Mailing-List: contact dev-help@jackrabbit.apache.org; run by ezmlm
Precedence: bulk
Reply-To: dev@jackrabbit.apache.org
Date: Thu, 21 Mar 2013 14:33:17 +0000 (UTC)
From: "Jukka Zitting (JIRA)" <jira@apache.org>
To: dev@jackrabbit.apache.org
Message-ID: <JIRA.12637199.1363355457852.26989.1363876397175@arcas>
In-Reply-To: <JIRA.12637199.1363355457852@arcas>
References: <JIRA.12637199.1363355457852@arcas>
Subject: [jira] [Commented] (JCR-3534) Add
 JackrabbitSession.getValueByContentId method
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit


    [ https://issues.apache.org/jira/browse/JCR-3534?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13608985#comment-13608985 ] 

Jukka Zitting commented on JCR-3534:
------------------------------------

Note that there is no guarantee that the userIds of the two repositories have no relation with each other, so I don't think it should be included in a mechanism like the one proposed.

Instead, a HMAC of the content identifier, signed by the underlying data store should be good enough. The target repository can check that the message comes from the same underlying data store, so anyone who has access to such a code already has access to the related binary through one of the repositories attached to that data store. Thus allowing the user to access the binary doesn't reveal anything he or she couldn't already access by other means.

Ideally I'd see such a HMAC to be passed transparently as a part of Binary instances acquired from a remote RMI or Davex connection to the source repository. The target repository would automatically extract and evaluate the information based on the type of the passed Binary instance, and could always fall back to streaming the data if for example the HMAC doesn't match. The client would use the pattern I outlined above, the only difference being that repositoryA would be a remote RMI or Davex connection instead of a local cluster node.
                
> Add JackrabbitSession.getValueByContentId method
> ------------------------------------------------
>
>                 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
>         Attachments: 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