# HTTP Binding
![](/logos/http.png)
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 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). |
authMode | no | BASIC | Authentication mode, BASIC , BASIC_PREEMPTIVE 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. |
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
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 |
---|---|---|---|
play | yes | - | A special value that represents PLAY |
pause | yes | - | A special value that represents PAUSE |
next | yes | - | A special value that represents NEXT |
previous | yes | - | A special value that represents PREVIOUS |
fastforward | yes | - | A special value that represents FASTFORWARD |
rewind | 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 (opens new window).
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" ]
}