Difference between pages "Documentation Overhaul DoW" and "Tasking Event-B Tutorial"

From Event-B
(Difference between pages)
Jump to navigationJump to search
imported>Jastram
 
imported>Andy
 
Line 1: Line 1:
== Status ==
+
For more information contact Andy Edmunds - University of Southampton - mailto:ae2@ecs.soton.ac.uk
 +
=== Tasking Event-B Tutorial Overview ===
  
This project is currently in the second iteration, which is scheduled to end on October 8th 2011.  The continuous build of the handbook can be found at http://handbook.event-b.org/
+
<span style="color: RED">'''Caution''': This Page is under Construction - some parts are incomplete</span>
  
'''NOTE:''' "mh" means man-hours
+
This tutorial follows on from the abstract development described [http://wiki.event-b.org/index.php/Development_of_a_Heating_Controller_System here].
  
== Representatives of Stakeholders ==
+
This code generation tutorial extends the Heating Controller tutorial example, and makes use of example projects from the download site. The code generation stage produces implementable Ada code, and also an Event-B model. It is a model of the implementation, and contains flow control variables that model the flow of execution through the task body. The Ada code is produced from an intermediate model that is not visible to the user. The Common Language model (CLM), is generated from the Tasking Event-B by a translation tool. Ada (and other implementations) may be generated from the CLM. An overview of Tasking Event-B can be found [http://wiki.event-b.org/index.php/Tasking_Event-B_Overview here].
  
We need volunteers willing to represent the stakeholdersSo far we have:
+
In the example so far, the Heating Controller has been refined to the point where we wish to add implementation constructs. The Event-B language is not expressive enough to fully describe the implementation. Tasking Event-B facilitates this final step to implementation, by extending Event-B with the necessary constructs. Event-B machines modelling tasks, shared objects and the environment are identified, and extended with the appropriate implementation details.
  
* '''Cliff Jones''' - representing the contracting body (Deploy)
+
The example/tutorial projects are are available in the [http://deploy-eprints.ecs.soton.ac.uk/304/ e-prints archive], or on [https://codegenerationd.svn.sourceforge.net/svnroot/codegenerationd/Examples/Heating_ControllerTutorial_v0.2.0/ SVN].
* '''Rainer Gmehlich''' - representing an industrial partner (Bosch)
 
* '''Andreas Roth''' - representing an industrial partner (SAP)
 
* '''Aryldo G Russo Jr''' - representing an associate (AES)
 
* '''Carine Pascal''' - representing Systerel
 
* '''Lukas Ladenberger''' - representing an academic partner (UDUS)
 
* '''Matthias Schmalz''' - representing an academic partner (ETHZ)
 
  
The task of the reviewers is to provide feedback in a timely manner.
+
{| border="1"
 +
|Heating_ControllerTutorial2_Completed
 +
|An example project with an environment simulation. The environment variables are monitored and controlled using subroutine calls. The project contains a complete Tasking Development with generated Event-B and Ada code.
 +
|-
 +
|Heating_ControllerTutorial2_Partial1
 +
|A project with the final decomposition completed, ready to begin Tasking Event-B Development.
 +
|-
 +
|Heating_ControllerTutorial2_Partial2
 +
|A partially completed tasking specification for the continuation of the tutorial.
 +
|-
 +
|TheoriesForCG
 +
|Contains the mathematical language translations; encoded as rules in a theory plug-in rule-base.
 +
|}
  
== First Iteration ==
+
== Using the Tasking Extension ==
 +
The steps needed to generate code from an Event-B model, in this tutorial, are as follows,
 +
* Step 1 - [[Tasking Event-B_Tutorial#Adding the Implementation Level Refinement|Adding the Implementation Level Refinement]]
 +
* Step 2 - [[Tasking Event-B_Tutorial#Pre-processing|Pre-processing]]
 +
* Step 3 - [[Tasking Event-B_Tutorial#Providing the Annotations for Implementations|Add Tasking annotations]].
 +
* Step 4 - [[Tasking Event-B_Tutorial#Invoking the Translation|Invoke translators]].
 +
=== Download and Copy the Theories ===
 +
The translations of the Event-B mathematical language to the target language constructs are specified as rules in the theory plug-in. Two rule files are included for the example, and are available in the [https://codegenerationd.svn.sourceforge.net/svnroot/codegenerationd/Examples/Heating_ControllerTutorial_v0.2.0/ SVN]. The files can be downloaded and copied into an Event-B project called ''MathExtensions''. The theory must then be deployed. Right-Click on the theory file and select deploy to do this. The non-Event-B project, the original download may now be deleted.
  
