Include code from server_firstSteps.c in documentation (#694)

* Include code from server_firstSteps.c in documentation

* add other tutorials

align other examples with tutorial

doc/tutorial_client_firstSteps.rst

@@ -34,47 +34,11 @@ Reading a node attibute
 In this example we are going to connect to the server from the second tutorial
 and read the value-attribute of the added variable node.
 
-.. code-block:: c
-
-    #include <stdio.h>
-    #include "open62541.h"
-
-    int main(int argc, char *argv[])
-    {
-        /* create a client and connect */
-        UA_Client *client = UA_Client_new(UA_ClientConfig_standard);
-        UA_StatusCode retval = UA_Client_connect(client, "opc.tcp://localhost:16664");
-        if(retval != UA_STATUSCODE_GOOD) {
-            UA_Client_delete(client);
-            return retval;
-        }
+.. literalinclude:: ../../examples/client_firstSteps.c
+   :language: c
+   :linenos:
+   :lines: 4,5,12,14-
 
-        /* create a readrequest with one entry */
-        UA_ReadRequest req;
-        UA_ReadRequest_init(&req);
-        req.nodesToRead = UA_Array_new(1, &UA_TYPES[UA_TYPES_READVALUEID]);
-        req.nodesToReadSize = 1;
-
-        /* define the node and attribute to be read */
-        req.nodesToRead[0].nodeId = UA_NODEID_STRING_ALLOC(1, "the.answer");
-        req.nodesToRead[0].attributeId = UA_ATTRIBUTEID_VALUE;
-
-        /* call the service and print the result */
-        UA_ReadResponse resp = UA_Client_Service_read(client, req);
-        if(resp.responseHeader.serviceResult == UA_STATUSCODE_GOOD &&
-           resp.resultsSize > 0 && resp.results[0].hasValue &&
-           UA_Variant_isScalar(&resp.results[0].value) &&
-            resp.results[0].value.type == &UA_TYPES[UA_TYPES_INT32]) {
-            UA_Int32 *value = (UA_Int32*)resp.results[0].value.data;
-            printf("the value is: %i\n", *value);
-        }
-
-        UA_ReadRequest_deleteMembers(&req);
-        UA_ReadResponse_deleteMembers(&resp);
-        UA_Client_disconnect(client);
-        UA_Client_delete(client);
-        return UA_STATUSCODE_GOOD;
-    }
 
 Further tasks
 -------------

doc/tutorial_server_firstSteps.rst

@@ -17,31 +17,10 @@ have the ``open62541.c/.h`` files in the current folder.
 
 Now create a new C source-file called ``myServer.c`` with the following content:
 
-.. code-block:: c
-
-   #include <signal.h>
-   #include "open62541.h"
-
-   UA_Boolean running = true;
-   void signalHandler(int sig) {
-       running = false;
-   }
-
-   int main(void) {
-       signal(SIGINT, signalHandler); /* catch ctrl-c */
-
-       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);
-       UA_Server_run(server, &running);
-       UA_Server_delete(server);
-       nl.deleteMembers(&nl);
-
-       return 0;
-   }
+.. literalinclude:: ../../examples/server_firstSteps.c
+   :language: c
+   :linenos:
+   :lines: 4,12,14-34
 
 This is all that is needed for a simple OPC UA server. Compile the the server
 with GCC using the following command:

doc/tutorial_server_method.rst

@@ -5,82 +5,18 @@ 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
+The first example shows how to define input and output arguments (lines 72 - 88),
+make the method executable (lines 94,95), add the method node (line 96-101)
+with a specified method callback (lines 10 - 24).
 
-    #include <signal.h>
-    #include <stdlib.h>
-    #include "open62541.h"
+The second example shows that a method can also be applied on an array
+as input argument and output argument.
 
-    UA_Boolean running = true;
-    static void stopHandler(int sign) {
-        UA_LOG_INFO(logger, UA_LOGCATEGORY_SERVER, "received ctrl-c");
-        running = 0;
-    }
+The last example presents a way to bind a new method callback to an already
+instantiated method node.
 
-    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;
-    }
+.. literalinclude:: ../../examples/server_method.c
+   :language: c
+   :linenos:
+   :lines: 4,5,14,16-

doc/tutorial_server_variables.rst

@@ -11,57 +11,18 @@ connected to a physical process in the background. Make sure to read the
 This is the code for a server with a single variable node holding an integer. We
 will take this example to explain some of the fundamental concepts of open62541.
 
