[Engine-devel] [UX] how to design a bar/line chart?

Tomas Jelinek tjelinek at redhat.com
Tue Nov 12 15:21:15 UTC 2013 


----- Original Message -----
> From: "Alexander Wels" <awels at redhat.com>
> To: "Tomas Jelinek" <tjelinek at redhat.com>
> Cc: engine-devel at ovirt.org, "Michal Skrivanek" <michal.skrivanek at redhat.com>, "Eldan Hildesheim"
> <ehildesh at redhat.com>, "info" <info at eldanet.com>
> Sent: Tuesday, November 12, 2013 4:03:14 PM
> Subject: Re: [Engine-devel] [UX] how to design a bar/line chart?
> 
> On Tuesday, November 12, 2013 09:50:07 AM Tomas Jelinek wrote:
> > ----- Original Message -----
> > 
> > > From: "Alexander Wels" <awels at redhat.com>
> > > To: engine-devel at ovirt.org
> > > Cc: "Tomas Jelinek" <tjelinek at redhat.com>, "Michal Skrivanek"
> > > <michal.skrivanek at redhat.com>, "Eldan Hildesheim" <ehildesh at redhat.com>,
> > > "info" <info at eldanet.com>
> > > Sent: Tuesday, November 12, 2013 3:33:56 PM
> > > Subject: Re: [Engine-devel] [UX] how to design a bar/line chart?
> > > 
> > > On Tuesday, November 12, 2013 09:25:34 AM Tomas Jelinek wrote:
> > > > Hey all,
> > > > 
> > > > let me conclude what has been written in this thread to one proposal:
> > > > 
> > > > == From the UX perspective the behavior ==
> > > > - each time the FE will receive new data and this data are different
> > > > from
> > > > the old ones, visualize it in the chart It means if you will keep
> > > > pressing
> > > > the refresh button but the data will not change, no new data will be
> > > > visualized (an exception will be the 0 usage) - the amount of data
> > > > visualized will depend on the size of the widget (since the tables are
> > > > resizable). It means that if you make the widget bigger you will not
> > > > see
> > > > the same chart bigger but more data. - If you make the widget bigger,
> > > > only
> > > > then the amount of data will start to increase: e.g.
> > > > 
> > > > before resize:
> > > > | /-------\ |
> > > > |
> > > > |/         \|
> > > > 
> > > > after resize:
> > > > | /-------\          |
> > > > |
> > > > |/         \         |
> > > > 
> > > > and only now the new data will start to appear
> > > > 
> > > > == From FE technical point of view ==
> > > > - since I have not found any GWT library which would be acceptable
> > > > (e.g.
> > > > actively developed and without the need to connect to google servers)
> > > > and
> > > > given that the required chart is quite simple I guess it would be ok to
> > > > write it by myself. - according to Einav's mail it is ok to use HTML5
> > > > canvas so I would go with writing a new widget using HTML5 canvas
> > > 
> > > Just to throw out something to think about, we could also in theory
> > > generate an image on the server side and simply display that image inside
> > > the grid (so no need for HTML5 canvas or other things like that). The
> > > idea being basically that when the grid refreshes it makes a request for
> > > a new image on the back- end with the appropriate timeframe and the
> > > back-end generates the image which is easy to embed inside the grid.
> > > 
> > > pros:
> > > * Easy to embed inside grid (just an image tag).
> > > * Works on all browsers, even ones without HTML5 canvas support.
> > > cons:
> > > * More load on the back-end.
> > > * Extra round trips to back-end on refresh.
> > > * Not 'hot' like HTML5 canvas.
> > > * No interactivity if that is something we are interested in.
> > 
> > some more cons:
> > * need to remember the statistics on server in the memory. For thousands of
> > VMs it is not something we would like to do * lots of overhead to retrieve
> > all the images on each refresh. If you have 100 VMs on a page and refresh
> > each 5 seconds, it is 100 images transmitted from engine to frontend each 5
> > seconds per one client (and we can have more of them of course) * FE logic
> > on Server is in general not awesome
> > 
> 
> I would expect the statistics to be stored in the database somewhere, that
> way
> we can pull them for reports and things of that nature (like charts).
