Difference between pages "D32 Code generation" and "D32 Model Animation"

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=== Overview ===
+
= Model Animation =  
  
The code generation activity has been undertaken at the University of Southampton. This has been a new line of work for DEPLOY that was not identified in the original Description of Work for the project. Development of the approach, and the tools to support, it involved a number of team members at Southampton; and also at other institutions. The code generation approach draws on our recent experience with technologies such as ''Shared Event Decomposition'' [[http://wiki.event-b.org/index.php/Event_Model_Decomposition]], and the ''EMF Framework for Event-B'' [[http://wiki.event-b.org/index.php/EMF_framework_for_Event-B]]. There was collaboration at an early stage with Newcastle University, where we explored the commonalities between their work on work-flow [[http://wiki.event-b.org/index.php/Flows]] and the algorithmic structures used in our approach. Collaboration with the University of York was also established since we chose to use their ''Epsilon'' [[http://www.eclipse.org/gmt/epsilon/]] model-to-model transformation technology.
+
== Overview ==
 +
=== Siemens Application===
 +
The most important additions of the last 12 months are:
 +
* Application of ProB in three active deployments, namely the upgrading of the Paris Metro Line 1 for driverless trains, line 4 of the S\~{a}o Paulo metro and line 9 of the Barcelona metro. We also briefly report on experiments on the models of the CDGVAL shuttle. The paper <ref>Leuschel et al. FM'2009</ref> only contained the initial San Juan case study, which was used to evaluate the potential of our approach.
 +
* In this article we describe the previous method adopted by Siemens in much more detail, as well as explaining the performance issues with Atelier B.
 +
* Comparisons and empirical evaluations with other potential approaches and alternate tools (Brama, AnimB, BZ-TT and TLC) have been conducted.
 +
* We provide more details about the ongoing validation process of ProB, which is required by Siemens for it to use ProB to replace the existing method.
  
=== Motivations ===
+
The validation also lead to the discovery of errors in the English version of the Atelier B reference manual.
 +
 +
Also, since  <ref>Leuschel et al. FM'2009</ref>, ProB itself has been further improved inspired by the application, resulting in new optimisations in the kernel (see below).
  
The decision was taken in 2009 [[http://wiki.event-b.org/index.php/D23_Code_Generation]] to include code generation as a project goal, and
+
More details:
 +
* <ref>Leuschel et al. FAC, special issue of FM'2009</ref>
 +
* <ref>Leuschel et al. Draft of Validation Report</ref>
  
 +
=== Multi-level Animation ===
 +
(ABZ'2010 & SCP journal paper)
  
 +
=== Improvements to the ProB Constraint solver and empirical evaluation ===
 +
Various industrial applications have shown the need for improved constraint-solving capabilities (see CBC Deadlock, Test-Case Generation). In order to evaluate ProB, and detect areas for improvement, we have studied to what extent classical constraint satisfaction problems can be  conveniently expressed as B predicates, and then solved by ProB. In particular, we have studied problems such as the n-Queens problem, graph colouring, graph isomorphism detection, time tabling, Sudoku, Hanoi, magic squares, Alphametic puzzles, and several more. We have then compared the performance with respect to other tools, such as the model checker TLC  for TLA+, AnimB for Event-B,  and Alloy.
 +
 
 +
The experiments show that some constraint satisfaction problems can be expressed very conveniently in B and solved very effectively with ProB. For example, TLC takes 8747 seconds (2 hours 25 minuts) to solve the 9-queens problem expressed as a logical predicate; Alloy 4.1.10 with minisat takes 0.406 seconds, ProB 1.3.3 takes 0.01 seconds. For 32 queens, ProB 1.3.3 takes 0.28 seconds, while Alloy 4.1.10 with minisat takes over 4 minutes. For some others, the performance of ProB is still sub-optimal with respect to, e.g., Alloy; we plan to overcome this shortcoming in the future. Our long term goal is that B can not only be used to as a formal method for developing safety critical software, but also as a high-level constraint  programming language.
  
This paragraph shall express the motivation for each tool extension and improvement. More precisely, it shall first indicate the state before the work, the encountered difficulties, and shall highlight the requirements (eg. those of industrial partners). Then, it shall summarize how these requirements are addressed and what are the main benefits.
+
=== Constraint-Based Deadlock Checking ===
 +
Ensuring the absence of deadlocks is important for certain applications, in particular for Bosch's Adaptive Cruise Control. We are tackling the problem of finding deadlocks via constraint solving rather than by model checking. Indeed, model checking is problematic when the out-degree is very large. In particular, quite often there can be a practically infinite number of ways to instantiate the constants of a B model. In this case, model checking will only find deadlocks for the given constants
 +
chosen.
  
=== Choices / Decisions ===
+
Idea: solve constraints of axioms, invariant together with a constraint specifying a deadlock.
  
