[news.eclipse.tools.emf] Re: Attaching cdo adapters takes long time

[Víctor Roldán Betancort <vroldan@xxxxxxxxxxxxxxxx>]

Guys,

I've created the following bug:

https://bugs.eclipse.org/bugs/show_bug.cgi?id=289371
Provide Dynamic content prefetching mechanism upon CDOResource load

to gather the requirements for this new prefetching mechanism.

From what I understand from Ekke's post, a big chunk of a CDOResource 
should be gathered upon load to reduce server round-trips while 
transferring Revision data. Is this right?

My doubt here is how different is that from the already provided 
prefetching mechanisms. See:

org.eclipse.emf.cdo.view.CDORevisionPrefetchingPolicy
org.eclipse.emf.cdo.session.CDOCollectionLoadingPolicy
org.eclipse.emf.cdo.view.CDOView.Options.getRevisionPrefetchingPolicy()

My initial idea is to provide some custom options that can be passed 
through:

org.eclipse.emf.ecore.resource.Resource.load(Map<?, ?>)

Please, post your thoughts about this new feature in the bugzilla.

Cheers,
Víctor.


Eike Stepper escribió:
> Hi Ekke and Flo,
>
> I understand your need for such prefetching (I think this is the term 
> for what you seem to need). In your case you seem to want to load whole 
> resources in one chunk and that should be possible with comparingly 
> little effort. However, as the responsible for the prosper of an open 
> framework I wonder if the new requirements should be broadened a bit to, 
> e.g., enable the specification of prefetch rules per EClass or so. I'm 
> aware that this is not exactly what you need and maybe it's generally 
> inadequate. At this stage I'd just like to start a requirements 
> discussion ;-)
>
> Cheers
> /Eike
>
> ----
> http://thegordian.blogspot.com
>
>
>
> ekke schrieb:
> > Florian Pirchner schrieb:
> > > Hi Simon,
> > >
> > > it would be great if you can tell me where i can find the logic in 
> > > the cdo server which loads the model and decides what to load / 
> > > transfer.
> > >
> > > So i can write a patch and contribute a solution. Otherwise it is not 
> > > really possible to use cdo in our project, because we have to reduce 
> > > the network latency for our encapsulated models.
> > >
> > > Thanks, Flo
> > some additional infos:
> >
> > We're using EMF to store Business (SWT) Views.
> > This is done by redView (Riena EMF Dynamic Views for Business 
> > Applications)
> > redView will be open-sourced soon (EPL)
> >
> > redView supports all SWT Widgets + some Nebula and uses Riena Ridgets 
> > with (Eclipse) Databinding
> >
> > redView contains a WYSIWYG editor to be used from inside IDE
> > and redView also works from RCP clients where complete business views 
> > are rendered dynamically
> > based from EMF models
> >
> > Our redView's are deep trees and of course if a user opens a Business 
> > View this should be fast ;-)
> >
> > Flo spent much time to make redView run using CDO and it works great:
> > some RCP clients have redViews open, then the 
> > Business-View-Admin(Designer) does some design-changes
> > using redView's WYSIWYG editor from inside Eclipse IDE and after 
> > saving them to CDO server - the changes
> > are immediately visible to the users :-)
> > before using CDO the redViews (XMI) are part of a plug-in and after 
> > changing something, the admin
> > had to update one bundle from OSGI console and to refresh some others 
> > to provide the new views -
> > using CDO this is much easier and an eye-catcher demonstrating this :-)
> >
> > If all RCP clients are working in a local network then CDO works fast,
> > but many clients may be working from other cities using high-speed DSL 
> > connection -
> > and in these cases CDO fails :-(
> > it takes a long long time to open a View. While opening the view we 
> > have to iterate over all objects
> > and this causes much network-traffic and consumes too much time.
> >
> > Its great that CDO scales with large models, does lazy loading etc. 
> > and there are many use-cases where
> > this works well and perhaps is the main reason to use CDO.
> >
> > But in our use-cases we have the need to iterate over all objects and 
> > we know that our model fits
> > into memory, because its a single business (SWT) view ;-)
> >
> > I can imagine that there are many uses-cases where EMF is used with 
> > models where these models
> > have to be completely loaded at once over a network connection. 
> > loading step-by-step and only 1-level deep
> > doesnt work in these cases.
> >
> > We have to find a soulution to load a model at once from CDO server - 
> > otherwise I have to cancel
> > the use of CDO, because of performance slowdown
> >
> > so it would be great if Flo can get enough information to know where 
> > to patch CDO -
> > I really like the concepts of CDO and think its not an un-common 
> > use-case to need a whole
> > emf model from CDO server at once
> >
> > thx for any help
> >
> > --
> >
> > ekke (ekkehard gentz)
> > independent software-architect
> > senior erp-consultant
> > eclipse | osgi | equinox | mdsd | oaw | emf | uml
> > max-josefs-platz 30, D-83022 rosenheim, germany
> > mailto:ekke@xxxxxxxxxxxxxxxx
> > homepage (de): http://gentz-software.de
> > blog (en): http://ekkes-corner.org
> > twitter: @ekkescorner
> > skype: ekkes-corner
> > Steuer-Nr: 156/220/30931 FA Rosenheim, UST-ID: DE189929490