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Windows Workflow Foundation Glossary for .NET Framework 4

This topic applies to Windows Workflow Foundation 4 (WF4).

The following terms are used in the Windows Workflow Foundation documentation.


Term Definition


A unit of program behavior in Windows Workflow Foundation. Single activities can be composed together into more complex activities.

activity action

A data structure used to expose callbacks for workflow and activity execution.


Defines the data flow into and out of an activity. Each argument has a specified direction: in, out, or in/out. These represent the input, output, and input/output parameters of the activity.


The point at which an activity can pause and wait to be resumed.


A group of actions designed to undo or mitigate the effect of previously completed work.


The mechanism for routing messages to a workflow or service instance.


A construct that takes in one or more arguments, performs an operation on the arguments and returns a single value. Expressions can be used anywhere an activity can be used.


A well-known modeling paradigm that represents program components as symbols linked together with directional arrows. In the .NET Framework 4, workflows can be modeled as flowcharts using the Flowchart activity.

long-running process

A unit of program execution that does not return immediately and may span system restarts.


Saving the state of a workflow or service to a durable medium, so that it can be unloaded from memory or recovered after a system failure.

state machine

A well-known modeling paradigm that represents program components as individual states linked together with event-driven state transitions. Workflows can be modeled as state machines using the StateMachine activity.


Represents a group of related bookmarks under a common identifier and allows the runtime to make decisions about whether a particular bookmark resumption is valid or may become valid.

type converter

A CLR type can be associated with one or more System.ComponentModel.TypeConverter derived types that enable converting instances of the CLR type to and from instances of other types. A type converterr is associated with a CLR type using the System.ComponentModel.TypeConverterAttribute attribute. A TypeConverterAttribute can be specified directly on the CLR type or on a property. A type converter specified on a property always takes precedence over a type converter specified on the CLR type of the property.


Represents the storage of some data that must be saved and accessed later.


A single activity or tree of activities invoked by a host process.


eXtensible Application Markup Language