Rest API : can't send commands with more than 1 parameter

General Development
1

Hi everyone !

I am currently working on an Android app where I am trying to send a command with the Tango rest API. Until now, I have sent commands with only 0 or 1 parameters and I didn’t experience any problem. However, I now need to send a command which has two parameters (and perhaps more later), and the command isn’t received by my device server.

When I send the command, I receive a failure with the following JSON response :

{"errors":[{"reason":"TangoApi_CANNOT_EXECUTE_COMMAND","description":"Cannot execute command SetVoltage on SAGA_NG_001\/Laser_NG\/1","severity":"PANIC","origin":"Connection.command_inout()"},{"reason":"COMMAND_TO_EQUIPMENT_FAILED","description":" - result = 3\n","severity":"ERR","origin":"EquipmentLaser_NG::psSetVoltage"}],"quality":"FAILURE","timestamp":1624269539928}
{"reason":"TangoApi_CANNOT_EXECUTE_COMMAND","description":"Cannot execute command SetVoltage on SAGA_NG_001\/Laser_NG\/1","severity":"PANIC","origin":"Connection.command_inout()"}
{"reason":"COMMAND_TO_EQUIPMENT_FAILED","description":" - result = 3\n","severity":"ERR","origin":"EquipmentLaser_NG::psSetVoltage"}

I send the command with the following uri : “http://:8844/tango/rest/rc4/hosts/127.0.0.1/20000/devices/SAGA_NG_001/Laser_NG/1/commands/SetVoltage”

I don’t see in the previous JSON response what is the reason for the command to not be able to be executed.

Here are some points that could be importants :

  • I am using rest server rc4-0.1. I tried to switch to the rest server 1.22 by replacing the .jar file but I haven’t been able to make it work.
  • If I send the same commands, but with no or one parameter, they are also not received by the device. I don’t understand this behaviour, as I think that the device should receive the command and throw an error while parsing the parameters (because there are some missing parameters). However, when I put no or one parameter, I don’t receive the previous JSON response, but instead of that I get a failure with no JSON and the following message : “java.io.EOFException: No content to map to Object due to end of input”.
    I think that the problem is linked to the commands who take 2 parameters, not to the parameters itself.

Do you have any idea about the reason of my problem ?

Best regards,
Nicolas Mienné
Thales Group.

2

Hi Nicolas,

I think you need to send an array when you want multiple input arguments, the same you would do it in pure Tango.

What was the problem with 1.22 exactly I wonder? That should work as you said - just replacing the jar

Cheers,

3

Hi Igor, thank you for your quick answer.

  • The arguments I give are in a JSON array format : “[0,7]”.
  • When I tried to use the 1.22 API with the new jar, I did see at uri “http://:8844/tango/rest/v11/hosts” :

    JSON {"rc4":"http://<ipAddress>:8844/tango/rest//rc4","v10":"http://<ipAddress>:8844/tango/rest//v10","v11":"http://<ipAddress>:8844/tango/rest//v11"}

    With the old jar, there was only the “rc4” key, so the new jar is successfully launched. However, when I go to “http://:8844/tango/rest/rc4/hosts”, I have the following error, and I have the same issue with “v10” and “v11” :

    JSON {"errors":[{"reason":"No Tango host was specified","description":"","severity":"","origin":"org.tango.web.server.providers.TangoDatabaseProvider.filter(TangoDatabaseProvider.java:69)"}],"quality":"FAILURE","timestamp":1624028816045}


    My TANGO_HOST environment variable is correctly set and I also give the tango host in parameter when I launch the jar. Here is my bat command for launching the jar :

    bat start java -jar -DTANGO_HOST=127.0.0.1:20000 rest-server-1.22.jar test

[edit] : in order to run the 1.22 jar, I needed to update my Java Runtime. I installed the OpenJDK11.

Cheers,
Nicolas

4

OK, I see

Since some version rest-server does not have any default hosts, so you have to specify one in the URL e.g. “http://:8844/tango/rest/v11/hosts/localhost;port=20000”. Please note port matrix parameter, you need this to specify non-default Tango host port in v1.0&v1.1 or using old syntax “http://:8844/tango/rest/rc4/hosts/localhost/20000” for rc4

Commands should work when you pass an array. Are you able to execute those commands without REST api?

5

Indeed, with the url formatted as you said, I am able to browse my Tango database in v1.1 using Firefox. However it seems that the API I use for the REST communication can’t parse the response from the new version. After sending the command, in rc4 I get no error, in v11 I get :

For your second question : yes, these commands work with non-REST API and also on AtkPanel

6

Could you please specify which Tango type is used for the input argument of your command?

7

The command takes a DevVarUShortArray. I tried all the following syntaxes to give the parameters, which all result to the same issue :
“[0,1]”, “0,1”, “{0,1}”, “(0,1)”

8

Hi,

I have tested against TangoTest DevVarUShortArray command and it works.

Request


PUT http://localhost:10001/tango/rest/v11/hosts/localhost/devices/sys/tg_test/1/commands/DevVarUShortArray
Accept: application/json
Authorization: Basic dGFuZ28tY3M6dGFuZ28=

{
  "host":"localhost:10000",
  "device":"sys/tg_test/1",
  "name":"DevVarUShortArray",
  "input":[0,1]
}

Response:


HTTP/1.1 200
Cache-Control: private
Expires: Thu, 01 Jan 1970 00:00:00 GMT
Content-Type: application/json
Transfer-Encoding: chunked
Date: Wed, 23 Jun 2021 19:26:45 GMT
Keep-Alive: timeout=20
Connection: keep-alive

{
  "host": "localhost:10000",
  "device": "sys/tg_test/1",
  "name": "DevVarUShortArray",
  "input": [
    0,
    1
  ],
  "output": [
    0,
    1
  ]
}

Response code: 200; Time: 2121ms; Content length: 107 bytes

Please note the correct argument - is an object, see device commands

9

Thank you for your answer.

I couldn’t find the documentation of the REST API from the gitHub repository, the link at the end of your message helped me a lot.

I have been able to reproduce with a REST client the issue I had in V11 with my Android app (the com.google.gson.JsonParseException) : it is the response we get when “host” and “name” parameters are missing.

With the REST client I use for testing, I’ve been able to succesfully send the command with 2 parameters. I’ll let you know if this also works with my Android app, but I’m pretty confident that it will work :smiley:

10

Hi, the documentation is here: Tango REST API v1.1 — Tango REST API specification 1.1 documentation

All the best, Piotr

11

Hi,

Thanks you for the link pgoryl, so it seems like there are 2 differents links for the same documentation (here and here)

Coming back to my Android app, I had a few issues to make my Android app work with the new 1.22 jar but it is finally working ! Thank you for your help :slight_smile: