v4 Documentation Preview

# Binding Definitions

In order to work with Things and Channels, some meta information about them is needed.

These are provided through 'ThingType' and 'ChannelType' definitions, which describe details about their functionality and configuration options.

# ThingTypeProvider / ChannelTypeProvider

Technically, the thing types are provided by ThingTypeProviders (org.openhab.core.thing.binding.ThingTypeProvider).

openHAB comes with an implementation of such a provider that reads XML files from the folder OH-INF/thing of bundles. Although we refer to this XML syntax in the following, you also have the option to provide directly object model instances through your own provider implementation.

The same applies for the channel types. The ChannelTypeProvider interface can be registered as OSGi service to provide channel types programmatically. When implementing a dynamic ThingTypeProvider you can also refer to the channel types that are defined inside XML files.

# Things

Things represent devices or services that can be individually added to, configured or removed from the system. They either contain a set of channels or a set of channel groups. A bridge is a specific type of thing as it can additionally provide access to other Things as well. Which Things can be associated through which bridge type is defined within the description of a thing:

    <thing-type id="thingTypeID">
        <supported-bridge-type-refs>
            <bridge-type-ref id="bridgeTypeID" />
        </supported-bridge-type-refs>
        <label>Sample Thing</label>
        <description>Some sample description</description>
        <category>Lightbulb</category>
    ...
    </thing-type>

Bindings may optionally set the listing of a thing type. By doing do, they indicate to user interfaces whether it should be shown to the users or not, e.g. when pairing things manually:

    <thing-type id="thingTypeID" listed="false">
        ...
    </thing-type>

Thing types are listed by default, unless specified otherwise. Hiding thing types potentially makes sense if they are deprecated and should not be used anymore. Also, this can be useful if users should not be bothered with distinguishing similar devices which for technical reasons have to have separate thing types. In that way, a generic thing type could be listed for users and a corresponding thing handler would change the thing type immediately to a more concrete one, handing over control to the correct specialized handler.

# Thing Categories

Categories are used to provide meta information about Things. Thing categories describe how the physical device looks like. UIs can use this information e.g. to render icons. The available categories correspond with the available icons of the classic iconset, however categories are written in Java class-naming style, e.g. FrontDoor instead of lowercase frontdoor.

# Channels

A channel describes a specific functionality of a thing and can be linked to an item. So the basic information is, which command types the channel can handle and which state it sends to the linked item. This can be specified by the accepted item type. Inside the thing type description XML file a list of channels can be referenced. The channel type definition is specified on the same level as the thing type definition. That way channels can be reused in different things.

The granularity of channel types should be on its semantic level, i.e. very fine-grained: If a Thing measures two temperature values, one for indoor and one for outdoor, this should be modelled as two different channel types. Overriding labels of a channel type must only be done if the very same functionality is offered multiple times, e.g. having an actuator with 5 relays, which each is a simple "switch", but you want to individually name the channels (1-5).

# State Channel Types

The following XML snippet shows a thing type definition with 2 channels and one referenced channel type:

<thing-type id="thingTypeID">
    <label>Sample Thing</label>
    <description>Some sample description</description>
    <channels>
        <channel id="switch" typeId="powerSwitch" />
        <channel id="temperature" typeId="setpointTemperature" />
    </channels>
</thing-type>
<channel-type id="setpointTemperature" advanced="true">
    <item-type>Number</item-type>
    <label>Setpoint Temperature</label>
    <category>Temperature</category>
    <state min="12" max="30" step="0.5" pattern="%.1f °C" readOnly="false" />
</channel-type>

In order to reuse identical channels in different bindings a channel type can be system-wide. A channel type can be declared as system-wide by setting its system property to true and can then be referenced using a system. prefix in a channel typeId attribute in any binding - note that this should only be done in the core framework, but not by individual bindings!

The following XML snippet shows a system channel type definition and thing type definition that references it:

<thing-type id="thingTypeID">
    <label>Sample Thing</label>
    <description>Some sample description</description>
    <channels>
        <channel id="s" typeId="system.system-channel" />
    </channels>
</thing-type>
<channel-type id="system-channel" system="true">
    <item-type>Number</item-type>
    <label>System Channel</label>
    <category>QualityOfService</category>
</channel-type>

# System State Channel Types

There exist system-wide channel types that are available by default and which should be used whenever possible:

