Remoting: Inter object communication. - C# Discussion Boards

Remoting: Inter object communication.

3-Dec-02 7:40

Having just read Liong's article about using the Observer pattern for a chat server, I don't think that this pattern is appropriate for a situation involving remoting. After all, the GoF patterns were all about object interactions within an app.

Other than the Wiki (http://c2.com/cgi-bin/wiki[^]) which does my head in trying to find anything sensible on it Dead | X|

, does anyone know of a catalogue of design patterns? E.g. some that apply to Remoting situations, others applying to other problem domains, etc.

Re: Design Patterns

Chris Austin3-Dec-02 10:03

Chris Austin

3-Dec-02 10:03

John,

I have some links on C# application of design patterns.
http://www.dofactory.com/patterns/Patterns.aspx[^]http://www.clipcode.net/components/snippets.htm[^]http://msdn.microsoft.com/msdnmag/issues/01/07/patterns/default.aspx[^]
I'm not sure if these will help you out with remoting as they seem to be mostly the GOF patterns.

I'd suggest checking out http://safari.oreilly.com/[^] and see if any of the Pattern books there are helpful.

Chris

Fill me with your knowledge, your wisdom, your coffee.

Re: Design Patterns

Jarrod Marshall4-Dec-02 7:42

Jarrod Marshall

4-Dec-02 7:42

There is a book called C# Design Patterns - A Tutorial that I have found really good.
It basically goes through the GoF patterns using C# examples.

Jarrod

Unicode Characters

Jassim Rahma3-Dec-02 6:25

Jassim Rahma

3-Dec-02 6:25

I have arabic text in textBox1 and I need to convert it to Unicode in textBox2? is there any easy & fast way to do it?

Many Thanks,
Jassim rahma

Re: Unicode Characters

Nick Parker3-Dec-02 8:08

Nick Parker

3-Dec-02 8:08

Take a look at the System.Text.UnicodeEncoding class. Smile | :)

Nick Parker

Not everything that can be counted counts, and not everything that counts can be counted. - Albert Einstein

Nathan Tran3-Dec-02 6:07

Nathan Tran

3-Dec-02 6:07

Hi,

I'm trying to code a chat server that supports tcp/udp connections as well as connections through remoting if the client is behind a firewall. How can I implement the server so that it will support both types of clients? The problem is that remoting requires the server object to be activated by the client but I need the server to be running all the time to support clients that are not using remoting to connect to it.

So the question is, how does an pre-existing object ( instantiated before the activation of the remoting object ) communicate with an object that is activated remotely by a client? The existing object and the activated object are in the same application domain ( I presume ).

This problem has been bugging me for days. I searched the net and there are a whole bunch of remoting tutorials, but none touches on this particular subject. Hopefully, some one here has a clue.

Nathan.

John Rayner3-Dec-02 8:04

3-Dec-02 8:04

Well, if I understand you correctly you are trying to get your chat server to send a message to the chat client. This message would probably be a new posting to the current discussion. Not having done this before, I'm probably a little out of my depth but here goes anyway ...

Firewalls are obviously going to limit a direct TCP / UDP connection from the server to the client so that option is out. That means that all communication has to be initiated by the chat client. So two options spring to mind:

Have the client poll the server every so often - you don't really get instant chat here and the closer you get to it (i.e. by polling more frequently) the more it clogs up your network and your server.
Have the client initiate an asynchronous request to the server which blocks until the server services it. Then, when a new message comes in to the server it hands the message off to the client. The client sees the response come back and immediately opens another async request.
You'll need a reliable way of identifying individual clients - if you're concerned about firewalls then I don't think IP address will be good enough. Probably each client would need to get an ID from the server and send that along with every request made.

I'd say the second is preferable from a network traffic and immediacy point of view, but it probably won't scale with the number of users (e.g. 5000 users = 5000 connections at the server waiting to be filled). But then who'd want to be in a discussion with 5000 people?!? It will also make the server quite complex to implement as it will have to keep track of which messages have been passed out to which clients. Also, if you have a very active discussion, the client may struggle to keep up - this could be avoided by each client having a number of outstanding requests to the server, but that would further limit the scalability.

Anybody else have any other ideas?

Nathan Tran3-Dec-02 10:41

Nathan Tran

3-Dec-02 10:41

John,

AFAIK .NET remoting supports serialization of client objects across channel by reference. I am banking on this reference to the client object to maintain a "connection" between server-client. To send a message back to the client I can simply call clientObjectRef.MsgServicingDelegate( Msg ); Indeed this solution will pose a scalability issue since, in affect, the client maintains an open channel with the server. Is this a wise solution? To what extent is the overhead required to maintain an open httpChannel? More importantly, how does the underlying framework acheives this feat?

Nathan.

John Rayner4-Dec-02 0:33

4-Dec-02 0:33

Well, I wrote a little test app to try what you are suggesting and it didn't work. I got the very long error message "

This remoting proxy has no channel sink which means either the server has no registered server channels that are listening, or this application has no suitable client channel to talk to the server.

