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2 Editing SDL Diagrams

The SDL Editor is the tool with which you create the SDL diagrams and edit the graphical and textual contents of these diagrams. Additional windows, command shortcuts, SDL Grammar and syntax support and an SDL signal dictionary are provided so that you can operate the SDL Editor as efficiently as possible. This chapter describes how to edit SDL diagrams. For a reference to the SDL Editor, see chapter 23, The SDL Editor.

General

The SDL Editor supports two kinds of SDL diagrams:

The editing functionality that is available depends on what type of diagram the SDL Editor is handling.

This chapter describes the functionality the SDL Editor provides when editing remote diagrams.

In Figure 1 - Figure 3, you can find an example of remote diagrams (in the example, one system diagram and two block diagrams) and the resulting overview diagram.

Figure 1 : Remote System Diagram. 
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Figure 2 : Remote Block diagrams. 
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Figure 3 : Resulting Overview diagram. 
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Remote Diagrams

The SDL Editor is the tool used to edit SDL diagrams. The SDL Editor works with SDL diagrams in graphical form, SDL-GR, and allows graphical editing of symbols, lines and text.

You may open multiple windows in an SDL Editor to be shown at the same time; each window will hold an SDL page. This can be useful if you want to edit different diagrams and pages and refer between them, or if you want to see the interface between two processes on different hierarchical levels. This is the normal mode in which diagrams are edited.

Overview Diagrams

The SDL Editor can also be used to view SDL Overview diagrams. An SDL Overview diagram consists of a number of diagrams that are built up into a diagram subtree in which the symbols are drawn in a nested fashion, giving a more comprehensive overview of a required set of diagrams. You may have multiple SDL Overview pages associated to one SDL system, at different SDL levels, and thus presenting different views of the system. Overview diagrams are generated in the SDT Organizer (using the Generate SDL Overview command), and can be opened for display in the SDL Editor. Various parameters allow you to generate Overview diagrams to meet your requirements.

Once an SDL Overview diagram is generated, it cannot be modified in the same way that you would normally edit remote diagrams (unless you regenerate it). However, limited editing can be done on the text of overview diagrams in the SDL Editor.

Essentially, the SDL Overview Editor works in read-only mode with regard to graphical operations. Here are the general restrictions in editing Overview diagrams:

The functionality supported by the various menus is reduced in comparison to the SDL Editor when working on remote diagrams.

Tracing Simulations (Graphical Trace)

Graphical trace, GR trace, is a method to follow the execution of transitions in SDL-GR source diagrams. It is mainly intended to be utilized together with the simulator's StepSymbol command and should normally only be used for a small number of processes to limit the amount of information displayed. The GR trace facility will always show the next SDL symbol within the transition to be executed. After a nextstate or stop operation (e.g. between two transitions), the nextstate or stop symbol is still selected.

The GR tracing is activated from the SDT Simulator. The SDL Editor selects the symbol currently being executed. The Simulator automatically highlights the symbol, and it is scrolled into the viewport to be visible to the user. You can use either SDL to see what is being traced, or MSC to see the interaction between processes.

If you use an MSC to trace the simulation, the instances concept of MSC is mapped to the instances concept of SDL processes. The mapping rules which govern how SDL events are transformed into MSC symbols, lines and textual elements are described in "Mapping Between SDL and MSC" on page 248.

GR trace will take place in an SDL Editor containing the appropriate diagram. If the SDL Editor is open on the current SDL page, a new one is opened according to the following rules:

Compliance with SDL Rules

The SDL Editor complies with the SDL rules as defined in the ITU Z.100 recommendation. Virtually all parts of the recommendation are supported by the SDL Editor.

Syntax Rules when Editing

Some of the SDL syntax rules are enforced during editing when you create diagrams, add pages to these diagrams and append symbols and lines to your pages.

Next follow the syntax checks that are performed by the SDL Editor:

The SDL Editor does not force you to fill the contents of text attributes. Neither does the SDL Editor check any text with respect to syntactic rules, exception made from the kernel heading symbol.

