open62541/doc/tutorial_server_method.rst

3. Adding a server-side method
==============================

This tutorial demonstrates how to add method nodes to the server. Use an UA
client, e.g., UaExpert to call the method (right-click on the method node ->
call).

.. code-block:: c

    #include <signal.h>
    #include <stdlib.h>
    #include "open62541.h"

    UA_Boolean running = true;
    static void stopHandler(int sign) {
        UA_LOG_INFO(logger, UA_LOGCATEGORY_SERVER, "received ctrl-c");
        running = 0;
    }

    UA_Logger logger = UA_Log_Stdout;

    static UA_StatusCode
    helloWorldMethod(void *handle, const UA_NodeId objectId, size_t inputSize,
                     const UA_Variant *input, size_t outputSize, UA_Variant *output) {
            UA_String *inputStr = (UA_String*)input->data;
            UA_String tmp = UA_STRING_ALLOC("Hello ");
            if(inputStr->length > 0) {
                tmp.data = realloc(tmp.data, tmp.length + inputStr->length);
                memcpy(&tmp.data[tmp.length], inputStr->data, inputStr->length);
                tmp.length += inputStr->length;
            }
            UA_Variant_setScalarCopy(output, &tmp, &UA_TYPES[UA_TYPES_STRING]);
            UA_String_deleteMembers(&tmp);
            UA_LOG_INFO(logger, UA_LOGCATEGORY_SERVER, "Hello World was called");
            return UA_STATUSCODE_GOOD;
    }

    int main(int argc, char** argv) {
        signal(SIGINT, stopHandler); /* catches ctrl-c */

        /* initialize the server */
        UA_ServerConfig config = UA_ServerConfig_standard;
        UA_ServerNetworkLayer nl = UA_ServerNetworkLayerTCP(UA_ConnectionConfig_standard, 16664);
        config.networkLayers = &nl;
        config.networkLayersSize = 1;
        UA_Server *server = UA_Server_new(config);

        /* add the method node with the callback */
        UA_Argument inputArguments;
        UA_Argument_init(&inputArguments);
        inputArguments.arrayDimensionsSize = 0;
        inputArguments.arrayDimensions = NULL;
        inputArguments.dataType = UA_TYPES[UA_TYPES_STRING].typeId;
        inputArguments.description = UA_LOCALIZEDTEXT("en_US", "A String");
        inputArguments.name = UA_STRING("MyInput");
        inputArguments.valueRank = -1;

        UA_Argument outputArguments;
        UA_Argument_init(&outputArguments);
        outputArguments.arrayDimensionsSize = 0;
        outputArguments.arrayDimensions = NULL;
        outputArguments.dataType = UA_TYPES[UA_TYPES_STRING].typeId;
        outputArguments.description = UA_LOCALIZEDTEXT("en_US", "A String");
        outputArguments.name = UA_STRING("MyOutput");
        outputArguments.valueRank = -1;

        UA_MethodAttributes helloAttr;
        UA_MethodAttributes_init(&helloAttr);
        helloAttr.description = UA_LOCALIZEDTEXT("en_US","Say `Hello World`");
        helloAttr.displayName = UA_LOCALIZEDTEXT("en_US","Hello World");
        helloAttr.executable = true;
        helloAttr.userExecutable = true;
        UA_Server_addMethodNode(server, UA_NODEID_NUMERIC(1,62541),
                                UA_NODEID_NUMERIC(0, UA_NS0ID_OBJECTSFOLDER),
                                UA_NODEID_NUMERIC(0, UA_NS0ID_HASORDEREDCOMPONENT),
                                UA_QUALIFIEDNAME(1, "hello world"), 
                                helloAttr, &helloWorldMethod, NULL,
                                1, &inputArguments, 1, &outputArguments, NULL);

        /* run the server */
        UA_Server_run(server, &running);
        UA_Server_delete(server);
        nl.deleteMembers(&nl);

        return 0;
    }