CAREER: An Evolvable Architecture for Internet Data Transfer

随着互联网的普及，改变现有的互联网架构及其核心协议变得越来越困难。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。除了纯粹的规模，这些更改难以部署的一个主要原因是应用程序和底层网络协议及其语义之间的高度耦合。这种耦合对于主要用作数据传输代理的一类重要的网络应用(例如，电子邮件、文件传输、网络等)来说是显而易见的。这些应用程序通常捆绑内容协商的功能-命名对象、协商公共语言、处理Cookie等-以及数据传输-实际通过网络发送数据的过程。这种耦合的结果是，为了部署新的数据传输机制，必须修改每个利用网络的应用程序。智力优势：首席调查员建议设计和实现一个新的面向数据的传输层，它代表应用程序执行数据传输。传输层将是引入新的数据传输机制的狭窄腰部，并使它们立即使使用传输层的所有应用程序受益。通过充当修改的场所，传输层还将促进底层网络内的更改的采用。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，而不需要修改应用程序。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。这些环境的特点是断断续续的连接或糟糕的链路质量，例如由廉价的无线链路或卫星提供的环境。开发的技术将被用来创建一个在面对意外和恶意故障时表现得更好的网络。该项目将探索的方法包括使用多个网络路径并行执行传输，通过便携式存储支持带外传输，以及确保传输在网络中断的情况下继续向前推进。该项目将解决建立和部署实际转账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，同时不排除在生产环境中使用所需的优化。第二个挑战是制定和实施一种安全模式，在提供同等或更好的安全的需要之间取得平衡，同时允许有效实施。适当的安全模型可能需要开发用于安全共享缓存数据的新技术。第三个挑战是如何设计算法，以便在传输层将支持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，并在具有惊人不同性能特征的共享路径之间进行平衡。广泛影响：持续发展对于使互联网及其协议适用于更多应用至关重要，尤其是那些需要比今天的互联网提供更高可用性的应用。改进的协议还可以显著降低与管理互联网相关的运营成本。这项研究可能会显著加快新协议和技术的采用速度，因为它提供了一个较窄的接口，供开发人员集中精力，而不是将他们的努力分散到数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改善互联网的可用性和覆盖范围，使之进入以前网络连接服务不足的地区。该项目将发布免费提供的传输服务的参考实现，供其他人参考。PI将使用在此研究过程中开发的框架作为即将在CMU举行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媒介，用于在互联网上免费提供PI课程的课程内容(幻灯片、笔记、作业和每堂课的视频)，使网络连接较差的服务不足地区的学生能够访问。

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.