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[protege-discussion] preloading of Instances in Protege 3.3 (411) ?

Timothy Redmond tredmond at stanford.edu
Tue Jul 3 15:35:52 PDT 2007


> I tried to load instances of class Person and a maximum of 5000 instances with
> these parameters:
>
> server.client.preload0=Person 
> preload.frame.limit=5000
This is the key to this issue.  There are two reasons why this is not 
working for you.

First, we have explicit code on the server that says to ignore instances 
in the server-client caching scheme.   The reason for this is that for 
large OWL ontologies, there are classes which defeat the preload 
mechanism if their instances are loaded.  Thus the instances of 
owl:Restriction can be a very large set (think 50,000+) and preloading 
all of this is very expensive.  Some possible easy fixes for this are 
either (1) ignoring the instance constraint in frames based ontologies 
or (2) having a -D option that enables caching of instances.  I think 
that this problem is relatively easy to fix.  We just need  to figure 
out what we want.

We have a second problem though that is more difficult.  The 
server-client caching scheme has some explicit optimizations for 
deciding what needs to be in the client cache next.  So in your case, 
you not only need to cache the fact that the Person class has a certain 
set of instances but you also need to cache information about each of 
these instances.  If you only cache the set of instances for the Person 
class, then when the client wants to display the instance (or do 
something else with the instance) it will have to go back to the 
server.  We have direct experience with this and it can be very costly.

We are committed to solving  the second problem also but it is a little 
trickier.  We need to make the algorithm that decides what to cache next 
be a plugin.  This will allow us to deal with applications such as the 
Protege collaborative tab which defeat the current client-server caching 
scheme.  For  the collaborative tab, the server does not know how to 
predict future requests for information from the annotation tab.  Once 
this is a plugin it will be very easy to arrange that instance data is 
preloaded.

I am hoping that we can look at this in more detail for the next beta 
release.

-Timothy




Jens wrote:
> Hi again,
> sorry for my "spamming" of the list today. I have collected several topics
> and I want them sorted out in individual mails.
>
> My hopefully last question today is, how do I configure preloading of
> Instances in Protege frames. As I use client-server mode, is this preloading
> configured on the server, on the client or both?
>
> I tried to load instances of class Person and a maximum of 5000 instances with
> these parameters:
>
> server.client.preload0=Person 
> preload.frame.limit=5000
>
> Starting the client, it says something about preloading, but it does not do
> anything. Adding the parameters to Protege.lax and/or protege.properties Files
> have no effect.
>
> What can I do? system properties on Windows should bei in Protege.lax, right?
>
> Regards,
> Jens.
>
> Console-output starting the Protege client:
> --------------------------------------------------------
> CONFIG: Loaded plugin uk.ac.man.cs.mig.coode.owlviz
> CONFIG: Loaded plugin uk.ac.man.cs.mig.coode.protege.wizard - Basic Wizards
> CONFIG: Loaded plugin uk.ac.man.cs.mig.coode.protege.wizard.owl - OWL Wizards
> CONFIG: Preloading frame values
> CONFIG: Preloading frame values
> WARNING: Missing map instance: onto_db_tst_ProjectKB_Instance_210578 -- Property
> MapUtil.getMap()
> WARNING: null -- WidgetUtilities.isSuitableExport()
> WARNING: null -- WidgetUtilities.isSuitableExport()
> CONFIG: Preloading frame values
> CONFIG: Preloading frame values
> CONFIG: Preloading frame values
> CONFIG: Preloading frame values
> CONFIG: Preloading frame values
> CONFIG: Preloading frame values
> INFO: Connected to server chat project on server.
> INFO: UI display time = 4 sec
> --------------------------------------------------------
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