Plugins System Overview

Snooze allows you to use plugins to modify the default behaviour of the application. This page will give you an overview of which components you can plug in Snooze.

General considerations

This section will guide you through the general mechanisms used in Snooze to load its plugins.

Plugins in Snooze are jar files containing classes (one or a set of) compiled outside of the core system and injected at runtime into the system. The plugins have to be located in globals.pluginsDirectory (see Snoozenode Config File). This injection takes place after getting the parameters needed by the plugin from the configuration file (by default snooze_node.cfg).

A plugin contains a main class which derives from an abstract superclass (except for the monitoring estimator, see below). This class must contain a constructor without parameter and a method initialize which is called right after the constructor and is responsible for settings the specific parameter of the plugin.

Below we give a short description of the part which can be used as plugin in Snooze. You can refer to the javadoc (javadoc) to figure out what is available inside your plugin learn from the snooze-plugins project (snooze-plugins).

Virtual Machines and Hosts Monitoring Estimator

• Virtual machine monitoring estimator has to implement VirtualMachineMonitoringEstimator.

This class is responsible for the estimation made on virtual machines resources (CPU, Memory and network).

• HostMonitor monitoring estimator has to implement HostMonitoringEstimator.

This class is responsible for the estimation made on host resources (defined in the configuration file).

Resource Demand Estimator

Resource demand estimator is used for estimate the node resources utilization (Groupmanagers, Localcontroller, Virtualmachines), it is intensively used in placement algorithm (e.g sort the local controller, figure out if a group manager has enough capacity ...).

• A new resource demand estimator has to extend ResourceDemandEstimator.

GroupManager Placement Policy

GroupManager Placement Policy is responsible for placing virtual machines on local controllers.

• A new group manager placement policy has to extend PlacementPolicy.

GroupLeader Dispatching Policy

GroupLeader Dispatching Policy is responsible for dispatching virtual machines on group managers.

• A new group leader dispatching policy has to extend DispatchingPolicy.

GroupLeader Assignement Policy

GroupLeader Assignement Policy is responsible for assignement of local controllers on group managers.

• A new group leader assignement policy has to extend AssignementPolicy.

Anomaly Detector

Anomaly detector is responsible for detecting anomaly on the local controller it runs. In case of detection it sends a message to the group manager.

• A new anomaly detector has to extend AnomalyDetector.

Anomaly Resolver

Anomaly resolver is responsible for resolving an anomaly. Anomaly resolver receives the anomaly message sent by the anomaly local controller.

• A new anomaly resolver has to extend AnomalyResolver.

Local Controller Host Monitor

A host monitor is responsible for getting metrics for the local controller it runs on. You can plug as many monitor you want (be reasonable though).

• A new Host Monitor have to extend HostMonitor.