On Oct 10, 3:54 am, Markus <markus.hofm...@gmail.com> wrote:
> Hi Robert,
>
> maybe I must tell you a little bit more about my motivation.
>
> I have to do a presentation about APIs. I want to show APIs in stack
> programming. I want to show my colleges that a SAP (Service Acces
> Point) does not change the behaviour of a stack if it is correct
> programmed. Unfortenately everthing what I say I have to demonstrate.
> To reach my aim I was thinking that I show them that I add a SAP
> between IP and TCP layer under Linux. At the moment I am not really
> sure if this approach is a good one.
>
> They do not have the background knowledge of IP/TCP.
>
> I will take a look in socket progamming but I was thinking it is
> easier.


SAPs are an OSI concept and don't really apply to TCP/IP, and although
something performs a conceptually similar function in TCP/IP, it's
rather more ad-hoc. Nor are the layers really as separable as they
were (hoped for) in OSI. In some systems some form of "raw socket"
can be used to implement a transport on top of IP by applications, in
other systems such extension have to be done within the protocol stack.