Nirmal Fernando created STRATOS-505:
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Summary: Make Stratos Cartridge Agent Truly Extensible
Key: STRATOS-505
URL: https://issues.apache.org/jira/browse/STRATOS-505
Project: Stratos
Issue Type: Improvement
Components: Cartridge Agent
Affects Versions: 4.0.0 Alpha
Reporter: Nirmal Fernando
Assignee: Nirmal Fernando
Priority: Critical
Fix For: 4.0.0 RC1
Current Stratos Cartridge Agent is not truly extensible and it's not that easy
to use it at the moment, with different different Cartridges (Cartridges have
features that are specific to them and it's not correct to expect that every
Cartridge opens up ports etc.).
So, I've come up with following design for the Cartridge Agent.
<please refer to the attached image>
Cartridge Agent's flow is fully customizable now and it is simply a collection
of user defined collection of Phases.
* A Phase corresponds to a period between two life cycle states of the
agent. eg: phase between started state to activated state would be activating
phase.
* A Phase consists of a collection of ExtensionExecutors.
* An ExtensionExecutor can be used to implement different functions that
agent should do within the Phase it belongs to.
* ExtensionExecutor can be a simple Java code, which is capable of
executing script files, checking connections to ports etc.
* ScriptExtensionExecutor is an implementation of the ExtensionExecutor,
which you can use to execute script files using Java's Process.exec command.
* You can write custom Phases by extending
org.apache.stratos.cartridge.agent.phase.Phase abstract class and also you can
write custom ExtensionExecutors by extending
org.apache.stratos.cartridge.agent.executor.ExtensionExecutor abstract class.
How to define the Agent's work-flow?
I've introduced a configuration file to define Agent's work-flow and its
structure is like this;
[<id-of-the-phase>]=<full-qualified-class-name-of-phase>
<full-qualified-class-name-of-extension-executor>
<full-qualified-class-name-of-extension-executor>=<comma-separated-list-of-values>
.....
[<id-of-the-phase>]=<full-qualified-class-name-of-phase>
.....
Path to the file should be set as a system property "agent.flow.file.path".
A sample is given below.
_______________________________________________________________________________________________
[Initializing]=org.apache.stratos.cartridge.agent.phase.impl.InitializingPhase
org.apache.stratos.cartridge.agent.executor.impl.StartListenersExtensionExecutor
org.apache.stratos.cartridge.agent.executor.impl.ScriptExtensionExecutor=instance-started.sh,xxxxxxxxx.sh
[Starting]=org.apache.stratos.cartridge.agent.phase.impl.StartingPhase
org.apache.stratos.cartridge.agent.executor.impl.ScriptExtensionExecutor=start-servers.sh
org.apache.stratos.cartridge.agent.executor.impl.WaitTillActivateExtensionExecutor
org.apache.stratos.cartridge.agent.executor.impl.PersistenceVolumeExtensionExecutor
[WorkingPhase]=org.apache.stratos.cartridge.agent.phase.impl.WorkingPhase
org.apache.stratos.cartridge.agent.executor.impl.LogPublisherExtensionExecutor
org.apache.stratos.cartridge.agent.executor.impl.KeepAgentLiveExtensionExecutor
[CleanUpPhase]=org.apache.stratos.cartridge.agent.phase.impl.CleanUpPhase
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