The Application Level Events standard specifies an interface through which clients may obtain filtered, consolidated data capture information for physical events and related data from a variety of sources.
ALE provides a starting point for writing business logic, because it hides a lot of low level details. In particular, ALE clients do not need to know which make or model of reader is being used or even how many readers or antennas are in use. ALE delivers decoded data (e.g., an EPC URI) rather than the raw binary contents of tags. Additionally, an ALE client only needs to specify its information requirements (e.g., “give me a report once a minute of all new item-level tags that pass through loading door #5”), allowing the ALE implementation to figure out the best way to fulfill that request using the capabilities of the underlying readers. This function is implemented by running an “ALE filtering and collection engine”, which can be obtained from certain reader vendors and also software vendors who specialize in RFID middleware. There is also an open-source ALE engine which can be downloaded from the Fosstrak ALE site. The ALE engine works as background process and provides a web-based Application Programming Interface (API) to user applications. ALE includes features both for reading and writing RFID tags.