HTTP Binding
This binding allows using HTTP to bring external data into openHAB or execute HTTP requests on commands.
Supported Things
Only one thing named url is available.
It can be extended with different channels.
Thing Configuration
| parameter | optional | default | description |
|---|---|---|---|
baseURL |
no | - | The base URL (including protocol http:// or https://) for this thing. Can be extended in channel-configuration. |
refresh |
no | 30 | Time in seconds between two refresh calls for the channels of this thing. |
timeout |
no | 3000 | Timeout for HTTP requests in ms. |
bufferSize |
no | 2048 | The buffer size for the response data (in kB). |
delay |
no | 0 | Delay between two requests in ms (advanced parameter). |
username |
yes | - | Username for authentication (advanced parameter). |
password |
yes | - | Password for authentication (advanced parameter). Also used for the authentication token when using TOKEN authentication. |
authMode |
no | BASIC | Authentication mode, BASIC, BASIC_PREEMPTIVE, TOKEN or DIGEST (advanced parameter). |
stateMethod |
no | GET | Method used for requesting the state: GET, PUT, POST. |
commandMethod |
no | GET | Method used for sending commands: GET, PUT, POST. |
contentType |
yes | - | MIME content-type of the command requests. Only used for PUT and POST. |
encoding |
yes | - | Encoding to be used if no encoding is found in responses (advanced parameter). |
headers |
yes | - | Additional headers that are sent along with the request. Format is “header=value”. Multiple values can be stored as headers="key1=value1", "key2=value2", "key3=value3", |
ignoreSSLErrors |
no | false | If set to true, ignores invalid SSL certificate errors. This is potentially dangerous. |
strictErrorHandling |
no | false | If set to true, thing status is changed depending on last request result (failed = OFFLINE). Failed requests result in UNDEF for channel values. |
userAgent |
yes | (yes ) | Sets a custom user agent (default is “Jetty/version”, e.g. “Jetty/9.4.20.v20190813”). |
Note: Optional “no” means that you have to configure a value unless a default is provided, and you are ok with that setting.
Note: The BASIC_PREEMPTIVE mode adds basic authentication headers even if the server did not request authentication.
This is dangerous and might be misused.
The option exists to be able to authenticate when the server is not sending the proper 401/Unauthorized code.
Authentication might fail if redirections are involved as headers are stripper prior to redirection.
Note: If you rate-limit requests by using the delay parameter you have to make sure that the time between two refreshes is larger than the time needed for one refresh cycle.
Attention: baseUrl (and stateExtension/commandExtension) should not use escaping (e.g. %22 instead of " or %2c instead of ,).
URLs are properly escaped by the binding itself before the request is sent.
Using escaped strings in URL parameters may lead to problems with the formatting (see below).
Channels
The thing has two channels of type requestDateTime which provide the timestamp of the last successful (lastSuccess) and last failed (lastFailure) request.
Additionally, the thing can be extended with data channels.
Each item type has its own channel-type.
Depending on the channel-type, channels have different configuration options.
All channel-types (except image) have stateExtension, commandExtension, stateTransformation, commandTransformation and mode parameters.
The image channel-type supports stateExtension only.
| parameter | optional | default | description |
|---|---|---|---|
stateExtension |
yes | - | Appended to the baseURL for requesting states. |
commandExtension |
yes | - | Appended to the baseURL for sending commands. If empty, same as stateExtension. |
stateTransformation |
yes | - | One or more transformation applied to received values before updating channel. |
commandTransformation |
yes | - | One or more transformation applied to channel value before sending to a remote. |
stateContent |
yes | - | Content for state requests (if method is PUT or POST) |
mode |
no | READWRITE |
Mode this channel is allowed to operate. READONLY means receive state, WRITEONLY means send commands. |
Transformations need to be specified in the same format as
Some channels have additional parameters.
When concatenating the baseURL and stateExtension or commandExtension the binding checks if a proper URL part separator (/, & or ?) is present and adds a / if missing.
Value Transformations (stateTransformation, commandTransformation)
Transformations can be used if the supplied value (or the required value) is different from what openHAB internal types require.
Here are a few examples to unwrap an incoming value via stateTransformation from a complex response:
| Received value | Tr. Service | Transformation |
|---|---|---|
{device: {status: { temperature: 23.2 }}} |
JSONPATH | JSONPATH:$.device.status.temperature |
<device><status><temperature>23.2</temperature></status></device> |
XPath | XPath:/device/status/temperature/text() |
THEVALUE:23.2°C |
REGEX | REGEX::(.*?)° |
Transformations can be chained by separating them with the mathematical intersection character “∩”. Please note that the values will be discarded if one transformation fails (e.g. REGEX did not match).
The same mechanism works for commands (commandTransformation) for outgoing values.
color
| parameter | optional | default | description |
|---|---|---|---|
onValue |
yes | - | A special value that represents ON |
offValue |
yes | - | A special value that represents OFF |
increaseValue |
yes | - | A special value that represents INCREASE |
decreaseValue |
yes | - | A special value that represents DECREASE |
step |
no | 1 | The amount the brightness is increased/decreased on INCREASE/DECREASE |
colorMode |
no | RGB | Mode for color values: RGB or HSB |
All values that are not onValue, offValue, increaseValue, decreaseValue are interpreted as color value (according to the color mode) in the format r,g,b or h,s,v.
contact
| parameter | optional | default | description |
|---|---|---|---|
openValue |
no | - | A special value that represents OPEN |
closedValue |
no | - | A special value that represents CLOSED |
dimmer
| parameter | optional | default | description |
|---|---|---|---|
onValue |
yes | - | A special value that represents ON |
offValue |
yes | - | A special value that represents OFF |
increaseValue |
yes | - | A special value that represents INCREASE |
decreaseValue |
yes | - | A special value that represents DECREASE |
step |
no | 1 | The amount the brightness is increased/decreased on INCREASE/DECREASE |
All values that are not onValue, offValue, increaseValue, decreaseValue are interpreted as brightness 0-100% and need to be numeric only.
number
| parameter | optional | default | description |
|---|---|---|---|
unit |
yes | - | The unit label for this channel |
number channels can be used for DecimalType or QuantityType values.
If a unit is given in the unit parameter, the binding tries to create a QuantityType state before updating the channel, if no unit is present, it creates a DecimalType.
Please note that incompatible units (e.g. °C for a Number:Density item) will fail silently, i.e. no error message is logged even if the state update fails.
player
| parameter | optional | default | description |
|---|---|---|---|
playValue |
yes | - | A special value that represents PLAY |
pauseValue |
yes | - | A special value that represents PAUSE |
nextValue |
yes | - | A special value that represents NEXT |
previousValue |
yes | - | A special value that represents PREVIOUS |
fastforwardValue |
yes | - | A special value that represents FASTFORWARD |
rewindValue |
yes | - | A special value that represents REWIND |
rollershutter
| parameter | optional | default | description |
|---|---|---|---|
upValue |
yes | - | A special value that represents UP |
downValue |
yes | - | A special value that represents DOWN |
stopValue |
yes | - | A special value that represents STOP |
moveValue |
yes | - | A special value that represents MOVE |
All values that are not upValue, downValue, stopValue, moveValue are interpreted as position 0-100% and need to be numeric only.
switch
| parameter | optional | default | description |
|---|---|---|---|
onValue |
no | - | A special value that represents ON |
offValue |
no | - | A special value that represents OFF |
Note: Special values need to be exact matches, i.e. no leading or trailing characters and comparison is case-sensitive.
URL Formatting
After concatenation of the baseURL and the commandExtension or the stateExtension (if provided) the URL is formatted using the java.util.Formatter.
The URL is used as format string and two parameters are added:
- the current date (referenced as
%1$) - the transformed command (referenced as
%2$)
After the parameter reference the format needs to be appended.
See the link above for more information about the available format parameters (e.g. to use the string representation, you need to append s to the reference, for a timestamp t).
When sending an OFF command on 2020-07-06, the URL
http://www.domain.org/home/lights/23871/?status=%2$s&date=%1$tY-%1$tm-%1$td
is transformed to
http://www.domain.org/home/lights/23871/?status=OFF&date=2020-07-06
Examples
demo.things
Thing http:url:foo "Foo" [
baseURL="https://example.com/api/v1/metadata-api/web/metadata",
headers="key1=value1", "key2=value2", "key3=value3",
refresh=15] {
Channels:
Type string : text "Text" [ stateTransformation="JSONPATH:$.metadata.data" ]
}