XL (XML programming language)

XL is an XML language used for implementation of web services. It was developed in 2001 by Daniela Florescu ( XQRL Inc. ), Andreas Grünhagen and Donald Kossmann (ETH Zurich ). XL is still in development and is based on the data model of XML. It supports the W3C standards, and uses inter alia XQuery as the query language, SOAP to communicate with other network services and WSDL to specify the interfaces.

XL is declaratively to a large extent, that is, in the language are in network services frequently recurring functions already implemented. These functions can be called by specifying keywords, the so-called Declarative Web Service Clauses. These include:

  • Storing entries of the clients ( logging)
  • Automatic new inquiries on failed request to another service (retry of Action )
  • Distribution to multiple systems ( Workload Management)
  • Automatic optimization of the code ( Performance Tuning )

By concentrating solely on XML as a data model computationally intensive transformations between type systems can be avoided. These conversions are necessary in current implementations in an object-oriented or procedural programming language in combination with a relational database.

XL integrated XML processing, storage, and communication in a modular scalable system. The current run-time environment has been implemented in Java. XL is not freely available. Comparable programming languages ​​include: WS -BPEL or (C- omega).