Channel Type ID Reference typeId Item Type Category Tags Description
signal-strength system.signal-strength Number QualityOfService Measurement, Level Represents signal strength of a device as a Number with values 0, 1, 2, 3 or 4; 0 being worst strength and 4 being best strength.
low-battery system.low-battery Switch LowBattery LowBattery, Energy Represents a low battery warning with possible values on (low battery) and off (battery ok).
battery-level system.battery-level Number Battery Measurement, Energy Represents the battery level as a percentage (0-100%). Bindings for things supporting battery level in a different format (e.g. 4 levels) should convert to a percentage to provide a consistent battery level reading.
power system.power Switch Switch Switch, Power Turn a device on/off.
brightness system.brightness Dimmer Light Control, Light Brightness of a bulb (0-100%).
color system.color Color ColorLight Control, Light Color of a bulb.
color-temperature system.color-temperature Dimmer ColorLight Control, ColorTemperature Color temperature of a bulb (0-100%). 0% should be the coldest setting (highest Kelvin value), 100 the warmest.
color-temperature-abs system.color-temperature-abs Number ColorLight Control, ColorTemperature Color temperature of a bulb in Kelvin (1000K-10000K).
location system.location Location - Measurement Location in lat.,lon.,height coordinates.
motion system.motion Switch Motion Status, Presence Motion detected by the device (ON if motion is detected).
mute system.mute Switch SoundVolume Switch, SoundVolume Turn on/off the volume of a device.
volume system.volume Dimmer SoundVolume Control, SoundVolume Change the sound volume of a device (0-100%).
media-control system.media-control Player MediaControl Control Control for a media player.
media-title system.media-title String - Status Title of a (played) media file.
media-artist system.media-artist String - Status Artist of a (played) media file.
outdoor-temperature system.outdoor-temperature Number:Temperature Temperature Measurement, Temperature Current outdoor temperature.
indoor-temperature system.indoor-temperature Number:Temperature Temperature Measurement, Temperature Current indoor temperature.
wind-direction system.wind-direction Number:Angle Wind Measurement, Wind Wind direction in degrees (0-360°).
wind-speed system.wind-speed Number:Speed Wind Measurement, Wind Wind speed
atmospheric-humidity system.atmospheric-humidity Number:Dimensionless Humidity Measurement, Humidity Atmospheric humidity in percent.
barometric-pressure system.barometric-pressure Number:Pressure Pressure Measurement, Pressure Barometric pressure
electric-current system.electric-current Number:ElectricCurrent Energy Measurement, Current Electric current
electric-power system.electric-power Number:Power Energy Measurement, Power Electric power
electric-voltage system.electric-voltage Number:ElectricPotential Energy Measurement, Voltage Electric voltage
electrical-energy system.electric-energy Number:Energy Energy Measurement, Energy Electrical energy

The advanced property indicates whether this channel is a basic or a more specific functionality of the thing. If advanced is set to true a user interface may hide this channel by default. The default value is false and thus will be taken if the advanced attribute is not specified. Especially for complex devices with a lot of channels, only a small set of channels - the most important ones - should be shown to the user to reduce complexity. Whether a channel should be declared as advanced depends on the device and can be decided by the binding developer. If a functionality is rarely used it should be better marked as advanced.

# Trigger Channel Types

The following XML snippet shows a trigger channel:

<thing-type id="thingTypeID">
    <label>Sample Thing</label>
    <description>Some sample description</description>
    <channels>
        <channel id="s" typeId="trigger-channel" />
    </channels>
</thing-type>
<channel-type id="trigger-channel">
    <kind>trigger</kind>
    <label>Trigger Channel</label>
    <event>
        <options>
            <option value="PRESSED">pressed</option>
            <option value="RELEASED">released</option>
            <option value="DOUBLE_PRESSED">double pressed</option>
        </options>
    </event>
</channel-type>

This channel can emit the event payloads PRESSED, RELEASED and DOUBLE_PRESSED.

If no <event> tag is specified, the channel can be triggered, but has no event payload. If an empty <event> tag is specified, the channel can trigger any event payload.

# System Trigger Channel Types

There exist system-wide trigger channel types that are available by default:

Channel Type ID Reference typeId Description
trigger system.trigger Can only trigger, no event payload
rawbutton system.rawbutton Can trigger PRESSED and RELEASED
button system.button Can trigger SHORT_PRESSED, DOUBLE_PRESSED and LONG_PRESSED
rawrocker system.rawrocker Can trigger DIR1_PRESSED, DIR1_RELEASED, DIR2_PRESSED and DIR2_RELEASED

In the following sections the declaration and semantics of tags, state descriptions and channel categories will be explained in more detail. For a complete sample of the thing types XML file and a full list of possible configuration options please see the XML Configuration Guide.

