Syntax of Sequence Diagram Definitions

Sequence diagrams consist of objects, their lifelines (also known as smimming lanes), and the exchanged messages. Sequence diagrams are defined in UMLGraph using the pic syntax.

A sequence diagram file must start with the sequence:

.PS

copy "sequence.pic";

The .PS marks the beginning of pic commands. The sequence copy "sequence.pic"; loads the macros defining the sequence diagram operations. The file sequence.pic, part of the UMLGraph distribution, must exist in the directory where pic2plot will be executed.

Sequence diagram files must end with the sequence:

.PE

The sequence diagrams are defined by calling function-like pic macros. Each function call is terminated with a semicolon. Space is not significant between macro calls; on the other hand adding a space character between a macro's arguments can lead to surprises and should be avoided. Objects are referenced using variable-like alphanumeric identifiers. Strings are enclosed in double quotes.

As an example, the following defines an object O that will be identified in the diagram as o:Toolkit

object(O,"o:Toolkit");

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