TMDL

The Project

Generating LOTOS specifications from informal timethread maps is an interesting challenge. This projects aims at automating part of the interpretation method introduced in the author's master thesis. We define a textual language (TMDL) to represent timethread maps, and a compiler that translates TMDL descriptions into LOTOS specifications (tmdl2lot). The reader is assumed to have a background on timethreads and LOTOS.

The Languages

STDL

This Single Timethread Description Language was created to represent individual timethreads as entities in their own right. Because it is defined as an EBNF grammar, STDL implicitly includes several creation rules, indicating what is a valid timethread.

TMDL

This new language's intent is to include both STDL and LARGs in one unique model. The Timethread Map Description Language is defined as a BNF grammar to which a set of external semantic rules will be attached. Issues related to TMDL are:
• Creation of a new grammar.
• Definition of constructors representing interactions (timethreads and events), and recursive groupings.
• Specification of rules indicating valid and invalid interactions.
• Inclusion of internal (hidden) and external events, therefore defining the system interface.
• Integration of STDL in TMDL.
• Keeping in mind the extensibility of the language.
• Taking in account the generality of the language (independent from LOTOS).
The TMDL grammar is available in EBNF.

N.B.: TMDL supports neither stubs/plugins nor components.

The Compiler

An automated tool would have two functionalities. The first one is a transformation based on the analysis and grouping phases of the LAEG (LOTOS Architectural Expression Generation) method defined in Bordeleau's thesis. The second functionality consists in compiling the transformed TMDL description into a LOTOS specification.

The prototype compiler is available in Sun 4 and DOS format (other platforms could be considered upon request).

Objectives

The resulting tool is a prototype and might not implement all desirable functionalities. However, the compiler prototype allows:
• A first taste of automated translation of timethread maps into LOTOS.
• To raise new issues related to the formalization of timethreads.
• To improve the interpretation method and TMDL.
• To build case studies more easily.
• To show the potential of this design method.

Functionalities

The TMDL-to-LOTOS compiler, referred as tmdl2lot from now on, takes as input a timethread map described in TMDL. It outputs three different files:



• A LOTOS specification corresponding to the timethread map. It is generated using the interpretation method explained in Amyot's thesis.
• An error file including all error and warning messages generated during the compilation process. tmdl2lot also gives a summary of the number of errors/warnings.
• The different symbol tables used during the compilation. First, the map structure is shown (interaction tree) followed by global symbol tables (timethreads, groups, tag values, internal/external activities). Then, for each timethread in the map, tmdl2lot presents the local symbol tables for internal activities, external activities, and tag identifiers. Note that some table elements possess flags that are also displayed (defined, undefined, used, unused, activity type, number of value parameters...). This file is used for debugging purpose only.

Usage

The user calls tmdl2lot in the following way:

tmdl2lot { Options }

where the possible list of Options may include:
 
 

• [-i input_file] : TMDL description file (default is standard input).
• [-o output_file]: LOTOS specification file (default is standard output).
• [-t output_file]: Symbol tables file (no file by default).
• [-e output_file]: Error and warning file (default is standard error).
• [-b buffer_size]: Size of internal buffers, in bytes (default is 8192).
• [-f] : Flag for forced output, if an error is encountered (by default, no LOTOS file is output when an error occurs).
The validity of each file is verified, and an error message is output when an unknown option is encountered.

Examples

Several examples used to test the compiler are available here:
• Traveler example (TMDL, LOTOS, Symbol table, Errors)
• Simple connection in a telephony system (TMDL, LOTOS, Symbol table, Errors)
• Testing of interactions (TMDL, LOTOS, Symbol table, Errors)
• Testing of TMDL constructs (TMDL, LOTOS, Symbol table, Errors)

Documentation

A report on the making of the compiler is available:
 
LOTOS Generation from Timethread Maps: A Language and a Tool
Daniel Amyot, University of Ottawa, September 1994.
PostScript and FrameMaker 3 formats.
 
STDL and the interpretation method are covered in Daniel Amyot's Master Thesis.

Comments

Please, report any comment or suggestion to Daniel Amyot at damyot@site.uotawa.ca