FEWS PI-JSON format

Introduction

The FEWS PI-JSON format is following the FEWS PI-XML format as described in http://fews.wldelft.nl/schemas/version1.0/pi-schemas/.

Since 2017.02 the PI-JSON format is supported for the following GET resources in the PI REST Web Service:

The following conventions have been used to make PI-XML compatible with the JSON format:

consistent use of camel case. Where some PI-XML elements start with a upperCase, the camelCase convention is used for all JSON objects. For example the timeSeries.xsd of PI-XML defines the root element as TimeSeries. In PI-JSON it is called timeSeries. All JSON properties use the camelCase convention.
Implicit object names are left out. For example in the timeSeries.xsd of PI-XML timeSeries is defined as a sequence of series elements. In PI-JSON the element "series" is left out.
Values are always quoted.
XML attributes are transformed to JSON properties.

Python Example

PI-JSON can be easily read using Python. The following example shows how to read PI-JSON timeseries using the requests module. The result contains a dictionary with timeSeries.

import requests
 
url = 'http://localhost:8080/FewsWebServices/rest/fewspiservice/v1/timeseries'

params = dict(
    documentVersion='1.23',
    documentFormat='PI_JSON'
)
response = requests.get(url=url, params=params)
data = response.json()

print('All timeSeries:', data)

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FEWS PI-JSON format

Introduction

Python Example