# Default Tags

The XML definition of a ChannelType allows to assign default tags to channels. All items bound to this channel will automatically be tagged with these default tags. The following snippet shows a 'Control' and 'Light' tags definition:

<tags>
    <tag>Control</tag>
    <tag>Light</tag>
</tags>

Please note that only Point (opens new window) and/or Property (opens new window) tags from the pre-defined tag library should be used. See also the Semantic Model for more information on how tags are used with items.

# State Description

The state description allows to specify restrictions and additional information for the state of an item, that is linked to the channel. Some configuration options are only valid for specific item types. The following XML snippet shows the definition for a temperature actuator channel:

<state min="12" max="30" step="0.5" pattern="%.1f %unit%" readOnly="false"></state>
  • The attributes min and max can only be declared for channel with the item type Number. It defines the range of the numeric value. The Java data type is a BigDecimal. For example user interfaces can create sliders with an appropriate scale based on this information.
  • The step attribute can be declared for Number and Dimmer items and defines what is the minimal step size that can be used.
  • The readonly attribute can be used for all item types and defines if the state of an item can be changed. For all sensors the readonly attribute should be set to true.
  • The pattern attribute can be used for Number and String items. It gives user interface a hint how to render the item. The format of the pattern must be compliant to the Java Number Format (opens new window). The pattern can be localized (see also Internationalization). The special pattern placeholder %unit% is used for channels which bind to items of type Number:<dimension> which define a dimension for unit support. These channels will send state updates of type QuantityType and the unit is then rendered for the placeholder.

Some channels might have only a limited and countable set of states. These states can be specified as options. A String or Number item must be used as item type. In general String should be preferred with a meaningful option value. This prevents the user from having to guess what a value represents if a number is used as option value. Number is useful when the value represents a quantity (e.g. like in the system-wide channel type signal-strength).

The following XML snippet defines a list of predefined state options:

<state readOnly="true">
    <options>
        <option value="HIGH">High Pressure</option>
        <option value="MEDIUM">Medium Pressure</option>
        <option value="LOW">Low Pressure</option>
    </options>
</state>

The user interface can use these values to render labels for values or to provide a selection of states, when the channel is writable. The option labels can also be localized.

# Command Description

If the primary purpose of a channel is to send commands towards a device (i.e. the opposite direction of trigger channels), it can use command options.

A String item must be used as item type.

The following XML snippet defines a list of commands:

<command>
    <options>
        <option value="ALARM">Alarm</option>
        <option value="LSELECT">Long Alarm</option>
    </options>
</command>

The user interface can use these values to render

  • a drop down and also represent the current state or
  • as push buttons to simply send a command to the ThingHandler.

The option labels can also be localized.

# Dynamic State / Command Description

In situations where the static definition of a state description is not sufficient a binding would implement a DynamicStateDescriptionProvider or a DynamicCommandDescriptionProvider.

These providers allow to provide a StateDescription (or CommandDescription respectively) based on the specific Channel.

Also implement this interface if you want to provide dynamic state / command options. The original StateDescription/CommandDescription is available for modification and enhancement. The framework provides two abstract implementations for bindings to support translation, publishing ChannelDescriptionChangedEvents and other basic features: BaseDynamicStateDescriptionProvider and BaseDynamicCommandDescriptionProvider.

The StateDescriptionFragmentBuilder (and CommandDescriptionBuilder) can be used to only provide the information which is available at the time of construction.

# Example code for a DynamicStateDescriptionProvider implementation
@Component(service = { DynamicStateDescriptionProvider.class, ExampleDynamicStateDescriptionProvider.class })
public class ExampleDynamicStateDescriptionProvider implements DynamicStateDescriptionProvider {

    private final Map<ChannelUID, @Nullable List<StateOption>> channelOptionsMap = new ConcurrentHashMap<>();

    /**
     * For a given channel UID, set a {@link List} of {@link StateOption}s that should be used for the channel, instead
     * of the one defined statically in the {@link ChannelType}.
     *
     * @param channelUID the channel UID of the channel
     * @param options a {@link List} of {@link StateOption}s
     */
    public void setStateOptions(ChannelUID channelUID, List<StateOption> options) {
        channelOptionsMap.put(channelUID, options);
    }

    @Override
    public @Nullable StateDescription getStateDescription(Channel channel, @Nullable StateDescription original,
            @Nullable Locale locale) {
        List<StateOption> options = channelOptionsMap.get(channel.getUID());
        if (options == null) {
            return null;
        }

        StateDescriptionFragmentBuilder builder = (original == null) ? StateDescriptionFragmentBuilder.create()
                : StateDescriptionFragmentBuilder.create(original);
        return builder.withOptions(options).build().toStateDescription();
    }

