ExOpcua

Pure Elixir implementation of OPC UA (Unified Architecture) — client and server. Zero native dependencies. Built against OPC UA v1.05.06 specifications with interop testing against open62541.

Features

• Pure Elixir — no NIFs, no ports, no C dependencies
• Client & Server — full session lifecycle on both sides
• 437 generated types — 368 structured + 69 enumerated, compiled from the official BSD schema
• 25 built-in types — spec-compliant binary encoding with property-based tests
• 8 security policies — None, Basic256Sha256, Aes128_Sha256_RsaOaep, Aes256_Sha256_RsaPss, ECC_nistP256, ECC_nistP384, ECC_brainpoolP256r1, ECC_brainpoolP384r1
• PubSub — UADP NetworkMessage encoding/decoding per Part 14 §7.2.2, interop tested over UDP multicast
• Interop tested — Client & server tests against open62541 v1.5.2 (ci_server + custom C client), PubSub interop over UDP

Note: This project was AI-generated by feeding all OPC UA v1.05.06 specification documents into Claude and working through a comprehensive, spec-driven implementation plan. Every feature was implemented TDD against the specifications, with partial interop validation against open62541. Validation is ongoing work. Please refer to the implementation tables below.

Installation

def deps do
  [
    {:ex_opcua, "~> 0.1.0"}
  ]
end

Quick Start

Client

# Connect (unencrypted, anonymous)
{:ok, client} = ExOpcua.Client.Client.connect("opc.tcp://localhost:4840",
  security_policy: :none
)

# Browse the Root node
{:ok, refs} = ExOpcua.Client.Client.browse(client, %ExOpcua.Types.NodeId{
  namespace: 0, type: :numeric, value: 84
})

# Read a value
{:ok, [data_value]} = ExOpcua.Client.Client.read(client, %ExOpcua.Types.NodeId{
  namespace: 0, type: :numeric, value: 2258  # ServerStatus.CurrentTime
})

# Subscriptions
{:ok, mgr} = ExOpcua.Client.Client.start_subscriptions(client)
{:ok, sub_id} = ExOpcua.Client.Client.create_subscription(mgr, subscriber: self())
{:ok, _} = ExOpcua.Client.Client.create_monitored_items(mgr, sub_id, [
  %{node_id: %ExOpcua.Types.NodeId{namespace: 0, type: :numeric, value: 2258}}
])
# Receive: {:data_change, sub_id, handle, %DataValue{}}

ExOpcua.Client.Client.disconnect(client)

Server

# Build address space
as = ExOpcua.AddressSpace.new()
ExOpcua.AddressSpace.add_node(as, ExOpcua.AddressSpace.Node.variable(
  %ExOpcua.Types.NodeId{namespace: 2, type: :numeric, value: 1001},
  {2, "Temperature"},
  value: %ExOpcua.Types.Variant{type: :double, value: 23.5},
  data_type: %ExOpcua.Types.NodeId{namespace: 0, type: :numeric, value: 11},
  access_level: 3
))

# Start listener
{:ok, listener} = ExOpcua.Server.Listener.start_link(
  port: 4840,
  server_config: %{
    application_name: "MyServer",
    application_uri: "urn:my:server",
    product_uri: "urn:my:product",
    endpoint_url: "opc.tcp://localhost:4840",
    security_policies: [:none],
    user_token_policies: [:anonymous]
  },
  address_space: as,
  callback_module: MyCallbacks
)

---

Specification Compliance Tables

Implementation and interop test status for every OPC UA feature area. These tables serve as the project roadmap.

Implementation Legend

Symbol	Meaning
✔️	Complete
🖥️	Client only
🖧	Server only
❌	Not implemented
🚧	Partial / skeleton

Note: For interop, the symbol refers to the Elixir side tested against open62541.

