ASP.NET Web PDF Document Viewer/Editor Control Library

For Visual Studio to be able to connect to our console-hosted service we need the service to be up and running before the Add Service Reference dialog is open. The easiest way to do this is to run the project, without debugging it. Instead of pressing F5, we choose Debug Start Without Debugging, or we press Ctrl-F5. This runs the ChatHost program without debugging, leaving Visual Studio free for other tasks, such as adding a service reference. We ll need the address of the service handy, and since it s quite long, it s easiest to open our host s App.config and copy the service address to the clipboard. (It s the baseAddress attribute in the <host> section.) Then we can go to the ChatClient project and add a Service Reference. If we paste the address of the service into the Address box and then click the Go button, after a few seconds we ll see the Services panel on the left display a ChatService entry. Expanding this shows an IChatService item representing the contract, and selecting this shows the one operation available in our contract, PostNote, as Figure 13-6 shows. While the list of services, contracts, and operations in the Add Service Reference dialog is useful for verifying that we have the service we wanted, the significance of the information here goes a little deeper it s part of an important feature of how systems communicate in WCF. Remember that we defined a contract earlier, to describe the operations our service provides to its clients. For the client to communicate successfully with the server, it also needs a copy of that contract. So the best way to think of the Add Service Reference dialog is that it s a tool for getting hold of the contract from a service.

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This is the purpose of the metadata exchange entry we saw earlier when we looked at the configuration Visual Studio generated for our WCF service. Metadata exchange is just a fancy way of saying that a service provides a way for a client to discover the contract and related information about the service. The Add Service Reference dialog uses this information to configure a client application to communicate with the service, and to provide it with a copy of the contract. To see the results of this, we ll finish with this dialog. In the Namespace text box near the bottom, we ll type ChatService Visual Studio will put the contract and any other types relating to this service into this namespace. When we click OK a Service References item appears in the project in the Solution Explorer, and it will contain an entry called ChatService. (Now that we ve done this, we can stop the service host console window we ran earlier.) Visual Studio generates some code when adding a service reference. By default, it hides this, but we can take a look at it. At the top of the Solution Explorer, there s a toolbar, and if you hover your mouse pointer over the buttons you ll find that one has a tool tip of Show All Files. This button toggles each time you click it. When it s pressed in, the ChatService service reference can be expanded, as Figure 13-7 shows.

The most interesting file in here is Reference.cs, inside the Reference.svcmap item. Inside this file, near the top, there s a copy of IChatService the contract we wrote earlier:

If the contents of a dialog are not stretched when the dialog is resized, the problem is most likely that Tip you have forgotten to add a top-level layout. Select the dialog form itself and apply a layout that should solve the problem.

[System.CodeDom.Compiler.GeneratedCodeAttribute("System.ServiceModel", "4.0.0.0")] [System.ServiceModel.ServiceContractAttribute( ConfigurationName="ChatService.IChatService"] public interface IChatService { [System.ServiceModel.OperationContractAttribute( Action="http://tempuri.org/IChatService/PostNote", ReplyAction="http://tempuri.org/IChatService/PostNoteResponse")] void PostNote(string from, string note);

}

It looks a little more complex than the original, because Visual Studio has annotated it with various attributes, but it s simply being explicit about the values that WCF fills in by default. Aside from these extra details, you can see that it is essentially a copy of the original contract.

paneXAxisType = AxisTypeDate; paneXAxisGridDashOff = 0; LineItem priceCurve = paneAddCurve( "Closing Price", pt, ColorSlateBlue, SymbolTypeNone); priceCurveLineWidth = 20F; paneAxisFill = new Fill(ColorWhite, ColorAntiqueWhite); paneXAxisMinGrace = 0; paneXAxisMaxGrace = 0; paneYAxisMinGrace = 0; paneYAxisMaxGrace = 0; paneAxisChange(g); } } This event handler takes two parameters The first is the base SystemDrawingGraphics object To render the graph, right at the bottom of the event handler, the SystemDrawing Graphics object is passed to the AxisChange method of a ZedGraph pane to refresh and redraw the graph The second parameter is a reference to the ZedGraph master pane, which is the collection of drawing surfaces that the ZedGraph exposes Check out the ZedGraph documentation for information about how to use the panes to create different drawing surfaces.

You might wonder why we jumped through all these hoops rather than just copying IChatService from the service project to the client. In fact, that would have worked, and we could even have written a separate DLL project to define the contract interface and shared that DLL across the two projects. As you ll see shortly, Visual Studio generated a few other useful things for us as part of this Add Service Reference process, but as it happens, sharing the contract definition directly is sometimes a perfectly reasonable thing to do you re not obliged to use metadata exchange. Of course, you won t always own the code at both ends. If you need to connect to a service on the Internet provided by someone else, metadata exchange becomes more important it provides a way to get hold of a contract you didn t write. And since the metadata exchange mechanisms are standards-based, this can work even when the service is not written in .NET.

Figure 2-17. A grid layout has been applied to the form itself and all its contents Now you have placed a number of widgets in layouts forming a dialog. You can try out the dialog in different styles using the preview function available from the Form menu. Try