Data Access Language: Difference between revisions

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'''Data Access Language''', or simply '''DAL''', was a [[SQL]]-like language parser released by [[Apple]] in the early 1990s1990 to provide unified [[client/server]] access to [[database management system]]s. AppleIt purchasedwas themarginally systemsupported fromin aan smallon-and-off vendorfashion until the mid-90s, whowhen calledmanagement itapparently '''CL/1'''grew (''commandbored languageof 1'')it priorand tosold theit purchaseoff.

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 was essentially a cut-down version of SQL, supporting only the most basic functionality, but adding clean syntax for cursor operations, logic, and loops. When sent a command the DAL interpreter broke down the statement and re-built it into subqueries for the underlying data sources. For instance, DAL users could write a single SQL query that would be applied to two physically separate databases, DAL would then produce smaller subqueries for each server, and combine the results on the way back. This is similar in nature to how [[Microsoft Access]] works, but provided at a system-wide level. In this respect DAL is much higher level in concept than systems like [[ODBC]] or [[JDBC]], which essentially define the "pipe" to the data source and little more.

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 (while almost certainly led to Apple's efforts). It appears to have seen little use, and theeventually productApple wassold eventuallyit soldto offIndependence againTechnologies in the1994, midduring a sell-90soff of a number of "high-end" packages such as an [[X.400]] server. In 1995 [[BEA Systems]] bought the company, neverand in turn sold it to be[[UniPrise]] seenin againlate 1996. During this period it was basically a dead product.

DAL was accessed through Apple's own ODBC-like driver layer, [[Data Access Manager]]. One of the more common uses was [[HyperCard]]. The combination of HyperCard and DAL presented a serious challenge to existing vendors who could offer nothing with a GUI, and soon [[Oracle]] purchased a HyperCard-clone, PLUS from [[Spinnaker Software]], to produce Oracle Card.

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. When sent a command the DAL interpreter broke down the statement and re-built it into subqueries for the underlying data sources. ForThis instance,translation DALtook usersplace couldon writethe aserver-side, singleunlike SQLmost querysimilar that would be applied to two physically separate databasestools, DALrequiring woulda thenfairly produceexpensive smaller"adaptor" subqueriesprogram forof eachdubious server, and combine the results on the way backperformance. This is similar in nature to how [[Microsoft Access]] works, but provided at a system-wide level.bit Inof thisarchitechture respectmade DAL isconsiderably muchless higherappealing levelthat in concept thansimilar systems like [[ODBC]], orwhere [[JDBC]],the whichtranslation essentiallynormally definetakes theplace "pipe" toon the dataclient sourceside and littleis moretypically "free".

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 (while almost certainly led to Apple's efforts). It appears to have seen little use, and the product was eventually sold off again in the mid-90s, never to be seen again.

On the client end, DAL was originally accessed directly through Apple'sa "system extension", but DAL was later rolled into a ownsingle ODBC-like driver layer, [[Data Access Manager]]. One of the more common usesclients was [[HyperCard]]. The combination of HyperCard and DAL presented a serious challenge to existing vendors who could offer nothing with a GUI, and soon [[Oracle]] purchased a HyperCard-clone, PLUS from [[Spinnaker Software]], to produce [[Oracle Card]].

[[Category:Failed Apple initiatives]]