Debugging Demystified: ESAPI App Strategies using Visual Studio
- mschmidt33
- 3 days ago
- 8 min read
Introduction to Debugging
Debugging is a powerful tool in software development. Debugging isn't just for squashing bugs-- it's about understanding the code's behavior, ensuring reliability, and enhancing performance. In the realm of Eclipse Scripting API apps, where the intricacies of software development and clinical practice merge, having a robust debugging strategy is essential. Whether you're using tried-and-true methods like inserting message boxes to monitor variable states, or you're diving into more sophisticated process of attaching your Visual Studio session to an Eclipse Treatment Planning System directly, each technique is a vital tool in a developer's toolkit.
At its core, debugging bridges the gap between theoretical design and practical implementation. It encompasses not only the identification of faults, but also the broader understanding of how different parts of your code interact. Theories in debugging often center on systematic isolation of variables, step-by-step analysis, and iterative testing -- all of which are critical for maintaining complex applications. As we explore these varied techniques-- from single file plugins that provide feedback when running them in Eclipse TPS, to more advanced breakpoint strategies with Visual Studio -- the goal is to equip you with a comprehensive approach that transforms challenges into learning opportunities.
Debugging is a dynamic, interactive activity that allows you to step through code execution and understand the interplay of different components in real time.
Debugging is similar to logging and unit testing in that they are all critical components of software development. Logging acts as an ongoing narrative of your applications execution, capturing events and states over time. To learn more about logging in software development, check out his prior blog post titled First Experiences Logging with NLog. Unit testing, on the other verifies that individual components function as intended under controlled conditions. Debugging, however, is an investigative process aimed at isolating and resolving unexpected behavior during runtime. Debugging is a dynamic, interactive activity that allows you to step through code execution and understand the interplay of different components in real time. These techniques complement logging and unit testing, but offer a more granular, immediate insight into issues that surface during live execution.
Debugging the Single File Plugin
Single file plugins are usually the starting point for ESAPI developers. The single file plugin contains all the C# code in a single code file. This file is then compiled "on-the-fly" by the Eclipse TPS, meaning it's dynamically converted into an executable class library that operates on the current data model of the open patient and treatment plan. Since the plugins run exclusively within Eclipse, the rich debugging environment provided by Visual Studio is off the table.
If as a developer, you find yourself utilizing single-file plugins solely to test output values ESAPI properties, I might recommend the ESAPI Explorer by Radformation as a means of testing property values broadly.
As a result, the most straightforward -- and perhaps only-- method of debugging a single file plugin is to manually insert a feedback mechanism directly into the code. One common strategy is to use the message box. With message boxes, developers can provide immediate, visual feedback during execution, indicating not only the current location of the code, but also the values of critical variables at that moment. This technique allows you to trace the execution path and quickly pinpoint areas where the behavior deviates from your expectations. If as a developer, you find yourself utilizing single-file plugins solely to test output values ESAPI properties, I might recommend the ESAPI Explorer by Radformation as a means of testing property values broadly.
Occasionally, the MessageBox may not be the most fitting tool for debugging single-file plugin applications. In the code below, the single file plugin is iterating through dose-volume histogram (DVH) data to generate a differential DVH:
public void Execute(ScriptContext context /*, System.Windows.Window window, ScriptEnvironment environment*/)
{
// TODO : Add here the code that is called when the script is launched from Eclipse.
// Find target volume for current plan.
PlanSetup plan = context.PlanSetup;
Structure target = plan.StructureSet.Structures.FirstOrDefault(s => s.Id == plan.TargetVolumeID);
DVHData dvh = plan.GetDVHCumulativeData(target, DoseValuePresentation.Absolute,
VolumePresentation.Relative, 1);
//DVH data is cumulative. Take derivative to get differential DVH.
List<Tuple<double,double>> cDVH = new List<Tuple<double, double>>();
int dvhIndex = 0;
foreach(var item in dvh.CurveData.Skip(1))
{
//get differental volume at dose.
double vol = item.Volume - dvh.CurveData[dvhIndex].Volume;
cDVH.Add(new Tuple<double, double>(item.DoseValue.Dose, vol));
dvhIndex++;
}
string dvhString = String.Join(",", cDVH.Select(c => String.Format("{0};{1}", c.Item1, c.Item2)));
MessageBox.Show("Differential DVH: " + dvhString);
}The output to the MessageBox is shown below:
When the debugging information is too complex for a simple message box, an alternative output method can be employed. For instance, if you need to review something visually, a UI component can be incorporated to display an image directly within the plugin's interface. Similarly, if you have large volumes of data to track-- the data would overwhelm the message box -- a better approach might be to output this information to a CSV or text file. That way, the data can be better organized and developers can analyze the data more effectively post-execution without cluttering the immediate user interface.
Instead of the MessageBox, write the output to a CSV file with the following code:
//MessageBox.Show("Differential DVH: " + cDVHString);
SaveFileDialog sfd = new SaveFileDialog();
sfd.Filter = "CSV files (*.csv)|*.csv|All files (*.*)|*.*";
sfd.Title = "Save Differential DVH";
if(sfd.ShowDialog() == true)
{
using (StreamWriter sw = new StreamWriter(sfd.FileName))
{
sw.WriteLine("Dose,Volume");
foreach (var item in cDVH)
{
sw.WriteLine(item.Item1.ToString() + "," + item.Item2.ToString());
}
}
}
Debugging tools in Visual Studio
Visual Studio's debugging environment provides a robust set of tools that can dramatically enhance your ability to understand and troubleshoot your code. One of the most fundamental features is breakpoints, which allow you to pause the program execution at specific lines of code. When a breakpoint is hit, you gain an opportunity to inspect the state of your application at that precise moment. The mouse can hover over variables to see their current values, providing an immediate sense of what's happening internally. Additionally, Visual Studio's Local's and Autos windows automatically display variables in the current context, making it easier to track changes and understand how data flows through your code.
