--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/goodjava/rpc/RpcCon.java	Tue Sep 17 01:35:01 2019 -0400
@@ -0,0 +1,132 @@
+package goodjava.rpc;
+
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.io.IOException;
+import java.io.EOFException;
+import java.net.Socket;
+import java.nio.charset.StandardCharsets;
+import java.util.List;
+import goodjava.parser.ParseException;
+import goodjava.json.JsonParser;
+import goodjava.json.JsonToString;
+
+
+public class RpcCon {
+	final Socket socket;
+	final InputStream in;
+	final OutputStream out;
+	InputStream inBinary = null;
+	long lenBinary = -1;
+	boolean readSome = false;
+
+	RpcCon(Socket socket)
+		throws RpcError
+	{
+		try {
+			this.socket = socket;
+			this.in = socket.getInputStream();
+			this.out = socket.getOutputStream();
+		} catch(IOException e) {
+			close();
+			throw new RpcError(e);
+		}
+	}
+
+	public void close()
+		throws RpcError
+	{
+		try {
+			socket.close();
+		} catch(IOException e) {
+			throw new RpcError(e);
+		}
+	}
+
+	public boolean isClosed() {
+		return socket.isClosed();
+	}
+
+	void write(InputStream in,long lenIn,List list)
+		throws RpcError
+	{
+		if( in != null )
+			list.add(0,lenIn);
+		String json = JsonToString.toString(list);
+		byte[] aJson = json.getBytes(StandardCharsets.UTF_8);
+		int len = aJson.length;
+		byte[] a = new byte[4+len];
+        a[0] = (byte)(len >>> 24);
+        a[1] = (byte)(len >>> 16);
+        a[2] = (byte)(len >>>  8);
+        a[3] = (byte)(len >>>  0);
+		System.arraycopy(aJson,0,a,4,len);
+		try {
+			out.write(a);
+			if( in != null ) {
+				a = new byte[8192];
+				long total = 0;
+				int n;
+				while( (n=in.read(a)) != -1 ) {
+					out.write(a,0,n);
+					total += n;
+				}
+				if( total != lenIn ) {
+					close();
+					throw new RpcError("InputStream wrong length "+total+" when should be "+lenIn);
+				}
+			}
+		} catch(IOException e) {
+			close();
+			throw new RpcError(e);
+		}
+	}
+
+	List readJson()
+		throws RpcError
+	{
+		try {
+			if( inBinary != null ) {
+				inBinary.close();
+				inBinary = null;
+				lenBinary = -1;
+			}
+			readSome = false;
+			byte[] a = new byte[4];
+			readAll(a);
+			int len = 0;
+			for( byte b : a ) {
+				len <<= 8;
+				len |= b&0xFF;
+			}
+			a = new byte[len];
+			readAll(a);
+			String json = new String(a,StandardCharsets.UTF_8);
+			List list = (List)JsonParser.parse(json);
+			if( list.get(0) instanceof Long ) {
+				lenBinary = (Long)list.remove(0);
+				inBinary = new FixedLengthInputStream(in,lenBinary);
+			}
+			return list;
+		} catch(IOException e) {
+			close();
+			throw new RpcError(e);
+		} catch(ParseException e) {
+			close();
+			throw new RpcError(e);
+		}
+	}
+
+	private void readAll(final byte[] a) throws IOException {
+		int total = 0;
+		int n;
+		while( total < a.length ){
+			n = in.read( a, total, a.length-total );
+			if( n == -1 )
+				throw new EOFException();
+			readSome = true;
+			total += n;
+		}
+	}
+
+}