Design and Implementation of ALE v1.1 Middleware in RFID systems

RFID technology has become popular and its application area has been expanding from business to public facilities to even daily activities. Generally, RFID system has four components: tags, reader devices, a middleware, and applications. EPCglobal has proposed the standard specification for the components and the interfaces between them. The ALE (application level events) is a de facto standard of RFID middleware defined in EPCglobal architecture framework. This paper describes the overall functions of the RFID components and mainly focuses on the design and implementation of the ALE version 1.1 which includes five groups of APIs to deal with readers and tags. This paper illustrates the detailed internal structure of the ALE implementation and the operation sequence diagrams with related XML scripts. This paper may help understanding the design and implementation of the enhanced middleware features.