Presentation of the problem:
Deleting behaviour with compartments representing embeddings
Most of the time, in the DSL Tools, you map compartments in compartment shapes to embedding relationships.
And then, deleting a compartment item in the compartment shape indeed removes the model element which was displayed as this compartment item, which makes sense.
Deleting behaviour with compartments representing reference relationships
Now let's suppose you have are mapping a compartment not to an embedding, but to a reference relationship. You might think that deleting a compartment item will only delete the link between the instance represented by the compartment shape and the instance represented by the compartment item. But it turns out that it also deletes the instance represented by the compartment item.
There are scenarios, where you would like first behaviour. This posts explains why it is so, and how to proceed to have only the link deleted, not the target model element.
A case study: what it does, and what we would want
The domain model
- we have 2 domain classes ClassA and ClassB, linked thru a Reference relationship (many-many) named ClassAReferencesClassB
- ClassB is represented as a geometric shape ClassBShape
- ClassB is represented by a compartment shape ClassAShape, which displays the ClassBs referenced by the instance of ClassA through ClassAReferencesClassB
- the same ClassAReferencesClassB is also represented by a connector, so that we really see what is happening there.
Figure 1: the domain model (please, click the image to enlarge)
Opening the DSL Details tool window, and clicking on the mapping line between ClassA and ClassAShape, in the Compartment Maps tab, we use the path editor as we usually do and end-up with the following, which really means that in the Bs compartment, we are:
- requesting to represent ClassB instances, which we get though the ClassAReferencesClassB relationship navigating though the ClassB role (Displayed elements collection path)
- Then we want to display the Name of each ClassB (Display property).
Figure 2: The mapping between ClassA and the compartment shape representing it.
Running our designer - what it does
After transforming all templates, and running the editor, you create a ClassA , a ClassB , and connect them through the connector, in order to get this (the ClassB1 instance also appears in the compartment, since the relationship is mapped both to the compartment and the connector)
Figure 3: Running our designer - starting point
Now, let's try to delete ClassB1 from the compartment (Using the Del key or the contextual Delete command). You end-up with this:
- the ClassB1 represented instance was deleted (after all the Delete command was targeting it), removing the link, of course
- consequently the ClassB1 shape was deleted
Figure 3: Running our designer - what Delete does on the compartment item
Running our designer - What we would like
That said. You were maybe expecting that, considering you were using a Reference relationship and not an embedding, you would end-up with only deleting the link between ClassA1 and ClassB1 and not the ClassB1 instance. It turns out that this scenario is of interest, but this is not what you requested. You really sent the Delete command to the ClassB1 instance, hence the result.
How to get what we want
In fact, to tell you the truth, I thought myself this behaviour was a bug :-), until Stuart explained me about the command being directed to the ClassBs instances and not to the link. Then, you can very easily achieve our desired behaviour specifying the right things in the DSL Details window on the shape map (and not writing any custom code)
Here is how we should proceed.
- Still in the Compartment Maps tab of our mapping between ClassA and ClassAShape, we need to express that we want to deal not with ClassB instances but with a collection of ClassAReferencesClassBlinks form the instance of ClassA represented by the compartment shape to the related ClassB instances.
The Displayed elements collection path should, therefore be ClassAReferencesClassB.ClassB
This can be understood as the same code construct as ClassAReferencesClassB.GetLinksToClassB(ClassA1) which returns collection of ClassAReferencesClassB. This is really an instance of the link that will be presented as a compartment item, and thus, deleting it will delete the link, not the targeted ClassB.
- Now, we need to specify what to display (namely the Name property of the ClassB instance accessed through the link). For that, given an instance of ClassAReferencesClassB, we need to get an instance of ClassB (just in order to access its property). We express this in the Path to display property field as ClassAReferencesClassB!ClassB which means getting the ClassB property of the ClassAReferencesClassB instance, that is getting a ClassB instance.
