[系统运维]学习open62541 --- [59] 遍历Server所有node

Client端有个api叫UA_Client_Service_browse，可以遍历Server里指定node下所有的直接子node，其原型如下，

static UA_INLINE UA_BrowseResponse
UA_Client_Service_browse(UA_Client *client, const UA_BrowseRequest request);

一 例子

先准备个Server代码，如下，

#include "open62541.h"

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

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_Server *server = UA_Server_new();
    UA_ServerConfig_setDefault(UA_Server_getConfig(server));
    
    UA_StatusCode retval = UA_Server_run(server, &running);
	
    UA_Server_delete(server);
    
    return retval == UA_STATUSCODE_GOOD ? EXIT_SUCCESS : EXIT_FAILURE;
}

下面是client代码，程序遍历Objects目录，

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

int main(void) 
{
    UA_Client *client = UA_Client_new();
    UA_ClientConfig_setDefault(UA_Client_getConfig(client));
    UA_StatusCode retval = UA_Client_connect(client, "opc.tcp://localhost:4840");
    if(retval != UA_STATUSCODE_GOOD) {
        UA_Client_delete(client);
        return (int)retval;
    }
    

	/* Browse some objects */
    printf("Browsing nodes in objects folder:\n");
	
    UA_BrowseRequest bReq;
    UA_BrowseRequest_init(&bReq); // 初始化bReq
    bReq.requestedMaxReferencesPerNode = 0;
    bReq.nodesToBrowse = UA_BrowseDescription_new(); // 分配内存，并把地址赋给bReq.nodesToBrowse
    bReq.nodesToBrowseSize = 1; // 遍历的起始节点数量
    bReq.nodesToBrowse[0].nodeId = UA_NODEID_NUMERIC(0, UA_NS0ID_OBJECTSFOLDER); // 遍历 objects目录
    bReq.nodesToBrowse[0].resultMask = UA_BROWSERESULTMASK_ALL; // 返回所有
    
    UA_BrowseResponse bResp = UA_Client_Service_browse(client, bReq); // 开始遍历
	if (bResp.responseHeader.serviceResult) // 判断遍历结果
	{
		// 打印遍历结果
		printf("%-9s %-16s %-16s %-16s\n", "NAMESPACE", "NODEID", "BROWSE NAME", "DISPLAY NAME");
		for(size_t i = 0; i < bResp.resultsSize; ++i) {
			for(size_t j = 0; j < bResp.results[i].referencesSize; ++j) {
				UA_ReferenceDescription *ref = &(bResp.results[i].references[j]);
				if(ref->nodeId.nodeId.identifierType == UA_NODEIDTYPE_NUMERIC) {
					printf("%-9d %-16d %-16.*s %-16.*s\n", ref->nodeId.nodeId.namespaceIndex,
						   ref->nodeId.nodeId.identifier.numeric, (int)ref->browseName.name.length,
						   ref->browseName.name.data, (int)ref->displayName.text.length,
						   ref->displayName.text.data);
				} else if(ref->nodeId.nodeId.identifierType == UA_NODEIDTYPE_STRING) {
					printf("%-9d %-16.*s %-16.*s %-16.*s\n", ref->nodeId.nodeId.namespaceIndex,
						   (int)ref->nodeId.nodeId.identifier.string.length,
						   ref->nodeId.nodeId.identifier.string.data,
						   (int)ref->browseName.name.length, ref->browseName.name.data,
						   (int)ref->displayName.text.length, ref->displayName.text.data);
				}
				/* TODO: distinguish further types */
			}
		}
	}
    

    UA_BrowseRequest_clear(&bReq);
    UA_BrowseResponse_clear(&bResp);


    
    /* Clean up */
    UA_Client_delete(client); /* Disconnects the client internally */
    
    return EXIT_SUCCESS;
}

最终打印如下，

可以看出只能遍历Objects目录下的所有直接子node，那么如何遍历间接的node呢？就是再遍历读取到的直接node，好像有点傻…

二 相关结构体

结构体UA_BrowseRequest的定义如下，用来发送遍历请求，可以同时遍历多个节点

/**
 * BrowseRequest
 * ^^^^^^^^^^^^^
 * Browse the references for one or more nodes from the server address space. */
typedef struct {
    UA_RequestHeader requestHeader;
    UA_ViewDescription view;
    UA_UInt32 requestedMaxReferencesPerNode;
    size_t nodesToBrowseSize; // 需要遍历的起始节点数目
    UA_BrowseDescription *nodesToBrowse; // 起始节点描述
} UA_BrowseRequest;