• TR00-276 (PDF)

Real-Time CORBA
V.F. Wolfe, L.C. DiPippo, G. Cooper, R. Johnston, P. Kortman, B. Thuraisingham
Oct. 2000
This paper presents a survey of results in developing Real-Time CORBA, a standard for real-time management of distributed objects. The paper includes background on two areas that have been combined to realize Real-Time CORBA: the CORBA standards that have been produced by the international Object Management Group; and techniques for distributed real-time computing that have been produced in the research community. The survey describes major RT CORBA research efforts, commercial development efforts, and standardization efforts by the Object Management Group.  A version of this paper appeared in IEEE Transactions on Parallel and Distributed Systems, v. 11, no. 10, Oct. 2000.
 
• TR99-269 (PDF)

Schedulability Analysis in Static Real-Time Systems: Priority Mapping and DASPCP for Real-Time CORBA
Ramachandra Bethmangalkar
May 1999
This thesis describes modifications to the PERTS real-time analysis software to integrate the Distributed Affected Set Priority Ceiling Protocol (DASPCP) and a priority mapping algorithm that maps global priorities to available local priorities on the nodes of a distributed system.

• TR98-261 (PDF)

Scheduling and Priority Mapping for Static Real-Time Middleware
L. DiPippo, V. F. Wolfe, L. Esibov, G. Cooper, R. Johnston, B. Thuraisingham, J. Mauer
Sept. 1998
This paper presents a middleware real-time scheduling technique for static, distributed, real-time applications. The technique uses global deadline monotonic priority assignment to clients and the Distributed Priority Ceiling protocol to provide concurrency control and priorities for server execution. The paper presents a new algorithm for mapping the potentially large number of unique global priorities required by this scheduling technique to the restricted set of priorities provided by commercial real-time operating systems.  A version of the paper  appeared in Real-Time Systems Journal, 20, 155-182, 2001.

• TR98-263 (PDF)

A Scheduling Service for a Dynamic Real-Time CORBA System
L. DiPippo, V. F. Wolfe, R. Ginis, M. Squadrito, T. Wheeler
Aug. 1998
This paper describes the design and implementation of a real-time scheduling service for a Dynamic Real-Time CORBA system.  A version of this paper appeared in the Proceedings of The Twenty-Second Annual International Computer Software and Application Conference

• TR98-260  (PDF)

Expressing and Enforcing Timing Constraints in a Dynamic Real-time CORBA System
Victor Fay Wolfe, Lisa Cingiser DiPippo, Roman Ginis, Michael Squadrito, Steven Wohlever, Igor Zykh and Russell Johnston
June. 1998.
This paper describes our Dynamic Real-Time CORBA system which meets the requirements of the OMG real-time SIG for expression and enforcement of end-to-end timing constraints. The paper also describes performance tests that demonstrate the ability of the system to enforce expressed timing constraints.

• TR99-270 (PDF)

Support for Automated Schedulability Analysis for Distributed Real-Time Middleware
Levon Esibov
May 1998
This thesis provides contributions in real-time scheduling theory and tools for distributed systems.  In particular it addresses techniques to perform schedulability analysis of Real-Time CORBA systems.
 
• TR98-266 (PDF)

Integration of Real-Time CORBA into an Existing Distributed Planning Architecture
Yuruo Chen
May 1998
This thesis describes the integration of a dynamic real-time CORBA system into the JFlex planning application.
 
• TR98-265 (PDF)

Integration of Real-Time Object-Oriented Database and Real-Time CORBA into Legacy Software
Qingli Jiang
May 1998
This thesis describes the integration of a main-memory real-time object-oriented database into the JFlex planning application.
 
• TR98-262 (PDF)

Concurrency Control in Real-Time Object-Oriented Systems:  The Affected Set Priority Ceiling Protocols
M. Squadrito, L. Esibov, L. DiPippo, V. F. Wolfe, G. Cooper, B. Thuraisingham, P. Krupp, M. Milligan, R. Johnston
Apr. 1998
This paper presents the Affected Set Priority Ceiling Protocols (ASPCP) for concurrency control in real-time object-oriented systems.  These protocols are based on a combination of semantic locking and priority ceiling techniques. This paper shows that the ASPCP protocols provide higher potential concurrency for object-oriented systems than existing Priority Ceiling protocols, while still bounding priority inversion and preventing deadlock.  A version of this paper appeared in the Proceedings of the The 1st IEEE International Symposium on Object-oriented Real-time distributed Computing.
 
