Generation of query and update views for object relational mapping
View Patent ↗A data access architecture may includes a mapping architecture for mapping data as may be used by an application to data as persisted in a database. Such a mapping architecture uses two types of “mapping views”—one for translating queries and the other for translating updates. A mechanism is provided that automatically generates query and update views from high-level mapping specifications. A validation may be performed to ensure that a mapping specification, when used in conjunction with a mapping architecture, allows data to “roundtrip” from the application to the database, without loss of data.
1. A method for providing data services to an application by a data access system, comprising:
receiving, by said data access system, a mapping specification, said mapping specification correlating an application schema associated with said application with a database schema associated with a database;
validating, by said data access system, that said mapping specification permits update data to losslessly roundtrip between said application and said database by:
verifying, by said data access system, that an update initiated by said application according to said application schema can be:
received by said data access system;
modified by said data access system utilizing said mapping specification; and
performed by said database without loss of said update data; and
verifying, by said data access system, that a query subsequently initiated by said application according to said application schema can be:
received by said data access system;
modified by said data access system utilizing said mapping specification;
performed by said database; and
said update data returned to said application without loss of said update data;
upon validating that said mapping specification permits said update data to losslessly roundtrip between said application and said database, approving subsequent use of said mapping specification by said data access system in providing data services to said application.
2. The method of claim 1 , wherein said mapping specification comprises an expression that relates a query on said application schema to a query on said database schema.
3. The method of claim 1 , wherein said mapping specification comprises an Extensible Markup Language (XML) document.
4. The method of claim 1 , wherein said mapping specification comprises a query on said application schema and a query on said database schema that is equal to said query on said application schema.
5. The method of claim 1 , further comprising determining a set of constraints comprising one or more of a key constraint, an inclusion constraint, a domain constraint, and a disjointness constraint.
6. The method of claim 5 , further comprising utilizing said set of constraints when verifying, by said data access system, that a query initiated by said application according to said application schema can be:
received by said data access system;
modified by said data access system utilizing said mapping specification;
performed by said database; and
requested data returned to said application without loss of said requested data.
7. The method of claim 1 , further comprising translating, by said data access system, a portion of said database schema into a third schema that is equivalent to said portion of a said database schema, and translating a query initiated by said application into a query over said third schema.
8. The method of claim 1 , further comprising determining whether a query view and an update view can be produced from said mapping specification, such that:
said query view expresses at least a portion of said application schema in terms of at least a portion of said database schema;
said update view expresses at least a portion of said database schema in terms of at least a portion of said application schema;
a composition of said query view and said update view produces an identity mapping on said application schema.