Tech talk live alfresco cmis

Alfresco
Florian Müller, Software Architect

Agenda

•  Prepared topics
o  Alfresco CMIS mapping

o  CMIS in Alfresco 3.X versus Alfresco 4.X

o  CMIS web scripts

o  Performance tuning

o  CMIS Browser Binding: CMIS via JSON

•  Your topics
o  Share experiences and ask questions

o  What is missing in the CMIS specification?

o  Which features should be added to the Alfresco OpenCMIS Extension?

Alfresco CMIS mapping 1/4

•  Documents
o  All types derived from cm:content
o  CMIS type id: “D:<alfresco type>”
o  CMIS query name: “<alfresco type>”
o  Exception: “cm:content”  “cmis:document”

•  Folders
o  All types derived from cm:folder
o  CMIS type id: “F:<alfresco type>”
o  Exception: “cm:folder”  “cmis:folder”


•  Relationships
o  All peer-to-peer relationships
o  CMIS type id: “R:<association type>”
o  CMIS query name is irrelevant because relationships are not queryable
o  CMIS base type “cmis:relationship” has no Alfresco equivalent

o  Only relationships with CMIS source and target objects are exposed!


•  Policies
o  All aspect types
o  CMIS type id: “P:<alfresco type>”
o  CMIS base type “cmis:policy” has no Alfresco equivalent

•  Any type outside the cm:content and cm:folder
hierarchy is not exposed via the CMIS interface!

•  http://wiki.alfresco.com/wiki/CMIS_Model_Mapping

CMIS in Alfresco 4.X 1/4

•  New CMIS implementation based on the
Apache Chemistry OpenCMIS server framework

•  Why has it been re-implemented?

o  OpenCMIS is used by several CMIS repositories.
Alfresco automatically benefits from all bug fixes and improvements.
o  One code base for the AtomPub and the Web Services binding
(and the Browser Binding).
o  Better CMIS specification compliance.
o  Better performance, less memory consumption,
handling of big documents.


•  How does this affect CMIS clients?

o  New URLs…
The old implementation and URLs will be available but are deprecated.

o  Specification compliant, generic CMIS clients shouldn’t see a difference.

o  Aspects and the Alfresco OpenCMIS Extension work as before.

o  If the CMIS Client make any assumptions about the format the object id,
it has to change! (See next slides.)


•  Alfresco 3.X Object Ids:

o  Current version document id: node ref
workspace://SpacesStore/e5787fce-7583-4b74-8836-8dcc94df4493

o  Version document id: current version node ref + “;” + version label
workspace://SpacesStore/e5787fce-7583-4b74-8836-8dcc94df4493;1.0

o  The creation of a new version doesn’t change the current version
document id.  Not spec compliant!

o  A client must not assume that a document id always represents the
current version!


•  Alfresco 4.X Object Ids:

o  Current version document id: node ref + “;” + version label

o  Version document id: current version node ref + “;” + version label

o  The creation of a new version changes the current version document id.
 Spec compliant!

o  General advise: Treat the object id as an opaque string.

CMIS Web Scripts 1/3

•  Alfresco 4.X has the OpenCMIS client embedded
and available in web scripts

•  Use case examples:

o  Alfresco Share mashups and federated queries

o  Synchronize documents between repositories

o  Publishing scenarios

o  Simple migration scenarios

CMIS Web Scripts 2/3

•  New JavaScript top level object: cmis
o  This object manages connections to CMIS servers.

o  Three connection types:
•  Current Alfresco server (uses OpenCMIS local binding if possible)
•  Preconfigured connection
•  Web script configured connection

var cmisConnection = cmis.getConnection(myConnectionId);
var cmisSession = cmisConnection.getSession();

model.folder = cmisSession.getRootFolder();
model.children = model.folder.getChildren().iterator();

Performance Tuning 1/4

•  CMIS = XML over HTTP over a network

o  Whenever you can avoid a call to the CMIS server, avoid it!

o  Sensible caching is important.

o  OpenCMIS and DotCMIS have first-level caching build in.
Make use of it and add your application specific caching.

o  OpenCMIS and DotCMIS  Operation Context


•  Be careful what you ask for…

o  Only ask for the properties you need!
Some properties are more expensive than others.

o  Never do perform “SELECT * FROM …” queries in production code.

o  Fetch allowable actions, ACLs, relationships and renditions only
if you need them!

o  Select sensible page sizes and depths! Only request the objects you need.
If you need all, choose a large page size.

o  OpenCMIS and DotCMIS  Operation Context


•  HTTP Keep-Alive

o  Many high-level requests consists of a burst of CMIS requests.

o  Reusing the same connection makes a difference!

o  Make sure HTTP Keep-Alive is turned on.

o  Always read content streams to the end and close them!


•  Compression

o  The CMIS XML compresses very well.

o  Compressed CMIS response are usually between 85% and 5% of the
original size.

o  Whenever network bandwidth is a bottleneck, turn compression on.

o  http://wiki.alfresco.com/wiki/CMIS#Compression

o  OpenCMIS and DotCMIS  Session Parameters

CMIS Browser Binding: CMIS via JSON

•  CMIS 1.1 will introduce a third binding:
The Browser Binding.

•  Optimized for CMIS application in web browsers.

o  Data transport format is JSON.

o  Works JavaScript and without a server-side client component.

o  Security and authentication designed for web browsers.

•  More efficient than the Web Services and the
AtomPub binding.

CMIS Browser Binding: CMIS via JSON

•  Apache Chemistry OpenCMIS will provide an
implementation for CMIS 1.0
o  Prototype is available.

o  It will be shipped with Alfresco 4.X but deactivated by default.

o  Online demo: http://cmis.alfresco.com/

Tech talk live alfresco cmis

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