    @Deactivate
    public void deactivate() {
        channelOptionsMap.clear();
    }
}
# Example code for a DynamicStateDescriptionProvider implementation which extends the BaseDynamicStateDescriptionProvider
@Component(service = { DynamicStateDescriptionProvider.class, ExampleDynamicStateDescriptionProvider.class })
public class ExampleDynamicStateDescriptionProvider extends BaseDynamicStateDescriptionProvider {

    @Activate
    public ExampleDynamicStateDescriptionProvider(final @Reference EventPublisher eventPublisher, //
            final @Reference ItemChannelLinkRegistry itemChannelLinkRegistry, //
            final @Reference ChannelTypeI18nLocalizationService channelTypeI18nLocalizationService) {
        this.eventPublisher = eventPublisher;
        this.itemChannelLinkRegistry = itemChannelLinkRegistry;
        this.channelTypeI18nLocalizationService = channelTypeI18nLocalizationService;
    }
}
# Example code for a DynamicCommandDescriptionProvider implementation
@Component(service = { DynamicCommandDescriptionProvider.class, ExampleDynamicCommandDescriptionProvider.class })
public class ExampleDynamicCommandDescriptionProvider implements DynamicCommandDescriptionProvider {

    private final Map<ChannelUID, @Nullable List<CommandOption>> channelOptionsMap = new ConcurrentHashMap<>();

    /**
     * For a given channel UID, set a {@link List} of {@link CommandOption}s that should be used for the channel,
     * instead of the one defined statically in the {@link ChannelType}.
     *
     * @param channelUID the channel UID of the channel
     * @param options a {@link List} of {@link CommandOption}s
     */
    public void setCommandOptions(ChannelUID channelUID, List<CommandOption> options) {
        channelOptionsMap.put(channelUID, options);
    }

    @Override
    public @Nullable CommandDescription getCommandDescription(Channel channel,
            @Nullable CommandDescription originalCommandDescription, @Nullable Locale locale) {
        List<CommandOption> options = channelOptionsMap.get(channel.getUID());
        if (options == null) {
            return null;
        }

        return CommandDescriptionBuilder.create().withCommandOptions(options).build();
    }
}

Most of the times handlers need to modify those dynamic information. Therefore the ThingHandlerFactory has to reference the bundle instance and pass it to the handler.

public class ExampleHandlerFactory extends BaseThingHandlerFactory {

    private final ExampleDynamicStateDescriptionProvider stateDescriptionProvider;

    @Activate
    public ExampleHandlerFactory(final @Reference ExampleDynamicStateDescriptionProvider stateDescriptionProvider) {
        this.stateDescriptionProvider = stateDescriptionProvider;
    }

    @Override
    protected ThingHandler createHandler(Thing thing) {
        if (EXAMPLE_THING_TYPE.equals(thing.getThingTypeUID())) {
            return new ExampleHandler(thing, stateDescriptionProvider);
        }
        return null;
    }
}

# Channel Categories

Channel categories are used to provide meta information about channels. Channel categories describe the functional purpose of the channel and are used by the UI to render icons. The available categories correspond with the available icons of the classic iconset, however categories are written in Java class-naming style, e.g. BatteryLevel instead of lowercase batterylevel.

# Channel Groups

Some devices might have a lot of channels. There are also complex devices like a multi-channel actuator, which is installed inside the switchboard, but controls switches in other rooms. Therefore channel groups can be used to group a set of channels together into one logical block. A thing can only have direct channels or channel groups, but not both.

Inside the thing types XML file channel groups can be defined like this:

<thing-type id="multiChannelSwitchActor">
    <!-- ... -->
    <channel-groups>
        <channel-group id="switchActor1" typeId="switchActor" />
        <channel-group id="switchActor2" typeId="switchActor" />
    </channel-groups>
    <!-- ... -->
</thing-type>

The channel group type is defined on the same level as the thing types and channel types. The group type must have a label, an optional description, and an optional category (e.g. used to render an icon).. Moreover the list of contained channels must be specified:

<channel-group-type id="switchActor">
    <label>Switch Actor</label>
    <description>This is a single switch actor with a switch channel</description>
    <category>Light</category>
    <channels>
        <channel id="switch" typeId="switch" />
    </channels>
</channel-group-type>

When a thing will be created for a thing type with channel groups, the channel UID will contain the group ID in the last segment divided by a hash (#). If an Item should be linked to a channel within a group, the channel UID would be binding:multiChannelSwitchActor:myDevice:switchActor1#switch for the XML example before.

