CAREER: An Evolvable Architecture for Internet Data Transfer

随着互联网的迅速普及，对已建立的互联网架构及其核心协议进行更改变得越来越困难。更改可能需要修改部署在数亿台计算机上的数十或数百个软件实现。除了大规模之外，这些更改难以部署的一个主要原因是应用程序与底层网络协议及其语义之间的高度耦合。这种耦合对于主要作为数据传输代理的一类重要网络应用程序（例如，电子邮件、文件传输、web等）来说是显而易见的。这些应用程序通常捆绑了内容协商（命名对象、协商通用语言、处理cookie等）和数据传输（实际通过网络发送数据的过程）的功能。这种耦合的结果是，为了部署新的数据传输机制，必须修改使用网络的每个应用程序。智力优势：首席研究员建议设计和实现一个新的面向数据的传输层，代表应用程序执行数据传输。传输层将是一个窄腰，在这个窄腰上引入新的数据传输机制，并使它们立即使使用传输层的所有应用程序受益。通过作为修改的场所，传输层还将促进底层网络中更改的采用。一个新的传输层模块将能够使应用程序的网络密集型部分使用新的网络层功能，而无需对应用程序进行修改。作为传输层的首次使用，该项目将开发新的技术，以提高互联网应用程序对具有挑战性的网络环境的弹性。这些环境的特点是间歇性连接或链路质量差，例如由廉价无线链路或卫星提供的连接。所开发的技术将用于创建一个在面对意外和恶意故障时性能大大提高的网络。该项目将探索的方法包括通过并行使用多个网络路径来执行传输，通过便携式存储支持带外传输，并确保在面对网络中断时传输继续向前发展。该项目将解决构建和部署实用的传输服务的几个主要挑战。首先是传输服务提供给应用程序的接口的设计和评估。设计必须同时自然地适应现有和未来的应用程序，同时不排除在生产环境中使用所需的优化。第二个挑战是安全模型的开发和实现，该模型要平衡提供同等或更好的安全性的需求，同时允许有效的实现。适当的安全模型可能需要开发新的技术来安全地共享缓存的数据。第三个挑战是设计算法，以便在传输层将启用的不同数据源中进行选择。这些算法必须对不断变化的网络条件做出反应，并在具有令人难以置信的不同性能特征的共享路径之间保持平衡。更广泛的影响：持续的发展对于使互联网及其协议适合更多的应用程序，特别是那些需要比今天的互联网提供更多可用性的应用程序至关重要。改进的协议还可以显著降低与管理Internet相关的操作成本。这项研究可能会显著加快新协议和新技术的采用速度，因为它提供了一个狭窄的接口，开发人员可以集中精力，而不是将精力分散到几十个不同的应用程序上。作为这项研究的一部分，为在具有挑战性的环境中进行通信而开发的技术可以帮助提高互联网的可用性，并将其扩展到以前网络连接服务很差的地区。该项目将发布一个免费的传输服务参考实现，供其他人使用。PI将使用在这项研究过程中开发的框架作为CMU即将到来的研究生课程的核心部分。如果成功部署，传输框架将被用作一种工具，将PI课程中的课程内容（幻灯片、笔记、作业和每堂课的视频）在互联网上免费提供给网络连接不佳的服务欠缺地区的学生。

Making changes to the established Internet architecture and its core protocols has become increasingly difficult as the Internet has exploded in popularity. Changes may require modifying dozens or hundreds of software implementations deployed on hundreds of millions of computers. Other than sheer scale, a major reason that these changes are difficult to deploy is a high degree of coupling between applications and the underlying network protocols and their semantics. This coupling is evident for an important class of network applications that function primarily as data transfer agents (e.g., email, file transfer, web, and so on). These applications typically bundle the functions of content negotiation---naming objects, negotiating common languages, handling cookies, etc.---and data transfer---the process of actually sending the data across the network. The result of this coupling is that in order to deploy a novel data transfer mechanism, one must modify every application that makes use of the network.Intellectual Merit:The Principal Investigator proposes to design and implement a novel data-oriented transfer layer that performs data transfer on behalf of applications. The transfer layer will be a narrow waist at which to introduce new mechanisms for data transfer, and have them immediately benefit all applications using the transfer layer. By serving as a locus for modifications, the transfer layer will also facilitate the adoption of changes within the underlying network. A new transfer-layer module will be able to make the network-intensive portion of applications use new network-layer functionality with no application modification.As a first use of the transfer layer, this project will develop novel techniques for improving the resilience of Internet applications to challenging network environments. These environments are characterized by intermittent connectivity or poor link quality, such as that provided by cheap wireless links or satellites. The techniques developed will be used to create a network that performs drastically better in the face of accidental and malicious failures. The approaches the project will explore include performing transfers by using multiple network paths in parallel, supporting out of band transfers via portable storage, and ensuring that transfers continue to make forward progress in the face of network interruptions. This project will address several major challenges to building and deploying a practical transfer service. The first is the design and evaluation of the interface that the transfer service provides to applications. The design must simultaneously fit naturally into existing and future applications, while not precluding the optimization necessary for its use in a production environment. The second challenge is the development and implementation of a security model that balances the need to provide equivalent or better security while allowing an efficient implementation. The appropriate security model will likely require the development of novel techniques for securely sharing cached data. The third challenge is the design of algorithms to select among the different sources of data that the transfer layer will enable. These algorithms must react to changing network conditions and balance between shared paths with incredibly different performance characteristics.Broader Impact:Continued evolution is critical for making the Internet and its protocols suitable for more applications, particularly those that require more availability than today's Internet can provide. Improved protocols may also significantly reduce the operational costs associated with managing the Internet. This research may significantly accelerate the rate of adoption of new protocols and technologies by providing a narrowed interface on which developers can concentrate, instead of spreading their effort across dozens of different applications. The techniques developed as a part of this research for communication in challenging environments could help improve the availability and reach of the Internet into areas formerly only poorly served by network connectivity. The project will release a freely available reference implementation of the transfer service for others to build upon.The PI will use the framework developed in the course of this research as a central part of an upcoming graduate class at CMU. If successfully deployed, the transfer framework will be used as a vehicle for making course content (slides, notes, assignments, and videos of each lecture) from the PI's classes freely available on the Internet in a way that is accessible to students in underserved areas with poor network connectivity.