Common Definitions

Common definitions for Client, Server and PubSub.

Attribute Id

Every node in an OPC UA information model contains attributes depending on the node type. Possible attributes are as follows:

typedef enum {
    UA_ATTRIBUTEID_INVALID                 = 0,
    UA_ATTRIBUTEID_NODEID                  = 1,
    UA_ATTRIBUTEID_NODECLASS               = 2,
    UA_ATTRIBUTEID_BROWSENAME              = 3,
    UA_ATTRIBUTEID_DISPLAYNAME             = 4,
    UA_ATTRIBUTEID_DESCRIPTION             = 5,
    UA_ATTRIBUTEID_WRITEMASK               = 6,
    UA_ATTRIBUTEID_USERWRITEMASK           = 7,
    UA_ATTRIBUTEID_ISABSTRACT              = 8,
    UA_ATTRIBUTEID_SYMMETRIC               = 9,
    UA_ATTRIBUTEID_INVERSENAME             = 10,
    UA_ATTRIBUTEID_CONTAINSNOLOOPS         = 11,
    UA_ATTRIBUTEID_EVENTNOTIFIER           = 12,
    UA_ATTRIBUTEID_VALUE                   = 13,
    UA_ATTRIBUTEID_DATATYPE                = 14,
    UA_ATTRIBUTEID_VALUERANK               = 15,
    UA_ATTRIBUTEID_ARRAYDIMENSIONS         = 16,
    UA_ATTRIBUTEID_ACCESSLEVEL             = 17,
    UA_ATTRIBUTEID_USERACCESSLEVEL         = 18,
    UA_ATTRIBUTEID_MINIMUMSAMPLINGINTERVAL = 19,
    UA_ATTRIBUTEID_HISTORIZING             = 20,
    UA_ATTRIBUTEID_EXECUTABLE              = 21,
    UA_ATTRIBUTEID_USEREXECUTABLE          = 22,
    UA_ATTRIBUTEID_DATATYPEDEFINITION      = 23,
    UA_ATTRIBUTEID_ROLEPERMISSIONS         = 24,
    UA_ATTRIBUTEID_USERROLEPERMISSIONS     = 25,
    UA_ATTRIBUTEID_ACCESSRESTRICTIONS      = 26,
    UA_ATTRIBUTEID_ACCESSLEVELEX           = 27
} UA_AttributeId;

Returns a readable attribute name like “NodeId” or “Invalid” if the attribute does not exist.

const char *
UA_AttributeId_name(UA_AttributeId attrId);

Access Level Masks

The access level to a node is given by the following constants that are ANDed with the overall access level.

#define UA_ACCESSLEVELMASK_READ           (0x01u << 0u)
#define UA_ACCESSLEVELMASK_CURRENTREAD    (0x01u << 0u)
#define UA_ACCESSLEVELMASK_WRITE          (0x01u << 1u)
#define UA_ACCESSLEVELMASK_CURRENTWRITE   (0x01u << 1u)
#define UA_ACCESSLEVELMASK_HISTORYREAD    (0x01u << 2u)
#define UA_ACCESSLEVELMASK_HISTORYWRITE   (0x01u << 3u)
#define UA_ACCESSLEVELMASK_SEMANTICCHANGE (0x01u << 4u)
#define UA_ACCESSLEVELMASK_STATUSWRITE    (0x01u << 5u)
#define UA_ACCESSLEVELMASK_TIMESTAMPWRITE (0x01u << 6u)

Write Masks

The write mask and user write mask is given by the following constants that are ANDed for the overall write mask. Part 3: 5.2.7 Table 2