# Properties

Solutions based on openHAB might require meta data from a device. These meta data could include:

  • general device information, e.g. the device vendor, the device series or the model ID, ...
  • device characteristics, e.g. if it is battery based, which home automation protocol is used, what is the current firmware version or the serial number, ...
  • physical descriptions, e.g. what is the size, the weight or the color of the device, ...
  • any other meta data that should be made available for the solution by the binding

Depending on the solution the provided meta data can be used for different purposes. Among others the one solution could use the data during a device pairing process whereas another solution might use the data to group the devices/things by the vendors or by the home automation protocols on a user interface. To define such thing meta data the thing type definition provides the possibility to specify so-called properties:

    <thing-type id="thingTypeId">
        ...
        <properties>
             <property name="vendor">MyThingVendor</property>
             <property name="modelId">thingTypeId</property>
             <property name="protocol">ZigBee</property>
             ...
        </properties>
    ...
    </thing-type>

In general each property must have a name attribute which should be written in camel case syntax. The actual property value is defined as plain text and is placed as child node of the property element. It is recommended that at least the vendor and the model id properties are specified here since they should be definable for the most of the devices. In contrast to the properties defined in the 'ThingType' definitions the thing handler documentation explains how properties can be set during runtime.

# Representation Property

A thing type can contain a so-called representation property. This optional property contains the name of a property whose value can be used to uniquely identify a device. The thingUID cannot be used for this purpose because there can be more than one thing for the same device.

Each physical device normally has some kind of a technical identifier which is unique. This could be a MAC address (e.g. Hue bridge, camera, all IP-based devices), a unique device id (e.g. a Hue lamp) or some other property that is unique per device type. This property is normally part of a discovery result for that specific thing type. Having this property identified per binding it could be used as the representation property for this thing.

The representation property shall be defined in the thing type XML:

    <thing-type id="thingTypeId">
        ...
        <properties>
            <property name="vendor">Philips</property>
        </properties>
        <representation-property>uniqueId</representation-property>
        ...
    </thing-type>

Note that the representation property is normally not listed in the properties part of the Thing type XML, as this part contains static properties, that are the same for all instances of this Thing type. The name of the representation property identifies a property or configuration parameter that is added to the Thing in the Thing handler upon successful initialization.

# Representation Property and Discovery

The representation property is used to auto-ignore discovery results of Things that already exist in the system. This can happen if, a) a Thing has been created manually, or b) the Thing has been discovered separately by two mechanisms e.g. by mDNS, and by NetBios, or UPnP. If this is the case, the Thing in the inbox is automatically ignored. Note that this Thing is automatically removed when the manually added Thing is removed. A new discovery would then automatically find this Thing again and add it to the inbox properly.

See also Implementing a Discovery Service

When comparing representation properties, the auto-ignore service checks for matches between the representation property of the newly discovered Thing, and both the properties and the configuration parameters of existing Things. If a configuration parameter will be used, then its respective parameter shall be declared in the XML config-description section or the config-description XML file:

    <thing-type id="thingTypeId">
        ...
        <representation-property>uniqueId</representation-property>
        ...
        <config-description>
          <parameter name="uniqueId" type="text">
            <label>Unique Id</label>
            <description>The Unique Id for Representation Property</description>
          </parameter>
        </config-description>
        ...
    </thing-type>

# Formatting Labels and Descriptions

The label and descriptions for things, channels and config descriptions should follow the following format. The label should be short so that for most UIs it does not spread across multiple lines. Guideline is 2-3 words with up to 25 chars. Labels should be capitalized using the following rules:

  • Always capitalize the first and the last word.
  • Lowercase articles, coordinating conjunctions, and prepositions (a, an, the, and, as, but, by, for, from, in, into, like, near, nor, of, onto, or, out, over, past, so, till, to, up, upon, with, yet).
  • Capitalize all other words.
  • Brand- or product names that starts with a lowercase character can be written using their official spelling.

The description can contain longer text to describe the thing in more detail. Limited use of HTML tags is permitted to enhance the description - if a long description is provided, the first line should be kept short, and a line break (<br />) placed at the end of the line to allow UIs to display a short description in limited space.

Configuration options should be kept short so that they are displayable in a single line in most UIs. If you want to provide a longer description of the options provided by a particular parameter, then this should be placed into the <description> of the parameter to keep the option label short. The description can include limited HTML to enhance the display of this information.

The following HTML tags are allowed : <b>, <br />, <em>, <h1>, <h2>, <h3>, <h4>, <h5>, <h6>, <i>, <p>, <small>, <strong>, <sub>, <sup>, <ul>, <ol>, <li>. These must be inside the XML escape sequence - e.g. <description><![CDATA[ HTML marked up text here ]]></description>.

