It doesn't matter what kind of stream you use. Protobufs just read and write bytes. You'll get the exact same result with any kind of stream.
On Wed, Dec 2, 2009 at 12:13 PM, Nigel Pickard <[email protected]>wrote: > Thanks for the reply Adam -I did a simple sub into my code with your > suggestion, but it doesn't work. However, now it's made me think of > more questions..... > > If protocol buffers doesn't use object I/O streams, which streams does > it use? The argument in Java simply asks for an OutputStream > argument, and of course that could mean File, ByteArray, Object, Data, > etc.... > > And perhaps more importantly, will the choice of Java stream types > impact how GPB objects may be reconstituted in C++? At the simplest > level I assume this can be done: > > I can create a GPB class called "GPBCar". > I have an outputstream (of some type, not sure!) over a socket in Java > I want to write to. > After creating my GPBCar object, I use the GPB "writeTo(output)" > method on the Java side. > My C++ app takes some form of this byte stream and reconstitutes my > GPBCar instance by using the equivalent of the "parseFrom" method from > the GPBCar. > > My understanding is that I have converted my GPBCar to a series of > bytes that represent that GPBCar instance. Now I have a C++ app at the > other end of the socket connection. But will the series of bytes be > in the correct order (endianness?). Will the outputstream type be > particular to Java, or will I encounter problems by using certain > specific Java outputstreams? Should I only be using the > CodedDataOutputStream provided by GPB? (I note that there is > implementations of this stream in both the C++ and Java GPB > implementations). > > I should add I've tried to find answers to these questions on the > board and web, but with no luck. Again, if anyone has a simple > example of how they used GPB to communicate over a socket from a Java > to a C++ app, I'd love to see it (or just point me in the right > direction). > > > On Dec 2, 1:14 pm, Adam Vartanian <[email protected]> wrote: > > > > Protocol buffer code doesn't use object streams, so when you pass one > > to its writeTo/parseFrom methods, you're actually passing the object > > stream as a regular OutputStream or InputStream, ie, your code is > > already serializing to and from bytes. If you'd rather be explicit > > about it, you can just switch your stream's type from > > ObjectOutputStream to OutputStream (similarly with Input) and it > > should continue to work the same. All that should require is instead > > of doing something like > > > > ObjectOutputStream output = new > ObjectOutputStream(socket.getOutputStream()); > > message.writeTo(output); > > > > you do something like > > > > OutputStream output = socket.getOutputStream(); > > message.writeTo(output); > > > > For interacting with C++, you should be able to use the standard C++ > > API for reading in messages, since the data is already on the wire in > > byte format. > > > > - Adam > > -- > > You received this message because you are subscribed to the Google Groups > "Protocol Buffers" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]<protobuf%[email protected]> > . > For more options, visit this group at > http://groups.google.com/group/protobuf?hl=en. > > > -- You received this message because you are subscribed to the Google Groups "Protocol Buffers" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/protobuf?hl=en.