• TR99-272 (PDF)

Real-Time CORBA Development at MITRE, NRaD, TriPacific, and URI
G. Cooper, L. DiPippo, L. Esibov, R. Ginis, R. Johnston, P. Kortman, P, Krupp, J. Mauer, M. Squadrito, B. Thuraisingham, S. Wohlever, V. F. Wolfe
Dec. 1997
This paper describes Real-Time CORBA results and work in progress stemming from a collaborative effort involving researchers at MITRE, NRaD, Tri-Pacific Software, and the University of Rhode Island.  A version of this paper appeared in the Proceedings of the IEEE Workshop on Real-Time Middleware, Dec. 1997.
 
• TR97-256 (PDF)

Real-Time CORBA
Victor Fay Wolfe, Lisa Cingiser DiPippo, Roman Ginis, Michael Squadrito, Steven Wohlever, Igor Zykh and Russell Johnston
June. 1997.
This paper describes the requirements for real-time extensions to the CORBA standard which are being developed by the OMG's real-time SIG on Real-Time CORBA. The paper surveys efforts that are developing Real-Time CORBA systems, emphasizing work done at NRaD and URI.  A version of this paper appeared in the Proceedings of the Real-Time Technology and Applications Symposium, June 1997.
 
• TR97-254 (PDF)

Timed Distributed Method Invocations in CORBA
Igor Zykh
May 1997.
This thesis presents the syntax, semantics and support for some necessary features in a real-time distributed computing environments for expression and enforcement of end-to-end timing constraints. The paper describes Timed Distributed Method Invocations (TDMIs), Global Time Service, and Real-Time Event Service.
 
• TR97-253  (PDF)

Concurrency Control in a Dynamic Real-Time Distributed Object Computing Environment
Steven C. Wohlever
May 1997.
This paper describes an implementation of a concurrency control mechanism for real-time CORBA resources. The mechanism uses priority inheritance to bound priority inversion.
 
• thesis (PDF)

Real-Time COTS Message Communication for C3I Systems
Robert J. Pollack, Jr.
May 1997.
This thesis investigates the viability of utilizating a commercial-off-the-shelf (COTS) based distributed system to meet the real-time data requirements of the Combat Command Control and Intelligent (C3I) systems fo the New Strategic Submarine Nuclear (NSSN) submarine.
 
• Response to OMG RFI (html)

Real-Time CORBA in the Distributed Hybrid Database Architecture
Victor Fay Wolfe and Russell Johnston
Feb. 1997.
This is a 10 page summary of our work on Real-Time CORBA that we have submitted to the Object Management Group. It summarizes and links to our more detailed papers.
 
• TR96-251(PDF)

The Design of an Open System with Distributed Real-Time Requirements
R. Ginis, J.J. Prichard, and V. Fay Wolfe
June 1996
This paper describes the real-time requirements of the C3I system of the US Navy's New Attack Submarine. It presents a CORBA wrapper for a COTS real-time database. A version appeared in the Proceedings of the IEEE Real-Time Technology and Applications Symposium, June, 1996.
 
• NRaD Tech Report (html)

Real-Time CORBA
Russell Johnston, V.F. Wolfe, M. Steele
June 1996
This is a draft of an NRaD techreport. It contains a section on requirements for real-time CORBA which formed the original Section 1.2 and 4 of the whitepaper from the OMG Real-Time Special Interest Group (authored by V.F. Wolfe in July 1996).
 
• TR95-244 (PDF)

Real-Time Method Inovcations in Distributed Environments
V. Fay. Wolfe, J. Black, B. Thuraisingham, P. Krupp
Jan 1996
This paper describes the essential element to real-time CORBA extensions: how to do timed method invocations in a CORBA environment. A similar version appeared in the Proceedings of the Interational High Performance Computing Conference, December, 1995.
 
• Position Paper (ascii text)

Real-Time Extensions to The Common Object Request Broker Architecture
B. Thuraisingham, P. Krupp, A. Schaffer, V. Fay Wolfe
Jan. 1995
This is a short, initial position paper on real-time extensions to CORBA. A similar version appeared in the Proceedings of the OOPSLA Workshop on CORBA, October 1994.

Real-Time Object Oriented Databases

• TR02-284 (PDF)

A Replication Strategy for Distributed Real-Time Object-Oriented Databases
P. Peddi and L. DiPippo
April 2002
This paper describes a replication algorithm for distributed real-time object-oriented databases in a static environment. All data requirements are specified a priori, and the algorithm creates replication transactions that copy remote data to a local site in order to guarantee that every data request reads temporally valid data. The algorithm conditions are proven to be necessary and sufficient for providing this guarantee. Test results indicate that under most conditions, this replication strategy is better than total replication, which is a typical strategy used in distributed databases. A version of this paper will appear in the Proceedings of The 5th IEEE International Symposium on Object-oriented Real-time distributed Computing, Washington, D.C., April 2002.
 
