Re: Creating a simple windows messaging app


"Scott McPhillips [MVP]" <org-dot-mvps-at-scottmcp> wrote in message
news:%231zjOet4IHA.3484@xxxxxxxxxxxxxxxxxxxxxxx
"Nick Schultz" <nick.schultz@xxxxxxxx> wrote in message
news:eCclgps4IHA.4868@xxxxxxxxxxxxxxxxxxxxxxx
Hi there,

a broker app that receives packets from a canbus and pushes them out to
multiple applications.

there are two types of threads the broker will have: the main loop and
the "app" thread

The broker has a main loop that essentially sits and waits for two types
of messages:
-wm_canlib :
canlib notifies the broker by sending a wm_canlib message to a window
handle that I assign. the broker then takes the packet and then gives
each application thread a copy of the packet.
-(userdefined appregister) :
front end applications that want to receieve packets will broadcast
this message to get setup for receiving packets.
the main loop will then create a packet queue and spawns off a
appthread.

appThread responds to :
-WM_COPYDATA: (Sent from clientApp)
takes a packet sent from client app and sends it off on the bus
-QUEUE_READY: (Sent from mainloop)
gets notified from mainloop that it just put something in its queue.
the appthread will then empty the queue's contents, apply any filters on
it, and then send the packet off to its frontend app its responsible for.

so is there a good model to implement this scheme? there's only going to
be one main loop, and multiple appthreads (one for each registering app)
each thread is going to be needing the ability to send and receive
windows messages, including wm_copydata. How do I create the appthreads
so that it can send/receive messages?

Each appthread should be an instance of a class that you derive from
CWinThread. That gives it the ability to process incoming windows
messages. You start each appthread by calling AfxBeginThread. To receive
WM_COPYDATA each of these threads will need a window. It can be invisible
if its only purpose is to receive messages. You don't have to do anything
to give the thread an ability to send/post messages: Any thread can do
that.


I initially wanted to have all of this in the backgournd (invisible)
however I now think its a good idea to at least have a small window
indicating that the backend is on and that the user can start up their
front end applications. I can also have the ability to display raw data
packets as well.

Do all the display work in the main thread.

--
Scott McPhillips [VC++ MVP]


Since I just need a small dialog window , I'm using a dialog based mfc.
should I put the wm_canlib and appregister messages in the dialog's message
map? The handlers for these messages will then spawn off worker threads to
do what needs to get done.

and for the appthreads, I'll extend a CWinThread that has an member that
I'll create that extends CWin. I will then put the the messages that i
specified above for appThread in the CWin derived class?

is this correct?

Thanks,

Nick


.

Relevant Pages

  • Re: Creating a simple windows messaging app
    ... a broker app that receives packets from a canbus and pushes them out to ... each application thread a copy of the packet. ... appThread responds to: ... consists of putting the message into a queue to be sent to the bus (no ...
    (microsoft.public.vc.mfc)
  • Re: Creating a simple windows messaging app
    ... a broker app that receives packets from a canbus and pushes them out to ... each application thread a copy of the packet. ... appThread responds to: ... consists of putting the message into a queue to be sent to the bus (no ...
    (microsoft.public.vc.mfc)
  • Re: Creating a simple windows messaging app
    ... a broker app that receives packets from a canbus and pushes them out to ... each application thread a copy of the packet. ... appThread responds to: ... consists of putting the message into a queue to be sent to the bus (no ...
    (microsoft.public.vc.mfc)
  • Re: Creating a simple windows messaging app
    ... a broker app that receives packets from a canbus and pushes them out to ... each application thread a copy of the packet. ... appThread responds to: ... consists of putting the message into a queue to be sent to the bus (no WriteFile ...
    (microsoft.public.vc.mfc)
  • Re: Creating a simple windows messaging app
    ... a broker app that receives packets from a canbus and pushes them out to multiple applications. ... the broker then takes the packet and then gives each application thread a copy of the packet. ... the main loop will then create a packet queue and spawns off a appthread. ...
    (microsoft.public.vc.mfc)