# Auto Update Policies

Channel types can optionally define a policy with respect to the auto update handling. This influences the decision within the framework if an auto-update of the item's state should be sent in case a command is received for it. The auto update policy typically is inherited by the channel from its channel type. Nevertheless, this value can be overridden in the channel definition.

In this example, an auto update policy is defined for the channel type, but is overridden in the channel definition:

<channel-type id="channel">
    <label>Channel with an auto update policy</label>
    <autoUpdatePolicy>recommend</autoUpdatePolicy>
</channel-type>

<thing-type id="thingtype">
    <label>Sample Thing</label>
    <description>Thing type which overrides the auto update policy of a channel</description>
    <channels>
      <channel id="instance" typeId="channel">
        <autoUpdatePolicy>default</autoUpdatePolicy>
      </channel>
    </channels>
</thing-type>

The following policies are supported:

  • veto: No automatic state update should be sent by the framework. The thing handler will make sure it sends a state update and it can do it better than just converting the command to a state.
  • default: The binding does not care and the framework may do what it deems to be right. The state update which the framework will send out normally will correspond the command state anyway. This is the default if no other policy is set explicitly.
  • recommend: An automatic state update should be sent by the framework because no updates are sent by the binding. This usually is the case when devices don't expose their current state to the handler.

# Bridges and Thing Descriptions

Every binding has to provide meta information about which bridges and/or _Thing_s it provides and how their relations to each other are structured. In that way a binding could describe that it requires specific bridges to be operational or define which channels (e.g. temperature, color, etc.) it provides.

Every bridge or Thing has to provide meta information such as label or description. The meta information of all bridges and _Thing_s is accessible through the org.openhab.core.thing.binding.ThingTypeProvider service.

Bridge and Thing descriptions must be placed as XML file(s) (with the ending .xml) in the bundle's folder /OH-INF/thing/. The full Java API for bridge and Thing descriptions can be found in the Java package org.openhab.core.thing.type.

# XML Structure for Thing Descriptions

<?xml version="1.0" encoding="UTF-8"?>
<thing:thing-descriptions bindingId="bindingID"
    xmlns:xsi="https://www.w3.org/2001/XMLSchema-instance"
    xmlns:thing="https://openhab.org/schemas/thing-description/v1.0.0"
    xsi:schemaLocation="https://openhab.org/schemas/thing-description/v1.0.0
        https://openhab.org/schemas/thing-description-1.0.0.xsd">

  <bridge-type id="bridgeTypeID" listed="{true|false}" extensible="channelTypeId1,channelTypeId2,...">
    <supported-bridge-type-refs>
      <bridge-type-ref id="bridgeTypeID" />
      ...
    </supported-bridge-type-refs>

    <label>String</label>
    <description>String</description>
    <category>String</category>

    <channels>
      <channel id="channelID" typeId="channelTypeID" />
      OR
      <channel id="channelID" typeId="channelTypeID">
        <label>String</label>
        <description>String</description>
      </channel>
      ...
    </channels>
    OR
    <channel-groups>
      <channel-group id="channelGroupID" typeId="channelGroupTypeID" />
      OR
      <channel-group id="channelGroupID" typeId="channelGroupTypeID">
        <label>String</label>
        <description>String</description>
      </channel-group>
      ...
    </channel-groups>

    <properties>
        <property name="propertyName">propertyValue</property>
        ...
    </properties>
    <representation-property>propertyName</representation-property>

    <config-description>
      ...
    </config-description>
    OR
    <config-description-ref uri="{binding|thing-type|channel-type|any_other}:bindingID:..." />
  </bridge-type>

  <thing-type id="thingTypeID" listed="{true|false}" extensible="channelTypeId1,channelTypeId2,...">
    <supported-bridge-type-refs>
      <bridge-type-ref id="bridgeTypeID" />
      ...
    </supported-bridge-type-refs>

    <label>String</label>
    <description>String</description>
    <category>String</category>

    <channels>
      <channel id="channelID" typeId="channelTypeID" />
      OR
      <channel id="channelID" typeId="channelTypeID">
        <label>String</label>
        <description>String</description>
      </channel>
      ...
    </channels>
    OR
    <channel-groups>
      <channel-group id="channelGroupID" typeId="channelGroupTypeID" />
      OR
      <channel-group id="channelGroupID" typeId="channelGroupTypeID">
        <label>String</label>
        <description>String</description>
      </channel-group>
      ...
    </channel-groups>

    <properties>
        <property name="propertyName">propertyValue</property>
        ...
    </properties>
    <representation-property>propertyName</representation-property>

    <config-description>
      ...
    </config-description>
    OR
    <config-description-ref uri="{binding|thing-type|channel-type|any_other}:bindingID:..." />
  </thing-type>