• TR01-282 (PDF)

A Replication Strategy for Distributed Real-Time Object-Oriented Databases
Praveen Peddi
May 2001
This thesis describes an algorithm called the Just- In-Time Real Time Replication (JITRTR) Algorithm. The JITRTR algorithm generates replication transactions that copy required data in a distributed real-time object-oriented database where and when it is needed.  The algorithm guarantees that all requests for data will read temporally valid local copies of the data.
 
• TR98-264 (PDF)

The Affected Set Priority Ceiling Protocols for Real-Time Object-Oriented Systems
M. Squadrito, L. Esibov, L. DiPippo, V. F. Wolfe, G. Cooper, B. Thuraisingham, P. Krupp, M. Milligan, R. Johnston, R. Bethmangalkar.
July. 1999
This paper presents two concurrency control protocols for real-time object-oriented systems.  One of the protocols is designed for single-node systems and the other is for distributed systems.  Both protocols combine the features of semantic concurrency control for added concurrency, with priority ceiling techniques for deadlock prevention and bounded priority inversion.  A version of this paper appeared in the International Journal of Computer Systems Science and Engineering - Special Issue on Object-Oriented Real-Time Distributed Systems, v. 14. no.4.
 
• TR98-267 (PDF)

Scheduling with Temporal and Logical Constraints
Gregory Jones
May 1998
This dissertation presents a unified approach to scheduling and concurrency control that considers both temporal constraints and logical constraints.  It describes a bi-criteria approach that uses a frontier of possible solutions to express the relative merits of schedules that perform well in each of the performance measures.
 
• Book Chapter (PDF)

The RTSORAC Real-Time Object-Oriented Database Prototype
V. F. Wolfe, J. J. Prichard, L. DiPippo, J. Black
Dec. 1997
This book chapter describes the design and implementation of the RTSORAC real-time object-oriented database model and prototype.  It appears as a chapter in the book Real-Time Database Systems:  Issues and Applications, Kluwer Academic Press, 1997.
 
• Book Chapter (PDF)

Towards Unifying Database Scheduling and Concurrency Control:  A Frontier Approach
G. Jones, L. DiPippo, V. F. Wolfe
Sept. 1997
This paper describes a scheduling model for unified database scheduling and concurrency control that supports a bi-criteria scheduling approach.  Techniques based on this model handle logical consistency, temporal consistency, and the trade-off between them.  A version of this paper appeared in Real-Time Databases and Information Systems:  Research Advances, Kluwer Academic Press, Sept. 1997.

• TR96-247 (PDF)

Object-Based Semantic Real-Time Concurrency Control with Bounded Imprecision
L. Cingiser DiPippo, V. Fay Wolfe
Feb. 1997
This paper describes how semantic object-based concurrency control can bound logical imprecision in the database. It contains a set of sufficient conditions for achieving epsilon serializabilty and proof that they are sufficient. A version has appeared in IEEE Transactions on Knowledge and Data Engineering vol. 9 no. 1.

• TR97-257(PDF)

SMOS: A Memory-Resident Object Store
Yong Yuan
Jan 1997
This paper describes an implementation of Open OODB replacing Exodus disk-resident memory with shared memory.
 
• TR95-245 (PDF)

Performance of Object-Based Semantic Real-Time Concurrency Control
L. Cingiser DiPippo and V. Fay Wolfe
Oct 1996
This paper presents performance results for object-based semantic real-time concurrency control. The protocol is compared with other object locking techniques which use varying degrees of semantic knowledge. Overall, the semantic locking technique misses fewer deadlines and reads less temporally inconsistent data than the other techniques.
 
• TR97-258 (PDF)

Extending the Priority Ceiling Protocol Using Read/Write Affected Set Semantics
Michael Squadrito
April 1996
This thesis presents the Affected Set Priority Ceiling Protocol (ASPCP) for concurrency control in real-time object-oriented systems. The ASPCP uses the semantic information of objects in a real-time system to provide a higher potential for concurrency than existing Priority Ceiling protocols.  It also presents proofs that the protocol still prevents deadlock and bounds priority inversion.   Finally, this thesis describes a prototype implementation on which tests were conducted, and analyzes the results.
 
