The High Level Architecture ( HLA ) is a standard for distributed simulation, used when building a simulation for a larger purpose by combining (federating) several simulations. The standard was developed in the 1990s under the leadership of the US Department of Defense and was later transitioned to become an open international IEEE standard. It is a recommended standard within NATO through STANAG 4603. Today the HLA is used in a number of domains including defense and security and civilian applications.
30-438: The purpose of HLA is to enable interoperability and reuse. Key properties of HLA are: HLA forms the basis for developing standardized and extendable FOMs in different communities, for example in aerospace and defense. The architecture specifies the following components. Together the above components form a Federation . The HLA standard consists of three parts: HLA was initiated in the early 1990s when Dr. Anita K. Jones ,
60-947: A ballerina and danced in several Hollywood films, taught her daughter a love of painting. Born in Fort Worth, Texas and raised in Houston , Anita graduated as valedictorian of her high school class in 1960. Jones received an A.B. from Rice University in Mathematics in 1964, a Master of Arts in English Literature from the University of Texas at Austin , in 1968, and a Ph.D. in computer science from Carnegie Mellon University in 1973. While at Carnegie Mellon, she met her future husband, William A. Wulf . Jones remained at Carnegie Mellon as an assistant professor, with promotion to associate professor in 1978. With William A. Wulf , her husband, Jones
90-413: A federate Divesting the attribute and another federate Acquiring the attribute. There are two main patterns: “pull” that are initiated by the acquiring federate and “push” that are initiated by the divesting federate. Key services for initiating “pull” ownership are: Key services for initiating “push” ownership are: All object instances have a predefined attribute called HLAPrivilegeToDeleteObject. Only
120-403: A federate has finished producing data for the granted time plus the lookahead, it may request to be advanced to a later time, which also means that it promises not to produce any more messages with a time stamp less than the requested time plus the lookahead. The federate is now in the advancing state. Time Regulating : A federate that sends time stamped events is considered Time Regulating since
150-559: A federate using callbacks, which are delivered using calls to an instance of the Federate Ambassador class. In the Web Services API, defined using WSDL , calls are made, and callbacks are fetched, by the federate using Web Services requests and responses. The service group descriptions below focus on key services. Exceptions and advisories are not included. The purpose of Federation Management services, described in chapter 4 of
180-484: A federate with a fixed time step, this is usually the length of the time step. Granted : A federate is granted (allowed to advance) to a particular logical time by the RTI, when all time-stamped messages up to that time have been delivered. The federate can then safely start calculating messages with a timestamp in the future. This timestamp may not be earlier than the granted time plus the federates lookahead. Advancing : When
210-417: A fixed object model, and Aggregate Level Simulation Protocol (ALSP) focusing on simulation of aggregate with time management, ownership management and flexible object models, called confederation models. The purpose of HLA was to provide one unified standard that would meet the simulation interoperability requirements of all US DoD components. The development of HLA was based on four prototypical federations:
240-839: A member of the MIT Corporation. From 1988 to 1992, she was a trustee of the MITRE Corporation . She is a member of the National Academy of Engineering , the Council on Foreign Relations , the National Science Foundation 's National Science Board , and the American Philosophical Society . She has been a member of the Computing Community Consortium "since its inception." Jones received
270-556: A modeling and simulation masterplan, including the High Level Architecture . In 2010, she officially retired but remains involved in the university and continues to mentor young women in technical fields. She is on the Board of Trustees for In-Q-Tel which "is the not-for-profit strategic investor that accelerates the development and delivery of cutting-edge technologies to national security agencies." Since 2004, Jones has been
300-468: A scenario, before the execution can continue. Key services are: Yet another set of service relates to saving and restoring a federation execution. A save operation requires both the RTI and each federate to perform a save of their internal state. A restore operation requires both the RTI and each federate to perform a restore of their internal state. Key services are: Save: Restore: The purpose of Declaration Management services, described in chapter 5 of
330-628: Is commonly known as HLA Evolved. It consists of: Major improvements in IEEE 1516-2010 include Modular FOMs, incorporation of the DLC APIs in C++ and Java, a Web Services API and Fault Tolerance. Machine-readable parts of this version of HLA, such as XML Schemas, C++, Java and WSDL APIs as well as FOM/SOM samples can be downloaded from the IEEE 1516 download area of the IEEE web site . The full standards texts are available at no cost to SISO members or can be purchased from
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#1732855296825360-411: Is used for Time Management timestamps and operations. The logical time axis can be mapped to the scenario time of the federation. An example of such a mapping is to let zero represent the scenario time 8:00 of the 1-Jan-1066 and let an increment by one represent one second of the scenario. Lookahead : A time interval specifying the lowest time in the future for which a federate will produce messages. For
390-851: The Augusta Ada Lovelace Award from the Association of Women in Computing in 2004. She is also the recipient of the Computing Research Association 's Service Award, the Air Force Meritorious Civilian Service Award, and the Department of Defense Award for Distinguished Public Service. The U.S. Navy has named a seamount in the North Pacific Ocean (51° 25’ N and 159° 10’ W) for her. In 2007, she
420-782: The Director of Defense Research and Engineering within the US Department of Defense, gave the Defense Modeling and Simulation Office (DMSO) the task of “assuring interoperability and reusability of defense models and simulations”. In 1995 DMSO formulated a vision for modeling and simulation and established a modeling and simulation masterplan, which included the High Level Architecture. Two protocols for M&S interoperability already existed: Distributed Interactive Simulation (DIS), focusing on real-time platform level simulation with
450-679: The HLA Interface Specification, is to dynamically manage what federate that simulates what aspect of an object instance. In HLA, only one federate is allowed to update a given attribute of a given object instance. That federate is considered the owner of the attribute. A federate that registers a new object instance will automatically be the owner of all attributes it publishes. In some cases, attributes of an object instance may become unowned, i.e. not owned by any federate. Ownership management provides services for transferring ownership of one or several attributes at runtime, which can include
