Object-Relational Mapping Library

Whether you're targeting .NET Framework, .NET Core, or .NET Standard, XPO will offer the same comprehensive set of capabilities you've come to expect from an ORM Library. And while competing products may claim similar functionality, here are a few features that set eXpress Persistent Objects apart from the competition when it comes to .NET Core & .NET Standard development:

• WCF client support
• Dynamic pooling
• Data caching in high-load systems
• Creating data model structure on the fly, without declaring any .NET classes

XPO for .NET Core / .NET Standard supports the following popular database management systems: SQL Server, MySql, PostreSQL, SQLite, Firebird, Oracle.

Object-Relational Mapping
XPO is an Object-Relational Mapping (ORM) tool that handles all aspects of database creation and object persistence, allowing you to concentrate on your application's business logic. All you need is to define persistent object classes, and XPO will generate the appropriate database structure automatically. By using .NET Reflection and built-in attributes, XPO maps the properties of business objects to relational database tables. Object associations (one-to-one, one-to-many, many-to-many), aggregation and inheritance are all fully supported.

Dynamic Data Model Structure
In addition to .NET Reflection, XPO supports abstract XML-based model for type metadata management. This means that mapping information and custom attributes can be specified and modified dynamically. Such a technique proves indispensable in scenarios when database structure is known only at runtime, so you can define persistent classes structure on the fly.

Data Exchange and Manipulation
Both application-level and database-level transaction types can be manually managed using appropriate Session methods. Unit of Work API encapsulates transactions into functional blocks that can be committed or rolled back altogether. XPO not only provides an interface between the application's code and the database in the form of "insert-select-update-delete" queries to the database, but also enables features such as optimistic concurrency, inheritance mapping and deferred object deletion.

Target a Different Database Engine by Simply Changing the Connection String
XPO supports more than a dozen database management systems and implements a common high-level API. Whether using MS SQL Server, PostgreSQL, MySQL, Oracle, or others, you will use the same code to implement data access and management operations. Should you decide to move your storage to a different database system, you'll only need to change the connection string.

Cloud and Unit Testing Support
You can host data in the cloud, since SQL Azure is fully supported. The data model can be covered with lightweight unit tests because a memory data store can be used instead of a real database.

Distributed Systems
XPO works great with complex distributed applications. You can publish data using Web Services, WCF and Remoting thus shielding direct database connections and reducing the amount of data that travels across the wire. In addition, you can easily create OData services that expose data to any OData-compatible clients like DevExtreme or Xamarin mobile applications.

Reuse Existing Databases with Ease
XPO includes a wizard that reverse-engineers legacy database structures and automatically generates persistent class code. This allows for an easy transition from traditional relational databases to XPO. The generated data model is visualized by the designer and can be further customized.

Stored Procedure Support
The wizard can generate auxiliary helper classes that allow you to directly call existing stored procedures and handle results. Persistent classes and DDL code required to map database views can be auto-generated as well.

Construct the Data Model Using a Visual Designer
Instead of writing code, you can chose to draft the data model within a visual designer: add new objects, specify object relationships, define persistent and calculated properties. The designer displays the entire model in a single window and creates the underlying XPO classes automatically.

Bindable Collections for UI Controls
With XPO, you can retrieve collections of persistent objects and bind them to WinForms, ASP.NET, WPF controls with ease. When Server Mode binding is used, data-aware operations are performed on the data server side and bound controls load data in small portions, on demand. XPO can also load data asynchronously and therefore provide a fast and responsive UI even against very large datasets. After sending a request to a data source, UI control continues responding to user actions while data is being retrieved in a background thread.

Object and Data Layer Caching
Every time a query to the database is made, XPO checks for new versions of the relevant objects in the database and updates the object cache when required. In addition, XPO caches queries and their results as they are being executed on the database server. Whenever a query passes the cache that has been executed previously, the result from that query is returned to the client immediately, without a roundtrip to the server.

Profiling and Diagnostics
XPO Profiler helps you find performance bottlenecks and code issues. Unlike server side SQL query profilers, XPO Profiler runs at the client side and tracks internal XPO events. The profiler provides you with a log of method calls along with passed parameters and corresponding SQL queries side-by-side. This combined log can be much more helpful than just a list of executed queries.

You can specify queries, as well as sorting & filtering criteria, using the following techniques:

• Object-oriented syntax similar to VB.NET and C#
  Free joins, upcasting, and aggregates are all supported.
• Standard LINQ queries against persistent objects using the XPQuery API
  Perform diagnostics by running interactive LINQ queries in LINQPad using the the XPO context driver we've implemented for it.
• Direct SQL queries against a database
  Obtain query results as scalar values, result sets, or object collections.