Controlling the lifetime of your objects through Dynamite's custom lifetime scopes

For an introduction to container lifetimes, please refer to How to provide your own reusable services through an Autofac registration module before moving on to this article.

If you use the SharePointServiceLocator from Dynamite as a container, you gain access to Dynamite's custom, SharePoint-specific lifetimes:

• InstancePerSite
  • if you want a "singleton per SPSite" behavior - useful to hold state at the site collection level
• InstancePerWeb
  • similar, but "singleton per SPWeb" behavior
• InstancePerRequest
  • the instance will be reused, but only to the time of a single HttpRequest
  • this is a typical use-case in web applications (reuse a DBConnection object to flush it only once at the end of the web request, reuse the result of a large CAML query to display the same content in many web parts in the same page, etc.)
  • to enable this option, you need to activate the Web Application-scope feature "GSoft.Dynamite.SP_Web Config Modifications" - InstancePerRequest requires the deployment of a HttpModule to the web.config.

How to use Dynamite's custom lifetimes

Simply end your type registrations with the lifetime you want:

builder.RegisterType<QuickLinkService>().As<IQuickLinkService>().InstancePerSite();

As always, since you're declaring shared objects through InstancePerSite() and ```InstancePerWeb()``, you need to be aware of concurrency issues.

The hierarchy of lifetime scopes

It is critical to understand that objects which has a per-site, per-web or per-request lifetime can never be resolved from a root application container.

To enable the site, web and request lifetimes, Dynamite's SharePointServiceLocator maintains a hierarchy of lifetime scopes (a hierarchy of parent and child containers, if you will).

It's throgh those site-specific, web-specific and request-specife lifetime scopes that objects with the custom lifetimes (InstancePerSite, InstancePerWeb and InstancePerRequest) will be resolved and their state shared for a longer-than-transient lifetime.

The parent-child hierarchy of lifetime scopes maintained by Dynamite looks like this: