DomainObjects for .NET Features

Type-Safe SQL Statements

Type-safe, IntelliSense^tm supported object queries
Queries are made against persistable objects rather than directly against the database tables. Results are returned as a strongly typed persistable object or list of persistable objects
DataSet or 'report' query support. An arbitrary set of columns can be retrieved from a persistable object and/or its related objects. Results are returned in a DataSet
Design-time declaration and runtime generation of left, right, full outer joins and cross joins
Support for type-safe SQL SELECT expressions: top, union, union all, group by, having, order by, column aliases, etc.
Support for type-safe SQL functions: AVG, CASE, COUNT, DATEDIFF, DATEPART, GETDATE, MAX, SUM, etc.
Support for 'polymorphic' queries: when a base-type is queried, sub-types are also queried and returned.
Support for type-safe batch update statements defined in terms of your object model. See the UpdateByCriteria class for an explanation and a code example.
Support for type-safe batch insert statements defined in terms of your object model. See the InsertByQuery class for an explanation and a code example.

Attribute-based transaction management. I.e., transaction boundaries (units-of-work) and their composition are defined by .NET custom attributes. DomainObjects automatically and transparently handles the database commit/abort. Utilizes semantics of COM+ enterprise services, but without the heavy COM+ infrastructure
Automatic insert, update, delete, retrieval of object graphs per repository collection/reference definitions
Optimistic concurrency support

A call-stack-level cache : when a persistable object is modified, any method executing in that call stack that reads the object will see the modified value(s)
Lazy loading of object references and collections
Connection pooling support
Use of DataReader for optimal performance rather than DataSet or DataTable
Use of SqlParameter cache
Prefetching of related objects in an object graph to prevent database roundtrips. See the Prefetch API for an explanation and code example.
Over 275 automated NUnit regression tests integrated with the DomainObjects build

A tool to automatically reverse-engineer your database schema into an object to relational mapping xml file used by DomainObjects (RepositoryGen.exe)
A persistable object code generator (DomainObjectGen.exe). The code generator creates partial classes from the object-relational mapping file. These partial classes contain the persistent fields along with property accessors and constructors.
Code generation of persistable object fields to be used when creating queries. Enables compile-time feedback and correction of queries as your database schema changes
A set of common persistable object base classes provide functionality needed in a typical persistable object layer:
- Primary key definition and management
- Equals and Hashcode overrides
- Internal state management flags for greater performance and correctness: isEdited, isNew, needsDelete, etc.
- Shallow cloning to properly support optimistic concurrency and transaction isolation in the context of a global object cache
Automatic generation of interfaces from the object-relational mapping file.
Automatic serialization/deserialization of a persistable object graph

Configurable ADO.NET data providers with native support for SQL Server 2000 and 2005 (fully implemented), Oracle 10g and 9i (fully implemented) and MySql (partially implemented)
Automatic primary key sequence management
Support for SQL Server identity columns
Conversion of database types to .NET types and vice-versa at runtime. For example, conversion from a .NET enumeration to a database VARCHAR