#define UA_WRITEMASK_ACCESSLEVEL             (0x01u << 0u)
#define UA_WRITEMASK_ARRAYDIMENSIONS         (0x01u << 1u)
#define UA_WRITEMASK_ARRRAYDIMENSIONS        UA_WRITEMASK_ARRAYDIMENSIONS /* legacy typo alias */
#define UA_WRITEMASK_BROWSENAME              (0x01u << 2u)
#define UA_WRITEMASK_CONTAINSNOLOOPS         (0x01u << 3u)
#define UA_WRITEMASK_DATATYPE                (0x01u << 4u)
#define UA_WRITEMASK_DESCRIPTION             (0x01u << 5u)
#define UA_WRITEMASK_DISPLAYNAME             (0x01u << 6u)
#define UA_WRITEMASK_EVENTNOTIFIER           (0x01u << 7u)
#define UA_WRITEMASK_EXECUTABLE              (0x01u << 8u)
#define UA_WRITEMASK_HISTORIZING             (0x01u << 9u)
#define UA_WRITEMASK_INVERSENAME             (0x01u << 10u)
#define UA_WRITEMASK_ISABSTRACT              (0x01u << 11u)
#define UA_WRITEMASK_MINIMUMSAMPLINGINTERVAL (0x01u << 12u)
#define UA_WRITEMASK_NODECLASS               (0x01u << 13u)
#define UA_WRITEMASK_NODEID                  (0x01u << 14u)
#define UA_WRITEMASK_SYMMETRIC               (0x01u << 15u)
#define UA_WRITEMASK_USERACCESSLEVEL         (0x01u << 16u)
#define UA_WRITEMASK_USEREXECUTABLE          (0x01u << 17u)
#define UA_WRITEMASK_USERWRITEMASK           (0x01u << 18u)
#define UA_WRITEMASK_VALUERANK               (0x01u << 19u)
#define UA_WRITEMASK_WRITEMASK               (0x01u << 20u)
#define UA_WRITEMASK_VALUEFORVARIABLETYPE    (0x01u << 21u)
#define UA_WRITEMASK_DATATYPEDEFINITION      (0x01u << 22u)
#define UA_WRITEMASK_ROLEPERMISSIONS         (0x01u << 23u)
#define UA_WRITEMASK_ACCESSRESTRICTIONS      (0x01u << 24u)
#define UA_WRITEMASK_ACCESSLEVELEX           (0x01u << 25u)

ValueRank

The following are the most common ValueRanks used for Variables, VariableTypes and method arguments. ValueRanks higher than 3 are valid as well (but less common).

#define UA_VALUERANK_SCALAR_OR_ONE_DIMENSION  -3
#define UA_VALUERANK_ANY                      -2
#define UA_VALUERANK_SCALAR                   -1
#define UA_VALUERANK_ONE_OR_MORE_DIMENSIONS    0
#define UA_VALUERANK_ONE_DIMENSION             1
#define UA_VALUERANK_TWO_DIMENSIONS            2
#define UA_VALUERANK_THREE_DIMENSIONS          3

EventNotifier

The following are the available EventNotifier used for Nodes. The EventNotifier Attribute is used to indicate if the Node can be used to subscribe to Events or to read / write historic Events. Part 3: 5.4 Table 10

#define UA_EVENTNOTIFIER_SUBSCRIBE_TO_EVENT (0x01u << 0u)
#define UA_EVENTNOTIFIER_HISTORY_READ       (0x01u << 2u)
#define UA_EVENTNOTIFIER_HISTORY_WRITE      (0x01u << 3u)

Rule Handling

The RuleHanding settings define how error cases that result from rules in the OPC UA specification shall be handled. The rule handling can be softened, e.g. to workaround misbehaving implementations or to mitigate the impact of additional rules that are introduced in later versions of the OPC UA specification.

typedef enum {
    UA_RULEHANDLING_DEFAULT = 0,
    UA_RULEHANDLING_ABORT,  /* Abort the operation and return an error code */
    UA_RULEHANDLING_WARN,   /* Print a message in the logs and continue */
    UA_RULEHANDLING_ACCEPT, /* Continue and disregard the broken rule */
} UA_RuleHandling;

Order

The Order enum is used to establish an absolute ordering between elements.

typedef enum {
    UA_ORDER_LESS = -1,
    UA_ORDER_EQ = 0,
    UA_ORDER_MORE = 1
} UA_Order;

Application Notification

The ApplicationNotification mechanism is for runtime notifications where the server/client wants to make the local application aware of state changes and internal events.

