[Lazarus] Converting Pascal Client/Server application into Web Client?

[Michael Van Canneyt]

On Fri, 1 Oct 2010, Michael Schnell wrote:

> On 10/01/2010 01:25 PM, Michael Van Canneyt wrote:
>> 
>> 
>> 
>> Not sure what you mean by that.
> Sorry, but my old brain does not come up with the correct name of the method 
> (which I do know, though).  :(
>
> Here a (FastCGI) polling access is generated by the client java script, and 
> the CGI-Application does not respond so it hangs. The server responds 
> immediately to the still hanging request whenever an asynchronous 
> "server-event" arises. The client java script gets this response and acts 
> appropriately. There are some precautions that the requests does not hang so 
> long that the WebServer times out and kills it.

ExtJS has no such mechanism to my knowledge, but I'm not a reference.

> This is necessary to overcome the asymmetry of the http protocol.
>
> IMHO "Server-Events" are necessary to design a CGI program with some 
> complexity.

Well, I create seriously complex applications. No such mechanism was
necessary till now.

> Moreover "server-Internal-Events" like from Timers, serial or "direct" TCP/IP 
> communication, thread-notification, ... are very desirable and should be able 
> to fire "server-events" towards the client.

Why ? What could you possibly need to do that the server needs to contact
the client ? Everything you need can be programmed in the client, in my
experience.

You must be making some very weird applications that you need such
mechanisms :-)

The general rule here in my company is: 
Every call to the server is a call too much.

Let alone a 'persistent' connection...

Michael.