Technology Layers

Every NS application is organized into 6 layers. Each layer encapsulates a distinct responsibility, and each is built using its own set of technologies.

Shared Layer

technologies: Java

Contains common classes used by all layers. Typically simple Java objects used to pass data in a transparent way.

View Layer

technologies: JavaScript, HTML

Contains HTML and JS resources for the user interface.

Control Layer

technologies: Java, Struts2

Contains server side logic for the View Layer. It exposes an HTTP interface.

Proxy Layer

technologies: Java, RMI

Contains Agent classes, which provide a technology-independent interface to access resources in the backend.

Logic Layer

technologies: Java, EJB3

Contains Bean classes, which provide transactions and implementations of tasks and commands.

Data Layer

technologies: Java, JPA

Contains Cruds classes, which provide data access.

The Shared Layer is used by all other layers (except the View Layer) to communicate and pass data between without directly depending on each other.

The View, Control, and Proxy layers together handle getting a request from the user interface to the backend, while the Proxy, Logic, and Data layers handle getting that request from the backend interface down to the database. Splitting responsibilities this way means each layer only needs to know about its direct neighbors, not the whole chain.

Why multiple application instances?

An Application doesn't commit to one technology per layer. That choice is made by its ApplicationInstance, and you can define more than one. This matters whenever your technology needs differ by deployment target or environment: a production deployment might rely on proprietary infrastructure you can't (or don't want to) run on a local development machine, so you'd define one instance for each, sharing the same underlying model.

For the exact class conventions each layer generates, and how they interact between components, see the Layers reference.