Thursday, March 17, 2011

Monitoring with Images and Slugs

After my Blogging Jeopardy! post,  John Piwowar recommend I use FeedBurner to better keep count of my audience. My blind spot is aggregators. I'm very happy to have my content aggregated, and it goes out through OraDBPedia, OraNA, OraFAQ and probably some others too. Those aggregators pick up my feed, extract the records (content and metadata, such as author and date posted) and merge it into their feed. And people pick up that merged feed without ever touching the original feed, and that's where I lose track of them.

But images are magic. In an RSS feed, images are just a URL. The actual image data has to picked up by the end viewer. My images go through Picasa, as all my blog/website stuff is tied up in Google. Picasa tells me that an image in a recent post of mine was downloaded about 400 times, indicating that post had about that many viewers.

A similar tactic is exploited by mass mailers. When your email client talks about blocking remote content, it is probably talking about images, though Javascript libraries and CSS files are another, more dangerous, culprit. But outside of the security aspect, the email client  warns you about 'privacy'. That is because there is a good chance that the image is being used to track whether you opened the email.

If I do a mass email to Tom, Dick and Harry, I can include a unique image URL in each one, in the same way as I address them individually with Dear Slug. I'll obfuscate it a bit to hide the fact, but essentially I'll have src="" If Tom wants to see the image, he has to get the content by calling the URL which tells me that Tom's message has been opened.

In my Oracle focussed world, I'd have one table of 'email templates' (with the HTML text and image data as CLOB and BLOB respectively), one 'subscriber' table with names and email addresses, and an 'email' table representing the many-to-many between the two. The email table would have the personalized URL. I'd use the Apex Listener to supply images in the same way as I did for PDFs, but this time I'd use a procedure. The listener calls the procedure, which picks the email via the personalized URL, marks it as read and then returns the actual image data from the parent email template.

If anyone wants an itty-bitty Apex app for that, let me know through a comment (or twitter, email or LinkedIn...) (maybe we should call it 11gR2d2) added SSL for UTL_SMTP, making it a better option for sending out emails. Whether the XE version will have that remains to be seen. Anything I have would use the old, unencrypted technique.

If anyone doubts the approach of having the image data in the database, I can recommend Marcelle's ODTUG webinar on "Audio & Video Management Using PL/SQL". The ODTUG webinars are recorded and you get the URL if you are registered for the webinar. Not sure if I'm allowed to post the URL, but you could ask Marcelle.

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