-.. code-block:: c
+.. literalinclude:: ../../examples/server_variable.c
+   :language: c
+   :linenos:
+   :lines: 4,13,15-
 
-    #include <signal.h>
-    #include "open62541.h"
-
-    UA_Boolean running = true;
-    static void stopHandler(int sign) {
-        running = false;
-    }
-
-    int main(int argc, char** argv) {
-        signal(SIGINT, stopHandler); /* catch ctrl-c */
-
-        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);
-
-        /* 1) Define the attribute of the myInteger variable node */
-        UA_VariableAttributes attr;
-        UA_VariableAttributes_init(&attr);
-        UA_Int32 myInteger = 42;
-        UA_Variant_setScalar(&attr.value, &myInteger, &UA_TYPES[UA_TYPES_INT32]);
-        attr.description = UA_LOCALIZEDTEXT("en_US","the answer");
-        attr.displayName = UA_LOCALIZEDTEXT("en_US","the answer");
-
-        /* 2) Add the variable node to the information model */
-        UA_NodeId myIntegerNodeId = UA_NODEID_STRING(1, "the.answer");
-        UA_QualifiedName myIntegerName = UA_QUALIFIEDNAME(1, "the answer");
-        UA_NodeId parentNodeId = UA_NODEID_NUMERIC(0, UA_NS0ID_OBJECTSFOLDER);
-        UA_NodeId parentReferenceNodeId = UA_NODEID_NUMERIC(0, UA_NS0ID_ORGANIZES);
-        UA_StatusCode retval = UA_Server_addVariableNode(server, myIntegerNodeId, parentNodeId,
-                                                         parentReferenceNodeId, myIntegerName,
-                                                         UA_NODEID_NULL, attr, NULL, NULL);
-
-        if(retval == UA_STATUSCODE_GOOD)
-            UA_Server_run(server, &running);
-
-        UA_Server_delete(server);
-        nl.deleteMembers(&nl);
-
-        return retval;
-    }
 
 Variants and Datatypes
 ----------------------
 
 The datatype *variant* belongs to the built-in datatypes of OPC UA and is used
 as a container type. A variant can hold any other datatype as a scalar (except
-Variant) or as an array. Array variants can additionally denote the
+variant) or as an array. Array variants can additionally denote the
 dimensionality of the data (e.g. a 2x3 matrix) in an additional integer array.
 You can find the code that defines the variant datatype :ref:`here <variant>`.
 
@@ -133,6 +94,10 @@ some examples for their usage.
    UA_NodeId id3 = UA_NODEID_STRING_ALLOC(1, "testid");
    UA_NodeId_deleteMembers(&id3); /* free the allocated string */
 
+
+What is UA_NODEID_STRING_ALLOC for?
+
+
 Adding a variable node to the server that contains a user-defined callback
 --------------------------------------------------------------------------
 
@@ -143,6 +108,12 @@ callback pointer is intserted into the node.
 Consider ``examples/server_datasource.c`` in the repository. The examples are
 compiled if the Cmake option UA_BUILD_EXAMPLE is turned on.
 
+
+UA_Server_addVariableNode vs. UA_Server_addDataSourceVariableNode
+UA_ValueCallback
+UA_DataSource
+
+
 Asserting success/failure
 -------------------------
 

examples/client_firstSteps.c

@@ -5,11 +5,11 @@
 #include <inttypes.h>
 
 #ifdef UA_NO_AMALGAMATION
-# include "ua_client.h"
-# include "ua_config_standard.h"
-# include "ua_network_tcp.h"
+#include "ua_client.h"
+#include "ua_config_standard.h"
+#include "ua_network_tcp.h"
 #else
-# include "open62541.h"
+#include "open62541.h"
 #endif
 
 int main(void) {
@@ -24,13 +24,18 @@ int main(void) {
     UA_DateTime raw_date = 0;
     UA_String string_date;
 
+    /* create a readrequest with one entry */
     UA_ReadRequest rReq;
     UA_ReadRequest_init(&rReq);
     rReq.nodesToRead = UA_Array_new(1, &UA_TYPES[UA_TYPES_READVALUEID]);
     rReq.nodesToReadSize = 1;
-    rReq.nodesToRead[0].nodeId = UA_NODEID_NUMERIC(0, 2258);
+
+    /* define the node and attribute to be read */
+    #define NS0_CURRENT_TIME 2258
+    rReq.nodesToRead[0].nodeId = UA_NODEID_NUMERIC(0, NS0_CURRENT_TIME);
     rReq.nodesToRead[0].attributeId = UA_ATTRIBUTEID_VALUE;
 
