`open62541-historizing`

A vanilla open62541 v1.4.8 server with HistoryRead and HistoryUpdate enabled on a single Double variable. Its only job is to let a client library exercise the OPC UA HistoryUpdate service set against a conformant implementation — UA-.NETStandard does not implement HistoryUpdate on its demo nodes, so a different server is needed to test the call path end-to-end.

Endpoint

opc.tcp://localhost:24842
security policy: None
security mode:   None
identity:        Anonymous

No discovery URL, no encryption, no auth.

What's in the address space

Exactly one application-namespace node:

The node sits under the standard Objects folder (ns=0;i=85), organised via Organizes (ns=0;i=35), with BaseDataVariableType as its type definition. Initial value is 0.0.

ns=2 resolves to the urn:php-opcua:historizing URI declared by UA_Server_addNamespace at boot. Resolve the namespace index at runtime — open62541 may shift it if other namespaces appear before yours.

Plus the standard server nodes from UA_NAMESPACE_ZERO=FULL (Server, Objects, Types, …).

The history backend

USER update strategy means the server does not sample the node's value on writes — the history is populated exclusively through HistoryUpdate calls from the client. A regular write() to the node updates the live value but does not add a history point.

Restart the container to wipe the backend — there is no persistence.

Supported history operations

The split between "accepted at the wire level" and "actually executes the operation" matters when writing integration tests: the framing checks succeed on every operation, but only the five rows in the top block produce real side-effects on the in-memory buffer.

Why this exists

The OPC UA spec defines HistoryRead and HistoryUpdate as optional service sets. UA-.NETStandard (the reference stack used by uanetstandard-test-suite) implements HistoryRead on its historian nodes but does not expose HistoryUpdate to clients. A client library that ships historyInsert / historyReplace / historyDeleteRawModified needs a server that round-trips those calls end-to-end.

open62541 implements both service sets, and its UA_HistoryDataBackend_Memory plus UA_HISTORIZINGUPDATESTRATEGY_USER combination gives us a clean fixture: the server adds nothing to history on its own, so every sample observable by HistoryReadRaw came from a client HistoryUpdate call we can assert against.

What the entrypoint does

Nothing — the Dockerfile CMD is /usr/local/bin/historizing_server directly. No shell wrapper, no cert generation, no fallback chain (unlike open62541-nm). The binary starts, opens port 4840 inside the container, and runs until SIGINT / SIGTERM.

The container logs two lines on startup:

[historizing] open62541 historizing server starting on :4840
[historizing] exposed node: ns=<urn:php-opcua:historizing>;s=Historizing.Counter (Double, history enabled)

CMake build flags

-DUA_ENABLE_HISTORIZING=ON
-DUA_ENABLE_SUBSCRIPTIONS=ON
-DUA_ENABLE_METHODCALLS=ON
-DUA_NAMESPACE_ZERO=FULL
-DUA_BUILD_EXAMPLES=ON
-DBUILD_SHARED_LIBS=OFF

Notably not built with UA_ENABLE_NODEMANAGEMENT=ON — AddNodes / DeleteNodes calls against this server respond with Bad_ServiceUnsupported. Use open62541-nm for those.

Logs

docker compose logs -f open62541-historizing

open62541's logger is verbose — every HistoryUpdate call logs the operation, the timestamps it touched, and the per-sample status. Useful for confirming that the backend is actually doing what the client thinks it asked for.

Limitations

Typical test pattern

1. setup:     client.connect()
2. arrange:   client.historyUpdate(
                  nodeId: 'ns=2;s=Historizing.Counter',
                  operation: HistoryUpdateType::Insert,
                  samples:   [...timestamped DataValues...],
              )
3. act:       client.historyReadRaw(
                  nodeId: 'ns=2;s=Historizing.Counter',
                  startTime: ..., endTime: ...,
              )
4. assert:    inserted samples appear in the read response
5. cleanup:   restart the container, or HistoryDelete the range
6. teardown:  client.disconnect()

When NOT to use this server

• You need NodeManagement (AddNodes, DeleteNodes) — use open62541-nm (port 24840).
• You need secured connections or non-anonymous identity — use open62541-all-security (port 24841).
• You need rich test data — use uanetstandard-test-suite.

This server is the target for HistoryUpdate testing and not much else.

Where to read next

• open62541-nm — the NodeManagement sibling.
• open62541-all-security — the security-focused sibling.
• Ports and endpoints — the whole port allocation in context.