The identifier for the different notifications is a UA_UInt64 integer. The high 32bits contain a bitfield for the notification type. The low 32bits are for detailed differentiation within each type. This allows for easy filtering with bitwise operations.

The notifications comes with a key-value map for the payload. Future additional payload members are added to the end of the payload. So that the names, type and also index of the payload members is stable.

typedef uint64_t UA_ApplicationNotificationType;

/* Lifecycle notifications, no payload */
#define UA_APPLICATIONNOTIFICATIONTYPE_LIFECYCLE          \
    (0x01ULL << 32)
#define UA_APPLICATIONNOTIFICATIONTYPE_LIFECYCLE_STARTED  \
    ((0x01ULL << 32) | 0x01)
#define UA_APPLICATIONNOTIFICATIONTYPE_LIFECYCLE_SHUTDOWN \
    ((0x01ULL << 32) | 0x02)
#define UA_APPLICATIONNOTIFICATIONTYPE_LIFECYCLE_STOPPING \
    ((0x01ULL << 32) | 0x03)
#define UA_APPLICATIONNOTIFICATIONTYPE_LIFECYCLE_STOPPED  \
    ((0x01ULL << 32) | 0x04)

(Server only) Give background information after a SecureChannel is opened or closed.

0:securechannel-id [UInt32]: Identifier of the SecureChannel to which the Session is connected.
0:connection-manager-name [String]: Name of the ConnectionManager (configured in the EventLoop) from which the connction was opened.
0:connection-id [UInt64]: Identifier of the connection in the context of the EventLoop. This is often the socket identifier, but that is not necessarily the case.
0:remote-address [String]: Address (hostname or IP that opened the SecureChannel.
0:protocol-version [UInt32]: The version of the UACP protocol requested by the Client.
0:recv-buffer-size [UInt32]: The largest buffer (chunk size) we can receive over the channel.
0:recv-max-message-size [UInt32]: The maximum size of received messages.
0:recv-max-chunk-count [UInt32]: The maximum number of chunks for received messages.
0:send-buffer-size [UInt32]: The largest buffer (chunk size) we can send over the channel.
0:send-max-message-size [UInt32]: The maximum size of sent messages.
0:send-max-chunk-count [UInt32]: The maximum number of chunks for sent messages.
0:endpoint-url: The target EndpointUri (for the server) indicated by the client.
0:security-mode [MessageSecurityMode]: The SecurityChannel can be unsigned, signed or signed+encrypted.
0:security-policy-uri [String]: Uri of the SecurityPolicy for this SecyrityChannel.
0:certificate-type-id [NodeId]: Certificate type used by the SecurityPolicy for this SecureChannel.
0:remote-certificate [ByteString]: Certificate used by the remote side during OpenSecureChannel.

#define UA_APPLICATIONNOTIFICATIONTYPE_SECURECHANNEL        \
    (0x02ULL << 32)
#define UA_APPLICATIONNOTIFICATIONTYPE_SECURECHANNEL_OPENED \
    ((0x02ULL << 32) | 0x01)
#define UA_APPLICATIONNOTIFICATIONTYPE_SECURECHANNEL_CLOSED \
    ((0x02ULL << 32) | 0x02)

(Server only) Give background information for Sessions. The _DEACTIVATE notification occurs when a Sesssion is unbound from its original SecureChannel. Either because the SecureChannel is closed or because the session is activated on another SecureChannel.

