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https://issues.apache.org/jira/browse/JCR-3534?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13649962#comment-13649962
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Alexander Klimetschek commented on JCR-3534:
--------------------------------------------
@Tommaso: There are 2 things:
a) api or not for creating the binary: since the requirement here is an
application level protocol, there must be an API, otherwise it could not know
if it should resend the full binary or not. The application level protocol
currently cannot and should not know if the datastores are shared or not.
AFAICS, the discussion so far did not result in avoiding an API, just to make
sure it's a _secure_ API.
In my above comments I missed the proposed trick to use
"createValue(java.lang.String value, PropertyType.BINARY)" - but I don't see
that in the patch either. This would look something like this IIUC, instead of
the getBinaryFromSecureID() in my above snippet:
Node node = ... // current node written
Binary binary;
if (messageData.hasBinaryStream()) {
binary = getBinaryFromStream(messageData, session);
} else {
String message = messageData.getBinaryMessage(); // get from custom
protocol
try {
binary = session.getValueFactory().createValue(message,
PropertyType.BINARY);
} catch (ValueFormatException e) {
// not supported / wrong secret / referenced binary not found
return ASK_FOR_BINARY_STREAM;
}
}
node.setProperty("jcr:data", binary);
It is important however that createValue() will only return a binary if the
message is right; if it creates a binary of the string contents (not sure if
that is currently the case if you call createValue() this way, then this trick
cannot work and we do need another API.
b) reading the binary: could you show me the application code reading such a
binary just using the JCR API how it gets the actual data? This is completely
missing yet (the test in the patch uses DataStore.getRecord(), but that is
Jackrabbit internal).
> 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.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
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