---

Binary Encoding & Transport — Part 6

Spec Ref	Feature	Impl	Interop
§5.1	UA Binary encoding — 25 built-in types	✔️	✔️
§5.2.2	Primitive type encoding (Boolean, integers, float, double)	✔️	✔️
§5.2.4	String / ByteString / XmlElement encoding	✔️	✔️
§5.2.5	DateTime encoding (Windows FILETIME)	✔️	✔️
§5.2.6	Guid encoding	✔️	✔️
§5.2.7	NodeId encoding (TwoByte, FourByte, Numeric, String, Guid, Opaque)	✔️	✔️
§5.2.8	ExpandedNodeId encoding	✔️	✔️
§5.2.9	StatusCode encoding	✔️	✔️
§5.2.10	DiagnosticInfo encoding (recursive nesting)	✔️	✔️
§5.2.11	QualifiedName encoding	✔️	✔️
§5.2.12	LocalizedText encoding	✔️	✔️
§5.2.13	ExtensionObject encoding	✔️	✔️
§5.2.14	Variant encoding (all type IDs)	✔️	✔️
§5.2.15	DataValue encoding	✔️	✔️
§5.2.16	Array encoding (length-prefixed, null)	✔️	✔️
§5.3	Generated StructuredTypes from BSD schema (368 types)	✔️	✔️
§5.3	Generated EnumeratedTypes from BSD schema (69 types)	✔️	✔️
§6.7.1	HEL (Hello) message	✔️	✔️
§6.7.1	ACK (Acknowledge) message	✔️	✔️
§6.7.1	ERR (Error) message	✔️	✔️
§6.7.1	RHE (ReverseHello) message	✔️	✔️
§6.7.2	MessageChunk framing (OPN / MSG / CLO)	✔️	✔️
§6.7.2	Asymmetric security header (OPN)	✔️	✔️
§6.7.2	Symmetric security header (MSG/CLO)	✔️	✔️
§6.7.2	Sequence header (sequence number, request ID)	✔️	✔️
§6.7.3	Chunk splitting (outbound messages exceeding buffer)	✔️	✔️
§6.7.3	Chunk assembly (multi-chunk inbound reassembly)	✔️	✔️
§6.7.3	Abort chunk handling	✔️	✔️
§6.7.1	TCP UA Connection Protocol (active :once, buffered reads)	✔️	✔️

Security — Part 2 §4, Part 6 §6.7.4–6.8, Part 7

Spec Ref	Feature	Impl	Interop
Part 7 §6.2.1	SecurityPolicy#None	✔️	✔️
Part 7 §6.2.5	Basic256Sha256 (RSA-2048, SHA-256, AES-256-CBC)	✔️	✔️
Part 7 §6.2.6	Aes128_Sha256_RsaOaep (RSA-2048, SHA-256, AES-128-CBC)	✔️	✔️
Part 7 §6.2.7	Aes256_Sha256_RsaPss (RSA-2048, SHA-256, AES-256-CBC, PSS)	✔️	✔️
Part 7 §6.2.8	ECC_nistP256 (ECDSA, ECDH, HKDF, AES-128-CBC)	✔️	✔️
Part 7 §6.2.9	ECC_nistP384 (ECDSA, ECDH, HKDF, AES-256-CBC)	✔️	✔️
Part 7 §6.2.10	ECC_brainpoolP256r1 (ECDSA, ECDH, HKDF, AES-128-CBC)	✔️	✔️
Part 7 §6.2.11	ECC_brainpoolP384r1 (ECDSA, ECDH, HKDF, AES-256-CBC)	✔️	✔️
Part 6 §6.1	X.509 v3 certificate generation (RSA 2048–4096, ECC P-256/P-384/brainpool)	✔️	✔️
Part 6 §6.1	Certificate parsing (CN, public key, SAN/ApplicationURI)	✔️	✔️
Part 6 §6.1	Certificate validation (trust chain, expiry)	✔️	✔️
Part 6 §6.1	Certificate thumbprint (SHA-1)	✔️	✔️
Part 6 §6.2.6	Certificate trust list (Agent-based, add/remove/reject)	✔️	✔️
Part 6 §6.2.5	Certificate Revocation List (CRL) checking	✔️	✔️
Part 6 §6.7.5	Asymmetric sign & encrypt (OPN — RSA + ECC sign-only)	✔️	✔️
Part 6 §6.7.5	Symmetric sign & encrypt (MSG/CLO — RSA + ECC encrypt-then-MAC)	✔️	✔️
Part 6 §6.7.5	P_SHA256 symmetric key derivation from nonces	✔️	✔️
Part 6 §6.8.1	HKDF key derivation for ECC (RFC 5869)	✔️	✔️
Part 6 §6.8.1	Per-message IV XOR (ECC profiles only, Table 68)	✔️	✔️
Part 6 §6.7.5	Nonce exchange and validation	✔️	✔️
Part 4 §5.5.2	Token renewal at 75% lifetime	✔️	✔️
Part 6 §6.7.6	Sequence number validation (monotonic + wrap)	✔️	✔️
Part 6 §6.7	RSA PKCS#1 v1.5 signing / verification	✔️	✔️
Part 6 §6.7	RSA-PSS signing (Aes256_Sha256_RsaPss)	✔️	✔️
Part 6 §6.7	RSA-OAEP encryption / decryption (SHA-1, SHA-256)	✔️	✔️
Part 6 §6.7	AES-CBC encryption / decryption (128 & 256 bit)	✔️	✔️
Part 6 §6.7	HMAC-SHA256 signing / verification	✔️	✔️