0:session-id [NodeId]: Identifier of the Session.
0:securechannel-id [UInt32]: Identifier of the SecureChannel on which the Session is activated. Zero if the Session is not bound to any SecureChannel.
0:session-name [String]: Name of the Session as defined by the client.
0:client-description [ApplicationDescription]: Name of the Session as defined by the client.
0:client-user-id [String]: User identifier used to activate the session. This is extracted from the UserIdentityToken (e.g. username but not the password).
0:locale-ids [Array of String]: List of preferred languages.

Any additional attributes set via UA_Server_setSessionAttribute are appended to the above list.

#define UA_APPLICATIONNOTIFICATIONTYPE_SESSION             \
    (0x04ULL << 32)
#define UA_APPLICATIONNOTIFICATIONTYPE_SESSION_CREATED     \
    ((0x04ULL << 32) | 0x01)
#define UA_APPLICATIONNOTIFICATIONTYPE_SESSION_ACTIVATED   \
    ((0x04ULL << 32) | 0x02)
#define UA_APPLICATIONNOTIFICATIONTYPE_SESSION_DEACTIVATED \
    ((0x04ULL << 32) | 0x03)
#define UA_APPLICATIONNOTIFICATIONTYPE_SESSION_CLOSED      \
    ((0x04ULL << 32) | 0x04)

Processing of a service request or response. The server-side processing of a request can be asynchronous. The existence of a yet-unfinished async operation from the request is signaled with the _SERVICE_ASYNC enum. The _SERVICE_END enum is signalled eventually, once all async operations from the service request are completed.

0:securechannel-id [UInt32]: Identifier of the SecureChannel to which the Session is connected.
0:session-id [NodeId]: Identifier of the Session for/from which the Service is requested. This is the ns=0;i=0 NodeId if no Session is bound to the receiving SecureChannel.
0:request-id [UInt32]: Request/Response correlation identifier. On the server this is zero for transports that do not carry a RequestId.
0:service-type [NodeId]: DataType identifier for the Request (server) or Response (client).

#define UA_APPLICATIONNOTIFICATIONTYPE_SERVICE       \
    (0x08ULL << 32)
#define UA_APPLICATIONNOTIFICATIONTYPE_SERVICE_BEGIN \
    ((0x08ULL << 32) | 0x01)
#define UA_APPLICATIONNOTIFICATIONTYPE_SERVICE_ASYNC \
    ((0x08ULL << 32) | 0x02)
#define UA_APPLICATIONNOTIFICATIONTYPE_SERVICE_END   \
    ((0x08ULL << 32) | 0x03)

(Server only) Signals the creation or modification of a Subscription.

0:session-id [NodeId]: Identifier of the Session for which the Subscription is created. If the subscription is not bound to any Session, then the NodeId ns=0;i=0 is returned.
0:subscription-id [UInt32]: Identifier of the Subscription (unique for the Session).
0:publishing-interval [Double]: Frequence at which accumulated notifications are sent out.
0:lifetime-count [UInt32]: Number of consecutive publishing interval with a missing PublishRequest before the Subscription is starved (deleted).
0:max-keepalive-count [UInt32]: Number of consecutive publishing intervals without a PublishResponse before a keepalive is sent.
0:max-notifications-per-publish [UInt32]: Number of notifications that can be in a PublishResponse.
0:priority [Byte]: Higher-priority subscriptions send out PublishResponses first.
0:publishing-enabled [Boolean]: What the name says.

#define UA_APPLICATIONNOTIFICATIONTYPE_SUBSCRIPTION                \
    (0x10ULL << 32)
#define UA_APPLICATIONNOTIFICATIONTYPE_SUBSCRIPTION_CREATED        \
    ((0x10ULL << 32) | 0x01)
#define UA_APPLICATIONNOTIFICATIONTYPE_SUBSCRIPTION_MODIFIED       \
    ((0x10ULL << 32) | 0x02)
#define UA_APPLICATIONNOTIFICATIONTYPE_SUBSCRIPTION_PUBLISHINGMODE \
    ((0x10ULL << 32) | 0x03)
#define UA_APPLICATIONNOTIFICATIONTYPE_SUBSCRIPTION_TRANSFERRED    \
    ((0x10ULL << 32) | 0x04)
#define UA_APPLICATIONNOTIFICATIONTYPE_SUBSCRIPTION_DELETED        \
    ((0x10ULL << 32) | 0x05)

(Server only) Signals the creation or modification of a MonitoredItem.

