Introducing the SharePoint Cache Refresh Framework


 

Introduction

 

Although a SharePoint developer should try their best to use the tools that SharePoint provides inevitably the client will ask for something that needs some custom code! Over the last few years the customer has demanded that the code be fast, reliable and scalable.

When this happens one of the first things you start to think about is performance.  Hand in hand with performance is caching so that you can reduce the number of expensive operations.

However, when you cache data you get into scenarios where users make a change but they are not reflected immediately. The users then start complaining because the cache has become stale.

There are a few solutions:-

  • Restart IIS / OWS Timer Service to flush the cache (not practical)
  • Decrease the lifetime of the cache object (increase the number of expensive ops)
  • Use Cache Dependencies to flush the cache

The last option is the best as it supports options when data is being shared across multiple application domains however it doesn’t help when you have a number of servers in your SharePoint farm.

This is why I built the framework. The framework allows you to control the caching of objects across the SharePoint Farm.

The way it works is pretty straightforward and it comes with a small API to allow you to use it in your solutions.

 

Solution Overview

 

The framework is made of a few components:-

  • Cache Configuration SharePoint List to manage the configuration
  • Cache Configuration Refresh Timer Job to perform the cache update
  • Cache Configuration Manager – API to manage the Cache Refresh Configuration
  • Cache Refresh PowerShell Cmdlets to administrate the framework
  • Base Classes for Managing Configuration Objects

The way that the framework work is that an object is cached with a dependency to a particular file on the server’s file system. This uses .NET built in CacheDependencies which run a file watcher against the file. When the file being watched is modified a callback occurs and the cache item is removed from the HTTPRuntime.Cache.

The Cache Refresh Framework provides a method using SharePoint Timer Jobs to run a process which modifies these files across all SharePoint Servers in a farm. This flushes the object from the Cache on each of the servers in the farm so that next time they load the object it is loaded from the Data Access Layer / Storage Mechanism rather than the Cache.

The framework supports multiple cache profiles so that you can group objects to be refreshed together or target them differently.

The following section explains some usages and the process in more detail.

 

Usage

 

The framework can be used to allow caching of objects such as:-

  • Configuration items
  • Navigation items
  • XML elements
  • Plain Old C# Objects (POCO)
  • Data Transfer objects (DTOs)

A common example is:-

  • A user of the system makes a change to the configuration.
  • The SharePoint Application calls into the Cache Refresh Framework tell it to refresh a particular Cache Configuration
  • The Cache Refresh Framework gets the Cache Configuration and runs the timer job for that configuration on all servers in the SharePoint farm using the SharePoint Farm Timer Service.
  • Each server runs the actual job which modifies a file
  • The Cache Dependency picks up the change to the file and flushes the cache
  • The next time the application gets that object it get its from the data access layer rather than the cache.

SharePoint Cache Refresh Framework Diagram

 

 

Deployment, Configuration, How To Examples

 

The framework has been uploaded to Codeplex as the SharePoint Cache Refresh Framework Project and there are a number of guides which cover:-

These can be found in the Documentation Section

 

Finally

 

Currently the framework is an alpha release, so there might be some issues with it, so please don’t try it on your production environment without plenty of testing. There are some known issues and I will look to improve the framework and fix those issues as they are found. However, I am excited about getting the framework out there and getting feedback on it.

If you have any problems, or find bugs then report them on the SharePoint Cache Refresh Framework site using the Issue Tracker forum.

If you have any ideas for additional functionality then please add a Discussion item.

Finally, please let me know if you find it useful and how you have used it!

