Exploring nanopb client server example and trying with other protobuf library. My question is : Is nanopb generated protobuf compatible with protobuf generated in other language like java using google's protobuf-java ? protobuf encoded in nanopb can be decoded by google protobuf library in java and vice versa? I encountered a problem in socket communication between C protobuf client and Java Protobuf server. C client code follows nanopb network_server example, client server sharing same proto message. C client and C server is working fine , similarly Java client and Java Server is also working fine. However when C client connects to Netty TCP server it is not showing any output.
message Sample {
optional string value = 1;
}
options has max_size defined.
C client code snippet :
Sample message = Sample_init_default;
pb_ostream_t stream = pb_ostream_from_buffer(buffer, sizeof(buffer));
strcpy(message.value,"device1");
status = pb_encode(&stream, Sample_fields, &message);
message_length = stream.bytes_written;
if (!status)
{
printf("Encoding failed: %s\n", PB_GET_ERROR(&stream));
return 1;
}
pb_ostream_t output = pb_ostream_from_socket(sockfd);
if (!pb_encode_delimited(&output, Sample_fields, &message))
{
printf("Encoding failed: %s\n", PB_GET_ERROR(&output));
}
Java TCP Server (Netty based ) snippet :
// main calls run method
public void run() {
EventLoopGroup ServerGroup = new NioEventLoopGroup();
try{
ServerBootstrap bootstrap = new ServerBootstrap();
bootstrap.group(ServerGroup)
.channel(NioServerSocketChannel.class)
.option(ChannelOption.SO_BACKLOG, 100)
.childHandler(new ServerInitializer());
ChannelFuture future = bootstrap.bind(1234).sync();
future.channel().closeFuture().sync();
} catch(Exception ex) {
System.out.println(ex);
}
finally{
System.out.println("Logging Off");
ServerGroup.shutdownGracefully();
}
}
public class ServerInitializer extends ChannelInitializer<SocketChannel> {
@Override
public void initChannel(SocketChannel ch) throws Exception {
try {
ChannelPipeline p = ch.pipeline();
//add decoders and encoders
p.addLast(new ProtobufVarint32FrameDecoder());
p.addLast(new ProtobufDecoder(SampleProtos.Sample.getDefaultInstance()));
p.addLast(new ProtobufVarint32LengthFieldPrepender());
p.addLast(new ProtobufEncoder());
//handler for business logic
p.addLast(new ServerHandler());
} catch (Exception ex) {
System.out.println(ex);
}
}
}
public class ServerHandler extends ChannelInboundHandlerAdapter {
.........
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
System.out.println("Channel Read...");
try {
SampleProtos.Sample sample = (SampleProtos.Sample)msg;
System.out.println("Value Read: " + sample.getValue());
sample = sample.toBuilder().setValue("Server Response").build();
ctx.writeAndFlush(sample);
} catch (Exception ex){
System.out.println(ex);
}
}
}
The server output is blank for C client but shows client sent data for Java Netty client. Any suggestion why my code is failing? Thanks in anticipation.