". Hats off to MS for at least trying to make their error messages informative ... Wink | ;)

A little digging on the web revealed a sample chapter from a Wrox book (http://www.wrox.com/books/sample-chapters/SampleChapter_186100740x.pdf[^]) which discusses a similar problem. If you look on page 24 of the PDF you'll see that they set the client app with a Remoting channel in order for the server to communicate with the client.

Once I'd modified my test app in this way, everything worked. However, I very much doubt that this will work if there's a firewall in the middle of the connection (which was the problem we were discussing).

Nathan Tran4-Dec-02 6:59

Nathan Tran

4-Dec-02 6:59

Hi John,

For communicating across a firewall I believe you have to set the HttpChannel on the client side to port 80 or a port that is not blocked. I haven't tried this myself since I'm still coding the message/user handling routines for my chat server. If you have time on your hands could you verify this? Thanks.

Nathan.

John Rayner4-Dec-02 7:17

Converting Texbox.Text to int 32

4-Dec-02 7:17

It's not the port number that you've got to worry about. It's more the address translation and usual firewall rules base which are going to be issues. Firewalls, in general, don't allow incoming requests to an arbitrary machine protected by them, whatever the port number, unless they have been specifically configured to do so. It's quite usual for them to allow outgoing connections to any server on port 80, but that's a very different thing.

And no, I'm not going to setup a firewall with machines on both sides just so I can test something for you which I don't think will work anyway. Sorry mate, I'm not quite that helpful ...

MonthCalendar

rurko753-Dec-02 5:38

rurko75

3-Dec-02 5:38

Hallo
I have one problem with component MonthCalendar (C#).I need build calendar to my project but set for specific days different background color!!!Can you someone help me?

Robert

Re: MonthCalendar

kaschimer3-Dec-02 10:46

kaschimer

3-Dec-02 10:46

I am assuming ASP.NET here. I had a similar issue, and needed to add in data on certain days.

For the calendar control, there is an event called DayRender which allows you to inspect each day (e.Day) as it is rendered and do something with the cell (e.Cell) (color it, add controls, etc). You can specify a style and then apply the style to the cell that corresponds to the days you want to do something with.

If you have Visual Studio Help available:

ms-help://MS.VSCC/MS.MSDNVS/vbcon/html/vbtskcustomizingindividualdays.htm[^]

Otherwise, you can find it on MSDN:

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpguidnf/html/cptskcustomizingindividualdays.asp[^]

Hope this helps!

RabidK

Windows Messages

Sean Rock3-Dec-02 3:34

Sean Rock

3-Dec-02 3:34

Hello, I'm looking for any tutorials on windows messages in C#.NET. what i'm trying to do is look at the windows messages sent to any running application.

TIA

Re: Windows Messages

Jeff J3-Dec-02 15:28

Jeff J

3-Dec-02 15:28

You might not find anything like that relating to C#, since there is nothing new about messaging in .Net. Still the same old WndProc() function, and PreProcessMessage() much as in MFC/ATL. Pretty much anything you find for windows messaging in C/C++, will hold true for C# too.

Cheers

Re: Windows Messages

Sean Rock3-Dec-02 22:08

Sean Rock

3-Dec-02 22:08

yeah i kept looking but found nothing specific to c# or .net so have to use wndproc().

cheers.

djkno33-Dec-02 1:28

3-Dec-02 1:28

I have a dll I made and have a set property to accept an int. I would like to fill this property by using the textbox class in a form. I call the Convert.ToInt32
like this
property = Convert.ToInt32(TextBox.Text);
now I get a stack overflow in the dll at the

public int property
{
set {property = value;} //This throws the exeption
}

Am I calling everything correctly? Or am I missing somthing?

Rickard Andersson²⁰3-Dec-02 1:47

Rickard Andersson²⁰

3-Dec-02 1:47

djkno3 wrote:
public int property
{
set {property = value;} //This throws the exeption
}

You're assigning the value to the property itself which is wrong.
You'll need a member varible of type int, so change the code to this:

public int MyPropertyName
{
   set{ myMemberInt = value; }
}

Rickard Andersson@Suza Computing
C# and C++ programmer from SWEDEN!
UIN: 50302279
E-Mail: nikado@pc.nu
Speciality: I love C#, ASP.NET and C++!

djkno33-Dec-02 3:09

3-Dec-02 3:09

Thanks that was the problem. To get the value do I use the same variable eg return myMemberInt? It works like this but is it the correct way?

kaschimer3-Dec-02 4:01

kaschimer

3-Dec-02 4:01

To create the read/write property you want, you will want to create a get:

<br />
public int MyPropertyName<br />
{   <br />
    set{ myMemberInt = value; }<br />
    get{ return myMemberInt; }<br />
}<br />

RabidK

djkno33-Dec-02 4:50

3-Dec-02 4:50

thanks that's what I have I was just wondering if it was correct Big Grin | :-D

or if I was just getting the right answer by chance and have a nice bug pop up later because of it. thanks

Pyt3-Dec-02 1:47

Pyt

3-Dec-02 1:47

It looks like the value entered in the TextBox is too big for an Int32.

MDSN:
The Int32 value type represents signed integers with values ranging from negative 2,147,483,648 through positive 2,147,483,647.

Pyt

Pyt.

djkno33-Dec-02 3:12