=== WP1-1: Styles Guides and Templates (16mh) ===
+
=== Adding the Implementation Level Refinement ===
 +
The final decomposition generates the machines that are required for code generation. However, it is not possible to edit the machines since they are machine generated, and therefore this is prohibited. In order to be able to modify the models we will refine the generated machines. This is where we begin with the ''Heating_ControllerTutorial2_Partial1'' project. To refine the machines we can use the automatic refinement feature, but this presents us with two problems that are dealt with in the pre-processing step. It is also at this stage that any remaining non-deterministic constructs should be removed by replacing them with deterministic constructs.
  
Once we decide on the form for the documentation, we will create a style guide to ensure consistency.  We will also provide templates as needed, to simplify the creation of the documentation.
+
TIP: Non-deterministic constructs cause strange characters to appear in the source code. If you see strange characters in the generated code, check for non-deterministic constructs in the implementation level machines.
  
'''Deliverable:''' [http://handbook.event-b.org/review-1/html/sect0006.html A Guideline for content creators] and templates to go with it.
+
Alter_Temperature_Sensor1 in Envir1Impl: action becomes ts1 := ts1 + 1
 +
Alter_Temperature_Sensor2 in Envir1Impl: action becomes ts1 := ts1 + 1
 +
Alter_Heater_Status in Envir1Impl: action becomes hss := FALSE
 +
INITIALISATION in Heater_Monitor_TaskImpl: becomes shs := FALSE
  
=== WP1-2: Wiki Migration or Version Plan (4mh) ===
+
We also need to add a typing flag to an invariant. We need to add it in only one place, and this is where an invariant is used type a variable, in the Heating Controller machine. The flag is used to guide the translator to the typing invariant. This is because there is more than one invariant involving that particular variable. They may also be added to guards where parameters are typed in guards, and the parameters are referred to in more than one guard.
  
Content must be accessible at all times. However, we will either migrate or restructure data significantly.  We need a plan describing the approach.
+
* Go to the ''Heater_Monitor_TaskImpl typing_shs'' invariant.
 +
* Add the typing flag, by right-clicking on the invariant and selecting typing from the menu.
  
'''Deliverable:''' A Guideline for content migration: [[Handbook Content Migration]]
+
=== Pre-processing ===
  
=== WP1-3: Reference Section  (20mh) ===
+
The pre-processing step should be a temporary, the solutions can be incorporated into the tool to automatically perform the changes that are required.
  
The Reference Section will be the most comprehensive part of the documentation.  It will consist of a number of chapters.  At this point we see at least the following sections:
+
* The Code Generator requires a flattened version of each machine; all of the Event-B elements should be available in the implementation level machine.
* Event-B Reference
+
* Composed machines are not currently able to be refined, so anything that requires synchronization of events requires some manual updates.
* Mathematical Notation Reference
 
* Modeling Language Reference
 
* Proof Tactics
 
* GUI Elements
 
* Glossary
 
  
There may be more.  We must have a good understanding of the content we intend to cover.  Otherwise we won't be able to allocate our resources wisely.
+
===== 'Flattening' the Implementation Machines =====
  
The FAQ will grow naturally and won't need a detailed plan beforehand.
+
The temporary solution for flattening:
 +
* Make events ''not extended''.
 +
* Copy missing invariants.
  
'''Deliverable:''' The [http://handbook.event-b.org/review-1/html/sect0031.html table of contents of the reference section] (1st and maybe 2nd level)
+
I found the Event-B Machine Editor's synthesis view useful for this. Invariants can be copy-pasted into the implementation machine from the abstraction. (A dummy invariant can be added and selected for pasting)
  
=== WP1-4: Tutorial outline (20mh) ===
+
===== Providing the correct Composed Machine =====
  
The tutorial is most likely the first thing new users are being confronted with. Thus, we feel that this chapter requires a lot of diligence.  Also, we will perform user tests with the tutorial, once created.
+
The composed machine problem is sub-divided into two sub-problems. Firstly composed machines cannot be refined, and secondly when a machine is further decomposed there is no link between the first composed machine and the newly generated composed machine. So one or both of these problems may occur, depending on the number of decompositions.
The tutorial will guide the user through installation, ensure that the mathematical background exists, introduce the GUI and guide the user through a few modeling sessions.
 
  
We feel that the current tutorial overwhelms the user by focusing on too many aspects at the same time.  For instance, we believe that the first model must allow all proofs to be discharged automatically.
+
We must manually add the information to the composed machines to address these two problems.
  
'''Deliverable:''' [http://handbook.event-b.org/review-1/html/tutorial.html The table of contents of the tutorial, including the description of the individual sections].
+
The temporary solution for composed machines:
 +
* Modify the lowest level decomposed machine, HCtrl_M1_cmp, to ''include'' the implementation level machines (task names ending in *Impl). To do this,
 +
* open the composed machine editor. Open the INCLUDES edit feature.
 +
* Select the second drop-down box and find the *Impl version of each machine.
 +
* Save the composed machine.
 +
* Now add missing synchronizations to the composed machine. Add the ''Envir1Impl'' to the includes of HCtrl_M1_cmp.
 +
* Each composed event in the task, that synchronizes with the Environ machine, must have the remote event synchronization added manually. This can only be done by inspection of each composed event. We need to update Sense_Temperatures, Display_Current_Temperature, Actuate_OverHeat_Alram, Actuate_Heat_Source, Sense_Heater_Status, Actuate_NoHeat_Alarm, Sense_PressIncrease_Target_Temperature, Sense_PressDecrease_Target_Temperature, Display_Target_Temperature. One by one, expand the events in the composed events section of the composed machine editor; add a new event in the combines events section, select ''Envir1Impl'' and add the synchronizing event from the list-box to the right.
  
=== WP1-5: First iteration on Tutorial (80mh) ===
+
=== Adding Tasking Event-B ===
 +
Each Machine should be completed as follows.
 +
==== The Temp_Ctrl_TaskImpl Machine ====
 +
Continuing with the tutorial project ''Heating_ControllerTutorial2_Partial2'', we need to make changes to the following machines. During the tutorial we will cut and paste from ''Heating_ControllerTutorial2_Completed'' model when, specifying the task bodies, to save typing.
  
Our goal is to use the remaining time of the first iteration to make the tutorial rudimentary complete.  This means that all examples are worked out and that most of the copy stands.  There may be gaps, but only if the gaps don't impair the usefulness of the tutorial (e.g. the section on the mathematical notation may refer to the Abrial-Slides).
+
*Add the ''Auto Task'' extension.
 +
**Right-Click on the Machine node in the Rose tree-editor,
 +
**and click on ''New Child Element/Auto Task Machine'' menu option.
  
We expect that during this work, the rest of the documentation will start to fill up with placeholders (e.g. empty entries in the reference section.
+
''Auto Tasks'' are tasks that will be declared and defined in the ''Main'' procedure of the implementation. The effect of this is that the ''Auto Tasks'' are created when the program first loads, and then activated (made ready to run) before the ''Main'' procedure body runs.  
  
'''Deliverable:''' [http://handbook.event-b.org/review-1/html/tutorial.html The roughly completed Tutorial].
+
*'''Edit the TaskBody'''.
 +
**Open the properties editor for the task body.
 +
**Copy and paste the task body from ''Heating_ControllerTutorial2_Completed/Temp_Ctrl_TaskImpl''
 +
**Set the task type to ''Periodic'',
 +
**Set a period of 250 milliseconds.  
 +
**Click on the Set Task Body button.
  
=== WP1-6: Iteration Review (20mh) ===
+
The task body is parsed, and if successful will add the structure to the EMF tree. If parsing is not successful an error panel will display the source of the error.
  
In addition to discussion the results so far, we will decide on the details of WP2-1.
+
We now look at the sensing event ''Sense_Temperatures'' event in ''Temp_Ctrl_TaskImpl''. In order to assist with the translation we add the following annotation:
  
== Second Iteration ==
+
*'''Add a Sensed Event Annotation'''.
 +
** Right-click on the ''Sense_Temperatures'' Event node.
 +
** Select ''New Child/Implementation'' from the menu.
 +
** Go to the Implementation properties view and set the ''Implementation Type'' property to ''Sensing''.
  
