LightSwitch Tip of the Day

Did you know that everything you design in a LightSwitch application (tables, screens, queries etc) is stored in a file called ApplicationDefinition.lsml?
LSML extension stands for the title of the post…no, I’m kidding of course. It stands for LightSwitch Markup Language. This file can be found in the folder <Project Path>\<Project Name>\Data.
Working in Logical View this is file is not visible (no files are visible in this view either way). Turning to File View you can see links to this file in all three projects Client, Common and Server. Notice they are links. The original file is not included directly in any project.
The reason there is only one file and all projects have link to it, is that it’s common to all of them and any change made to it should be available simultaneously to all projects.
The reason it’s not included to any project, in my humble opinion, is mainly because it’s not meant to be edited in any way. It could be included in the Common project for example as it IS common.This file is the product of all designer work done in LightSwitch. Even when you change the Theme, or Access Type properties of the application from the Properties of the project this change is stored in this file.
This is the reason also, that only ONE (or none) “<Project Name> Designer” window is available at any given time in your workspace. Because there IS only one such window displaying a different part of the ApplicationDefinition.lsml file every time you double-click a table or a form or whatever opens a designer window.
One tip for the end. When you plan a major change in your model (data design), especially if you are NOT using a native datasource, keep a backup of ApplicationDefinition.lsml. If you are using version control, check a version in, even temporarily. If not, keep a backup copy of the file. One day you might thank me for this advice…

Did you know that, when you create a native datasource in LightSwitch managing tables (entities) from the LightSwitch designer, the corresponding schema along with the data manipulated while debugging are stored in a SQL server database file set found in <ProjectName>\Bin\Data?
These database files are attached to the local instance of SQL 2008 Express. Visual Studio LightSwitch will install one if not found. The SQL server instance must be configured to allow user instances, as by default LightSwitch will attach the aforementioned files as a user instance. Along with your schema, default ASP.NET security schema is also found there.
The connection string compacting all the above can be found in the web.config file of the ServerGenerated project. If you don’t know what or where is this don’t worry we will talk about it in a next post. Just go ctrl+shift+F enter _IntrinsicData as the string to find and search in the entire solution. Please don’t touch. Generated, you know…

Did you know you can find LightSwitch self-training resources in places like:
LightSwitch Team Blog
LightSwitch Developer Center
LightSwitch Help Website
Open Light Group
And here you can find a list of many, many more LightSwitch related links.
One thing is for sure, LightSwitch is worth learning