sockets2 GenVoca layering for address

From: Iain.Hanson_at_[hidden]
Date: 2002-02-26 11:11:29

After N re-working I have finally come up with the following design
for an network & transport address.

socket address Feature Model

address                 :       address [ Representation ,
                                          Marshalling ,
                                          TransmissionType ,
                                          Location ]

Representation          :       sockaddr_in | sockaddr_in6 | SomeOther

Marshalling             :       NetworkByteOrder | LittleEndian | SomeOther
| None

TransmissionType        :       Unicast | Broadcast | Multicast

Location                :       Local | Remote

In practice, Representation would be a Protocol Traits class. 

Marshalling is, in every case I am aware of, NetworkByteOrder or None however 
the possible variation point allows for the future ( as the C socket API does as
well ).

The TransmissionType prevents the creation of a TCP socket with anything other 
than a Unicast address and could also validate the bit pattern within the 
address.

Location is relative to the current program or process. This is because you can 
only bind and listen on a local address and connect or accept from a remote 
address. Similarly with sendto and recvfrom.

This can be implemented using named template parameters and one layer for each 
of the four policies.

Design Notes

This class can only be constructed with strings in the dotted decimal format. 
I.e. "10.0.0.1" or possibly "10.0.0.1:12345". An address can not be created from
a hostname or DNS name. This is because the performance characteristics of DNS 
lookup are substancially slower, potentially involving a number of network and 
file accesses before returning. Therefore, for converting DNS names to addresses
and services to ports see resolver.

Constructors.

The default constructor and a constructor taking an already marshalled address 
will go in the lowest ( base ) layer. The rest of the Constructors should
be implemented in the marshall layer.

Implementation

To avoid having platform headers in the boost networking headers, I have 
created, for instance csocket.h as my implementation of socket.h and am in the 
process of doing this for cinet.h and all the other platform headers 
specifically used for sockets.

I'm currently working on the generator and hope to post it in a few days.

comments and questions appreciated.

/ikh

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