Displaying Text if HTTP Device is Offline

Setup, Configuration and Use Beginners
,
1

Rpi, Openhab 2.5:

Using HTTP binding, I have a flowmeter which provides a rotation count as an HTTP response.
My sitemap reports the rotation count.
This works fine.

However am trying to configure my setup such that if this device is offline, then my sitemap reports something along the lines of “Offline since [date & time]” instead of a rotation count.

I have attempted to create code to achieve this using Network binding, though appear to be having some trouble (although I am using Network binding for presence detection elsewhere - it seems to work fine).

My items as follows:

Number FlowVolume_data_1 { http="<[http://192.168.0.147:81/:8000:REGEX(.*?<html>(.*?)</html>.*)]" }
Switch Flowmeter_1 { channel="network:pingdevice:Flowmeter_1:online" }
String Flowmeter_1_Message

Things as follows:

Thing network:pingdevice:Flowmeter_1 "Flowmeter_1" [ hostname="192.168.0.147" ]

Sitemap as follows:

Text item=Flowmeter_1_Message label="Rotations 1 - modified [%s]" icon="faucet"

Rules as follows:

rule "FlowVolume_Offline"

when
	Item Flowmeter_1.state changed
then
	if (Flowmeter_1.state == ON)
	{
		Flowmeter_1_Message.sendCommand(FlowVolume_data_1.state.toString)
	}
	else
	{
		Flowmeter_1_Message.sendCommand("Offline since {date}, sorry")
	}
end

Any help welcome. The “Modified” entry - intended to display the text (Offline since…) does not appear to change from a rotations count (fixed at some point in the past).
In addition, I have no idea how to add in the date variable - though I believe this can be done using a channel in HTTP…

2

If you want to display your current data in the message, you’d want to run the rule every time the data changes. You can have more than one trigger.

3

Thank you - helped me work it out.
Posting the code for a straightforward solution below (Rules file - rest unchanged)

rule "FlowVolume_Offline"

when
	Item Flowmeter_1 changed or
	Item FlowVolume_data_1 changed
then
	if (Flowmeter_1.state == ON)
	{
		Flowmeter_1_Message.sendCommand(FlowVolume_data_1.state.toString)
	}
	else
	{
		Flowmeter_1_Message.sendCommand("Offline since "+Flowmeter_1_lastseentime.state)
	}

end
4

Slightly longer solution (which achieves the text output I was looking for) below:

rule "FlowVolume_Offline1"

when
	Item Flowmeter_1 changed or
	Item FlowVolume_data_1 changed or
	Time cron "0 0 0/1 1/1 * ? *"
then
	if (Flowmeter_1.state == ON)
	{
		Flowmeter_1_Message.sendCommand(FlowVolume_data_1.state.toString)
	}
	else
	{
		var String timeMessage
		
		var Number yearNow = now.getYear
		
		var Number monthNow = now.getMonthOfYear 
		
		var Number dayNow = now.getDayOfMonth	
		
		var Number dayOfYearNow = now.getDayOfYear
		
 		var Number yearLastSeen = Integer::parseInt(Flowmeter_1_lastseentime.state.format("%1$tY"))	
 		
 		var Number monthLastSeen = Integer::parseInt(Flowmeter_1_lastseentime.state.format("%1$tm"))		
 		
 		var Number dayNameLastSeen = Flowmeter_1_lastseentime.state.format("%1$tA")		
 		
 		var Number dayLastSeen = Integer::parseInt(Flowmeter_1_lastseentime.state.format("%1$te"))		
 		
 		var Number hour12LastSeen = Integer::parseInt(Flowmeter_1_lastseentime.state.format("%1$tl"))		
 		
 		var String minuteLastSeen = Flowmeter_1_lastseentime.state.format("%1$tM")	
 		
 		var String meridianLastSeen = Flowmeter_1_lastseentime.state.format("%1$tp")	

 		var Number dayOfTheYearLastSeen = Integer::parseInt(Flowmeter_1_lastseentime.state.format("%1$tj")) 			 		

 		
 		if ((yearNow-yearLastSeen ==0) && (monthNow-monthLastSeen ==0) &&(dayNow-dayLastSeen ==0))
 		{
 			timeMessage="Offline since "+hour12LastSeen+":"+minuteLastSeen+meridianLastSeen	
 		}		 		
		
 		if ((yearNow-yearLastSeen ==0) && (dayOfYearNow-dayOfTheYearLastSeen ==1))
 		{
 			timeMessage="Offline since "+hour12LastSeen+":"+minuteLastSeen+meridianLastSeen+" yesterday"
 		}

 		if ((yearNow-yearLastSeen ==0) && (dayOfYearNow-dayOfTheYearLastSeen ==2))
 		{
 			timeMessage="Offline since the day before yesterday"
 		}
		
		if ((yearNow-yearLastSeen ==0) && (dayOfYearNow-dayOfTheYearLastSeen >=3) && (dayOfYearNow-dayOfTheYearLastSeen <=7))
 		{
 			timeMessage="Offline since "+dayNameLastSeen+" "+meridianLastSeen
 		}
		
		if ((yearNow-yearLastSeen !=0) || (dayOfYearNow-dayOfTheYearLastSeen >=8))
 		{
 			timeMessage="Offline for ages"
 		}
 		
 		Flowmeter_1_Message.sendCommand("Was "+FlowVolume_data_1.state+": "+timeMessage)

	}

end

If there is a more elegant solution I 'd be grateful to know; this feels like quite a lot of code for a simple output.

I also don’t quite understand why the variable “FlowVolume_data_1.state” in the last line appears to work (or persist) even though the device is offline… I do have a persistence database set up - is it automatically pulling from that without me being aware?

thanks

5

Once an Item state has been set, it stays that way. Was there some reason you expected it to change?

If you wanted it to change, you could for example use the expire binding to update to UNDEF after an hour with no updates, or similar. Or have your rule do that, as you are already detecting the condition.

6

thanks.
I guess I was expecting it to show an error.
Will think about the Expire idea; appreciate the suggestion.

7

If your http data Item showed an error, you wouldn’t need your separate ping.
Some bindings will set state UNDEF for certain failures by design, but not that one.

UNDEF can be useful, note that it doesn’t get persisted which can help suppress false data records, depending what you’re doing with your data.

8

I just cleared cache and upgraded to Openhab 2.5.3, but the above code now appears to be broken.

Error log is as follows:

Rule ‘FlowVolume_Offline1’ : Y != java.lang.String

When I comment out (in the code above), the following:

var Number yearLastSeen = Integer::parseInt(Flowmeter_1_lastseentime.state.format("%1$tY"))

then the error changes to:

Rule ‘FlowVolume_Offline1’ : m != java.lang.String

and so on.
So it appears that something to do with the date/time code is off.
Did I forget to include an addon when I updated Openhab?
Grateful for any help.

thanks

9

It would be helpful to your understanding of your problem to find out what that value is, at the time the rule runs.
logInfo("test", "Last seen " + Flowmeter_1_lastseentime.state.toString)

Or you can interrogate Items at any time using the REST API

10

Cheers. Figured it out. Silly error - caused by other changes to the code not shown here.