STI: Collaborative Research: NetReact Services: Middleware Technologies to Enable Real-time Collaboration Across the Internet

现代科学是一项分布式的广域事业，需要实时协调不同地点甚至不同大陆的科学仪器和遥感器、计算资源、大型数据存储库和研究团队。任何这种实时和数据密集型协作的高带宽网络需求都对最大的网络管道造成了负担，并且当在互联网上进行时，它们的千兆/秒数据流必须利用网络链接速度从10Gbps到10Mbps不等的异构平台，并且终端用户机器从台式电脑到大型超级计算机不等。然而，有效的科学协作要求团队成员能够相互交互，并实时地与关键的远程资源进行交互，尽管平台存在异质性，并且平台资源的可用性存在动态变化。nettreact中间件服务的关键思想是利用与分布式协作相关的大量服务器和处理资源来改进最终用户性能并弥补网络功能中的潜在缺陷。NetReact提供了丰富的功能，可以动态地重新配置中间件和应用程序，以响应网络和平台监控，并协调(1)中间件和应用程序级别对网络状态变化的反应，以及(2)传输级别可能同时采取的操作。NetReact的监控（NRM）服务动态地确定可用的网络带宽和通信延迟。NetReact使用这些信息来调整中间件和应用程序操作，调整底层网络传输，甚至动态地为正在进行的支持中间件的科学协作选择合适的网络路径。通过将NetReact服务嵌入到通常用于科学协作的网格计算中间件中，这种富含NetReact的中间件的功能得到了实质性的改进，使最终用户即使在没有访问高端机器或大容量网络链接的情况下也能实时协作，从而支持目前现有网络和网格计算技术无法实现的科学应用。

Modern science is a distributed wide-area enterprise, requiring real-time coordination of scientific instruments and remote sensors, computational resources, large data repositories and teams of researchers in different locations, even on different continents. The high-bandwidth networking demands of any such real-time and data-intensive collaborations tax the largest network pipes, and when conducted across the Internet, their Gigabit/sec data streams must utilize heterogeneous platforms with network link speeds that vary from 10Gbps to 10Mbps and with end user machines that range from desktop PCs to large supercomputers. However, effective scientific collaboration demands that team members be able to interact with each other and with critical remote resources in real-time, despite platform heterogeneity and despite dynamic variations in the availability of platform resources.The key idea of the NetReact middleware services is to utilize the substantial server and processing resources associated with distributed collaborations to improve end user performance and compensate for potential deficiencies in network capabilities. NetReact provides rich functionality for dynamically reconfiguring both middleware and applications in response to network and platform monitoring, and to coordinate (1) middleware and application-level reactions to changes in network state with (2) the possibly simultaneous actions taken at the transport level. NetReact's monitoring (NRM) services dynamically determine available network bandwidth and communication latencies. NetReact uses such information to adjust middleware and application actions, to tune the underlying network transport, and even to dynamically select suitable network paths for ongoing middleware-enabled scientific collaborations. By embedding NetReact services into the grid computing middleware commonly used for scientific collaboration, the functionality of such NetReact-enriched middleware is improved substantially, enabling end users to collaborate in real-time even when they do not have access to high end machines or high capacity network links, thereby supporting scientific applications that currently remain out of reach for existing networking and grid computing technologies.