DotNetOrb.OMG 1.0.2

DotNetOrb CORBA Standard Library for C#

Welcome to the DotNetOrb CORBA Standard Library for C#!

This library is designed to provide seamless integration with the Common Object Request Broker Architecture (CORBA) standard in your C# applications.

With CORBA, you can easily communicate between distributed objects, regardless of the programming languages they are implemented in, making it a powerful tool for building robust and interoperable systems.

It's partially based on JacOrb with an idl compiler built from scratch for C# and the communication layer built on top of DotNetty for performance.

How to Contribute

We welcome contributions from the community to help improve and expand the functionality of DotNetOrb.

If you encounter any issues or have suggestions for new features, please feel free to open an issue or submit a pull request.

License

This project is licensed under the MIT License - see the LICENSE file for details.

Installation

You can install DotNetOrb via NuGet:

Package Manager Console

Install-Package DotNetOrb.Core

.NET CLI

dotnet add package DotNetOrb.Core

You can also install DotNetOrb IdlCompiler as a global tool

.NET CLI

dotnet tool install --global DotNetOrb.IdlCompiler

Configuration

Configuration options can be set in different ways:

• as properties passed as arguments to ORB.Init() function.
• as command line properties
• as environment variables
• in configuration files (appsettings.json)

The ORBid property can only be set with the first two options. The default ORBid is "DotNetOrb". The settings in the configuration file must be included within a section with the ORBid name. So for example an orb initialized with

-ORBid TestORB

the configuration file would be:

  "TestORB": {
      "OAIAddr": "myhost",
      "OAPort": 3001
  }

Listen endpoints

To supply an explicit listener protocol and address the following properties can be used:

Alternatively, you can use the command-line option

-ORBListenEndpoints iiop://myhost:3001

Multiple endpoints can be specified by delimiting endpoints with a semi-colon, or using multiple -ORBListenEndpoints options. For ssl endpoints use the form:

-ORBListenEndpoints iiop://myhost:3001/ssl_port:443

Initial references

Initial references are object references thar are available to CORBA application through orb.ResolveInitialReferences method. Property|Description|Example| |--|--|--| |ORBInitRef.<service>|service will be resolved to the url specified|file:///tmp/tao imr locator.ior|

The url could be directly an IOR string or point to an http server or file.

Codesets

Currently supported codesets:

• us-ascii
• macintosh
• iso-8859-1
• iso-8859-15
• utf-8
• utf-16
• UCS2

Security

IIOP/SSL parameters (numbers are hex values, without the leading 0x):

• NoProtection = 1
• EstablishTrustInClient = 40
• EstablishTrustInTarget = 20
• Mutual authentication = 60

POA Configuration

Implementation Repository

Logging

To configure logging you must implement DotNetOrb.Core.ILogger interface and provide the class name in the following property: |Property|Description|Example| |--|--|--| |DotNetOrb.Logger|Full name of the class that does the actual logging|MyServer.Logger

Getting started

The general process of developing a CORBA application involves the following steps:

1. Write an IDL specification.
2. Compile this specification to generate c# classes (interfaces, classes, helpers, stubs and skeletons).
3. Write an implementation for the interface generated in previous step.
4. Write a main class thar instantiates the server implementation and registers it with the ORB.
5. Write a client class that retrieves a reference to the server object and makes remote invocations.

As an example we will develop a simple chat application with the following idl file

chat.idl

module Chat
{
	exception MaxUsersReached
	{
		long numUsers;
	};

	exception UserNotAuthenticated
	{		
	};

	enum ColorEnum {
		Default,
		Green,
		Yellow,
		Red
	};

	struct Message
	{
		string from;
		ColorEnum color;
		wstring text;
	};

	interface Client {
		readonly attribute string Name;
		void SendMessage(in Message msg);
	};

	interface Server {
		readonly attribute string Name;
		boolean RegisterUser(in Client clientRef, out long sessionId) raises(MaxUsersReached);
		void UnregisterUser(in long sessionId);
		void BroadcastMessage(in long sessionId, in Message msg) raises(UserNotAuthenticated);
	};
};

To compile the idl we use the DotNetOrb.IdlCompiler tool:

