Using REST API of ctrlX CORE

[CodeShepherd]

Overview

This blog will show you how to use the REST API of a ctrlX CORE or a ctrlX CORE^virtual to read out data of the ctrlX Data Layer. With this interface the control can also be configured and axis be commanded (see hints and the end).

Preparation

• A real or a ctrlX CORE^virtual control has to be connected to the network.
• Installation of a REST client is expected. In this Example Google Chrome extension YARC! is used.
• Make sure the browser is allowed to connect to the control via https by trusting its certificate.
  Trust certificate of ctrlX core
• Optional: Installation of ctrlX WORKS. Please have a look at the corresponding documentation or video to see how to do this.
  
  

Using REST (Representational State Transfer) API (Application Programming Interface)

1. Check connection to your control with your network folder of windows or use our tool ctrlX WORKS. There all controls connected to your PC and their IPs are shown.
   
   

2. Authorize:
   The system is secure by design so to get access to the control you will always have to authorize your requests with a security token.
   
   To get it send an https POST request to the authorization server of the ctrlX CORE (https://192.168.1.1/identity-manager/api/v1/auth/token). The payload has to be a permitted user and a password written as a JSON (JavaScript Object Notation) object. The standard ones are “boschrexroth” ({"name":"boschrexroth","password":"boschrexroth"}). Additionally the “Content-Type” “application/json” has to be added to the request header to tell the server how data should be interpreted.
   
   The response will show the number 201 that means successfully created and includes a JSON object with the token of the type bearer.

   
3. Use this token get access to all data of the ctrlX CORE by adding it to the request header as "Authorization" changed to the format "Bearer xxxxx...".
   
   
4. METADATA:
   To get to know which command can be used on which ctrlX Data Layer node additional information can be read out via a GET request of the type metadata. Exemplary the axs node of motion (https://192.168.1.1/automation/api/v1/motion/axs?type=metadata). Response is a JSON object including all information. Hint: read = GET, write = PUT, create = POST, delete = DELETE.
   

    

5. BROWSE:
   To read all actual known axes in the ctrlX MOTION system by sending an https GET request of the type browse to the axes area of the motion (https://192.168.1.1/automation/api/v1/motion/axs?type=browse) to get to know which ones are available. Response is a JSON object including the type "arstring" and the list of axis names.
   Send Browse Request
   
   

6. GET:
   Now send an https GET request to read out the actual values of the axis (https://192.168.1.1/automation/api/v1/motion/axs/Axis_1/state/values/actual/) found by browsing. Here the response contains a JSON object with all the data included.
   Get Axis Values
   
   

7. PUT:
   Now send an https PUT request to write a limit of the axis (https://192.168.1.1/automation/api/v1/motion/axs/Axis_1/cfg/lim/pos-min) found by browsing. As payload we have to hand over a JSON object with the data type and the value.
   

    

8. POST:
   Now send an https POST request to create new axis (https://192.168.1.1/automation/api/v1/motion/axs). As payload we have to hand over a JSON object with the data type and the value.
   

    

Notes

• When using a ctrlX CORE^virtual in port forwarding mode the address will change to https://localhost:PORT/... (PORT in standard is 8443)
• REST = Representational State Transfer
  is a software architectural style that defines a set of constraints to be used for creating Web services.
• API = Application Programming Interface
  is a computing interface to a software component or a system, that defines how other components or systems can use it.
• JSON = JavaScript Object Notation
  is an open standard file format, and data interchange format, that uses human-readable text to store and transmit data.
• The old version of the REST API is using v1.0 and the new one v1 in the corresponding links.
• The validity time of the authorization token can be set in the "Users & Permissions" area under "Session Policies". The will automatically expire with a control reboot.
• A browse request can be send at any node of the ctrlX Data Layer.
• Any standard browser is also using the REST API. With the developer tools, the used commands can be visualized.
  REST API in Browser

Related links

• Video "Using REST API of ctrlX CORE"
• Home page of JSON
• Documentation "ctrlX CORE Runtime, Application Manual"
  • chapter " ctrlX Data Layer -> ctrlX Data Layer Rest interface"
• Forum ctrlX CORE

yarc_favorites.zip

[lg-lima]

Very useful info! Kudos 🤖

[TK2588]

I think you have to add the port 8443 in the lastest software version to the URL:

https://localhost:8443/identity-manager/api/v1/auth/token

If yes, please adapt the description. Thank you!

[CodeShepherd]

This is only necessary when you run a ctrlX CORE^virtual in port forwarding mode. Be aware that the port is freely chooseable in that case.

But thanks for the remark!

[arjan_de_meijer]

Can you collaborate on this example by also putting data to the layer! Authentication and reading are possible; however, it does not want to put (new/updated) information to the data layer. For instance, create a simple int, float, bool to an arbitrary address in the data layer that does not already exist.

[CodeShepherd]

It is not possible to add nodes via REST interface anywhere you like. This functionality has to be provided by an app e.g. PLC, motion or customer apps. There it is possible to have node that supports creating subnodes like the "motion/axs". There you can post a string and subflows are generated by the app.

[arjan_de_meijer]

@CodeShepherd, thanks for the quick response! Does this imply that the REST API's use case is mainly/only for reading the Data Layer information? I would assume a CRUD functionality of the REST API, but perhaps this is safer in terms of control!

[CodeShepherd]

The REST API itself provides this interface. But the function that will be executed when using https POST,PUT,GET (OnCreate, OnWrite, OnRead) and so on is implemented e.g. in C++ in the apps. The datalayer itself does not hold any data it is a broker. See FAQ for ctrlX Data Layer.

[CodeShepherd]

METADATA, PUT, POST commands and YARC favourite export added.