add opc example (#401)

* add example

* remove sub handler

* spellcheck

.wordlist.txt

@@ -363,3 +363,4 @@ crc
 FlowTag
 NoOpFileTagParams
 UnappliedFileTag
+OPC

docs/app/agents/AgentTemplates.mdx

@@ -314,7 +314,7 @@ def execute(**kwargs) -> UploadFileParams | None:
     return None
 ```
 
-Variables can be configured during the installation by [passing additional variables during the installation](../../app/agents/AgentInstall#windows-installation):
+Variables (e.g. - _parent_dir_ and _recency_min_) can be configured during the installation by [passing additional variables during the installation](../../app/agents/AgentInstall#windows-installation):
 
 ```bash
 # example variable configuration at installation
@@ -323,3 +323,114 @@ Variables can be configured during the installation by [passing additional varia
 
 Post-installation, for Agents v4.8+, the parameters for Windows Connections can be [updated in the Connection UI](../../app/agents/AgentMonitoring#monitoring-agent-connections).
 
+### Querying OPC server
+
+The following example demonstrates how to query an OPC server for bioreactor data on a regular cadence, and places the results in Ganymede for querying and visualizing.
+
+```python
+from agent_sdk import FileParam, TriggerFlowParams
+from agent_sdk import info
+import pandas as pd
+
+import asyncio
+from asyncua import Client, Node
+
+import time
+from functools import reduce
+
+OPC_SERVER_URL = "opc.tcp://localhost:4840/ganymede/server/"
+OPC_SERVER_URI = "http://examples.ganymede.github.io"
+
+EXECUTION_TIME = 10  # seconds
+PUBLISHING_INTERVAL = 500  # milliseconds
+SAMPLING_INTERVAL = 2000  # milliseconds
+
+BIOREACTORS = [
+    "Cytiva Wave",
+    "Cytiva XDR",
+]
+
+
+
+
+async def opc_client():
+    client = Client(url=OPC_SERVER_URL)
+    async with client:
+        idx = await client.get_namespace_index(uri=OPC_SERVER_URI)
+        info(f"Namespace index for '{OPC_SERVER_URI}': '{idx}'")
+
+        node_display_names = {}
+        nodes_all = []
+        for bioreactor in BIOREACTORS:
+            object_node = await client.nodes.objects.get_child(f"{idx}:{bioreactor}")
+            nodes = await object_node.get_children()
+
+            for node in nodes:
+                display_name = await node.read_display_name()
+                node_display_names[node] = f"Bioreactor {bioreactor} - {display_name.Text}"
+
+            nodes_all.append(nodes)
+        nodes_all_flattened = reduce(lambda x, y: x + y, nodes_all)
+
+        # manual
+        start_time = time.time()
+        collected_data = []
+
+        while (time.time() - start_time) < EXECUTION_TIME:
+            snapshot = []
+
+            tasks = [node.read_data_value() for node in nodes_all_flattened]
+            data_values = await asyncio.gather(*tasks)
+
+            for node, data_value in zip(nodes_all_flattened, data_values):
+                value = data_value.Value.Value
+                timestamp = data_value.SourceTimestamp
+
+                instrument, sensor_category, sensor_name = [
+                    n.strip() for n in node_display_names[node].split("-")
+                ]
+
+                snapshot.append(
+                    {
+                        "instrument": instrument,
+                        "sensor_category": sensor_category,
+                        "sensor_name": sensor_name,
+                        "value": value,
+                        "timestamp": timestamp,
+                    }
+                )
+
+            collected_data.extend(snapshot)
+            await asyncio.sleep(SAMPLING_INTERVAL / 1000)
+
+        return collected_data
+
+
+# Required Function
+def execute(**kwargs) -> TriggerFlowParams | None:
+    """
+    Function to execute on specified cadence
+
+    Returns
+    -------
+    TriggerFlowParams | None
+        Parameters to use in triggered Flow.  If None is specified, then Flow will not be triggered.
+    """
+
+    collected_data = asyncio.run(opc_client())
+    collected_data_str = pd.DataFrame(collected_data).to_csv(header=True, index=False)
+    info(f"Collected data: {collected_data_str}")
+
+    current_time = int(time.time() * 1000)
+    filename = f"opc_cron{current_time}.txt"
+
+    param = "Ingest_Bioreactor_Snapshot.file_pattern"
+    new_file_param = FileParam(filename=filename, body=collected_data_str, param=param)
+
+    return TriggerFlowParams(
+        single_file_params={param: new_file_param},
+        multi_file_params=None,
+        benchling_tag=None,
+        additional_params=None,
+    )
+```