Basic Activity Diagram with Exception Handler

The Basic Activity Diagram with Exception Handler pattern creates elements and an Activity diagram that contains a series of Actions and Control Nodes (Initial, Final, Decisions etc.) connected by Control Flows indicating the sequence in which the Actions are fired. An exception handler is an element that allows an Action (protected node) to be protected by specifying an alternate action to execute when a certain condition or event occurs in the execution of the protected node. 

Figure 1. Shows an Activity diagram with a number of Actions and Control Nodes (Initial, Final, Decision) connected by Control Flows. An Exception Handler receives an incoming flow when an exception occurs matching its type.

Discussion
The purpose is to allow Business analysts and other stakeholders to create visual representations of how an Activity carries out its work by defining a sequence of Actions.  The sequence is shown by the Control Flow relationships. An Exception .Handler provides a mechanism for a modeler to specify an alternate action to deal with an unusual event during the execution of an action

It is commonly used during the analysis phase of an initiative to show how the work described by an Activity is carried out by a sequence of Actions. The diagrams would not typically be created for every Activity but rather for a small number where it was important to articulate how the work was carried out.  Its uses include to:
•	Specify an alternate action to be carried when an exception event occurs with a matching type..

The following is a list of some things you may want to do when working with this pattern.
•	Rename the elements and Diagram to suit the initiative.
Rename the Actions and the Pseudo nodes (initial, Final, Decisions etc.) to suit the initiative.
Add further elements where required to extend the semantics of the diagram.

The following is a list of some things you may want to do when working with this pattern.
•	Add Object Nodes (using Pins) to show information is consumed and created by the Actions.
Create trace relationships to the components that will ultimately carry out the work defined by the Activities and the Actions.
Create documentation that will help disseminate the information contained in the diagram to other team members.

Useful Workspace Layouts Core | Core Modeling

Reference
The following help topics will assist you learn about how to work with this pattern.
Activity Diagram
Control Flow
Object Flows in Activity Diagrams
Activity Parameter Nodes
Action Pin
Working with Diagrams
Changing Element Appearance
Changing Diagram Layout

The following tools are useful when working with this pattern.
Specification View
The Specification View can be used as a way of working with the Components and Interfaces particularly when there are a large number of elements as is typically the case when describing a system of any appreciable size. For more details see the Specification View help topic.
Document Generator
The Document Generator is a powerful facility in Enterprise Architect that allows a Database Engineer or other stakeholder to create high quality corporate or technical documentation directly from the model, suitable for internal or external audiences. For more details see the Documentation help topic or the more general topic on Model Publishing.
Hand Drawn and Whiteboard Diagrams
The Hand Drawn and Whiteboard Mode are display options available for any diagram that changes a system-drawn diagram to appear as though it was drawn by hand and, optionally, hand drawn on a whiteboard. It is a powerful device to engage an audience by presenting the diagram in a rough and more immediate style giving the impression that it is just a sketch that can be changed. For more details see the Hand Drawn and Whiteboard Mode help topic.
Alternate and Images for Diagram Elements
Most standard elements allow an alternate image to be defined for an element that will be used in place of the graphical notation for the element either on a selected diagram or as a default on all diagrams. For more details see the Using the Image Manager help topic.
Compiled Simulator
The Compiled Simulator provides a number of facilities for working with Executable State Machines. This includes generating the state models to a variety of programming language code, building and running a simulation. Analyzer Scripts can be configured that determine how code is generated, compiled and executed for the Executable State Machine. The generated code can be viewed and edited using the built-in code editor and the execution analyzer can be used to debug running code. For more details see the Using the Compiled Simulation Panel help topic.
Element Discussions
The Element Discussion facility is a fully featured collaboration tool allowing modelers and model viewers and reviewers to communicate with each other directly inside the repository. Modelers using the full client or occasional viewers using WebEA can both post and reply to discussions and communicate and engage in chat. For more details see the Element Discussions help topic.
Pan and Zoom
The Pan and Zoom facility is one of the tools that can be used to navigate around a large diagram. Often the resolution of a diagram must be reduced to ensure it is wholly visible but by using the Pan and Zoom window you can leave the diagram at a readable resolution and pan around to areas of interest zooming in when necessary. For more details see the Pan and Zoom help topic.
Diagram Legends
The Diagram Legend facility is useful for manually or automatically changing the appearance of elements and connectors on a diagram. A legend can be added from the Common Toolbox and configured to codify the fill and line color and line thickness. This is a powerful way to add meaning and expression to a diagram and is particularly expressive when applied automatically based on element or connector properties. It can be used with a number of specialized diagrams such as roadmaps to create a powerful visualization.  For more details see the Diagram Legends help topic.

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