PASS-a service for efficient large scale dissemination of time varying data using CORBA

A common class of wide-area distributed applications remotely collect time-varying data and send it to consumers around the network. Some examples of these include network management, stock ticker data and event logs. The environment in which these applications must operate often dictates the schemes for disseminating the data between the writers and the readers. If the transport channel can be optimized to match the application´s behavior patterns and the network resource constraints, sufficient improvements in application-level quality of service (QoS) can be achieved. The PASS (Piecewise Asynchronous Sample Service) system addresses this problem by using a flexible system of interconnected servers. PASS servers are distributed geographically around the network and are connected to readers and writers using the CORBA protocol. The forwarding policies used by the servers and the server interconnections can be customized for each application. Thus, PASS acts like an application-level multicast service with variable forwarding policies. PASS has been used to disseminate the up/down status of a large number of devices to a network management system. The PASS forwarding policy used very little network bandwidth while responding to failures in half a network round-trip time