Communication between HttpApplication that run on the same server

[Sherif ElMetainy]

Hello

I suggeest using xml web services. Remoting can be used too, and it can be
hosted in IIS, without the need for a separate process. Both solutions are
simple in deploymen, but the xml web service approach is simpler in
implementation.

Best regards,
Sherif

 

[[Gauthier]]

Hello,

I've a simple question:

On a server that run multiple asp.net HttpApplication, is there any way with
the asp.net framework to exchange data between different application?

I basically need to send message to a 'server wide' application from any
HttpApplication on the same server and obtain responses (wich may be simple
strings or streams for example), this 'server wide' application is also
HttpApplication.

If such feature doesn't exist, is this a place for remoting?

If this is a place for remoting did you have some hints on how I should host
the remoting server in my 'server wide' HttpApplication (keeping simple
deployment in mind)?

Thanks for any thoughts.

Gauthier

 

[Alvin Bruney]

Remoting is the replacement for all things DCOM. It will allow you, for
example, to push data thru one process boundary into another running process
which is what I think you are after. I'd suggest you start reading up before
you dive in because a couple issues can bite you. Look at ingo rammar's
book, it's the definitive work on remoting.

 

[[Gauthier]]

Thanks for your reply,

I'm more interested with remoting in place of xml web service because it's a
communication between 2 process that live on the same machine and also for
performances reason.

Could you tell me how IIS can host such remote process?

A solution I was thinking about was having a System.Diagnostics.Process
launched in Global.asax.cs within the Application_Start event, a console
process with standard I/O, so I could manage to get the ProcessId in other
HttpApplication and get a reference on that process, but I'm wondering if
remoting and all stuffs that come along wouldn't be a better solution.

I'm almost concerned with request concurrency (many apps that make request
on the 'server wide' application) and I imagine this could be an issue if I
use standard I/O of the process as the sole way to communicate.

So does the solution would be a dedicated process hosted in IIS that
communicate with my httpapps with a remoting client over tcp messages would
be the good one?

Will I have to investigate on threads issues or bottleneck to implement a
such process? (that's surely why xml web service and http communication
'simplify' a lot of stuffs)

Thanks for assistance & best regards

Gauthier

 

[Alvin Bruney]

you don't need to explicitly check for it. just make the call. the
application object and everthing related to it will either honor the request
if it is running or the runtime will first create and run the application,
initializing all the relevant objects before honoring the call.

 

[[Gauthier]]

Thanks, I've succesfully implemented a quick test and registered a
tcpchannel in my Global.asax.cs and it's work succesfully: I can call simple
methods from a remote application.

Now I've a simple question:
Is there an clean way to ensure that an httpapplication is allready started
(for my 'server wide' application), because my client applications need that
the httpapplication is started to make remote method calls, and it's fail if
the 'server wide' application is not started?

A simple solution I've think about is to make some 'activation httprequests'
on the 'server wide' application in my client applications, but that seams a
dirty solution if there is a more convinient way to autostart
httpapplications with iis or such thing.

Thanks for insight.

Gauthier

 

[[Gauthier]]

Hello,

I've missexplained my problem here:

My problem is that my 'server wide' HttpApplication is not allready started
in some case (for exemple just after saving the web.config of the
application).

Since I initialize my Channel in the Application_Start event, it's ok if the
application is allready started (for exemple just after a web request on
this application was made).

But i'm getting SocketException with the following message: 'No connection
could be made because the target machine actively refused it' when the
application is not allready started.

So the solution would be:
1: find a way to start the application when iis service is starting and
expecting that the application is not recycled is no request are made on it
after a period of time (is there such behavior in the asp.net framework?)

2: find a way to check that the channel exist (the 'server wide' application
is allready started) in my client remotefacade.

I've allready think about a possible implementation of the second solution
but the primmer seems simpler if it's possible and I don't know wether it is
or not.

Anyway I have to make such test (the second solution) to ensure that the
'server wide' application has registered the channel, for the sake of
robustness.

Thanks

Gauthier

 

[Alvin Bruney]

This isn't built in. You may write a service to do that but it's difficult
to do since the OS scheduler isn't guaranteed to start services in a
particular order. Better said, the service which start aren't guaranteed to
start in a particular order, so you aren't guaranteed that because iis
service starts before your service that iis will actually end up running
before your service resulting in errors on your part from this discrapency.

I suggest you go with option 2.