Stylized line drawing of mark playing the flute

Comment Engine: Round 1

Last week, I mentioned that I was working on a comment engine which uses the Google App Engine for the back end. While the plan is for it to support multiple sites, its main purpose is to be used here on this site.

After some on-and-off hacking over the weekend, I have something that works reasonably well. The App Engine back-end seems to be working perfectly. The front-end (which will sit on this site) is going to be PHP & Javascript.

Here's what works

  • Comments can be submitted and are saved to the Google Datastore.

    • The comment is submitted as JSON-encoded array.
    • The array contains the following fields: author, email, comment, pagename, sitename, & sitekey.
  • Every comment is keyed with a site name, page name, & a unique id.

  • A unique identifier is required to submit a comment. This should prevent comments from being submitted from outside of the hosting page. We'll see how well this part works once it goes live.

  • Comments can be retrieved in the following way (all return values are in JSON format)

    • /get/<sitename> returns all comments for an entire site.
    • /get/<sitename>/<pagename> returns all comments for the specific page on a site.
    • /get/<sitename>/<pagename>/<id> returns a single comment for a page.

What's left to do?

  • Need a way to moderate comments. Deleting comments is the most important. The problem is dealing with the authentication so that only authorized users can moderate.
  • Need a better way to support multiple sites & API keys. Right now, there's just one sitekey for this site and it's hard coded.

What I need to do is sit down and figure out the Users API, create an admin page, and then just use my Gmail account to login.

Let's see it in action

OK, if you're really that excited about it.

Here's an example url:

Click on that link and, as of right now, you're going to see something like this

{"46540": {"comment": "This is a test comment", "pagename": "search-replace-with-vim", "sitename": "", "email": "", "author": "Mark Biek"}}

That's a JSON string that shows a single comment (id 46540) attached to this site ( and the page search-replace-with-vim.

I could also do this to just get back the search-replace-with-vim page comments (although there aren't any other pages right now so this url returns the same thing).

And then I can do this if I just want that one comment with id 46540

I'm not doing anything with the above link yet but it'll come in handy for permanent links to specific comments.

So how does it get used?

It's funny because I think I wrote 3 times more PHP & Javascript code to make use of the comment engine than I wrote Python code for the back-end.

None of the PHP/JS stuff is very complicated.

  • I wrote a couple of classes which use cURL to do the appropriate GET & POST calls.
  • All of the JSON manipulation in PHP is handled via json_encode and json_decode.
  • The Javascript makes heavy use of Prototype and its Ajax library.
  • The form is protected using reCAPTCHA which is completely free and dropped right in using their PHP library.

Most of what's remaining on the PHP side is reorganizing so I can easily attach comments to other PHP-based sites.

So, if all goes well, I should be to have comments available on this site soon.