This page shows how to create an Ice application with C#.
On this page:
Create Projects for your Client and Server Applications
We create two projects, one for the Server application and one for the Client application. These are regular Console projects with very little Ice-specific additions.
Open Visual Studio and create a new Console Application
Create the client project using "File > Add > New Project..."
zeroc.ice.net NuGet package to the projects with the NuGet Package Manager, found in "Tools > NuGet Package Manager > Manage NuGet Packages for Solution...".
Open a new Command Prompt a run the following command to create the server and client projects:
This generates a new .NET Core console application project in the
Then add references to the
zeroc.ice.net NuGet packages to this project:
Finally, repeat these steps for the client project:
Compile your Slice File
The next step is to add the Slice file (
Printer.ice) created earlier to each project, and then compile this Slice file.
Open the "Project > Add Existing Item" dialog and add
Printer.ice to your Project:
If you have automatic building disabled, select
Build to build your project. The build generates
Printer.ice (using Ice Builder) and then compiles both
generated\Printer.cs and the default no-op
Ice Builder invokes the Slice to C# compiler (
slice2cs) to compile Slice files into C# files.
Add a Slice item that includes
Printer.ice to your two projects. The code below shows the client project:
When building the project, the
SliceCompile task (imported automatically from the
zeroc.icebuilder.msbuild NuGet package) compiles
generated/Printer.cs using the Slice to C# compiler, slice2cs.
Use the following command to build the projects:
Write and Compile your Server
To implement our
Printer interface, we must create a servant class. By convention, a servant class uses the name of its interface with an
I-suffix, so our servant class is called
PrinterI and we will place it into the default C# source file Program.cs:
PrinterI class inherits from a base class called
PrinterDisp_, which is generated by the
slice2cs compiler. The base class is abstract and contains a
printString method that accepts a string for the printer to print and a parameter of type
Ice.Current. (For now we will ignore the
Ice.Current parameter.) Our implementation of the
printString method simply writes its argument to the terminal.
The remainder of the server code follows in
Program.cs and is shown in full here:
The body of
Main contains a
try block in which we place all the server code, followed by a
catch block. The catch block catches all exceptions that may be thrown by the code; the intent is that, if the code encounters an unexpected run-time exception anywhere, the stack is unwound all the way back to
Main, which prints the exception and then returns failure to the operating system.
Ice.Communicator object implements
IDisposable, which allows us to use the
using statement for the initialization of the
Ice.Communicator object. This ensures the communicator
destroy method is called when the
using block goes out of scope. Doing this is essential in order to correctly finalize the Ice run time.
The body of our
try block contains the actual server code.
The code goes through the following steps:
- We initialize the Ice run time by calling
Ice.Util.initialize. (We pass
argsto this call because the server may have command-line arguments that are of interest to the run time; for this example, the server does not require any command-line arguments.) The call to
Ice.Communicatorreference, which is the main object in the Ice run time.
- We create an object adapter by calling
Communicatorinstance. The arguments we pass are
"SimplePrinterAdapter"(which is the name of the adapter) and
"default -p 10000", which instructs the adapter to listen for incoming requests using the default protocol (TCP/IP) at port number 10000.
- At this point, the server-side run time is initialized and we create a servant for our
Printerinterface by instantiating a
- We inform the object adapter of the presence of a new servant by calling
addon the adapter; the arguments to
addare the servant we have just instantiated, plus an identifier. In this case, the string
"SimplePrinter"is the name of the Ice object. (If we had multiple printers, each would have a different name or, more correctly, a different object identity.)
- Next, we activate the adapter by calling its
activatemethod. (The adapter is initially created in a holding state; this is useful if we have many servants that share the same adapter and do not want requests to be processed until after all the servants have been instantiated.)
- Finally, we call
waitForShutdown. This call suspends the calling thread until the server is shut down. (For now, we will simply interrupt the server on the command line when we no longer need it, which terminates the server immediately.)
We can compile the server code as follows:
Build the server project using "Build > Builder Server"
Build the server project using the dotnet
Write and Compile your Client
The client code, in
Client/Program.cs, looks very similar to the server.
Here it is in full:
Note that the overall code layout is the same as for the server: we use the same
catch blocks to deal with errors. The code in the
try block does the following:
- As for the server, we initialize the Ice run time by calling
- The next step is to obtain a proxy for the remote printer. We create a proxy by calling
stringToProxyon the communicator, with the string
"SimplePrinter:default -p 10000". Note that the string contains the object identity and the port number that were used by the server. (Obviously, hard-coding object identities and port numbers into our applications is a bad idea, but it will do for now; we will see more architecturally sound ways of doing this when we discuss IceGrid.
- The proxy returned by
stringToProxyis of type
Ice.ObjectPrx, which is at the root of the inheritance tree for interfaces. But to actually talk to our printer, we need a proxy for a
Printerinterface, not an
Objectinterface. To do this, we need to do a down-cast by calling
PrinterPrxHelper.checkedCast. A checked cast sends a message to the server, effectively asking "is this a proxy for a
Printerinterface?" If so, the call returns a proxy of type
Demo::Printer; otherwise, if the proxy denotes an interface of some other type, the call returns null.
- We test that the down-cast succeeded and, if not, throw an error message that terminates the client.
- We now have a live proxy in our address space and can call the
printStringmethod, passing it the time-honored
"Hello World!"string. The server prints that string on its terminal.
The client's project is just like the server's project shown earlier.
Build the client project using "Build > Builder Client"
Build the client project using dotnet
Run your Client and Server
To run client and server, we first start the server in a separate window:
At this point, we won't see anything because the server simply waits for a client to connect to it. We run the client in a different window:
The client runs and exits without producing any output; however, in the server window, we see the
"Hello World!" that is produced by the printer. To get rid of the server, we just interrupt it on the command line for now.
If anything goes wrong, the client will print an error message. For example, if we run the client without having first started the server, we get something like the following: