HLA规则介绍（翻译）

最近整理和翻译了些研究分布式仿真方面的资料，涉及DIS（distributedinteractive simulation，IEEE1278）的DR部分及HLA（high level architecture, IEEE 1516 &&HLA 1.3)的rules、interface specification等官方文档。这里把rule的部分整理和翻译了一下，以备后续研究。

 

联盟规则

R1、              Federations shall have a FOM, documented in accordance with the OMT. 联盟必须有一个符合对象模型模板OMT的联盟对象模型FOM

R2、              All representation of objects in the FOM shall be in the federates, not in the RTI.联盟中所有与仿真相关的对象实例的表示应该在盟员中进行，而不在RTI

R3、              During a federation execution, all exchange of FOM data among federates shall occur via the RTI. 在联盟执行期间，所有在盟员间交换的FOM数据都应该通过RTI进行

R4、              During a federation execution, federates shall interact with the RTI in accordance with the HLA interface specification. 在联盟执行期间，盟员应该按照HLA接口规范与RTI通讯

R5、              During a federation execution, an attribute of an instance of an object shall be owned by only one federate at any given time. 在联盟执行期间，任何时刻同一实例属性最多只能够为一个盟员所拥有

盟员规则

R6、              Federates shall have a SOM, documented in accordance with the OMT. 盟员必须有一个符合对象模型模板OMT的仿真对象模型SOM

R7、              Federates shall be able to update and/or reflect any attributes of objects in their SOM, and send and/or receive SOM interactions externally, as specified in their SOM. 盟员应该能够更新/反射SOM中描述的任何实例属性，发送/接受SOM中描述的交互

R8、              Federates shall be able to transfer and/or accept ownership of attributes dynamically during a federation execution, as specified in their SOM. 在联盟执行期间，盟员必须具有动态接收和转移对象属性所有权的能力

R9、              Federates shall be able to vary the conditions under which they provide updates of attributes of objects, as specified in their SOM. 盟员应能改变其SOM中规定的更新实例属性值的条件

R10、          Federates shall be able to manage local time in a way which will allow them to coordinate data exchange with other members of a federation. 盟员应能管理好局部时钟，以保证与其他盟员进行协调数据交换

 

R1、The FOM shall document theagreement among federates on data to be exchanged at runtime and the conditionsof the data exchange (e.g., updates to be sent when changes exceed a certainvalue). As such, the FOM is an essential element in defining a federation. TheHLA does not prescribe which data are included in the FOM (this is the responsibilityof the federation user and developer). The HLA does require that FOMs shall bedocumented in the format prescribed in IEEE P1516.2, Draft Standard [for]Modeling and Simulation (M&S) High-Level Architecture (HLA) – Object ModelTemplate (OMT)  to support reuse of  a  FOMby new users for their own purposes.

联盟对象模型FOM将运行时盟员间数据交换的协议和条件文档化，它是定义一个联盟的基本要素。HLA不限定FOM中的数据类型，可由联盟用户和开发者决定，但HLA要求将FOM以OMT(IEEE P1516.2标准)格式文档化，以支持新用户重用FOM。

Theformalization of agreements for information exchange is an important element ofthe HLA. The HLA is domain independent and can be used to support federationsfor a wide variety of uses. The FOM shall be the means for specifying the dataexchange for an application of the HLA. By formalizing the development of theseagreements and requiring that the results be documented in a common format, theHLA provides the means for understanding the key elements of a federation andfor assisting in the reuse of the federation, in whole or part. Such reuse is agoal of the HLA. In addition, the FOM provides the basis for some of the dataused to initialize the RTI for the federation.

信息交换协议的规范化是HLA的重要内容。HLA独立于应用领域，能用来支持具有广泛用途的各类联盟。FOM是一种用来规范HLA应用的数据交换方法。通过规范这些协议的开发和要求，结构将以公共格式文档化。HLA提供了理解联盟的关键元素和协助联盟部分或整体重用的方法。另外，FOM还提供了一些用于初始化RTI的数据。

 

R2、One basic idea behind the HLAis to separate simulation-specific functionality from general-purposesupporting infrastructure.  In the HLA,representation of simulated object instances (e.g., ownership of instanceattributes, where “ownership” is defined as having the responsibility to updatevalues) shall take place in the simulations (or, more generally, thefederates); the RTI shall provide functionality similar to a distributedoperating system, which is needed to support interaction of object instancesacross the federation. All simulation-associated  instance attributes shall be owned by thefederates, not by the RTI. The RTI may own instance attributes associated withthe federation management object model(MOM).

