Output Caching in SharePoint 2010 – It doesn’t work, err it does…

Blog #7 in How I Successfully Upgraded eBay to SharePoint 2010 – See Previous Blog In Series

In my last blog post I made a comment that Output Caching does not work in 2010.  Well, it works, but that's the problem.  SharePoint 2010 has elements that are very poorly designed…but we all knew that didn't we?

What is object caching?  It's an ASP.NET feature that allows the HTML of the page to be cached in the web server's memory and very quickly be presented to the clients (albeit slowly with high latency).  Output caching can be turned on on your publishing sites in the Site Actions, Site Settings page for the site collection.  Again, once turned on, the HTML is cached….this is bad.  Yes, I said it is bad.  Why? 

There is this wonderful control called "PersonalSiteActions".  This control emits javascript directly to the page.  This javascript is specifc to a user.  Wha????   Specifc to a user?  But that means….yep….you got it.  The first person to hit the page will cause the HTML to render and THAT HTML WILL BE CACHED.   What does the rendered HTML look like?  Here it is:

function ctl00_ctl39_SocialNavControl_insertMyProfileMenu() {   
var menus = document.getElementsByTagName('menu');   
if (menus == nullreturn;   
var menu = null;   
for (var i=0, len=menus.length; i<len; i++) {       
if (menus[i].id.lastIndexOf('PersonalActionMenu') != -1) {       
menu = menus[i]; break;        }    }    if (menu == null)   return;   
var elm = document.createElement('ie:menuitem');   
elm.setAttribute('menugroupid', '50');   
elm.setAttribute('description', 'View and manage your profile.');   
elm.setAttribute('text', 'My Profile');   
elm.setAttribute('onmenuclick', 'STSNavigate2(event,'http:u002fu002fwww.blah.org:80u002fsitesu002fmyu002fPerson.aspx?accountname=CONTOSOGIVENSCJ)');   
elm.setAttribute('id', 'ID_MySiteLinksMenu');   

var elm2 = document.createElement('ie:menuitem');   
elm2.setAttribute('menugroupid', '50');   
elm2.setAttribute('description', 'Open your personal homepage');   
elm2.setAttribute('text', 'My Site');   
elm2.setAttribute('onmenuclick', 'STSNavigate2(event,'http:u002fu002fwww.blah.org:80u002fsitesu002fmyu002f')');   
elm2.setAttribute('id', 'ID_MySiteMenu');   

What happens when the next user comes along?  The javascript is CACHED.  When they click on the "My Profile" link, they will go to the GIVENSCJ personal site NOT their personal site.  This is what is know as a non-cache safe control.  One might think that you could just go into the ASPX page and edit this, but NO.  This is inside the PersonalSiteActions control.  One might think, I'll create my own control…well, that's a start, but upon further investigation via reflector, you see that is IMPOSSIBLE.  The control has several permission based checks for if a page is in Shared mode or Personal mode and all kinds of internal methods and properties.  Dead end.

This same problem happens for any control you have written that outputs user specific content.  You must ensure that ALL of your controls are cache safe for the basic out of the box output caching to work.  If you don't want these to be cached, you are goign to have to tell the output cache not to cache those sections.  Now we are customizing the out of the box master pages…YUK.

NOTE:  One other issue with the PersonalSiteActions is the "My Site" link.  Notice how it takes you to the default.aspx page that has the newsfeeds.  How is that your "My Site"???  Really?  The SharePoint team could have kept the branding similar as it just confused the hell out of users when they are navigating in SharePoint 2010.  So what can you do with this? 

  • Change the link where the javascript points
  • Update the page to have a redirect

The only way to change the link for the PersonalSiteActions is to do HTML capture and rewrite (yes we even tried javascript and fancy JQuery – no go!).  You can write an HTTP Handler for this.  What happens if you do this?  Our friend Output Caching is not a friend to HTML rewrite.  It forces the output cache to disable itself.  Output cache minus the quirks in SharePoint 2010, can cause a huge increase in application performance.  Implmenting HTTP redirect forces this off, but it worked as I was able to replace the link to the proper link for the my site

The easiest way to get the "branding" right, was to put on the default.aspx page, a redirect to person.aspx.  Problem solved, output cache saved.

Enjoy,
Chris

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