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How to build the API connection via HTTP?

Question asked by douba on Apr 15, 2019
Latest reply on Apr 20, 2019 by douba

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Hi, everyone,

How are you!

Below is the connection description for my test instrument.

How to setup the connection in the VEE? thanks a lot!

Initializing the Connection (Obtaining Authorization)
Before any commands will be accepted by the API web service, your application must first
open a connection to the application and retrieve the authorization token. This token is
dynamically created at each PIM Web Engine launch, and so must be captured dynamically
within your application in order to allow authorized commands to the PIM API web service.
Retrieve the token by sending an HTTP request (either GET or POST) to the following URL:
http://<controller>/api/connect/<Legacy?>

Regards,

Stan Bischof Apr 15, 2019 9:23 AM

Correct Answer

Here's something to get you started. You'll need to find out the data format of the token and modify the READ transaction accordingly, but otherwise this part should be quite simple. Similar transactions for your commands.

########################################################

(saveFormat "7.0")
(date "Mon 15/Apr/2019 09:20:00 ")
(veerev "7.0.6310.0")
(platform "PC")
(execMode v6)
(filterNAN 0)
(workspaceStackingOrder M)
(SaveCF no)
(device 0 ROOTCONTEXT
(properties
(trigMode deg)
(nextID 1)
(popupTitleText "Untitled")
(popupMoveable 1))
(deviceList
(device 0 TOFROMSOCKET
(properties
(name "get token")
(transactions 2 "WRITE TEXT \"GET http://controller/api/<Legacy?>\" EOL"
"READ TEXT inst_token CHAR:1 ARRAY:10"))
(interface
(output 1
(name "inst_token")
(optional yes))
(output 2
(type exception)
(name "Error")
(lock name constraints)
(optional yes)))
(implementation
(attr iopath socket "connect" "instrument_ip" 80
(readTerm "\n")
(fs " ")
(eol "\n")
(multiField fullSyntax)
(arrayFormat block)
(timeout 10)
(byteOrder 0))))
(configuration))
(contextCarrier
(wndOrigin 2 2)
(wndState res)
(active detail)
(detail
(extent 1212 730)
(anchorPt 0 0)
(configuration
(devCarrierFor 0
(active open)
(icon
(extent 55 25))
(open
(extent 374 146))
(terminals on)
(pinCenter 290 190))))
(numberFormats
(realFormat standard)
(realSigDigits 4)
(realRadixSpec 4)
(integerBase decimal))))

########################################################

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Stan Bischof Apr 15, 2019 9:23 AM

########################################################

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Stan Bischof @ Stan Bischof on Apr 15, 2019 11:41 AM

I should note though, that the answer to your actual query (how to implement opening the instrument and requesting the token) is simple enough, what you are actually trying to do (instrument control via the secure web interface) my be much more challenging. In particular, the nature of the token itself and how it is to be used could make things interesting indeed. If you are really lucky it is just a matter of reading the bits, saving them, then sending as preamble for instructions, which would be simple enough. If more is needed, like verifying signatures or dealing with https after the initial connection, then that's where the hassle could be. Note that this same approach is how you would address most any http site.

Stan

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douba @ Stan Bischof on Apr 15, 2019 7:41 PM

Hi Stan，

Thank you very much, it works!

This instrument connection is simple without verifying signatures or dealing with https after the initial connection.

Regards,

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Stan Bischof @ douba on Apr 15, 2019 8:34 PM

Glad to be of help- lucky that there were no complications. For the edification of others you might consider posting a working example here and over in VRF.

Stan

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douba @ Stan Bischof on Apr 20, 2019 1:11 AM

Hi Stan，

The attached picture is the example to get the token, hope it is useful for learning, thanks!

Regards,

Actions

5 Replies

Stan Bischof Apr 15, 2019 9:23 AM
Unmark Correct
Correct Answer
Here's something to get you started. You'll need to find out the data format of the token and modify the READ transaction accordingly, but otherwise this part should be quite simple. Similar transactions for your commands.
########################################################
(saveFormat "7.0")
(date "Mon 15/Apr/2019 09:20:00 ")
(veerev "7.0.6310.0")
(platform "PC")
(execMode v6)
(filterNAN 0)
(workspaceStackingOrder M)
(SaveCF no)
(device 0 ROOTCONTEXT
(properties
(trigMode deg)
(nextID 1)
(popupTitleText "Untitled")
(popupMoveable 1))
(deviceList
(device 0 TOFROMSOCKET
(properties
(name "get token")
(transactions 2 "WRITE TEXT \"GET http://controller/api/<Legacy?>\" EOL"
"READ TEXT inst_token CHAR:1 ARRAY:10"))
(interface
(output 1
(name "inst_token")
(optional yes))
(output 2
(type exception)
(name "Error")
(lock name constraints)
(optional yes)))
(implementation
(attr iopath socket "connect" "instrument_ip" 80
(readTerm "\n")
(fs " ")
(eol "\n")
(multiField fullSyntax)
(arrayFormat block)
(timeout 10)
(byteOrder 0))))
(configuration))
(contextCarrier
(wndOrigin 2 2)
(wndState res)
(active detail)
(detail
(extent 1212 730)
(anchorPt 0 0)
(configuration
(devCarrierFor 0
(active open)
(icon
(extent 55 25))
(open
(extent 374 146))
(terminals on)
(pinCenter 290 190))))
(numberFormats
(realFormat standard)
(realSigDigits 4)
(realRadixSpec 4)
(integerBase decimal))))
########################################################
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- Stan Bischof @ Stan Bischof on Apr 15, 2019 11:41 AM
  Mark Correct
  Correct Answer
  I should note though, that the answer to your actual query (how to implement opening the instrument and requesting the token) is simple enough, what you are actually trying to do (instrument control via the secure web interface) my be much more challenging. In particular, the nature of the token itself and how it is to be used could make things interesting indeed. If you are really lucky it is just a matter of reading the bits, saving them, then sending as preamble for instructions, which would be simple enough. If more is needed, like verifying signatures or dealing with https after the initial connection, then that's where the hassle could be. Note that this same approach is how you would address most any http site.
  
  Stan
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- douba @ Stan Bischof on Apr 15, 2019 7:41 PM
  Mark Correct
  Correct Answer
  Hi Stan，
  
  Thank you very much, it works!
  This instrument connection is simple without verifying signatures or dealing with https after the initial connection.
  
  Regards,
  
  Qi
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  - Stan Bischof @ douba on Apr 15, 2019 8:34 PM
    Mark Correct
    Correct Answer
    Glad to be of help- lucky that there were no complications. For the edification of others you might consider posting a working example here and over in VRF.
    
    Stan
    Like • Show 0 Likes0
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    - douba @ Stan Bischof on Apr 20, 2019 1:11 AM
      Mark Correct
      Correct Answer
      Hi Stan，
      
      The attached picture is the example to get the token, hope it is useful for learning, thanks!
      
      Regards,
      
      Qi
      Like • Show 0 Likes0
      Actions

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