- The last step is to provide the Display property, here Name
Figure 4: how to express we want to deal with links
Running our designer - We get what we want
After transforming all templates, and running the designer the first thing is you get exactly the same appearance as before (even if now the compartment items represent links and not model element instances). This is no surprise because we did all we could for that, but it's work noting it
Figure 5: Running our new designer - apparently this is like before
But this, time, deleting the ClassB1 compartment item, we end up with the following expected result:
Figure 6: Running our new designer - the delete command now delete the link, not the targeted shape
Conclusion
In this post, we learnt why, when mapping a compartment to a reference relationship, deleting compartment items deletes the targeted model element with the usual mapping, and how to change the mapping so that it only deletes the link.
To get more information about the path syntax, you can review Overview of Domain Path Syntax . When I started with the DSL tools, I also found this post by Alan very useful.
As you might know, James and I are currently doing a VSX Tour in Europe. James already provided information in his blog about the different steps, in Brussels, Amsterdam, and Munich.
For the ones who would be interested in the event in Belgium:
- Katrien, who welcomed us and took care of us in Brussels, provides the links on the WebCasts recorded during the user group in Belgium.
- There is also a nice feedback on our session in David Sleeckx's blog. Thanks, David !
I'm currently visiting the VSX team in Redmond, introducing myself and meeting everybody. I'll be there for two weeks.
I arrived yesterday afternoon after a 23 hours trip from France, and Ken Levy invited me to a party at Ted Neward's house, along with Pablo Galiano It was a great occasion to speak with MVPs and VSX developers, even if I was very tired.
Today I began my first meetings with the members of the team. In the next couple of days, I'll have meetings with various team members, and will participate to the MVP Summit - Communities Side Session on Thursday.
It's really great to meet everybody, and to get more understanding of the VS SDK's overall development life cycle, as well as meeting the VSX community members. All this will enable me to participate in helping add new features to DSL tools and to enhance the VS SDK, working to enhance VSX development. :-)
As I told you in my previous post, the DslFactory community created a lot of content about DslTools and more generally Visual Studio Extensibility. This content is freely available, although written in French. Most of it is very interesting: For instance, DslFactory organized, on October 16th 2007, in Paris, along with Microsoft France, a complete day about Visual Studio customizations and extensibility named 9french) VSX Day 07.
The VSX Day 07 explained
The VSX Day, that is not less than 19 sessions whose content was filmed and is available as WebCasts (in French, of course) on Microsoft France Vision site.
These sessions are organized as a pathways, illustrated as a metro map, enabling us to discover the visual studio extensibility in a kind of progressive way. Starting from the Visual Studio customizations we ended the day by the the VS 2008 Shell, going through VSI, Snippets, VS Templates, GAX, Automation by macros and DTE, Add-ins, a VS SDK's Tour, Packages, DSLs, advanced DSLs such as bidirectional ones, with many demos, including Alain Metge brilliant Candle, and the WCF Designer. During the full day we also incrementally demoed a sample which was the pretext to navigate through these technologies : The creation of clickable images from class diagrams, and other DSL diagrams, and their inclusion in a Reference documentation thru add-in to SandCastle, and SandCastleHelpFileBuilder. Quite a lot of information for the attendees (the legend tells they would have been 200 :-) )
The VSX Day web casts
The Webcasts sessions of the day VSX Day can be found at the "Vision" Microsoft France:
Note that these links will take you to lists of more detailed WebCasts (it takes a little digging to find some WebCasts for the moment)
The VSX Slides
After a short introduction, DslFactory presented the issue of industrializing reference materials - which we serve as a leitmotif of this day - and the extension of Visual Studio responding.
The different extensibility scalability were then presented, from the most accessible to most powerful:
- The simple Visual Studio customization templates, wizards, and the use of GAX Guidances we already provide significant opportunities
- Then came the time to start coding with automation by Macros and Add-In
- Then, the Tour of the "Visual Studio SDK" allowed us to quickly learn about all these technologies most of which are ignored, and what they can do for us.
