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[[two-hours-intro,Zest™ in 2 hours]]
= Zest™ in 2 hours =

NOTE: This tutorial is not written yet. Learn how to contribute in <<community-docs>>.

This introduction assumes that the "Zest™ in 10 minutes" and "Zest™ in 30 minutes" introductions has been read and
understood.

In this introduction we will touch on the core concepts of UnitOfWork, Application structure and Bootstrap API.

- Persistence and UnitOfWork -

We have previously seen that it is easy to declare that a Composite should be persisted, but not touched on how to
interact with the underlying persistence system. This is done via EntitySessions.

- Application Structure -

    * There are one Application per Zest™ instance.

    * An Application consists of one or more Layers.

    * Each Layer consist of one or more Modules.

    * Layers are organized in a top-down manner, lower Layers on top of higher Layers.

    * One must declare which Composites that each Module is responsible for.

    * A Composite can either be private or public in the Module.

    * A private Composite can only be reached from within the same Module.

    * A public Composite can be reached from other Modules in the same Layer.

    * A public Composite can be declared to be public in the Layer.

    * A Composite that is declared public in the Layer can be reached from the Layers directly on top (not transitive
      to Layers higher up).

    * The Application can also declare public Composites (later for SCA).

For simpler Applications it is possible (quite easily) to create a single Layer with a single Module, but for more
complex Applications we strongly recommend the partitioned approach.

Bootstrap API

-- to be continued