[usocket-devel] "experimental-udp" branch merged into usocket trunk

[Elliott Slaughter]

One more request:

Is there any way of having a timeout on socket-receive? Or at least have
some way of checking whether there is any data waiting (so I don't have to
block while waiting for packets to arrive)?

Thanks.

On Wed, Jan 13, 2010 at 6:02 PM, Elliott Slaughter <
elliottslaughter at gmail.com> wrote:

> On Thu, Jan 7, 2010 at 11:02 AM, Chun Tian (binghe) <binghe.lisp at gmail.com
> > wrote:
>
>> Hi, usocket users
>>
>> I want to mention, the "experimental-udp" branch has been merged into
>> usocket trunk.
>>
>> Changed API:
>>
>> [SOCKET-CONNECT]
>>
>> SOCKET-CONNECT now has a new keyword argument PROTOCOL with default
>> :STREAM as tcp, but if you set it to :DATAGRAM, this means you're creating a
>> UDP socket.
>>
>> Be different with TCP socket, a UDP socket can be connected or
>> unconnected. The method to create a unconnected UDP socket is to leave the
>> first two argument of SOCKET-CONNECT as NIL:
>>
>>        (SOCKET-CONNECT NIL NIL :PROTOCOL :DATAGRAM)
>>
>
> It isn't clear to me how unconnected UDP sockets are to be used, since the
> host and port are unspecified. I would expect that most users would always
> want to use connected sockets.
>
> Creating a server UDP socket which "listen" on local address is also
>> supported, the method is to set additional keyword arguments: LOCAL-HOST and
>> LOCAL-PORT:
>>
>>        (SOCKET-CONNECT NIL NIL :PROTOCOL :DATAGRAM :LOCAL-HOST nil
>> :LOCAL-PORT 10000)
>>
>> Notice: the "nil" as LOCAL-HOST means that you listen on wildcard address
>> "0.0.0.0", same effect as *wildcard-host*.
>>
>> [SOCKET-SEND]
>>
>> Syntax: SOCKET-SEND usocket buffer length &key host port
>>
>> SOCKET-SEND is used for sending packets through a UDP usocket, the
>> "buffer" arguments usually need to be a vector of (unsigned-byte 8).
>>
>
> What does the return value of socket-send mean?
>
> [SOCKET-RECEIVE]
>>
>> Syntax: SOCKET-RECEIVE usocket buffer length &key
>>
>> SOCKET-RECEIVE is used for receiving packets from a UDP usocket, the
>> "buffer" argument will be filled into received data, but if you give NIL,
>> this function will create a new buffer object for holding received data, the
>> default buffer length will be 65536 which defined as a constant
>> +max-datagram-packet-size+.
>>
>
> The constant +max-datagram-packet-size+ is not exported from the usocket
> package, and seems to be unbound when I try to access it.
>
> When I try to call socket-receive with both buffer and length nil, it
> complains that they can't both be nil. I was under the impression that if I
> left both as nil then it would create a buffer of size
> +max-datagram-packet-size+.
>
> Notice: if you use this function to receive data from a unconnected socket,
>> you may need to know where the data from. Actually, SOCKET-RECEIVE will
>> return multiple values, the exact number is 4:
>>
>>        1. buffer (the same object as the "buffer" argument if it's not NIL
>> when calling SOCKET-RECEIVE)
>>        2. size (how many bytes received)
>>        3. host (which address this data from)
>>        4. port (which IP port this data from)
>>
>> [SOCKET-SERVER]
>>
>> Syntax: SOCKET-SERVER host port function &optional arguments &key (timeout
>> 1) (max-buffer-size +max-datagram-packet-size+)
>>
>> SOCKET-SERVER can create a simple single-threaded UDP server. This
>> function is a indefinite loop, so you should create it in a new created
>> thread using your platform's thread API.
>>
>> The arguments "function" and "arguments" controls your UDP server's
>> function, declaration of this function:
>>
>>        function (data &optional arguments)
>>
>> This function will work like a filter, received data in, and return data
>> send out. For example, a UDP Echo server can be defined in following code:
>>
>>        (defun echo-function (data)
>>          data)
>>
>> And following code created this server on local port 10000:
>>
>>        (socket-server nil 10000 #'echo-function)
>>
>> What if your filter function need to know where the data from? Get this
>> information from two special variables: *REMOTE-HOST* and *REMOTE-PORT*.
>>
>> The argument "timeout" can control the loop frequency, usually no need to
>> modify. Read "server.lisp" for details.
>>
>>
>> The last important thing USOCKET user need to know: UDP support haven't
>> been done on all CL platforms.
>>
>> Current finished supported CL platforms:
>>
>> * CMUCL
>> * SBCL and ECL (not on win32)
>> * Allegro CL
>> * LispWorks (not on win32)
>> * SCL
>> * Clozure CL
>>
>> Unfinished CL platforms:
>>
>> * CLISP
>> * Armedbear Common Lisp (ABCL)
>> * Macintosh Common Lisp (MCL/RMCL)
>>
>> And the USOCKET-UDP [1] project will be just closed. The function
>> SOCKET-SYNC in that project will not be merged into USOCKET trunk because of
>> less useful in most cases.
>>
>> Bug reports, optimization suggestions, patches on unfinished platforms are
>> all welcome. Thank you for using USOCKET project.
>>
>
> Thanks for working on this. I'm eagerly awaiting full compatibility win32
> implementations.
>
> --
> Elliott Slaughter
>
> "Don't worry about what anybody else is going to do. The best way to
> predict the future is to invent it." - Alan Kay
>



-- 
Elliott Slaughter

"Don't worry about what anybody else is going to do. The best way to predict
the future is to invent it." - Alan Kay
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