Authentication — Part 4 §7.36

Spec Ref	Feature	Impl	Interop
Part 4 §7.36.3	AnonymousIdentityToken (encoding ID 321)	✔️	✔️
Part 4 §7.36.4	UserNameIdentityToken (encoding ID 324)	✔️	✔️
Part 4 §7.36.5	X509IdentityToken (encoding ID 327)	✔️	❌
Part 4 §7.36.6	IssuedIdentityToken (Kerberos/JWT)	❌	❌
Part 6 §6.5.2	JSON Web Token (JWT) UserIdentityToken	❌	❌
Part 6 §6.5.3	OAuth2 token flow (authorization code, refresh, client credentials)	❌	❌

Session & Connection — Part 4 §5.5–5.6

Spec Ref	Feature	Impl	Interop
Part 4 §5.5.1	OpenSecureChannel / CloseSecureChannel	✔️	✔️
Part 4 §5.5.2	SecurityToken renewal (OPN with RequestType=Renew)	✔️	🖥️
Part 4 §5.6.2	CreateSession	✔️	✔️
Part 4 §5.6.3	ActivateSession (with identity token)	✔️	✔️
Part 4 §5.6.4	CloseSession	✔️	✔️
Part 4 §5.6.5	Cancel (cancel outstanding requests)	❌	❌
Part 4 §5.6.3	Server signature verification (CreateSession)	✔️	🖥️
Part 4 §5.6.3	Client signature computation (ActivateSession)	✔️	🖥️
—	Session keepalive (periodic ServerStatus read)	✔️	🖥️
—	Auto-reconnect with exponential backoff	✔️	❌
Part 4 §5.6.3	Session activation gating (exempt service IDs)	✔️	🖧
Part 4 §5.5	Secure channel ownership validation	✔️	❌

Discovery Services — Part 4 §5.4, Part 12

Spec Ref	Feature	Impl	Interop
Part 4 §5.4.2	FindServers	✔️	🖥️
Part 4 §5.4.4	GetEndpoints	✔️	✔️
Part 4 §5.4.5	Endpoint filtering by profileUris	✔️	❌
Part 4 §5.4.5	EndpointDescription with UserTokenPolicies	✔️	✔️
Part 12 §5.2	FindServersOnNetwork (mDNS)	❌	❌
Part 12 §5.3	RegisterServer / RegisterServer2	❌	❌
Part 12	Local Discovery Server (LDS)	❌	❌
Part 12	Global Discovery Server (GDS)	🚧	❌
Part 12	GDS Certificate Manager	🚧	❌

Browse Services — Part 4 §5.8

Spec Ref	Feature	Impl	Interop
Part 4 §5.8.2	Browse (forward, inverse, both)	✔️	✔️
Part 4 §5.8.2	Browse with reference type filter	✔️	✔️
Part 4 §5.8.2	Browse with node class filter	✔️	❌
Part 4 §5.8.2	Browse with includeSubtypes	✔️	✔️
Part 4 §5.8.3	BrowseNext (continuation points)	✔️	🖥️
Part 4 §5.8.4	TranslateBrowsePathsToNodeIds	✔️	✔️
Part 4 §5.8.4	Multi-segment relative paths	✔️	🖥️
Part 4 §5.8.5	RegisterNodes	✔️	✔️
Part 4 §5.8.5	UnregisterNodes	✔️	✔️

Attribute Services — Part 4 §5.10

Spec Ref	Feature	Impl	Interop
Part 4 §5.10.2	Read (single node)	✔️	✔️
Part 4 §5.10.2	Read (batch / multi-node)	✔️	🖥️
Part 4 §5.10.2	Read with IndexRange (array subsets)	✔️	🖥️
Part 4 §5.10.2	Read all 25 built-in data types	✔️	🖥️
Part 4 §5.10.2	TimestampsToReturn handling	✔️	❌
Part 4 §5.10.4	Write (single node)	✔️	✔️
Part 4 §5.10.4	Write (batch / multi-node)	✔️	❌
Part 4 §5.10.4	Write access level validation	✔️	🖧
Part 4 §5.10.4	Write type checking	✔️	🖧
Part 4 §5.10.2	Read of nonexistent node → BadNodeIdUnknown	✔️	✔️
Part 4 §5.10.4	Write type mismatch → BadTypeMismatch	✔️	✔️
Part 4 §5.10.4	Write access denied → BadNotWritable	✔️	🖥️

