解决跨平台使用时的请求-响应问题（C# 和 JAVA）

Question

我正在尝试在 Solace 中实现请求-响应。

但是 RR-Requestor 是用 C# 编写的，而 RR-Responder 的代码是用 JAVA 编写的。

我有 2 个问题：

1. Solace C# API 成功发送消息后，它会被 JAVA 应用程序接收。我碰巧收到了 BytesXMLMessage 结构中的消息。 如何将消息转换为字符串？ message.dump() 给了我全部的细节。

2. 当我发送回复消息时，.NET 应用程序会收到带有一些额外不需要的字符的消息。

JAVA端使用的代码：

    //After session is created
    XMLMessageConsumer consumer = session.getMessageConsumer(new RequestHandler());
    XMLMessageProducer producer = session.getMessageProducer(new PrintingPubCallback());
    consumer.start();
    session.addSubscription(
            JCSMPFactory.onlyInstance().createTopic("Test_Response_Queue"),
            true);
    class RequestHandler implements XMLMessageListener {

    private void sendReply(BytesXMLMessage request, BytesXMLMessage reply)
            throws JCSMPException {

        producer.sendReply(request, reply);

    }

    public void onException(JCSMPException arg0) {
        // TODO Auto-generated method stub

    }

    public void onReceive(BytesXMLMessage message) {
        System.out.println("Received request message, trying to parse it");

        System.out.println(message.dump());

        try {

            TextMessage textMessage = JCSMPFactory.onlyInstance()
                    .createMessage(TextMessage.class);

            final String text = "Reply from JAVA, text message!!";
            textMessage.setText(text);

            sendReply(message, textMessage);

        } catch (JCSMPException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }

在 .NET 方面

            // Create the request message
        IMessage requestMessage = ContextFactory.Instance.CreateMessage();
        requestMessage.Destination = ContextFactory.Instance.CreateTopic("Test_Response_Queue");
        requestMessage.DeliveryMode = MessageDeliveryMode.Direct; /* explicitly set to MessageDeliveryMode.Direct */
        //IStreamContainer stream = SDTUtils.CreateStream(requestMessage, 256);
        //stream.AddString("Hello from Linux!!");
        requestMessage.BinaryAttachment = Encoding.ASCII.GetBytes("Hello from Linux!!");

        // Send the request message to the service or RRDirectReplier
        IMessage replyMessage = null;
        int timeout = 2000; /* 2 secs*/
        Console.WriteLine("\nSending  request message, waiting for {0} msecs for a reply (make sure that RRDirectReply is running) ...", timeout);

        if (session.SendRequest(requestMessage, out replyMessage, 2000) == ReturnCode.SOLCLIENT_OK)
        {
            // Got a reply, format and print the response message
            Console.WriteLine("\nGot reply message");
            String str = Encoding.ASCII.GetString(replyMessage.BinaryAttachment);
            Console.WriteLine(str);
        }
        else
        {
            Console.WriteLine("Request failed");
        }
        if (requestMessage != null)
        {
            // It is a good practice to dispose of messages once done using them
            requestMessage.Dispose();
        }

回复在收到的字符串中包含其他字符。 见下图。

有什么想法吗？

谢谢。

Answer 1

有几种方法可以在不同 API 之间发送/接收字符串，这里有 2 种可能的方法。

1。将字符串转换为字节数组，并将其作为二进制有效负载附加到 Solace 消息中。

.NET 发送：

IMessage message = ContextFactory.Instance.CreateMessage();
message.Destination = topic;
message.BinaryAttachment = Encoding.UTF8.GetBytes("My .NET String");
session.Send(message);

Java 接收：

// assuming that message is a reference to a received message
if(message.getAttachmentByteBuffer() != null) {
    byte[] messageBinaryPayload = message.getAttachmentByteBuffer().array();
    try {
        String myReceivedText = new String(messageBinaryPayload, "UTF-8");
        System.out.println("Received String = " + myReceivedText);
    } catch (UnsupportedEncodingException e) {
        e.printStackTrace();
    }
}
else {
    // No binary attachment in message - application needs to decide what to do next.
}

Java 发送：

String myJavaString = "My Java String";
BytesXMLMessage message = JCSMPFactory.onlyInstance().createMessage(BytesXMLMessage.class);
message.writeAttachment(myJavaString.getBytes(Charset.forName("UTF-8")));
producer.send(message, topic);

.NET 接收：

// assuming that message is a reference to a received message
byte[] messageBinaryPayload = message.BinaryAttachment;

if(messageBinaryPayload != null) {
    string myReceivedString = System.Text.Encoding.UTF8.GetString(messageBinaryPayload);
    Console.WriteLine("Received String = " + myReceivedString);
}
else {
    // No binary attachment in message - application needs to decide what to do next.
}

2。以 TextMessage 形式发送和接收字符串

.NET 发送：

IMessage message = ContextFactory.Instance.CreateMessage();
message.Destination = topic;
SDTUtils.SetText(message, "My .NET String");
session.Send(message);

Java 接收：

// assuming that message is a reference to a received message
if (message instanceof TextMessage) {
    String myReceivedString = ((TextMessage) message).getText();
    System.out.println("Received String = " + myReceivedString);
} 
else {
    // Message is not a TextMessage - application needs to decide what to do next.
}

Java 发送：

TextMessage message = JCSMPFactory.onlyInstance().createMessage(TextMessage.class);
message.setText("My Java String");
producer.send(message, topic);

.NET 接收：

// assuming that message is a reference to a received message
String myReceivedString = SDTUtils.GetText(message);
if (myReceivedString != null) {
    // Message is an TextMessage
    Console.WriteLine("Received String = " + myReceivedString);
}
else {
    // Message is not a TextMessage - application needs to decide what to do next.
}

Answer 2

如果您收到的消息是文本消息，请尝试以下操作：

if (message instanceof TextMessage) {
    String text = ((TextMessage) message).getText();
} 
//otherwise retrieve the attachment buffer like this
else {
    byte[] body = message.getAttachmentByteBuffer().array();
    //and convert to String
    String text = new String(body);
}

您可能会在回复消息的开头看到一个额外的字符，因为您正在创建一个 TextMessage 作为回复。 TextMessage 在附件的开头包含一些额外的字节以将其标记为 TextMessage 并且那些包含文本的长度。您应该在 .NET 中使用相应的类，例如为您进行解析的 TextMessage。