> Obviously we wouldn't do 100 round trips for the image, we would generate a
> single image sprite that would contain all the images in a single request and
> display the appropriate part of the image in the grid.
> 
> You are right in general front-end logic is not done on the back-end. However
> we must consider if we are really doing front end logic here, or if we are
> just displaying some reporting information as part of the grid.
> 
> If we are not storing the statistics anywhere, then this is a terrible plan,
> and we should do the logic on the client, but if we are, it is something to
> consider.

We store only the actual value. The statistics are stored only by DWH
but that is a different application. Engine itself does not have it so we would have
to implement it.

> 
> > > > == From L&F point of view ==
> > > > - would look pretty much like the one proposed by Malini:
> > > > http://style.org/chartapi/sparklines/
> > > > 
> > > > == From data point of view ==
> > > > - do not do any averages on VDSM side (since it already does them for
> > > > CPU
> > > > and network and the memory is stable enough) - do not do any averages
> > > > on
> > > > engine side (since would have to be done for each FE separately and
> > > > stored
> > > > in session which is a bit overcomplicated. If the user wants to see
> > > > more
> > > > accurate data, he/she can change the refresh rate) - do not do any
> > > > interpolation since the data are already averaged and we will show only
> > > > new
> > > > ones
> > > > 
> > > > @Malini,Einav,Eldan,Michal what do you think?
> > > > 
> > > > Tomas
> > > > 
> > > > ----- Original Message -----
> > > > 
> > > > > From: "Michal Skrivanek" <michal.skrivanek at redhat.com>
> > > > > To: "Tomas Jelinek" <tjelinek at redhat.com>, "Dan Kenigsberg"
> > > > > <danken at redhat.com> Cc: "Malini Rao" <mrao at redhat.com>, "Eldan
> > > > > Hildesheim" <ehildesh at redhat.com>, engine-devel at ovirt.org, "info"
> > > > > <info at eldanet.com>
> > > > > Sent: Tuesday, November 12, 2013 11:49:12 AM
> > > > > Subject: Re: [Engine-devel] [UX] how to design a bar/line chart?
> > > > > 
> > > > > On Nov 12, 2013, at 11:18 , Tomas Jelinek <tjelinek at redhat.com>
> > > > > wrote:
> > > > > > So we have looked into the resource usage sampling with mbetak and
> > > > > > also
> > > > > > with Michal and it seems that
> > > > > > 
> > > > > > for the CPU usage:
> > > > > > - VDSM polls libvirt to get the runtime statistics of the VM
> > > > > > regularly.
> > > > > > The
> > > > > > pooling interval is configured in
> > > > > > 
> > > > > >  vdsm.conf as vm_sample_cpu_interval and by default it is 15
> > > > > >  seconds
> > > > > > 
> > > > > > - libvirt returns something we than use to calculate the average
> > > > > > CPU
> > > > > > usage
> > > > > > since the last poll
> > > > > > - engine polls VDSM once in 15 seconds to get the current
> > > > > > statistics
> > > > > > (the
> > > > > > same 15 seconds is just a coincidence and we can not count on this)
> > > > > > - than the frontend polls the engine each 5-60 seconds (depends on
> > > > > > the
> > > > > > refresh rate) and gets the current value from the engine
> > > > > > - the user can press the refresh button anytime to poll the engine
> > > > > > again
> > > > > > 
> > > > > > For network usage:
> > > > > > - it should be pretty much the same as the CPU just the VDSM poll
> > > > > > interval
> > > > > > is configured as vm_sample_net_interval and by default it is 5
> > > > > > seconds
> > > > > 
> > > > > Dan, since we poll only every 15s and cpu info is 15s wouldn't it
> > > > > make
> > > > > sense to change the default for network monitoring to 15s as well?
> > > > > it's 2
> > > > > libvirt rounds trip for nothing really. Or does it serve some other
> > > > > purpose?>
> > > > > 
> > > > > > For memory usage:
> > > > > > - guest agent sends a message to VDSM with the memory usage
> > > > > > regularly.
