Implementing zLib compression in Flex and Java

Question

Hi
I am sending some JSON data from my Flex application to the Java side for business processing. Now on top of that, I have added some code to compress(zLib) the data at Flex side and then pass it through Request and uncompress the same at java side. But at the java layer, the uncompressed data is still not in readable/usable format.

Putting the code in here for reference.

// Flex Code for encoding

var bytes:ByteArray = new ByteArray();
bytes.writeObject(JSON.encode(someObj));
bytes.position = 0;
bytes.compress();
variables.encodeJSONStr = bytes;
requester.data = variables;
loader.load(requester);


//JavaCode for decoding

String json = req.getParameter("encodeJSONStr");
byte[] input = json.getBytes();
Inflater decompresser = new Inflater();
decompresser.setInput(input);
byte[] result = new byte[1000];
int resultLength=0;
resultLength = decompresser.inflate(result);
decompresser.end();
String outputString = new String(result, 0, resultLength, "UTF-8");
System.out.println("\n\n resultLength>>>"+resultLength); // O/P comes as Zero

Can someone point put the issue in here or some better approach for compression of data when sending from Flex to Java.

TIA
-P

Answer 1

First you should try if Flex does the zLib compression properly (by uncompressing the data sent with another tool).

On the Java side you can try to use the InflaterInputStream which is easier to handle than the more low level Inflater. I had some issues with the Java native implementation and ended up using the jZlib which offers a zlib compression uncompression in pure Java.

Answer 2

Some time ago I wrote a short post about sending compressed data between flex/java, maybe it helps: http://cornelcreanga.com/2008/07/actionscript-compressing-strings/