersus Server, it is created in the location defined in your application's context file (see the Deployment documentation for more details).
When an application is started in the server, all its existing trace files are removed from the trace folder.

Startup trace file
When the Tersus Server (embedded or standalone) starts an application, it automatically creates a startup trace file. This trace file includes tracing of any model which is modeled outside a View. This trace file is always created, regardless of any usage of the Start Trace/Stop Trace icons. The name of the startup trace file is of the format Startup-YYYY-MM-DD-HHMMSS (where YYYY-MM-DD and HHMMSS are the date & time, respectively, in which the server started application execution).

2. Debugging an Application Using the Trace FileOnce a trace file has been created, it should be loaded into the Tersus Studio in order to debug the model you want to trace, as follows:

Make sure at least one model of your application is open in the model editor (not necessarily the top model).

Switch to the Tersus Debugging perspective by selecting Window|Open Perspective|

Tersus Debugging.
(Note that the studio's window title includes the current perspective's name)

A new view,

Runtime Trace View, will be displayed below the model editor.

Click the Open Trace File button (

) to select a trace file you have created earlier.
By default you will be shown the contents of the work/trace folder, which is where the trace file is created when using the embedded Tersus Server. If the trace has been created using the standalone server, you should navigate to the location specified in the application's context file.

The trace view looks similar to the following:

All screenshots are based on the Requisition Management System sample application.
The user has opened the Open Requisitions view, clicked Start Trace, added a requisition (through the New Requisition button), then canceled the requisition (through the Cancel Requisition button), and clicked Stop Trace. Each row in the trace view includes the following fields:

Description - The element/action to which the row refers.

Details - Depending on the row's context, either the data handled or the number of times a certain element has been executed.

Time - The exact execution time.

Path - The location of the element in the model hierarchy.

The following are possible when using the trace view:

Click a row in the view to select a step
This will cause the model editor to zoom and highlight the applicable element in the model editor. In our example, if the user clicks the last row, Button 'Cancel Requisition' Started, the model editor will display the following:

Expand/Collapse a row
Clicking the

icon at the beginning of a row displays/hides the execution steps performed inside the matching element. For example, if the user expands the above mentioned row, the trace will look as follows:

Navigate the trace
Use the Right/Left arrows to zoom into or out of the current element (expanding/collapsing the trace as needed). Zooming in means you want to trace the steps within the element, while zooming out means you want to skip the details and move to the next element.
Use the Up/Down arrows to move along the trace. The model editor will keep in sync with the current row, displaying the matching element in the model diagram.

For example, pressing the down arrow 3 times will bring us to the following:

Display data applicable to the current row
If the data to which the row refers is not displayed in full in the Details column, press Enter to view it in full. For example, pressing enter on the above mentioned row will display the following:

3. Advanced Tracing Issues

If the start and stop trace icons do not appear (which is the case when the root system property html.customNavigation= true) tou can type javascript:startTrace() in the browser's address bar to start the trace and javascript:stopTrace() to stop the trace.

When trying to trace an activity that does not have any user interface (like Callable Services), the user can initiate a 'Trace All' mode by adding 'Trace/All' to the application's URL:

http[s]://host[:port]/application_name/Trace/All

To stop the 'Trace All' mode, enter the following URL:

http[s]://host[:port]/application_name/Trace/ResetSee Also:

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