h1. New system requirements

Petals ESB needs these following changes at operating system level, see the [compatibility matrix|petalsesb:Compatibility Matrix]:
* a JVM (Java Virtual Machine) implementing Java 17,
* for development purpose:
** Maven 3.9.6+ is needed to build Petals artifacts.

h1. Migrating Petals ESB runtime

To migrate your Petals ESB runtime, just:
* stop all your Petals ESB Hazelcast Registry nodes and your Petals ESB containers,
* migrate your Petals ESB Hazelcast Registry nodes,
* migrate your Petals ESB containers,
* clean your Petals ESB containers,
* restart your Petals ESB Hazelcast Registry nodes,
* restart your Petals ESB containers,
* and, deploy your [migrated Petals ESB topology|#migrating_topology] (shared libraries, components, service assemblies, ...).

h2. Migrating Petals ESB Hazelcast Registry

No migration is required. Just reinstall your ESB Hazelcast Registry with the Petals ESB 5.4.x runtime.

h2. Migrating Petals ESB container

No migration is required. Just reinstall your Petals ESB container with the Petals ESB 5.4.x runtime.

{anchor:migrating_topology}
h1. Migrating your Petals topology

Update your topology to use:
* the new versions of *default* Petals artifacts (shared libraries, components and services assemblies, ...) according to the [compatibility matrix|petalsesb:Compatibility Matrix],
* the [updated versions of *your* Petals artifacts|#migrating_your_artifacts].

{anchor:migrating_your_artifacts}
h1. Migrating your Petals artifacts

h2. Migrating your services

At a runtime level, a large majority of service units running on Petals 5.3.x are compatible with Petals 5.4.x and do not require changes with the exception of:
* [Petals SE Camel service units|petalscomponents:Petals-SE-Camel 1.4.0+#migrationguide],
* [Petals SE POJO service units|petalscomponents:Petals-SE-POJO 2.8.0+#migrationguide].

At a development level, all service units need changes at unit test level because:
* API Jakarta EE 9 is now used by Petals ESB instead of API Java EE,
* and, all Petals component JUnit framework are based on JUnit 5 now:
** [Petals SE Camel service units|petalscomponents:Petals-SE-Camel 1.4.0+#migrationguide],
** [Petals SE Flowable service units|petalsseflowable150:Petals-SE-Flowable 1.5.0+#migrationguide],
** [Petals SE Mapping service units|petalscomponents:Petals SE Mapping 1.3.0+#migrationguide],
** [Petals SE POJO service units|petalscomponents:Petals-SE-POJO 2.8.0+#migrationguide].

*We recommend to migrate all your service units* even if no change is required at runtime level.

h2. Migrating your custom CDK-based components

All your components based on Petals CDK [must be upgraded to the Petals CDK 5.9.x.|petalscomponents:Migration guide#from58xto59x]