UML-activity diagram

Activity diagram

Activity diagram (dynamic diagram) is a workflow that clarifies the implementation of business use cases.

Activity diagram in Business Case Model

The Business Use Case workflow describes the work that must be done by the business to provide the required value to the Service's business leading role. Business Use Cases are composed of a series of activities that generate certain artifacts for the business lead. A workflow usually includes a basic workflow and one or more alternative workflows. The workflow structure is described using an activity diagram.

The workflow activity diagram is used to study the sequence of tasks or activities to be executed when the business objectives are achieved. An activity can be a manual task or an automatic task. It can complete a work unit.

An activity chart is a special form of a state chart. All or most of these statuses are active, and all or most transfers are triggered immediately when the activity in the source status is completed.

1. Basic activity diagram

An activity chart may contain the following elements:

Activity Status indicates that an activity or step is executed in the workflow.
Transfer indicates the order of various activity states. This transfer can be called a completed transfer. It is different from general transfer because it does not need obvious trigger events, but is triggered by completing the activity (indicated by the activity status.
The decision defines a set of alert conditions for it. These alert conditions determine which of the alternative transfers will be performed after the activity is completed. You can also use the judgment icon to indicate the position where the thread is merged. The decision-making and alert conditions enable you to display alternative threads in the workflow of the business case.
The synchronous signal bar is used to display parallel branch streams. The synchronous probe bar allows you to display parallel threads in the workflow of the business case.

Activity diagram of the "Personal Registration" business case in the "Airport registration" Business Case Model

2. Condition thread

The alert condition is used to indicate that a thread in a group of parallel threads is conditional. For example, in the above "Personal Registration" example, the registered passenger may be a customer who frequently takes a flight. In this case, you need to reward him with flight miles.

Activity diagram of the "Personal Registration" business case in the "Airport registration" Business Case Model

3. nested activity diagram

One activity status may reference another activity chart, because the latter shows the internal structure of the former. In other words, you can nest an activity chart. You can display subgraphs in the activity status or make the activity status reference another graph.

Activity chart nested in activity status

If you want to show all workflow details in a graph, you can display subgraphs in the active state. This is a convenient way. However, if the displayed workflow is complex, the activity diagram is hard to understand.

Alternatively, you can place the subgraph in a separate graph and then let the activity state reference it.

To simplify the work flow chart, you may need to place the subgraph in a separate graph and then let the activity status described in the subgraph reference it.

4. Use swimming Channels

You can use a vertical solid line to divide an activity chart into a swimming track. Each Lane represents the responsibility of a part of the entire workflow, which is executed by a department of the organization. A swimming track can be implemented by a group of classes in the organizational unit or business object model.

The sorting between lanes does not affect semantics. One track is assigned for each activity status, and the transfer may span several lanes.

The above activity diagram shows the Business Use Case workflow that represents the general sales process. In this example, the Lane represents each department in the Organization.

5. Example

Which of the following is used in the workflow activity diagram and text description? It depends on your work habits and whether you think in charts. Some people tend to first outline the structure in a graph, and then use the text for detailed description. Others may be willing to define the outline of the activity status first, and then define the structure using the diagram after an agreement is reached.

Another proper question is whether you need both text documents and graphs. The activity diagram technology does allow you to write brief descriptions of the status of each activity, which makes the workflow text conventions useless. In this case, you need to maintain a high degree of sensitivity to the stakeholders and their expected protocol formats.

A sample activity diagram is provided to describe the workflow of the Business Use Case "Proposal Process" defined in Guide: Business Use Cases. We use it to illustrate how the activity diagram helps deepen our understanding of the workflow. This example is from an organization that sells Telecom Network Solutions. Each solution is tailored to the customer.

Activity diagram of the business case "Proposal Process"

The activity status named "initial opportunity work" contains three sub-steps that can be executed in parallel. This is illustrated in a subgraph of the activity status.

The subgraph of the activity status "initial opportunity to work. You can choose to develop a sales plan, which is described by the alert conditions in the upcoming transfer.

The activity status can represent a large process (with sub-structures) or a relatively small process. If you are using an activity diagram to define the workflow structure, do not represent all structural layers in the activity diagram from the top to the bottom. This may make the activity diagram very difficult to understand (if multiple independent subgraphs are used, it will make it hard to understand multiple graphs ). The entire workflow should be outlined in a graph whenever possible. A few of the activity states can have subgraphs.

 

Activity diagram in Business Object Model

The activity diagram in the business case model further describes the symbols used in the activity diagram. This section describes how to use symbols to describe the implementation of business use cases.

The activity diagram of business case implementation is used to study the sequence of tasks or activities that fulfill the business objectives, and these tasks or activities can also implement the conventions between external business protagonists and internal business roles. An activity is a task that executes a unit of work. It can be executed manually or automatically.

Activity chart help:

Provide reasons for introducing the information system into the business and understanding of this initiative.
Determine the target for implementing the Business conversion mechanism of the system development project.
It proves that investment in automation based on detailed business process indicators is correct.

Compared with a sequence diagram (which can be considered to have a similar purpose as an activity diagram), an activity diagram that contains a swimming track and an object stream focuses on how to split responsibilities into classes, A sequence chart helps you understand how and in what order each object interacts. The activity diagram focuses on workflows, while the sequence diagram focuses on the processing of business entities. The activity diagram and the sequence diagram can be used as complementary techniques, where the sequence diagram is used to indicate what happens in the activity state.

1. Use a swimming track

If you use a lane and the lane is coupled with the class (mainly the business role) in the business object model, you can use an activity diagram to record the Business Use Case implementation, rather than the business use case.

As an example, we provide an activity diagram for implementing the "Proposal Process" of Business Use Cases. For instructions on this business case, see Guide: business case.

Business Case Implementation of "Proposed Process"

By checking the people who have assumed a specific role (Business role) and the activities they perform, the activity diagram shows you in detail what happened in the business. For an application development project, these graphs help you understand the business areas that the new application will support or affect. They help establish connection points between the proposed new system, and these connection points also generate system use cases.

2. Use object stream

In this section, object streams are used to show how to create and use business entities in a workflow. The object stream allows you to display the input and output of the activity status in the activity diagram. This symbol has two elements:

The object stream status indicates the object of a class. This object participates in the workflow represented by the activity diagram. This object can be the output of an activity or input of many other activities.
An object stream is a control flow in which an object stream state is used as input or output.

Object stream symbols not only indicate the existence of the object, but also indicate its specific State. The same object can be controlled by a large number of continuous activities that change the object state. After that, the object can appear multiple times in the active diagram, and each time it appears, it indicates different states in its life cycle. The state of this object at each point can be placed in parentheses and appended to its class name.

The general sales process represented by an object stream is used to explain how the order status changes during the workflow execution. See Guide: Activity diagram in Business Case Model

An object stream status may be expressed as the target of an object stream (transfer) and the source of Multiple object streams (transfer.

Activity diagram of the proposed process, which uses an object stream to describe the core business entities involved

The object stream can be compared with the data stream in the workflow of the business case. Unlike traditional data streams, object streams exist at a specific point in the activity diagram.