将具体的仿真功能与通用的支撑服务分离是HLA的基本思想之一。在HLA中，应该在联盟内对其具体仿真对象的对象实例进行描述而不是在RTI中。RTI提供给盟员的服务类似分布式操作系统提供给应用程序的服务，因此可以说RTI是一个面向仿真的分布式操作系统。RTI提供给盟员的服务主要用以支持联盟内对象实例间的交换。所有与仿真有关的实例属性应该由盟员拥有而不是RTI。RTI可拥有与联盟管理对象模型(federation management object model, MOM)有关的属性。

Simulationfunctionality was separated from federation support services for severalreasons. First, the RTI services are intended to be the basic set of broadlyreusable capabilities needed to support federations across the widest range ofDoD (and other) users. These are essentially coordination and managementservices supporting federation operations, time coordination, datadistribution, etc. Because they apply across a range of HLA applications, theseservices can be provided most cost effectively as services to the applicationsrather than as components of the applications themselves. Separation of the RTIservices has the added advantage of freeing the federates to focus on theirprimary objective of representing object instances to meet the needs of a useror application domain. This approach frees the developers of simulations frominvesting time and resources in these basic common services. The RTI may usedata about instance attributes and interactions to support RTI services (e.g.,declaration management), but these data are merely used by the RTI, notchanged.

RTI服务应该能支持各种联盟，它是能被广泛重用的基本服务集，包括最基本的协调与管理服务，如联盟运行时间协调和数据分发等。由于它们的应用范围非常广泛，因此以标准服务的形式统一提供，比由用户自己定义效率更高。同时，这使得盟员能集中处理应用领域的问题，减少仿真应用开发者投入的时间及资源。所以，在HLA中仿真功能应与联盟支撑服务分离。RTI可以传递对象的属性与交互实例数据来支持盟员间的交互，但RTI不能改变这些数据。

 

R3、The HLA shall specify a setof interfaces to services in the RTI to support coordinated exchange ofinstance attribute values and interactions in accordance with the FOM for thatfederation. Under the HLA, intercommunication among federates in participatingfederations shall be executed by the exchange of data via the RTI services.

         HLA在RTI中指定了一组接口服务来支持各盟员按照联盟FOM的规定对实例属性值和交互实例进行交换，以支持联盟范围内盟员间的通信，在HLA体制下，多个联盟盟员间的通信是借助RTI提供的服务来进行的。

Based on theFOM, federates shall identify to the RTI what information they will provide andrequire, along with instance attribute and interaction data corresponding tothe changing state of object instances in the federate. The RTI shall thenprovide the coordination, synchronization, and data exchange among  the federates to permit a coherent executionof the federation. Ensuring that the right data is provided at the right timesand that the data is used in a substantively correct way shall be theresponsibility of the federates; the RTI shall ensure that the data isdelivered to the using federates in accordance with their declared requirements(which data, reliability of transport, event ordering, etc.) to provide a commonview of shared data across the federations as specified in the FOM. To ensurethat the coordination needs of the distributed applications (federations) aremet in a consistent way across all participants in a federation and over thelife of a federation execution, RTI services shall be used. If a federationwere to exchange data representing state changes of shared object instances orinteractions outside of the RTI service suite, the coherency of the distributedapplication would be violated. The reason for providing common runtime-infrastructureservices to federations is to provide in common the needed basic functionalityto permit coherency in data exchange among the simulations, thereby reducingthe costs of developing and forming new federations.

根据FOM的规定，各盟员将实例属性与交互实例的数据提供给RTI，由RTI来完成盟员间的协调、同步及数据交互等功能。盟员负责在正确的时间内提供正确的数据，而RTI保证将数据按照声明的要求传递给需要数据的盟员，以确保按照FOM的规定在整个联盟范围内形成一个公共的用心数据视图。为保证联盟中所有盟员在整个系统的运行期间保持协调一致，所有盟员都必须通过RTI的服务来交换数据，如果一个联盟在RTI外交互数据，则联盟的一致性将被破坏。公共的RTI服务保证了在盟员间数据交换的一致性，减少开发新联邦的费用。

 

R4、The HLA shall provide astandard specification for accessing RTI services to support interfaces betweenfederates and the RTI (see  IEEE P1516.1,Draft Standard [for] Modeling and Simulation (M&S) High-Level Architecture (HLA)– Federate Interface Specification). Federates shall use these standardinterfaces to interact with the RTI. This interface specification shall definehow simulations interact with the infrastructure. However, since the interfaceand the RTI will be used for a wide variety of applications requiring dataexchange of diverse characteristics, the interface specification says nothingabout the specific federate data to be exchanged over the interface. Dataexchange requirements between federates shall be defined in the FOM.

