ITR: Collaborative Research: Morphable Software Services: Self-Modifying Programs for Distributed Embedded Systems

未来的嵌入式系统应用和基础设施将越来越动态。此外，在这些基础设施中使用的设备将有很大的不同，从传感器和嵌入式设备，到手持设备，到高端服务器系统，所有这些设备都在不断地交互，以便从产生信息的地方收集、整理和传递信息到需要它的地方。该项目通过开发集成了计算机科学多个领域的新信息技术，包括计算机体系结构、操作和实时系统、编译器和中间件，解决了分布式嵌入式系统的动态特性。关键意图是创建可变形的嵌入式服务，即不断自我修改和适应的服务，以满足动态应用程序需求和环境/资源限制，包括电力预算、端到端服务质量（QoS）保证(例如。（时间约束）和安全性约束。有许多有用的可变形服务的例子。以有限的形式，它们已经出现在今天的手机平台上，例如，终端用户可以动态下载新的戒指或获取新的游戏（可能取代现有的游戏），等等。然而，服务变形远远超出了这样的配置能力。想象一下，例如，一部手机可以动态地变成一根便携式魔杖，利用它的传感（例如，它的内置摄像头）和通信能力（例如，通过与附近的其他手机互动）来引导它的主人离开灾难现场。然后，与这种以功能为中心的变形相反，考虑到这款手机利用附近服务器系统（或其他手机）的功率为用户提供适当级别的服务，尽管它的功率很低。这可以实现，例如，通过动态卸载服务到其他平台，通过（重新）划分跨设备和合作的服务器系统的服务，和/或通过部署更节能，也许，更少的图形功能的服务代码到手机本身。我们工作的另一个有趣的方面是，它能够超越性能和功率作为未来系统的唯一关键元素。例如，通过我们的方法，编译器方法和中间件可以用来增强信息安全，而不是系统性能。这可以通过散射关键应用状态来减少其暴露于外部入侵来实现。因此，信息安全可以成为应用程序QoS需求的一个组成部分。以安全为中心的服务变形的一个具体例子是在多个协作的分布式平台上“分散”关键和易受攻击的值，并在编译器控制下将它们“组装”到应用程序所需的程度。此外，当“汇编”值的最后一次使用完成时，“汇编”值将被销毁。对“汇编”值的每次使用都由编译器生成的代码进行验证。例如，考虑使用用于验证事务的社会安全号码的最后四位数字。整个社会安全号码永远不会作为一个值（可能被黑客入侵）存储在内存位置中。该值将以一种只有编译器知道的形式分散，然后编译器将使用这种形式及时地“组装”该值，以满足使用范围。本研究将开发的不同服务变形技术包括动态组件（重）部署、（重）专门化和（重）分区。这些操作由系统级机制支持，这些机制有效地携带运行时组件变形所需的性能、使用和需求信息，主要处理组件的处理和通信操作。其目的是使自修改组件能够获取有关当前资源可用性和服务质量需求的运行时信息。在开发这些软件技术的同时，我们将同时探索新的特定应用技术和方法，利用可变形软件服务，针对遥感和自主机器人应用。最后，虽然我们的大部分工作将利用当前的嵌入式系统平台，使用XScale板，我们也将考虑如何进一步改进硬件平台，以更好地实现可变形服务。这样的工作本质上拓宽了可变形服务能够运行的优化空间。我们的技术方法集成了多个CS学科，例如，通过利用有关计算机体系结构的详细知识（例如，与内存占用相关的功率使用）来开发编译器技术，从而动态生成具有更适合当前应用程序需求的功能和性能/功率配置文件的代码。编译器级和体系结构知识作为中间件级的元信息进行维护，轻量级中间件动态地将新变形的代码部署到目标平台。内核级机制收集和分发这些操作所需的资源信息。它们还有助于将应用程序级别的操作与正在执行的系统级别的操作集成在一起，后者在满足某些端到端约束时尤为重要。（时间或功率限制），这是分布式嵌入式应用所需要的。本研究的一个关键目标是证明可变形服务对关键应用的重要性和效用。这意味着需要与可变形服务技术共同开发应用技术和理念。通过将我们的研究立足于一个具有挑战性的应用领域，即在紧急管理情况下使用的自主机器人，我们的技术解决方案必须“闭环”，集成有关资源约束的系统级信息，中间件级选项来改变服务，以及应用级机会来权衡和选择如何最好地满足当前需求。其结果是，在系统中，应用程序需求的变化导致新的代码模块的部署和专门化，以满足这些需求，以及底层系统配置和属性的变化。换句话说，应用程序和系统不断“变形”，以最好地匹配最终用户的需求。将应用级研究扩展到利用服务变形的一个具体例子是在自主机器人中扩展以任务为中心的“价值”概念。在机器人技术中，“价值”指的是单个机器人对机器人团队任务的贡献，“价值”帮助机器人确定下一步的行动。我们的新研究将扩展这些解决方案：机器人不仅考虑运动选择，还将考虑其他活动的“价值”，如通信、计算和观察。该方法在很大程度上取决于该提案的其他组件，即qos管理和合作服务变形，以便机器人团队可用的通信链路和解释分布式传感器输入所需的CPU功率可以适当地部署。

Future embedded system applications and infrastructures will beincreasingly dynamic. Moreover, the devices used in such infrastructureswill vary widely, from sensors and embedded devices, to handhelds, to high endserver systems, all of which interact continuously in order to collect,collate, and deliver information from where it is produced to where it isneeded. This project addresses the dynamic nature of distributed embeddedsystems, by developing new information technologies that integrate acrossmultiple areas of Computer Science, including computer architecture, operatingand real-time systems, compilers, and middleware. The key intent is to createmorphable embedded services, that is, services that continuously self-modifyand adapt in order to meet dynamic application needs and environmental/resourceconstraints, including power budgets, end-to-end quality of service (QoS) guarantees(e.g., timing constraints), and security constraints.There are many Useful examples of morphable services. In limited forms, theyare already present in today's cellphone platforms, for instance, where end usersdynamically download new rings or acquire new games (possibly displacing existingones), etc. Service morphing, however, goes much beyond such configurationcapabilities. Imagine a cellphone, for example, which dynamically morphs intoan portable wand, using its sensing (e.g., its built-in camera) andcommunication abilities (e.g., by interacting with other nearby phones)to guide its owner out of a disaster site. Then, in contrast to suchfunctionality-centric morphing, consider this cellphone drawing on thepower of nearby server systems (or other phones) to provide suitable levelsof service to its user, despite the fact that its power is running low. Thiscan be done, for instance, by dynamically offloading services onto otherplatforms, by (re)partitioning services across the device and cooperating serversystems, and/or by deploying more power-efficient and perhaps, less graphics-capableservice code to the phone itself. Another interesting aspect of our work is itsability to go beyond performance and power as the only critical elements of futuresystems. With our approach, for instance, compiler methods and middleware can be usedto enhance information security rather than system performance. This can be doneby scattering critical application state to reduce its exposure toexternal intrusions. As a result, information security can become an