Thanks

Simon

SharePoint Utility to manage Content Type and List Event Receivers


Introduction

Recently I have been building a solution which makes use of Content Type Event Receivers. The event receivers were being deployed using declarative xml for example:-

<ContentType ID=”[Removed]” Name=”My Content Type” Group=”My Content Types” Version=”0″>
<DocumentTemplate TargetName=”/_layouts/CreatePage.aspx” />
<XmlDocuments>
<XmlDocument NamespaceURI=”http://schemas.microsoft.com/sharepoint/events“>
<Receivers xmlns:spe=”http://schemas.microsoft.com/sharepoint/events“>
<Receiver>
<Name>MyEventHandler</Name>
<Type>ItemUpdated</Type>
<SequenceNumber>10000</SequenceNumber>
<Assembly>MyAssembly, Version=1.0.0.0, Culture=neutral, PublicKeyToken=000000000000</Assembly>
<Class>MyAssembly.EventReceivers.ContentTypeEventReceiver</Class>
<Data></Data>
<Filter></Filter>
</Receiver>
……

Now this normally works great, except when you make a mistake. Its quite well known that upgrading Content Types that have been defined using declarative xml can be tricky.

This is one of the reasons why Microsoft released Feature Upgrades in SharePoint 2010 (if you haven’t seen this then please check out Chris O’Brien’s set of blog posts (http://www.sharepointnutsandbolts.com/2010/06/feature-upgrade-part-1-fundamentals.html) on the subject).

In this case the development was on a SharePoint 2007 environment and I found myself in a situation with deploying Content Type Event Receivers.

It seems that once the Content Type had been deployed and the feature switched on its quite difficult to make certain changes to the content type. This includes changes like the following:-

  • changing a field’s default value
  • changing whether a field is required
  • changing the event receiver definition
    However, unfortunately Gary LaPointe’s stsadm commands would not working correctly for my content type and Gaetan Bouveret’s utility only manages list event receivers but does look very good at that!

Solution

Therefore I started to write my own command line utility. The first version was quickly written to get what I needed to do, done.

I have updated it so that at least its a bit more intuitive but it still only allows you to modify event receivers at a content type or list level.

Please be careful because if you ask it to delete an event receiver then guess what it will delete the event receiver!

As with all these utilities please do not try using this on your production environment without performing some testing on a development environment beforehand.

If you have any comments, problems with the utility please leave a comment and I’ll take a look..

Utility System Requirements:-

  • SharePoint 2007 SP2 (Tested on April 2010 and April 2011 Cumulative Update)
  • Utility must be run from machine which is connected to the SharePoint farm that is being modified.

Usage:-

Console application name: ITSP.EventReceiverConfig.exe

Command Line Arguments:-

  • -url : full url of site that hosts content type or list
  • -mode : [list | add | remove]
  • -targettype : [list | contenttype | assembly]
  • -targetname : [name of list | name of content type | name of assembly]
  • -assembly : [full assembly name including version number etc]
  • -class : [fully qualified class name that is implementing the event receiver]
  • -type : [itemadding | itemadded | itemupdating | itemupdated]
  • -sequence : [number bigger than 1]

The utility with releases, document and source code can be found on Codeplex.

Codeplex Project: http://itspeventreceiver.codeplex.com

Documentation can be found here: http://itspeventreceiver.codeplex.com/documentation

My Bookshelf 2011


Andrew Woodward (@andrewwoody) from 21apps posted a picture of his bookshelf on his company’s site.

His bookshelf is completely different to mine which I am going to take on board and look into in more detail. However, its interesting to hear about what people are reading.

So here is mine (well the ones that I am allowed to have out in the open!) …

simondoy_geek_bookshelf

London SharePoint User Group (Thursday 31st March 2011)


The first London SharePoint User Group of 2011 has been scheduled for Thursday 31st March. Seems like quite a long way away but sure it will be with us very quickly, it seems that 2011 is going to be the fastest year yet!

Sign up at the SharePoint User Group UK site (http://suguk.org/forums/thread/26218.aspx)

P.S Remember to add your full name!

Update

Unfortunately I ended up going on holiday in Scotland instead and couldn’t make the user group however Lee Stevens reviewed the event so although I know I missed out, I got a bit of an idea of what the session was all about.