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From Norman Maurer <nor...@apache.org>
Subject Re: What's in a store?
Date Mon, 20 Sep 2010 12:50:30 GMT
Hi Eric,

comments inside.

2010/9/20 Eric Charles <eric@apache.org>:
>  Hi,
> It's always possible to inject the mailboxmanager in mailets
> (ToRepository),... but we would  really gain to unify/simplify the 2.3 mail
> storage with the 3.0 one.
> In 2.3, we have such class hierarchy:
> Repository
> +- AbstractFileRepository
>    +- File_Persistent_Object_Repository
>    +- File_Persistent_Stream_Repository
> MailRepository
> +- AbstractMailRepository
>    +- FileMailRepository
>    +- JCRMailRepository
>    +- JDBCMailRepository
> +- MBoxMailRepository
> +- SpoolRepository
>    +- InMemorySpoolRepository
>    +- MailStoreSpoolRepository
> Store
> +- AbstractMailStore
>    +- SpringMailStore
> In short, the SpringMailStore is responsible to register the
> MailRepositories and to select them.

Thats correct but I would more call it a hack to let it Spring load it
 ;) The whole Store interface is just a left-over from the old days
were we used Avalon/Excalibur for DI and component loading. I would be
more in favor to replace the Store interface with something which is
not such a mess..

> In Mailbox projects introduced for 3.0, we have:
> MailboxManager
> +- StoreMailboxManager
>    +- InMemoryMailboxManager
>    +- JCRMailboxManager
>    +- JPAMailboxManager
>    +- MaildirMailboxManager
> With new 3.0 implementation, we only can deliver in one-and-only-one store
> (jpa, jcr,...).
> We should overcome this limitation.

Thats the question.. Do we really want to overcome this ? I'm not sure
if the MailboxManager should replace the MailRepository for such cases
as storing mails in
the error processor etc. With the MailRepository we are able to store
the whole Mail including Mail Attributes etc, thats not the case with
MailboxManager. MailboxManager was not designed for that purpose. Its
just a storage for Mailboxes nothing more, nothing less ;) IMHO it
would make sense to "not merge" this twos and so only allow to
configure one MailboxManager implementation..

> Way to go further...:
> We should also discuss on the future way to evolve. There are different
> options/steps to go further with that unification/simplification:
> A/ Should we consider the MaiboxManager as just another MailStore, so
> developing a MailboxManagerMailStoreAdapter class and add the needed entries
> to the mailstore.xml, so the existing SpringMailStore mecanic is invoked.
> B/ Or simplifying and removing the Store and MailRepository hierarchy.
> C/ Any other options... ?
See above..

> This could be also thought in parallel with a discussion on UsersRepository
> hierarchy, so we have coherent way of working within James.
> I we go for option B/, it would be logical to also simplify the
> UsersRepository hierarchy.
> (Think also the DomainList has no Repository notion).

I think its a bit different. We should just Remove the UsersStore and
VirtualUserTableStore. There is no need to support more the one
implementation at one time
here. This just makes things more complex.

> I think we should also extract the 2.3 classes/interfaces, and place them in
> the correct mailbox projects (also create new mailbox projects for example
> apache-james-mailbox-file that will contain FileMailRepository,..).


