This chapter contains a brief introduction to ORCA1 and SDT and their functionality.
After reading this chapter, you may want to familiarize yourself with ORCA and SDT: starting the tools, proceeding with a small example, or reading about what is new in this release in comparison to earlier versions. You are then recommended to study the following chapters:
ORCA and SDT are developed and marketed by Telelogic. Our company has been a firm supporter of languages like SDL, MSC and UML for a long time. We cooperate with ITU and OMG in the ongoing work of improving the languages and with ETSI in defining international standards in the field of communication protocols.
We initiate and participate in international research programs on how to use the languages in different application areas (such as the European Community programs RACE, ESPRIT and EUREKA, as well as the Swedish national IT program).
Our experience and know-how in these areas is put to practice when we develop software engineering tools that support the languages. Our family of tools are known as Telelogic Tau.
Tools for design and specification languages must be able to create, maintain, and verify a specification with respect to the language syntax and semantics. It is also fundamental that the tools can simulate, validate and generate application code to other high level languages.
To be able to perform a complete development cycle, the tool should support early analysis phases, and the move from object-oriented analysis to SDL design.
The tool should be able to export and import information from other SDL tools. Major documentation standards or de-facto standards should be supported.
The tool should provide an intuitive and consistent graphical user interface which reduces learning time and makes it easy to work with the tool. Besides the graphical user interface, a batch facility should allow to process a large amount of information without user interaction.
A powerful, context-sensitive Help facility should be provided, freeing you from time-consuming browsing through user documentation in search for the topic of interest.
ORCA and SDT can do all of this, and much more.
Figure 16 : Overview of ORCA and SDT (not all features are supported in Windows)
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ORCA and SDT are products in the Telelogic Tau family, which also includes the product ITEX.
Telelogic Tau consist of a number of separate tools that process information. The tools are integrated using a selective broadcast integration mechanism, making it possible to design a highly integrated system from separate tools. This approach also makes it possible to add new tools without creating any conflicts with the existing tools. In addition, the integration between two separate tools can be easily enhanced, and tools can communicate with each other over a network.
The interface that ties the tools in Telelogic Tau is called The PostMaster. The parts of the Postmaster interface that are of interest for the users, are documented so that you can read about how to integrate your own tools with Telelogic Tau.
On UNIX, the SDT Batch Facilities are commands that you type from the OS prompt. These facilities take advantage of the Postmaster and pass messages to the tools, ordering the individual tools to process information as required. The batch facilities support the following operations:
The software license server controls the licensing of the tools included in Telelogic Tau. This is performed through a floating license mechanism based on a third party software, FLEXlm®2. The current license numbers along with a key are stored on a text file, which is distributed at installation of the software. This provides a flexible way of upgrading licences and adding new license agreements, as well as allowing you to keep track of the actual usage of the tools you have purchased.
FLEXlm supports multiple tools (even from different tool manufacturers) sharing the same license server, so Telelogic should not cause any problems when installing it into your computer environment.
There is also another software license mechanism, CopyControl, employed for stand-alone PCs.
For increased flexibility in the use of licenses and to prevent started but unused tools from holding licenses, an optional timeout feature can be enabled. This will automatically release licenses when a user has been idle during a selectable interval.
For more information on license mechanisms, see A Primer on Licensing.
ORCA and SDT share a set of tools common to Telelogic Tau:
ORCA comprises the following tools:
SDT comprises the following graphical tools:
The following additional tools and facilities are available:
In order to properly use Telelogic Tau, you need to understand the basics for how the information is organized.
SDT primarily handles SDL information in the graphical representation, SDL-GR. The major advantage that follows this approach is that you are free to apply any graphical style guide to your diagrams since SDT lets you position symbols and shape lines the way you like.
Each SDL diagram consists of a number of diagram pages. An SDL diagram page may contain references to other SDL diagrams. This allows you to build a hierarchical structure which adheres to the SDL syntax rules. See Figure 17.
Figure 17 : Organization of SDL information
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Each diagram stored on its own individual file. An SDL structure is built up from a number of these SDL files. These files are logically tied together by SDT, in order to constitute a coherent SDL structure. This process is managed by the Organizer. SDT can manage several separate SDL structures at the same time.
You may also include SDL-PR files into an SDL-GR structure. Transformation of SDL-GR to SDL-PR and vice versa is supported.
Message Sequence Charts are mainly handled in the graphical representation, MSC-GR.
In contrast to SDL diagrams, MSCs are not paginated and cannot build a hierarchical structure. However, an MSC diagram can reference other MSCs (or HMSCs, see below), but without implying any structure between them.
MSC diagrams may be managed as entities of their own. The Organizer also supports including MSCs in an SDL structure using the concept of associated documents.
Telelogic Tau allows reading and writing of MSCs expressed in the textual form, MSC-PR. Both the instance-oriented and event-oriented forms are supported, according to the recommendation.
