Re: paper on Prevayler

Karl mentioning schema evolution reminded me of this:
http://prevayler.org/old_wiki/ThereCanOnlyBeOne.html

I use plain serialization when I have compatible changes such as
adding a field (most of the time) and the above for incompatible
changes (such as changing the type of a field).

Klaus

On Mon, Aug 4, 2014 at 7:51 AM, Karl Wettin <[email protected]> wrote:
> Nice!
>
> How much are you planning to dive in to the details?
>
> There is a lot of text in the short-long-transaction-section that I more or
> less read as "A long transaction usually becomes long because of business
> logic being a part of the transaction". Perhaps it could simply say that.
> I've seen many newcomers to prevalence implementing systems this horrible
> way, and that includes myself.
>
> In the snapshot-speed-section you could consider mentioning hypothetical
> solutions to speed things up: native heap-dumps, decoupling classes at
> serialization and recoupling them at deserialization so they can be
> deserialized using multiple threads, etc.
>
> I also think there should be a bit about text about portability and domain
> class refactoring. What's possible to do with java.io.Serializable out of
> the box (adding new fields but not renaming, etc), that sometimes it's
> easier to dump data of previous system version in some independent format
> and import to the next version refactored version of the system, while
> others implement their own serialization strategy with domain class
> versioning and built in refactoring (I did that using java.io.Externalizable
> but it was quite a hassle and thus never did it again), etc.
>
>
> karl
>
> On 04 Aug 2014, at 04:40, Ralph Johnson <[email protected]> wrote:
>
> Klaus and I are writing a "pattern paper" about Prevayler.   An early draft
> is at
> https://drive.google.com/file/d/0Bx60GDHHyv4TMENlRTFsOGNDSk0/edit?usp=sharing
>
> I expect this paper to end up 10-12 pages long, which will be twice what it
> is now.  I'd love to get advice on what to add.
>
> Does anybody have references for example systems?
>
> At the moment, I am thinking that "small transactions" is not really a
> pattern, but a set a patterns.  The paper currently talks about measuring
> the length of transactions so you can find which ones are long.   I think
> that is a pattern.  It also talks about having a separate transaction for
> each employee in a payroll system instead of just having a "write checks"
> transaction.   That is another pattern.   I've thought of writing about
> continuations as a way of breaking up a big transaction into smaller ones.
> That would also be a pattern.   Can you think of patterns in how you break
> big transactions into small ones?
>
> I think you can leave comments in the document, or e-mail them to us.  Or
> post them here.
>
> -Ralph Johnson
>
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-- 
Valeu, Klaus.

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