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MSc Course in Advanced Distributed Systems Session 2.2: Practical CORBA Programming. http://info.comp.lancs.ac.uk/msc/ads/index.htm. Resources. three problems: Echo, Time and Notifier http://www.comp.lancs.ac.uk/~leek/msc2004/ has problem specifications
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MSc Course in Advanced Distributed SystemsSession 2.2: Practical CORBA Programming http://info.comp.lancs.ac.uk/msc/ads/index.htm
Resources • three problems: Echo, Time and Notifier • http://www.comp.lancs.ac.uk/~leek/msc2004/has problem specifications • There are 3 problems, Echo, File and Chat • we will now look at the Echo example in some detail to get you started...
The Echo files (online) Echo.idl produces (mainly)... • EchoInterface.java. The IDL interface represented as a Java interface. • _EchoInterfaceImplBase.java. It implements the FileInterface.java interface • _EchoStub.java. The Stub. • Client.java. The Client Implementation • Server.java. The Server Implementation
Echo.idl // // Echo.idl // /// Put the interface in a module to avoid global namespace pollution module Exercise { // A very simple interface interface EchoServer { // Return the given string string echo(in string s); }; };
server.java 1 (of 2) // server.java, stringified object reference version import java.io.*; import org.omg.CORBA.*; class EchoServant extends _EchoImplBase { public String echo(String s) { return s; } } public class server { public static void main(String args[]) { try{ // create and initialize the ORB ORB orb = ORB.init(args, null); // create servant and register it with the ORB EchoServant echoRef = new EchoServant(); orb.connect(echoRef);
server.java 2 (of 2) // stringify the EchoRef and dump it in a file String str = orb.object_to_string(echoRef); String filename = System.getProperty("user.home")+ System.getProperty("file.separator")+"EchoIOR"; FileOutputStream fos = new FileOutputStream(filename); PrintStream ps = new PrintStream(fos); ps.print(str); ps.close(); // wait for invocations from clients java.lang.Object sync = new java.lang.Object(); synchronized (sync) { sync.wait(); } } catch (Exception e) { System.err.println("ERROR: " + e); e.printStackTrace(System.out); } } }
client.java 1 (of 2) // client.java, stringified object reference version import java.io.*; import org.omg.CORBA.*; public class client { public static void main(String args[]) { try{ // create and initialize the ORB ORB orb = ORB.init(args, null); // Get the stringified object reference and destringify it. String filename = System.getProperty("user.home")+ System.getProperty("file.separator")+"echoIOR"; BufferedReader br = new BufferedReader(new FileReader(filename));
client.cpp 2 (of 2) String ior = br.readLine(); org.omg.CORBA.Object obj = orb.string_to_object(ior); Echo echoRef = EchoHelper.narrow(obj); // call the Echo server object and print results String echo = echoRef.echo("Hello, World"); System.out.println(echo); } catch (Exception e) { System.out.println("ERROR : " + e) ; e.printStackTrace(System.out); } } }
Running the application Follow the instructions on the web site to download the pre-compiled classes. • running • run the server first: ‘java server’ • then run the client: ‘java server’