Content Addressable Storage (CAS) support

Document created by resplin Employee on Jun 6, 2015
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The official documentation is at: http://docs.alfresco.com



Community Contribution Ideas


Project Description


Goal of this project is to provide integration with CAS systems. CAS systems are storage systems based not on location address but on content address. When a CAS is asked to store a file it computes an hash based on its content, it returns it as the address of the stored content and proceed to physically store the content. This address (it's a hash, e.g. d8668fbab44d88f8601e625fd88dee84) is then used as the key to retrieve the content, so when the CAS is presented this address it returns the associated content. As hashing algorithms give a unique association between content and its hashing, this system guarantee:


  • Content integrity: if stored content has been altered then there's a mismatch between hash passed as address and hash computed on the fly
  • Redundancy avoidance: if CAS is asked to store a content already stored it recognizes that the hash is already present and so doesn't store it again.

Project Requirements/Objectives


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Initial Project Scope


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Discussion of Design/Implementation Approach


For what I understand, anyone feel free to correct me, it's a matter of making an implementation of another content store, ex. we can have a new package org.alfresco.repo.content.cas taking as template the filestore implementation made in org.alfresco.repo.content.filestore.


Comments


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XAM

I would propose a XAM integration which would allow to cover multiple CAS stores with one interface (incl. the EMC Centera).

UPDATE: I would see two phases for this integration: 1) storage of the content via XAM on the storage; 2) additional storage of the metadata of the object with the content (e.g. as XML) to fulfill OAIS requirements and have a possibility to recover the metadata when the leading system crashes (by reading and interpreting the data stored via XAM).

Anybody interested in an implementation please contact me (steffen . schilke (a) gmx . net) I would need some pointers where to fiddle to add these into Alfresco and some brush up on development with it.

S.W.Schilke




Comment from  fcorneli@prdbe.jnj.com tel 32-14-603327

We have already implemented a CAS store for Alfresco based on the CASTor product from
Caringo. We have donated the code to Alfresco.
Ask Paul (H-H) or Mike (Farman)

Frans Cornelissen




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Joe Bloggs



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