Hi Martin! We haven't looked that close at protobuf yet (we don't use this for remoting purposes, only for persistence), and we needed something that was as simple as possible (i.e. departed from our regular "data expressed as case class"-approach as little as possible), and also was fully expressed at the class definition of our data classes (i.e. no extra definition files needed). It's probably mostly a mindset thing, I envision protobuf as a "protocol first"-kind of approach, but see this method as a more of a "code first"-approach. When the data to be made persistent is an instance of a case class, you also get the unapply implementation for your companion object for free, so you only need to provide the apply(Pair[Version, Product]) method to do the transformation from old to new. But I will definitely take closer look at protobuf and see what it offers (* reordering "read later"-list *).
Greetings Odd On Tue, May 20, 2014 at 6:05 AM, Martin Krasser <krass...@googlemail.com>wrote: > Hi Odd, > > why have you chosen this versioning approach instead of a protobuf based > one, for example? What are the advantages? > > > On 19.05.14 14:08, Odd Möller wrote: > > Hi! > > We have a versioning extension that we are experimenting with at the > moment (it is quite experimental at this point and completely without > tests): > https://github.com/odd/akka/tree/wip-persistence-odd/akka-contrib/src/main/scala/akka/contrib/persistence/versioning > > The basic idea is to attach a version to the actual data to be persisted > and then when saving the data, instead of serializing the data class as is, > save a tuple containing the data of the fields of the class. Then at load > time you can transform historic versions of the saved data to the latest > version (based on the attached version). > > For example: > > import akka.contrib.persistence.versioning._ > > // Version 1 -- present in the event log but no longer available at > runtime > // case class Name(first: String, last: String) extends Versioned[Name] > > // Version 2 -- current version of the class at runtime > case class Name(first: String, last: String, title: Option[String] = > None) extends Versioned[Name] > > object Name extends Versioned.Companion[Name] { > override def apply(data: (Version, Any)): Name = { > case (Version.Major(1), (first: String, last: String)) => Name(first, > last) > case (Version.Major(2), (first: String, last: String, title: > Option[String])) => Name(first, last, title) > case (v, d) => throw new IllegalStateException(s"Unknown version > encountered [version: $v, data: $d]") > } > } > > The versioned serializer needs to be present in the akka config: > > serializers { > versioned = "akka.contrib.persistence.versioning.VersionedSerializer" > } > serialization-bindings { > "akka.contrib.persistence.versioning.Versioned" = versioned > } > > > On Thu, May 15, 2014 at 7:41 PM, Per Johansson > <per.j.johans...@gmail.com>wrote: > >> What about using "versioned" objects (like Foo_v01, Foo_v02) and convert >> to the latest version when reading a snapshot? >> >> Anyone with experience of that approach? >> >> Was thinking it might be less work if you want to have e.g. maps after >> derserialization? (maps not supported in protobuf) >> >> /Per >> >> On Thursday, 8 May 2014 09:47:46 UTC+1, Martin Krasser wrote: >> >>> >>> On 08.05.14 10:43, Tim Pigden wrote: >>> >>> Hi >>> I've found a new thing to worry about :-) >>> If I use an eventsource model and content myself with the default >>> serialization and akka persistence, what's the likelihood of my serialized >>> objects becoming unreadable in the future? What's the long-term stability >>> of the default akka serialization mechanism? >>> >>> >>> By default, events are serialized with Akka's Java serializer. >>> >>> Is there a recommendation? >>> >>> >>> Use a >>> custom<http://doc.akka.io/docs/akka/2.3.2/scala/persistence.html#custom-serialization>protobuf >>> (or similar) serializer to serialize your events. This will >>> support backwards compatible changes to your event schema. >>> >>> Tim >>> -- >>> >>>>>>>>>> Read the docs: http://akka.io/docs/ >>> >>>>>>>>>> Check the FAQ: >>> http://doc.akka.io/docs/akka/current/additional/faq.html >>> >>>>>>>>>> Search the archives: >>> https://groups.google.com/group/akka-user >>> --- >>> You received this message because you are subscribed to the Google >>> Groups "Akka User List" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to akka-user+...@googlegroups.com. >>> To post to this group, send email to akka...@googlegroups.com. >>> >>> Visit this group at http://groups.google.com/group/akka-user. >>> For more options, visit https://groups.google.com/d/optout. >>> >>> >>> -- >>> Martin Krasser >>> >>> blog: http://krasserm.blogspot.com >>> code: http://github.com/krasserm >>> twitter: http://twitter.com/mrt1nz >>> >>> -- >> >>>>>>>>>> Read the docs: http://akka.io/docs/ >> >>>>>>>>>> Check the FAQ: >> http://doc.akka.io/docs/akka/current/additional/faq.html >> >>>>>>>>>> Search the archives: https://groups.google.com/group/akka-user >> --- >> You received this message because you are subscribed to the Google Groups >> "Akka User List" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to akka-user+unsubscr...@googlegroups.com. >> To post to this group, send email to akka-user@googlegroups.com. >> Visit this group at http://groups.google.com/group/akka-user. >> For more options, visit https://groups.google.com/d/optout. >> > > > -- > Martin Krasser > > blog: http://krasserm.blogspot.com > code: http://github.com/krasserm > twitter: http://twitter.com/mrt1nz > > -- > >>>>>>>>>> Read the docs: http://akka.io/docs/ > >>>>>>>>>> Check the FAQ: > http://doc.akka.io/docs/akka/current/additional/faq.html > >>>>>>>>>> Search the archives: https://groups.google.com/group/akka-user > --- > You received this message because you are subscribed to the Google Groups > "Akka User List" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to akka-user+unsubscr...@googlegroups.com. > To post to this group, send email to akka-user@googlegroups.com. > Visit this group at http://groups.google.com/group/akka-user. > For more options, visit https://groups.google.com/d/optout. > -- >>>>>>>>>> Read the docs: http://akka.io/docs/ >>>>>>>>>> Check the FAQ: >>>>>>>>>> http://doc.akka.io/docs/akka/current/additional/faq.html >>>>>>>>>> Search the archives: https://groups.google.com/group/akka-user --- You received this message because you are subscribed to the Google Groups "Akka User List" group. 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