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Wednesday, July 24, 2013

Using RESTful to deliver Images for APEX

   Who doesn't want things to be faster.  Here's a very easy way to get images in the database out faster.  The normal way to get images embedded into and Application Express app is to use apex_util.get_blob.  It's tried and test and optimized for doing just that so you may assume it doesn't get faster to get images served out.  Here's a quick screenshot of loading a test page in chrome of 2 identical images and by identical, I mean the same BLOB from the same table with the same ID.

The shorter timeline is the RESTful delivery.  Mileage will of course vary by load and latency but with what I've tested REST delivery is always faster.



For 5 reloads this was the timings I got:


apex_util REST % Faster
  
259             137     89.05%
362             311     16.40%
250             129     93.80%
245             130     88.46%
269             126     113.49%
  


Now introducing RESTful type of Media Resource which makes this very easy to do.  Colm initially blogged about it a while back.  In a nutshell, it's a query that wants 2 columns the first being the content type , mime, and the second being a lob or anything to be delivered.  Colm showed how to deliver XML in his post.  This is how to serve up images.


In the URI Template, you'll notice {id} which is the ID of the image to be served and used as a bind to query.  The select is quite simple to follow.



The table for this example is quite simple but obviously could be anything as long as there's a mime and lob to deliver.


CREATE TABLE  myimages
   ( IMAGE_ID NUMBER NOT NULL ENABLE, 
 IMAGE_BLOB BLOB NOT NULL ENABLE, 
 IMAGE_MIMETYPE VARCHAR2(255)
   )
/