Re: [jgroups-users] v3->v4 move, problem with castMessage

On 02/11/17 17:44, Questions/problems related to using JGroups wrote:
> 
>         Am having various problems with our v3->v4 change. Trying to
>         focus on them one at a time, I wanted to ask about the
>         castMessage change. We were doing this before to send a message
>         out to every node, collect responses, etc:
> 
>                   RspList<MyOb> rspList = md.castMessage(null,
>                       new Message(null, myString), ro);
> 
>         ...where myString is actually a constant starting with "n" and
>         MyOb is a Serializable object with some primitive data in it and
>         one Address object (*).
> 
> 
>     I don't see a myObj instance getting passed to the call?
> 
> 
> Where would that go? I don't see it in the v3 or v4 APIs. With jgroups 
> v3, we've been using that for years now and it always returns what I'd 
> expect. When I iterate over "for (Rsp<MyOb> rsp : rspList.values())" 
> rsp.getValue() always returns a MyOb.
> 
> I changed the castMessage contents to use Util.objectToByteBuffer 
> instead of string (our handle() method could get a couple different 
> things instead of strings), used the proper byte array length, and that 
> all works fine. Thanks for the information. So far each rsp.value is a 
> MyOb, so it's working.
> 
> Which leads me to the last question (for this thread anyway):
> 
> 
>         (*) Related: am getting a lot of FindBugs warnings now because
>         we have a couple Serializable objects we pass around that
>         include Address objects, and that isn't marked Externalizable
>         any more. Any advice there would also be appreciated.
> 
> 
>     I removed Serializable / Externalizable from Address, so they cannot
>     be serialized with Java serialization (which is a bad idea anyway!).
>     Use Util.writeAddress()/readAddress() instead
> 
> 
> Am not following yet. In the MyOj case above, the object used to be 
> something like (simplified):
> 
> public class MyOb implements Serializable {
>      private static final long serialVersionUID = // stuff
>      private final String this;
>      private final String that;
>      private final boolean a;
>      private final boolean b;
>      private final Address addr;
> 
>      // code
> }
> 
> Now I've marked 'addr' transient and set it when I iterate over the 
> RspList. That's working ok I think. But we have other cases, like the 
> object used to store shared cluster state, that's more like this:
> 
> public class MyOb2 implements Serializable {
>      private static final long serialVersionUID = // stuff
>      private String[] something;
>      private Address[] addresses1;
>      private Address[] addresses2;
> 
>      // code
> }
> 
> In v3.X that could all be sent over the wire because everything was 
> Serializable. Is there a suggested way to handle this in v4.X to reuse 
> jgroups util code as much as possible?

Yes, make it implement Streamable instead of Serializable


> Thanks,
> Bobby
> 
> 
> 
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-- 
Bela Ban | http://www.jgroups.org


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