=== WP2-1: Migration and Creation of entries in the Reference Section (60mh) ===
+
We now look at the actuating event ''Display_Current_Temperatures'' event in ''Temp_Ctrl_TaskImpl''. In order to assist with the translation we add the following annotation:
  
We will start filling the reference section. We expect a number of sections to be quite labor-intensive, especially if it involves creating many screenshots.
+
*'''Add an Actuating Event Annotation'''.
 +
** Right-click on the ''Display_Current_Temperatures'' Event node.
 +
** Select ''New Child/Implementation'' from the menu.
 +
** Go to the Implementation properties view and set the ''Implementation Type'' property to ''Actuating''.
  
'''Deliverable:''' [http://handbook.event-b.org/review-2/html/reference.html Completed Parts of the Reference Section].
+
==== The Shared Machine ====
  
=== WP2-2: Copy Editing of existing content (60mh) ===
+
The next step is to identify the ''Shared_ObjectImpl'' machine as a ''Shared Machine''.
 +
* Right-click on the ''Shared_Object'' Machine node in the Rose tree-editor.
 +
* Select ''New Child/Shared Machine'' from the menu.
  
We managed to recruit Joy Clark, a native English speaking student, who will from this iteration on perform copy editing.  In this iteration, she will make one complete run through the tutorial to improve copy and to identify gaps, which will then be filled.
+
==== The Environ Machine ====
 +
In the prepared machine we identify the ''Envir1Impl'' as an ''Environ Machine'',
  
'''Deliverable:''' [http://handbook.event-b.org/review-2/html/ Copy-edited content].
+
*Add the ''Environ Machine'' extension.  
 +
**Right-click on the Machine node in the Rose tree-editor.
 +
**Select the ''New Child Element/Auto Task Machine'' menu option.
  
=== WP2-3: Guideline for Plugin Developers (20mh) ===
+
In the implementation, ''Environ Tasks'' are declared and defined in the ''Main'' procedure . The ''Envir1Impl'' machine models a task that simulates the environment, and can be used to generate simulation code. For deployment in a non-simulated environment the environ machine's generated code can be ignored. To specify the Environment task's behaviour we add edit the task body.
  
Even though Plugins are officially not covered by the handbook, there are many places where covering some aspects would be extremely useful. We will produce a guideline for Plugin developers for including references to their work in the handbook.
+
*'''Edit the TaskBody'''.
 +
**Open the properties editor for the task body.
 +
**Copy and paste the task body from ''Heating_ControllerTutorial2_Completed/Envir1Impl''
 +
**Set the task type to ''Periodic'',
 +
**Set a period of 100 milliseconds.
 +
**Click on the Set Task Body button.
  
'''Deliverable:''' [http://rodin-b-sharp.svn.sourceforge.net/viewvc/rodin-b-sharp/trunk/Handbook/org.rodinp.handbook.feature/latex/style-guide.tex?revision=13198&view=markup The Guideline].
+
When clicking on Set Task Body, the task body text is sent to the parser. If parsing is successful then a builder adds the structure to the EMF tree. If parsing fails then an error panel displays the source of the error.
  
=== WP2-4: Iteration Review (20mh) ===
+
The final step is to complete the ''Sense_Temperatures'' event. The event, being a kind of synchronization, synchronizes with the ''Sense_Temperatures'' event in the ''Temp_Ctrl_Task'' tasking machine. We annotate the model with sensing and actuating implementation types.
  
The results will be evaluated, particularly on whether the tutorial needs more focus or not.
+
*'''Add a Sensed Event Annotation'''.
 +
** Right-click on the ''Sense_Temperatures'' Event node.
 +
** Select ''New Child/Implementation'' from the menu.
 +
** Go to the Implementation properties view and set the ''Implementation Type'' property to ''Sensing''.
  
== Third Iteration ==
+
*'''Add an Actuating Event Annotation'''.
 +
** Right-click on the ''Display_Current_Temperatures'' Event node.
 +
** Select ''New Child/Implementation'' from the menu.
 +
** Go to the Implementation properties view and set the ''Implementation Type'' property to ''Actuating''.
  
