Debugger Components

The Visual Studio debugger is implemented as a VSPackage and manages the entire debug session. The debug session comprises the following elements:

• Debug Package: The Visual Studio debugger provides the same user interface no matter what is being debugged.

• Session debug manager (SDM): Provides a consistent programmatic interface to the Visual Studio Debugger for the management of a variety of debug engines. It is implemented by Visual Studio.

• Process debug manager (PDM): Manages, for all running instances of Visual Studio, a list of all programs that can be or are being debugged. It is implemented by Visual Studio.

• Debug engine (DE): Is responsible for monitoring a program being debugged, communicating the state of the running program to the SDM and the PDM, and interacting with the expression evaluator and symbol provider to provide real-time analysis of the state of a program's memory and variables. It is implemented by Visual Studio (for the languages it supports) and third-party vendors who want to support their own run time.

• Expression evaluator (EE): Provides support for dynamically evaluating variables and expressions supplied by the user when a program has been stopped at a particular point. It is implemented by Visual Studio (for the languages it supports) and third-party vendors who want to support their own languages.

• Symbol provider (SP): Also called a symbol handler, maps the debugging symbols of a program to a running instance of the program so that meaningful information can be provided (such as source-code-level debugging and expression evaluation). It is implemented by Visual Studio (for the Common Language Runtime [CLR] symbols and the Program DataBase [PDB] symbol file format) and by third-party vendors who have their own proprietary method of storing debugging information.

The following diagram shows the relationship among these elements of the Visual Studio debugger.

In This Section

• Debug Package
  Discusses the debug package, which runs in the Visual Studio shell and handles all of the UI.

• Process Debug Manager
  Provides an overview of the features of the PDM, which is the manager of the processes that can be debugged.

• Session Debug Manager
  Defines the SDM, which provides a unified view of the debug session to the IDE. The SDM manages the DE.

• Debug Engine
  Documents the debugging services that the DE provides.

• Operational Modes
  Provides an overview of the three modes in which the IDE can operate: design mode, run mode, and break mode. Transition mechanisms are also discussed.

• Expression Evaluator
  Explains the purpose of the EE at run time.

• Symbol Provider
  Discusses how, at implementation, the symbol provider evaluates variables and expressions.

• Type Visualizer and Custom Viewer
  Discusses what a type visualizer and custom viewer are and what role the expression evaluator plays in supporting both.

Related Sections

• Debugger Concepts
  Describes the main debugging architectural concepts.

• Debugger Contexts
  Explains how the DE operates simultaneously within code, documentation, and expression evaluation contexts. Describes, for each of the three contexts, the location, position, or evaluation relevant to it.

• Debugging Tasks
  Contains links to various debugging tasks, such as launching a program and evaluating expressions.

See Also

Other Resources

Getting Started with Debugger Extensibility