UML activity diagram

The "activity diagram" displays business or software processes as workflows through a series of operations. These operations can be performed by people, software components, or computers.  The activity diagram can be used to describe various types of processes. The specific examples are as follows:  Business flow or workflow between the user and your system. For more information, see user requirement modeling.  The steps in a specific use case. For more information, see the UML use case diagram: Guidelines.  Software protocol, that is, the sequence of interactions allowed between components.  Software algorithms.  This topic describes the elements that can be used in the activity diagram. For more details about drawing activity diagrams, see UML activity diagram: Guidelines. For more information about how to draw a general modeling diagram, see How to: edit a UML Model and diagram.  The tables in the following sections of the read activity diagram describe the elements that can be used in the activity diagram and their main attributes. For a complete list of the attributes of these elements, see the attributes of the elements in the activity diagram.  The operations shown in the activity diagram and other elements constitute an activity. You can view the activity in the UML model resource manager. The activity is created when you add the first element to the graph.  When reading the graph, assume that there is a token or control thread that passes the connection line from an operation to the next operation.  Simple Control FlowYou can use branches and loops to display operation sequences. For more information about how to use the elements described here, see the "Description control flow" section of the UML activity diagram: Guidelines topic.        Shape Element Description and main attributes   1  Operation A step in the activity where the user or software can execute a task.  The operation can start when the token reaches all of its incoming streams. After the operation is completed, the token will be sent on all outgoing streams.  Body-specifies the detailed operation.  Language-the language of the expression in the body.  Local postconditions-constraints that must be met when execution is terminated. The target of the operation.  Local preconditions-constraints that must be met before execution starts.   2  Control Flow Display the control flow connection lines between operations. When interpreting the relationship diagram, assume that a token flows from one operation to the next operation.  To create a control flow, use the "connection line" tool.   3  Initial Node Indicates the first operation or the first operation in the activity. The token flows out from the initial node when the activity starts.   4  Final Activity Node It indicates the end of the activity. When the token arrives, the activity is terminated.   5  Decision Node A conditional branch in the stream. Has one input and two or more outputs. The incoming token is only displayed on one output.   6  Critical A condition used to specify whether a token can flow along a connection line. It is most commonly used in outgoing streams of decision nodes.  To set the critical value, right-click the stream, click "attribute", and set the "critical" attribute.   7  Merge nodes Used to merge streams split by decision nodes. It has two or more inputs and one output. Any token on the input will be displayed on the output.   8  Note Provides additional information about the elements it is linked.   9  Call action One operation is defined in detail in another activity diagram.  Issynchronous-if it is true, the operation is not performed until the activity ends.  Behavior-called activity.   (Not Displayed) "Call operation" Operation An operation that can be called on an instance of the class.    Activity The workflow depicted in the activity diagram. To view the attributes of an activity, You must select the activity in "UML Model Resource Manager.  Is read only-if it is true, this activity should not change the status of any object.  Is single execution-if it is true, this graph can be executed at most once at a time.    UML activity diagram Shows the activity diagram. To view its properties, click the blank section in the graph.   DescriptionThe name of the activity chart, the name of the file where the activity chart is located, and the name of the activity shown in the figure can be different.  Concurrent streamIt can describe the operation sequence executed at the same time. For more information, see "Draw concurrent streams ".      Shape Element Description   11  Forks Divides a single stream into concurrent streams. Each incoming token generates a token on each outgoing connection line.   12  Join Node Merge concurrent streams into a single stream. When each incoming stream has a waiting token, a token is generated in the output.   13  Sending signal operation One operation can send messages or signals to another activity or concurrent threads in the same activity. The message type and content can be viewed by the Operation title or the information specified in other annotations.  This operation can send data in the form of a signal that can be passed to an object stream or an operation in the input pin (16.   14  Accept event operations An operation that can be performed only after the message or signal is sent. The message type that this operation can receive can be seen by the Operation title or the information specified in other annotations.  If this operation does not pass in the control flow, it will generate a token immediately after receiving the message.  This operation can receive data in the form of a signal, and the signal can be transmitted in the object stream or output pin (17.  Isunmarshall-if this parameter is set to true, multiple output pins can be typed and data is unblocked. If it is false, all data is displayed on a plug-in.     Data StreamIt can describe the data flow from one operation to another. For more information about the elements used in this section, see the "draw data streams" section in the "Draw activity graphs Guide" topic.      Shape Element Description   15  Object Node Indicates the data passed through the stream.  Ordering-how to store multiple tokens.  Selection-call the process that filters data. The process can be defined in another graph.  Upper Bound-0 indicates that the data must be transmitted directly through the stream; * indicates that the data can be stored in the stream.  Type-type of the object to be stored and transmitted.   16  Input Pin Data that can be received during Operation execution.  Type-the type of the object to be transferred.   17  Output pin Indicates the data generated when the operation is executed.  Type-the type of the object to be transferred.   18  Activity parameter Node An object node through which data can be received or generated.  It is used when an activity is called by another activity, or when an operation or function is described in this relationship diagram.  Type-the type of the object to be transferred.   (Not Displayed) Object stream Displays the connection lines between operations and object nodes.  To create an object stream, you can use the "connection line" tool to link an input/output pin or object node to another element.  Selection-call the process that filters data. The process can be defined in another graph.  Transformation-a process that calls data conversion. This process can be defined in another graph.  Ismulticast-indicates that multiple receiver objects or components may exist.  Ismultireceive-indicates that input can be received from multiple objects or components.