Translating data and data access operations between applications and databases is a longstanding data management problem. We present a novel approach to this problem, in which the relationship between the application data and the persistent storage is specified using a declarative mapping, which is compiled into bidirectional views that drive the data transformation engine. Expressing the application model as a view on the database is used to answer queries, while viewing the database in terms of the application model allows us to leverage view maintenance algorithms for update translation. This approach has been implemented in a commercial product. It enables developers to interact with a relational database via a conceptual schema and an object-oriented programming surface. We outline the implemented system and focus on the challenges of mapping compilation, which include rewriting queries under constraints and supporting non-relational constructs. Categories and Subject Descriptors:

Traditional client-server applications relegate query and persistence operations on their data to database systems. The database system operates on data in the form of rows and tables, while the application operates on data in terms of higher-level programming language constructs (classes, structures etc.). The impedance mismatch in the data manipulation services between the application and the database tier was problematic even in traditional systems. With the advent of service-oriented architectures (SOA), application servers and multi-tier applications, the need for data access and manipulation services that are well-integrated with programming environments and can operate in any tier has increased tremendously. Microsoft’s ADO.NET Entity Framework is a platform for programming against data that raises the level of abstraction from the relational level to the conceptual (entity) level, and thereby significantly reduces the impedance mismatch for applications and data-centric services. This paper describes the key aspects of the Entity Framework, the overall system architecture, and the underlying technologies. Categories and Subject Descriptors: H.2 [Database Management], D.3 [Programming Languages]

Abstract. The problem of integrating databases and programming languages has been open for nearly 45 years. During this time much progress has been made, in exploring specialized database programming languages, orthogonal persistence, object-oriented databases, transaction models, data access libraries, embedded queries, and object-relational mapping. While new solutions are proposed every year, none has yet proven fully satisfactory. One explanation for this situation is that the problem itself is not sufficiently well defined, so that partial solutions continue to be proposed and evaluated based upon incomplete metrics, making directed progress difficult. This paper is an attempt to clarify the problem, rather than propose a new solution. We review issues that arise on the boundary between programming languages and databases, including typing, optimization, and reuse. We develop specific criteria for evaluating solutions and apply these to the solution approaches mentioned above. The analysis shows that progress has been made, yet the key problem of meeting all the criteria simultaneously remains open. Updated 10/12/2005. So the solution’s easy enough; each of us stays put in his or her corner and takes no notice of the others. You here, you here, and I there. Like soldiers at our posts. Also, we mustn’t speak. Not one word. That won’t be difficult; each of us has plenty of material for self-communings. – Huis Clos (No Exit) by Jean Paul Sartre 1