         HLA提供了访问RTI服务的标准接口，盟员使用这些标准接口与RTI交互(IEEE P1516.1)标准。接口规范定义了盟员应怎样与RTI交互。由于RTI及其服务接口需要面对具有多种数据交换方式的各类仿真系统，因此HLA没有对需要交互的数据做任何规定。应该在FOM中定义盟员间的数据交换。

By requiring a standardized,common interface between federates and the RTI, along with a common applicationprogram interface (API), the HLA allows for independent development andimplementation. Simulations can work independently and develop interfaces tothe RTI without regard to RTI implementation, and RTI developments can proceedwithout explicit consideration of simulation development. The separation of theinterfaces from the requirements for federate data exchange allows for thereuse of a common interface specification across the broad spectrum ofdistributed M&S applications, with specific application needs tailoredthrough the FOM mechanism.

RTI要求盟员与RTI间统一的标准化接口和统一应用编程接口(API)，标准化的接口使得开发仿真系统时不需要考虑RTI的实现，开发RTI与开发仿真应用可独立进行。接口与盟员数据交互需求分离使得异构分布式M&S应用系统可以重用统一的接口规范，在FOM机制下，特殊应用还可进行裁剪。

 

R5、The HLA shall allow fordifferent federates to own different attributes of the same object instance(e.g., a simulation of an aircraft might own the location of the airbornesensor while a sensor system model might own other instance attributes of thesensor). To ensure data coherency across the federation, the HLA shall allow atmost one federate to own (have the right to change the value of) the attributeof an object instance at any given time. The HLA shall also provide the mechanismto transfer ownership, dynamically during execution, from one federate toanother.

         HLA允许同一个对象不同属性的所有权（在此，“所有权”定义为拥有更新实例属性值的权利）分属于不同的盟员，但为了保证联盟的数据一致性，给出了本规则。根据该规则，对象实例的任何一个实例属性，在联盟执行的任一时刻只能为一个盟员所拥有。此外，HLA还提供了将属性的所有权动态地从一个盟员转移到另一个盟员的机制。

By defining ownershipat the instance attribute level and providing the tools to hand off ownershipduring execution, the HLA provides a flexible toolset for using variouscombinations of simulations to meet user needs.

通过定义实例属性等级的所有权和提供联盟执行期间传递所有权的工具，HLA提供了可用于不同组合盟员的可伸缩工具集来满足用户的需求。

 

R6、Federates shall be defined assimulations (a method for implementing a model over time) or other applications(including simulation managers, data collectors, live entity interfaces, andpassive viewers) participating in a federation. The HLA shall require that eachfederate have an HLA simulation object model (SOM). The HLA SOM shall includethose object classes, class attributes, and interaction classes of the federatethat can be made public in a federation.

The HLA shallnot prescribe which data are included in the SOM; this shall be theresponsibility of the simulation developer. The HLA shall require that SOMs bedocumented in the prescribed format (HLA OMT).

A major goal ofthe HLA is to support interoperability and reuse of simulations. The HLA shallprovide this support by providing reuse at the level of simulations (or, moregenerally, federates), allowing access to the representations in thosesimulations. Lack of cost-effective access to information about the object representationsavailable in federates inhibits reuse.

Therequirement  for a SOM addressesinformation access by requiring federates to document the minimum essential,salient aspects of their capabilities to allow for easy identification of thefederate’s potential application in new federations. Although the full set ofinformation required by a potential user will go well beyond the SOM contents,providing easy access to characterizations of simulations based on reusepotential will enable users to decide more effectively whether to invest infurther assessment of the simulations to their applications. The HLA is basedon the premise that developing and maintaining an accurate and usable statementof information supporting reuse is a high priority for individual simulationdevelopers, whose success will be measured in part by the extent to which theirsimulation supports a wide variety of user applications.