=== WP3-1: Completion of the Reference Section (30h) ===
+
=== A Summary of Steps ===
 +
For a Tasking Machine definition:
 +
# Add the Tasking Machine type (Auto etc).
 +
# Set the task type (Periodic etc.).
 +
# Set the task priority.
 +
# Specify the task body.
 +
# For sensing/actuating events, add the Event Type.
  
The goal is to fill in all blanks in the reference section at this point.  We may keep a list of entries that need improvements.
+
For a Shared Machine definition:
 +
# Add the ''SharedMachine'' Machine type.
  
'''Deliverable:''' [http://handbook.event-b.org/review-3/html/reference.html Complete Reference Section].
+
For an Environ Machine definition:
 +
# Make the type an Environ Machine type.
 +
# Set the task type Periodic; a shorter period than the shortest task period is best for simulation.
 +
# Set the task priority.
 +
# Specify the task body, it will contain a simulation of changes in the environment.
 +
# For each sensing/actuating event, add the Event Type.
  
=== WP3-2: User Tests of Tutorial (40mh) ===
+
== Invoking the Translators ==
  
We will offer a B block course in fall 2011 in Düsseldorf, where the students will learn classical B (not Event-B).  They will get a class project in Event-B. They will have to teach themselves Event-B using the tutorial, in order to solve their assignment. We will monitor the progress, collect feedback and identify overall weaknesses in the tutorial. We expect a group of 5-10 students.
+
* To generate Ada code,
 +
** Right-Click on the composed machine, or any tasking machine in the development, select ''Code Generation/Translate Event-B to Ada''.
 +
** Open the generated ''code'' directory in the project to view the source files. A refresh will be necessary to make the code visible. The .gpr file has been provided for AdaCore GPS users.
  
'''Deliverable:''' [http://handbook.event-b.org/review-3/2011_12_08_Handbook_Survey.pdf Results of the user tests]
+
* To create the Event-B model of the implementation,
 +
** Right-Click on the composed machine, or any tasking machine in the development, select ''Code Generation/Translate Tasking Event-B to Event-B''.
 +
** The Event-B model should be updated with the flow control variables. Users are not able to manually edit the generated elements. The additions can be removed using the menu option ''Code Generation/Remove Generated Event-B''
  
=== WP3-3: Completion of the Tutorial (20mh) ===
+
=== Generated Code ===  
 
+
Generated code should be visible in the code directory, in the Event-B project. You can see the directory in the resource view; or alternatively, click on the view menu in the Event-B perspective, select customize view, and uncheck the ''all file and folders'' filter.
We will incorporate the feedback from the review.
+
[[Category:User documentation]]
 
 
'''Deliverable:''' [http://handbook.event-b.org/review-3/html/tutorial.html Complete Tutorial].
 
 
 
=== WP3-4: Provide context to give the documentation a whole appearance (20mh) ===
 
 
 
At this point, we will pay attention to the document “as a whole”.  We will make sure all sections have proper introductions, check the style, etc.  We will also create a list of sections that need particular attention.
 
 
 
'''Deliverable:''' [http://handbook.event-b.org/review-3/html/ Improved documentation]
 
 
 
=== WP3-5: Remove migrated content from Wiki (20h) ===
 
 
 
Eventually, we want to remove migrated content from the Wiki to prevent outdated information.  At the same time, we will create a tighter integration between handbook web site and the Rodin Wiki.  We'll also visit every single wiki page and if there is ambiguity on where the content should reside, we'll track down the owner and figure it out.
 
 
 
'''Deliverable:''' [http://wiki.event-b.org/ Cleaned-up Wiki].
 
 
 
=== WP3-6: Creation of an index (10mh) ===
 
 
 
An index will be created, for two reasons: First, in the print version, this will be a useful tool in addition to cross references and the table of contents.  Second, it will allow the location of topics where the search functionality is simply inadequate (e.g. mathematical symbols, words like "where").
 
 
 
'''Deliverable:''' [http://handbook.event-b.org/review-3/html/sect0037.html Index].
 
