[Ovirt-devel] [R&D] Breaking the Browser

[Jeff Schroeder]

On Thu, Jul 3, 2008 at 2:14 PM, Jason Guiditta <jguiditt at redhat.com> wrote:
> On Thu, 2008-07-03 at 13:59 -0700, Jeff Schroeder wrote:
>
>> Q: How do you get realtime graphs with a webapp?
>> A: SVG + AJAX
>>
>> A good example of how to do this would be the m0n0wall firewall.
>> Here is a screenshot of their interface graphs:
>> http://m0n0.ch/wall/images/screens/status_graph.png
>>
>> The svg graphs are drawn by the javascript. It gets the data from a
>> xmlhttprequest
>> feed directly from the server. It is really sexy technology and most browsers
>> support it. Is asking IE users to install the Adobe SVG plugin or user Firefox
>> too much?
>>
>> Take a look at how easy this is to do:
>> http://www.browserland.org/scripts/svgclock/
>>
>> If you compress that svg down, the whole thing is 4k. I don't even think flash
>> could do something that smooth and clean looking in 4k. Were you aware of this?
>>
> Agreed, and we are using svg for the graphs right now, though they do
> need some optimization and better javascript hooks.  I am not a
> proponent of us using flash for this, but others disagree.  Also, since
> adobe is discontinuing support for their svg viewer, there is another
> one I have read good things about called renesis:
> http://www.examotion.com/Downloads.product_player_download.0.html

Besides internet explorer, a better question would be why not use
javascript + svg?
If someone that isn't you disagrees, can they give a solid technical
reason for this?

What graph _absolutely has to be_ realtime? In all of the cases I
could come up with
not a one wouldn't be serviced by near-realtime graphs. Do you expect
users to have
ovirt graph screens up on a bank of plasma displays watching node
stats in realtime?
Even in a big fortune 100 NOC this seems unreasonable and a bad use case.

Once oVirt a policy engine (like VMotion) the graphs updating in
realtime don't seem
near as useful. Can you think of a reason that demands absolute realtime graphs?

Here is how I envision oVirt with a 2-3 major releases under it's belt.

AMQP bus message:  OH NOES, Node3 is about to bust out the oom killer to lay the
                                 smack down on vm1 and vm2. Run
around, scream, and panic!
oVirt Policy Engine:    Live migrates vm1 and vm2 from Node3 to Node4
because Node4 is idle.
AMQP bus message:  Disaster diverted by policy engine. All systems nominal.
oVirt Policy Engine:    Goes back to saving the world and drinking it's latte
Systems Admin:         Hey look at that, something bad almost happened but this
                                 cool software fixed itsself. /goes
back to reading xkcd

What do you think?

-- 
Jeff Schroeder

Don't drink and derive, alcohol and analysis don't mix.
http://www.digitalprognosis.com