.NET Remoting question

[Guest]

Hi,

I'm new to .NET remoting and there's something I'm having real trouble with.
Basically, I'd like to create a component that can act as a server and as a
client (can send messages and receive them in asynchronous mode).

Here's the situation just so you guys understand why I'm doing this (and
maybe so that you can provide me with other options):

I have an application that needs to save data to a remote database. The
DBAs don't allow direct modifications or insertions into the database for
security and other reasons. So, they built what we call here an INSERTION
SERVICE (IS). The application that wants to save to the db has to create an
XML file with the details of the changes and drop it on an FTP site for
processing. Problem is that files can be rejected for many reasons so we
would like to inform the user whether his changes have been done or not.
Since this is a very busy database, the changes are not necessarily done
immediately, the files are put in a priority queue.

So basically, once the changes have been made or not, we need to inform the
user in the App. We thought about building some kind of proxy that resides
between the application and the IS. The application would register itself to
the proxy everytime it sends a new file to the IS. Once the file has been
processed, the IS could send a message to the proxy that would dispatch it to
the App. So, the App would need to act as a client for the original
registration to the proxy and as a server for the reception of the final
message (vice-versa for the proxy).

There might be a better way of doing this but I don't see it. With basic
..NET Remoting, I could do it by having the client wait for the IS to answer
and then send that answer to the client but since I have no idea how long
that could take, It's not a good option.

Thanks a lot in advance for all your help,

Skip.

 

[Joep]

Sounds like something that typically calls for MSMQ although remoting is
also possible but if you are new to remoting MSMQ is much easier. Otherwise,
try Ingo Rammer's book on remoting a try.

 

[Richard Blewett [DevelopMentor]]

When the client submits work to the server, why not have them supply an interface to othemselves at the same time. So the remote method would look something like:

void Submit(string doc, INotifyClient);

and INotifyClient is implemented by the client and looks like this:

interface INotifyClient
{
void WorkCompletedSuccessfully();
void WorkInError(int errorcode);
}

or something like that. Now when teh work is enqueued for processing (Submit returns) the client cal get on with their own thing. The server enqueues not only the doc but, packaged with it, the interface to the client that submitted the work. When the work is dequeued it is processed and the client informed of the outcome via the interface. The only thing you will need to do in the client is create a Channel like this (doesn't matter which channel btw)

TcpChannel chan = new TcpChannel(0); // will set this up on a free port on the client
ChannelServices.RegisterChannel(chan);

The server doesn't need to know what port the client is listening on or where the client is *explicitly* as this information will be passed as part of the submit message as the interface is marshalled.

Two things to note:

1) the call from the server will come on a threadpool thread and so you have to be careful of multithreading issues.
2) This will have issues if there is a firewall in the network topography

Regards

Richard Blewett - DevelopMentor
http://staff.develop.com/richardb/weblog

nntp://news.microsoft.com/microsoft.public.dotnet.languages.csharp/<[email protected]>

Hi,

I'm new to .NET remoting and there's something I'm having real trouble with.
Basically, I'd like to create a component that can act as a server and as a
client (can send messages and receive them in asynchronous mode).

Here's the situation just so you guys understand why I'm doing this (and
maybe so that you can provide me with other options):

I have an application that needs to save data to a remote database. The
DBAs don't allow direct modifications or insertions into the database for
security and other reasons. So, they built what we call here an INSERTION
SERVICE (IS). The application that wants to save to the db has to create an
XML file with the details of the changes and drop it on an FTP site for
processing. Problem is that files can be rejected for many reasons so we
would like to inform the user whether his changes have been done or not.
Since this is a very busy database, the changes are not necessarily done
immediately, the files are put in a priority queue.

So basically, once the changes have been made or not, we need to inform the
user in the App. We thought about building some kind of proxy that resides
between the application and the IS. The application would register itself to
the proxy everytime it sends a new file to the IS. Once the file has been
processed, the IS could send a message to the proxy that would dispatch it to
the App. So, the App would need to act as a client for the original
registration to the proxy and as a server for the reception of the final
message (vice-versa for the proxy).

There might be a better way of doing this but I don't see it. With basic
.NET Remoting, I could do it by having the client wait for the IS to answer
and then send that answer to the client but since I have no idea how long
that could take, It's not a good option.

Thanks a lot in advance for all your help,

Skip.

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[microsoft.public.dotnet.languages.csharp]

 

[Guest]

Thanks Richard,

I finally had time to try what you suggested but I'm getting all sort of
exceptions because my classes and proprties are not serialized correctly
(that's my hypothesis).

Here's part of my code:

<THIS IS THE SHARED OBJECT CODE>
public interface IClient
{
void WorkCompleted(string msg);
}

public class RemoteMessage : MarshalByRefObject
{
public RemoteMessage()
{
ClientQueue = new ArrayList();
}


public void SetClient(string xmlFileName, IClient client)
{
ClientQueue.Add(new ClientInfo(xmlFileName, client));
}

public void SetMessage(string xmlFileName, string msg)
{
//Find the corresponding client according to its XML file (unique)
//and return a message through its client interface (asynchonous).
//Finally delete the entry for this client in the collection.
int i;

for (i=ClientQueue.Count-1; i>0; i--)
if (ClientQueue.ToString().Equals(xmlFileName))
{
ClientInfo obj = (ClientInfo) ClientQueue;
obj.GetClient.WorkCompleted(msg);
ClientQueue.RemoveAt(i);
//Could stop but for debugging purposes, we will continue in case object
is there more than once
}
}

private System.Collections.ArrayList ClientQueue;
}

<THIS IS THE CLIENT CODE>
class Client : IClient
{
RemoteMessage server;
HttpChannel channel;

public Client()
{
Console.WriteLine("***** Client started *****");
Console.WriteLine("Hit ENTER to end.");
}

public void Register()
{
channel = new HttpChannel();
ChannelServices.RegisterChannel(channel);

object remoteObj = Activator.GetObject(
typeof(SI_Remoting.RemoteMessage),
"http://localhost:32469/RemoteServer.soap");

server = (RemoteMessage) remoteObj;

}

public void RegisterNewMsg(string xml)
{
server.SetClient(xml, this);
}

//this will be called by the SI
public void UnregisterMsg(string xml, string msg)
{
server.SetMessage(xml, msg);
}


public void WorkCompleted(string msg)
{
//Return the message sent to DVS.
Console.WriteLine("Received message: {0}", msg);
}

[STAThread]
static void Main(string[] args)
{
Client client = new Client();

client.Register();
client.RegisterNewMsg("xml1");
//client.UnregisterMsg("xml1", "xml has been processed.");

Console.ReadLine();
}
}

I have no idea what to try next.

Any help would be greatly appreciated.

Thanks, Skip.