mirror of
https://github.com/open62541/open62541.git
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Julius Pfrommer
98 lines
4.3 KiB
C
98 lines
4.3 KiB
C
/* This work is licensed under a Creative Commons CCZero 1.0 Universal License.
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* See http://creativecommons.org/publicdomain/zero/1.0/ for more information. */
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#include <open62541/plugin/log_stdout.h>
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#include <open62541/server.h>
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/**
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* Generating events
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* -----------------
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* To make sense of the many things going on in a server, monitoring items can
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* be useful. Though in many cases, data change does not convey enough
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* information to be the optimal solution. Events can be generated at any time,
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* hold a lot of information and can be filtered so the client only receives the
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* specific attributes of interest.
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*
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* Emitting events by calling methods
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* ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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* The following example will be based on the server method tutorial. We will be
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* creating a method node which generates an event from the server node.
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*
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* The event we want to generate should be very simple. Since the `BaseEventType` is abstract,
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* we will have to create our own event type. `EventTypes` are saved internally as `ObjectTypes`,
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* so add the type as you would a new `ObjectType`. */
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static UA_NodeId eventType;
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static UA_StatusCode
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addNewEventType(UA_Server *server) {
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UA_ObjectTypeAttributes attr = UA_ObjectTypeAttributes_default;
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attr.displayName = UA_LOCALIZEDTEXT("en-US", "SimpleEventType");
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attr.description = UA_LOCALIZEDTEXT("en-US", "The simple event type we created");
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return UA_Server_addObjectTypeNode(server, UA_NODEID_NULL,
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UA_NS0ID(BASEEVENTTYPE), UA_NS0ID(HASSUBTYPE),
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UA_QUALIFIEDNAME(0, "SimpleEventType"),
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attr, NULL, &eventType);
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}
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/**
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* Creating an event
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* ^^^^^^^^^^^^^^^^^
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* In order to set up the event, we can first use ``UA_Server_createEvent`` to
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* give us a node representation of the event. All we need for this is our
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* `EventType`. Once we have our event node, which is saved internally as an
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* `ObjectNode`, we can define the attributes the event has the same way we
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* would define the attributes of an object node. It is not necessary to define
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* the attributes `EventId`, `ReceiveTime`, `SourceNode` or `EventType` since
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* these are set automatically by the server. In this example, we will be
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* setting the fields 'Message' and 'Severity' in addition to `Time` which is
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* needed to make the example UaExpert compliant.
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*/
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static UA_StatusCode
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createEventMethodCallback(UA_Server *server,
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const UA_NodeId *sessionId, void *sessionHandle,
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const UA_NodeId *methodId, void *methodContext,
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const UA_NodeId *objectId, void *objectContext,
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size_t inputSize, const UA_Variant *input,
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size_t outputSize, UA_Variant *output) {
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UA_LOG_INFO(UA_Log_Stdout, UA_LOGCATEGORY_APPLICATION, "Creating event");
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UA_UInt16 severity = 100;
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UA_LocalizedText message = UA_LOCALIZEDTEXT("en-US", "An event has been generated.");
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UA_StatusCode res = UA_Server_createEvent(server, UA_NS0ID(SERVER), eventType,
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severity, message, NULL, NULL, NULL);
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if(res != UA_STATUSCODE_GOOD) {
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UA_LOG_WARNING(UA_Log_Stdout, UA_LOGCATEGORY_APPLICATION,
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"Creating event failed. StatusCode %s",
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UA_StatusCode_name(res));
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}
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return res;
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}
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/**
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* Now, all that is left to do is to create a method node which triggers the
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* event creation for the example.
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*/
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int main(void) {
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UA_Server *server = UA_Server_new();
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addNewEventType(server);
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UA_MethodAttributes generateAttr = UA_MethodAttributes_default;
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generateAttr.description = UA_LOCALIZEDTEXT("en-US","Generate an event.");
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generateAttr.displayName = UA_LOCALIZEDTEXT("en-US","Generate Event");
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generateAttr.executable = true;
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generateAttr.userExecutable = true;
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UA_Server_addMethodNode(server, UA_NODEID_NUMERIC(1, 62541),
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UA_NS0ID(OBJECTSFOLDER), UA_NS0ID(HASCOMPONENT),
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UA_QUALIFIEDNAME(1, "Generate Event"),
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generateAttr, &createEventMethodCallback,
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0, NULL, 0, NULL, NULL, NULL);
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UA_Server_runUntilInterrupt(server);
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UA_Server_delete(server);
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return 0;
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}
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