我们有两个 Web 服务在 IIS7 的不同应用程序池上运行。Web 服务是相同的,不同的是一个连接到测试数据库,另一个连接到实时数据库。
Web 服务需要一个用 Delphi 编写的 DLL 来生成系统所需的一些业务逻辑,我们使用动态 DLL 加载来加载这些逻辑,如下所示:
public static class DynamicLinking
{
private static int libHandle;
private static string dllName;
public static void init(String pDllName)
{
dllName = pDllName;
libHandle = LoadLibrary(pDllName);
}
public static void fini()
{
FreeLibrary(libHandle);
}
[DllImport("kernel32.dll", EntryPoint = "LoadLibrary")]
static extern int LoadLibrary([MarshalAs(UnmanagedType.LPStr)] string lpLibFileName);
[DllImport("kernel32.dll", EntryPoint = "GetProcAddress")]
static extern IntPtr GetProcAddress(int hModule, [MarshalAs(UnmanagedType.LPStr)] string lpProcName);
[DllImport("kernel32.dll", EntryPoint = "FreeLibrary")]
static extern bool FreeLibrary(int hModule);
[UnmanagedFunctionPointer(CallingConvention.StdCall, CharSet = CharSet.Ansi)]
delegate bool QryFunction(string domainString, string qryString,
int outputStringBufferSize, ref string outputStringBuffer);
public static void ExecuteDLLFunction(string pfunctionName, int bufferSize,
string pDomain, string inputXMLString,
out string outputString)
{
if (libHandle == 0)
throw new Exception(string.Format("Could not load library \"{0}\"", dllName));
var delphiFunctionAddress = GetProcAddress(libHandle, pfunctionName);
if (delphiFunctionAddress == IntPtr.Zero)
throw new Exception(string.Format("Can't find function \"{0}\" in library \"{1}\"", pfunctionName, dllName));
var queryFunction = (QryFunction)Marshal.GetDelegateForFunctionPointer(delphiFunctionAddress, typeof(QryFunction));
var outputStringBuffer = new String('\x00', bufferSize);
var errorMsgBuffer = new String('\x00', bufferSize);
if (!queryFunction(pDomain, inputXMLString,
bufferSize, ref outputStringBuffer))
throw new Exception(errorMsgBuffer);
outputString = outputStringBuffer;
}
}
现在问题出在此处:当我们启动网络时,最后启动的网站将无法加载 dll,而第一个加载的网站将运行良好。
//edit------------------------------------ 奇怪的是,当每个网站复制同一个DLL时,这个然而,问题出现了,如果我们将两个站点链接到同一个 DLL,一切正常
对此有何见解?