Type Parameters:

T - the type of the Channel. One out of OpenemsType.

All Known Subinterfaces:

WriteChannel<T>

All Known Implementing Classes:

AbstractReadChannel, BooleanReadChannel, BooleanWriteChannel, DoubleReadChannel, DoubleWriteChannel, EnumReadChannel, EnumWriteChannel, FloatReadChannel, FloatWriteChannel, IntegerReadChannel, IntegerWriteChannel, LongReadChannel, LongWriteChannel, ShortReadChannel, ShortWriteChannel, StateChannel, StateCollectorChannel, StringReadChannel, StringWriteChannel
```
public interface Channel<T>
```
An OpenEMS Channel holds one specific piece of information of an OpenemsComponent.
A Channel has
- a Channel-ID which is unique among the OpenemsComponent. (see ChannelId)
- a Doc as static meta information. (via channelDoc())
- a system-wide unique ChannelAddress built from Component-ID and Channel-ID. (via address()
- a OpenemsType which needs to map to the generic parameter <T>. (via getType())
- an (active) Value. (via value())
- callback methods to listen on value updates and changes. (see Channel#onChange(Consumer), onUpdate(Consumer) and onSetNextValue(Consumer))
Channels implement a 'Process Image' pattern. They provide an 'active' value which should be used for any operations on the channel value. The 'next' value is filled by asynchronous workers in the background. At the 'Process Image Switch' the 'next' value is copied to the 'current' value.
The recommended implementation of an OpenEMS Channel is via AbstractReadChannel.

Field Summary

Fields
Modifier and Type Field Description

static int NO_OF_PAST_VALUES
Holds the number of past values for this Channel that are kept in the 'pastValues' variable.

Method Summary

All Methods Instance Methods Abstract Methods Default Methods Deprecated Methods
Modifier and Type	Method	Description
`void`	`_setNextValue(T value)`	Deprecated.
`ChannelAddress`	`address()`	Gets the address of this Channel.
`default Doc`	`channelDoc()`	Gets the ChannelDoc of this Channel.
`ChannelId`	`channelId()`	Gets the ChannelId of this Channel.
`void`	`deactivate()`	Deactivates the Channel and makes sure all callbacks are released for garbe collection to avoid memory-leaks.
`OpenemsComponent`	`getComponent()`	Gets the OpenemsComponent this Channel belongs to.
`Value<T>`	`getNextValue()`	Gets the 'next value'.
`CircularTreeMap<java.time.LocalDateTime,Value<T>>`	`getPastValues()`	Gets the past values for this Channel.
`OpenemsType`	`getType()`	Gets the type of this Channel, e.g.
`void`	`nextProcessImage()`	Switches to the next process image, i.e.
`java.util.function.BiConsumer<Value<T>,Value<T>>`	`onChange(java.util.function.BiConsumer<Value<T>,Value<T>> callback)`	Add an onChange callback.
`java.util.function.Consumer<Value<T>>`	`onSetNextValue(java.util.function.Consumer<Value<T>> callback)`	Add an onSetNextValue callback.
`java.util.function.Consumer<Value<T>>`	`onUpdate(java.util.function.Consumer<Value<T>> callback)`	Add an onUpdate callback.
`void`	`removeOnChangeCallback(java.util.function.BiConsumer<?,?> callback)`	Removes an onChange callback.
`void`	`removeOnSetNextValueCallback(java.util.function.Consumer<?> callback)`	Removes an onSetNextValue callback.
`void`	`removeOnUpdateCallback(java.util.function.Consumer<Value<?>> callback)`	Removes an onUpdate callback.
`default void`	`setNextValue(java.lang.Object value)`	Updates the 'next value' of Channel.
`Value<T>`	`value()`	Gets the currently active value, wrapped in a @{link Value}.

- Field Detail
  - NO_OF_PAST_VALUES
```
static final int NO_OF_PAST_VALUES
```
    Holds the number of past values for this Channel that are kept in the 'pastValues' variable.
    
    See Also:
    
    Constant Field Values
- Method Detail
  - channelId
```
ChannelId channelId()
```
    Gets the ChannelId of this Channel.
    
    Returns:
  - channelDoc
```
default Doc channelDoc()
```
    Gets the ChannelDoc of this Channel.
    
