Variable over http and push message

Developer's Corner Scene Scripting
#1

[code]local command = “wget -q -T=30 -t 10 -O /dev/null ‘http://IP/arduino/sensor/1’”
local tempString = io.popen(command)
local temp=tonumber(tempString)

if temp > 20.5
then
luup.call_action(“urn:intvelt-com:serviceId:HWPush1”, “SendMessage”, {Msg = … tempString … }, 274)
end[/code]

It always fails. The reading seems to be good but the “if” is always false. Furthermore the message won’t send the actual value.

Thanks for any help

#2

I think you should investigate just what is being returned in tempString. You could try logging it:

luup.log("tempString: " .. tostring(tempString))

Also I have noticed that Vera has an issue with the way you have written your if statement. Try:

if temp > 20.5 then luup.call_action("urn:intvelt-com:serviceId:HWPush1", "SendMessage", {Msg = .. tempString .. }, 274) end

#3

Thanks I will have to check a lot of code for if…then.

What do you think about this:

luup.log("tempString: " .. tostring(tempString)) <0x31dc9680>

#4
What do you think about this: Code: [Select] luup.log("tempString: " .. tostring(tempString)) <0x31dc9680>

What was the actual log message? Did it include the word table?

#5

I just used scp to copy the log and this was the last line, so yes.

#6

If the log entry looked like this:

50 04/06/14 11:31:11.701 luup_log:0: tempString: table: 0x1da8498 <0x31feb680>

Then you will need to figure-out the structure of the table so you can extract the data you want. If it was me, I would do it using LuaTest and print(pretty(tempString))

#7

No idea what do do now.

It always worked with this:

local http = require("socket.http") http.TIMEOUT = 5 local status, result = http.request("http://www.domain.com/index.htm")

But since Vera crashes because of that command ::slight_smile: I choose this way. But I need the content of the page (int or string).

#8
But since Vera crashes because of that command..

That command will not cause Vera to crash - but - it adds another ongoing activity and may well tip an overloaded system into a deadlock. This can easily happen when there are multiple simultaneous run actions in progress.

#9

Ok, but what should I do? I have 24 MB of free memory…

Seriously my computer doesn’t crash just because it is using 100 % of the CPU.

#10

Looking at the log for the two minutes before a crash should show you what is happening. Problems will occur if there are plugins using run actions that take longer than a few milliseconds. The run queue is limited and, if Vera is unable to execute actions, it can gridlock and force a restart. Plugin actions that go beyond setting a few variables should use job processing.

Scenes that suspend waiting for I/O just add to the probability of gridlock.

#11

If you want to use [tt]io.popen[/tt], it works like this:

[code]local handle = io.popen(‘ls -l /’)
local result = handle:read("*a")

print (result)

handle:close()[/code]

This will work, freestanding, in a .lua file. In my case, I wrote it in test.lua, and ran it with the command line version of Lua (since it has no Vera dependencies)

eg.

root@MiOS_3000eieio:~# lua test.lua drwxr-xr-x 2 root root 757 Feb 22 2013 bin drwxr-xr-x 4 root root 1420 Apr 6 08:41 dev drwxr-xr-x 1 root root 0 Apr 6 06:00 etc -rw-r--r-- 1 root root 136369 Apr 6 08:42 foo drwxr-xr-x 1 root root 0 Feb 22 2013 lib ...

I’m using “[tt]ls[/tt]” instead of your “[tt]wget[/tt]” command, but the Lua code is the same, since they’re both just processes.

#12

Ok, looks promising, but how could I include this in a scene?

[code]
local handle = io.popen(“wget -q -T=30 -t 10 -O /dev/null ‘http://IP/arduino/sensor/1’”)
local result = handle:read("*a") --???

print (result)

handle:close()[/code]

Could I use handle in the scene? And is handle in my case the temperature 22.0?

#13

This is the snippet of code that fetches the value, just to show you how to use [tt]io.popen()[/tt]. The “result” of that call is put into a variable called result, which is a string value of whatever the OS command returned (in this case, a directory listing, but you’d call [tt]wget[/tt] instead)

It’s written in pure Lua, so it can be run from the command line so you can test/try/understand it independently of Vera. You will need to merge the snippet with the rest of your scene-logic.

Since that’s trivial, I didn’t bother with that part.

The [tt]handle:read()[/tt] call that’s in there is the bit that’s pulling in the output of the command that’s executed. The parameter, [tt]"*a"[/tt], simply tells read to pull in all the data into one [string] response.

There are loads of snippet-based examples like this on lua.org, and on lua-users.org:
http://lua-users.org/wiki/TutorialDirectory

These cover every generic topic you can imagine for learning Lua as a language. This is generally a first step before trying to understand the nuances of the Luup extensions that Vera adds.