Train Control Language
Teaching Computers Interlocking
By: J. Endresen, E. Carlson, T. Moen1, K. J. Alme, Haugen, G.
K. Olsen & A. Svendsen
Synthesizing Software Models
Generate Train Station Models Automatically
By: Andreas Svendsen, Øystein Haugen, and Birger MøllerPedersen
Presenter: Rahma Al Mahruqi
CISC 836
Train Control Language
Teaching Computers Interlocking
Outline
• Motivation
• Objectives
• Computer Based Interlocking CBI
• Domain Specific Modeling Language DSL
• Syntax of TCL
• TCL Semantics
• Advantages of TCL
Motivation
Bridging the gap between trains and computers
with a specially designed language that enables
the signaling experts to create consistent train
interlocking systems.
Objectives
• ABB and SINTEF organizations have developed TCL for specifying and
automating the train interlocking systems.
• Combine the station drawing with the train routes and interlocking
tables in the TCL.
• Generate automatically the programmable logic controller PLC code
and test cases from the models created in the TCL language.
• Describes DSL for specifying stations and to allow automatic
generation of interlocking tables and the code for the Computer
Based Interlocking CBI
Terminologies
• DSL : Domain Specific Language
• DSM Domain Specific Modeling
• TCL : Train Control Language
• PLC: Program Language Controller
• CBI : Computer Based Interlocking
• EMF: Eclipse Modeling Framework
• GMF : Graphical Modeling Framework
Introduction
• Interlocking system controls the basic elements of the train station
such as signals, switches, truck circuits and allocate train routes to
avoid collisions.
• Interlocking system ensures that the route is safe by reading the
status of the elements in the route (e.g. tracks, switches, signals) to
see if they comply with the logic of the interlocking system.
Interlocking System
• Prevents dangerous train movement on a train station by
giving a “clear” signal to a train only if the requested
route is safe.
Interlocking System
• Development of interlocking source code is a time-consuming
process requiring a large amount of resources.
• The logic is illustrated by an interlocking table, and realized by the
interlocking source code, in the form of functional blocks of code
that are executed by the PLCs in their control of the station.
CBI Development Workflow
Domain Specific Language
• DSL is a modeling language dedicated to a particular problem
domain.
• Bridge between the experts of an application domain and the
experts of computer science.
Train Control Language
• DSL done through a metamodel, which automates the production of
source code for computers controlling train stations
• Improves the completeness and consistency of the specifications
and reduce the human effort.
• Applies UML class diagrams to define metamodels.
Metamodel
• Model of the language which defines the language concepts
and the relations between these concepts.
• Characteristics of a Metamodel:
- Composition (Stations contain TrackCircuits etc.),
- Attributes (Station has a name) and
- Relations (TrainRoute refers to a number of
TrackCircuits).
A small piece of the TCL Metamodel
Track Inheritance Hierarchy.
Concrete Syntax of TCL
• Open source Eclipse and its modeling framework EMF
technology used to define TCL.
• Graphical Modeling Framework GMF used to define the
graphics of the terms of the metamodel.
• GMF technology helps produce an editor for TCL based on the
metamodel and the graphic definitions.
• The editor is embedded into the eclipse environment.
The Semantics of TCL
Advantages of TCL
• Provides a clear interface between the realms of computer science
and signaling.
• Makes the signaling experts capable of creating advanced computer
systems without knowing the details of computer programming.
• Provides automatic generation of several different artifacts
previously manually developed.
• Much of the tedious and error-prone manual controls can be
eliminated and the highly competent signaling experts can instead
be used to refine the designs through the TCL language.
Conclusion
• TCL can improve the development process of interlocking systems.
• Signaling experts will be able to design the systems directly.
• The interlocking systems will be generated directly from the graphic
representation which is produced for validation and tests.
• The traditional manual work will be eliminated or minimized.
Synthesizing Software Models
Generate Train Station Models Automatically
Motivation
• Presents an approach for automatic synthesis of software models
which are increasingly being used for representing software
applications at a high abstraction level.
• Model analysis is useful for performing model-based testing which
involves generating test-cases for the application.
• Software applications can be produced quicker and more reliable by
automating the task of building models
• A number of software models can be created to validate and verify
a code generator.
Objectives
• Description of an approach for synthesizing software models
automatically based on a formal definition of the DSL and userdefined properties.
• Illustrate real example from the train domain TCL, where train
station models are generated automatically.
Terminologies
• DSL is defined by an abstract syntax, a concrete syntax
and well-defined semantics.
• Accompanied by code-generators and frameworks.
• TCL is a graphical DSL for modeling train stations and
generate configuration code for a framework which
controls train station signaling systems.
• Alloy is a formal language used to find and produce
intended DSL models.
TCL Metamodel
TCL concrete syntax
TCL Model Components
• Repository model, containing the abstract syntax,
• Diagram model storing the location of each element on the canvas.
• Includes algorithms for calculating the diagram model based on the
repository model.
• This allows the graphical diagram model to be reconstructed if the
repository model is exposed to changes.
TCL Graphical Editor
Alloy
• Light-weight declarative language using relational calculus for
modeling a system formally .
• Formal validation and verification of a system using mathematical
notation to express the system precisely, to prove its correctness.
• Supplied with an analyzer tool based on first-order-logic performs
automatic analysis of Alloy models.
How Alloy works
• Alloy Analyzer only performs analysis within a user-specified
scope, restricting the number of elements of each type in the
model
• When the Alloy Analyzer searches for a solution, it populates
all signatures in the model with model elements up to the
user-specified scope.
• An Alloy model typically consists of signatures, fields, facts,
predicates and assertions.
Model Synthesis
Generate models automatically based on specifications, for:
• Reducing development time of models by generating a basis which
can be extended.
• Modeling large sets of models to reduce time-consuming.
• Generate a model that is close to the target application model.
Synthesizing TCL Model
• Generating TCL Models
• Adding Dynamic Properties
• Optimizing Alloy Models
Synthesizing TCL Model
Generating TCL Models
TCL Generated Stations- Static Properties
TCL with Dynamic Properties
• Dynamic properties is defined as a quality that can only be
determined by dynamic analysis, such as model simulation.
• Using dynamic analysis, certain properties of the model can be
checked or simulated before the model is generate, eg. The
number of tracks of the station can give an indication of how
many trains the station can handle simultaneously.
Optimizing Alloy Models
• The Alloy Analyzer performs complete analysis within the userspecified scope. Complete analysis involves populating all possible
models and discarding the ones where the constraints (facts) do not
hold. Therefore,
• When the scope increases, the number of possible combinations to
form solution models, and thus the analysis time, increases
exponentially.
Conclusion
• Generate application models automatically based on a well defined
specification of a DSL.
• Use Alloy to define the semantics of the DSL and illustrated the
approach using TCL.
• Alloy is used because of its uniform notation and its automatic
analyzer.
• Using Alloy as a specification language provides the possibility to
specify the operational semantics of DSL .
Conclusion
• Performing model synthesis reduce the cost of developing
applications, and several applications can be generated to test a
code generator.
• Thorough knowledge of Alloy as specification language and TCL is
required to apply the proposed approach.
Critique
Advantages:
• Well organized paper
• Lot of figures
• Good references
Limitations:
• Approach with limit to 3 track station only- generate large set of
station using dynamic approach
• Perform case studies and implementing the approach with other
DSL