Hi Vlad,

>> Is that possible to implement something like a stateful web-server
>> with ACE?

Sure.

>> Its work could be described the following way:
>>
>> - As long as a thread-pool there is a pool of allocated handler objects,
>> which could be spare or used.
>> - Spare handler objects lie somewhere in memory, used ones do their work
>> in threads - one thread per one object.

Right.

>> - Acceptor waits for a connection on the specified TCP port or unix socket.
>> - When a connection arrives, Acceptor uses programmer-redefined routine
>> to check its conformity to one of the spare Handler objects.

Right, you could do this as follows:

1. Derive a class from ACE_Acceptor called something like Cached_Acceptor
2. Make the Cached_Acceptor::make_svc_handler() hook method a no-op
3. Make the Cached_Acceptor::accept_svc_handler() hook method do the
following:

>> If the conformity could not be found, the request is considered
>> "general". The conformity is usually checked by looking into the
>> data received from client.
>> - Once the conformity is found, the appropriate Handler object becomes
>> "used", and its handle_input() is called in a separate thread. If
>> there're no spare threads at the moment, an error message is returned to
>> the client.

>> - Object's handle_input() deals with the request. After that the object
>> isn't destroyed, but becomes spare again. Its thread therefore also
>> becomes spare.
>>
>> - Spare object are destroyed after a request timeout.

You can use ACE_Reactor::schedule_timer() and
ACE_Reactor::cancel_timer() to do this.

>> - There're also "general" handler objects, which are never destroyed, and
>> they handle "general" requests.
>>
>> I couldn't find the description of such a behaivor in ACE docs. But
>> implementing all this from scratch looks like reinventing the wheel.

It should be pretty trivial to do this with ACE_Acceptor.

Take care,

Doug
--
Dr. Douglas C. Schmidt, Associate Professor TEL: (949) 824-1901
Dept of Electrical & Computer Engineering FAX: (949) 824-2321
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