BUILDING A COM/ATL C# CLIENT

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1 BUILDING A COM/ATL C# CLIENT Bob Coker rcoker06@gmail.com May 27, 2015 OVERVIEW 1. Project Background and Description Before building the COM/ATL client, build the COM/ATL server. The article for this is at: The is the second of a multi-part article on how to do the following: Build a C++ ATL local server. This server will use user defined types and SAFEARRAYs to pass data. Build a C# client that communicates to an ATL local server. Pass user defined types to an ATL local server from a C# client. Modify the ATL server to communicate with VBA scripts using the APC library. 2. Building the COM/ATL Client 1. Fire up Visual Studio. 2. Create a new blank solution. Call the solution MuscleCarClient: 3. Now add a new project. Select Visual C# and WPF Application Project. Name the project MuscleCarClient: 1

2 4. Go to MainWindow.xaml in the designer and add a button with text: Get Specifications. Name the button, BtnGetSpecifications: 5. Double click on the button in the designer to add a click handler to the code behind: 2

3 6. Add a reference to the MuscleCarServerLib. This should be available in the Type libraries list if you have compiled the ATL/COM server: 7. Add a variable for the MuscleCarApp and create an instance of the object in the MainWindow constructor: private MuscleCarApp _musclecarapp; public MainWindow() InitializeComponent(); _musclecarapp = new MuscleCarApp(); 8. Now create the CarInfo array inside the button click handler: var carinfo = new CarInfo(); var make = new string[] "Chevrolet", "Dodge", "Ford" ; var model = new string[] "Camaro", "Challenger", "Mustang" ; var trim = new string[] "SS", "R/T", "Shelby GT350" ; var engine = new string[3]; var engineliters = new double[3]; var horsepower = new double[3]; carinfo.make = make; carinfo.model = model; carinfo.trim = trim; carinfo.engine = engine; carinfo.engineliters = engineliters; carinfo.horsepower = horsepower; 9. Now add code to call the COM/ATL server to get the specifications: 3

4 _musclecarapp.getspecifications(ref carinfo); 10. We need at this point to assign the return values to arrays. The CarInfo structure is made up of arrays that are passed as objects. So these need to be cast to Array types: var amake = (Array)carInfo.Make; var amodel = (Array)carInfo.Model; var atrim = (Array)carInfo.Trim; var aengine = (Array)carInfo.Engine; var aengineliters = (Array)carInfo.EngineLiters; var ahorsepower = (Array)carInfo.Horsepower; 11. Now we will iterate through the arrays (they are all the same size, remember?) and will display a message box for each item: var carinfo = new CarInfo(); var make = new string[] "Chevrolet", "Dodge", "Ford" ; var model = new string[] "Camaro", "Challenger", "Mustang" ; var trim = new string[] "SS", "R/T", "Shelby GT350" ; var engine = new string[3]; var engineliters = new double[3]; var horsepower = new double[3]; carinfo.make = make; carinfo.model = model; carinfo.trim = trim; carinfo.engine = engine; carinfo.engineliters = engineliters; carinfo.horsepower = horsepower; _musclecarapp.getspecifications(ref carinfo); var amake = (Array)carInfo.Make; var amodel = (Array)carInfo.Model; var atrim = (Array)carInfo.Trim; var aengine = (Array)carInfo.Engine; var aengineliters = (Array)carInfo.EngineLiters; var ahorsepower = (Array)carInfo.Horsepower; for( var i = 0; i < 3; i++ ) var msg = string.format("make: 0\nModel: 1\nTrim: 2\nEngine: 3\nLiters: 4\nHorsePower: 5", amake.getvalue(i), amodel.getvalue(i), atrim.getvalue(i), aengine.getvalue(i), aengineliters.getvalue(i), ahorsepower.getvalue(i)); MessageBox.Show(msg); 12. When you run the application, you should see a message for each make: 4

5 5 13. That is all for the COM/ATL client. We will come back to this application in part 3 of this series, when we add support for VBA scripting. Other articles in this series can be found at: