These legacy applications need to be rewritten to access remote sources, or need to rely upon ad hoc intermediary applications that aggregate the data into a passive file before executing the legacy application. This paper presents a simple, elegant, programmable method for allowing natural integration of legacy applications into distributed system infrastructures. The approach called active files enables multiple information sources to be encapsulated as a local file that serves as their logical proxy. This local file is accessed though a sentinel process, which automatically starts when the file is opened, aggregates data from multiple sources, and filters all access to and from the file.
Active files find a variety of applications in both distributed and non-distributed systems.
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