DBlobCache

     Scale the file storage for your rails application.
    No more rsync betwen SCGI/FCGI servers to replicate data.
    Use ActiveRecord to store all your data, incuded blobs. Avoid DB bottlenecks!
    Store all data in your database in order to make backup easy
    Data is replicated and stored on-demand
    Can be used with Apache,lighttpd or XCGI (CGI,FCGI,SCGI,Mongrel)
    High cache hit rate!

What?

Yes, you hear well, store files in database.

DBBlobCache Is a DRb (Distributed Ruby) server that cache database blobs in filesystem, aiming to lighttpd/Apache quickly serve static files. 

Instead of generate ActiveRecord dinamic content at high cost database performance, DBBlobCache only retrieve data from database the first time is used and when it's updated.
How it works.

Desing

https://sites.google.com/site/juanpedroparedes/dbblobcache
https://sites.google.com/site/juanpedroparedes/drbcachedbstore.png
 

    First lighttpd got a request like /store/list
    It forward the request to XCGI servers cause generates a 404 and dispatch.fcgi takes care of it
    XCGI receives the request as controller store, list method
    ActiveRecord fetch data and use helper(DRB method) to create image URL's
    Helper retrieve file if not stored yet or was updated
    Helper store the file into a directory to be serve later by web server
    XCGI return HTML page
    Next requests, will be to fetch static files from directory used.
    As expected, there are initial cache miss, and later a high percentage of cache hits.

How to install.

    SVN 

#svn co svn://iquis.com/dbblobcache/trunk/ dbblobcache

To make svn external to our rails app

#cd /path_to_rails_root/ 

#svn propedit vendor/plugins

add:

dbblobcache svn://iquis.com/dbblobcache/trunk/ 

    Read examples/databse.yml and add entry to  RAILS_ROOT/config/database.yml, this is the configuration file. 

#database.yml entry
dbblobcache:
  root: public
  directory: files
  table: items
  blob: image
  adapter: mysql
  database: example_database
  username: username
  password: password
  host: database_host
  port: 3306

    Read  examples/example_controller and modify your controller adding a initialize method like this:

#The controller must to start client binding to drb server (now localhost)
  def initialize
    DRb.start_service
    @dbblobcache = DRbObject.new(nil, "druby://:8880")
    #@dbblobcache = DRbObject.new(nil, "druby://lithty:8880")
  end

    Read examples/example_list.rhtml and see how to use @dbblobcache like a image helper

 tag("img", :src=> @dbblobcache.get_image(item.id,"",item.extension,item.date), :border=>0)

    Read examples/example.sql and examples/example_model.rb to see how to store date and blob stuff
    Start in you rails root 

#./vendor/plugins/dbblobcache/dbblobcache

    Try your application

Questions and little answers

    Are you crazy? store files in database!

Files are for filesystem and data is for database, i get the better of two.

    How stable is the code?

Is completely alpha code, please try it, and help to inprove it. 

    Can I put DBBlobCache in XCGI servers as a rails plugin? 

In future the answer maybe yes, like file_column but taking care of database

    Why not to improve file_column?

Is a great idea, but at the time, is a must to check and bench this approach.

     Why not make a plugin?

Well first i must read plugin doc :P
	 

Contact: GTalk GMail at juanpedro.paredes AT gmail.com