stella

Interface StatusRequesting

All Superinterfaces:

ErrorDependingParameter, Initializable, Parameter, PropertySupplying

All Known Implementing Classes:

AbstractStatusRequestor, AltTelescope, AzTelescope, FocusPosition, MirrorTemperature, PowerTelescope, TelescopeError

public interface StatusRequesting
extends ErrorDependingParameter

An interface that signals that this parameter obtains its value from an ErrorEvent, normally a status event, sent from the devices and that this value is linked to a changing parameter. An example is the alt/az position of the telescope, which is sent in a TelescopeStatus, but is changing as long as the telescope is moving. To nevertheless get a most accurate value, this parameter directly urges the registered CommandLaunching instance to send a command to its server, which is then followed by an ErrorEvent. This error-event is caught by the parameter serving cluster and piped to this parameter as a response. Now, the value of this parameter is updated and returned. To make this complicated schema a little bit more applicible, mind the following:

• Values are cached. As long as the current time is close enough to the last update time, this cached value is returned.
• If the cached value is considered inaccurate, the command/error-event cycle is launched. This implies that the Parameter.get() method will introduce a certain latency, i.e. it may take some time until it returns.
• For applications that do not need accurate values, the getCache() can be used. This will always return fast.

Field Summary

Fields inherited from interface stella.ErrorDependingParameter

NAMING_EXTENSION

Fields inherited from interface util.PropertySupplying

CONFIG, KEY_CLASS

Method Summary

Modifier and Type	Method and Description
Object	getCache() Returns the cached parameter value.
String	getCacheFormatted() Returns the cache entry as a string, formatted e.g.
boolean	registerLauncher(CommandLaunching launch) Registers a command launching instance to this parameter.

Methods inherited from interface stella.ErrorDependingParameter

getForError, registerError

Methods inherited from interface globals.Parameter

get, getFormatted, getName, getString, set

Methods inherited from interface util.PropertySupplying

defaultBoolean, defaultChar, defaultDouble, defaultFloat, defaultInt, defaultLong, defaultObject, defaultObject, defaultProperties, defaultProperty, getAsBoolean, getAsChar, getAsDouble, getAsFloat, getAsInt, getAsList, getAsLong, getAsMap, getAsObject, getAsObject, getProperties, getProperty, has, parseObject, removeProperty, setObject, setProperty, stringProperties

Methods inherited from interface util.Initializable

init

Method Detail

registerLauncher

boolean registerLauncher(CommandLaunching launch)

Registers a command launching instance to this parameter. It is the responsibility of the parameter to know, if the instance handed over is the right one. Parameter clusters will always pass all of their CommandLaunching instances to its status requesting parameters.

Returns:

True, if this is the coorect command launcher.

getCache

Object getCache()

Returns the cached parameter value. For applications that do not need an accurate value, like visualization tools.

getCacheFormatted

String getCacheFormatted()

Returns the cache entry as a string, formatted e.g. to be displayed in a panel.