open62541/examples/pubsub/tutorial_pubsub_publish.c

/* This work is licensed under a Creative Commons CCZero 1.0 Universal License.
 * See http://creativecommons.org/publicdomain/zero/1.0/ for more information. */

/**
 * .. _pubsub-tutorial:
 *
 * Working with Publish/Subscribe
 * ------------------------------
 *
 * Work in progress:
 * This Tutorial will be continuously extended during the next PubSub batches. More details about
 * the PubSub extension and corresponding open62541 API are located here: :ref:`pubsub`.
 *
 * Publishing Fields
 * ^^^^^^^^^^^^^^^^^
 * The PubSub publish example demonstrate the simplest way to publish
 * informations from the information model over UDP multicast using
 * the UADP encoding.
 *
 * **Connection handling**
 * PubSubConnections can be created and deleted on runtime. More details about the system preconfiguration and
 * connection can be found in ``tutorial_pubsub_connection.c``.
 */
#include <signal.h>
#include "open62541.h"
UA_NodeId connectionIdent, publishedDataSetIdent, writerGroupIdent;

static void
addPubSubConnection(UA_Server *server){
    /* Details about the connection configuration and handling are located
     * in the pubsub connection tutorial */
    UA_PubSubConnectionConfig connectionConfig;
    memset(&connectionConfig, 0, sizeof(connectionConfig));
    connectionConfig.name = UA_STRING("UDP-UADP Connection 1");
    connectionConfig.transportProfileUri = UA_STRING("http://opcfoundation.org/UA-Profile/Transport/pubsub-udp-uadp");
    connectionConfig.enabled = UA_TRUE;
    UA_NetworkAddressUrlDataType networkAddressUrl = {UA_STRING_NULL , UA_STRING("opc.udp://224.0.0.22:4840/")};
    UA_Variant_setScalar(&connectionConfig.address, &networkAddressUrl, &UA_TYPES[UA_TYPES_NETWORKADDRESSURLDATATYPE]);
    connectionConfig.publisherId.numeric = UA_UInt32_random();
    UA_Server_addPubSubConnection(server, &connectionConfig, &connectionIdent);
}

/**
 * **PublishedDataSet handling**
 * The PublishedDataSet (PDS) and PubSubConnection are the toplevel entities and can exist alone. The PDS contains
 * the collection of the published fields.
 * All other PubSub elements are directly or indirectly linked with the PDS or connection.
 */
static void
addPublishedDataSet(UA_Server *server) {
    /* The PublishedDataSetConfig contains all necessary public
    * informations for the creation of a new PublishedDataSet */
    UA_PublishedDataSetConfig publishedDataSetConfig;
    memset(&publishedDataSetConfig, 0, sizeof(UA_PublishedDataSetConfig));
    publishedDataSetConfig.publishedDataSetType = UA_PUBSUB_DATASET_PUBLISHEDITEMS;
    publishedDataSetConfig.name = UA_STRING("Demo PDS");
    /* Create new PublishedDataSet based on the PublishedDataSetConfig. */
    UA_Server_addPublishedDataSet(server, &publishedDataSetConfig, &publishedDataSetIdent);
}

/**
 * **DataSetField handling**
 * The DataSetField (DSF) is part of the PDS and describes exactly one published field.
 */
static void
addDataSetField(UA_Server *server) {
    /* Add a field to the previous created PublishedDataSet */
    UA_NodeId dataSetFieldIdent;
    UA_DataSetFieldConfig dataSetFieldConfig;
    memset(&dataSetFieldConfig, 0, sizeof(UA_DataSetFieldConfig));
    dataSetFieldConfig.dataSetFieldType = UA_PUBSUB_DATASETFIELD_VARIABLE;
    dataSetFieldConfig.field.variable.fieldNameAlias = UA_STRING("Server localtime");
    dataSetFieldConfig.field.variable.promotedField = UA_FALSE;
    dataSetFieldConfig.field.variable.publishParameters.publishedVariable =
    UA_NODEID_NUMERIC(0, UA_NS0ID_SERVER_SERVERSTATUS_CURRENTTIME);
    dataSetFieldConfig.field.variable.publishParameters.attributeId = UA_ATTRIBUTEID_VALUE;
    UA_Server_addDataSetField(server, publishedDataSetIdent, &dataSetFieldConfig, &dataSetFieldIdent);
}