 
 
=== WP3-7: Iteration Review (20mh) ===
 
 
 
The last iteration will be used for “polishing” In this review, we allocate the resources as needed.
 
 
 
== Forth Iteration ==
 
 
 
=== WP4-1: Improve Tutorial Chapters 2.9 and 2.10 (20h) ===
 
 
 
These chapters concern the celebrity problem and location access controller, and are not as well developed as the rest of the tutorial.
 
 
 
'''Deliverable:''' Improved Chapters 2.9 and 2.19.
 
 
 
=== WP4-2: Completion of the Reference Section (20h) ===
 
 
 
There are still some open tasks in the reference section.
 
 
 
'''Deliverable:''' Complete Reference Section.
 
 
 
=== WP4-3: References and "Further Reading" Sections in Tutorial (30h) ===
 
 
 
We need a tighter integration between tutorial and reference section.  We will achieve this by providing more references into the reference section, and by providing a "Further Reading" section that points to the reference section and possibly to literature.
 
 
 
'''Deliverable:''' New subsections in each section of the tutorial, more references.
 
 
 
=== WP4-4: Coordination with Systerel to make the Rodin Handbook part of the Distribution (20h) ===
 
 
 
Currently, the handbook has to be installed manually into Rodin.  We will coordinate with Systerel to make sure that the next version of Rodin will ship with the handbook already installed.  We also plan to do some minor modifications on our build infrastructure.
 
 
 
'''Deliverable:''' Rodin with Handbook.
 
 
 
=== WP4-5: Polishing (40h) ===
 
 
 
Some screenshots and images still have to be improved, and general improvement of the text flow.  Also, we will keep collecting and processing feedback from users.
 
 
 
'''Deliverable:''' Complete Documentation.
 
 
 
=== WP4-6: Final Review (30mh) ===
 
 
 
In addition to reviewing the last iteration, we will record feedback on the project as a whole.
 

Revision as of 09:46, 2 December 2011

For more information contact Andy Edmunds - University of Southampton - mailto:ae2@ecs.soton.ac.uk

Tasking Event-B Tutorial Overview

Caution: This Page is under Construction - some parts are incomplete

This tutorial follows on from the abstract development described here.

This code generation tutorial extends the Heating Controller tutorial example, and makes use of example projects from the download site. The code generation stage produces implementable Ada code, and also an Event-B model. It is a model of the implementation, and contains flow control variables that model the flow of execution through the task body. The Ada code is produced from an intermediate model that is not visible to the user. The Common Language model (CLM), is generated from the Tasking Event-B by a translation tool. Ada (and other implementations) may be generated from the CLM. An overview of Tasking Event-B can be found here.

In the example so far, the Heating Controller has been refined to the point where we wish to add implementation constructs. The Event-B language is not expressive enough to fully describe the implementation. Tasking Event-B facilitates this final step to implementation, by extending Event-B with the necessary constructs. Event-B machines modelling tasks, shared objects and the environment are identified, and extended with the appropriate implementation details.

The example/tutorial projects are are available in the e-prints archive, or on SVN.

Heating_ControllerTutorial2_Completed An example project with an environment simulation. The environment variables are monitored and controlled using subroutine calls. The project contains a complete Tasking Development with generated Event-B and Ada code.
Heating_ControllerTutorial2_Partial1 A project with the final decomposition completed, ready to begin Tasking Event-B Development.
Heating_ControllerTutorial2_Partial2 A partially completed tasking specification for the continuation of the tutorial.
TheoriesForCG Contains the mathematical language translations; encoded as rules in a theory plug-in rule-base.

Using the Tasking Extension

The steps needed to generate code from an Event-B model, in this tutorial, are as follows,

Download and Copy the Theories

The translations of the Event-B mathematical language to the target language constructs are specified as rules in the theory plug-in. Two rule files are included for the example, and are available in the SVN. The files can be downloaded and copied into an Event-B project called MathExtensions. The theory must then be deployed. Right-Click on the theory file and select deploy to do this. The non-Event-B project, the original download may now be deleted.

Adding the Implementation Level Refinement

The final decomposition generates the machines that are required for code generation. However, it is not possible to edit the machines since they are machine generated, and therefore this is prohibited. In order to be able to modify the models we will refine the generated machines. This is where we begin with the Heating_ControllerTutorial2_Partial1 project. To refine the machines we can use the automatic refinement feature, but this presents us with two problems that are dealt with in the pre-processing step. It is also at this stage that any remaining non-deterministic constructs should be removed by replacing them with deterministic constructs.

