Warning – this post is somewhat techie so if you’re not a developer you may want to go find something more interesting to do!
I’ve been doing some work with SharePoint Feature Receivers recently and found the official documentation to be somewhat … lacking.
SharePoint Feature Receivers allow you to run code when a Feature such as a web part or template is installed, activated, deactivated and removed. They are often used for installation/setup tasks that can’t be done using XML incantations in Manifest.xml, Elements.xml and Feature.xml.
I am not going to give a step-by-step guide to Feature Receivers (see the excellent How to add a Feature Receiver to a Feature from SharePoint dev wiki) but plan to detail information that I was struggling to find anywhere else.
I am only going to cover the scenario of a Feature encapsulated in a solution package and not installing features directly using STSADM -o InstallFeature as that requires the files are manually placed in the 12\Template\Features\ directory so is not as friendly as distributing .wsp files and is not something that you can really give to customers/server admins.
SharePoint Features can be targeted at the Farm, Web Application, Site Collection or Web Site scope. The target will effect things like where you can manage the feature activation from in the UI and at which point (and how many times) the Feature receiver events are called.
|Scope||Activate/Deactivate Features (2007)|
|Web Site||Site Actions > Site Settings > Site Administration > Site features|
|Site Collection||Site Actions > Site Settings > Site Collection Administration > Site collection features|
|Web Application||SharePoint Central Admin > Application Management > SharePoint Web Application Management > Manage Web application features|
|Farm||SharePoint Central Admin > Operations > Global Configuration > Manage farm features|
SharePoint Feature lifecycle
|Stage||Event||Trigger with STSADM -o||Trigger with UI|
|Add to solution store||AddSolution|
|Deployment to server/farm||FeatureInstalled||DeploySolution||Central Admin > Operations > Solution Management|
|Activation to SCOPE||FeatureActivated||
|See scope table above|
|Upgrade||FeatureUpgrading (new for 2010)||UpgradeSolution|
|Deactivation from SCOPE||FeatureDeactivating||
On RetractSolution if still activated when called
|See scope table above|
|Retraction from server/farm||FeatureUninstalling||RetractSolution||Central Admin > Operations > Solution Management|
|Delete from solution store||DeleteSolution|
SharePoint Administration Timer Jobs
Deployment and Retraction actually setup a timer job (which can be executed ‘immediately’ or at a specified time. If the “Windows SharePoint Services Administration” Service is not running then you will be warned that these jobs will not be executed and you can force execution by running STSADM -o ExecAdmSvcJobs on all servers in your farm.
You can’t be sure which windows identity a feature event receiver will be running under as you don’t know if it will be called by STSADM (cmd.exe), “Windows Share Services Administration” timer service (WSSADMIN.EXE) or the WebUI (w3wp.exe with the app pools identity) – so ensure you are not relying on privileges (for example) that may be given to a logged on domain admin when using STSADM but not the app pools identity.
|Triggered with STSADM||Triggered by UI|
|FeatureInstalled||Logged on user||Identity of Web Applications Application Pool.|
Identity of “Windows SharePoint Serviecs Administration” service
or Logged on user if forcing by STSADM -o ExecAdmSvcJobs
|FeatureUninstalling||Logged on user||Identity of Web Applications Application Pool.|
Because you can’t be sure where the FeatureReceiver is being called from (command line, timer service, web ui) you can’t use the normal method of getting a SPSite/SPWeb object.
SPSite site = SPContext.Current.Site;
SPWeb web = SPContext.Current.Web;
Note – you only get a SPFeatureRecieverProperties.Feature reference with FeatureActivated and FeatureDeactivating – its null for Installed and Uninstalling.
|Scope||FeatureActivated and FeatureDeactivating|