480-447: The HLA Interface Specification, is to enable federates to declare what information they wish to publish (send) and subscribe to (receive) based on object and interaction classes in the FOM. The RTI uses this information to route updates and interactions to subscribing federates. For an object class, publishing and subscribing are performed for a specific set of attributes. For interaction classes,
510-585: The HLA Interface Specification, is to guarantee causality and a correct and consistent exchange of time stamped messages (updates and interactions) in Time Stamp Order (TSO), no matter if the federation executes in real-time, faster-than-real-time, slower-than-real-time or as-fast-as-possible. Some important concepts in HLA Time Management are: Logical time : A time axis in HLA, starting at zero. Logical time
540-496: The HLA Interface Specification, is to manage Federation Executions as well as federation-wide operations such as Synchronization Points and Save/Restore. One set of Federation Management services manages the connection to the RTI, the federation execution and the set of joined federates. Key services are: Another set of services relates to synchronization points. These are federation-wide events where all, or selected federates are required to complete an operation, such as initializing
570-527: The IEEE shop . The development of a new version of HLA started in January 2016 by SISO and is currently ongoing. The HLA standard consists of three parts: The RTI services are defined in the HLA Interface Specification. They are grouped into seven service groups. In addition to these services, the Management Object Model (MOM) provides services that makes it possible to inspect and adjust the state of
600-706: The Platform Prototype Federation, the Joint Training Protofederation, the Analysis Protofederation and the Engineering Prototype Federation. The HLA specification was prototyped and refined, until HLA 1.3 was finally released. To facilitate usage outside of the defense community, HLA was then transitioned into an IEEE standard, maintained by Simulation Interoperability Standards Organization (SISO). To facilitate
630-537: The University of Virginia in 1997. In the field of computer software systems and cyber-security, Dr. Jones has published more than 40 technical articles and two books. Among other things, she gave the Defense Modeling and Simulation Office (DMSO) the task of “assuring interoperability and reusability of defense models and simulations" which led to DMSO formulating a vision for modeling and simulation and establishing
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#1732855296825660-821: The entire interaction, including all parameters, is published and subscribed. Key services are: The purpose of Object Management services, described in chapter 6 of the HLA Interface Specification, is to enable federates to share information about object instances and to exchange interactions. Object instance names can be reserved or be automatically generated. Federates can register object instances of specified object classes, that are then discovered by subscribing federates. Attributes of these object instances can be updated. These updates will be reflected to subscribing federates. Interactions can be sent. These interactions will be delivered to subscribing federates. Key services are: Objects: Attributes: Interactions: The purpose of Ownership Management services, described in chapter 7 of
690-467: The federation programmatically. Most RTIs consist of a Central RTI Component (CRC), which is an executable and Local RTI Components (LRCs), which are libraries that are used by the federates. Services are provided through a C++ or Java API and also using Web services. In the C++ and Java APIs, services are invoked using calls to an instance of the RTI Ambassador class. The RTI delivers information to
720-692: The migration for DIS users, a Federation Object Model corresponding to the fixed object model of DIS was also developed as the Real-time Platform Reference FOM ( RPR FOM ). The following HLA versions exist: HLA 1.3 was published in March 1998 by DMSO. It consists of: The US DoD also published interpretations for HLA 1.3: HLA IEEE 1516-2000 was published in 2000 by IEEE. It consists of: Major improvements in IEEE 1516-2000 included an XML-based FOM with detailed data type specifications, as well as an improved DDM design. The IEEE 1516-2000 standard
750-415: The owner of this attribute for an object instance is allowed to delete the object instance. Ownership of this attribute can be transferred at runtime using the above operations. The information exchange in an HLA federation takes place in real-time with immediate (Receive Order, RO) delivery of messages, unless HLA Time Management has been enabled. The purpose of HLA Time Management, described in chapter 8 of
780-541: The science and technology program. Her responsibilities included the Defense Advanced Research Projects Agency and oversight of the Department of Defense laboratories, as well as being the principal advisor to the Secretary of Defense for defense-related scientific and technical matters. At the time, it was the highest technical job ever held by a woman in the Department of Defense. She returned to
810-462: The time advance by other federates may be regulated by this. Time Constrained : A federate that receives time managed events is considered Time Constrained since the reception of time stamped messages, constrains its time advance. Anita K. Jones Anita Katherine Jones (born March 10, 1942) is an American computer scientist and former U.S. government official. She was Director, Defense Research and Engineering from 1993 to 1997. Jones
840-447: Was a founder and vice president of Tartan Laboratories , a compiler technology company, in 1981. The company was later sold to Texas Instruments. She joined the faculty of the University of Virginia in 1989, but took leave in June 1993 to become the Director of Defense Research and Engineering for the U.S. Department of Defense, a position in which she was responsible for the management of
870-483: Was also complemented by a recommended development process as well as a recommended VV&A process: It was soon found that the 1516-2000 standard had APIs that were slightly different for each RTI implementation. SISO produced a standard with alternate, dynamic link compatible (DLC) C++ and Java APIs: The DLC APIs were later merged into the main standard. The IEEE 1516-2010 standard was published in August 2010 by IEEE and
900-501: Was elected a member of the National Academy of Engineering (1994) for contributions to the theory and implementation of software systems and for extensive public service. Jones' father, a petroleum engineer , encouraged her to pursue a career that would make a difference in the world. He taught her to play chess, helped her on geometry problems, and on weekends took her and her younger brother fishing for catfish, red snapper, and trout on Galveston Bay . Jones' mother, who had trained as
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