We have focussed our efforts on supporting the generation of code for typical real-time embedded control software. To this end we have developed a multi-tasking approach similar that supported by the Ada tasking model. Individual tasks are treated as sequential programs; these are modelled by an extension to Event-B, called ''Tasking Machines''. Tasks have mutually exclusive access to state variables through the use of protected resources. The protected resources correspond to Event-B machines. For real-time control, periodic and one-shot activation is currently supported; and it is planned to support aperiodic tasks in the near future. Tasks have priorities to ensure appropriate responsiveness of the control software.
+
Required Developments:
 +
* implementation of the algorithm, with semantic relevance filtering (to be able to restrict the deadlock search to certain scenarios: in Bosch's case due to the flow plugin, one wants to restrict deadlock checking e.g. to states with the variable Counter set to 10).
 +
* Improvements to ProB's constraint solving engine: (reification of constraints, more precise information propagation for membership constraints, performance improvments in the typchecker and other parts of the kernel)
  
For the DEPLOY pilots, it was regarded as sufficient to support construction of programs with a fixed number of tasks and a fixed number of shared variables – no dynamic creation of processes or objects has been accommodated. In the past year our goal has been to provide an approach, and tool support, to act as a proof-of-concept. We also gained much practical experience with the development of a code generation framework.
+
Success: Model 1 and Model 2: CrCtrl_Comb2Final;
 +
relevance of Counter=10 due to flow
  
=== Available Documentation ===
+
Deadlock Freedom PO: 34 pages of ASCII, could not be loaded in Rodin "Java Heap Space Error". Counter examples found for 8 versions in 1-18 seconds.
  
This paragraph shall give pointers to the available wiki pages or related publications. This documentation may contain:
+
=== BMotionStudio for Industrial Models ===
  
    * Requirements.
+
Previously, we presented BMotion Studio, a visual editor which enables the developer of a formal model to set-up easily a domain specific visualization for discussing it with the domain expert. However, BMotion Studio had not yet reached the status of an Industrial strength tool due to the lack of important features known from modern editors.
    * Pre-studies (states of the art, proposals, discussions).
 
    * Technical details (specifications).
 
    * Teaching materials (tutorials).
 
    * User's guides.  
 
  
A distinction shall be made on the one hand between these different categories, and on the other hand between documentation written for developers and documentation written for end-users.
+
In this work we present the improvements to BMotion Studio mainly aimed at upgrading it to an industrial strength tool and to show that we can apply the benefits of BMotion Studio for visualizing more complex models which are on the level of industrial applications. In order to reach this level the contribution of this work consists of three parts:
  
=== Planning ===
+
* We added a lot of new features to the graphical editor known from modern editors like: Copy-paste support, undo-redo support, rulers, guides and error reporting. One step towards was the redesign of the graphical editor with GEF.
 +
* Since extensibility is a very important design principle for reaching the level of an industrial strength tool we pointed up the extensibility options of BMotion Studio.
 +
* We introduced the visualization for two models which are on the level of industrial applications in order to demonstrate that we can apply the benefits of BMotion Studio for visualizing more complex models. The first model is a mechanical press controller and the second model is a train system which manages the crossing of trains in a certain track network.
  
This paragraph shall give a timeline and current status (as of 28 Jan 2011).
+
=== Various other improvements ===
 +
 
 +
mainly inspired by Siemens and Bosch Applications
 +
 
 +
Improved AVL algorithms, more operators
 +
 
 +
record support, treatment of infinite sets,
 +
 
 +
== Motivations ==
 +
 
 +
The above works were motivated mainly to support the following three industrial deployments:
 +
* Siemens: enable Siemens to use ProB in their SIL4 development chain, replacing Atelier B for data validation.
 +
* Bosch: provide animation and constraint-based deadlock detection for the Adaptive Cruise Control
 +
* SAP: provide a way to generate test cases using constraint-based animation
 +
 
 +
== Available Documentation ==
 +
 
 +
=== References ===
 +
<references/>
 +
 
 +
== Planning ==
 +
 
 +
* Finish Validation Report
 +
* Write up Constraint-Based Deadlock Checking and integrate fully into Rodin Platform
 +
* Support mathematical extensions in ProB

Revision as of 09:44, 29 November 2010

Model Animation

Overview

Siemens Application

The most important additions of the last 12 months are:

  • Application of ProB in three active deployments, namely the upgrading of the Paris Metro Line 1 for driverless trains, line 4 of the S\~{a}o Paulo metro and line 9 of the Barcelona metro. We also briefly report on experiments on the models of the CDGVAL shuttle. The paper [1] only contained the initial San Juan case study, which was used to evaluate the potential of our approach.
  • In this article we describe the previous method adopted by Siemens in much more detail, as well as explaining the performance issues with Atelier B.
  • Comparisons and empirical evaluations with other potential approaches and alternate tools (Brama, AnimB, BZ-TT and TLC) have been conducted.
  • We provide more details about the ongoing validation process of ProB, which is required by Siemens for it to use ProB to replace the existing method.
The validation also lead to the discovery of errors in the English version of the Atelier B reference manual.

