Opening HTTP channels

Pete Cordell pete at TECH-KNOW-WARE.COM
Wed Jul 28 12:06:22 EDT 1999


Espen,

I read your contribution about using HTTP to control services with great
interest.  I have been meaning to write such a proposal myself.

My approach differed from yours though.  I was primarily thinking of opening
HTTP channels using H.245.  (However, I can see the use for HTTP in the call
signalling, although I would prefer the signalling to be done using the
generic package scheme that I have proposed in APC-1631.)

My approach was to define a generic capability that contained a capability
identifier (any that you suggest would suffice), and also include a field to
specify a URL, a field to indicate re-load and optionally a numerical field
to indicate which browser window should display the page.

Only the capability identifier would be required in the TCS.  The other
fields are used when opening a channel.

As the HTTP channel is really opened from client to server, but it is the
server that is requesting the channel to be opened, I intended to use the
H.245 RequestMode message.  This would specify the HTTP channel using the
generic capability above.  It would specify the URL to use, or whether a
re-load was required.  If there were more than one page being displayed,
then it could indcate which window to display the data in.

As the time that an HTTP channel is open is really very small, and there was
really no convenient way to detect when a user had stopped looking at a
page, I decided to do away with OLC signalling as it made no sense.  Anyway,
at the end of the day it adds no value.

The resultant exchange would look something like (forgive my lack of drawing
skills):

-----TCS declaring HTTP support----->
        .
        . Other signalling
        .
<-----RequestMode( HTTP: URL=http://....) ---
------RequestModeAck ------>
------- HTTP Get ------>
<----- 200 OK --------

I think this is a cleaner way than using OLC signalling.  Specifying a URL
allows an HTTP service to be attached without originally setting out to do
that.

I hope this is clear,

Pete

=============================================
Pete Cordell
pete at tech-know-ware.com
=============================================



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