Method Services — Part 4 §5.11

Spec Ref	Feature	Impl	Interop
Part 4 §5.11.2	Call (invoke method on object)	✔️	✔️
Part 4 §5.11.2	Input argument count validation	✔️	🖧
Part 4 §5.11.2	Input argument type checking	✔️	🖧
Part 4 §5.11.2	Output argument wrapping	✔️	✔️
Part 4 §5.11.2	Call nonexistent method → BadMethodInvalid	✔️	🖧
Part 4 §5.11.2	Call with wrong args → BadInvalidArgument	✔️	🖧

Subscription Services — Part 4 §5.13

Spec Ref	Feature	Impl	Interop
Part 4 §5.13.2	CreateSubscription	✔️	✔️
Part 4 §5.13.3	ModifySubscription	✔️	🖥️
Part 4 §5.13.4	SetPublishingMode	✔️	🖥️
Part 4 §5.13.5	Publish (request/response with notifications)	✔️	✔️
Part 4 §5.13.5	Publish — SubscriptionAcknowledgement (sequence tracking)	✔️	❌
Part 4 §5.13.6	Republish	✔️	🖥️
Part 4 §5.13.7	TransferSubscriptions	✔️	❌
Part 4 §5.13.8	DeleteSubscriptions	✔️	✔️
Part 4 Table 84	Publish state machine (Normal/Late/KeepAlive transitions)	✔️	✔️
Part 4 §5.13.5	Publish request queuing (N outstanding)	✔️	✔️
Part 4 §5.13.5	Keep-alive tracking (max keep-alive count)	✔️	✔️
Part 4 §5.13.5	Notification retransmission queue	✔️	❌

Monitored Item Services — Part 4 §5.12

Spec Ref	Feature	Impl	Interop
Part 4 §5.12.2	CreateMonitoredItems	✔️	✔️
Part 4 §5.12.3	ModifyMonitoredItems	✔️	❌
Part 4 §5.12.4	SetMonitoringMode (disabled/sampling/reporting)	✔️	🖥️
Part 4 §5.12.5	SetTriggering (triggering links)	✔️	❌
Part 4 §5.12.6	DeleteMonitoredItems	✔️	🖥️
Part 4 §5.12.2	DataChangeFilter	✔️	❌
Part 4 §5.12.2	EventFilter (select_clauses + ContentFilter where_clause)	✔️	❌
Part 4 §5.12.2	AggregateFilter (windowed sample accumulation)	✔️	❌
Part 4 §5.12.2	Initial value sampling on creation	✔️	❌
—	DataChangeNotification dispatch to subscribers	✔️	🖥️
—	EventNotificationList dispatch	✔️	❌
—	StatusChangeNotification dispatch	✔️	❌
Part 4 §5.12.2	Monitor nonexistent node → BadNodeIdUnknown	✔️	🖧

Node Management Services — Part 4 §5.7

Spec Ref	Feature	Impl	Interop
Part 4 §5.7.2	AddNodes	✔️	❌
Part 4 §5.7.3	AddReferences	✔️	❌
Part 4 §5.7.4	DeleteNodes	✔️	❌
Part 4 §5.7.5	DeleteReferences	✔️	❌

Address Space Model — Part 3, Part 5

Spec Ref	Feature	Impl	Interop
Part 3 §5.2	Object node class	✔️	✔️
Part 3 §5.3	Variable node class	✔️	✔️
Part 3 §5.4	Method node class	✔️	✔️
Part 3 §5.5	ObjectType node class	✔️	❌
Part 3 §5.6	VariableType node class	✔️	❌
Part 3 §5.7	ReferenceType node class (with InverseName)	✔️	✔️
Part 3 §5.8	DataType node class	✔️	❌
Part 3 §5.9	View node class	✔️	❌
Part 5	Standard namespace (ns=0) — Root, Objects, Types, Views, Server	✔️	✔️
Part 5	NodeSet2.xml loading (4MB standard schema)	✔️	❌
Part 5	ETS-backed node store (nodes table + references bag)	✔️	✔️
Part 5	Bidirectional reference storage (auto forward + inverse)	✔️	✔️
Part 5	Multiple namespace support (index-based)	✔️	✔️