    Returns:
  - getComponent
```
OpenemsComponent getComponent()
```
    Gets the OpenemsComponent this Channel belongs to.
    
    Returns:
  - address
```
ChannelAddress address()
```
    Gets the address of this Channel.
    
    Returns:
  - nextProcessImage
```
void nextProcessImage()
```
    Switches to the next process image, i.e. copies the "next"-value into "current"-value.
  - getType
```
OpenemsType getType()
```
    Gets the type of this Channel, e.g. INTEGER, BOOLEAN,..
    
    Returns:
  - setNextValue
```
default void setNextValue(java.lang.Object value)
```
    Updates the 'next value' of Channel.
    
    Parameters:
    
    value - the 'next value'. It is going to be the 'value' after the next ProcessImage gets activated.
  - getNextValue
```
Value<T> getNextValue()
```
    Gets the 'next value'.
    Note that usually you should prefer the value() method.
    
    Returns:
    
    the 'next value'
  - onSetNextValue
```
java.util.function.Consumer<Value<T>> onSetNextValue(java.util.function.Consumer<Value<T>> callback)
```
    Add an onSetNextValue callback. It is called, after a new NextValue was set. Note that usually you should prefer the onUpdate() callback.
    Remember to remove the callback using removeOnSetNextValueCallback(Consumer) once it is not needed anymore, e.g. on deactivate().
    
    Parameters:
    
    callback - the callback Consumer
    
    Returns:
    
    the callback to enable fluent programming
    
    See Also:
    
    onUpdate(java.util.function.Consumer<io.openems.edge.common.channel.value.Value<T>>)
  - removeOnSetNextValueCallback
```
void removeOnSetNextValueCallback(java.util.function.Consumer<?> callback)
```
    Removes an onSetNextValue callback.
    
    Parameters:
    
    callback - the callback Consumer
    
    See Also:
    
    onSetNextValue(Consumer)
  - _setNextValue
```
@Deprecated
void _setNextValue(T value)
```
    Deprecated.
    
    Internal method. Do not call directly.
    
    Parameters:
    
    value - the 'next value'
  - value
```
Value<T> value()
        throws java.lang.IllegalArgumentException
```
    Gets the currently active value, wrapped in a @{link Value}.
    
    Throws:
    
    java.lang.IllegalArgumentException - if value cannot be access, e.g. because the Channel is Write-Only.
  - getPastValues
```
CircularTreeMap<java.time.LocalDateTime,Value<T>> getPastValues()
```
    Gets the past values for this Channel.
    
    Returns:
    
    a map of recording time and historic value at that time
  - onUpdate
```
java.util.function.Consumer<Value<T>> onUpdate(java.util.function.Consumer<Value<T>> callback)
```
    Add an onUpdate callback. It is called, after the active value was updated by nextProcessImage().
  - removeOnUpdateCallback
```
void removeOnUpdateCallback(java.util.function.Consumer<Value<?>> callback)
```
    Removes an onUpdate callback.
    
    Parameters:
    
    callback - the callback Consumer
    
    See Also:
    
    onUpdate(Consumer)
  - onChange
```
java.util.function.BiConsumer<Value<T>,Value<T>> onChange(java.util.function.BiConsumer<Value<T>,Value<T>> callback)
```
    Add an onChange callback. It is called, after a new, different active value was set by nextProcessImage().
    
    Parameters:
    
    callback - old value and new value
  - removeOnChangeCallback
```
void removeOnChangeCallback(java.util.function.BiConsumer<?,?> callback)
```
    Removes an onChange callback.
    
    Parameters:
    
    callback - the callback BiConsumer
    
    See Also:
    
    onChange(BiConsumer)
  - deactivate
```
void deactivate()
```
    Deactivates the Channel and makes sure all callbacks are released for garbe collection to avoid memory-leaks.

Interface Channel<T>

Field Summary

Method Summary

Field Detail

NO_OF_PAST_VALUES

Method Detail

channelId

channelDoc

getComponent

address

nextProcessImage

getType

setNextValue

getNextValue

onSetNextValue

removeOnSetNextValueCallback

_setNextValue

value

getPastValues

onUpdate

removeOnUpdateCallback

onChange

removeOnChangeCallback

deactivate