Browse Prior Art Database

Dynamic Data Exchange Time Management Algorithm

IP.com Disclosure Number: IPCOM000114837D
Original Publication Date: 1995-Feb-01
Included in the Prior Art Database: 2005-Mar-29
Document File: 2 page(s) / 65K

Publishing Venue

IBM

Related People

Nickolas, SE: AUTHOR [+2]

Abstract

There are many forms of communicating information between applications in OS/2*. One of the earliest mechanisms available as part of the OS/2 operating system was the Dynamic Data Exchange (DDE) protocol. Using this protocol, applications adhere to the protocol and acknowledge applications accessing data through their publicly available program identifiers. In this manner, text, graphics, and program unique data can be made available to other applications.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Dynamic Data Exchange Time Management Algorithm

      There are many forms of communicating information between
applications in OS/2*.  One of the earliest mechanisms available as
part of the OS/2 operating system was the Dynamic Data Exchange (DDE)
protocol.  Using this protocol, applications adhere to the protocol
and acknowledge applications accessing data through their publicly
available program identifiers.  In this manner, text, graphics, and
program unique data can be made available to other applications.

      The protocol follows the request-response paradigm.  In that
one application issues a request and the receiving application
responds by accepting or rejecting the request.  This activity is
managed between the two programs asynchronously.  In OS/2 this is
done through Presentation Manager* (PM) window messages.  Since this
is done asynchronously, the request-posting program must return to a
state where it can accept PM messages.

      This protocol does not provide a mechanism in the event a
response is not acknowledged.  Ideally, a mechanism for informing the
requester after a customizable amount of time has elapsed is
necessary.  Programmatically speaking, the request function call
should not return to the caller until the response is received or the
timeout occurs in order to synchronously indicate what occurred.
Languages such as BASIC require synchronous acknowledgement in this
manner.  Therefore, an algorithm is needed for creating a synchronous
DDE function which manages an asynchronous DDE event.

      This problem is solved in the Windows** platform by
implementing a polling loop which constantly peeks the queue to see
if the DDE response message is on the que...