IdlCompiler usage:
  DotNetOrb.IdlCompiler [options] [files]

Creates C# source code for the OMG IDL definition files.
files: idl files containg OMG IDL definitions.

options are:
-h or -help                              help
-i directory                             additional directories for idl file includes (multiple -i allowed)
-o directory                             output directory. Default is .\
-d define                                defines a preprocessor symbol
-sequence_type [array | list]            type of sequence fields: array (default) or List
-ami                                     generate async methods
-naming_scheme [dotnet | idl]            respect original idl names or convert to dotnet naming (default)

DotNerOrb.IdlCompiler -o .\compiled_idls chat.idl

To provide an implementation of the functionality promised by the interface we should implement

ServerPOA

public class ChatServerImpl : ServerPOA
{
    private int currentSessionId = 1;
    private int maxUsers = 5;

    private Dictionary<int, IClient> registeredClients = new Dictionary<int, IClient> ();

    public override string Name { get => "My chat server"; }

    public override void BroadcastMessage(int sessionId, Message message)
    {
        if (!registeredClients.ContainsKey(sessionId))
        {
            throw new UserNotAuthenticated();
        }            
        foreach (var kvp in registeredClients)
        {
            if (kvp.Key != sessionId)
            {
                kvp.Value.SendMessage(message);
            }
        }
    }

    public override bool RegisterUser(IClient clientRef, out int sessionId)
    {
        if (registeredClients.Count >= maxUsers)
        {
            throw new MaxUsersReached(maxUsers);
        }
        sessionId = currentSessionId;
        registeredClients.Add(currentSessionId++ , clientRef);
        return true;
    }

    public override void UnregisterUser(int sessionId)
    {
        if (registeredClients.ContainsKey(sessionId))
        {
            registeredClients.Remove(sessionId);
        }
    }
}

ClientPOA

public class ChatClientImpl : ClientPOA
{
    private string name;
    public override string Name
    {
        get
        {
            return name;
        }
    }
    public ChatClientImpl(string name) 
    { 
        this.name = name;
    }

    public override void SendMessage(Message msg)
    {
        switch (msg.Color)
        {
            case ColorEnum.Red:
                Console.ForegroundColor = ConsoleColor.Red;
                break;
            case ColorEnum.Green:
                Console.ForegroundColor = ConsoleColor.Green;
                break;
            case ColorEnum.Yellow:
                Console.ForegroundColor = ConsoleColor.Yellow;
                break;
        }
        Console.WriteLine();
        Console.WriteLine(msg.From + ">" + msg.Text);
        Console.ResetColor();
        Console.Write($"{name}>");
    }
}

To run the server we should initialize the orb and obtain a reference to the object adapter (the POA) and activate it to start processing incoming requests. We should also create an instance of our server class and make its object reference available, in this case with a simple file.

ORB orb = (ORB)ORB.Init();
var poa = POAHelper.Narrow(orb.ResolveInitialReferences("RootPOA"));
poa.ThePOAManager.Activate();

CORBA.IObject o = poa.ServantToReference(new ChatServerImpl());
var ior = orb.ObjectToString(o);
using (StreamWriter writer = new StreamWriter("C:\\temp\\chatServer.ior"))
{
    writer.WriteLine(ior);
}
orb.Run();

The client will do something similar, and also obtain the server ior from the file to connect to it.

ORB orb = (ORB)ORB.Init();
var poa = POAHelper.Narrow(orb.ResolveInitialReferences("RootPOA"));
poa.ThePOAManager.Activate();
var client = new ChatClientImpl("myclient");
CORBA.IObject o = poa.ServantToReference(client);
string serverIOR = File.ReadAllText("C:\\temp\\chatServer.ior");
var chatServer = ServerHelper.Narrow(orb.StringToObject(serverIOR));            
try
{
    if (chatServer.RegisterUser(client._This(orb), out int sessionId))
    {
        var message = new Message("myclient", ColorEnum.Green, "Hello!");
        chatServer.BroadcastMessage(sessionId, message);
        chatServer.UnregisterUser(sessionId);
    }
}
catch (MaxUsersReached) 
{
    //Max users reached
}            

For more info, please refer to the examples folder and JacORB documentation