IBM
Contents Index Previous Next



Symbols and Lines in MSC Diagrams


Symbols in MSC Diagrams

Symbol Name Explanation

Text

Contains comments relevant for the diagram. Is not connected to any other symbol.

Comment

Contains comments relevant for a part of the diagram. Is connected to a symbol, a message sending or a message reception.

Instance head

Represents an instance of something that can communicate by sending and receiving messages. The "start symbol" for a created or an already existing instance.

Instance end

Used for graphically ending an instance axis without terminating the represented instance.

Message

Represents a signal sending from one instance to another. Is connected to at least one instance axis. Usually connected to an instance axis in both ends.

Condition

Represents a system or process state, or indicates that a certain condition is true. Contains a name of the represented state or condition. Is initially connected to one instance axis, but should often be connected to all.

Timer

Represents the use of a timer in an instance. Is connected to an instance axis. One symbol represents both a timer set and either a timeout or a reset.

Action

Is a kind of text symbol and is connected to an instance axis. Describes something that is happening in the instance.

Create process

Describes the creation of an instance. The arrow should go from an instance axis (the creator) to an instance head (the creator instance). The instance head is created when the create process symbol is initially laid out.

Process stop

Terminates an instance. The instance ceases to exist. Is connected to an instance axis.

Coregion

Creates a part of an instance axis where the order of received and sent signals is undefined. Is connected to an instance axis.

MSC reference

References another MSC or HMSC diagram in the same group of MSC diagrams. Contains the name of the other diagram. Is initially connected to one instance axis, but can be connected to several.

Inline
expression

Is used for specification of alternative or optional parts (that is, message sending sequences) which are contained in the symbol. Is initially connected to one instance axis, but should most likely be connected to several.

Inline expression separator

Creates a new partition in an inline expression symbol. Initially, the inline expression symbol only contains one partition.

Lines in MSC Diagrams

Line Name Explanation

Message

Is used for defining a message sending and/or a message reception. Is at least connected to one instance axis, but is usually connected to an instance axis in both ends. Create it from the symbol menu.

Create
process line

Is used for defining the creation of an instance. The arrow should go from an instance axis (the creator) to an instance head (the created instance). Create the process line from the symbol menu. When the create process arrow is initially laid out, the instance head is created.

Comment line

Associates a comment symbol with another symbol. To create it, select the comment symbol and drag the line handle to another symbol. Note that it is also possible to attach the comment symbol to a message sending or a message reception, by dragging the line handle to a connection point between a message and an instance axis.


http://www.ibm.com/rational
Contents Index Previous Next