0:session-id [NodeId]: Identifier of the Session for which the Subscription is created. If the subscription is not bound to any Session, then the NodeId ns=0;i=0 is returned.
0:subscription-id [UInt32]: Identifier of the Subscription (unique for the Session).
0:monitoreditem-id [UInt32]: Identifier of the MonitoredItem (unique for the Subscription).
0:target-node [NodeId]: Identifier of the Node that is monitored.
0:attribute-id [UInt32]: Node-attribute that is being monitored. Conforms to the values from the UA_AttributeId enum.
0:index-range [String]: Defines if only part of an array value is monitored.
0:timestamps-to-return [TimestampsToReturn]: Enum with the options SOURCE | SERVER | BOTH | NEITHER.
0:monitorimg-mode [MonitoringMode]: Enum with the options DISABLED | SAMPLING | REPORTING.
0:client-handle [UInt32]: Client-supplied identifier of the MonitoredItem.
0:samping-interval [Double]: Interval to evaluate the MonitoredItem in milliseconds.
0:filter [Empty | DataChangeFilter | EventFilter | AggregateFilter]: The filter used to emit notifications.
0:queue-size [UInt32]: Maximum number of notifications waiting to be published.
0:discard-oldest [Boolean]: When the queue overflows, delete the newest or the oldest notification.

#define UA_APPLICATIONNOTIFICATIONTYPE_MONITOREDITEM                \
    (0x20ULL << 32)
#define UA_APPLICATIONNOTIFICATIONTYPE_MONITOREDITEM_CREATED        \
    ((0x20ULL << 32) | 0x01)
#define UA_APPLICATIONNOTIFICATIONTYPE_MONITOREDITEM_MODIFIED       \
    ((0x20ULL << 32) | 0x02)
#define UA_APPLICATIONNOTIFICATIONTYPE_MONITOREDITEM_MONITORINGMODE \
    ((0x20ULL << 32) | 0x03)
#define UA_APPLICATIONNOTIFICATIONTYPE_MONITOREDITEM_DELETED        \
    ((0x20ULL << 32) | 0x04)

(Server only) Signals the creation of an audit event.

The key-value map for audit application notifications follows the properties defined for the AuditEventType and its subtypes. The key-string is the human-readable encoding for the SimpleAttributeOperand of the event properties (value attribute only). The properties should be looked up from their string-key and not via their order-index in the key-value map.

Examples properties are (datatype in brackets):

/ActionTimeStamp [DateTime]
/Status

[Boolean]
/ServerId

[String]

See the definition of the AuditEventType and its subtypes in part 5 of the OPC UA specification. Below follows the hierarchy of the event types. Properties from the super-type are inherited.

AuditEventType
- AuditSecurityEventType
  - AuditChannelEventType
    - AuditOpenSecureChannelEventType
  - AuditSessionEventType
    - AuditCreateSessionEventType
    - AuditActivateSessionEventType
    - AuditCancelEventType
  - AuditCertificateEventType
    - AuditCertificateDataMismatchEventType
    - AuditCertificateExpiredEventType
    - AuditCertificateInvalidEventType
    - AuditCertificateUntrustedEventType
    - AuditCertificateRevokedEventType
    - AuditCertificateMismatchEventType
- AuditNodeManagementEventType
  - AuditAddNodesEventType
  - AuditDeleteNodesEventType
  - AuditAddReferencesEventType
  - AuditDeleteReferencesEventType
- AuditUpdateEventType
  - AuditWriteUpdateEventType
  - AuditHistoryUpdateEventType
- AuditUpdateMethodEventType
- AuditClientEventType
  - AuditClientUpdateMethodResultEventType

