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Currie Colket <[log in to unmask]>
Reply To:
Currie Colket <[log in to unmask]>
Thu, 7 Mar 2002 18:02:02 -0500
text/plain (183 lines)
Dear Team-Ada:

For those traveling to the DC Area next week:


     To Members and Friends of DC SIGAda

Next Meeting:

     Thursday, 14 March 2002, 7:30 P.M. (Refreshments and Social
     at 7:00 P.M.) at the new MITRE2 Building in McLean, Virginia.
     DC SIGAda and Baltimore SIGAda will feature a presentation
     titled: Ada 95 Protected Objects for Synchronizing Shared
     Data Structures


     Ada 95 Protected Objects for Synchronizing Shared Data

     Software systems frequently have the need to share critical data
     where two or more tasks must synchronize their manipulations of
     shared data structures. The need is readily apparent when one
     considers one task updating the latitude and longitude of a track
     while other tasks access this latitude and longitude. If the task
     updating the coordinates gets suspended after the latitude is
     updated and before the longitude gets updated, it is possible for a

     second task to access the updated latitude and an older longitude.
     This is clearly not useful for an application attempting to
     accurately target the track. There are requirements to effectively
     synchronize data in many domains ranging from avionics to
     financial. There are many applications where this inconsistent
     data would violate data integrity and safety constraints.

     In Ada 83, the rendezvous was used for both inter-task
     communication and for synchronizing access to shared data
     structures. This was safe, but the rendezvous resulted in a
     relatively high overhead to share data structures safely. One of
     the nice new features of Ada 95 was the addition of Protected
     Objects. A Protected Object provides a safe data-oriented
     synchronization mechanism that is highly efficient.

     This presentation will start at the basics discussing protected
     types, protected objects, and protected operations. It will discuss

     the Ada Language Reference Manual syntax with a number of
     useful examples. Quality and Style is also important.
     Recommended styles and usage from the Ada Quality and Style
     Guide will be addressed. Issues resulting from actual use on real
     systems will be presented. It is possible to obtain information on
     the use of protected objects from analysis tools. Thoughts on this
     type of analysis will be included and opportunities to brainstorm
     alternative uses will be presented.


     Mr. Currie Colket is the Chair of ACM SIGAda for Meetings and
     Conferences, the Chair of the SIGAda Ada Semantic Working
     Group, and Chair of the ISO WG9 ASIS Rapporteur Group. He
     recently retired from the DoD where he served in the Air Force
     as an Airborne Surveillance Officer on AWACS and a computer
     scientist for the United States Navy. Mr. Colket is currently a
     software systems engineer for MITRE. His current tasks involve
     software engineering support for a variety of programs. Prior to
     his affiliation with MITRE, he was a consultant for the Software
     Program Manager's Network (SPMN). He has a Bachelor of
     Science from Case Institute of Technology, a Master of Business
     Administration from the University of Southern Mississippi and a
     Master of Science in Computer Science from the Ohio State
     University. His coordinates are:

          Currie Colket
          The MITRE Corporation
          7515 Colshire Drive
          McLean, Virginia 22102-7508

          Phone: +1 (703) 883-7381
          FAX: +1 (703) 883-1339
          Email: [log in to unmask]


     Room 1N100 A/B
     The MITRE Corporation
     7515 Colshire Drive
     McLean, Virginia 22102-7508


     MITRE2 is on Colshire Drive just inside the beltway off of Route

     Those coming from the Dulles Access Toll Road or I-495
     north of the Dulles Access Toll Road will want to access
     Colshire Drive by:
          1. Take the Dulles Airport Access and Toll Road to Exit 19;
             (From I-495, this is labeled "To East I-66");
          2. Take Exit 19A;
             (following signs to Route 123 South, Tysons Corner);
          3. Bear right onto Route 123 (towards Tysons Corner)
          4. Turn left onto Colshire Drive (at first light);

     Those coming from I-495 south of Route 123 (Dolley Madison
     Boulevard) will want to access Colshire Drive by:
          1. Take Exit 46B (McLean, Route 123);
          2. Go North onto Route 123;
          3. Turn right onto Colshire Drive (at second light);

     From Colshire Road and Route 123:
          A. Take third right OFF OF THE TRAFFIC CIRCLE;
             (a logical left hand turn);
          B. Proceed ~ 50 meters; Turn right into parking garage.
          C. Visitor Parking is located on Levels 2 and 3
             (the walkway to the lobby is on Parking Level 2)
          D. If door is locked, contact Security using phone by door
             (at entrance to MITRE2 from the Parking Garage)
          E. Check in with Security at Security desk in lobby
             (You will need a photo ID)

     To obtain a map of MITRE2 Building and the MITRE Campus,
     visit =>

Please Put on Your Calendar

      o  Tuesday, 9 April 2002 for a joint SIGAda Chapter Meeting
          hosted by the Baltimore SIGAda Chapter at JHU/APL.
          Frank Beard will be speaking on the ObjectAda GUI
          Builder. This is a rescheduling of his 11 September 2001

     o   Thursday, 9 May 2002 for our last SIGAda Chapter
          Meeting until Fall, hosted by the DC SIGAda Chapter in
          Rockville, Maryland. Speaker is TBD.

DC SIGAda Home Page and Maillist

     Please visit the DC SIGAda Web site at for additional information.

     Please provide suggestions on the Web site and its contents. We
     are particularly interested in ways the DC SIGAda Home Page
     can serve you better.

     Consider subscribing to our e-mail list. Simply send an email to:

          [log in to unmask]

     with the body containing:

          subscribe SIGAda-DC Your Name

     To be removed from the list, send an email request to:

          [log in to unmask]

     with the body containing:

          signoff SIGAda-DC


     We will have light foods and refreshment at 7:00. The meeting
     begins at 7:30 pm.

     Many thanks to all earlier participants, contributors, speakers,
     advisors, and friends, who are involved in helping to produce and
     attend the meetings.

     Please forward this message to people who might be interested in
     attending. We welcome all new members as our attendance and
     interests grow.

     Consider registering for inclusion on our e-mail list.
     Registration instructions are provided on the DC SIGAda Web

Jeff Castellow, Chair, DC SIGAda