> > > > > > The
> > > > > > interval is set in ovirt-guest-agent.conf as heart_beat_rate
> > > > > > 
> > > > > >  and by default it is 5 seconds
> > > > > > 
> > > > > > - the actual value sent by ovirt-guest-agent is the actual value at
> > > > > > the
> > > > > > time when the value is sent (e.g. for Linux taken from "cat
> > > > > > /proc/meminfo")
> > > > > > - vdsm is doing no statistics on top of it, just remembers the last
> > > > > > value
> > > > > > taken from ovirt-guest-agent
> > > > > 
> > > > > which is fine, it doesn't change so often and there are typically no
> > > > > spikes
> > > > > 
> > > > > > - the rest of the poling is the same
> > > > > > 
> > > > > > So, visualizing this in some usable form will be quite challenging
> > > > > > ;)
> > > > > > I see the following problems:
> > > > > > - if the VDSM gets the data faster than the engine polls it (and
> > > > > > most
> > > > > > often
> > > > > > it does) than the info in between will be lost.
> > > > > > 
> > > > > >  The question is how big this problem is and if it is worth solving
> > > > > >  (I
> > > > > >  would say not for CPU which are averages but maybe yes for
> > > > > >  memory).
> > > > > >  Other question if there is a way how to solve it since the VDSM
> > > > > >  can
> > > > > >  be
> > > > > >  polled by anyone and it does not really care if someone polls
> > > > > >  it...
> > > > > >  (Michal?)
> > > > > 
> > > > > I'd say not solve it and try to keep it in sync on vdsm side with
> > > > > engine
> > > > > poll, to save unnecessary libvirt calls
> > > > > 
> > > > > > - we can lost some data between frontend<->engine if the polling
> > > > > > interval
> > > > > > of the FE is slower than the polling interval of the engine. This
> > > > > > is
> > > > > > something
> > > > > > 
> > > > > >  not really worth solving because the user can set this according
> > > > > >  to
> > > > > >  the
> > > > > >  level of detail he/she wants
> > > > > 
> > > > > well, you should average the values in engine in case the FE refresh
> > > > > is
> > > > > 
> > > > > >15s. Or add (refresh/15) of them
> > > > 
> > > > It is not that simple since you can have more frontends and not sure if
> > > > it
> > > > would be a good idea to put this into the session...
> > > > 
> > > > > > - since we will get new info once in ~15 seconds, and the polling
> > > > > > of
> > > > > > the
> > > > > > FE
> > > > > > is by default 5 seconds, do we want to do some interpolation? Or
> > > > > > just
> > > > > > show
> > > > > > the
> > > > > > 
> > > > > >  same value 3 times? Or be smart and show only changed values?
> > > > > >  (this
> > > > > >  is
> > > > > >  tricky since there is a chance that it did not change - e.g.
> > > > > >  constant
> > > > > >  0
> > > > > >  mem usage if you have no guest agent)
> > > > > > 
> > > > > > - What if the user starts clicking to the refresh button? Do we
> > > > > > want
> > > > > > to
> > > > > > keep appending the same value if the engine still has only the old
> > > > > > ones?
> > > > > 
> > > > > just add a new line/point every 15s should be ok
> > > > > 
> > > > > Thanks,
> > > > > michal
> > > > > 
> > > > > > Tomas
> > > > > > 
> > > > > > ----- Original Message -----
> > > > > > 
> > > > > >> From: "Tomas Jelinek" <tjelinek at redhat.com>
> > > > > >> To: "Malini Rao" <mrao at redhat.com>
> > > > > >> Cc: "Eldan Hildesheim" <ehildesh at redhat.com>,
> > > > > >> engine-devel at ovirt.org,
> > > > > >> "info" <info at eldanet.com>
> > > > > >> Sent: Monday, November 11, 2013 4:23:09 PM
> > > > > >> Subject: Re: [Engine-devel] [UX] how to design a bar/line chart?
> > > > > >> 
> > > > > >> 
> > > > > >> 
> > > > > >> ----- Original Message -----
> > > > > >> 
> > > > > >>> From: "Malini Rao" <mrao at redhat.com>
> > > > > >>> To: "Eldan Hildesheim" <ehildesh at redhat.com>
> > > > > >>> Cc: "Tomas Jelinek" <tjelinek at redhat.com>, "info"
> > > > > >>> <info at eldanet.com>,
> > > > > >>> engine-devel at ovirt.org
> > > > > >>> Sent: Monday, November 11, 2013 4:15:50 PM
> > > > > >>> Subject: Re: [Engine-devel] [UX] how to design a bar/line chart?