Data Access — Part 8

Spec Ref	Feature	Impl	Interop
Part 8 §5.3	DataItemType (Definition, ValuePrecision)	✔️	❌
Part 8 §5.3.2	AnalogItemType (EURange, InstrumentRange, EngineeringUnits)	✔️	❌
Part 8 §5.3.3	DiscreteItemType (TwoState / MultiState)	✔️	❌
Part 8 §5.3.4	ArrayItemType (spectrum/image data)	✔️	❌
Part 8 §5.6.3	EUInformation (engineering units with SI support)	✔️	❌

Alarms & Conditions — Part 9

Spec Ref	Feature	Impl	Interop
Part 9 §5.5	ConditionType (activate, deactivate, acknowledge, confirm)	✔️	❌
Part 9 §5.5	Condition branch support (branch_id, create_branch)	✔️	❌
Part 9 §5.5	Condition retain flag	✔️	❌
Part 9 §5.8.2	ExclusiveLevelAlarm (HighHigh/High/Low/LowLow)	✔️	❌
Part 9 §5.8.3	NonExclusiveLevelAlarm (multiple active states)	✔️	❌
Part 9 §5.8.8	RateOfChangeAlarm (dPV/dt with hysteresis)	✔️	❌
Part 9 §5.8.5	DiscreteAlarm (binary/discrete state changes)	✔️	❌
Part 9 §5.8.10	LatchingAlarm	✔️	❌
Part 9 §5.8	Alarm evaluation engine (value → state transitions)	✔️	❌
Part 9 §5.8.7	ExclusiveDeviationAlarm	❌	❌
Part 9 §5.8.9	NonExclusiveRateOfChangeAlarm	❌	❌
Part 9 §5.6	ShelvedStateMachineType (TimedShelve, OneShotShelve, Unshelve)	❌	❌
Part 9 §5.7	AckedConditionType / ConfirmedConditionType dialogs	❌	❌

Historical Access — Part 11

Spec Ref	Feature	Impl	Interop
Part 11 §6.4	Pluggable HistoryBackend behaviour	✔️	❌
Part 11 §6.4.2	ReadRawModifiedDetails (time-range query)	✔️	❌
Part 11 §6.4.3	ReadProcessedDetails (with AggregateConfiguration)	✔️	❌
Part 11 §6.4.4	ReadAtTimeDetails (values at specific timestamps)	✔️	❌
Part 11 §6.4.5	ReadEventDetails (event history with filter)	✔️	❌
Part 11 §6.4.2	ReadModifiedDetails (modification metadata)	✔️	❌
Part 11 §6.5	HistoryUpdate — Insert	✔️	❌
Part 11 §6.5	HistoryUpdate — Replace	✔️	❌
Part 11 §6.5	HistoryUpdate — Delete (by range / at time)	✔️	❌
Part 11 §6.4	History continuation points	✔️	❌
—	Built-in in-memory / ETS history backend	❌	❌

Aggregates — Part 13

Spec Ref	Feature	Impl	Interop
Part 13 §5.4	Interpolative aggregate	❌	❌
Part 13 §5.4	Average / TimeAverage / TimeAverage2	❌	❌
Part 13 §5.4	Total / TotalizeValue	❌	❌
Part 13 §5.4	Minimum / Maximum / MinimumActualTime / MaximumActualTime	❌	❌
Part 13 §5.4	Range / Count / DurationGood / DurationBad	❌	❌
Part 13 §5.4	NumberOfTransitions / Start / End / Delta / DeltaBounds	❌	❌
Part 13 §5.4	PercentGood / PercentBad / WorstQuality	❌	❌
Part 13 §5.4	StandardDeviationSample / StandardDeviationPopulation / Variance	❌	❌
Part 13 §5.4	RegSlope / RegConst / RegDeviation / RegStdDev	❌	❌
Part 13 §5.3	AggregateConfiguration (stepping, percentDataBad, etc.)	🚧	❌