#define UA_APPLICATIONNOTIFICATIONTYPE_AUDIT                                   \
    (0x40ULL << 32)
#define UA_APPLICATIONNOTIFICATIONTYPE_AUDIT_SECURITY                          \
    ((0x40ULL << 32) | (0x01 << 16))
#define UA_APPLICATIONNOTIFICATIONTYPE_AUDIT_SECURITY_CHANNEL                  \
    ((0x40ULL << 32) | (0x01 << 16) | (0x01 << 8))
#define UA_APPLICATIONNOTIFICATIONTYPE_AUDIT_SECURITY_CHANNEL_OPEN             \
    ((0x40ULL << 32) | (0x01 << 16) | (0x01 << 8) | 0x01)
#define UA_APPLICATIONNOTIFICATIONTYPE_AUDIT_SECURITY_SESSION                  \
    ((0x40ULL << 32) | (0x01 << 16) | (0x02 << 8))
#define UA_APPLICATIONNOTIFICATIONTYPE_AUDIT_SECURITY_SESSION_CREATE           \
    ((0x40ULL << 32) | (0x01 << 16) | (0x02 << 8) | 0x01)
#define UA_APPLICATIONNOTIFICATIONTYPE_AUDIT_SECURITY_SESSION_ACTIVATE         \
    ((0x40ULL << 32) | (0x01 << 16) | (0x02 << 8) | 0x02)
#define UA_APPLICATIONNOTIFICATIONTYPE_AUDIT_SECURITY_SESSION_CANCEL           \
    ((0x40ULL << 32) | (0x01 << 16) | (0x02 << 8) | 0x03)
#define UA_APPLICATIONNOTIFICATIONTYPE_AUDIT_SECURITY_CERTIFICATE              \
    ((0x40ULL << 32) | (0x01 << 16) | (0x04 << 8))
#define UA_APPLICATIONNOTIFICATIONTYPE_AUDIT_SECURITY_CERTIFICATE_DATAMISMATCH \
    ((0x40ULL << 32) | (0x01 << 16) | (0x04 << 8) | 0x01)
#define UA_APPLICATIONNOTIFICATIONTYPE_AUDIT_SECURITY_CERTIFICATE_EXPIRED      \
    ((0x40ULL << 32) | (0x01 << 16) | (0x04 << 8) | 0x02)
#define UA_APPLICATIONNOTIFICATIONTYPE_AUDIT_SECURITY_CERTIFICATE_INVALID      \
    ((0x40ULL << 32) | (0x01 << 16) | (0x04 << 8) | 0x03)
#define UA_APPLICATIONNOTIFICATIONTYPE_AUDIT_SECURITY_CERTIFICATE_UNTRUSTED    \
    ((0x40ULL << 32) | (0x01 << 16) | (0x04 << 8) | 0x04)
#define UA_APPLICATIONNOTIFICATIONTYPE_AUDIT_SECURITY_CERTIFICATE_REVOKED      \
    ((0x40ULL << 32) | (0x01 << 16) | (0x04 << 8) | 0x05)
#define UA_APPLICATIONNOTIFICATIONTYPE_AUDIT_SECURITY_CERTIFICATE_MISMATCH     \
    ((0x40ULL << 32) | (0x01 << 16) | (0x04 << 8) | 0x06)
#define UA_APPLICATIONNOTIFICATIONTYPE_AUDIT_NODE                              \
    ((0x40ULL << 32) | (0x02 << 16))
#define UA_APPLICATIONNOTIFICATIONTYPE_AUDIT_NODE_ADD                          \
    ((0x40ULL << 32) | (0x02 << 16) | 0x01)
#define UA_APPLICATIONNOTIFICATIONTYPE_AUDIT_NODE_DELETE                       \
    ((0x40ULL << 32) | (0x02 << 16) | 0x02)
#define UA_APPLICATIONNOTIFICATIONTYPE_AUDIT_NODE_ADDREFERENCES                \
    ((0x40ULL << 32) | (0x02 << 16) | 0x03)
#define UA_APPLICATIONNOTIFICATIONTYPE_AUDIT_NODE_DELETEREFERENCES             \
    ((0x40ULL << 32) | (0x02 << 16) | 0x04)
#define UA_APPLICATIONNOTIFICATIONTYPE_AUDIT_UPDATE                            \
    ((0x40ULL << 32) | (0x04 << 16))
#define UA_APPLICATIONNOTIFICATIONTYPE_AUDIT_UPDATE_WRITE                      \
    ((0x40ULL << 32) | (0x04 << 16) | 0x01)
#define UA_APPLICATIONNOTIFICATIONTYPE_AUDIT_UPDATE_HISTORY                    \
    ((0x40ULL << 32) | (0x04 << 16) | 0x02)
#define UA_APPLICATIONNOTIFICATIONTYPE_AUDIT_UPDATE_METHOD                     \
    ((0x40ULL << 32) | (0x04 << 16) | 0x03)
#define UA_APPLICATIONNOTIFICATIONTYPE_AUDIT_CLIENT                            \
    ((0x40ULL << 32) | (0x08 << 16))
#define UA_APPLICATIONNOTIFICATIONTYPE_AUDIT_CLIENT_UPDATEMETHOD               \
    ((0x40ULL << 32) | (0x08 << 16) | 0x01)