+    /* call the service and print the result */
     UA_ReadResponse rResp = UA_Client_Service_read(client, rReq);
     if(rResp.responseHeader.serviceResult == UA_STATUSCODE_GOOD && rResp.resultsSize > 0 &&
        rResp.results[0].hasValue && UA_Variant_isScalar(&rResp.results[0].value) &&

examples/server_firstSteps.c

@@ -1,16 +1,15 @@
 /* This work is licensed under a Creative Commons CCZero 1.0 Universal License.
  * See http://creativecommons.org/publicdomain/zero/1.0/ for more information. */
 
-#include <stdio.h>
 #include <signal.h>
 
 #ifdef UA_NO_AMALGAMATION
-# include "ua_types.h"
-# include "ua_server.h"
-# include "ua_config_standard.h"
-# include "ua_network_tcp.h"
+#include "ua_types.h"
+#include "ua_server.h"
+#include "ua_config_standard.h"
+#include "ua_network_tcp.h"
 #else
-# include "open62541.h"
+#include "open62541.h"
 #endif
 
 UA_Boolean running = true;

examples/server_method.c

@@ -5,18 +5,20 @@
 #include <stdlib.h>
 
 #ifdef UA_NO_AMALGAMATION
-# include "ua_types.h"
-# include "ua_server.h"
-# include "ua_config_standard.h"
-# include "ua_network_tcp.h"
-# include "ua_log_stdout.h"
+#include "ua_types.h"
+#include "ua_server.h"
+#include "ua_config_standard.h"
+#include "ua_network_tcp.h"
+#include "ua_log_stdout.h"
 #else
-# include "open62541.h"
+#include "open62541.h"
 #endif
 
 UA_Boolean running = true;
 UA_Logger logger = UA_Log_Stdout;
 
+
+// EXAMPLE 1 method
 static UA_StatusCode
 helloWorldMethod(void *handle, const UA_NodeId objectId, size_t inputSize, const UA_Variant *input,
                  size_t outputSize, UA_Variant *output) {
@@ -33,6 +35,18 @@ helloWorldMethod(void *handle, const UA_NodeId objectId, size_t inputSize, const
         return UA_STATUSCODE_GOOD;
 }
 
+// EXAMPLE 2 method
+static UA_StatusCode
+IncInt32ArrayValuesMethod(void *handle, const UA_NodeId objectId, size_t inputSize,
+                          const UA_Variant *input, size_t outputSize, UA_Variant *output) {
+    UA_Variant_setArrayCopy(output, input->data, 5, &UA_TYPES[UA_TYPES_INT32]);
+    for(size_t i = 0; i< input->arrayLength; i++)
+        ((UA_Int32*)output->data)[i] = ((UA_Int32*)input->data)[i] + 1;
+    return UA_STATUSCODE_GOOD;
+}
+
+
+// EXAMPLE 3 method
 static UA_StatusCode
 fooBarMethod(void *handle, const UA_NodeId objectId, size_t inputSize, const UA_Variant *input,
                  size_t outputSize, UA_Variant *output) {
@@ -46,19 +60,10 @@ fooBarMethod(void *handle, const UA_NodeId objectId, size_t inputSize, const UA_
         }
         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");
+        UA_LOG_INFO(logger, UA_LOGCATEGORY_SERVER, "FooBar was called");
         return UA_STATUSCODE_GOOD;
 }
 
-static UA_StatusCode
-IncInt32ArrayValuesMethod(void *handle, const UA_NodeId objectId, size_t inputSize,
-                          const UA_Variant *input, size_t outputSize, UA_Variant *output) {
-    UA_Variant_setArrayCopy(output, input->data, 5, &UA_TYPES[UA_TYPES_INT32]);
-    for(size_t i = 0; i< input->arrayLength; i++)
-        ((UA_Int32*)output->data)[i] = ((UA_Int32*)input->data)[i] + 1;
-    return UA_STATUSCODE_GOOD;
-}
-
 static void stopHandler(int sign) {
     UA_LOG_INFO(logger, UA_LOGCATEGORY_SERVER, "received ctrl-c");
     running = 0;
@@ -76,23 +81,23 @@ int main(int argc, char** argv) {
 
