Document management system: what to use as document storage backend?

Question

I want to make a document management system.
What do profesional sollutions (Alfresco, Liferay social office, others) use for storing and versioning documents?
What else can I use?

Key points:

• storage space optimization (deltas, compression ...)
• versioning
• ability to index docs (can be external)

Answer 1

alfresco is commonly used as the backend, it has a nice REST API. You can also define your own integration API if you don't like the included one.

Answer 2

Most of the enterprise document management solutions I've seen (Cimage, Documentum, LiveLink) definitely don't care about #1. Storage is relatively cheap, especially if it's storage vs processing (store and retreieve). They mostly rely on filesystem based storage - perhaps with name abstraction such that ShoppingList.doc perhaps becomes 20100909100101a.doc.rev1, with a database tracking the given-name, the stored name, revisions, and various other data {MIME type, headers & properties etc}. By not generating deltas + compression you get indexing very easily from any number of existing products/agorithms. Versioning is also extremely simple with this approach.

Depending on the size and scale you're building, you could also store versioned files within a database.

An (S)FTP or CIFS storage process would also allow your software to run on an app server with modest space, but store the files+history on a file or cloud server of some sort - although this isn't much different from filesystem based storage.