Dynamic application composition for distributed systems

大多数人使用的软件被设计和打包为在单个设备上运行（例如，在个人计算机上运行的电子表格）。这种方法的应用通常限于高端科学和商业应用，这些应用不能在传统的台式机或个人计算设备（例如手机、PDA等）上运行。这种“标准”编程方法隐含地假设了一种基本的计算模型，其中所有的事情都在一台通用计算机上完成。然而，随着新的移动的和嵌入式设备的普及，这种模式正在悄然消失。越来越多地，这种相互连接的设备协同参与计算。这种现象的众多例子包括点对点文件共享应用程序和多用户游戏（大规模）以及在iPod、手机等上运行的多媒体工具（小规模）。 在这个建议中，我认为继续假设程序应该是在一台机器上运行的单一实体，并授权给特定的个人是过于限制，应该被取代。我建议一个替代模型的基础上可执行组件（即执行自包含功能的可运行程序），可以动态“组合”，以创建应用程序的飞行，是针对特定的用户和环境特征。这种动态构造的应用程序可以在广泛的互连设备上和跨广泛的互连设备更有效地运行。例如，考虑用户需要在使用具有有限能力的移动终端旅行时编辑文档的场景。通常，用户将不得不支付并预先安装大型、复杂且昂贵的应用程序，以支持在移动终端上编辑必要的文档。在我提出的方法中，只有软件的必要部分会根据需要动态组合，以便在移动终端上运行（如果需要，还可以在附近的一台或多台提供计算服务的机器上运行）。此外，组合软件可以进行定制，以适应小屏幕尺寸和设备无线连接到互联网的有限可靠性。

The software that most people use is designed and packaged to run on a single device (e.g. a spreadsheet running on a personal computer). Exceptions to this approach are normally restricted to high-end scientific and business applications that do not run on conventional desktop machines or personal computing devices (e.g. cell phones, PDAs, etc.). This "standard" programming approach implicitly assumes an underlying model of computing where everything is done on a single, general purpose computer. This model, however, is quietly fading as new mobile and embedded devices become prevalent. Increasingly, such interconnected devices are collaboratively involved in computations. Among the multitude of examples of this phenomenon are Peer-To-Peer file sharing applications and multi-user gaming (at the large scale) and multimedia tools running on iPods, cell phones, etc. (at the small scale).   In this proposal, I argue that continuing to assume that programs should be monolithic entities running on a single machine and licensed to specific individuals is overly restrictive and should be replaced. I suggest an alternative model based on executable components (i.e. pieces of runnable programs performing self-contained functions) that may be dynamically "composed" to create applications on the fly that are tailored to specific user and environmental characteristics. Such dynamically constructed applications can be run more efficiently both on and across a wide range of interconnected devices. For example, consider a scenario where a user needs to edit a document while travelling using a mobile device with limited capabilities. Normally the user would have to pay for and pre-install a large, complex and costly application to support editing the necessary document on the mobile device. In my proposed approach, only the necessary parts of the software would be dynamically composed on demand to run on the mobile device (and, if necessary, on one or more nearby machines offering compute services). Further, thecomposed software could be tailored to suit the small screen size and limited reliability of the device's wireless connection to the Internet.