Using ByteArrayLengthHeaderSerializer with java.net.Socket client - spring

Question

I am trying to connect a simple java.net.Socket TCP client to a Spring Integration TCP server using a ByteArrayLengthHeaderSerializer.
Here is the relevant client code snippet:
Socket socket = null;
OutputStream out = null;
InputStream in = null;
try {
socket = new Socket(host, port);
out = new BufferedOutputStream(socket.getOutputStream());
in = new BufferedInputStream(socket.getInputStream());
byte[] lengthBuf = new byte[4];
int size = in.read(lengthBuf, 0, lengthBuf.length);
ByteArrayInputStream bis = new ByteArrayInputStream(lengthBuf);
ObjectInputStream ois = new ObjectInputStream(bis);
int dataSize = ois.readInt();
System.out.println("Got size: " + dataSize);
byte[] dataBuffer = new byte[dataSize];
int dataRead = in.read(dataBuffer, 0, dataBuffer.length);
bis = new ByteArrayInputStream(dataBuffer);
ois = new ObjectInputStream(bis);
String data = (String) ois.readObject();
System.out.println("read " + dataRead + " bytes, got data: " + data);
Here is the server side configuration:
#MessagingGateway(defaultRequestChannel="toTcp")
public interface Gateway {
void send(#Payload byte[] data, #Header(IpHeaders.CONNECTION_ID) String connectionId);
}
#Bean
public AbstractServerConnectionFactory serverFactory() {
AbstractServerConnectionFactory connectionFactory = new TcpNetServerConnectionFactory(port);
ByteArrayLengthHeaderSerializer serDeser = new ByteArrayLengthHeaderSerializer();
connectionFactory.setSerializer(serDeser);
connectionFactory.setDeserializer(serDeser);
return connectionFactory;
}
#Bean
public TcpReceivingChannelAdapter inboundAdapter(AbstractServerConnectionFactory connectionFactory) {
TcpReceivingChannelAdapter inbound = new TcpReceivingChannelAdapter();
inbound.setConnectionFactory(connectionFactory);
inbound.setOutputChannel(fromTcp());
return inbound;
}
and the calling code:
public void send(String data, String header) throws IOException {
ByteArrayOutputStream bos = new ByteArrayOutputStream();
try (ObjectOutputStream oos = new ObjectOutputStream(bos)) {
System.out.println("data.length is " + data.length());
oos.writeObject(data);
byte[] bytes = bos.toByteArray();
gateway.send(bytes, header);
}
}
When I send the data (e.g. 'abc') I get (on the client side) this error:
invalid stream header: 0000000A
On the server side I get:
SoftEndOfStreamException: Stream closed between payloads
What am I doing wrong?

Answer 1

No - an ObjectOutputStream serializes java objects (and the input stream deserializes). You don't need a length header deserializer for that, just use a DefaultSerializer and DefaultDeserializer (from Spring Core) and don't add the header.
You are getting the error because the serialization adds more stuff at the beginning.
Or, if you are only sending a String, you can use String.getBytes() and send the length (4 bytes) followed by the byte[].