Connecting ALMOST to the world around it: from Fortran file I/O to a service-oriented architecture

The Sonar group at TNO has been developing a computation kernel to estimate sonar performance for the last 30 years. This application, commonly referred to as ALMOST, is written in Fortran and interfaces with other applications through files. With the years, this interface had proven very limiting and hence the decision was made to replace it. There are few main requirements that shaped the design of the solution: a need for cross-language support (since ALMOST is in use in many contexts), a need for a network transport for the interface and the need for a solution that discouraged fragmentation. Furthermore, given that the accuracy of the results is of paramount importance, a comprehensive test-suite was also an important need. Therefore, the solution focuses on a service-oriented architecture, aimed at providing simple interfacing over network and language barriers and preventing fragmentation by exposing a language-agnostic interface. The subsequent layered interface consist of commands and parameters to isolate sections of Fortran code, followed by abstractions to facilitate extracting performance from the underlying calculations and finally by exposing a Thrift-based service interface that can be used from a long list of supported languages.