PCGAP: Pattern catalog for gis application programming

Geographic information systems (GIS) application programming at the component level is a challenge for students whose GIS backgrounds are established through software systems with command-level interfaces. The root of the problem is both conceptual and technical. Resolution of the problem requires assistance in making an association between previous knowledge and the new representation. This paper presents our experience in using Pattern Catalog for GIS Application Programming (PCGAP) to deal with this problem. PCGAP explicitly records the component-level implementation of command-level operations and helps users search for and retrieve patterns. A pattern is specified through sixteen elements from which seven are extracted to form an entry in the pattern catalog. PCGAP has three system components: pattern store, glossary, and client. These components communicate with each other through the network. Students interact with PCGAP through a graphical user interface (GUI), which provides the connection to pattern stores, pattern composition and editing, pattern search, and pattern output. PCGAP was evaluated through performance comparisons. The outcome was encouraging.