Our Research Background and Possible Research Directions in the Context of the Adapt Project Davide Rossi Università di Bologna IST

Davide Rossi, Università di Bologna Background Coordination Languages and Models WWW software architectures Coordination on the WWW Distributed Middleware Platforms for Collaborative Distributed Work

Davide Rossi, Università di Bologna J2EE Source: SUN

Davide Rossi, Università di Bologna SWEng and J2EE Components – Java Beans, EJB Middleware – Uniform environments for components – Set of standard services

Davide Rossi, Università di Bologna SWEng and J2EE Patterns – BluePrints – Reference books – SunEdu courses RAD/Visual tools

Davide Rossi, Università di Bologna J2EE Patterns For presentation tier – MVC, helper, … For business tier – Delegation, façade, aggregation, … For integration tier – DAO, activator, …

Davide Rossi, Università di Bologna WebServices A web service is a piece of software made available on the web through the HTTP protocol Based on SOAP Complementary technologies (WSDL, UDDI)

Davide Rossi, Università di Bologna SWEng and WSs Component model Middleware Patterns Modeling language We miss them all (or, at least, we don’t have standards)

Davide Rossi, Università di Bologna WSs: Component Model and Middleware No component model (not even an object model actually) No uniform environment No standard set of services

Davide Rossi, Università di Bologna WSs: Patterns Patterns are primary development tools to take into account non-functional requirements A few patterns are starting to appear in specialized publications They are often very specific

Davide Rossi, Università di Bologna WSs: Modelling Language Orchestration – Composition & coordination – XLANG (Microsoft) – WSFL (IBM) UML – Static description – Activity diagram cannot describe orchestration

Davide Rossi, Università di Bologna XEON An active document is a document that provides some autonomous active behavior XEON is our current implementation of the Active Web architecture XEON is a middleware based on XML that provides an uniform access to all the resources and the services on the Internet XEON extends the interfaces of the XML Document Object Model

Davide Rossi, Università di Bologna XEON ORB DBMSWebLDAP WS Client SOAPCOMCORBA

Davide Rossi, Università di Bologna XEON and Adapt Focus on SOAP access Extend DOM in order to take into account basic services enriched with local properties Define a modeling language (UML extension?)

Davide Rossi, Università di Bologna Jada: a Linda-like coordination toolkit for Java The basic coordination entity is the Space (can either be local or remote) Output to the space: out Associative input from the space: in and read Input operations return a Result object A timeout can be associated to input and output operations

Davide Rossi, Università di Bologna Robustness in Jada No transactions No replication Jada & Adapt – Access as a Web Service – Replication – Transaction support with no ACID properties (?)

Davide Rossi, Università di Bologna X-Folders Distributed folders on users’ sites (the X- Folders) Multiple servents Based on WebDAV X-Folders are reactive (reaction rules based on matching using XPath on resources properties)

Davide Rossi, Università di Bologna X-Folders and Adapt High availability Document replication architecture QoS driven replica selection

Davide Rossi, Università di Bologna WSAP Web Service Access Protocol Used to access server-installed objects Remote method invocation and discovery (like SOAP) Events from server objects to client (unlike SOAP); we use an extension to ECMAScript Server object expose programmatic and graphics interfaces

Davide Rossi, Università di Bologna Summary Web Services and SWEng XEON Jada X-Folders WSAP