The Sitecore Pie
At some point I want to catalog the full set of features a Sitecore Content Delivery and Content Management server can manage in a project. My goal would be to identify all the elements that can be split apart into independent services. This post is not a comprehensive list of those features, but serves to introduce the concept.
Think of Sitecore as a big blueberry pie that can be sliced into constituent parts. Some Sitecore sites can really benefit from slicing the pie into small pieces and letting dedicated servers or services manage that specific aspect of the pie. Too often, companies don’t strategize around how much different work their Sitecore solution is doing.
An example will help communicate my point: consider IIS and how it serves as the execution context for Sitecore. Many implementations will run logic for the following through the same IIS server that is handling the Sitecore request for rendering a web page. These are all slices of the Sitecore pie for a Sitecore Content Delivery server:
- URL redirection through Sitecore
- Securing HTTP traffic with SSL
- Image resizing for requests using low-bandwidth or alternative devices
- Serving static assets like CSS, JS, graphics, etc
- Search indexing and query processing (if one is using Lucene)
If you wanted to cast a broader net, you could include HTTP Session state for when InProc mode is chosen, Geo-IP look-ups for certain CD servers, and others to this list of pie slices. Remember, I didn’t claim this was an exhaustive list. The point is: IIS is enlisted in all this other work besides processing content into HTML output for Sitecore website visitors.
Given our specific pie slices above, one could employ the following alternatives to relieve IIS of the processing:
- URL Redirection at the load balancer level can be more performant than having Sitecore process redirects
- Apply SSL between the load balancer and the public internet, but not between the IIS nodes behind your load balancer — caled “SSL Offloading” or “SSL Termination”
- There are services like Akamai that fold in dynamic image processing as part of their suite of products
- Serving static assets from a CDN is common practice for Sitecore
- Coveo for Sitecore is an alternative search provider that can take a lot of customer-facing search aspects and shift it to dedicated search servers or even Coveo’s Cloud. One can go even further with Solr for Sitecore or still other search tiers if you’re really adventurous
My point is, just like how we hear a lot this election season about “let Candidate X be Candidate X” — we can let Sitecore be Sitecore and allow it to focus on rendering content created and edited by content authors and presenting it as HTML responses. That’s what Sitecore is extremely valuable for.
Enter the Cache
I’ve engaged with a lot of Sitecore implementations who were examining their Sitecore pie and determining what slices belong where . . . and frequently we’d make the observation that the caching layer of Sitecore was tightly coupled with the rest of the Sitecore system and caching wasn’t a good candidate for slicing off. There wasn’t a slick provider model for Sitecore caches, and while certain caches could be partially moved to other servers, it wasn’t clean, complete, or convenient.
That all changed officially with the initial release of Sitecore 8.2 last month. Now there is a Sitecore.Caching.DefaultCacheManager class, a Sitecore.Caching.ICache interface, and other key extension points as part of the standard Sitecore API. One can genuinely add the Sitecore cache to the list of pie slices one can consider for off-loading.
In my next post, I will explore using this new API to use Redis as the cache provider for Sitecore instead of the standard in-memory IIS cache.