PubSub — Part 14

Spec Ref	Feature	Impl	Interop
Part 14 §7.2.2	UADP NetworkMessage encoding/decoding	✔️	✔️
Part 14 §7.2.2	UADP GroupHeader (all optional fields)	✔️	✔️
Part 14 §7.2.2	UADP DataSetMessage (KeyFrame/DeltaFrame/Event)	✔️	✔️
Part 14 §7.2.2	UADP ExtendedFlags1/2 (Timestamp, PicoSeconds)	✔️	✔️
Part 14 §7.2.2	UADP PayloadHeader (DataSetWriterIds)	✔️	✔️
Part 14 §7.2.2	UADP PublisherId (Byte/UInt16/UInt32/UInt64/String)	✔️	✔️
Part 14 §7.2.2	UADP field encodings (Variant/RawData/DataValue)	✔️	✔️
Part 14 §7.3	JSON NetworkMessage encoding	❌	❌
Part 14 §8.2	UDP multicast transport (UADP over UDP)	✔️	✔️
Part 14 §8.3	MQTT transport	🚧	❌
Part 14 §8.4	AMQP transport	❌	❌
Part 14 §6.2	PublishedDataSet / DataSetWriter	✔️	✔️
Part 14 §6.2	DataSetReader / SubscribedDataSet	✔️	✔️
Part 14 §6.2	WriterGroup / ReaderGroup	✔️	✔️
Part 14 §6.2	PubSubConnection management	❌	❌
Part 14 §7.2.2	UADP message security (signing/encryption)	❌	❌
Part 14 §7.2.2	UADP publisher/subscriber key exchange	❌	❌
Part 14 §6.4	DataSetMetaData management	❌	❌
Part 14 §6.2.9	PubSub diagnostics	❌	❌

Query Services — Part 4 §5.9

Spec Ref	Feature	Impl	Interop
Part 4 §5.9.2	QueryFirst	❌	❌
Part 4 §5.9.3	QueryNext	❌	❌

Server Features

Spec Ref	Feature	Impl	Interop
—	ThousandIsland TCP listener	✔️	✔️
—	Per-connection :gen_statem handler	✔️	✔️
—	Service dispatcher with session gating	✔️	🖧
—	ETS-backed session manager (create/activate/expire)	✔️	✔️
—	Subscription engine (pure data structure)	✔️	🖧
—	Pluggable callback behaviour (handle_call, etc.)	✔️	🖧
—	Dynamic port binding (port 0)	✔️	✔️
Part 4 §5.6.2	Server nonce generation	✔️	🖧
Part 4 §5.6.2	Server endpoints in CreateSession response	✔️	🖧

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Interop Test Summary

All interop tests run against open62541 v1.5.2 (OPC Foundation certified). Requires Docker.

Suite	Tests	Description
Client vs ci_server	30	Our client against open62541's example server (incl. encrypted + username auth)
interop_client vs our server	1 (21 checks)	open62541's C client exercises all services against our server
Encrypted client vs our server	1 (21 checks)	open62541's C client with Basic256Sha256 against our server (asymmetric header)
Self-interop publish	5	Our client vs our server — publish state machine (Part 4, Table 79)
Self-interop ECC	4	Our client vs our server — ECC_nistP256 and ECC_nistP384 (connect, read, write, browse)
Security self-interop	14	Aes128/Aes256_RsaPss/brainpool policies, trust list, CRL, token renewal, cert features
Security vs open62541	5	Aes128 + Aes256_RsaPss against ci_server, cert parsing, token renewal over encrypted
open62541 vs server (Aes128/PSS)	2 (21 checks)	open62541 client with Aes128_Sha256_RsaOaep and Aes256_Sha256_RsaPss against our server
Transport self-interop	10	ERR, RHE, abort chunks, chunk splitting/assembly, Guid, DiagnosticInfo
Transport vs open62541	4	ERR handling and large responses against open62541 ci_server
PubSub interop	3	UADP encode/decode over UDP multicast against open62541 publisher/subscriber

# Build the interop Docker image
docker build -t ex_opcua_interop -f test/interop/Dockerfile.open62541 test/interop/

# Run all tests including interop
mix test --include interop

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Architecture

• State machines: Raw :gen_statem (no wrapper libraries)
• Storage: ETS for address space, sessions, subscriptions
• Encoding: All types return iodata (encode) and {:ok, value, rest} (decode)
• Error handling: {:ok, result} / {:error, reason} tuples; batch ops have per-item StatusCode
• Dependencies: Minimal — only ThousandIsland (TCP server)
• Code generation: 437 type modules generated at compile time from the official OPC Foundation BSD schema

Spec References

All implementation targets OPC UA v1.05.06:

Document	Content
Part 1	Overview and Concepts
Part 2	Security Model
Part 3	Address Space Model
Part 4	Services
Part 5	Information Model
Part 6	Mappings (binary encoding, transport, security)
Part 7	Profiles (security policies, conformance units)
Part 8	Data Access
Part 9	Alarms and Conditions
Part 10	Programs
Part 11	Historical Access
Part 12	Discovery and Global Services
Part 13	Aggregates
Part 14	PubSub