Server architecture with detection and recovery of failed out-of-process application

Abstract

A server architecture has a server program to receive client requests and multiple applications to process the requests. Each application comprises a collection of agents that can be invoked to process the requests and an application manager that manages the collection of agents. The agents within the associated collection are independent from, but dynamically accessible by, the application manager. Depending on the request, the application manager selects one or more agents to generate content to be returned to the client. An application manager director manages the application managers and facilitates delivery of the client requests from the server program to the suitable application. The application managers are independent from, but dynamically accessible by, the application manager director. For a given request, the director selects the appropriate application manager to handle the request. The application manager, in turn, selects the appropriate agent to process the request. The applications, including the agents and associated application managers, can be run either in-process or out-of-process with the server program. The server architecture has a detection and recovery subsystem that detects when an out-of-process application crashes and then recovers the application from that crash. The subsystem logs requests when they are passed to the out-of-process application, and remove the requests from the log when responses to the requests are returned from the application. If the out-of-process application crashes while one or more requests are outstanding, those requests remain listed on the log and thus readily identifiable. During recovery, the subsystem cleans up the outstanding requests until the log is cleared. Thereafter, the subsystem restarts the failed application to restore the service.