12:09 p.m.
On 9 March 2017 at 10:22, Dan Berindei <dan.berindei(a)gmail.com> wrote:
On Thu, Mar 9, 2017 at 11:48 AM, Sanne Grinovero
<sanne(a)infinispan.org> wrote:
> Hi Dan!
>
Hey Sanne :)
> On 9 March 2017 at 09:38, Dan Berindei <dan.berindei(a)gmail.com> wrote:
>> Every store can have its own Key2StringMapper, so I really don't think
>> service discovery is appropriate here.
>
> I suggested a default, while maintaining the property as an override option.
>
> It won't make any difference to people in the situation you describe,
> but it will avoid trouble for many more users.
>
> In my experience when one develops a custom type & a custom
> Key2StringMapper, you really wouldn't have interest in creating
> multiple implementations for the same type. The only case in which I
> can see some use for allowing multiple conflicting registrations to
> the same type is for upgrade / migration cases..
>
The problem I see is that each store can only have one
Key2StringMapper implementation, so you're going to have conflicts
even if your caches use completely different key types. The store
doesn't know which key types the application actually uses, so it
can't pick the appropriate implementation when there are multiple ones
on the classpath.
Good point. I was hoping to allow different services to "contribute"
their different converters but I realise now that it would introduce a
risk of ambiguous representations.
They would need some standard scoping to know to which one to delegate
to on read operations. I wonder if we could enforce / validate that?
>> My favourite solution would be to have a default
Key2StringMapper
>> implementation that uses Java serialization (not our internal
>> marshalling, because that can change between versions). It could even
>> do base64 encoding for databases that don't have a VARBINARY/BYTEA
>> equivalent.
>>
Do you see any problem with using serialization everywhere?
I guess we could discuss alternative strategies, but it's an
orthogonal discussion right? You're proposing a different CacheStore
implementation, but people would still need a better way to associate
the adaptors to the types.
But to answer your question: yes I wouldn't like using Java
serialization: people need to be able to evolve their domain model.
When we had to "break" the string format in the Lucene mappers (as I
added a new field) we managed to do it in an evolutionary way: it
wasn't too hard to make sure we could read the old string format,
while with Java serialization this would have been a mess.
Also it would be nice to keep the representation as short as possible
for both efficient processing and storage space efficiency: Java
Serialization isn't particularly compact.
Thanks,
Sanne
Dan
>> Cheers
>> Dan
>>
>>
>> On Wed, Mar 8, 2017 at 6:34 PM, Sanne Grinovero <sanne(a)infinispan.org>
wrote:
>>> It seems I keep forgetting that the "key2StringMapperClass" needs
to
>>> be explicitly set when using the String based JDBC CacheStore, which I
>>> think is a quite popular store.
>>>
>>>
http://infinispan.org/docs/dev/user_guide/user_guide.html#storing_the_ind...
>>>
>>> I think we could remove the need to configure this with an appropriate
>>> service discovery?
>>>
>>> We could keep the property so to be able to override the discovery process.
>>>
>>> Would anyone volunteer to implement this?
>>>
>>> Thanks,
>>> Sanne
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