jackrabbit-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Jukka Zitting (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (JCR-3534) Efficient copying of binaries across repositories with the same data store
Date Fri, 10 May 2013 14:55:17 GMT

    [ https://issues.apache.org/jira/browse/JCR-3534?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13654527#comment-13654527

Jukka Zitting commented on JCR-3534:

Note that an explicitly configured or generated "secret" is not necessary in all cases, as
all we need is some non-public and un-guessable key that is different for each distinct backend
store. For example the database and S3 data stores could combine the connection parameters,
including the secret password or access key, to generate such a reference key without the
need for extra configuration or key storage.

So we have at least three ways in which a data store could get such a reference key:

1. As an explicit "secret" (perhaps "referenceKey" was a better name) configuration parameter
2. As a random string that's automatically generated at first startup and stored along with
the rest of the data store contents
3. As a combination of existing configuration parameters

An implementation could even use a combination of the above. I don't have much preference
on any specific implementation, as they all cover the same basic functionality (each with
its own minor benefits and downsides compared to the others) and there's no inherent difference
security as anyone with access to the <DataStore/> configuration entry will any case
have full access to the entire data store.

In any case I agree with Angela that whatever we do, the default repository.xml file should
*not* contain a pre-defined reference key, as that'll make all default deployments share the
same key even if their data stores are distinct.

Also, another change that occurs to me is that the getIdentifierFromReference() method should
also verify the existence of the referenced record before returning the identifier, as otherwise
we could end up with dangling references to garbage-collected binaries.
> Efficient copying of binaries across repositories with the same data store
> --------------------------------------------------------------------------
>                 Key: JCR-3534
>                 URL: https://issues.apache.org/jira/browse/JCR-3534
>             Project: Jackrabbit Content Repository
>          Issue Type: New Feature
>          Components: jackrabbit-api, jackrabbit-core
>    Affects Versions: 2.6
>            Reporter: Felix Meschberger
>            Assignee: Tommaso Teofili
>         Attachments: JCR-3534.2.patch, JCR-3534.3.patch, JCR-3534.4.patch, JCR-3534.patch,
> we have a couple of use cases, where we would like to leverage the global data store
to prevent sending around and copying around large binary data unnecessarily: We have two
separate Jackrabbit instances configured to use the same DataStore (for the sake of this discussion
assume we have the problems of concurrent access and garbage collection under control). When
sending content from one instance to the other instance we don't want to send potentially
large binary data (e.g. video files) if not needed.
> The idea is for the sender to just send the content identity from JackrabbitValue.getContentIdentity().
The receiver would then check whether the such content already exists and would reuse if so:
> String ci = contentIdentity_from_sender;
> try {
>     Value v = session.getValueByContentIdentity(ci);
>     Property p = targetNode.setProperty(propName, v);
> } catch (ItemNotFoundException ie) {
>     // unknown or invalid content Identity
> } catch (RepositoryException re) {
>     // some other exception
> }
> Thus the proposed JackrabbitSession.getValueByContentIdentity(String) method would allow
for round tripping the JackrabbitValue.getContentIdentity() preventing superfluous binary
data copying and moving. 
> See also the dev@ thread http://jackrabbit.markmail.org/thread/gedk5jsrp6offkhi

This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators
For more information on JIRA, see: http://www.atlassian.com/software/jira

View raw message