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The Controls Middleware (CMW) project was launched over ten years ago. Its main goal was to unify middleware solutions used to operate CERN accelerators. An important part of the project, the equipment access library RDA, was based on CORBA, an unquestionable standard at the time. RDA became an operational and critical part of the infrastructure, yet the demanding run-time environment revealed some shortcomings of the system. Accumulation of fixes and workarounds led to unnecessary complexity. RDA became difficult to maintain and to extend. CORBA proved to be rather a cumbersome product than a panacea. Fortunately, many new transport frameworks appeared since then. They boasted a better design, and supported concepts that made them easy to use. Willing to profit from the new libraries, the CMW team updated user requirements, and in their terms investigated eventual CORBA substitutes. The process consisted of several phases: a review of middleware solutions belonging to different categories (e.g. data-centric, object-, and message-oriented) and their applicability to a communication model in RDA; evaluation of several market recognized products and promising start-ups; prototyping of typical communication scenarios; testing the libraries against exceptional situations and errors; verifying that mandatory performance constraints were met. Thanks to the performed investigation the team have selected a few libraries that suit their needs better than CORBA. Further prototyping will select the best candidate.
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