In contrast to "plain" MSCs, High-level MSCs (HMSCs) are paginated, but they cannot build a hierarchical structure visible in the Organizer. However, an HMSC diagram can reference other HMSCs or MSCs, but without implying any structure between them.
Telelogic Tau has the ability to read and write SDL and MSC textual files, SDL-PR and MSC-PR. The primary purpose is to enable importing and exporting of SDL and MSC information, rather than to provide an alternative storage format, since the layout and exact appearance of a diagram is lost when stored in PR format and read back again.
Telelogic Tau also use the PR formats as temporary storage formats when processing information.
SDL-GR diagrams can be converted to and from CIF (Common Interchange Format) files, by using CIF converters supplied with SDT. CIF is an extension to SDL-PR that also stores the graphical layout information. However, CIF files cannot be managed directly by SDT.
Object Model (OM) diagrams may be managed as entities of their own, or grouped together using the concept of modules in the Organizer.
OM diagrams are paginated, but does not contain any structure information. However, a scope concept is used to allow the same object class to be defined in more than one OM page or diagram. All diagrams and pages within the scope are considered when the complete definition of a class is needed. OM diagram belong to the same scope if they are managed in the same module in the Organizer.
State Chart (SC) diagrams are paginated, but does not contain any structure information, nor any references to other diagrams. They are always managed as entities of their own.
Telelogic Tau handles text documents in the form of plain ASCII files. Telelogic Tau uses the file extension of text files to determine the type of text file. Telelogic Tau recognizes text files as C header, ASN.1, or IDL specifications, or as plain text files.
Text documents are managed as entities of their own, but C header, ASN.1, and IDL specifications can be linked to the rest of the system by using the concept of dependency links. In this way, these text documents can be analyzed and translated to SDL-PR format.
A text document can also be a build script, containing commands to in detail control the analyze and code generation process in SDT.
Once Telelogic Tau is up and running, you may work on individual documents, regarding them as individual objects of their own. However, this requires that you keep track of each individual file.
When the amount of documents increases, this process tends to become rather complicated, in particular when introducing inheritance and specialization between SDL diagrams, and dependency links between different document types.
To cope with this problem and as a means to ensure the consistency of a document structure, the system file is introduced. The system file is managed by the Organizer.
The system file holds the information about the SDL structure and all other documents included in a system. It also keeps track of the file bindings, i.e. what file a particular document is stored on, and the dependency links between the documents. When working on your documents, the Organizer keeps track of the changes you apply and updates the system file accordingly.
A graphical approach is used, in order to display the contents of the system file in the Organizer. Documents may be freely organized into chapters and modules (within chapters) to keep related documents together.
Connections between documents in different chapters, modules and SDL structures can be made in the form of associations and dependency links.
In addition to the properties mentioned above, the system file may store information about what options you have set up for the document structure that is managed by the system file. Typically, analysis and code generation options are stored in the system file.
The Link Manager in keeps track of all link endpoints and implementation links in the system. This link database is stored on a separate link file, which is referenced from the system file.
Control unit files facilitate multiuser support when you work with an SDL system. They contain structure information for a subset of a document system and are suitable for configuration management (revision control). If control unit files exist, they are referenced from the system file.
Since Telelogic Tau operates on files, you may use any revision handling system for checking out work copies of your SDL diagram files to your work directory (this task needs to be performed outside Telelogic Tau).
Telelogic Tau may also be configured to manage multiple versions of your source documents, by binding a document to any suitable file in your file system.
Telelogic Tau provides mechanisms for an easy rebinding of documents. These file binding mechanisms allow you to keep track of multiple versions of your source documents with a minimum of effort.
Virtually all of the output information that is produced with Telelogic Tau consists of files, most of them use a text-based format (for instance SDL-PR files and C files).
You may specify default locations for files that are generated with Telelogic Tau. Also, you may specify the level of granularity, allowing you to generate multiple files or one file only.
Furthermore, SDT features an SDL-Make mechanism that minimizes the turnaround time, by computing the passes the tool must run in response to a modification of a source diagram.
On UNIX workstations, Telelogic Tau is implemented as X Window applications, using the Motif widget set. On PCs, Telelogic Tau is designed as Microsoft Windows applications (Windows 95 or Windows NT 4.0). At present, some features are not available on the PC platform.
Since ORCA and SDT are supported on different systems, there may be slight differences in the appearance of each tool between environments. However, the functionality is identical as long as the underlying system and the OS allow it.
All Telelogic Tau graphical applications follow the same style guide, described in User Interface and Basic Operations.
Full compatibility between ORCA and SDT on PCs and on UNIX workstations ensures that future upgrading of your computers towards workstations is possible, and allows heterogeneous network solutions with, for instance, PCs connected to a UNIX based file server.
On workstation environments, the following architectures and operating systems are supported:
For more information about the supported platforms, see System Prerequisites.