TIP: Non-deterministic constructs cause strange characters to appear in the source code. If you see strange characters in the generated code, check for non-deterministic constructs in the implementation level machines.

Alter_Temperature_Sensor1 in Envir1Impl: action becomes ts1 := ts1 + 1
Alter_Temperature_Sensor2 in Envir1Impl: action becomes ts1 := ts1 + 1
Alter_Heater_Status in Envir1Impl: action becomes hss := FALSE
INITIALISATION in Heater_Monitor_TaskImpl: becomes shs := FALSE

We also need to add a typing flag to an invariant. We need to add it in only one place, and this is where an invariant is used type a variable, in the Heating Controller machine. The flag is used to guide the translator to the typing invariant. This is because there is more than one invariant involving that particular variable. They may also be added to guards where parameters are typed in guards, and the parameters are referred to in more than one guard.

  • Go to the Heater_Monitor_TaskImpl typing_shs invariant.
  • Add the typing flag, by right-clicking on the invariant and selecting typing from the menu.

Pre-processing

The pre-processing step should be a temporary, the solutions can be incorporated into the tool to automatically perform the changes that are required.

  • The Code Generator requires a flattened version of each machine; all of the Event-B elements should be available in the implementation level machine.
  • Composed machines are not currently able to be refined, so anything that requires synchronization of events requires some manual updates.
'Flattening' the Implementation Machines

The temporary solution for flattening:

  • Make events not extended.
  • Copy missing invariants.

I found the Event-B Machine Editor's synthesis view useful for this. Invariants can be copy-pasted into the implementation machine from the abstraction. (A dummy invariant can be added and selected for pasting)

Providing the correct Composed Machine

The composed machine problem is sub-divided into two sub-problems. Firstly composed machines cannot be refined, and secondly when a machine is further decomposed there is no link between the first composed machine and the newly generated composed machine. So one or both of these problems may occur, depending on the number of decompositions.

We must manually add the information to the composed machines to address these two problems.

The temporary solution for composed machines:

  • Modify the lowest level decomposed machine, HCtrl_M1_cmp, to include the implementation level machines (task names ending in *Impl). To do this,
  • open the composed machine editor. Open the INCLUDES edit feature.
  • Select the second drop-down box and find the *Impl version of each machine.
  • Save the composed machine.
  • Now add missing synchronizations to the composed machine. Add the Envir1Impl to the includes of HCtrl_M1_cmp.
  • Each composed event in the task, that synchronizes with the Environ machine, must have the remote event synchronization added manually. This can only be done by inspection of each composed event. We need to update Sense_Temperatures, Display_Current_Temperature, Actuate_OverHeat_Alram, Actuate_Heat_Source, Sense_Heater_Status, Actuate_NoHeat_Alarm, Sense_PressIncrease_Target_Temperature, Sense_PressDecrease_Target_Temperature, Display_Target_Temperature. One by one, expand the events in the composed events section of the composed machine editor; add a new event in the combines events section, select Envir1Impl and add the synchronizing event from the list-box to the right.

Adding Tasking Event-B

Each Machine should be completed as follows.

The Temp_Ctrl_TaskImpl Machine

Continuing with the tutorial project Heating_ControllerTutorial2_Partial2, we need to make changes to the following machines. During the tutorial we will cut and paste from Heating_ControllerTutorial2_Completed model when, specifying the task bodies, to save typing.

  • Add the Auto Task extension.
    • Right-Click on the Machine node in the Rose tree-editor,
    • and click on New Child Element/Auto Task Machine menu option.

Auto Tasks are tasks that will be declared and defined in the Main procedure of the implementation. The effect of this is that the Auto Tasks are created when the program first loads, and then activated (made ready to run) before the Main procedure body runs.

  • Edit the TaskBody.
    • Open the properties editor for the task body.
    • Copy and paste the task body from Heating_ControllerTutorial2_Completed/Temp_Ctrl_TaskImpl
    • Set the task type to Periodic,
    • Set a period of 250 milliseconds.
    • Click on the Set Task Body button.

