[GRLUG] Headerless website rendering

[Ben DeMott]

Hey Ben,
Imagine opening your browser, installing WebDeveloper Plugin, visiting a
page, and clicking "View Generated Source" and saving it to a text file.
This is what I am doing server-side with no browser or client involved,
completely from the execution of a program.

Let me be more specific, I'm not talking about server-side ECMA script
execution, I'm talking about Emulating a Browser Engine - Server side
programatically.
It is pretty difficult to simulate the exact manner in which your browser
renders, displays, arranges, re-orders, event listens, parses the DOM when
received from a server not to mention how your browser handles redirects,
forwards, headers, meta tags - on and on.

It would (In my opinion) be a bad idea for me to attempt to replicate the
behavior of a Browser in any fashion by attempting to execute Javascript /
ECMA script server side.  If you could for example get a Javascript (jquery)
library to act upon a DOM server-side or you know of a way I would be very
interested to know about it.

In addition when you interact and execute Javascript using a Browser engine
(Gecko, or Webkit) you have programmatic access to the execution,
callbacks/events, the dom itself, and lots of other stuff that you normally
wouldn't by just running server-side Javascript.

The more interesting part of this was to actually render screenshots of
webpages as a browser does in a Virtual Framebuffer.

Believe it or not, I'm using this code now for debugging purposes in my
web-development and the possabilities are endless :)

I hope this better explains what I am doing...

On Wed, Jun 3, 2009 at 1:12 PM, Ben Rousch <brousch at gmail.com> wrote:

> On Wed, Jun 3, 2009 at 12:48 PM, Ben DeMott <ben.demott at gmail.com> wrote:
>
>> For those that might be interested ...
>>
>> Recently for work I told a customer that wanted headerless execution
>> (server side) of Javascript that I "Couldn't do it".
>> Now over the last few years I've looked into the subject a few times,
>> always being quite pessimistic about it.
>>
>> Over the last year I've been doing iPhone development and using the WebKit
>> API - Using the Cocoa api you can "headerlessly" execute a web page by just
>> not drawing the display buffer to the screen.
>> Awhile after this customer asked for completely programmtic headerless
>> rendering I had some free time so I looked back into the issue.  Knowing
>> that the WebKit api can be accessed in such a way for this to be
>> "theoretically" possible I pushed on...
>>
>> And that is when I came across Nokia's API - the Qt ('cute') API has
>> WebKit support amongst many other things, and actually after working with
>> the iPhone SDK I feel pretty at home using it.
>> It's an event driven api, written in C++ ...
>>
>> After researching the Qt library a bit, I found that it had Python
>> bindings (even better) and it's most recent version supported a very modern
>> version of WebKit similar to what Safari uses.
>>
>> I then started looking for a way of actually 'drawing' the webpage, I knew
>> that if I could draw to a Frame Buffer I could probably programatically on a
>> server save and render images of web pages.
>>
>> After quite a lot of work I came across the work of several other
>> individuals that had used the same process involving Qt - Although the code
>> was a bit poorly implemented.
>>
>> I took concepts from several of the resources I found and wrote a python
>> application that uses Xvfb (the X Virtual Frame Buffer) to render a web
>> page, on a server.
>> All you need is Python, pyQt4, Xvfb, (a script called Xvfb-run that
>> supposedly comes with Xvfb, but I had to install manually) and a Linux
>> distro in a 2.6 kernel variant.
>> I have it working very well on a Fedora 9 distro with the apps listed
>> above, if anyone is interested in my code example, or further instructions
>> let me know and I'll throw it up on a website.
>>
>> And all of this was sadly to crawl google results (google re-orders and
>> dynamically controls results with Javascript client side, including business
>> results)
>> If anyone wants the PHP functions that parse google (using DOM) let me
>> know ...
>> Along with this (sadly - I'm not proud of this) I wrote a Google Image
>> results parser...
>>
>> Customers are mad, because the code will obviously break when google makes
>> any changes but it was quite the experiment in code :) ... and I got paid
>> for it.
>>
>> The image code was to (help) find logo's for companies / organizations.
>> Garmin's data provider (InfoUSA) tracks 13,000 franchises/organizations
>> the system had about an 80% success rate on those organizations - check out
>> an example here.
>>
>> (type in a company name, like 'mcdonalds')
>> http://apginc.net:8380/binja/test_image_query.php
>>
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>
>
> I may be a bit dense here, but I'm not sure about what you mean by
> "headerless". There are several ways to execute javascript server-side:
> http://en.wikipedia.org/wiki/Server-side_JavaScript
>
> Or are you "viewing" web sites by saving them to an image or something?
>
>
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