> Eric
> On 6/09/2010 08:24, Eric Charles wrote:
>>  OK, we've done a picture of the current situation.
>> I would like to pick an simple example as strong requirement to unify the
>> store/repository (whatever then name is) API across all projects.
>> In spoolmanager.xml, we define respositoryPath such as db://maildb/spam.
>> These repositoryPath are used in mailets,...
>> Let's say I want to develop a mailet that under certain conditions stores
>> the mail in a folder (let's say "spam" folder) of the user.
>> If the mailbox is for example JCR, I have no standard way to define the
>> folder path in the james-server "repository" syntax. Or I must invent one...
>> (jcr://...? or a more generic one mailbox:///? because I don't want to
>> change spoolmanager.xml if spring-beans.xml changes)
>> If both are linked, we have clear conventions to implement.
>> And we can always release any project when we want.
>> This is why I think we should link in a way or another the james-server
>> repository and the imap store. Not only on syntax extension, but also on
>> implementing classes.
>> Tks,
>> Eric
>> On 6/09/2010 07:49, Norman Maurer wrote:
>>> Comments inline..
>>> 2010/9/6 Eric Charles<eric@apache.org>:
>>>>  Hi Norman,
>>>> pop3server has store in its pom, but does not really need it. I will
>>>> carefully test before commit the changes.
>>> Should be safe to remove it then..
>>>> JPAUser is accessed in JPAUsersRepository (instanciated via the
>>>> LocalUsers
>>>> repository) while JPAMailbox is managed in JPAMailboMapper is accessed
>>>> via
>>>> JPAMailboxMapper. JPAUsersRepository and JPAMailboxMapper are created in
>>>> completely different ways.
>>> Ok, I think the "mapper stuff" is just in imap to make implementing
>>> different Mailbox stores easy. So its ok to have it work different.
>>>> I see that james-server has a whole infrastructure around "repository".
>>>> Imap
>>>> has not that infrastructure and rely on implementing different stores in
>>>> different projects. The questions are:
>>>> 1.- must imap go to server repository infra?
>>> Not sure..
>>>> 2.- must server repository infra be simplified and merged with the imap
>>>> approach?
>>> -1 No
>>>> 3.- must we leave that separated?
>>> Have them seperate allow to have a independend release cycle. Well I
>>> know imap had no release yet but I hope to get it done this week.
>>>> btw, even in james-server, all persistence does not go the same way:
>>>> domainlist does not work completely with repository.
>>>> If you take the JDBCDomainList, it needs a repositoryPath which is
>>>> db://maildb/domain (I don't see directly the relation with the
>>>> persistence.xml for the mailbox, and however, it stores in the same
>>>> database...). However, if you take the JPADomainList, it does not need
>>>> any
>>>> "repository", because it's using the persistence.xml.
>>>> I mean, the repository principle has some exceptions in james-server.
>>> The RepositoryPath stuff is from the good old days. With this concept
>>> its possible to use more then one db. Like db://maildb/domain (db =
>>> maildb, table = domain) and db://maildb2/domain (db= maildb2, table =
>>> domain). The whole concept is a "left-over" from using excalibur and
>>> avalon. To be honest I don't care if we remove it at all, one db
>>> should be enough...
>>>> Tks,
>>>> Eric
>>>> On 5/09/2010 20:11, Norman Maurer wrote:
>>>>> Hi Eric,
>>>>> comments inside..
>>>>> 2010/9/5 Eric Charles<eric@apache.org>:
>>>>>>  Hi All,
>>>>>> The store project has the mappers and imports some classes of mailbox
>>>>>> (mailboxmanager,...), so 'store depends on mailbox'.
>>>>>> To access some mailbox/subscription, you need to use the maibox
>>>>>> project
>>>>>> (example: imap-processor depends on mailbox, and imapProcessor bean
>>>>>> injected with mailboxmanager/subscriptionManager). So far, so good.
>>>>>> mailbox is the interface to the mailboxes,...": I had a quick look
>>>>>> the
>>>>>> pop3server dependencies and saw that it was depending on store. I
>>>>>> didn't
>>>>>> find that logical, removed it, and it was still compiling. Logical...
>>>>>> Thinking in "what depends on what" helps much.
>>>>> pop3server should not depend on store and only depend on mailbox. If
>>>>> its not the case its a bug..
>>>>>> However, the other '"domain classes" (user, virutalusertable, domain
>>>>>> in
>>>>>> the
>>>>>> sense 'domain.tld') are accessed in a all different way. This comes
>>>>>> probably
>>>>>> from the history (before using imap projects, server used its own
>>>>>> storage
>>>>>> system which has been kept). In spring-beans.xml, you've got:
>>>>>> - users-store: org.apache.james.container.spring.SpringUsersStore
>>>>>> class
>>>>>> being injected via @Resource
>>>>>> - virtualusertable-store :
>>>>>> org.apache.james.container.spring.SpringVirtualUserTableStore being
>>>>>> injected
>>>>>> via @Resource
>>>>>> - domainlist: XML/JDBC/JPADomainList being injected via @Resource
>>>>>> I see there 3 differents access to the persisted domain classes
>>>>>> (Mailbox,
>>>>>> Message, Subscription, Domain, User, VirtualUserTable):
>>>>>>  1. Injection of mailbox project (MailboxManager, MessageManager,
>>>>>>     SubscriptionManger,...) beans
>>>>>>  2. Injection of spring-common project (SpringUsersStore,
>>>>>>     SpringVirtualUserTableStore) beans
>>>>>>  3. Injection of core-function project (XML/JDBC/JPADomainList)
>>>>>> If you persist everything in a database, accesses for JPAUser is
>>>>>> completely differently compared to the JPAMailbox for example.
>>>>> Could you explain whats the dfference ?
>>>>>> Coming to the point, should we:
>>>>>>  1. Continue to live with heterogeneous access the persistence layer?
>>>>>>  2.   Have uniform access to persistence for all services and all
>>>>>>     domains? In this case, a store project would be a good name,
>>>>>>  is
>>>>>> already taken... we could always rename the existing one...
>>>>>> WDYT?
>>>>>> Eric
>>>>>> PS: I didn't even talked of the AbstractFileRepository
>>>>> The whole *Store stuff is just a pita (james-server).. The idea with
>>>>> its was that you can configure for example different UserRepositories
>>>>> and just lookup the right one via the UsersStore. So its really
>>>>> flexible. However the loading of the classes + injecting the right
>>>>> dependencies is really complicated with this. I'm open to new ideas to
>>>>> make it more easy :)
>>>>> ---------------------------------------------------------------------
>>> Bye,
>>> Norman
>>> ---------------------------------------------------------------------


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