> > > > > >>> 
> > > > > >>> Is this going to fit in a row of a table? Or are we talking of a
> > > > > >>> more
> > > > > >>> detailed view?
> > > > > >> 
> > > > > >> it should fit into one cell of the table
> > > > > >> 
> > > > > >>> ----- Original Message -----
> > > > > >>> From: "Eldan Hildesheim" <ehildesh at redhat.com>
> > > > > >>> To: "Tomas Jelinek" <tjelinek at redhat.com>
> > > > > >>> Cc: "info" <info at eldanet.com>, engine-devel at ovirt.org
> > > > > >>> Sent: Monday, November 11, 2013 8:01:07 AM
> > > > > >>> Subject: Re: [Engine-devel] [UX] how to design a bar/line chart?
> > > > > >>> 
> > > > > >>> Throw this gif into a browser. This is more or less what I
> > > > > >>> thought.
> > > > > >>> Eldan
> > > > > >>> 
> > > > > >>> ----- Original Message -----
> > > > > >>> From: "Tomas Jelinek" <tjelinek at redhat.com>
> > > > > >>> To: "Eldan Hildesheim" <ehildesh at redhat.com>
> > > > > >>> Cc: "Einav Cohen" <ecohen at redhat.com>, "info" <info at eldanet.com>,
> > > > > >>> engine-devel at ovirt.org
> > > > > >>> Sent: Monday, November 11, 2013 12:03:15 PM
> > > > > >>> Subject: Re: [Engine-devel] [UX] how to design a bar/line chart?
> > > > > >>> 
> > > > > >>> 
> > > > > >>> 
> > > > > >>> ----- Original Message -----
> > > > > >>> 
> > > > > >>>> From: "Eldan Hildesheim" <ehildesh at redhat.com>
> > > > > >>>> To: "Einav Cohen" <ecohen at redhat.com>
> > > > > >>>> Cc: "info" <info at eldanet.com>, engine-devel at ovirt.org
> > > > > >>>> Sent: Sunday, November 10, 2013 3:56:57 PM
> > > > > >>>> Subject: Re: [Engine-devel] [UX] how to design a bar/line chart?
> > > > > >>>> 
> > > > > >>>> Hello all,
> > > > > >>>> We use to have a good solution in the period pre-WPF.
> > > > > >>>> A line chart (used to be in flash) that works like a plotter:
> > > > > >>>> The Line Bar (not bar) had a small animation that shifted all
> > > > > >>>> the
> > > > > >>>> bar
> > > > > >>>> to
> > > > > >>>> the
> > > > > >>>> left.
> > > > > >>>> When a new data arrived it just added a new line (to the right)
> > > > > >>>> and
> > > > > >>>> as I
> > > > > >>>> said
> > > > > >>>> before, in parallel it always shifted slowly to the left.
> > > > > >>> 
> > > > > >>> Any chance you still have some screenshot or mockup so I can
> > > > > >>> imagine
> > > > > >>> it
> > > > > >>> better?
> > > > > >>> 
> > > > > >>>> The animation gives the impression that data is streaming and
> > > > > >>>> when a
> > > > > >>>> real
> > > > > >>>> new
> > > > > >>>> data arrives the user gets it very fast.
> > > > > >>>> We have to sync between the animation and the rate of the
> > > > > >>>> arrival
> > > > > >>>> of
> > > > > >>>> the
> > > > > >>>> data
> > > > > >>>> but this is easy.
> > > > > >>>> If we can't find a good framework it can be created from scratch
> > > > > >>>> with
> > > > > >>>> JS,
> > > > > >>>> svg
> > > > > >>>> or canvas.
> > > > > >>> 
> > > > > >>> We need to be careful about what we will use. oVirt is supposed
> > > > > >>> to
> > > > > >>> work
> > > > > >>> on
> > > > > >>> FF
> > > > > >>> 17 [1]
> > > > > >>> but the HTML5 canvas works only since FF23 [2].
> > > > > >>> 
> > > > > >>> @Einav:
> > > > > >>> Is there a chance that we could start support only FF23+ and IE9+
> > > > > >>> (this
> > > > > >>> one
> > > > > >>> is already OK)
> > > > > >>> because of this feature?
