While writing a data layer based on data stored in a SharePoint list, I implemented the collection as a static singleton that forced refreshes of the data every 15 minutes.
A colleague was doing something similar in a roll-up web part and we started discussing Cache Dependency objects used for the HttpContext. Could this work with SharePoint objects?
No, says "The Kid". But he gave me a good idea.
Therefore, I implemented the SPListItemCacheDependency and SPListCacheDependency objects.
To use the SPListItemCacheDependency:
1: HttpContext.Current.Cache.Add("YourKey",
2: dataToCache,3: new SPListItemCacheDependency(sourceItem),
4: Cache.NoAbsoluteExpiration, 5: Cache.NoSlidingExpiration, 6: CacheItemPriority.Normal,7: null);
To use the SPListCacheDependency:
1: HttpContext.Current.Cache.Add("YourKey",
2: dataToCache,3: new SPListCacheDependency(sourceList),
4: Cache.NoAbsoluteExpiration, 5: Cache.NoSlidingExpiration, 6: CacheItemPriority.Normal,7: null);
To monitor schema changes and property changes as well within the SPList and to decrease the change check poll from 10 seconds to 1 minute:
1: HttpContext.Current.Cache.Add("YourKey",
2: dataToCache,3: new SPListCacheDependency(sourceList, true, true, 60000),
4: Cache.NoAbsoluteExpiration, 5: Cache.NoSlidingExpiration, 6: CacheItemPriority.Normal,7: null);
4 comments:
Will the frequent creation of spsite and spweb objects to check for modifications be a problem?
Any thoughts on the same
Well, that's why you can change the polling period as in the example above. You must obviously do some load testing/tracing to find out what the optimal balance would be for your application. There is always a balance between latest content and performance that needs to be fine tuned. In short - if you have enough traffic on your site to need something like this, then a check every 10 seconds will take very little processing compared to rendering the content from live data on each request.
Hi Tobias,
Wouldnt the OOTB PortalSiteMapProvide's GetCachedListItemsByQuery() method suffice if you need a way to cache queries to a SharePoint list.Let me know your thoughts.
Cheers,
Donnel
Hi Donnel,
The method described in this post ensures that the cache is invalidated when a new item is posted to the list. The problem with caching is that the cache does not refresh when needed but times out instead. This code was used on a SharePoint 2007 public web site in order to cache news articles but allow for instant publishing.
There are several ways of achieving this - this was just one example. Since this was released, we have heaps of interesting cache alternatives such as Velocity.
I haven't seen an update in a while, but it looked very cool in CTP. http://msdn.microsoft.com/en-us/magazine/dd861287.aspx
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