  <channel-type id="channelTypeID" advanced="{true|false}">
    <item-type>Dimmer</item-type>
    OR
    <kind>trigger</kind>
    <label>String</label>
    <description>String</description>
    <category>String</category>

    <tags>
      <tag>String</tag>
      ...
    </tags>

    <state min="decimal" max="decimal" step="decimal" pattern="String" readOnly="{true|false}">
      <options>
        <option value="String" />
        OR
        <option value="String">String</option>
        ...
      </options>
    </state>
    OR
    <event>
      <options>
        <option value="String" />
        OR
        <option value="String">String</option>
        ...
      </options>
    </event>

    <command>
      <options>
        <option value="String" />
        OR
        <option value="String">String</option>
        ...
      </options>
    </command>

    <config-description>
      ...
    </config-description>
    OR
    <config-description-ref uri="{binding|thing-type|channel-type|any_other}:bindingID:..." />
  </channel-type>

  <channel-group-type id="channelGroupTypeID">
    <label>String</label>
    <description>String</description>
    <category>String</category>

    <channels>
      <channel id="channelID" typeId="channelTypeID" />
      ...
    </channels>
  </channel-group-type>

  ...

</thing:thing-descriptions>
Property Description
thing-descriptions.bindingId The identifier of the binding this types belong to mandatory

Bridges and Things:

Property Description
bridge-type.id / thing-type.id An identifier for the bridge/Thing type mandatory
bridge-type.listed / thing-type.listed Denotes if user interfaces should list the bridge/Thing, e.g. for pairing optional, defaults to true
bridge-type.extensible / thing-type.extensible If the bridge/Thing supports a generic number of channels the allowed channelTypeIds can be listed here. This provides a hint for UIs to support adding/removing channels. Channel groups are not supported. optional
supported-bridge-type-refs The identifiers of the bridges this bridge/Thing can connect to optional
bridge-type-ref.id The identifier of a bridge this bridge/Thing can connect to mandatory
label A human-readable label for the bridge/Thing mandatory
description A human-readable description for the bridge/Thing optional
category Category this bridge/Thing belongs to, see categories) optional
channels The channels the bridge/Thing provides optional
channel.id An identifier of the channel the bridge/Thing provides mandatory
channel.typeId An identifier of the channel type definition the bridge/Thing provides mandatory
label A human-readable label for the channel optional
description A human-readable description for the channel optional
channel-groups The channel groups defining the channels the bridge/Thing provides optional
channel-group.id An identifier of the channel group the bridge/Thing provides mandatory
channel-group.typeId An identifier of the channel group type definition the bridge/Thing provides mandatory
properties Name/value pairs for properties to be set to the thing optional
representation-property The name of the property that contains a unique identifier of the thing optional
config-description The configuration description for the bridge/Thing within the ConfigDescriptionRegistry optional
config-description-ref The reference to a configuration description for the bridge/Thing within the ConfigDescriptionRegistry optional
config-description-ref.uri The URI of the configuration description for the bridge/Thing within the ConfigDescriptionRegistry mandatory

Channels:

Property Description
channel-type.id An identifier for the channel type mandatory
channel-type.advanced The flag indicating if this channel contains advanced functionalities which should be typically not shown in the basic view of user interfaces optional, default: false
kind The kind of channel. state for channels which have a state, trigger for trigger channels. state is the default.
item-type An item type of the channel. All item types are specified in ItemFactory instances. The following items belong to the core: Switch, Rollershutter, Contact, String, Number, Dimmer, DateTime, Color, Image, Location, Player, Call. mandatory if kind state, which is the default
label A human-readable label for the channel mandatory
description A human-readable description for the channel optional
category The category for the channel, e.g. TEMPERATURE optional
tags A list of default tags to be assigned to bound items optional
tag A tag semantically describes the feature (typical usage) of the channel e.g. AlarmSystem. There are no pre-default tags, they are custom-specific mandatory
state The restrictions of an item state which gives information how to interpret it optional
state.min The minimum decimal value of the range for the state optional
state.max The maximum decimal value of the range for the state optional
state.step The increasing/decreasing decimal step size within the defined range, specified by the minimum/maximum values optional
state.pattern The pattern following the printf syntax to render the state optional
state.readOnly The flag indicating if the state is read-only or can be modified optional, default: false
options A list restricting all possible values optional
option The description for the option optional
option.value The value for the option. Note that the value may be outside of the range specified in the min/max if this is specified. mandatory
command Commands this channel will send to the binding. This is used to model "write-only" channels and gives UIs a hint to display push-buttons without state optional
options A list defining the possible commands optional
option The description for the option optional
option.value The value for the option. This is the actual command send to the channel. mandatory
event The restrictions of a trigger event which gives information how to interpret it optional
autoUpdatePolicy The auto update policy to use optional
config-description The configuration description for the channel within the ConfigDescriptionRegistry optional
config-description-ref The reference to a configuration description for the channel within the ConfigDescriptionRegistry optional
config-description-ref.uri The URI of the configuration description for the channel within the ConfigDescriptionRegistry mandatory

