Browse Prior Art Database

Multiple Threads to Implement Dual-Mode Operation for Person-to-Person Communication

IP.com Disclosure Number: IPCOM000104943D
Original Publication Date: 1993-Jun-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 4 page(s) / 142K

Publishing Venue

IBM

Related People

Baldwin, TJ: AUTHOR [+5]

Abstract

Disclosed is a scheme for implementing Person-to-Person communications over communication links of different types (e.g., LAN, Async, ISDN), in which only point-to-point connection is required (i.e., only two people can be in communication over one type of communication link). Multiple threads and semaphores are used to implement the scheme which allows the workstation to return various conditions to make the system appear like a standard telephone, with conditions such as "Engaged" and "Number not available".

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 45% of the total text.

Multiple Threads to Implement Dual-Mode Operation for Person-to-Person Communication

      Disclosed is a scheme for implementing Person-to-Person
communications over communication links of different types (e.g.,
LAN, Async, ISDN), in which only point-to-point connection is
required (i.e., only two people can be in communication over one type
of communication link).  Multiple threads and semaphores are used to
implement the scheme which allows the workstation to return various
conditions to make the system appear like a standard telephone, with
conditions such as "Engaged" and "Number not available".

      Person-to-Person conferencing (P2P) represents the convergence
of high performance communication channels (e.g., LAN, ISDN) with
advanced workstation and multi-media technologies (e.g., video
compression), to provide interactive communication of data, voice and
video between desktop workstations.  Like teleconferencing, it
permits collaboration without the users having to be in the same
place at the same time.

      Some P2P software only supports point-to-point operation (i.e.,
only two people are permitted in the call at any one point in time).
The communication between two P2P workstations may be over any type
of communication link, such as ISDN, LAN or Async.  Although each
workstation only sees one type of communication link, the
communication channel may be over a variety of different link types
used as bridges, routers and gateways.  Furthermore, a particular P2P
workstation may support more than one connection type such that an
incoming call can be received on either ISDN or LAN.

      Person-to-Person/2 uses the telephone metaphor for setting up
calls between two workstations both running P2P.  Unfortunately, the
base protocols of NETBIOS (and hence ISDNBIOS) do not mirror this
metaphor accurately so another protocol layer has had to be
implemented above NETBIOS to accurately reflect the telephone
metaphor.

      The area needing enhancement is that of "Number Unobtainable"
and "Engaged".  Furthermore by extending this protocol it is possible
to inform a caller when the callee has "Barred" and "Rejected" the
call so that these responses are not confused with "Engaged" and "No
Answer" as they would be in the standard telephone metaphor.  Thus
the caller might see any of the following responses when trying to
establish a call:

1.  "No Answer",  2.  "Engaged",  3.  "Call Rejected",  4.  "Barred",
5.  "Number Unobtainable",  6.  "Call Accepted",  7.  "Call
Auto-accepted".

The figure shows a block diagram of the call setup subsystem of P2P.
This should be referred to when reading the following description.
Note that in the description '(n)' refers to components of the
subsystem block diagram.

      Three main CPU threads are used to implement the call subsystem
(for two incoming call types).  These are:  1.  The ISDN thread (1),
2.  The LAN thread (2),  3.  The main thread (3).

  ...