如何使用基于 LOB 适配器 SDK 的设计时接口答案

【问题标题】：How to consume a LOB Adapter SDK-based design-time interfaces如何使用基于 LOB 适配器 SDK 的设计时接口
【发布时间】：2014-06-30 19:17:29
【问题描述】：

我正在尝试构建一个基于 Web 的 GUI 来使用基于 LOB Adapter SDK 的自定义连接器。我特别想使用IMetadataResolverHandler接口浏览元数据。

我有两个问题：

第一个问题发生在尝试实例化自定义适配器时。我的计划是获取一个IConnectionFactory接口的实例，通过它我可以得到一个新的IConnection并连接到目标LOB系统。

由于Adapter 基类中最有趣的方法受到保护，我似乎只能使用反射来成功（请参阅下面的示例代码）。

第二个问题发生在尝试从目标系统浏览元数据时。 IMetadataResolverHandler 接口上的方法 Browse 需要一个 MetadataLookup 对象的实例，我不知道如何获得。

请看下面的示例代码：

    static void Main(string[] args)
    {
        var extension = new SqlAdapterBindingElementExtensionElement();
        var adapter = (Adapter) Activator.CreateInstance(extension.BindingElementType);

        var isHandlerSupportedMethodInfo = adapter.GetType().GetMethod("IsHandlerSupported", BindingFlags.NonPublic | BindingFlags.Instance);
        var buildConnectionUri = adapter.GetType().GetMethod("BuildConnectionUri", BindingFlags.NonPublic | BindingFlags.Instance);
        var buildConnectionFactory = adapter.GetType().GetMethod("BuildConnectionFactory", BindingFlags.NonPublic | BindingFlags.Instance);

        if (isHandlerSupportedMethodInfo == null || buildConnectionUri == null || buildConnectionFactory == null)
        {
            Console.WriteLine("Not a LOB adapter.");
            Environment.Exit(1);
        }

        var isHandlerSupportedTHandler = isHandlerSupportedMethodInfo.MakeGenericMethod(typeof(IMetadataResolverHandler));
        var isMetadataBrowseSupported = (bool)isHandlerSupportedTHandler.Invoke(adapter, new object[] { });

        if (!isMetadataBrowseSupported)
        {
            Console.WriteLine("Metadata retrieval not supported.");
            Environment.Exit(1);
        }

        var bindingElement = (SqlAdapterBindingElement)adapter;
        bindingElement.AcceptCredentialsInUri = false;
        bindingElement.InboundOperationType = InboundOperation.TypedPolling;
        bindingElement.PolledDataAvailableStatement = "EXEC [dbo].[usp_IsDataAvailable]";
        bindingElement.PollingStatement = "EXEC [dbo].[usp_SelectAvailableData]";
        bindingElement.PollingIntervalInSeconds = 10;

        var binding = new CustomBinding();
        binding.Elements.Add(adapter);

        var parameters = new BindingParameterCollection();

        var context = new BindingContext(binding, parameters);

        var credentials = new ClientCredentials();
        credentials.UserName.UserName = "username";
        credentials.UserName.Password = "password";

        var address = (ConnectionUri) buildConnectionUri.Invoke(adapter, new []{ new Uri("mssql://azure.database.windows.net//SampleDb?InboundId=uniqueId")});

        var connectionFactory = (IConnectionFactory)buildConnectionFactory.Invoke(adapter, new object[] { address, credentials, context });
        var connection = connectionFactory.CreateConnection();

        connection.Open(TimeSpan.MaxValue);

        MetadataLookup lookup = null; // ??
        var browser = connection.BuildHandler<IMetadataBrowseHandler>(lookup);

        connection.Close(TimeSpan.MaxValue);
    }

【问题讨论】：

标签： wcf-lob-adapter

【解决方案1】：

回答我自己的问题时，我通过检查“使用适配器服务”向导的代码找到了答案。关键是使用IMetadataRetrievalContract 接口，该接口在内部使用最多三个LOB-SDK 接口实现，尤其是IMetadataResolverHandler。

这是无需反射即可工作的代码：

var extension = new SqlAdapterBindingElementExtensionElement();
var adapter = (Adapter) Activator.CreateInstance(extension.BindingElementType);

var bindingElement = (SqlAdapterBindingElement)adapter;
bindingElement.AcceptCredentialsInUri = false;
bindingElement.InboundOperationType = InboundOperation.TypedPolling;
bindingElement.PolledDataAvailableStatement = "EXEC [dbo].[usp_IsDataAvailable]";
bindingElement.PollingStatement = "EXEC [dbo].[usp_SelectAvailableData]";
bindingElement.PollingIntervalInSeconds = 10;

var binding = new CustomBinding();
binding.Elements.Add(adapter);

const string endpoint = "mssql://azure.database.windows.net//SampleDb?InboundId=unique";
var factory = new ChannelFactory<IMetadataRetrievalContract>(binding, new EndpointAddress(new Uri(endpoint)));
factory.Credentials.UserName.UserName = "username";
factory.Credentials.UserName.Password = "password";

factory.Open();
var channel = factory.CreateChannel();
((IChannel)channel).Open();

var metadata = channel.Browse(MetadataRetrievalNode.Root.DisplayName, 0, Int32.MaxValue);

((IChannel) channel).Close();
factory.Close();

【讨论】：