6.2.8. Configuration Service#
The properties/behaviors of all controlled Subsystems and Components are stored as sets of static properties or metadata in a Configuration Database. Operators or subsystem specialists need to change these properties, so it is not convenient to have them hardcoded. Instead, configuration service manages and modifies the behavior of the subsystems and components. Configurations can be changed as a whole, depending on the operation mode (e.g., different values on limits may be used for testing and calibration than during nominal operation). These properties are loaded during startup, but may be changed individually during the execution of the system (e.g., using a new look-up table to apply error mapping correction in a motion control system).
The GMT SWC is composed of a large number of Subsystems and several thousand Component instances. Some Components are identical, such as the 6 positioners of the seven M2 segments. The behavior of the Controller of each positioner is the same and is implemented as a class, which is a specialization of BaseController. However, the configuration properties of each segment position Controller are different for each instance. As a result, the configuration service has to be able to manage efficiently a large number of configuration properties. As a general rule, there will be at least a default configuration for each component instance. It would be possible to create new configuration snapshots on-the-fly once a property is changed interactively.
Each Subsystem is required to implement a Configuration Adapter, which is a specialization of the BaseConfigurationAdapter. The Configuration Adapter interfaces with the Configuration Service to receive new configuration requests and implements the configuration strategy sequence. The change in configuration Properties of a Component depends on the state of the component, and not all the Properties can be changed in any state. For example, servo gain cannot be changed when a Controller is performing a motion in normal operation mode or the readout gain of a detector cannot be changed in the middle of a readout operation.
The SWCS requirements on Configuration Services are shown in the following Table:
Requirement |
Statement |
|---|---|
SWC Observing Mode Switching |
Provide the capability to switch from one observing mode to another. |
SWC Telescope Optical Configuration Switching |
Provide capability to switch from one telescope optical configuration to another in an automatic way for any active instruments. |
SWC Automated Instrument Switching |
Provide capability to automate the switching of the active instrument set during the night initiated and monitored by the operator. |
Software Component Configuration Parameters |
Provide the capability to associate a set of configuration parameters with any software component. |
Service Features and Properties
The Configuration Service provides the ability to store properties, to group them into sets called configurations, to view the current properties used by a Subsystem, and to consult the available configuration for a Subsystem (e.g., default configuration, calibration configuration).
At least one predefined configuration for each GMT subsystem must exist, named the default. This configuration is loaded when a subsystem starts and enters the state setup (The Section on Controller State Machine explains the different states of a component). Although the Configuration Service checks to see if the value of a property is the correct range, it is the responsibility of the Subsystem or Component to check the correctness and consistency with predefined configurations before is applied. Individual property changes are allowed, but can only be saved as part of an existing or new configuration if the user has the appropriate permission. Configuration and Property changes are always logged to facilitate debugging in case of a malfunction.
Properties that represent physical magnitudes must specify their units and the data type. Only units defined as UnitType, and data types defined as DataTypes in the metamodel can be used in the definition of a property metadata.
Service Packages
Service Package -
A configuration server system, deployed in several machines, takes care of receiving configuration request and updates, storing or sending them to components that made the requests.
In addition to handling configuration properties, the configuration server provides features that allow the management of load balancing and fault tolerance. The configuration service operation, as any other component can be monitored by the telemetry system by specifying monitoring
Visualization Package -
The visualization package provides custom panels that allow observatory operators to monitor and manage the configuration service, shown in the following table:
Table 6.12 Configuration Service Visualization Panels# Visualization Panel
Description
Global Panel
Provides an overall view of the status of the configuration service. The following information will be displayed:
State of each server component (e.g., RUNNING, STOPPED, FAULT)
State of each adapter component (e.g., RUNNING, STOPPED, FAULT)
Overall view of the system health, one box per subsystem color coded: - green: No active alarms - yellow: No serious active alarms - red: Critical alarm active
Navigation Panel
Provides a way to navigate all the configuration servers and adapters. From the navigation panel the state and detailed info of every server and adapter can be accessed. The Navigation Panel allows also browsing efficiently all configurations of the GMT software components.
Guide Panel
Displays the on line documentation of the configuration service. Allows access to the user guide as well as the metadata (model information) of the runtime objects.
Analytics Panel
Provides access to the runtime statistics of the configuration service. These should include at least.
Number and state (running/stopped/fault)
Instant throughput of the system
Configuration changes/sec
Total data bandwidth
Storage capacity (used/available)
Service Editor Panel
The Configuration Editor Panel provides the capability to edit the values of the properties of a configuration. It also enables to save, copy, or delete the configuration of any given component.
Service Deployment
The Configuration Supervisor is deployed in one of the SCC in the electronic room. The Supervisor has access to a permanent store and is available to all runtime components through the service bus.