(Server only) Signals for the Discovery service set.

We uniquely identify servers by the combination of the following information. This is used to decide whether to update an existing record or whether to create a new one.

For FindServers: ServerUri + one matching DiscoveryUrl
For FindServerOnNetwork: ServerName + DiscoveryUrl

#define UA_APPLICATIONNOTIFICATIONTYPE_DISCOVERY (0x80ULL << 32)

/* A server was added via the RegisterServer service or the local API.
 * Updates and removals are also notified.
 *
 * 0:registered-server [RegisteredServer]
 *    Received server information.
 * 0:discovery-configuration [Array of ExtensionObject]
 *    Additional data, typically a UA_MdnsDiscoveryConfiguration.
 * 0:server-added [Boolean]
 *    They entry was newly added.
 * 0:server-updated [Boolean]
 *    An existing entry was updated.
 * 0:server-removed [Boolean]
 *    The entry was removed.
 * 0:securechannel-id [UInt32]
 *    Identifier of the SecureChannel from which the information was
 *    recieved (0 for locally triggered operations).
 * 0:session-id [NodeId]
 *    Identifier of the Session that called the RegisterServer service.
 *    The Null-NodeId if a SecureChannel without Session made the call. */
#define UA_APPLICATIONNOTIFICATIONTYPE_DISCOVERY_REGISTERSERVER \
    ((0x80ULL << 32) | 0x01)

/* Information about a server over multicast DNS or the local API.
 * Updates over time and removal is also notified (e.g after the DNS
 * TTL (time-to-live) runs out).
 *
 * 0:server-on-network [ServerOnNetwork] Server information received.
 *    (The RecordId datatype member is defined internally in the
 *    server. It does not have semantic meaning here.)
 * 0:remote-address [String]
 *    IP-address or other host identifier from which the information
 *    was received.
 * 0:ttl [UInt32]
 *    Time-to-live of DNS information. Zero means infinite
 *    (if the server is not currently getting removed).
 * 0:server-added [Boolean]
 *    They entry was added.
 * 0:server-updated [Boolean]
 *    An existing entry was updated.
 * 0:server-removed [Boolean]
 *    The entry was removed. */
#define UA_APPLICATIONNOTIFICATIONTYPE_DISCOVERY_SERVERONNETWORK \
    ((0x80ULL << 32) | 0x02)

