Calling local application from web app

[Durango2008]

Hello all,
I'm a bit of a newbie to this but I was wondering if I can call a local app.
via a web application. A friend suggested looking into ActiveX controls,
but I am not familiar with them. Also what other alternatives are there
beside using ActiveX? I read about using Flex and Applets but again I don't
know which would be my best option and what kind of security issues I may be
dealing with? If anyone can inform me or suggest a reference or book I
would appreciate it.
I would like to add I am working in a .Net 2.0 environment using VS2005 and
C# to build web forms.

Thanks for any information on this.
Durango.

 

[Peter Morris]

To do this the client would need to be listening on a port or something. In
my opinion it's not good practise. If your client can't reach your server
then the user can't use the app, by doing this you introduce the additional
problem that if the server can't reach the client then the app will only
work partially. It's very common in work environments that an Internet
server cannot reach the client because the client is likely to be behind
firewalls etc.

You should consider a different approach, such as

01: Client posts request
02: Server returns a job number
03: Client occasionally polls the server with the job number to check
progress

 

[Pavel Minaev]

Hello all,
I'm a bit of a newbie to this but I was wondering if I can call a local app.
via a web application.  A friend suggested looking into ActiveX controls,
but I am not familiar with them.  Also what other alternatives are there
beside using ActiveX? I read about using Flex and Applets but again I don't
know which would be my best option and what kind of security issues I may be
dealing with?  If anyone can inform me or suggest a reference or book I
would appreciate it.

What do you mean by "web application calling a local application",
even? Do you mean accessing client environment from within the HTML
page when it's rendered on the client? Or do you mean calling local
apps installed on the server on which your Web application is
deployed?

Since you mention ActiveX, I think it's the former. In which case
that's really the only alternative (and it is precisely because
ActiveX allows for such dangerous things, it is widely frowned upon).
You can also host a Windows Forms control in a browser.

Anyway, any more specific advice would depend on what _exactly_ you
are trying to do.

 

[Arne Vajhøj]

I'm a bit of a newbie to this but I was wondering if I can call a local app.
via a web application. A friend suggested looking into ActiveX controls,
but I am not familiar with them. Also what other alternatives are there
beside using ActiveX? I read about using Flex and Applets but again I don't
know which would be my best option and what kind of security issues I may be
dealing with? If anyone can inform me or suggest a reference or book I
would appreciate it.
I would like to add I am working in a .Net 2.0 environment using VS2005 and
C# to build web forms.

You want the web app to update the client ("push") ?

Options are:
1) emulate push via poll (some AJAX style JavaScript can be pretty good
for that purpose)
2) true push via a socket connection

#2 requires something like Java Applet, Flex or a custom ActiveX.

I would suggest one of the two first because (hopefully) no one
will install an ActiveX from an unknown source.

If client establishes connection you will need to have the ability
to run a real server (besides IIS and ASP.NET).

If server established connection, then it will not work with
client firewalls.

My recommendation would be to poll via JavaScript - it is by far the
most safe way.

(it does not scale that well, but my assumption is that you are
not coding for 10000 concurrent users)

Arne