ERP in WS: TagHistorianData Perspective View

Integrating and Executing the SOAP Call from a User Interface

The practical value of a web service is realized when it is integrated into an application, allowing users to interact with backend data and logic through a graphical user interface (GUI). This section demonstrates the final step of the workflow: calling the configured SOAP service from a button within a Perspective View and displaying the results.

Configuring the Perspective View Button

A pre-built Perspective View will be used to complete this integration. The task is to add the script that triggers the web service call.

For time savings, this View has been mostly pre-built and only requires students to complete it by adding script functionality to the CALL SOAP Request button.

  • Navigate to Perspective → Views → Tutorial → SOAP and open the View named TagHistorianData.
  • In the Project Browser, expand the View's components, right-click on the button named btn_ws, and select Configure Events....


  • Locate the onActionPerformed event, which fires when the button is clicked.


Deconstructing the runWebService Script

The following Python script should be added to the onActionPerformed event to execute the SOAP request and process the response.

Copy Code
Python
end = system.date.now()
    start = system.date.addMinutes(end, -int(self.getSibling("Slider").props.value))
    results = system.ws.runWebService("Complete/TagHistoryAverage",
    None,
    {
          'TagAverages': {
            'startDate':start,
            'endDate':end,
            'Tank1Path': "[default]New Enterprise/Site 1/Tank 1 Level",
            'Tank2Path': "[default]New Enterprise/Site 1/Tank 2 Level",
            'Tank3Path': "[default]New Enterprise/Site 1/Tank 3 Level",
            'Tank4Path': "[default]New Enterprise/Site 1/Tank 4 Level",
            'Tank5Path': "[default]New Enterprise/Site 1/Tank 5 Level"
          }
        })
    
    dict = system.ws.toDict(results)
    data = []
    
    for key in dict['Root']['TagAveragesResponse'].keys():
        value = dict['Root']['TagAveragesResponse'][key]
        data.append({'Tank':key,'Value':value})

    self.parent.parent.getChild("Table").props.data = data

This script performs several key functions:
  • Time Range Definition: It uses system.date.now() and system.date.addMinutes() to create a dynamic start and end time based on the value of a slider component in the View.

  • Web Service Call: The system.ws.runWebService function is the core of the operation. It targets the TagHistoryAverage consumer and passes a payload dictionary containing the start date, end date, and the specific tag paths for the TagAverages operation.

  • Response Conversion: The raw SOAP response is converted into a standard Python dictionary using system.ws.toDict(), making the data much easier to work with.

  • Data Formatting: A for loop iterates through the keys and values in the response dictionary, reformatting the data into a list of dictionaries that is compatible with the Ignition Table component's data property

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