Previous Chapter 2 Editing SDL Diagrams

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:

There is no symbol menu.
The text window is hidden by default(1) and must be shown on demand.
Only textual elements can be modified, not symbols and lines.

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:

If an SDL Editor is active, the GR tracing is performed in this SDL Editor. Otherwise, the SDT Organizer will start an SDL Editor.
If the SDL Editor does not hold the page, but if the diagram can be found in the Organizer, then the page will be opened by the SDL Editor.
If the Organizer cannot find the diagram, or the SDL Editor cannot find an appropriate symbol to select, due to, for example, modifying the diagrams after the generation of the simulator, error messages will be issued by the SDT Organizer or SDL Editor, but the simulation program will continue to execute without tracing graphically.

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 checks that names on diagrams and pages adhere to the SDL definition.
The type of a page that you add to a diagram must comply with the diagram type.
The set of the symbols you are allowed to append to a page is in accordance to the page type. Also, symbols ensures that are interconnected in a way that is syntactically correct.
- You can toggle the two last syntax checks on and off in a dialog box from the Diagram Options menu choice on the View menu.

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:

The operation applies on one diagram at the time. Therefore, make sure you are editing the diagram of your choice.

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.                                                   
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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:

The in connector and the out connector
The continuous signal and the enabling condition.

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:

The SDT Organizer must be up and running.
If no diagram structure of diagrams is showing in the SDT Organizer window, then one must be activated (using the View Options in the Organizer).
If a diagram structure is showing, it must contain at least a root diagram.
- If the Organizer does not provide any Root diagram, then you must assign one with the Add Diagram command. See page 1087 in chapter 22, The SDT Organizer for how to do this.
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Figure 6 : A Diagram Structure in the Organizer. 
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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:

Select the icon representing the SDL diagram by clicking on it (or clicking on the text line denoting the file name, next to the icon). Then select the Edit Diagram menu choice from the Organizer's Edit menu.
Point to the icon and press the right mouse button. This activates a pop-up menu. On that pop-up menu, select the Edit Diagram menu choice.
Double-click on the icon representing the diagram to be opened.

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:

Select the icon representing the SDL page by clicking on it. Then select the Edit Page menu choice from the Organizer's Edit menu.
Point to the page icon and press the right mouse button. This activates a pop-up menu. On that pop-up menu, select the Edit Page menu choice.
Double-click on the icon representing the page to be opened.

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:

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:
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Figure 7 : Exiting the SDL Editor. 
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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:
- Click Save to save any changes made to the current diagram. Once the diagram is saved, the SDL Editor will prompt you to save the next modified diagram, alternatively exit if there are no more diagrams to be saved. If a diagram has never been saved on file, the tool will prompt you to specify a file (see "Saving a Newly Created Diagram" on page 47).
- Click Save All to save all changes made to all diagrams. Once all diagrams are saved, the SDL Editor will exit. If a diagram that the SDL Editor holds has not yet been assigned a name, the tool will prompt you to assign a file before saving it.
- Click No Save to close the current diagram without saving it. The SDL Editor will then prompt you to save the next modified diagram, alternatively exit if there are no more diagrams to saved.
- Click Exit, No Save to exit the SDL Editor without saving any diagrams.
- Click Cancel if you want to change your mind and continue the SDL Editor session.

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Footnotes

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

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