Oct 1980                             - 1 -


_  ____________
1  Introduction

     A  task has been implemented on the EMAS FEP system to facilitate access to
the ring name server. This task  handles  the  red  tape  of  the  ring  message
formats,  the  allocation  of  reply  ports and retrying the transmissions up to
three times if a reply is not received within 1 or 2 seconds.

     The name server task has name NAME and links in as task 15. The name server
task assumes that the FEP buffer manager task is  handling  the  allocation  and
deallocation  of  buffers. Messages to NAME should include a buffer which in the
most common case of a name lookup request will contain the name whose address is
required. The reply from  NAME  may  or  may  not  include  a  buffer  reference
depending  on  whether  a  reply was received or not from the name server on the
ring.

_  ______ _______
2  Buffer formats

     This section describes buffer formats in terms of IMP record  formats.  The
name server task does byte swapping within PDP11 words so that user programs may
use the natural PDP11 byte ordering.



     The buffer format for LOOKUP and REMOVENAME is



     ____________ LOOKF( ______ (LOOKF) ____ LINK,
     recordformat        record         name
     ___________ LEN, TYPE,
     byteinteger
     _______ A, P, C, R, F,
     integer
     ______ (61) NAME )
     string




     NAME is the only field that requires setting.





     The buffer format for ADDNAME is



     ____________ ADDF( ______ (ADDF) ____ LINK,
     recordformat       record        name
     ___________ LEN, TYPE,
     byteinteger
     _______ A, P, C, R, F,
     integer
     ___________ FLAGS, DUMMY,
     byteinteger
     _______ PORT, FUNCTION CODE,
     integer
     ______ (55) NAME )
     string














Oct 1980                             - 2 -


     For the meaning of FLAGS see the current name server documentation. PORT is
     the  basic  block  port  on  which an OPEN for this name should be sent and
     FUNCTION CODE is the code to be quoted on the open.



     The function REMOVEALL needs  to  give  a  buffer  for  NAME  to  send  the
     transmission, however the buffer need not contain any information.



The reply from the name server task will include a buffer pointer if a reply has
been  received from the name server on the ring. The format of this buffer is as
below.


     ____________ REPLYF( ______ (REPLYF) ____ LINK,
     recordformat         record          name
     ___________ LEN, TYPE,
     byteinteger
     _______ A, P, C, Z,
     integer
     _______ RETURN CODE,
     integer
     ___________ FLAGS, ADDRESS,
     byteinteger
     _______ PORT, FUNCTION CODE,
     integer
     ______ (55) RESTOFNAME )
     string




     Replies to all but look-up requests just contain RETURN CODE, this is  zero
     if  the operation was performed successfully, otherwise see the name server
     documentation. The other fields are set for a look-up request see the  name
     server  documentation for details. LEN is set to the length of REST OF NAME
     returned by the name server, if LEN is zero the  whole  of  the  string  is
     undefined.




_  ________ __ ___ ____ ____
3  Messages to and from NAME

          The  PON  message  to  NAME  requesting  a transfer to the name server
     should contain a function code in byte 2 and a buffer pointer  in  bytes  4
     and 5. The function code values are :-

          0   LOOKUP
          1   ADDNAME
          2   REMOVENAME
          3   REMOVEALL


     The  reply  from  NAME  will have a zero function code in byte 2 of the PON
message if a reply has been received. Bytes 4 and  5  will  contain  the  buffer
pointer.  This  buffer  needs  to  be returned to the buffer manager. A non-zero
function code indicates that  the  name  server  did  not  respond  after  three
retries. A suitable format for the PON record is:-











Oct 1980                             - 3 -


____________ PF( ___________ SERVICE, REPLY, FUNCTION, DUMMY,
recordformat     byteinteger
______ (LOOKF) ____ BUFFER,
record         name
_______ DUMMY2 )
integer

































































     University of Kent                     Computing Laboratory
       at Canterbury

     EMAS FEP name server task


     Date   Oct 1980










               ________                                         ____
               Contents                                         Page


               1  Introduction                                  1


               2  Buffer formats                                1


               3  Messages to and from NAME                     2






























Copyright University of Kent at Canterbury 1980