Sakai Architecture Charles Severance / Glenn Golden University of Michigan

Sakai Deliverables Tool Portability Profile - A book on how to write Sakai-compliant services Tool Functionality Profile - A book on the features of the Sakai-developed tools Sakai Technology Release - O/S LMS –Sakai Technology Framework –Sakai Tools and Services –Integration, QA, and Release Management

CHEF 2 Changes uPortal replaces Jetspeed –Enhanced to support the (jsr 168) Portlet 1.0 standard CHEF component framework (backed by Spring) replaces Turbine –Service Locator and Dependency Injections supported (IoC type 2,3) –OSID Loading supported Services Design Pattern unchanged OKI OSIDs and full reference / production implementations Current CHEF services deprecated or re-packaged as new OSIDs –still available for legacy support –compatible with the new OSID services (i.e. Agent = User) New Tool Design Pattern –Based on Java Server Faces New component Packaging –Based on Java Web Applications –Hot deploy of tools & service components

Sakai: Thorny Issues How to handle many repositories (Dspace, Fedora, JSR- 170) though one API? How to store information in a way that is both efficient/fast and flexible/reusable - perhaps RDF/URI is a unifying approach to finding and reusing content? How to take the OKI APIs and add sufficient detail (out- of-band-agreements) so as to make it clear how to write tools? How to make AUTHZ scalable, fast, portable, and interoperable?

Federated Interfaces OKI/Sakai Tool I Local DR API Federated DR API DSpace DR API DB Fedora DR API FedoraDSpace …

Use an Object Store? Tool AUTHZAUTHNDRAPI Object Store RDF/URI External Portfolio Tool

Use RDBMS? Tool AUTHN RDBMS AUTHZDRAPI RDF/URI ???? External Portfolio Tool

RDBMS + “RDF” APIs Tool AUTHN RDBMS RDF/URI External Portfolio Tool AUTHZDRAPI Until we are sure based on development experience - this will be TBD - One thing for sure - we will not sacrifice performance for architectural elegance

“Out-Of-Band Agreements” Tool AUTHZAUTHNDRAPI Object Store OKI does not specify many schema details for lots of objects to maintain flexibility. The OKI API leaves these details to be worked out between the tool developers and the OSID implementers. The Sakai project will decide on these schema-like issues and publish them. But dealing with schema’s directly is often painful and leads to thick and hard-to-modify tools….

Façade/Schema/Semantic Layer org.sakai AUTHZAUTHNDRAPI Object Store Sakai will define build convenience classes (facades …) which enforce semantic details of the Sakai out-of- band agreements on the OKI APIs. Not all OKI APIs will have facades, Applications will be able to communicate directly with the OKI APIs as necessary, the façade mapping may not always be one-to-one. Specs like IMS and LOM will influence these schema decisions within Sakai. The goal is to keep tools easy, clean, and portable. Because the façade classes use OKI APIs, they can move into non- Sakai OKI compliant environments. Tool org.sakai

Tools Tool Pattern Service APIs Services Pattern Service Component Service Component Service Component Service Component Component Framework ServletPortletJSP Application Configuration 2 TomcatuPortal Access Navigation Portal Navigation Tool Resources (jsp, css, png. …) Tool Framework (CHEF enhanced JSF) JSF

Service Design Pattern Separation of concerns –Tools to handle user interactions –Services to handle specific functional, business logic, data type modeling responsibilities Dependent on interfaces, not implementations –Clients dynamically bound to implementations by API Major service or manager API with most methods Supporting core interfaces for the data entities modeled Implemented by many different components Services Pattern

Service API OKI OSIDs –Rich common services CHEF 1.x Services –Higher level feature specific –Becomes OSIDS, merges with the OSIDS New high level (org.sakai.) OSIDS –Packaged with new feature sets / tool suites Service APIs

Component Framework Container for all service components, possibly for tool components Support many design styles –Service Locator - a component manager to find dependent service components by api name –Injection - (IoC type 2, 3) - support for auto-wiring and configuration through bean setters and constructors Life-style and Lifecycles –shared instance, instance per thread, instance per usage –init and destroy methods, possibly others… Configuration driven –Component selection for each API –Configuration values Component Framework

Service Components Implement one service API and related core interfaces Dependent on other service APIs Implement other aspects –Authorization, Event tracking, etc. Implementation choices –POJO (“plain old java object”) –Resolve dependencies via Injection or Locator –J2EE Enterprise Beans Selected and configured by the application Service Component

Application Configuration Select a service component for each needed Service API Configure each component Multiple configurations - many packages Hot modify configurations (w/ new package deployment) Application Configuration

Tools Orchestrates user interaction –Present user interfaces (Views) –Process user requests –Tracks interaction state Responsible for an area of functionality –Chat, Announcements, Schedule, Resources … Java classes –designed to the Tool Pattern Static file resources –png, css, jsp, etc. Heavy lifting done by services –Common services –Custom services –Dependent on service API, not implementations Tools

Tool Design Pattern Based on Java Server Faces Support abstract high level UI components –button, menu, text field, alert, table … Support action model Support view selection Support interaction state Support multiple user agents (browsers) & skins –different renderers Configurable by placement instance –portal Achieve our goal of cross tool interface consistency & Skins Tool Pattern

tool_bean get…() set…() processAction…() view RenderService API (OSID) GUI: Java Server Faces

Tool Framework To support the tool design pattern Based on Java Server Faces Extended with our own special –UI Components –Renderers Extensions classes to Servlet and Portlet Utilities Third party packages (velocity, JSF, etc). Tool Framework

Navigation Like Tools, present UI and handle requests Getting around to specific tool instances –Tools organized in “spaces”: Sites –Multiple tools per “page”: Portal –Other modes Portal Navigation Access Navigation –URL access to resources. Access Navigation Portal Navigation

Packaging Based on standard java Web Applications –.war files Tool, Tool Suite Service Components No code change to add new package Possible Hot Deploy

Standards Servlet JSP Portlet JSF ServletPortletJSPJSF

Portal Engine uPortal 3 –Enhanced with Portlet support Support for others possible – standard Portlet (JSR 168) portal engines –Open Source (i.e. Jetspeed 2) –Commercial (i.e. WebSphere) Portlet uPortal

Portlet + Servlet Model Portlets for navigation, tool placement, tool configuration, usage sessions Servlets for popups and popins –Tool content without the portal decorations –New windows, iframes in portal windows Servlets for JSF –“included” from the standard CHEF JSF portlet Servlets for other navigations –Access, authentication, management, etc. Servlet Portlet

Summary We have a long way to go and a short time to get there… The team we have assembled is the key - each institution brings deep and complimentary skills to the table Previous collaboration (Navigo, OKI) over the past few years has developed respect, teamwork, and trust from the first day of Sakai We are taking some time at the beginning to insure genuine consensus and that we truly make the right choices in the framework area. We understand that we may make mistakes along the way and have factored this into our apprach and resource allocation. So far everyone has had an open mind and understands the “good of the many…”