Hi Denis,

I tried your suggested,  here is the code :https://github.com/wmz7year/ignite-test/commit/4eaa4231e165eaa4de00dab94cd394f629e68497
But I still got ClassNotFoundException.



I think. If I have lots of type servers. It will be ExampleServiceImpl1 2 3 4 5….,will look very bloated.

在 2015年11月10日,下午8:02,Denis Magda <dmagda@gridgain.com> 写道:

Jiang,

This exception happens exactly because you have two implementations with the same name. If the names were different you wouldn't get to the point of checksum validation.
Here I fully share Val's opinion that checksum's verification shouldn't be optional and it's a responsibility of an application to take care of such situations.

I see the following approaches you can use in your code to get required behavior:

1) As suggested below use the approach with Serializable + serialVersionUID. It will work;

2) More preferable is to have different implementations with different names (ExampleServiceImpl1, ExampleServiceImpl2, etc...). Is there any reasons you can't use this straightforward approach?
When the implementations are ready you can put their classes onto every machine in order to have them in the classpath or you can leverage IgniteConfiguration.peerClassLoadingEnabled feature.
The feature allows to load missing classes from a machine that sends compute based tasks onto a machine that will execute a task and you don't need to copy implementations' classes manually at all.
You can read more on this here: https://apacheignite.readme.io/docs/zero-deployment

Regards,
Denis

On 11/10/2015 10:39 AM, 姜 为 wrote:
Hi:


First start ModuleB, then start ModuleA.

ModuleB ExampleServiceImpl has three field.

    ModuleA ExampleServiceImpl has only one field.

Then throw Exception :

<邮件附件.png>
在 2015年11月10日,下午2:48,Denis Magda <dmagda@gridgain.com> 写道:

Hi,

+1 to Val.

Actually if you have different class names on different machines (DataEntity, ServiceEntity) I don't realize how you can get to the checksum validation stage.
In my understanding you should have caught ClassNotFoundException.

Provide me with a full runnable example, I'll run and see what you're trying to implement and at which point you fail.

--
Denis

On 11/10/2015 9:30 AM, Valentin Kulichenko wrote:
Hi,

I'm against optional checksum verification. It's not safe, adds one more
configuration property and I don't see any use case that can require this.

I also don't completely understand what you're trying to achieve. Can you
please describe the sequence of serialization/deserialization events that
you expect in your application?

-Val

On Mon, Nov 9, 2015 at 5:13 PM, 姜 为 <ydswcy513@gmail.com> wrote:

Hi:

        The implementations name maybe not same.

        Like my example:

        class DataEntity {
                Integer id;
                string name;
                Integer age;

                ….. and other

                Externalizable.read(in){
                        if(in.readBoolean()) {
                id = in.readInt();
            }
                        same as name,age...
                }

        Externalizable.write(out){
            out.writeBoolean(id != null);
            if(id != null) {
                out.writeInt(id);
            }
            same as name,age...
        }
        }

        class ServiceEntity {
                Integer id;
                Integer age;

                …. and other

                Externalizable.read(in){
                        if(in.readBoolean()) {
                id = in.readInt();
            }
            if(in.readBoolean()) {
                in.readString(); // ignore name
            }
            if(in.readBoolean()) {
                age = in.readInt();
            }
                        … and other
                }

        Externalizable.write(out){
            out.writeBoolean(id != null);
            if(id != null) {
                out.writeInt(id);
            }
            out.writeBoolean(false); // null for name
                       out.writeBoolean(age != null);
            if(age != null) {
                out.writeInt(age);
            }
                    … and other
        }
        }

        The other implementation class can be serialized and deserialized
custom rules by Externalizable.read and Externalizable.write.
        Each of the different types of servers property needs are
different,it does not require a complete serialization.




在 2015年11月9日,下午10:22,Denis Magda <dmagda@gridgain.com> 写道:

Hi,

As I understand both servers have different implementations but the
names of those implementations are the same, correct?
Because otherwise I don't see how your code could get to the point of
checksum validation if one implementation's name is ServiceEntity while the
other's is DataEntity.
If my assumptions above are correct then I would recommend to do the
following:
1) Extend Serializable instead of Externalizable

interface Entity extends Serializable {
    .....
}

2) Add custom serialVersionUID to each implementation. This will help
you get rid off checksum related exception
class EntityImpl implements Entity {
private static final long serialVersionUID = 0L;
......
}


Regards,
Denis

On 11/8/2015 3:27 PM, 姜 为 wrote:
Hi guys:

     I’m using ignite 1.4.
     In IgniteCompute.call will transfer of an object to the cluster.
    The object should implement Serializable or Externalizable
interface.
    OptimizedClassDescriptor.read method will check whether the object
is in the same class.
    In my use case,I have some type of servers in cluster.
    The server type A will check the business,and the server type B
will persistent data.
    There is a entity interface Entity extends Externalizable have
different implementations on different servers.
    Such like this:

    interface Entity extends Externalizable {
     method a();
     method b();
             method c();
     }

     class  ServiceEntity implements Entity {
     method a(){
             // do something...
     }

     method b(){
             // do something...
     }

     method c(){
             throw new UnsupportedException...
     }

     Externalizable.read...
     Externalizable.write...
    }

    class DataEntity implements Entity {
     method a(){
             // do something...
     }

     method b(){
             throw new UnsupportedException...
     }

     method c(){
             // do something...
     }

     Externalizable.read...
     Externalizable.write...
    }


    And IgniteCompute.call(new IgniteCallable(
             public Object call(){
                     Entity.a() or b and c;..
             }
     ));

   Different implementations of the same class are to achieve read and
write methods.
   But OptimizedClassDescriptor.read will check the class sum and throw
ClassNotFoundException.
   I recommend verifyChecksum object set as optional,and I really need
is change.
   Here is my pr:
   https://issues.apache.org/jira/browse/IGNITE-1854 <
https://issues.apache.org/jira/browse/IGNITE-1854> <
https://issues.apache.org/jira/browse/IGNITE-1854> <
https://issues.apache.org/jira/browse/IGNITE-1854>
      https://github.com/apache/ignite/pull/200/ <
https://github.com/apache/ignite/pull/200/> <
https://github.com/apache/ignite/pull/200/> <
https://github.com/apache/ignite/pull/200/>