Application Level Events
Application Level Events (ALE) is a standard created by EPCglobal, an organization of industry leaders devoted to the development of standards for the Electronic Product Code (EPC) and Radio Frequency Identification (RFID) technologies and standards. The ALE specification is a software specification indicating required functionality and behavior, as well as a common API expressed through XML Schema Definition (XSD) and Web Services Description Language (WSDL). Introduction. RFID has the potential to generate a massive amount of data in a typical production environment. Attempts by a business application to process such a huge amount of data would be  impractical and, at worst, could ultimately cripple the application itself. This is where the ALE specification comes in. It defines a configurable set of data gathering techniques that higher order business applications can then use to receive more specialized set of tags to process. ALE provides for a standard way to describe and define these data gathering techniques to help decouple a business application from the source of its RFID data. Using ALE, the application provides a high-level description of what operations it wants to perform on the tags (e.g., Read, write, lock or kill operations for a C1G2  tag), with additional restrictions such as boundary conditions, filtering conditions and reporting conditions. The ALE implementation then finds the most appropriate way to fulfill such requests, interacting with RFID readers or other devices as necessary. Application writers are shielded from details of device configuration and management, and may rely upon the ALE implementation to handle data conversions including those specified by EPC and ISO data standards. ALE Versions. ALE 1.0 was the first software specification to be ratified by EPCglobal in September 2005. The next version, ALE 1.1 extends over ALE 1.0 and adds a host of new features. This  version is ratified by EPCglobal in February 2008.