public int doWrite(ByteChunk chunk,
    Response res) throws IOException 
{
            if (!response.isCommitted()) {
                // Validate and write response headers
                try {
                    prepareResponse();
                } catch (IOException e) {
                    // Set error flag
                    error = true;
                }
            }
            int len = chunk.getLength();
            // 4 - hardcoded, byte[] marshalling overhead
            int chunkSize = Constants.MAX_SEND_SIZE;
            int off = 0;
            while (len  > 0) {
                int thisTime = len;
                if (thisTime  > chunkSize) {
                    thisTime = chunkSize;
                }
                len -= thisTime;
                responseHeaderMessage.reset();
                responseHeaderMessage.appendByte(Constants.JK_AJP13_SEND_BODY_CHUNK);
                responseHeaderMessage.appendBytes(chunk.getBytes(), chunk.getOffset() + off, thisTime);
                responseHeaderMessage.end();
                output.write(responseHeaderMessage.getBuffer(), 0, responseHeaderMessage.getLen());
                off += thisTime;
            }
            return chunk.getLength();
}

Write chunk.