• TR96-250 (PDF)

The Affected Set Priority Ceiling Protocol For Real-time Object-Oriented Databases
M. Squadrito, L. Cingiser DiPippo, and V. Fay Wolfe
Mar 1996
This paper describes adding priority ceilings to our earlier work on semantic concurrency control. This extension elminates deadlock, bounds priority inversion, and is simpler to implement than our original semantic concurrency control technique.  A version of this paper appears in the Proceedings of the First International Workshop on Real-Time Databases, March 1996.
 
• TR96-249 (PDF)

Real-Time Databases
L. Cingiser DiPippo and V. Fay Wolfe
May 1995
This long paper surveys real-time database research and technology.  This paper appears as a chapter in Database Systems Handbook, Multiscience Press, 1997.
 
• Dissertation (PDF)

Semantic Real-Time Object-based Concurrency Control
L. Cingiser DiPippo
May 1995
This dissertation presents and analyzes (including simulations) semantic real-time object-based concurrency control.
 
• TR94-236 (PDF)

The Design of Real-Time Extensions to the Open Object-Oriented Database System
V. Fay Wolfe, L. Cingiser DiPippo, J. J. Prichard, J. M. Peckham, P. Fortier
June 1994
This is a shorter version of our initial implementation of a real-time object-oriented database in Texas Instruments Open Object-Oriented Database system. A version of this paper appeared in the Proceedings of the Workshop on Object-Oriented Real-Time Dependable Systems, October, 1994.
 
• TR94-231 (PDF)

RTSORAC: Design of a Real-Time Object-Oriented Database System
J. Peckham, V. Fay Wolfe, J. J. Prichard, L. Cingiser DiPippo
Feb. 1994
This is a detailed description of our first implementation of the a real-time object-oriented database using the RTSORAC model and semantic concurrency control.
 
• TR93-219 (PDF)

Real-Time Semantic Object-based Concurrency Control
L. Cingiser DiPippo and V. Fay. Wolfe
Dec. 1993
This paper describes real-time semantic object-based concurrency control. A version appeared in The Proceedings of IEEE Real-Time Systems Symposium. Dec. 1993.
 
• TR93-216 (PDF)

A Model for Real-Time Object-Oriented Databases
V.Fay Wolfe,L. Cingiser, J. Peckham, J. Prichard
Jan. 1993
This paper describes the basic RTSORAC real-time object-oriented model used in all of our work. A version appeared in the Conference on Database and Expert Systems Applicaitons, Greece, Sept. 1994.

Distributed Real-Time Collaborative Systems

• TR99-274  (PDF)

A UML Package for Specifying Real-Time Objects
L. DiPippo and L. Ma
Nov. 1999
The Unified Modeling language provides a robust set of tools for modeling software systems.  However, these tools do not directly address the requirements of real-time systems.  Many real-time systems require the specification of data that has strict timing constraints.  This paper presents a UML package for specifying real-time objects called RT-Object.  The constructs in the package are based on the objects of the RTSORAC (Real-Time Semantic Objects Relationships And Constraints) model.  The RT-Object package has been used to design real-time objects in a Real-Time Multi-User Virtual Environment in which widely distributed users collaborate in time-critical planning and decision making.  A version of this paper appears in Computer Standards and Interfaces 22 (2000) 307-321.
 
• TR99-268 (PDF)

Integration of Real-Time Objects into a Distributed Multi-User Virtual Environment
Ling Ma
May 1999
This thesis describes the design and implementation of real-time objects in the C2MUVE multiuser virtual environment.  The design involves integrating real-time features into UML data objects.  The implementation places these objects into a Java-based CORBA environment.
 
• ONR Report (PDF)

Real-Time Collaborative Planning and Multi-User Environment
L. DiPippo and R. Johnston
Dec. 1998
This report specifies the design objectives of the Distributed Real-Time Collaborative Systems (DRTCS) effort at URI and SPAWAR.  It includes the integration of real-time objects, real-time CORBA, real-time object-oriented databases, real-time scheduling, and real-time agents into a collaborative environment such as C2MUVE.

Real-Time Multi-Agent System Services

• TR01-281(PDF)

Expressing Quality of Service in Agent Communication
L. C. DiPippo and L. Nair
June 2001
This paper presents extensions to a well-known agent communication language for the expression of quality of service.  It describes the semantics of the extensions, while allowing quality of service to be interpreted as broadly as possible.  The paper then describes the specific extensions to KQML through added performative parameters.  A prototype implementation of the extended language is also discussed.  A version of this paper appears in the Proceedings of the 2001 International Conference on Aritficial Intelligence, Las Vegas, Nevada, June 2001.
 
