buf.enc_ndr_long(0); /* momentarily skip alloc hint */
            buf.enc_ndr_short(0); /* context id */
            buf.enc_ndr_short(getOpnum());
        }

        encode_in(buf);
        this.length = buf.getIndex() - start;

        if (this.ptype == 0) {
            buf.setIndex(alloc_hint_index);
            this.alloc_hint = this.length - alloc_hint_index;

            buf.enc_ndr_long(0); /* momentarily skip alloc hint */
            buf.enc_ndr_short(0); /* context id */
            buf.enc_ndr_short(getOpnum());
        }

        encode_in(buf);
        length = buf.getIndex() - start;

        if (ptype == 0) {
            buf.setIndex(alloc_hint_index);
            alloc_hint = length - alloc_hint_index;
            buf.enc_ndr_long(alloc_hint);

 * encode/decode operation.
 */
public class DcerpcMessageTest {

    /**
     * A trivial concrete subclass used for testing. It simply writes a
     * single small value in {@code encode_in} and reads it in
     * {@code decode_out}.
     */
    private static class TestMessage extends DcerpcMessage {
        int decodedValue = 0;

        TestMessage() {
            /* nothing */
        }

        this.ptype = 11;
        this.flags = DCERPC_FIRST_FRAG | DCERPC_LAST_FRAG;
    }

    @Override
    public int getOpnum() {
        return 0;
    }

    @Override
    public void encode_in(final NdrBuffer buf) throws NdrException {
        buf.enc_ndr_short(this.max_xmit);
        buf.enc_ndr_short(this.max_recv);
        buf.enc_ndr_long(0); /* assoc. group */
        buf.enc_ndr_small(1); /* num context items */

        ptype = 11;
        flags = DCERPC_FIRST_FRAG | DCERPC_LAST_FRAG;
    }

    @Override
    public int getOpnum() {
        return 0;
    }

    @Override
    public void encode_in(final NdrBuffer buf) throws NdrException {
        buf.enc_ndr_short(max_xmit);
        buf.enc_ndr_short(max_recv);
        buf.enc_ndr_long(0); /* assoc. group */
        buf.enc_ndr_small(1); /* num context items */

     * @throws NdrException if decoding fails
     */
    protected abstract void decodeWitnessParameters(NdrBuffer buf) throws NdrException;

    @Override
    public void encode_in(NdrBuffer buf) throws NdrException {
        encodeWitnessParameters(buf);
    }

    @Override
    public void decode_out(NdrBuffer buf) throws NdrException {
        decodeWitnessParameters(buf);