Connection State

typedef enum {
    UA_CONNECTIONSTATE_CLOSED,     /* The socket has been closed and the connection
                                    * will be deleted */
    UA_CONNECTIONSTATE_OPENING,    /* The socket is open, but the connection not yet
                                      fully established */
    UA_CONNECTIONSTATE_ESTABLISHED,/* The socket is open and the connection
                                    * configured */
    UA_CONNECTIONSTATE_CLOSING,    /* The socket is closing down */
    UA_CONNECTIONSTATE_BLOCKING,   /* Listening disabled (e.g. max connections reached) */
    UA_CONNECTIONSTATE_REOPENING   /* Listening resumed after being blocked */
} UA_ConnectionState;

typedef enum {
    UA_SECURECHANNELSTATE_CLOSED = 0,
    UA_SECURECHANNELSTATE_REVERSE_LISTENING,
    UA_SECURECHANNELSTATE_CONNECTING,
    UA_SECURECHANNELSTATE_CONNECTED,
    UA_SECURECHANNELSTATE_REVERSE_CONNECTED,
    UA_SECURECHANNELSTATE_RHE_SENT,
    UA_SECURECHANNELSTATE_HEL_SENT,
    UA_SECURECHANNELSTATE_HEL_RECEIVED,
    UA_SECURECHANNELSTATE_ACK_SENT,
    UA_SECURECHANNELSTATE_ACK_RECEIVED,
    UA_SECURECHANNELSTATE_OPN_SENT,
    UA_SECURECHANNELSTATE_OPEN,
    UA_SECURECHANNELSTATE_CLOSING,
} UA_SecureChannelState;

typedef enum {
    UA_SESSIONSTATE_CLOSED = 0,
    UA_SESSIONSTATE_CREATE_REQUESTED,
    UA_SESSIONSTATE_CREATED,
    UA_SESSIONSTATE_ACTIVATE_REQUESTED,
    UA_SESSIONSTATE_ACTIVATED,
    UA_SESSIONSTATE_CLOSING
} UA_SessionState;

Statistic Counters

The stack manages statistic counters for SecureChannels and Sessions.

The Session layer counters are matching the counters of the ServerDiagnosticsSummaryDataType that are defined in the OPC UA Part 5 specification. The SecureChannel counters are not defined in the OPC UA spec, but are harmonized with the Session layer counters if possible.

typedef enum {
    UA_SHUTDOWNREASON_CLOSE = 0,
    UA_SHUTDOWNREASON_REJECT,
    UA_SHUTDOWNREASON_SECURITYREJECT,
    UA_SHUTDOWNREASON_TIMEOUT,
    UA_SHUTDOWNREASON_ABORT,
    UA_SHUTDOWNREASON_PURGE
} UA_ShutdownReason;

typedef struct {
    size_t currentChannelCount;
    size_t cumulatedChannelCount;
    size_t rejectedChannelCount;
    size_t channelTimeoutCount; /* only used by servers */
    size_t channelAbortCount;
    size_t channelPurgeCount;   /* only used by servers */
} UA_SecureChannelStatistics;

typedef struct {
    size_t currentSessionCount;
    size_t cumulatedSessionCount;
    size_t securityRejectedSessionCount; /* only used by servers */
    size_t rejectedSessionCount;
    size_t sessionTimeoutCount;          /* only used by servers */
    size_t sessionAbortCount;            /* only used by servers */
} UA_SessionStatistics;

Lifecycle States

Generic lifecycle states. The STOPPING state indicates that the lifecycle is being terminated. But it might take time to (asynchronously) perform a graceful shutdown.

typedef enum {
    UA_LIFECYCLESTATE_STOPPED = 0,
    UA_LIFECYCLESTATE_STARTED,
    UA_LIFECYCLESTATE_STOPPING
} UA_LifecycleState;