How to Use the Smart Client Software Factory (SCSF) and the Composite Application Block (CAB) – the CSLA Project Tracker Reference Example

• Download Project Tracker - 550.32 KB
• Download SCSF Project Tracker - 1.7 MB

Introduction

The latest version of the Smart Client Software Factory (SCSF) has recently been released. In order to become familiar with the new version, I have taken the reference example of the CSLA framework and converted the Windows Forms solution to use the SCSF. But first some background.

The SCSF is a powerful framework which I have used successfully for some time – see SuperSec. The latest version of the framework contains some new features and I wanted to see how they worked. For all its power, the SCSF is not for the faint hearted. The learning curve is very steep, but once you are there, it is very easy to use and very effective.

The CSLA framework is a very handy way to build a client server application with mobile objects. A number of people have raised the issue of using the SCSF with CSLA in the CSLA forums, and the response has been that the two match well. But anyone wanting to work out how to use the CSLA with the SCSF was on his own.

So this paper attempts to show how the Project Tracker (PT) example can be converted to run using the SCSF.

Background

Now for the warnings! Rockford Lhotka who has developed the CSLA framework is an extremely bright and able developer. His PT example is a very nice example of the way to write a smart client application. I'm not sure that the SCSF adds a lot to the example. But of course, all we are attempting to do is show how to use the SCSF!

In addition, the SCSF brings with it a lot of overhead – a lot of overhead! The PT example looks particularly silly. A great deal of code to do not a lot! The recent debate on the use of CAB and SCSF has been very informative but in my opinion, the SCSF is a valuable tool, and I for one will stick with it until Acropolis is with us.

The rest of this paper describes the steps to convert the PT example to use the SCSF. If you haven't downloaded CSLA (and the ProjectTracker example), do so now. If you install the ProjectTracker example, then the database will be set up for you.

Using the Code

The source code is contained here.

The following is the way to duplicate it.

Step 1 – Create a SCSF Project

Clearly you need to have the May 2007 version of the SCSF installed.

Create a new SCSF application and call it SCSFProjectTracker. This creates a fully working smart client solution. Compile it and run it!

Step 2 – Add the Infrastructure.UI Module

The SCSF supplies most of what we need for the PT application. However the PT application makes use of modal forms. The SCSF reference implementation contains a useful module - Interface.UI – which provides the functionality we require. Simply copy this module and change the namespace.

Step 3 – Change the Layout Module to Match the PT MainForm

There is no Menu strip in the PT example – so delete it, and remove the reference to _mainMenuStrip.

Copy the ToolStrip from the PT MainForm to the ShellLayoutView, delete the existing ToolStrip, and rename the one you copied _mainToolStrip.

Delete all the ToolStripItems from the drop downs for Projects, Resources, Admin, and Documents. Register the Projects, Resources, Admin, and Documents drop downs and the Login label and button in the ShellLayoutViewPresenter OnSet method. Then add a command handler for the Login button.

Finally remove the LeftWorkspace from the SplitContainer, delete the SplitContainer, and dock the LeftWorkspace in the LayoutWorkspace. Rename it to _mainWorkspace.

In order for the application to compile, you will need to set the names in the UIExtensionNames, WorkSpaceNames, and CommandNames classes.

Add two Event Handlers for SetStatusBusy and CancelStatusBusy to the ShellApplicationLayoutPresenter.

Add two EventHandlers for DocumentActive and DocumentClosed so that when a Project or Resource is being edited, you can move easily between the views.

Add a reference to the Intrastructure.UI project, change WindowsWorkspace to WindowsWorkspaceExtended in the Module class, and register the modal workspace.

Finally create a service – ShellNotificationService – in the Infrastructure.Library module. This implements the IMessageBoxService and gives a unit testable way to provide message box functionality in your business modules. Register the service in the Infrastructure.Module.

Now all the UI elements you need are available to your SCSF business modules.

Compile and run the application.

Step 4 – Add the ProjectTracker.Library and CSLA references

To make the business objects available to the UI, copy ProjectTracker.Library.dll and Csla.dll to the Lib folder of the solution. Now when we require references to the business objects, we can get them from one place. The best way to get access to the ProjectTracker functions and to manage interaction with the database is to create a service.

Create a service ProjectTrackerService in the Infrastructure.Library project. This service implements IProjectTrackerService in the Infrastructure.Interface project so that it is available to all modules. Register the service in the Infrastructure.Module.

Step 5 – Add the LoginModule

The first business module you need is one to manage user login.

Add a new business module - LoginModule (without an Interface module).

The only view needed for this module is the LoginView. Add a LoginView using the SCSF Add View recipe. This is where the fun begins. The LoginView consists of three partial classes – LoginView.cs, LoginViewDesigner.cs, and LoginView.GeneratedCode.cs. We also now wish to separate out business logic from code which is strictly needed in the UI.

The login process is treated as a separate Workitem and managed by a LoginController. Again this is probably a bit of overkill but it provides an easy way to create a view and then dispose of all the resources which were used. Typically a User will log in once and this ensures that resources which are not used in the remainder of the session are not left hanging around.

Some points to note. When the user logs in or logs out, and event is fired to let other modules know that the logged in state has changed. The PT example uses a StatusBusy object to display a message in the status strip when database operations are taking place. This is replaced by firing an event when the database operation begins and when it ends.

The LoginView is displayed when the application starts (triggered in the AddViews method in the ModuleController), and when the User clicks the login button.

Step 6 – Add the ProjectModule

Add a business module using SCSF – the ProjectModule.

First add the ToolStripMenuItems to the Project ToolStripDropDown and register the elements and the commands in the ModuleController. To ensure that the ToolStripMenuItems are displayed correctly, add an ActionCatalogService and register a general action condition ProjectActionCondition. This ensures that the correct label is displayed and the menu items are enabled and disabled as appropriate. The ProjectActionCondition is triggered when the Login and Logout events are fired.

There are two views in this module – the ProjectSelectView and the ProjectEditView. In the same way as we did with the LoginView, create the two views using the SCSF recipes and transfer the code across from the PT sample.

The ability to select a project is needed in other modules. The best way to provide this capability is using a service ProjectSelectService. Create a service IProjectSelectService in Infrastructure.Interface and provide an implementation in Infrastructure.Library. Load the service in the ModuleController.

IProjectSelectService provides the methods to create a new project, edit an existing one or delete a project. This is the best way to make the ProjectSelect capability available to other modules.

Step 7 – Add the ResourceModule

Add a business module using the SCSF – the ResourceModule.

Creating the Resource functionality is similar to the process used in the ProjectModule.

Step 8 – Add the Assign Functionality

Now that both the ProjectSelectService and the ResourceSelectService have been created, the Assign Resource and AssignProject functionality can be added in ProjectEditViewPresenter and ResourceEditViewPresenter respectively.

Step 9 – Add the AdminModule

Next, add the AdminModule. This provides a single view – RolesEditView.

That's it. It's not difficult to do and it certainly shows the value of the SCSF and the CAB. I was able to test the modules independently, and if we wished to add more functionality, we can work on the appropriate Module on its own.

To run the example, use the user names and passwords – pm and pm, and admin and admin.

Points of Interest

The overhead associated with the CAB is really only obvious when the application loads. The original ProjectTracker application starts almost immediately while the SCSF version takes a few seconds. Thereafter like most smart client applications, the difference is not noticeable.

History

• 26 June 2007: Application published