The task body is parsed, and if successful will add the structure to the EMF tree. If parsing is not successful an error panel will display the source of the error.

We now look at the sensing event Sense_Temperatures event in Temp_Ctrl_TaskImpl. In order to assist with the translation we add the following annotation:

  • Add a Sensed Event Annotation.
    • Right-click on the Sense_Temperatures Event node.
    • Select New Child/Implementation from the menu.
    • Go to the Implementation properties view and set the Implementation Type property to Sensing.

We now look at the actuating event Display_Current_Temperatures event in Temp_Ctrl_TaskImpl. In order to assist with the translation we add the following annotation:

  • Add an Actuating Event Annotation.
    • Right-click on the Display_Current_Temperatures Event node.
    • Select New Child/Implementation from the menu.
    • Go to the Implementation properties view and set the Implementation Type property to Actuating.

The Shared Machine

The next step is to identify the Shared_ObjectImpl machine as a Shared Machine.

  • Right-click on the Shared_Object Machine node in the Rose tree-editor.
  • Select New Child/Shared Machine from the menu.

The Environ Machine

In the prepared machine we identify the Envir1Impl as an Environ Machine,

  • Add the Environ Machine extension.
    • Right-click on the Machine node in the Rose tree-editor.
    • Select the New Child Element/Auto Task Machine menu option.

In the implementation, Environ Tasks are declared and defined in the Main procedure . The Envir1Impl machine models a task that simulates the environment, and can be used to generate simulation code. For deployment in a non-simulated environment the environ machine's generated code can be ignored. To specify the Environment task's behaviour we add edit the task body.

  • Edit the TaskBody.
    • Open the properties editor for the task body.
    • Copy and paste the task body from Heating_ControllerTutorial2_Completed/Envir1Impl
    • Set the task type to Periodic,
    • Set a period of 100 milliseconds.
    • Click on the Set Task Body button.

When clicking on Set Task Body, the task body text is sent to the parser. If parsing is successful then a builder adds the structure to the EMF tree. If parsing fails then an error panel displays the source of the error.

The final step is to complete the Sense_Temperatures event. The event, being a kind of synchronization, synchronizes with the Sense_Temperatures event in the Temp_Ctrl_Task tasking machine. We annotate the model with sensing and actuating implementation types.

  • Add a Sensed Event Annotation.
    • Right-click on the Sense_Temperatures Event node.
    • Select New Child/Implementation from the menu.
    • Go to the Implementation properties view and set the Implementation Type property to Sensing.
  • Add an Actuating Event Annotation.
    • Right-click on the Display_Current_Temperatures Event node.
    • Select New Child/Implementation from the menu.
    • Go to the Implementation properties view and set the Implementation Type property to Actuating.

A Summary of Steps

For a Tasking Machine definition:

  1. Add the Tasking Machine type (Auto etc).
  2. Set the task type (Periodic etc.).
  3. Set the task priority.
  4. Specify the task body.
  5. For sensing/actuating events, add the Event Type.

For a Shared Machine definition:

  1. Add the SharedMachine Machine type.

For an Environ Machine definition:

  1. Make the type an Environ Machine type.
  2. Set the task type Periodic; a shorter period than the shortest task period is best for simulation.
  3. Set the task priority.
  4. Specify the task body, it will contain a simulation of changes in the environment.
  5. For each sensing/actuating event, add the Event Type.

Invoking the Translators

  • To generate Ada code,
    • Right-Click on the composed machine, or any tasking machine in the development, select Code Generation/Translate Event-B to Ada.
    • Open the generated code directory in the project to view the source files. A refresh will be necessary to make the code visible. The .gpr file has been provided for AdaCore GPS users.
  • To create the Event-B model of the implementation,
    • Right-Click on the composed machine, or any tasking machine in the development, select Code Generation/Translate Tasking Event-B to Event-B.
    • The Event-B model should be updated with the flow control variables. Users are not able to manually edit the generated elements. The additions can be removed using the menu option Code Generation/Remove Generated Event-B

Generated Code

Generated code should be visible in the code directory, in the Event-B project. You can see the directory in the resource view; or alternatively, click on the view menu in the Event-B perspective, select customize view, and uncheck the all file and folders filter.