Turning Syntax Checking on and off

The syntax checking on what symbols you are allowed to use and how you can interconnect symbols can be disabled and enabled again.

To disable or enable syntax checking:

  1. The operation applies on one diagram at the time. Therefore, make sure you are editing the diagram of your choice.
  2. Select the Diagram Options menu choice from the View menu. In the dialog which is issued, toggle the Syntax check button on or off, depending on your choice and click OK.
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    Note:  No Retroactive Syntax Checking                                  
    Turning the switch from off to on will not perform a retroactive syn   
    tax check. Only the objects that you insert while syntax checking is   
    enabled are checked.                                                   
    ---------------------------------------------------------------------
    

Pasting and Syntax Checking

Only symbols that are valid according to what is displayed within the symbol menu may be pasted into a page. Non-valid symbols will be omitted whether or not syntax checking is enabled.

Identical Symbols - Different Syntax

SDL contains some symbols which appear identical, but are distinguished by their syntax:

They are:

SDL Grammar Help

The SDL Editor provides a versatile context-sensitive support function - the Grammar Help Window. The grammar help window is available to assist you when entering and editing the syntax of SDL text elements that are correct according to Z.100 definition. It simplifies writing statements with the correct SDL syntax.

Figure 4 : Requesting SDL Grammar Help. 
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How to take advantage of the SDL Grammar Help facility is described on page 130.

Signal Dictionary Support

The SDL Editor also provides a means of access to a signal dictionary where the signals that are already defined can be accessed. The Signal Dictionary Window provides functions for listing SDL signals that are available when looking up or down in the SDL hierarchy or by looking at the current diagram. Also, you can ask the tool to list signals that are used in the current diagram or defined and visible according to the SDL scope rules.

Furthermore, the signal dictionary has the ability to import messages from a Message Sequence Chart (each MSC message will be mapped to an SDL signal) and to import an external signal dictionary.

Figure 5 : Requesting Signal Dictionary Support. 
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For more information on this topic, see "Using the Signal Dictionary" on page 134.

Starting the SDL Editor

You start the SDL Editor from the SDT Organizer. In most cases you will start and access a diagram that forms a part of an existing system. You may also want to start the SDL Editor and create a new diagram (see "Creating a Diagram" on page 39).

Before an SDL Editor can be started, the following points must be adhered to:

Starting the SDL Editor on an SDL Diagram

To start the SDL Editor on an SDL diagram (which is symbolized by an icon in the Organizer diagram structure), any of the following methods can be used:

Once the SDL Editor has started, the requested diagram data will be read from disk, a window will be opened on that diagram and the viewport will be positioned at the upper left portion of the first page to be read.

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Note:                                                                   
It is possible to specify what page to open first with an option. See   
"Designating the Page to Open" on page 57.                              
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Starting an SDL Editor on an SDL Page

To open an SDL Editor on a specific page, the SDL pages must be visible in the Organizer diagram structure. To start the SDL Editor and read a specific page:

Starting an SDL Editor on a Collapsed Diagram

In the Organizer, there may be a subset of diagrams that have been collapsed. This means they are hidden from view and situated hierarchically beneath one diagram, the icon of which is showing in the diagram structure.

To be able to start an SDL Editor for the required diagram, you first need to expand the subset of diagrams using one of the Expand options located in the View menu of the SDT Organizer's Menu Bar.

Once you can see the diagram required, you may proceed as described in the two previous sections ("Starting the SDL Editor on an SDL Diagram" and "Starting an SDL Editor on an SDL Page").

Exiting the SDL Editor

To exit the SDL Editor:

  1. Select the Exit command from the File menu. If the SDL Editor holds any diagram that has been modified but not saved, a dialog is issued, prompting you to save the changes before the application terminates:
    Figure 7 : Exiting the SDL Editor. 
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  2. The dialog informs you about the type and name of the diagram in turn to be saved. Depending on what if you want to save the changes or not:
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Footnotes

(1)
This behavior can be modified using the Preference Manager.
 
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