Examples

The examples directory of the repository has one runnable program per task. Each runs a server and its clients in one process, uses a temporary PKI directory with freshly generated certificates, ends by itself and prints OK <name>; the test suite runs all of them, so they match the current API. Run one from a checkout:

uv run python examples/01_secure_pair.py

07_instrument_server.py also needs the NodeSet files of the nodeset submodule: git submodule update --init nodeset.

Getting started

01_secure_pair.py

A secure server and client with Server.quickstart and Client.quickstart. Each side creates a PKI directory with a self-signed certificate, and each puts the other’s certificate into its trusted/certs folder, the one step that nothing does automatically.

02_users_and_roles.py

A users file with salted password hashes and three clients: anonymous (read only), a user (may also write and call methods) and an admin (may also change the address space). A refused request comes back as BadUserAccessDenied.

11_sync.py

The same server and client without async and await, through enginir_opcua.sync, with a subscription handler that runs on a handler thread.

15_development_profile.py

The development profile: no security and loopback addresses only, for experiments on your own machine. It is the only example without encryption besides the legacy one.

17_legacy_profile.py

The legacy profile for old devices: a server that offers every policy, a client with security = "auto" that takes the strongest one, a client that names a deprecated policy and a client without security. Every weaker choice is logged as a warning.

Reading, writing and calling

03_read_write_subscribe.py

read_value and write_value, a data-change subscription with a handler, and a client with auto_reconnect=True whose session and subscription come back after the server restarts.

04_methods.py

A method with typed, named arguments declared with ua.Argument. The client reads the declaration, calls the method and handles a refused call.

05_custom_types.py

Enumerations and structures added at runtime with new_enum and new_struct, a variable that holds a structure, and a client that loads the type definitions from the server and decodes the values.

Events, alarms and history

06_events_and_history.py

A custom event type and its generator, a client that subscribes to the events, and the history of a variable and of the events, read back by the client.

12_alarms.py

An exclusive level alarm created with Server.create_condition and driven by update_value, and a client that tracks the current alarms with ConditionTracker and acknowledges them.

Information models and files

07_instrument_server.py

The DI and ADI companion specifications imported from NodeSet2 files, a SpectrometerDeviceType instance with its identification, spectral range and a spectrum, browsed and read by a client.

08_file_transfer.py

Server.add_file for a file on disk and an in-memory file, Server.add_directory for a directory tree, and a client that reads, writes, creates and deletes files with UaFile and UaDirectory.

Operations

09_ha_client.py

Two servers with warm redundancy and an HaClient that keeps its subscription on the healthy one and fails over when the first server reports a low ServiceLevel.

13_diagnostics.py

The standard diagnostics nodes below Server/ServerDiagnostics: the summary counters, the per-session and per-subscription arrays, and the security diagnostics that need the SecurityAdmin role.

14_certificate_management.py

Certificate management over OPC UA with Server.enable_push_management: a client is rejected, and a SecurityAdmin reads the rejected list and trusts its certificate remotely.

16_reverse_connect.py

Reverse connect for a server behind a firewall: the server dials out with add_reverse_connect, and the client waits for it with listen_reverse.

PubSub

10_pubsub.py

A publisher and a subscriber over UDP on the loopback interface: a published data set, a writer group that sends UADP messages and a reader whose sink receives the fields. PubSub is experimental and has no message security; see PubSub (experimental).