PACE Abstract

PACE is a POSIX compliant middleware library that was written to allow developers to use one common programming API to access POSIX semantics across multiple, different operating systems, some of which are not currently POSIX compliant.

PACE is part of the open source ACE+TAO library/framework and its implementation was initiated in response to the RT DII COE project at BOEING that specifically targeted operating systems NT4 SP6, LynxOS 3.1.0a and SunOS 5.8. The RT DII COE project wants to build a Mission Application Independent programming framework described as an architecture, an approach, a collection of reusable software, a software infrastructure and a set of guidelines and standards. The proposed framework consists of three layers: the kernel, the data exchange layer and common Support Applications.

Such an ideal framework demands a strong, robust infrastructure and as such, ACE+TAO was chosen to be part of this project. ACE is the TAO developers API, essentially making TAO platform independent (or dependent on which platform ACE is ported to). As such, ACE provides very high level abstractions and key pattern techniques but handles different platforms, especially non-POSIX platforms, on a case-by-case basis (Win32 and VXWorks are two good examples).

PACE was born to abstract support for current and additional non-POSIX platforms away from ACE, thus, becoming an API for ACE developers to write to. Initial PACE support was limited to the previously mentioned DII COE platforms. Funding is now available to PACE to more of the platforms ACE supports, potentially encapsulating all of the platforms ACE currently supports. This will help separate the concerns of the current ACE+TAO framework so that:

• (PACE = low level, operating system middleware)
• (ACE = high level, pattern oriented abstraction API)
• (TAO = open source ORB)

In addition to presenting some of the PACE code, I intend to discuss some of the pitfalls of porting middleware and how we overcame them in our current work on PACE as well as how they should be addressed as PACE continues to grow.

Additional information regarding ACE and PACE and TAO is available as well as a full source distribution of TAO + ACE + PACE.

If you have any questions, suggestions or contributions regarding PACE, please write to us or subscribe to the pace-users mailing list (send email to majordomo@cs.wustl.edu with "subscribe pace-users" in the body, not the subject line ;-)