DAP4: Overview

• The D4 spec is broken into two parts: The Data model and the Web services descriptions. In addition, there is a provision for extensions that cover additional behavior. Examples of likely extensions are JSON responses and Server processing operations.
• Metadata in one response
• Data model: Coverages, Groups, 64-bit integers, other types
• Checksums for all data responses
• Encoding of data responses
  • Reader makes right
  • reliable error delivery while returning data
• Constraints
  • Subsetting coverages
  • Filters are per variable
• DSR: per-dataset capabilities document; fixes an inconsistency when a 'bare URL' is dereferenced
• Asynchronous behavior
• Web services
  • Defines how the protocol is used with HTTP --> implies that we've thought explicitly about using it with other protocols