Customs Engine Domain-specific Languages in a Customs Information System Section Title

The literature offers many descriptions of the benefits of using DSLs, including improved development productivity, flexibility, maintainability, and separation of business and technical aspects. For instance, Don Batory and his colleagues report on their use of DSLs to implement a command-and-control simulator. 2 Their case study demonstrated added development productivity and flexibility with respect to a Java implementation. Arie van Deursen and Paul Klint reported using a DSL in the financial engineering domain with an emphasis on added maintainability. 3 Finally, Satish Chandra and his colleagues and Scott Thibault and his colleagues discuss case studies in which they used DSLs to implement video device drivers and distributed cache coherence protocols, respectively, demonstrating the benefits of separating technical aspects from business logic. 4,5 However, in spite of all this work, little evidence supports the applicability of DSLs in large-scale information systems development. This article addresses that gap by reporting on a successful case study in which DSLs served as a customs information system's backbone. Since 2005, Cybernetica AS has worked with the Estonian Tax and Customs Board in building Customs Engine (CuE), a suite of systems for processing customs documents (such as declarations, manifests , warehousing notices, and so on). Each type of document reflects a movement of goods—for example, between a ship and a warehouse—and is associated with its own set of rules, regulations, and procedures. Given the domain's document-heavy focus, the CuE development team (of which I was a part of) decided to decompose CuE into subsystems, such that each one is responsible for processing one type of document. CuE runs on standard Java EE application serv-ers. Much like Microsoft Office contains programs that are useful even if the rest of the suite isn't installed , each CuE subsystem is an independent application that can run separately. In addition to providing a user interface for manipulating certain documents, CuE subsystems communicate with other CuE subsystems and their counterparts in the EU to track movement of goods across several T hrough its use of appropriate notations and abstractions, a domain-specific language (DSL) offers expressive power focused on—and usually restricted to—a particular domain. 1 In other words, DSLs trade broad applicability for expressive power in a particular area. Classic examples include Unix makefiles (build scripts), regular expressions (for specifying text patterns), HTML (for describing text layout), and GraphViz (for describing graphs). Cybernetica AS's Customs Engine comprises several subsystems built on a …