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/* This work is licensed under a Creative Commons CCZero 1.0 Universal License.
* See http://creativecommons.org/publicdomain/zero/1.0/ for more information. */
/**
* Working with Variable Types
* ---------------------------
*
* Variable types have three functions:
*
* - Constrain the possible data type, value rank and array dimensions of the
* variables of that type. This allows interface code to be written against
* the generic type definition, so it is applicable for all instances.
* - Provide a sensible default value
* - Enable a semantic interpretation of the variable based on its type
*
* In the example of this tutorial, we represent a point in 2D space by an array
* of double values. The following function adds the corresponding
* VariableTypeNode to the hierarchy of variable types.
*/
#include <open62541/plugin/log_stdout.h>
#include <open62541/server.h>
static UA_NodeId pointTypeId;
static void
addVariableType2DPoint(UA_Server *server) {
UA_VariableTypeAttributes vtAttr = UA_VariableTypeAttributes_default;
vtAttr.dataType = UA_TYPES[UA_TYPES_DOUBLE].typeId;
vtAttr.valueRank = UA_VALUERANK_ONE_DIMENSION;
UA_UInt32 arrayDims[1] = {2};
vtAttr.arrayDimensions = arrayDims;
vtAttr.arrayDimensionsSize = 1;
vtAttr.displayName = UA_LOCALIZEDTEXT("en-US", "2DPoint Type");
/* a matching default value is required */
UA_Double zero[2] = {0.0, 0.0};
UA_Variant_setArray(&vtAttr.value, zero, 2, &UA_TYPES[UA_TYPES_DOUBLE]);
UA_Server_addVariableTypeNode(server, UA_NODEID_NULL,
UA_NODEID_NUMERIC(0, UA_NS0ID_BASEDATAVARIABLETYPE),
UA_NODEID_NUMERIC(0, UA_NS0ID_HASSUBTYPE),
UA_QUALIFIEDNAME(1, "2DPoint Type"), UA_NODEID_NULL,
vtAttr, NULL, &pointTypeId);
}
/**
* Now the new variable type for *2DPoint* can be referenced during the creation
* of a new variable. If no value is given, the default from the variable type
* is copied during instantiation.
*/
static UA_NodeId pointVariableId;
static void
addVariable(UA_Server *server) {
/* Prepare the node attributes */
UA_VariableAttributes vAttr = UA_VariableAttributes_default;
vAttr.dataType = UA_TYPES[UA_TYPES_DOUBLE].typeId;
vAttr.valueRank = UA_VALUERANK_ONE_DIMENSION;
UA_UInt32 arrayDims[1] = {2};
vAttr.arrayDimensions = arrayDims;
vAttr.arrayDimensionsSize = 1;
vAttr.displayName = UA_LOCALIZEDTEXT("en-US", "2DPoint Variable");
vAttr.accessLevel = UA_ACCESSLEVELMASK_READ | UA_ACCESSLEVELMASK_WRITE;
/* vAttr.value is left empty, the server instantiates with the default value */
/* Add the node */
UA_Server_addVariableNode(server, UA_NODEID_NULL,
UA_NODEID_NUMERIC(0, UA_NS0ID_OBJECTSFOLDER),
UA_NODEID_NUMERIC(0, UA_NS0ID_HASCOMPONENT),
UA_QUALIFIEDNAME(1, "2DPoint Type"), pointTypeId,
vAttr, NULL, &pointVariableId);
}
/**
* The constraints of the variable type are enforced when creating new variable
* instances of the type. In the following function, adding a variable of
* *2DPoint* type with a string value fails because the value does not match the
* variable type constraints. */
static void
addVariableFail(UA_Server *server) {
/* Prepare the node attributes */
UA_VariableAttributes vAttr = UA_VariableAttributes_default;
vAttr.dataType = UA_TYPES[UA_TYPES_DOUBLE].typeId;
vAttr.valueRank = UA_VALUERANK_SCALAR; /* a scalar. this is not allowed per
* the variable type */
vAttr.displayName = UA_LOCALIZEDTEXT("en-US", "2DPoint Variable (fail)");
UA_String s = UA_STRING("2dpoint?");
UA_Variant_setScalar(&vAttr.value, &s, &UA_TYPES[UA_TYPES_STRING]);
/* Add the node will return UA_STATUSCODE_BADTYPEMISMATCH*/
UA_Server_addVariableNode(server, UA_NODEID_NULL,
UA_NODEID_NUMERIC(0, UA_NS0ID_OBJECTSFOLDER),
UA_NODEID_NUMERIC(0, UA_NS0ID_HASCOMPONENT),
UA_QUALIFIEDNAME(1, "2DPoint Type (fail)"), pointTypeId,
vAttr, NULL, NULL);
}
/**
* The constraints of the variable type are enforced when writing the datatype,
* valuerank and arraydimensions attributes of the variable. This, in turn,
* constrains the value attribute of the variable. */
static void
writeVariable(UA_Server *server) {
UA_StatusCode retval =
UA_Server_writeValueRank(server, pointVariableId,
UA_VALUERANK_ONE_OR_MORE_DIMENSIONS);
UA_LOG_INFO(UA_Log_Stdout, UA_LOGCATEGORY_USERLAND,
"Setting the Value Rank failed with Status Code %s",
UA_StatusCode_name(retval));
}
/** It follows the main server code, making use of the above definitions. */
int main(void) {
UA_Server *server = UA_Server_new();
addVariableType2DPoint(server);
addVariable(server);
addVariableFail(server);
writeVariable(server);
UA_Server_runUntilInterrupt(server);
UA_Server_delete(server);
return 0;
}
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