     //EXAMPLE 1
     /* 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_Argument inputArguments1;
+    UA_Argument_init(&inputArguments1);
+    inputArguments1.arrayDimensionsSize = 0;
+    inputArguments1.arrayDimensions = NULL;
+    inputArguments1.dataType = UA_TYPES[UA_TYPES_STRING].typeId;
+    inputArguments1.description = UA_LOCALIZEDTEXT("en_US", "A String");
+    inputArguments1.name = UA_STRING("MyInput");
+    inputArguments1.valueRank = -1;
+
+    UA_Argument outputArguments1;
+    UA_Argument_init(&outputArguments1);
+    outputArguments1.arrayDimensionsSize = 0;
+    outputArguments1.arrayDimensions = NULL;
+    outputArguments1.dataType = UA_TYPES[UA_TYPES_STRING].typeId;
+    outputArguments1.description = UA_LOCALIZEDTEXT("en_US", "A String");
+    outputArguments1.name = UA_STRING("MyOutput");
+    outputArguments1.valueRank = -1;
 
     UA_MethodAttributes helloAttr;
     UA_MethodAttributes_init(&helloAttr);
@@ -103,36 +108,37 @@ int main(int argc, char** argv) {
     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"), 
+                            UA_QUALIFIEDNAME(1, "hello world"),
                             helloAttr, &helloWorldMethod, NULL,
-                            1, &inputArguments, 1, &outputArguments, NULL);
-
+                            1, &inputArguments1, 1, &outputArguments1, NULL);
     //END OF EXAMPLE 1
 
     //EXAMPLE 2
     /* add another method node: output argument as 1d Int32 array*/
     // define input arguments
-    UA_Argument_init(&inputArguments);
-    inputArguments.arrayDimensionsSize = 1;
+    UA_Argument inputArguments2;
+    UA_Argument_init(&inputArguments2);
+    inputArguments2.arrayDimensionsSize = 1;
     UA_UInt32 * pInputDimensions = UA_UInt32_new();
     pInputDimensions[0] = 5;
-    inputArguments.arrayDimensions = pInputDimensions;
-    inputArguments.dataType = UA_TYPES[UA_TYPES_INT32].typeId;
-    inputArguments.description = UA_LOCALIZEDTEXT("en_US",
+    inputArguments2.arrayDimensions = pInputDimensions;
+    inputArguments2.dataType = UA_TYPES[UA_TYPES_INT32].typeId;
+    inputArguments2.description = UA_LOCALIZEDTEXT("en_US",
                     "input an array with 5 elements, type int32");
-    inputArguments.name = UA_STRING("int32 value");
-    inputArguments.valueRank = 1;
+    inputArguments2.name = UA_STRING("int32 value");
+    inputArguments2.valueRank = 1;
 
     // define output arguments
-    UA_Argument_init(&outputArguments);
-    outputArguments.arrayDimensionsSize = 1;
+    UA_Argument outputArguments2;
+    UA_Argument_init(&outputArguments2);
+    outputArguments2.arrayDimensionsSize = 1;
     UA_UInt32 * pOutputDimensions = UA_UInt32_new();
     pOutputDimensions[0] = 5;
-    outputArguments.arrayDimensions = pOutputDimensions;
-    outputArguments.dataType = UA_TYPES[UA_TYPES_INT32].typeId;
-    outputArguments.description = UA_LOCALIZEDTEXT("en_US", "increment each array index");
-    outputArguments.name = UA_STRING("output is the array, each index is incremented by one");
-    outputArguments.valueRank = 1;
+    outputArguments2.arrayDimensions = pOutputDimensions;
+    outputArguments2.dataType = UA_TYPES[UA_TYPES_INT32].typeId;
+    outputArguments2.description = UA_LOCALIZEDTEXT("en_US", "increment each array index");
+    outputArguments2.name = UA_STRING("output is the array, each index is incremented by one");
+    outputArguments2.valueRank = 1;
 
