Data Access Language

Data Access Language, or simply DAL, was a SQL-like language parser released by Apple in 1990 to provide unified client/server access to database management systems.

DAL started as a 3rd party product, CL/1 (Connectivity Language One), from a small vendor, Network Innovations. Apple purchased the company in 1988, about the time that client/server databases were becoming a hot issue in the industry. They released their first version of the re-branded software in 1989, for MVS, and followed with other versions over the next year or so.

DAL suffered from most Apple problems of the early 1990s, notably a alternating level of support in which Apple would present the product and then ignore it. DAL's release was also coincident with Apple's fall from grace in the business world, and not coincidentially with Microsoft's ODBC efforts. It appears to have seen little use, and eventually Apple sold it to Independence Technologies in 1994, during a sell-off of a number of "high-end" packages such as an X.400 server. In 1995 BEA Systems bought the company, and in turn sold it to Uniprise in late 1996. During this period it was basically a dead product.

DAL was essentially a cut-down version of SQL, supporting only the most basic functionality, but adding clean syntax for cursor operations, logic, and loops -- at that time no real standards existed for this side of SQL programming. When sent a command the DAL interpreter broke down the statement and re-built it into subqueries for the underlying data sources. This translation took place on the server-side, unlike most similar tools, requiring a fairly expensive "adaptor" program of dubious performance. This bit of architechture made DAL considerably less appealing than later systems like ODBC, where the translation normally takes place on the client side and is typically "free".

On the client end, DAL was originally accessed directly through a "system extension", but DAL was later rolled into a single ODBC-like driver layer, Data Access Manager (DAM). DAM was ODBC-like in concept, but did not include the SQL layers, it was strictly a system for sending opaque queries and receiving result sets. DAM also included the concept of a "query document" that allowed the DAL (or other) queries to be written in an authoring system and then easily used in any client application.

For much of the 1990s a direct-DAL database server was available on the Macintosh, Butler. However, like any server software on the "classic" MacOS, Bulter was seriously hampered by the Mac's file system and could never really deliver the sort of performance the same server would have on Windows NT or Unix.

One of the more common clients for DAM was HyperCard. The combination of HyperCard and DAL presented a serious challenge to existing vendors who could offer nothing with a GUI. Apple gave a series of demos of HyperCard/DAL, and soon Oracle purchased a HyperCard-clone, PLUS from Spinnaker Software, to produce Oracle Card.