Re: caching

[Charles Yates]

 It uses DeltaTimeCacheValidity which accepts a time value in its
constructor:
http://xml.apache.org/cocoon/apidocs/org/apache/cocoon/caching/DeltaTimeCacheValidity.html

   The CacheableSource creates one of these in its constructor,  and
CacheableSourceFactory keeps a java.util.Map associating urls with
CacheValiditys that are in the cache.  The two are compared to decide
whether or not to refresh the cache as well as what to return for
getLastModified().  At the moment the time value is hard coded
(I'm using 15 minutes).
    I did consider using a Generator to do this, and to be honest, I've
forgotten why I abandoned that effort.
Charles

Reinhard Pötz wrote:

Charles,

Nice to hear this!

One question: How do you set the cache validity time e.g. 60 minutes if
you use a source?
Regards,
Reinhard
 

-----Original Message-----
From: Charles Yates [mailto:[EMAIL PROTECTED] 
Sent: Thursday, February 27, 2003 2:56 PM
To: [EMAIL PROTECTED]
Subject: Re: caching

   I am curently testing a 'CacheableSource' and 
'CacheableSourceFactory' that does these things. Its not 
ready for prime time yet but it does do the things mentioned 
here.  Used like this:

cache://http://www.unreliableserver.com/news.rdf
cache://cocoon://resource/that/takes/a/long/time
  It uses DeltaTimeCacheValidity.  If the validity has 
expired, it returns the resouce from the cache and updates it 
in another thread.

   I'll report back when its ready.

Charles

Carsten Ziegeler wrote:

   



     

-----Original Message-----
From: Reinhard Pötz [mailto:[EMAIL PROTECTED]
Sent: Thursday, February 27, 2003 12:39 PM
To: [EMAIL PROTECTED]
Subject: RE: caching
  

       

From: Carsten Ziegeler [mailto:[EMAIL PROTECTED] Reinhard Pötz 
wrote:
    

         

Do you know whether there is some mechanism to get the old
          

               

(=expired)
        

             

content if the external source is not available after it
          

               

expired?
  

       

No, it's not possible.
        

             

At which 'level' would you solve that problem? Would you write a 
special generator?

      

           

Yes, exactly.

But I'm not sure if this is a good solution. If the 
         

external source 
   

is not available, you usually get a timeout (4 or 5 minutes?). So, 
you have to wait for this timeout and then serve from the 
         

cache; this 
   

time is too long for the casual user.

I would suggest that you always serve from the cache even if the 
content has expired. If it has expired you will the cache in the 
background. This can be done in a special generator as well.
    

         

Am I right you would write a background component that tries to 
refresh all expired content of the cache and until it is 
       

updated the 
   

'old' version could be used.
  

       

Yes.



     

Would this fit in the already existing "pipeline-expires" and 
"pipeline-caching" concepts?

  

       

This would be two different parts, so the
caching algorithm works as always and your generator does 
     

his work. Of 
   

course, your generator can be still cacheable and used by 
     

the caching 
   

pipeline.

Carsten

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