OPC客户端分析 —

上篇给大家分析了如何在客户端进行服务器查询，今天再分析下在客户端的读和写的操作。下面这个函数囊括各路类型的读写操作，如异步或同步等等，实用性很强。

HRESULT synReadOrWrite(serverGroup* serverGroup, bool read, bool async) {char *buffer = (char *)malloc(MAXBYTE);OPCITEMRESULT *pResults = NULL;OPCHANDLE *hServerItem = NULL;HRESULT hResult = S_OK;IOPCSyncIO *pIOPCSyncIO = NULL;IOPCAsyncIO2 *pIOPCAsyncIO2 = NULL;if (async) {if (serverGroup->groupInfo->ipCPC == NULL) {hResult = buildCallback(serverGroup);if (FAILED(hResult)) {_tprintf(_T("Failed in buildCallback.\n"));return hResult;}}hResult = serverGroup->groupInfo->ipMgt->QueryInterface(IID_IOPCAsyncIO2, (void**)&pIOPCAsyncIO2);showConsole = false;}elsehResult = serverGroup->groupInfo->ipMgt->QueryInterface(IID_IOPCSyncIO, (void**)&pIOPCSyncIO);HRESULT *pErrors = NULL;if (FAILED(hResult)){_tprintf(_T("getting interface IID_IOPCSyncIO or IID_IOPCAsyncIO2 failed.\r\n"));goto end;}if (read) {_tprintf(_T("Enter tag names seperated by comma and press enter: "));fgets(buffer, MAXBYTE, stdin);size_t ln = strlen(buffer) - 1;if (buffer[ln] == '\n')buffer[ln] = '\0';char **result = NULL;size_t dwCount = 0;OPCITEMSTATE *pValues = NULL;if (strlen(buffer) == 0) {_tprintf(_T("tag names should be in format like this - tagName1, tagName2, tagName3\n"));hResult = E_INVALIDARG;goto end;}tokenizeString(buffer, ',', (char***)&result, &dwCount);pResults = (OPCITEMRESULT*)CoTaskMemAlloc(dwCount * sizeof(OPCITEMRESULT));hServerItem = (OPCHANDLE *)CoTaskMemAlloc(dwCount * sizeof(OPCHANDLE));pErrors = (HRESULT *)CoTaskMemAlloc(dwCount * sizeof(HRESULT));hResult = addItems(serverGroup->groupInfo->ipMgt, result, &pResults, &pErrors, dwCount);for (DWORD ii = 0; ii < dwCount; ii++) {if (!pErrors[ii])hServerItem[ii] = pResults[ii].hServer;}if (async) {DWORD dwCancelID;hResult = pIOPCAsyncIO2->Read(dwCount, hServerItem, *hServerItem, &dwCancelID, &pErrors); /* *hServerItem as transactionID*/}elsehResult = pIOPCSyncIO->Read(OPC_DS_DEVICE, dwCount, hServerItem, &pValues, &pErrors);if (FAILED(hResult) || hResult == S_FALSE){_com_error err(hResult);LPCTSTR errMsg = err.ErrorMessage();_tprintf(_T("Read failed: %s\r\n"), errMsg);for (DWORD ii = 0; ii < dwCount; ii++) {if (pErrors && pErrors[ii]) {if (pErrors[ii] == OPC_E_INVALIDHANDLE) {_tprintf(_T("element with index [%d] is invalid\n"), ii);}else{_com_error err(pErrors[ii]);errMsg = err.ErrorMessage();_tprintf(_T("Reading element with index [%d] failed: %s\n"), ii, errMsg);}}else{if (!async) {VARIANT vValue;VariantInit(&vValue);if (SUCCEEDED(VariantChangeType(&vValue, &pValues[ii].vDataValue, NULL, VT_BSTR))) {clientNode* tmpNode = findNode(true, hServerItem[ii]);_tprintf(_T("syncoReadWrite Read: %S %S\r\n"), tmpNode->clientName, vValue.bstrVal);}VariantClear(&vValue);}}}}else if (!async){for (DWORD ii = 0; ii < dwCount; ii++){VARIANT vValue;VariantInit(&vValue);if (SUCCEEDED(VariantChangeType(&vValue, &pValues[ii].vDataValue, NULL, VT_BSTR))) {clientNode* tmpNode = findNode(true, hServerItem[ii]);_tprintf(_T("syncoReadWrite Read: %S %S\r\n"), tmpNode->clientName, vValue.bstrVal);}VariantClear(&vValue);}}for (size_t i = 0; i < dwCount; i++) {if (!async)freeNode(hServerItem[i]);free(*(result + i));}free(result);if (!async)hResult = serverGroup->groupInfo->ipMgt->RemoveItems(dwCount, hServerItem, &pErrors);CoTaskMemFree(pValues);}else{_tprintf(_T("Enter tag name and value seperated by comma, and delimit them in semicolon: "));fgets(buffer, MAXBYTE, stdin);size_t ln = strlen(buffer) - 1;if (buffer[ln] == '\n')buffer[ln] = '\0';char **result = NULL, **nameValuePair = NULL, **names = NULL, **values = NULL;size_t dwCount = 0;if (strlen(buffer) == 0) {_tprintf(_T("tag name/value pair should be in format like this - tagName1, tagValue1; tagName2, tagValue2; tagName3, tagValue3\n"));hResult = E_INVALIDARG;goto end;}tokenizeString(buffer, ';', (char***)&result, &dwCount);names = (char**)malloc(sizeof(void*)*dwCount);values = (char**)malloc(sizeof(void*)*dwCount);for (DWORD ii = 0; ii < dwCount; ii++) {names[ii] = NULL;values[ii] = NULL;}size_t count = 0;for (DWORD ii = 0; ii < dwCount; ii++) {tokenizeString(result[ii], ',', (char***)&nameValuePair, &count);if (count == 2) {names[ii] = nameValuePair[0];values[ii] = nameValuePair[1];}else{_tprintf(_T("tag name and value should be paired. Check your input.\n"));for (size_t i = 0; i < dwCount; i++) {free(names[i]);free(values[i]);free(result[i]);}free(nameValuePair);free(names);free(values);free(result);goto end;}count = 0;}pResults = (OPCITEMRESULT*)CoTaskMemAlloc(dwCount * sizeof(OPCITEMRESULT));hServerItem = (OPCHANDLE *)CoTaskMemAlloc(dwCount * sizeof(OPCHANDLE));pErrors = (HRESULT *)CoTaskMemAlloc(dwCount * sizeof(HRESULT));hResult = addItems(serverGroup->groupInfo->ipMgt, names, &pResults, &pErrors, dwCount);for (DWORD ii = 0; ii < dwCount; ii++) {if (!pErrors[ii])hServerItem[ii] = pResults[ii].hServer;}VARIANT *varValue = (VARIANT *)CoTaskMemAlloc(dwCount * sizeof(VARIANT));for (DWORD ii = 0; ii < dwCount; ii++){if (!pErrors[ii]){varValue[ii].vt = VT_R4;varValue[ii].fltVal = strtof(values[ii], NULL);}}if (async) {DWORD dwCancelID;hResult = pIOPCAsyncIO2->Write(dwCount, hServerItem, varValue, *hServerItem, &dwCancelID, &pErrors); /* *hServerItem as transactionID */}elsehResult = pIOPCSyncIO->Write(dwCount, hServerItem, varValue, &pErrors);if (FAILED(hResult) || hResult == S_FALSE){_com_error err(hResult);LPCTSTR errMsg = err.ErrorMessage();_tprintf(_T("Write failed: %s\r\n"), errMsg);for (DWORD ii = 0; ii < dwCount; ii++){if (pErrors && pErrors[ii]) {if (pErrors[ii] == OPC_E_INVALIDHANDLE)_tprintf(_T("element with index [%d] is invalid\n"), ii);else {_com_error err(pErrors[ii]);errMsg = err.ErrorMessage();_tprintf(_T("Writing element with index [%d] failed: %s\n"), ii, errMsg);}}}}else{_tprintf(_T("Writing is successful.\n"));}if (!async)hResult = serverGroup->groupInfo->ipMgt->RemoveItems(dwCount, hServerItem, &pErrors);CoTaskMemFree(varValue);for (size_t i = 0; i < dwCount; i++) {if (!async)freeNode(hServerItem[i]);free(names[i]);free(values[i]);free(*(result + i));}free(names);free(values);free(result);}end:free(buffer);CoTaskMemFree(pResults);CoTaskMemFree(hServerItem);CoTaskMemFree(pErrors);if (pIOPCSyncIO)pIOPCSyncIO->Release();if (pIOPCAsyncIO2)pIOPCAsyncIO2->Release();return hResult;
}