• TR00-279(PDF)

Extending ACL to Support Communication in a Real-Time Multi-Agent System
Lekshmi S. Nair
Dec. 2000
This thesis describes extensions to an agent communication language to support real-time communication. It describes the implemention of the extended ACL in KCOBALT, an agent communication tool-kit based on KQML and CORBA. The extensions we have made to KQML are equally applicable to FIPA ACL .
 
• TR00-280 (PDF)

A Real-Time Multi-Agent System Architecture for E-Commerce Applications
L. C. DiPippo, V. F. Wolfe, L. Nair, E. Hodys, O. Uvarov
Dec. 2000
This paper describes an architecture for real-time multi-agent systems (RTMAS) that builds upon an existing real-time CORBA architecture.  The RTMAS architecture provides real-time agent services for real-time agent communication, real-time agent scheduling and real-time agent facilitation.  These services work together to allow for the expression and enforcement of real-time agent interactions.  The paper describes the design of these services, along with a prototype implementation of the RTMAS architecture that is based upon an existing agent communication implementation.  A shorter version of this paper will appear in the Proceedings of the The Fifth International Symposium on Autonomous Decentralized Systems, March 2001.
 
• TR00-275 (PDF)

A Scheduling Algorithm for a Real-Time Multi-Agent System
Ethan Hodys
Aug. 2000
This thesis describes the design of a model and scheduling algorithm for real-time multi-agent systems.  The scheduling model is based upon the assumption that real-time agents provide multiple execution strategies for solving a given problem, with varying execution times and quality of results.  The algorithm schedules by EDF unless an overload condition occurs.  In this case, a load reduction heuristic is employed to reduce the execution time, and therefore expected quality, of currently scheduled agent tasks.
 
• TR99-273 (PDF)

Towards a Real-Time Agent Architecture - A Whitepaper
L. DiPippo, B. Thuraisingham, E. Hodys
Nov. 1999
Applications such as military training simulations, and electronic commerce can benefit from the flexible and responsive nature of multi-agent systems.  These applications have inherent timing constraints on the operations and interactions that the agents might perform.  This paper presents a real-time agent architecture in which agents communicate, cooperate, coordinate and negotiate to meet the goals of a particular application under specified timing constraints.  The architecture provides a real-time CORBA layer to handle underlying real-time communication.  It also has a real-time agent communication layer in which agents interact via a real-time extension of a well-known agent communication language.  A version of this paper will appear in the Proceedings of the Fifth International Workshop on Object-oriented Real-time Dependable Systems.

Real-Time Object-Oriented Applications

• TR96-251 (postscript)

The Design of an Open System with Distributed Real-Time Requirements
R. Ginis, J.J. Prichard, and V. Fay Wolfe
June 1996
This paper describes the real-time requirements of the C3I system of the US Navy's New Attack Submarine. It presents a CORBA wrapper for a COTS real-time database. A version appeared in the Proceedings of the IEEE Real-Time Technology and Applications Symposium, June, 1996.
 
• TR93-214 (postscript)

Real-Time Object-Oriented Database Support for Intelligent Program Stock Trading
V. Fay Wolfe, K.F. Lau
Jan. 1993
This paper applies our RTSORAC model to porgrammed stock trading with real-time constraints. Timed atomic commitment is also employed. A version of this paper appeared in The Journal of Database Management, Fall, 1995.
 
• TR93-215

Real-Time Considerations in Submarine Target Motion Analysis (No electronic version. Must be ordered from URI Dept. of Computer Science Secretary)
G.A. Bussiere, J. Oblinger, V. Fay Wolfe
Jan. 1993
This paper describes the real-time aspects of the MATE submarine tracking application. A version appeared in the Proceedings of the IEEE Workshop on Real-Time Applications, May, 1994.

Real-Time SQL

• Dissertation (PDF)

RTSQL
J.J. Prichard
July 1995
This dissertation presents and analyzes (including a prototype implementation) real-time extensions to SQL.
 
• TR94-241 (postscript)

Real-Time SQL: Extensions for Support of Real-Time Database Systems
J. J. Prichard, P. J. Fortier, Victor Fay Wolfe
Oct. 1994
This is a RTSQL "whitepaper" that was presented to ANSI for the working draft of real-time extensions to SQL.
 
• TR94-235 (postscript)

Flexible Real-Time SQL Transactions
P. Fortier, J. J. Prichard, V. Fay Wolfe
May 1994
This is a short paper describing flexible real-time transaction design as specified in real-time SQL. A version of this paper appeared in the Proceedings of the IEEE Real-Time System Symposium, December, 1994.

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