-- binary
04 0f # version, type
00 70 # length
12 34 56 78 # xid
00 01 # command
03 # group_type
00 # pad
00 00 00 05 # group_id
00 30 # buckets[0].len
00 01 # buckets[0].weight
00 00 00 05 # buckets[0].watch_port
ff ff ff ff # buckets[0].watch_group
00 00 00 00 # pad
00 00 # buckets[0].actions[0].type
00 10 # buckets[0].actions[0].len
00 00 00 05 # buckets[0].actions[0].port
00 00 # buckets[0].actions[0].max_len
00 00 00 00 00 00 # pad
00 00 # buckets[0].actions[1].type
00 10 # buckets[0].actions[1].len
00 00 00 06 # buckets[0].actions[1].port
00 00 # buckets[0].actions[1].max_len
00 00 00 00 00 00 # pad
00 30 # buckets[1].len
00 01 # buckets[1].weight
00 00 00 06 # buckets[1].watch_port
ff ff ff ff # buckets[1].watch_group
00 00 00 00 # pad
00 00 # buckets[1].actions[0].type
00 10 # buckets[1].actions[0].len
00 00 00 05 # buckets[1].actions[0].port
00 00 # buckets[1].actions[0].max_len
00 00 00 00 00 00 # pad
00 00 # buckets[1].actions[1].type
00 10 # buckets[1].actions[1].len
00 00 00 06 # buckets[1].actions[1].port
00 00 # buckets[1].actions[1].max_len
00 00 00 00 00 00 # pad
-- python
ofp.message.group_modify(
    xid=0x12345678,
    group_type=ofp.OFPGT_FF,
    group_id=5,
    buckets=[
        ofp.bucket(
            weight=1,
            watch_port=5,
            watch_group=0xffffffff,
            actions=[
                ofp.action.output(port=5, max_len=0),
                ofp.action.output(port=6, max_len=0)]),
        ofp.bucket(
            weight=1,
            watch_port=6,
            watch_group=0xffffffff,
            actions=[
                ofp.action.output(port=5, max_len=0),
                ofp.action.output(port=6, max_len=0)])])
-- java
    OFActions actions = factory.actions();
    builder
      .setXid(0x12345678)
      .setGroupType(OFGroupType.FF)
      .setGroup(OFGroup.of(5))
      .setBuckets(ImmutableList.<OFBucket>of(
        factory.buildBucket()
          .setWeight(1)
          .setWatchPort(OFPort.of(5))
          .setWatchGroup(OFGroup.ANY)
          .setActions(ImmutableList.<OFAction>of(
            actions.output(OFPort.of(5), 0),
            actions.output(OFPort.of(6), 0)
          ))
          .build(),
        factory.buildBucket()
          .setWeight(1)
          .setWatchPort(OFPort.of(6))
          .setWatchGroup(OFGroup.ANY)
          .setActions(ImmutableList.<OFAction>of(
            actions.output(OFPort.of(5), 0),
            actions.output(OFPort.of(6), 0)
          ))
          .build()
         )
      )
      .build();