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UBF(A) - quick summary
2002-03-05

UBF(A) - quick summary

UBF(A) - specification

USF Encoding rules


    '...'       Push an constant onto the stack
                  (within an constant ' must be escaped (\')

     "..."      Push a string on the stack
                 (within a  string " must be escaped (\")

     Int ~...~  Push a binary on the stack (length int)

     `xxx`      Tag the top object on the stack as being type xxx
                 (within a  type ` must be escaped (\")

     %....%     Comment (skip)

     [-][0-9]*  Integer

     \s\n\r\t,  Ignore

     #          Push nil onto the stack

     &          Replace the two topmost entries on the stack
                with (cons X Y)

     {          Start of struct

     }          End of struct

     $          Return the top stack entry (the stack must only have
                ONE entry now)

     Control =  '"~%-0123456789{}#&$> (21 characters)

     >C         Pop the stack and store in register[C]

                C is any character except Control

     C          Push register[C] on the stack

Thus:

    'person'>p # {p,"Joe",123} & {p, 'fred', ~abc~} & $

Represents the UBF(B) term:

    [{person, "Joe", 123}, {person, fred, <>}].

Objects can be "semantically tagged" thus

    12345~....~ `jpeg`

Represents a 12345 byte object (contained between ~'s) that is of type jpeg. It is assumed that the application knows what this means.

    16~ahsjgdjagdjadjadg~ `md5`

Might be an MD5 checksum etc.

Servers and Introspection

  1. Servers only understand USF(A) formatted messages:
  2. Servers always respond to The message 'interface'$
  3. Client Server RCP is as follows {rpc, Term} -> {reply, Reply, NextServerState} All terms are UBF(A) encoded.
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