c# - Web API/WCF 如何保持对象存活

Question

我有一个引擎(ABBYY FlexiCapture 引擎)，我想将它与 REST 服务(WebAPI 或 WCF)一起使用。发动机启动初始化需要 30 秒。每个请求都太长了。我希望引擎加载服务启动并保持在“预热”状态。我怎样才能用 WebAPI 或 WCF 做到这一点？ (最好的方法是保持线程与引擎保持事件状态)。PS:抱歉我的英语不好。

-- 来自 ABBYY 范例库

private void ProcessImages()
        {
            trace("Loading FlexiCapture Engine...");
            IEngine engine = LoadEngine();
            try
            {
                string samplesFolder = FceConfig.GetSamplesFolder();

                trace("Creating and configuring the FlexiCapture Processor...");
                IFlexiCaptureProcessor processor = engine.CreateFlexiCaptureProcessor();
                processor.AddDocumentDefinitionFile(samplesFolder + "\\SampleProject\\Templates\\Invoice_eng.fcdot");
                // ....

                trace("Adding images to process...");
                processor.AddImageFile(samplesFolder + "\\SampleImages\\Invoices_1.tif");
                // ....

                trace("Recognizing the images and exporting the results...");

                while (true)
                {
                    // Recognize next document
                    IDocument document = processor.RecognizeNextDocument();
                    // processing recognized document...
                }
            }
            finally
            {
                UnloadEngine(ref engine);
            }
        }

        private IEngine LoadEngine()
        {
            // FlexiCapture Engine can be loaded in three diffrent ways:
            // 1) Directly, as in this sample
            // 2) As an inproc server (using COM infrastructure)
            // 3) As an out-of-proc server in a worker process (using COM infrastructure)

            IEngine engine;
            int hResult = InitializeEngine(FceConfig.GetDeveloperSN(), null, null, out engine);
            Marshal.ThrowExceptionForHR(hResult);
            return engine;
        }

我想创建引擎。之后，我将创建和配置多个 FlexiCapture 处理器。 (需要很长时间，我想在服务启动时做)然后，当用户添加图像时 - 我将使用其中一个处理器来识别它们。

启动时:创建引擎 -> 创建多个处理器(+配置它们)；在方法调用上:选择一个免费处理器 -> 识别用户图像。

Answer 1

也许，您需要实现引擎的静态单例实例并使用上下文

[ServiceBehavior(ConcurrencyMode = ConcurrencyMode.Multiple, InstanceContextMode = InstanceContextMode.Single)]
public static class EngineContainer
{
    private static Engine _engine { get; set; }
    public static Engine GetEngine 
    {
        get { if (_engine == null) Init(); return _engine; }
    }
}