     UA_MethodAttributes incAttr;
     UA_MethodAttributes_init(&incAttr);
@@ -142,18 +148,30 @@ int main(int argc, char** argv) {
     incAttr.userExecutable = true;
     UA_Server_addMethodNode(server, UA_NODEID_STRING(1, "IncInt32ArrayValues"),
                             UA_NODEID_NUMERIC(0, UA_NS0ID_OBJECTSFOLDER),
-                            UA_NODEID_NUMERIC(0, UA_NS0ID_HASCOMPONENT), 
+                            UA_NODEID_NUMERIC(0, UA_NS0ID_HASCOMPONENT),
                             UA_QUALIFIEDNAME(1, "IncInt32ArrayValues"),
                             incAttr, &IncInt32ArrayValuesMethod, NULL,
-                            1, &inputArguments, 1, &outputArguments, NULL);
+                            1, &inputArguments2, 1, &outputArguments2, NULL);
     //END OF EXAMPLE 2
 
-    /* If out methodnode is part of an instantiated object, we never had
-       the opportunity to define the callback... we could do that now
-    */
-    UA_Server_setMethodNode_callback(server, UA_NODEID_NUMERIC(1,62541), &fooBarMethod, NULL);
-
+    //EXAMPLE 3
+    UA_MethodAttributes method3Attr;
+    UA_MethodAttributes_init(&method3Attr);
+    method3Attr.description = UA_LOCALIZEDTEXT("en_US","FooBar");
+    method3Attr.displayName = UA_LOCALIZEDTEXT("en_US","FooBar");
+    method3Attr.executable = true;
+    method3Attr.userExecutable = true;
+    UA_Server_addMethodNode(server, UA_NODEID_STRING(1,"FooBar"),
+                            UA_NODEID_NUMERIC(0, UA_NS0ID_OBJECTSFOLDER),
+                            UA_NODEID_NUMERIC(0, UA_NS0ID_HASCOMPONENT),
+                            UA_QUALIFIEDNAME(1, "FooBar"),
+                            method3Attr, NULL, NULL,
+                            1, &inputArguments1, 1, &outputArguments1, NULL);
+    /*  If the method node has no callback (because it was instantiated without one) or
+        if we just want to change it, this can be done with UA_Server_setMethodNode_callback() */
+    UA_Server_setMethodNode_callback(server,  UA_NODEID_NUMERIC(1,62542), &fooBarMethod, NULL);
     //END OF EXAMPLE 3
+
     /* start server */
     UA_StatusCode retval = UA_Server_run(server, &running);
 

examples/server_variable.c

@@ -4,13 +4,13 @@
 #include <signal.h>
 
 #ifdef UA_NO_AMALGAMATION
-# include "ua_types.h"
-# include "ua_server.h"
-# include "ua_config_standard.h"
-# include "ua_network_tcp.h"
-# include "ua_log_stdout.h"
+#include "ua_types.h"
+#include "ua_server.h"
+#include "ua_config_standard.h"
+#include "ua_network_tcp.h"
+#include "ua_log_stdout.h"
 #else
-# include "open62541.h"
+#include "open62541.h"
 #endif
 
 UA_Boolean running = true;
@@ -38,13 +38,15 @@ int main(int argc, char** argv) {
     config.networkLayersSize = 1;
     UA_Server *server = UA_Server_new(config);
 
-    /* add a variable node to the address space */
+    /* 1) Define the attribute of the myInteger variable node */
     UA_VariableAttributes attr;
     UA_VariableAttributes_init(&attr);
-    /* UA_Int32 myInteger = 42; */
-    /* UA_Variant_setScalar(&attr.value, &myInteger, &UA_TYPES[UA_TYPES_INT32]); */
-    /* attr.description = UA_LOCALIZEDTEXT("en_US","the answer"); */
-    /* attr.displayName = UA_LOCALIZEDTEXT("en_US","the answer"); */
+    UA_Int32 myInteger = 42;
+    UA_Variant_setScalar(&attr.value, &myInteger, &UA_TYPES[UA_TYPES_INT32]);
+    attr.description = UA_LOCALIZEDTEXT("en_US","the answer");
+    attr.displayName = UA_LOCALIZEDTEXT("en_US","the answer");
+
+    /* 2) Add the variable node to the information model */
     UA_NodeId myIntegerNodeId = UA_NODEID_STRING(1, "the.answer");
     UA_QualifiedName myIntegerName = UA_QUALIFIEDNAME(1, "the answer");
     UA_NodeId parentNodeId = UA_NODEID_NUMERIC(0, UA_NS0ID_OBJECTSFOLDER);