In 2010, Microsoft announced LightSwitch, a product aimed at developing Line-of-Business applications with ease. In July 2011, the beta tag was finally removed from the product as Microsoft officially introduced Visual Studio LightSwitch 2011 as a new member of the Visual Studio family. Many however are still unsure about the product. Questions crossing a lot of minds include “Is it something for me?”, “What can I do with it?”, “Where should I use it?”, “Is it more than Microsoft Access?”, “Am I limited to what’s in the box?” and quite a few more.
For this reason, I have decided that a few articles are in place to give you a clear understanding of LightSwitch. I won’t be saying that you should LightSwitch for this or that. Using a sample application we will build throughout the series, I will try giving you an overview of how we can use it to build a real-world application. By reading these articles, I hope you’ll be able to make up your mind whether or not LightSwitch is something for you.
More specifically, I plan the following topics to be tackled along the way:
- What is LightSwitch and where I see it being useful
- The concepts of a LightSwitch application
- Data in more detail
- Screens in more detail
- Queries in more detail
- Writing business logic and validation
- Managing security in a LightSwitch application
- Deploying a LightSwitch application
- Extensions - what and how
- Using custom Silverlight controls in LightSwitch
- Adapting the LightSwitch UI to your needs
- Using RIA Services
In this first article, we’ll start by looking at what LightSwitch is and we’ll look at the concepts as well. First, let’s introduce the scenario we’ll use for this series.
The scenario
Imagine you are asked to build a new system for a movie theatre named MoviePolis. Today, they are using an old application which was written in COBOL and it consists out of several old-school screens, with absolutely no user experience at all. A typical interface of such an application is shown below.
As can be seen, this is not how we do things nowadays. That’s why MoviePolis wants a new system.
Their old system manages the following data:
- Movies
- Distributors
- Show times
- Tickets
Movies can be managed, they are owned by a movie distributor. For showing movies, show times are created. For show times, tickets can be purchased. This system already contains several interfaces, which are to be used by different people in the system: a manager will buy movies or add new distributors. An employee can manage show times. Ticket staff can view the interface to sell tickets for a show time.
Let’s now look at where LightSwitch in general can be used and what it really is.
Where is LightSwitch a good fit?
As a consultant, I’ve seen several times that non-technical people (sometimes with some technical background) have created applications, mostly in Excel or Access. There’s nothing wrong with that, absolutely not. Sometimes, even an entire organization runs on such an application. Things however may get difficult if that person decides to leave the company. In some cases, a consultant is hired to figure out how things work. Sadly, that’s costly and often very difficult to find out what is in the “application” and how it works (things like business rules, valid data etc). One of, if not the biggest problems here is that everyone creates such applications in their own way: there’s no consistency whatsoever. These people default to Access or Excel because it doesn’t require them to learn developing applications with a framework such as .NET. They get up-to-speed fast. Here, LightSwitch would be a good alternative. As we’ll see later on, there’s no development knowledge required to build a working application with LightSwitch. Not everything however can be done without writing code, so a good approach here might be that the non-technical/business person creates the rough outline of the application and a developer can then add finishing touches (that is, adding code to validate etc).
Reading this may get you thinking that I see LightSwitch as a tool only for those people. Well, I certainly don’t. In systems that I’ve build, very often typical administration screens need to be built. Things like managing countries, currencies, languages… Screens may have to be built for that type of data while there’s little business value here. Building those screens manually costs time (and therefore money). If we have these generated by LightSwitch, we’ll definitely make some profit.
Also, I see LightSwitch as a valid alternative for small applications. Very often, we as developers spend a lot of time thinking how we are going to build the application. Lot of time goes wasted in thinking about an architecture, a data access layer… even for small applications. LightSwitch can be a valid development platform here as well, since it has everything on board to get started, based on a solid foundation using Silverlight, RIA Services, MVVM etc.
Finally, using the extensibility features (which we’ll be looking at further down the road), a team of developers can build a number of extensions, typical for the business. Business persons can then use these extensions to create applications that are already tailored to the need of the business, without having to write logic.
Hello LightSwitch
Now that we have a bit of a clearer view on who could use LightSwitch and where it can be used, we can conclude that LightSwitch is a platform, part of the Visual Studio family, that allows building LOB applications in a rapid way. It allows people to build applications without writing code but it doesn’t block you from writing code. As developers, the tool can be used to build real applications, including validations etc. It has a rich extensibility framework that enables to build extensions to further customize the tool and the application that we are developing.
The applications we build are in fact Silverlight application. Because of this, LightSwitch applications can be deployed on the desktop (Silverlight out-of-browser application) and in-browser (Silverlight in-browser application). LightSwitch applications can be deployed to Windows Azure as well.
LightSwitch can be downloaded from http://www.microsoft.com/visualstudio/en-us/lightswitch. It can be installed in two ways. If you have Visual Studio 2010 already installed, it will integrate and become a new type of template that you can select. If not, it will install the Visual Studio Shell and it can run stand-alone.