Channel Groups:

Property Description
channel-group-type.id An identifier for the channel group type mandatory
label A human-readable label for the channel group mandatory
description A human-readable description for the channel group optional
category The category for the channel group, e.g. TEMPERATURE optional
channels The channels the bridge/Thing provides mandatory
channel.id An identifier of the channel the bridge/Thing provides mandatory
channel.typeId An identifier of the channel type definition the bridge/Thing provides mandatory

The full XML schema for Thing type descriptions is specified in the https://openhab.org/schemas/thing-description-1.0.0.xsd (opens new window) openHAB thing description XSD file.

Hints:

  • Any identifiers of the types are automatically mapped to unique identifiers: bindingID:id.
  • The attribute uri in the section config-description is optional, it should not be specified in bridge/Thing/channel type definition files because it's an embedded configuration. If the uri is not specified, the configuration description is registered as thing-type:bindingID:id or channel-type:bindingID:id otherwise the given uri is used.s
  • If a configuration description is already specified somewhere else and the bridge/Thing/channel type wants to (re-)use it, a config-description-ref should be used instead.

# Updating Thing Types

Sometimes, when bindings evolve, thing-types need to be modified. Since managed things store their structure in a database at the time they are created, only updating the XML is not sufficient. Developers can add instructions for the framework to update these things during initialization.

The instructions are provided as XML in the OH-INF/update folder. The file name can be freely chosen and the file itself can contain instructions for one or more thing-types. Instructions for the same thing-type MUST NOT be added in different files.

Update instructions are available for adding, removing or updating channels or channel-groups. Changes to configuration parameters don't need update instructions and are performed automatically.

The following update instruction changes the channel-type for the battery-level channel to system:battery-level.

<?xml version="1.0" encoding="UTF-8" standalone="yes" ?>
<update:update-descriptions xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
                            xmlns:update="https://openhab.org/schemas/update-description/v1.0.0"
                            xsi:schemaLocation="https://openhab.org/schemas/update-description/v1.0.0 https://openhab.org/schemas/update-description-1.0.0.xsd">

  <thing-type uid="deconz:batterysensor">
    <instruction-set targetVersion="1">
      <update-channel id="battery_level">
        <type>system:battery-level</type>
      </update-channel>
    </instruction-set>
  </thing-type>

</update:update-descriptions>

Different instructions can be combined in one instruction-set. The following removes the water_level channel from foo:pool things and adds a new chlorine level

<?xml version="1.0" encoding="UTF-8" standalone="yes" ?>
<update:update-descriptions xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
                            xmlns:update="https://openhab.org/schemas/update-description/v1.0.0"
                            xsi:schemaLocation="https://openhab.org/schemas/update-description/v1.0.0 https://openhab.org/schemas/update-description-1.0.0.xsd">

  <thing-type uid="foo:pool">
    <instruction-set targetVersion="1">
      <remove-channel id="water_level">
      </remove-channel>
      <add-channel id="chlorine">
        <type>foo:concentration</type>
        <label>Chlorine Concentration</label>
      </add-channel>
    </instruction-set>
  </thing-type>

</update:update-descriptions>

In addition to the update instructions, the thing-type definition needs to add a property thingTypeVersion to prevent newly created things from being modified:

<thing-type id="batterysensor">
  <supported-bridge-type-refs>
    <bridge-type-ref id="deconz"/>
  </supported-bridge-type-refs>
  <label>Battery Sensor</label>
  <channels>
    <channel typeId="system.battery-level" id="battery_level"/>
    <channel typeId="last_updated" id="last_updated"/>
  </channels>
  <properties>
    <property name="thingTypeVersion">1</property>
  </properties>
  <representation-property>uid</representation-property>
  <config-description-ref uri="thing-type:deconz:sensor"/>
</thing-type>

Modifying or removing update instructions after they have been merged is not permitted, only additions are allowed. Each new contribution of update instructions MUST increase the thingTypeVersion, even if there was no release. The thingTypeVersion is bound to a thing-type, different thing types may have different versions.

The full XML schema for update instructions can be found here: https://www.openhab.org/schemas/update-description-1.0.0.xsd (opens new window).

Caught a mistake or want to contribute to the documentation? Edit this page on GitHub (opens new window)