> > > > > >>> 
> > > > > >>>> Now regarding its position:
> > > > > >>>> Rollover is good but not enough, we should somehow put it in the
> > > > > >>>> lower
> > > > > >>>> panel
> > > > > >>>> under general or even another tab - (live data).
> > > > > >>> 
> > > > > >>> This is a bit different requirement. The point of this specific
> > > > > >>> is
> > > > > >>> to
> > > > > >>> give
> > > > > >>> a
> > > > > >>> better
> > > > > >>> overview in the main tab. If it will be done we can decide if we
> > > > > >>> want
> > > > > >>> to
> > > > > >>> give
> > > > > >>> more
> > > > > >>> details in sub tabs.
> > > > > >>> 
> > > > > >>>> We could later on have a (live data Tab) in other places as well
> > > > > >>>> like
> > > > > >>>> host,
> > > > > >>>> cluster...
> > > > > >>>> Eldan
> > > > > >>> 
> > > > > >>> [1]: http://www.ovirt.org/Download
> > > > > >>> [2]: http://caniuse.com/#feat=canvas
> > > > > >>> 
> > > > > >>>> ----- Original Message -----
> > > > > >>>> From: "Einav Cohen" <ecohen at redhat.com>
> > > > > >>>> To: "Ewoud Kohl van Wijngaarden"
> > > > > >>>> <ewoud+ovirt at kohlvanwijngaarden.nl>
> > > > > >>>> Cc: "Alexander Wels" <awels at redhat.com>, "Eldan Hildesheim"
> > > > > >>>> <ehildesh at redhat.com>, engine-devel at ovirt.org, "info"
> > > > > >>>> <info at eldanet.com>
> > > > > >>>> Sent: Friday, November 8, 2013 10:50:10 PM
> > > > > >>>> Subject: Re: [Engine-devel] [UX] how to design a bar/line chart?
> > > > > >>>> 
> > > > > >>>>> ----- Original Message -----
> > > > > >>>>> From: "Ewoud Kohl van Wijngaarden"
> > > > > >>>>> <ewoud+ovirt at kohlvanwijngaarden.nl>
> > > > > >>>>> Sent: Thursday, November 7, 2013 11:44:07 AM
> > > > > >>>>> 
> > > > > >>>>> On Wed, Nov 06, 2013 at 11:45:36AM -0500, Alexander Wels wrote:
> > > > > >>>>>> I suppose we need to answer a few questions before we can go
> > > > > >>>>>> into
> > > > > >>>>>> which
> > > > > >>>>>> library is better:
> > > > > >>>>>> 
> > > > > >>>>>> 1. Do we mind sending data over to Google so Google can render
> > > > > >>>>>> images
> > > > > >>>>>> for
> > > > > >>>>>> us.
> > > > > >>>>> 
> > > > > >>>>> I'd say no. Even from a reliability point of view since users
> > > > > >>>>> may
> > > > > >>>>> have
> > > > > >>>>> systems that aren't connected to the internet.
> > > > > >>>> 
> > > > > >>>> +1
> > > > > >>>> 
> > > > > >>>>> (Though I don't know how well oVirt handles this currently.)
> > > > > >>>> 
> > > > > >>>> AFAIK - oVirt is handling it ('it' ==  having no internet
> > > > > >>>> connection)
> > > > > >>>> well.
> > > > > >>>> _______________________________________________
> > > > > >>>> Engine-devel mailing list
> > > > > >>>> Engine-devel at ovirt.org
> > > > > >>>> http://lists.ovirt.org/mailman/listinfo/engine-devel
> > > > > >>> 
> > > > > >>> _______________________________________________
> > > > > >>> Engine-devel mailing list
> > > > > >>> Engine-devel at ovirt.org
> > > > > >>> http://lists.ovirt.org/mailman/listinfo/engine-devel
> > > > > >> 
> > > > > >> _______________________________________________
> > > > > >> Engine-devel mailing list
> > > > > >> Engine-devel at ovirt.org
> > > > > >> http://lists.ovirt.org/mailman/listinfo/engine-devel
> > > > 
> > > > _______________________________________________
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> 
>

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