Also, since [2], ProB itself has been further improved inspired by the application, resulting in new optimisations in the kernel (see below).

More details:

Multi-level Animation

(ABZ'2010 & SCP journal paper)

Improvements to the ProB Constraint solver and empirical evaluation

Various industrial applications have shown the need for improved constraint-solving capabilities (see CBC Deadlock, Test-Case Generation). In order to evaluate ProB, and detect areas for improvement, we have studied to what extent classical constraint satisfaction problems can be conveniently expressed as B predicates, and then solved by ProB. In particular, we have studied problems such as the n-Queens problem, graph colouring, graph isomorphism detection, time tabling, Sudoku, Hanoi, magic squares, Alphametic puzzles, and several more. We have then compared the performance with respect to other tools, such as the model checker TLC for TLA+, AnimB for Event-B, and Alloy.

The experiments show that some constraint satisfaction problems can be expressed very conveniently in B and solved very effectively with ProB. For example, TLC takes 8747 seconds (2 hours 25 minuts) to solve the 9-queens problem expressed as a logical predicate; Alloy 4.1.10 with minisat takes 0.406 seconds, ProB 1.3.3 takes 0.01 seconds. For 32 queens, ProB 1.3.3 takes 0.28 seconds, while Alloy 4.1.10 with minisat takes over 4 minutes. For some others, the performance of ProB is still sub-optimal with respect to, e.g., Alloy; we plan to overcome this shortcoming in the future. Our long term goal is that B can not only be used to as a formal method for developing safety critical software, but also as a high-level constraint programming language.

Constraint-Based Deadlock Checking

Ensuring the absence of deadlocks is important for certain applications, in particular for Bosch's Adaptive Cruise Control. We are tackling the problem of finding deadlocks via constraint solving rather than by model checking. Indeed, model checking is problematic when the out-degree is very large. In particular, quite often there can be a practically infinite number of ways to instantiate the constants of a B model. In this case, model checking will only find deadlocks for the given constants chosen.

Idea: solve constraints of axioms, invariant together with a constraint specifying a deadlock.

Required Developments:

  • implementation of the algorithm, with semantic relevance filtering (to be able to restrict the deadlock search to certain scenarios: in Bosch's case due to the flow plugin, one wants to restrict deadlock checking e.g. to states with the variable Counter set to 10).
  • Improvements to ProB's constraint solving engine: (reification of constraints, more precise information propagation for membership constraints, performance improvments in the typchecker and other parts of the kernel)

Success: Model 1 and Model 2: CrCtrl_Comb2Final; relevance of Counter=10 due to flow

Deadlock Freedom PO: 34 pages of ASCII, could not be loaded in Rodin "Java Heap Space Error". Counter examples found for 8 versions in 1-18 seconds.

BMotionStudio for Industrial Models

Previously, we presented BMotion Studio, a visual editor which enables the developer of a formal model to set-up easily a domain specific visualization for discussing it with the domain expert. However, BMotion Studio had not yet reached the status of an Industrial strength tool due to the lack of important features known from modern editors.

In this work we present the improvements to BMotion Studio mainly aimed at upgrading it to an industrial strength tool and to show that we can apply the benefits of BMotion Studio for visualizing more complex models which are on the level of industrial applications. In order to reach this level the contribution of this work consists of three parts:

  • We added a lot of new features to the graphical editor known from modern editors like: Copy-paste support, undo-redo support, rulers, guides and error reporting. One step towards was the redesign of the graphical editor with GEF.
  • Since extensibility is a very important design principle for reaching the level of an industrial strength tool we pointed up the extensibility options of BMotion Studio.
  • We introduced the visualization for two models which are on the level of industrial applications in order to demonstrate that we can apply the benefits of BMotion Studio for visualizing more complex models. The first model is a mechanical press controller and the second model is a train system which manages the crossing of trains in a certain track network.

Various other improvements

mainly inspired by Siemens and Bosch Applications

Improved AVL algorithms, more operators

record support, treatment of infinite sets,

Motivations

The above works were motivated mainly to support the following three industrial deployments:

  • Siemens: enable Siemens to use ProB in their SIL4 development chain, replacing Atelier B for data validation.
  • Bosch: provide animation and constraint-based deadlock detection for the Adaptive Cruise Control
  • SAP: provide a way to generate test cases using constraint-based animation

Available Documentation

References

  1. Leuschel et al. FM'2009
  2. Leuschel et al. FM'2009
  3. Leuschel et al. FAC, special issue of FM'2009
  4. Leuschel et al. Draft of Validation Report

Planning

  • Finish Validation Report
  • Write up Constraint-Based Deadlock Checking and integrate fully into Rodin Platform
  • Support mathematical extensions in ProB