- A special focus was then carried out on some of these technologies:
- The afternoon was entirely devoted to the Domain Specific Languages (DSL) and their implementation in Visual Studio Opens via DSL Tools. Beginners, as confirmed users have, hopefully, been able to find answers to their questions
- We ended the day by lifting the veil on scalability VS 2008, and providing useful links
If you are interested in a particular subject, you can download a summary as a . pps file, and click subway stations. You will be taken directly to the corresponding powerpoint presentations.
The code samples
Associated with each session, DslFactory also provides the code of the demoed samples:
- 1. 1. Leitmotif: Demoed by Sebastian, with 3 examples. Chm before and after using SandCastle Add-ins and SandCastleHelpFileBuilder 1-FilRouge.zip (998 kb)
- 2. 2. Customizing VS:
- The demonstration by Alain on Visual Studio Policy: 2-VSPolicy.zip (2.14 MB).
- Moreover, the DSL "DSL4VSI" that Alain created to generate Visual Studio Installer (VSI) capable of installing 'Code Snippet', 'VSTemplate', 'Macro Project', 'Addin', 'Control Toolbox' is available on CodePlex in http://www.codeplex.com/dsl4vsi
- 3. 3. Automation API and Add-ins.
- The Visual Studio solution that I used inmy demos on the implementation of ProjectModel (list of projects and files), CoreModel (enumeration of windows) CodeModel (dynamic creation of a solution containing a draft containing serializable class): 3.1-AutomationAPI.zip (559 kb)
- The source code and binaries for the Add-in for Sebastien to generate clickable iamges from ClassDiagrams: 3.2-Add-ins.zip (25.3 kb)
- 4. VS SDK Tour has been a Live demo, which you can find in the WebCast.
For next demos, except the 6.1, you must install the VS SDK 4.0 for Visual Studio 2005
- 4.5. Regarding the demonstration associated with the presentation of the discovery of the packages, the 4.5-Packages.zip archive (7.81 MB) includes the 8 step of building the ReferenceDocumentationGenerator package to export clickable images
corresponding to ClassDiagram and DSL, and choose Export options, as well as to export diagrams.
- 5.2. Sebastien's Demo on creating a DSL for geometric shapes includes 7 steps, the establishment of the Domain Model with the DSL Tools for deployment. These steps have been grouped in 5.2-VSX-Day-solutions . zip (8 MB)
- 6.1. 6.1. Session advanced customization aspects of the properties window with the concepts of the System.ComponentModel namespace by Alain are available in 6.1-ComponentModel.zip ( 53 KO)
- 6.2. The demonstration of the session Using the Domain Model is in this archive: 6.2-UtilisationModele-ReferenceDocumentationGenerator.zip (755 KB). It is also part of the archive of the sesssion 4.5 Packages on which it is the 8th step.
- 6.3. The amendment to DSL Sebastian him for advanced functions such as the Model <-> Code bidirectionality is, also in 6.3-Bidirectionnalite.zip (2.90 MB)
That's it for an overview of the VSX Day
In my next post, I'll talk a little more about some Labs and Workshop that DslFactory produced to learn DSL Tools.
I started a few days ago in the Visual Studio Ecosystem team.
During my last 19 years I worked in the French Ministry of Defence building operational analysis software, and simulation applications to make decisions. A few years ago, I started creating a simulation development environment. This is were I got the passion for modelling, and discovered the DSL Tools. This lead me to get more interested in Visual Studio Extensibility, and, with a few friends, we created a French community about VSX and DSL Tools, which you'll find at http://www.dslfactory.org.
This is actually a great community, but there is one inconvenient for most people in the world : this is all written in French!
I hope to use this blog to share with you it's content, and also my discoveries on the long running path of understanding the Visual Studio SDK.
