STI: NetReact Services: Middleware Technologies to Enable Real-time Collaboration across the Internet

现代科学是一个分布式的广域企业，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人员团队。任何此类实时和数据密集型协作的高带宽网络需求都会给最大的网络管道带来负担，当通过互联网传输时，它们的千兆位/秒数据流必须使用网络链路速度从10Gbps到10 Mbps不等的异类平台，以及从台式PC到大型超级计算机的最终用户机器。然而，有效的科学协作要求团队成员能够彼此实时交互，并与关键远程资源进行实时交互，尽管平台的异构性和平台资源的可用性存在动态变化。NetReact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提高最终用户的性能，并弥补网络能力的潜在不足。NetReact提供了丰富的功能，用于响应网络和平台监控动态重新配置中间件和应用程序，并协调(1)中间件和应用层对网络状态变化的反应，(2)在传输层可能同时采取的动作。NetReact的监控(NRM)服务动态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，甚至为正在进行的基于中间件的科学协作动态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NetReact丰富的中间件的功能得到了显著改进，使最终用户即使在无法访问高端机器或大容量网络链路的情况下也能够实时协作，从而支持目前仍无法使用现有网络和网格计算技术的科学应用。

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.