盟员可以定义为参与联邦的仿真应用或其他的拥有程序（如仿真管理器、数据记录器、尸体接口代理等），HLA要求每个联邦成员有一个成员对象模型(simulationobject model, SOM)，该SOM描述了盟员能在联盟中公布的对象类、对象类属性和交互类，但HLA并不要求SOM描述具体的交互数据，数据描述是盟员开发者的责任。HLA要求SOM必须按HLA OMT规定的格式规范化。HLA的主要目的是重用，这种重用通过支持成员级的重用来实现的。尽管在SOM中包含盟员的完整信息有助于该盟员适应不同仿真目的的联盟，但如果因此而使得对盟员中对象实例的可用信息不能有效访问，那么SOM将无法重用。因此为了满足这种要求，盟员的SOM通常只包括反映盟员主要特征的信息集合，以支持其他盟员对该盟员信息有效访问，该信息集合包括反映盟员主要特征的信息。当然，对于个别仿真开发者来说，开发和维护精确、有效的、支持重用的完整信息，可能具有更高的优先级。

 

R7、The HLA shall allow federatesto make object representations and interactions developed for internal useavailable as part of federation executions for external use with objectsrepresented in other federates. These capabilities for external interactionshall be documented in the SOM for the federate. These federate capabilitiesshall include the obligation to export updated values of instance attributesthat are calculated internally in the federate and the obligation to be able toexercise interactions represented externally (i.e., by other federates in afederation). By designing federates from the outset with the ability to presentinternal objects/attributes/interactions as public, the mechanisms for reuse ofthe simulation will be in place from the start.

         HLA要求盟员在其SOM中描述，供其再仿真运行过程中使用的对象类和交互类，同时允许为某个盟员开发的对象类可被联盟中其他盟员所使用。联邦成员的SOM将这些对外交互的能力规范化，这些能力包括更新在盟员内部计算的实例属性值和向其他盟员发送交互实例。在SOM开发过程中，如果从一开始就将盟员内部的对象类、对象类属性和交互类设计为可对外公布，这样就可实现仿真的重用机制。

 

R8、The HLA shall allow fordifferent federates to own different attributes of the same object instance(e.g., a simulation of an aircraft might own the location of the airbornesensor while a sensor system model might own other instance attributes of the sensor).With this capability, it shall be possible to allow a simulation designed for onepurpose to be coupled with one designed for another purpose to meet a newrequirement. By building in the capability to transfer and accept ownership ofinstance attributes, simulations designed in accordance with the HLA providethe basic structural tools to become federates in the widest possible range offuture federations. The instance attributes of a federate that can be eitherowned or reflected, and that can be dynamically transferred during execution,are documented in the SOM for that federate.

         HLA允许不同的盟员拥有同一对象实例的不同实例属性。这样，为某个目的设计的盟员可以用于另一目的的联盟。在盟员成员的SOM中，将盟员的对象类属性规范化，盟员就可以动态地接受和转移这些实例属性的所有权，通过赋予盟员转移和接收实例属性所有权的能力，使得一个盟员可以广泛地应用于其他联盟。

 

R9、The HLA shall permit federatesto own (i.e., produce updated values for) attributes of object instancesrepresented in the simulation and then make those values available to otherfederates through the RTI. Different federations may specify differentconditions under which instance attributes will be updated (at some specifiedrate, when the amount of change in value exceeds a specified threshold such asaltitude changes of more than 1000 feet, etc.) . Widely usable simulationsshall be able to adjust the conditions under which they export their publicinstance attributes to support the requirements of different federations. Theconditions applicable to the update of specific instance attributes of afederate shall be documented in the SOM for that federate.

         HLA允许盟员拥有对象实例的实例属性，并能通过RTI将这些属性的值传递给其他盟员。不同的联盟可规定不同的实例属性更新条件（比如，高度变化超过1000米等）。盟员应该具有调整这些条件的能力，这样，通过设定不同的更新条件，盟员可以输出不同范围的实例属性值以满足不同联盟的需要。对于一个盟员而言，应该在它的SOM中将实例属性值的更新条件规范化。

 

R10、The HLA time-managementstructure is intended to support interoperability among federates using differentinternal time-management mechanisms. The HLA shall support these capabilitiesprovided that federates adhere to certain requirements necessary to realizeeach service. To achieve these goals, a single, unifying approach to time managementis being developed to provide time-management interoperability among disparatefederates. Different categories of simulations are special cases in thisunified structure, and typically use only a subset of the RTI’s full capability.Federates need not explicitly indicate to the RTI the time-flow mechanism (timestepped, event driven, independent time advance) being used within thefederate, but shall utilize the RTI services (including time management) thatare appropriate for coordination of data exchange with other federates.

         HLA的时间管理方法支持使用不同内部时间管理机制的盟员间的互操作。为了达到这一目标，HLA提供统一的时间管理服务来保证不同盟员间的互操作，因此不同类型的仿真只是HLA时间管理方法的一个特例，一般只使用了RTI时间管理能力的一部分。盟员不需要明确告诉RTI其内部使用的时间推进方式，但它必须使用各式的RTI服务（包括时间管理服务）来与其他盟员进行数据交互。