Beyond simply pausing execution, Visual Studio offers an interactive environment to empower experimentation with code in real time. The Immediate Window, for instance allows developers to evaluate expressions, experiment with variable values, and even run some methods on the fly. This is particularly useful for testing short code snippets without having to modify source code files or recompile the entire application. In a similar vein, the C# Interactive Window provides a more expansive sandbox where testing basic C# concepts and language behavior can reinforce understanding of how different elements in a program behave. Python and MATLAB developers may appreciate these features as they behave in a REPL (Read, Evaluate, Print, Loop) fashion allowing users to see the immediate output to their queries on the very next line.
Conditional breakpoints in Visual Studio allow developers to pause execution when certain conditions are met, making it easier to isolate issues that occur under specific circumstances. To set one up, simply right-click an existing breakpoint and choose "conditions", where you can specify a condition such as a variable reaching a certain value or a specific expression evaluating to true. This targeted approach prevents code from stopping unnecessarily, streamlining the debugging process and helping developers focus on the precise moments a problem may arise. Such conditional debugging points are particularly useful in complex loops or when handling large datasets, as they help reduce noise and increase efficiency during a developer's investigation. In the example below, the debug point will only be triggered when the PTV structure is selected.
Together, these features create a powerful and integrated debugging experience. By combining breakpoints, real-time variable inspection, and interactive code evaluation, Visual Studio not only helps you identify and isolate issues quickly, but also enables you to experiment with potential fixes on the spot. Whether you're working on binary plugins, or stand-alone executables, these debugging capabilities can significantly streamline development workflows and improve code readability.
Debugging Workflows for Binary Plugins
Binary plugin applications require a special workflow for debugging. The core concept is to attach the Visual Studio IDE to the External Beam Planning application process. Visual Studio will listen for the compiled code execution and pause the execution when necessary. The following steps will summarize this process.
Ensure Eclipse TPS is running, and that no other binary plugin scripts are running on top of Eclipse.
It's best to start with a fresh build of the binary plugin. Build the binary plugin application.
Note: for those familiar with binary plugin applications, it may be advisable to either restart ARIA or change the assembly file name slightly to avoid the dreaded "...file is locked by ARIA Radiation Oncology... " compilation error.
From the Debug menu at the top of Visual Studio, choose the option Attach to Process...
Search in the list for ExternalBeam.exe. Select ExternalBeam.exe and click Attach.
Set the breakpoints as necessary. The rest of the debugging strategy relies on Visual Studio once the breakpoint is triggered.
Debugging Stand-Alone Executables
Stand-alone executables could also benefit from their share of debugging. While the debugging tools for binary plugins (once attached to Eclipse TPS) and stand-alone executables rely on Visual Studio's debugging features mentioned above, there are some special considerations when debugging any ESAPI application using Visual Studio.
The Visual Studio Instance must be on an Eclipse TPS environment: The debugging features in Visual Studio will require Visual Studio to be installed on the same environment where the script is to be run. Due to limitations with installations on clinical Eclipse TPS environments, this means debugging is limited to T-Boxes and research environments.
Methods from ESAPI can be run in debug mode: Debugging enables developers to test the output of ESAPI methods. Below see a couple of methods run on the "s" variable and also on the "_plan" from the Immediate Window.
Automation calls would still require approval and other prerequisites: Automation calls would not be allowed if the script requires approval, has not yet called patient.BeginModifications, or explicitly marked the script as write-enabled using the [assembly:EsapiScript(IsWriteable=true)] assembly attribute.
Use Conditional Breakpoints responsibly: Some objects in ESAPI cause large iterations to navigate through all possible conditions. Conditional breakpoints can slow the execution of the code significantly. For example, if iterating through thousands of DVH points in a high resolution DVH, the conditional breakpoint would have to investigate every DVH point to see if the condition has been met.
Debugging is a means of testing: Be sure to continue your other means of testing such as Unit Testing, integration testing, and implementing user feedback into bug fixes and new features.
Conclusion
In conclusion, robust debugging practices are at the heart of developing reliable ESAPI applications. Whether working with single file plugins or diving into more complex binary plugins and stand-alone executables, each method brings its own set of tools and strategies to the table. Single file plugins rely on creative, embedded feedback mechanisms—such as message boxes or file outputs—to provide immediate insights, while Visual Studio’s extensive debugging capabilities empower you to set breakpoints, inspect variables, and experiment with code in real time. This integrated approach ensures that each layer of your application can be scrutinized and refined for optimal performance.
By leveraging both the inherent capabilities of the Eclipse TPS and the powerful debugging features of Visual Studio, you can tailor your workflow to match the demands of each development scenario. Debugging not only helps in rapidly identifying and isolating issues but also enhances your understanding of the underlying code behavior—a critical factor in maintaining complex systems. Ultimately, a comprehensive debugging strategy transforms challenges into learning opportunities, leading to more resilient, efficient, and high-quality ESAPI applications.
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