程序比较长，大致的结构是这样的。根据传入的是否异步的值，从获得的OPC服务端的实例中取得执行IID_IOPCAsyncIO2（异步）或者IID_IOPCSyncIO（同步）的实例位置，如果是异步还需先告诉OPC服务器你的回调函数是什么，在这里是buildCallback(), 具体程序见下。根据传入的读写值来处理。先进行读的处理，根据异同步分别处理；然后是写的处理，也分异同步进行。当中也有一些辅助函数，我就不一一例举了，有需要的和我联系我再在这里贴出来。客户端打算告一段落，下篇讲讲服务端的安全问题。

HRESULT buildCallback(serverGroup *serverGroup) {HRESULT hResult = S_OK;hResult = serverGroup->groupInfo->ipMgt->QueryInterface(IID_IConnectionPointContainer, (void**)&serverGroup->groupInfo->ipCPC);if (FAILED(hResult)){_tprintf(_T("QueryInterface for IConnectionPointContainer failed.\r\n"));return hResult;}IConnectionPoint* ipCP = NULL;hResult = serverGroup->groupInfo->ipCPC->FindConnectionPoint(IID_IOPCDataCallback, &ipCP);if (FAILED(hResult)){_tprintf(_T("FindConnectionPoint failed.\r\n"));return hResult;}// create the callback object.Callback* ipCallback = new Callback();DWORD dwAdvise;hResult = ipCP->Advise(ipCallback, &dwAdvise);if (FAILED(hResult)){_tprintf(_T("Advise failed.\r\n"));return hResult;}return hResult;
}

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