/**
 * **WriterGroup handling**
 * The WriterGroup (WG) is part of the connection and contains the primary configuration
 * parameters for the message creation.
 */
static void
addWriterGroup(UA_Server *server) {
    /* Now we create a new WriterGroupConfig and add the group to the existing PubSubConnection. */
    UA_WriterGroupConfig writerGroupConfig;
    memset(&writerGroupConfig, 0, sizeof(UA_WriterGroupConfig));
    writerGroupConfig.name = UA_STRING("Demo WriterGroup");
    writerGroupConfig.publishingInterval = 100;
    writerGroupConfig.enabled = UA_FALSE;
    writerGroupConfig.writerGroupId = 100;
    writerGroupConfig.encodingMimeType = UA_PUBSUB_ENCODING_UADP;
    /* The configuration flags for the messages are encapsulated inside the
     * message- and transport settings extension objects. These extension objects
     * are defined by the standard. e.g. UadpWriterGroupMessageDataType */
    UA_Server_addWriterGroup(server, connectionIdent, &writerGroupConfig, &writerGroupIdent);
}

/**
 * **DataSetWriter handling**
 * A DataSetWriter (DSW) is the glue between the WG and the PDS. The DSW is linked to exactly one
 * PDS and contains additional informations for the message generation.
 */
static void
addDataSetWriter(UA_Server *server) {
    /* We need now a DataSetWriter within the WriterGroup. This means we must
     * create a new DataSetWriterConfig and add call the addWriterGroup function. */
    UA_NodeId dataSetWriterIdent;
    UA_DataSetWriterConfig dataSetWriterConfig;
    memset(&dataSetWriterConfig, 0, sizeof(UA_DataSetWriterConfig));
    dataSetWriterConfig.name = UA_STRING("Demo DataSetWriter");
    dataSetWriterConfig.dataSetWriterId = 62541;
    dataSetWriterConfig.keyFrameCount = 10;
    UA_Server_addDataSetWriter(server, writerGroupIdent, publishedDataSetIdent,
                               &dataSetWriterConfig, &dataSetWriterIdent);
}

/**
 * That's it! You're now publishing the selected fields.
 * Open a packet inspection tool of trust e.g. wireshark and take a look on the outgoing packages.
 * The following graphic figures out the packages created by this tutorial.
 *
 * .. figure:: ua-wireshark-pubsub.png
 *     :figwidth: 100 %
 *     :alt: OPC UA PubSub communication in wireshark
 *
 * The open62541 subscriber API will be released later. If you want to process the the datagrams,
 * take a look on the ua_network_pubsub_networkmessage.c which already contains the decoding code for UADP messages.
 *
 * It follows the main server code, making use of the above definitions. */
UA_Boolean running = true;
static void stopHandler(int sign) {
    UA_LOG_INFO(UA_Log_Stdout, UA_LOGCATEGORY_SERVER, "received ctrl-c");
    running = false;
}

int main(void) {
    signal(SIGINT, stopHandler);
    signal(SIGTERM, stopHandler);

    UA_StatusCode retval = UA_STATUSCODE_GOOD;
    UA_ServerConfig *config = UA_ServerConfig_new_default();
    /* Details about the connection configuration and handling are located in the pubsub connection tutorial */
    config->pubsubTransportLayers = (UA_PubSubTransportLayer *) UA_malloc(sizeof(UA_PubSubTransportLayer));
    if(!config->pubsubTransportLayers) {
        UA_ServerConfig_delete(config);
        return -1;
    }
    config->pubsubTransportLayers[0] = UA_PubSubTransportLayerUDPMP();
    config->pubsubTransportLayersSize++;
    UA_Server *server = UA_Server_new(config);

    addPubSubConnection(server);
    addPublishedDataSet(server);
    addDataSetField(server);
    addWriterGroup(server);
    addDataSetWriter(server);

    retval |= UA_Server_run(server, &running);
    UA_Server_delete(server);
    UA_ServerConfig_delete(config);
    return (int)retval;
}