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h1. Introduction

The Petals ESB "Embedded Petals Registry Overlay" is a *pre*-extension embedding a default [Petals Registry Overlay|Petals ESB Hazelcast Registry] providing.

This extension was created to simplify the start of a Petals ESB container member of a default standalone topology avoiding to start the Petals registry Overlay as another system process.

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h1. Installation of the extension

This extension is embedded with [the ZIP archive of the Petals ESB container|Installing Petals ESB using the ZIP archive], so no installation is required.

This extension is not available as Debian package because it's dedicated to sample standalone topologies. Debian packages are designed for production installations that are currently based on topologies containing several nodes.

This extension is activated if, in order:
* the topology is a standalone topology (ie. the toplogy contains only one container),
* no registry implementation is configured in the topology,
* the server property {{petals.embedded-registry-overlay}} is not set or set to {{true}}.

h1. Using the Embedded Petals Registry Overlay

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h1. Configuration

h2. Runtime configuration parameters

Configuration parameters of the Embedded Petals Registry Overlay are available into the container local configuration (ie. into the file {{server.properties}}:
|| Parameter/Property name || Default value || Description ||
| {{petals.embedded-registry-overlay}} | {{true}} | Flag enabling/disabling the extension if the topology authorizes to use this extension |

h2. Logging configuration parameters

This extension uses the following logger name to trace its execution: {{Petals.Extensions.EmbeddedRegistryOverlayService}}.

As this extension is provided into the ZIP Archive of Petals ESB, its logging configuration is already configured. If you install this extension through Debian or RPM package, just add something like the following lines to your {{loggers.properties}}:
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Petals.Extensions.EmbeddedRegistryOverlayService.level=FINEST
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