h1. Introduction

Several APIs have been introduced in Petals ESB:
* a user API to interact with Petals ESB when it runs. By default, this API is available through the protocol 'JMX'. An extension exists to provide this API through the protocol 'web-service'
* a launching API to launch a Petals ESB container. It's a Java API.
* an internal API to customize or extend Petals ESB. It's a Java API.

* the "Microkernel API" is the API to customize or extend Petals ESB. As a Petals ESB container embeds the server part of the JMX API (see the JBI specifications), the micro-kernel API and the JMX API share some parts through the "Container API".
* the "Launcher API" is an API to write launchers that start Petals ESB container in a dedicated use-case, for example: a production usage, a unit test usage, ... This API and the Petals ESB container share some parts through the "Petals ESB base API".