JCL is a framework for building n-tier, scalable, database agnostic .NET applications. Its core part is the BL (Business Layer) framework that is generated using the LLBLGen code generator.

Each BL class maps to one of the selected tables and/or views in the database. JCL's library DLLs provide support services for these business object classes like security. A JCL's BL class utilizes a database agnostic DAL (Data Access Layer) generated by LLBLGen Pro.

A core concept in the way all data-acces is done in JCL is the use of a Data-Portal. The data-portal provides a single point of reflection that allows the change of the mapping between the application's logical tiers and physical tiers by changing the data-portal settings in the application's configuration file.

This means that although a JCL application is always a logical n-tier application, it can be depolyed on a single physical tier or utilize one or more dedicated application servers to host the BL tier by just changing one line in the application's configuration file (best practices should be considered based on type of targeted interface and scalability requirements).

JCL also provides a WinForms user-interface framework for facilitating the building of data-aware winform applications. The JCL.Windows.Forms framework acts as a first citizen for a JCL BL class and provides base classes for building data-aware screens that facilitate the design and coding of winform classes with a data-source and data-editing functionality that mimics Microsoft Access's Forms.

Because a JCL BL calss does not assume any awarness of the UI, the developer can choose not to use JCL's winforms framework and build web-based or smart-device based applications that utilize a JCL's BL class as its primary data-source.

In addition, web-services can be treated just like any other UI when its necessary to expose one or more JCL BL class through a web-service.