Re: [boost] Socket concepts + definitions

From: Iain.Hanson_at_[hidden]
Date: 2001-07-27 13:18:38

     Local or remote
        I'm not sure but this may only be optional depending on whether the 
     system supports it i.e. unix domain sockets. They are on Unixes and 
     Mac's but not directly on Windows
     
     Protocol family
        raw
        IPv4
        IPv6
        ATM
        X25
        etc ...
     With the exception of raw, this identifies the network layer ( OSI 
     layer 3 ). raw gives access to the data link layer ( layer 2 ).
     
     Address Family
        IPv4
        IPv6
        X25
        NSAP family
        etc
     IPv4 and IPv6 only have a single addressing scheme. Other protocols 
     such as OSI Network layer identified as NSAP ( Network Service Access 
     Point ) have multiple ways of interpreting the address and can have 
     different length addresses dependant on the scheme.
     
     
     Active or Passive
     This is whether the server calls listen or connect
     
     Blocking or Non-Blocking
     When we call write or read on a socket, the call blocks until all the 
     data has been copied over into kernal space. If there is significantly 
     more data than there is buffer space in the kernal ( typically 64K 
     today ) then the write can block for a considerable period of time ).
     non-blocking calls return immeadiately if they would block and set 
     errno to EAGAIN
     
     Unicast or Multicast or Broadcast 
     Unicast is a transmission to a single other party i.e. point to point, 
     Multicast transmitts to a channel and multicast routers ensure that it 
     is only forwared to a subnet if clients have registered for the 
     channel. Broadcast means send it everywhere.
     
     Connected or Connectionless
     whether you need to establish a connection to the far end including 
     the allocation of resources ( some on route ) and at the far end 
     beforte you can transmitt or receive data.
     TCP is a connection oriented transport layer that runs on top of 
     connectionless IP. TP4 is a connectionless transport layer that can 
     run over either CONS or CLNS ( Connection Oriented Network Service and 
     Connection Less Network Service ).
     
     Datagram or Stream
     Whether the data ( from the user perspective ) arrives in packets or 
     as a byte stream.
     
     Reliable or Un-reliable
     un-reliable means the protocol can lose packets  without informing 
     you. Reliable means that the protocl will request re-transmission of a 
     lost packet without user/programmer intervention and if it can not get 
     the packet after a number of retries it will inform the user.
     
     Ordered or UnOrdered
     Whether the data can only arrive at the user in sequence or if it can 
     arrive out of sequence.
     
     support for out-of-band data
     This does not have to queue up in the buffers waiting to be sent, but 
     may be sent urgently.
     
     
     I guess I probably need to write a glossary and put it in the vault.
     
     BTW Beman, could you post the requirements that you came up with 
     please. Thanks.
     
     /ikh
     

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