DevelopTime: Entity Framework Futures

Entity Framework Futures

Tim Mallalieu ’ s “ Entity Framework Futures ” session for the Microsoft Professional Developers

Conference (PDC) 2008 outlined in more detail what developers can expect from EF v2 and other future

Entity Data Model implementations. (You can view the Channel9 video of the presentation at http://

channel9.msdn.com/pdc2008/TL20/ ).

Mallalieu emphasized that data access is the first EDM implementation, but the Entity Data Platform

(EDP) will ultimately manage the following domains:

These scenarios will be supported by four primary EDP technology categories:

Data consumers fall into the following segments, each with their own needs in the preceding domains

and technologies:

· Traditional data developers
· Developers using scripting and “ rebel frameworks, ” such as agile programming
· Model - centric data developers
· Line of business (LOB) script or macro writers
· Information workers

To satisfy agile programmers who insist on plain old CLR objects (POCOs) and total persistence

ignorance, Mallalieu demonstrated writing class code for POCOs and an ObjectContext in the simplest

possible, convention - oriented way. This approach eliminates the EDM and its XML files, and defines an

ObjectSet that implements Iqueryable to deliver completely persistence ignorant code. Adding

mapping attributes enables configuration - oriented code to specify mapping to tables in other schemas or

with column names that don ’ t correspond to property names.

Model - centric developers want to define a model with the EDM Designer and then generate the

database from the model in a manner similar to that employed by LINQ to SQL. EF v2 will add this

capability, which (unfortunately) destroys all data in the database, as well as the capability to define

complex types and implement them by a new “ Artifact Generation Pipeline ” that combines Windows

Workflow and T4 templates. This feature enables developers to modify the workflow, customize the

templates, and build their own design tooling.

Framework developers are independent software vendors (ISVs) who want to build out a data access

layer that leverages the EDM. For example a DBA might create the EDM and the framework developer

would use the *.edmx model to generate POCO classes and enable lazy loading, which was missing from

v1. To prevent the need for direct access to database tables, EF v2 will enable SQL Server table - valued

functions as a data source for composable LINQ to SQL queries, which stored procedures don ’ t support.

New model - defined functions (MDFs) let developers add function definitions, such as FullName() , to

the model. You define MDFs in code, add the SQL expression in the *.edmx file; the expression tree

executes the expression in - line.

Finally, a new feature nicknamed “ Slambda ” lets you use a DbExpression or comprehension syntax to

build a query tree which returns a ADO.NET DbDataReader instead of a typed collection. Beyond v2,

EF and EDM will become a part of the forthcoming Oslo modeling framework with an MEntity domain -

specific grammar. Missing from the presentation was an example of n - tier deployment of EF without the

added overhead of an ADO.NET Data Services (Astoria) layer, as well as support for Contains and

enums, which the DP team won ’ t commit to including in v2.

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