WebDev/HTTP Beginner

Ignition
1

I've done plenty of Ignition stuff but it's all been direct connection to PLC tags. I've now got a cloud tag with a url path that I need to connect to. How do I do this? Not even sure where to start. My url looks like this

https://storage.table.core.windows.net/GlobalTagExport?sv=2019-02-02&spr=https%2Chttp&si=Location&sig=FLIcrZhC%2B0IxJuMgxltPdoRSGvhit7s%3D&tn=GlobalTagExport&srk=LIT1_Display&spk=S265&epk=S265&erk=LIT1_Display

(fake link)

The link is using the Azure REST API to pull the tagValue property from a Table storage entity (essentially an SQL query)

Any help would be much appreciated.

Would this be the WebDev Module?

The link returns an XML value like this

<?xml version="1.0" encoding="utf-8"?>
<feed xml:base=https://storage.table.core.windows.net/ xmlns=http://www.w3.org/2005/Atom xmlns:d=http://schemas.microsoft.com/ado/2007/08/dataservices xmlns:m=http://schemas.microsoft.com/ado/2007/08/dataservices/metadata xmlns:georss=http://www.georss.org/georss xmlns:gml=http://www.opengis.net/gml>
       <id>https://storage.table.core.windows.net/GlobalTagExport</id>
       <title type="text">GlobalTagExport</title>
       <updated>2026-07-23T16:33:56Z</updated>
       <link rel="self" title="GlobalTagExport" href="GlobalTagExport"/>
       <entry m:etag="W/&quot;datetime'2026-07-23T16%3A33%3A05.8189167Z'&quot;">
       <id>https://storage.table.core.windows.net/GlobalTagExport(PartitionKey='S265',RowKey='LIT1_Display')</id>
              <category term="storage.GlobalTagExport" scheme=http://schemas.microsoft.com/ado/2007/08/dataservices/scheme/>
              <link rel="edit" title="GlobalTagExport" href="GlobalTagExport(PartitionKey='S265',RowKey='LIT1_Display')"/>
              <title/>
              <updated>2026-07-23T16:33:56Z</updated>
              <author>
                     <name/>
              </author>
              <content type="application/xml">
                     <m:properties>
                           <d:PartitionKey>S265</d:PartitionKey>
                           <d:RowKey>LIT1_Display</d:RowKey>
                           <d:Timestamp m:type="Edm.DateTime">2026-07-23T16:33:05.8189167Z</d:Timestamp>
                           <d:lastCheckedUtc>2026-07-23T16:33:05.8202368Z</d:lastCheckedUtc>
                           <d:tagValue>15.8</d:tagValue>
                     </m:properties>
              </content>
       </entry>
</feed>
2

You could just use the HTTPClient in a project script to pull the value, parse the returned XML and then write the values to memory tags, a dataset tag, or whatever.

No need for Webdev for this.

3

Never used this either. Care to enlighten me?

4

Some lightly edited Claude output.

According to the robot, if you add an Accept: application/json header you'll get JSON back, instead of XML, which is a lot nicer to parse.

logger = system.util.getLogger('CloudTag')

def fetchCloudTag(row_key, partition_key='S265', timeout=5000):
	"""
	Fetch a single entity's tagValue from the Azure Table Storage export.
	"""
	# Base endpoint (no query string). Everything variable goes in `params`.
	base_url = 'https://storage.table.core.windows.net/GlobalTagExport'

	# The SAS token pieces. In production, use secrets instead of hardcoding
	sas_params = {
		'sv':  '2019-02-02',
		'spr': 'https,http',
		'si':  'Location',
		'sig': 'FLIcrZhC+0IxJuMgxltPdoRSGvhit7s=',
		'tn':  'GlobalTagExport',
	}

	# The "query" portion — which entity you want. These are the bits
	# you'll typically change from call to call.
	query_params = {
		'srk': row_key,          # start row key
		'erk': row_key,          # end row key (same → single row)
		'spk': partition_key,    # start partition key
		'epk': partition_key,    # end partition key
	}

	params = {}
	params.update(sas_params)
	params.update(query_params)

	headers = {
		'Accept': 'application/json;odata=nometadata',
	}

	response = system.net.httpClient.get(base_url, params=params, headers=headers)

	if not response.good:
		logger.warn('HTTP %d fetching %s/%s: %s' % (
			response.statusCode, partition_key, row_key,
			response.text[:200] if response.text else ''))
		return None

	# Azure Table Storage returns {"value": [ {...entity...}, ... ]}
	payload = response.json
	entities = payload.get('value', []) if payload else []
	if not entities:
		logger.info('No entity found for %s/%s' % (partition_key, row_key))
		return None

	entity = entities[0]
	# Adjust the property name to whatever your table actually uses:
	return entity.get('tagValue')

# --- Try it ---
value = fetchCloudTag(row_key='LIT1_Display', partition_key='S265')
print 'Fetched value:', value
5

Thanks Paul. This is what I got to work just in the script console:

url = "..."

client = system.net.httpClient()
# Send a non-blocking request to an endpoint that will wait 3 seconds.
promise = client.getAsync(url, headers={"Accept": "application/json;odata=nometadata"})
# This will print before we get a response from the endpoint.
print "doing something while waiting..."
# do more work here...
# After the work on the previous lines, we can now block and wait for a response.
response = promise.get()
if response.good:
    print response.json['value'][0]['tagValue']