Let’s now take a look at the foundations of a LightSwitch application.
Foundations of LightSwitch development
Any LightSwitch application evolves around 3 important foundations: data, screens and queries.
Data is where it all starts. Since LightSwitch is aimed at building LOB applications, it’s no wonder that we should start with the data aspect. LightSwitch has several options of working with data. It can work with a SQL Express database that it manages itself, it can connect to an existing SQL Server database or it can get data from a SharePoint list. On top of that, LightSwitch can consume WCF RIA Services, therefore. Because of this, we can virtually connect to any type of data source where RIA Services serves as some kind of middle tier to get and store data. We’ll look at this further in this series.
The default option is creating the application using an internal SQL Server Express database. In this case, we define the data from within the LightSwitch environment. Based on this data, LightSwitch can then be used to generate screens. Note that in one application, we can connect to an internal LightSwitch database and several external data sources. This way, it’s even possible to create relations between the several data sources: LightSwitch allows creating relations between entities inside the internal database and between the internal and any external database. It cannot change external databases though.
Once the data is defined, we can start generating screens on top of this data. (Note that LightSwitch supports an iterative way of working, so we can easily make changes to the data and alter the screens later on.) A screen can be created based on a template. Out-of-the-box, LightSwitch has some templates already; we as developers can create new templates as well. A screen template is as the word says nothing more than a template. We can change the screen once it’s generated to better fit our application needs.
The third and final foundation is queries. A query is the link between the data and the screen. A screen is always generated based on a query that runs on the data. Even if we don’t specify a query, a default query (Select * from …) is generated. We can change queries and we can create queries as well. We’ll be looking at how to do so later on.
Creating the MoviePolis application
Of course we can’t finish of the first part of this series without showing LightSwitch. Therefore, we’ll start with building the foundations of the application. In the next parts, we’ll be extending on this application a lot further.
So open Visual Studio LightSwitch and follow along to build the application. For the purpose of this demo, we create a LightSwitch C# application and name it MoviePolis.
When Visual Studio is ready creating the application from the template, we get the following screen. Note that LightSwitch suggest we connect to data first. For our demo, we are going to use the first option: we’ll create the data from scratch
Data of MoviePolis
As said, we should start with the data. In the solution explorer, we have 2 options: Data Sources and Screens. Right-click on Data Source and select Add Table. In the table/entity designer that appears, we can create our entity. Create the Movie entity as shown below.
Next, we’ll create the Distributor entity as shown below.
A Movie is distributed by a Distributor. We should therefore embed this information in a relation. In the designer with the Movie entity open, click on the Add relationship button. A dialog appears as shown below. Create the relationship so that one Distributor can have many Movie entities but each Movie can only have one Distributor.
The result is that this relation is shown in the designer.
For now, that’s enough data; we’ll model the other entities in the following articles.
Give me some screen
Now that we have our data model created in LightSwitch, we can move to creating some screens. In the solution explorer, right-click on the Screens folder and select Add Screen. In the dialog that appears, we see a list of screen templates that come with LightSwitch. Developers can create new ones, but for now, we’ll use one of the standard ones. Create a new List and Details screen and select that you want to use the Distributor entity. Mark that we also want to be able to edit the Movie data. The screenshot below shows these options.
LightSwitch will now reflect on the entity and generate a screen, based on this template. The screen designer shows a hierarchical view of the generated screen. Note that behind the scenes, code was generated. When we start editing this screen, this code will be changed.
Without any further ado, let’s run the application (remember to have your SQL Express instance running!). You’ll get a screen as shown below. We can edit the Distributor as well as add Movie instances.
At this point, we have a working application that handles things like adding, updating and deleting data.
Of course, we’ve only scratched the surface. In the following article, we’ll do a deep dive in all the options we have to work with data and screens and I’ll be telling you more on what happens behind the scenes. Stay tuned!
About Gill Cleeren
Gill Cleeren is Microsoft Regional Director (www.theregion.com), Silverlight MVP (former ASP.NET MVP), INETA speaker bureau member and Silverlight Insider. He lives in Belgium where he works as .NET architect at Ordina. Passionate about .NET, he’s always playing with the newest bits. In his role as Regional Director, Gill has given many sessions, webcasts and trainings on new as well as existing technologies, such as Silverlight, ASP.NET and WPF at conferences including TechEd Berlin 2010, TechDays Belgium, DevDays NL, NDC Oslo Norway, SQL Server Saturday Switzerland, Spring Conference UK, Silverlight Roadshow in Sweden… He’s also the author of many articles in various developer magazines and for SilverlightShow.net. He is also SilverlightShow.net most appreciated webinar presenter, with 7 webinars delivered so far. Gill organizes the yearly Community Day event in Belgium.
He also leads Visug (www.visug.be), the largest .NET user group in Belgium. Gill recently published his first book: “Silverlight 4 Data and Services Cookbook” (Packt Publishing). You can find his blog at www.snowball.be.
Twitter: @gillcleeren