integralelement of the QoS needs of applications.A concrete example of security-focused service morphing is to `scatter'critical and vulnerable values across multiple cooperating distributedplatforms and to `assemble' them only to the extent needed by the applicationunder compiler control. Moreover, when the last use of the `assembled'value is complete, the `assembled' value is destroyed. Each use of an `assembled' value is verified by compiler-generated code that authenticates it. For example, consider the use of last four digits of the social security numberused for authenticating a transaction. The entire social security number willnever be stored in a memory location as a value (that could be hacked into).The value will be scattered in a form known only to the compiler which it willthen use to `assemble' the value just in time only for the extent of the use.The different service morphing techniques to be developed in this researchinclude dynamic component (re)deployment, (re)specialization, and (re)partitioning.Such actions are supported by system-level mechanisms that efficiently carry theperformance, usage, and requirements information needed for runtime component morphing,principally addressing components' processing and communication actions.The intent is for self-modifying components to be able to acquire runtimeinformation about current resource availabilities and Quality of Servicedemands. While developing these software technologies, we will concurrentlyexplore new application-specific techniques and methods that take advantageof morphable software services, targeting remote sensing and autonomous roboticsapplications. Finally, while most of our work will utilize current embeddedsystems platforms, using XScale boards, we will also consider how tofurther improve hardware platforms to better enable morphable services.Such work essentially broadens the optimization space in which morphableservices are able to operate.Our technical approach integrates across multiple CS disciplines, by exploiting,for instance, detailed knowledge about computer architecture (e.g., power usagerelated to memory footprint) to develop compiler techniques that dynamically generatecode with functionality and the performance/power profiles more suitable tocurrent application needs. Compiler-level and architectural knowledge is maintainedas meta-information at the middleware level, and lightweight middleware dynamicallydeploys newly morphed code to target platforms. Kernel-level mechanisms collect anddistribute the resource information needed for such actions. They also help integratethe application-level with the system-level actions being taken, the latter beingparticularly important when satisfying certain end-to-end constraints(e.g., timing or power constraints) desired by distributed embedded applications.A key goal of this research is to demonstrate the importance and utility ofmorphable services for critical applications. This implies the need tojointly develop application techniques and ideas with morphable service technologies.By grounding our research in a challenging application domain, autonomous robots used inemergency management situations, our technological solutions must ``close the loop'',integrating system-level information about resource constraints, withmiddleware-level options to morph services, with application-level opportunitiesfor making tradeoffs and choices about how to best meet current requirements.The result are systems in which changed application needs result in new codemodules deployed and specialized to meet these needs, jointly with changes inunderlying system configurations and properties. In other words, applications andsystems are continuously `morphed' to best match end user requirements.A concrete example of extending application-level research to exploitservice morphing is to extend mission-centric notions of `value' in autonomousrobots. In robotics, `value' captures an individual robot's contribution to a missionundertaken by a robot team, and `value' helps a robot determine its next actions.Our new research will extend these solutions: instead of considering onlymovement alternatives, the robots will also consider the `values' ofother activities like communication, computation and observation. This approachdepends significantly on other components of this proposal, namely QoSmanagement and cooperative service morphing, so that the communication linksavailable to a robot team and the CPU power needed for interpreting distributedsensor inputs can be deployed appropriately.