Re: [boost] Re: [sockets] layers concept

From: Iain Hanson (Iain.Hanson_at_[hidden])
Date: 2005-04-26 07:29:57

On Tue, 2005-04-26 at 13:54 +0300, Boris wrote:
> Iain K. Hanson wrote:
> > Hi
> >
> > I created the layers concept for the  C++ Networking boost library.
> >
> > The layers I defined are:
> >
> > Layer 1 :- Light weight wrappers arround predominantl BSD socket
> > concepts.
> >
> > Layer 2 :- Acceptor, Connector, Reactor, and Svc_Handler concepts ala
> > ACE.
> >
> > Layer 3 :- An optional iostreams interface if desirable?
> >
> > Layer 4:- Applications layer - includes ftp, telent, http/s And user
> > applications
> 
> Is layer a package or a level of abstraction? I ask as I wonder if eg. layer 
> 3 is based on layer 2?

Not having done much work on iostreams for sockets I thought it would be
a little of both but I was not sure. I saw it as a higher layer
abstraction that had greater easy of use but probably less
flexibility/control.

Whereas Layer 2 has much greater flexibility and control but a greater
learning curve if you want/need the more advanced features.

> 
> If you look at http://www.highscore.de/boost/net/packages.png I put the 
> packages "ace" (your layer 2) and "iostream" (your layer 3) both in layer 1 
> because they don't necessarily depend on each other and I don't know if we 
> can tell which one of the two packages has a higher level of abstraction.
> 
> > [...]
> > Boris has also been atempting bto model Layer 1 but keeps calling
> > itlayer 0.
> 
> Hey, everyone called it level 0! :-)
> 
> > we need a common nomenclture or confusion will reign.
> 
> That's why I added the link to the package structure at 
> http://www.highscore.de/boost/net/packages.png everywhere to make sure we 
> talk about the same. It's quite similar to your layers concept except that 
> you created new application layer.

There has always been a need for standard applications protocols such as
FTP, Telnet, SMTP, HTTP, etc. But Beman Dawes wrote a set of
requirements for a socket library that said something like sockets are a
chapter in the book no the whole book. He meant to limit the scope of a
socket library so that it might actual get finished. I refined that idea
by comming up with my layers which we've been using  for the last 3 or 4
years.

Thats why I'm objecting to you subtracting 1 from the layer numbers.

/ikh