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The kernel can be started and accessed through the use of Servlet Filter/ContextListeners which are provided as part of the DSpace 2 utilities. Developers don't need to understand what is going on behind the scenes and can simply write their applications and package them as webapps and take advantage of the services which are offered by DSpace 2. Access to the kernel is provided via the Kernel Manager and the DSpace object which will locate the kernel object and allow it to be used. 

/* Instantiate the Utility Class */
DSpace dspace = new DSpace();


/* Access get the Service Manager by convenience method */
ServiceManager manager = dspace.getServiceManager();


/* Or access by convenience method for default services */
EventService service = dspace.getEventService();

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The DSpace Services Framework is a backporting of the DSpace 2.0 Development Groups work in creating a reasonable and abstractable "Core Services" layer for DSpace components to operate within.   The Services Framework represents a "best practices" for new DSpace architecture and implementation of exentsions extensions to the DSpace application.   DSpace Services are best described as a "Simple Registry" where plugins.   The DS2 (DSpace 2.0) core services are the main services that make up a DS2 system. These includes services for things like user and permissions management and storage and caching. These services can be used by any developer writing DS2 plugins (e.g. statistics), providers (e.g. Authn), or user interfaces (e.g. JSPUI).

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In DS2 a request is the concept of a request (HTTP) or an atomic transaction in the system. It is likely to be an HTTP request in many cases but it does not have to be. This service provides the core services with a way to manage atomic transactions so that when a request comes in which requires mutliple multiple things to happen they can either all suceed succeed or all fail without each service attempting to manage this independently. In a nutshell this simply allows identification of the current request and the ability to discover if it succeeded or failed when it ends. Nothing in the system will enforce usage of the service but we encourage developers who are interacting with the system to make use of this service so they know if the request they are participating in with has succeeded or failed and take appropriate actions.

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