1. EJBs +XML + Integrity Constraints Data-Object Modeling and Optimization (DOMO) June 2003 Rajesh Bordawekar, Michael Burke, Mukund Raghavachari, Vivek Sarkar, Oded Shmueli

2. A Changing Application Environment Frameworks such as Container-Managed Persistence simplify integration of application logic with databases.  Programmer specifies mapping between Java classes and schema declaratively.  Relational databases have integrity constraints.  XML schemas have integrity constraints.  Application logic may have its own integrity constraints.  There is no mechanism for reasoning about constraints on data given a mapping between language types and relational schema.  Applications may fail when seemingly correct updates are rejected by the database.  Domain constraints and referential integrity constraints. Need to reason about such constraints.

3. Setting db.X. t ejb.X.t Mapping Mapping associates db.X. t and ejb.X.t T → What can be deduced about db originated values based on the schema? XML data Relational data

4. EJBs + XML Current J2EE implementations provide little support for XML data sources. Goals:  Understand integration of XML and EJBs.  Efficient algorithms for instantiating EJBs from XML data sources. E.g., Streaming algorithms.  Focus: Mechanisms for ensuring that XML (and relational) integrity constraints are maintained in application logic. Past Work:  Streaming algorithms for XPath (ICDE 2003).

5. XML Data Bindings XML data is “imported” into the application environment. Often, the data conforms to an XML schema or a DTD. XML schemas support constraints: domain, uniqueness, key. These should be related to relational database and application constraints. Data travels in both directions (“export”).

6. Plans Examine data binding formalisms. Examine XML schema constraints. Analyze their interplay at the application level:  Support static analysis of programs to determine constraint violations.

7. Example: Updating a “ Record" EJB Field SAL is updated in an employee record. SAL is associated with min=10K, max=200K. Two salary ranges: [10,45], [65,200]. May check application code to determine possible violations.

8. Record XML Schema Complex type Union type Restriction

9. Use Cases Reading a database record Writing/Updating a database record Reading an XML element/attribute Writing/Updating an XML element/attribute Assisting CMP/BMP Assisting CMR

10. Using Constraint/Type Information Constraints for the same application may originate in a relational DB, an XML schema, a DTD or other sources. We therefore need to reason about and manipulate constraints originating in various formalisms. Analyze program statically and dynamically to verify that constraints are met.  Failure of a check implies update will fail in DB. Success usually provides no definite information.  Much related Dist. DB literature on the subject.

11. XAOS: XPath Analysis and Optimization for Streaming Xpath-specific Automaton supports streaming XPath processing for forward and backward axes XPath Expression XML Parser XML Document Xpath-specific Automaton Specialized XPath Processor XML Fragments Parsing Events Motivation: XPath lookup is next major bottleneck in XML processing (after parsing) Streaming access is most efficient mode for memory hierarchies and large documents

12. XAOS Example XPATH expression //y[u]//w[ancestor::z/v] XML Document Xpath-specific Automaton Parser + Specialized XPath Processor Root(0) X (1) Y(10) Y(2) Z(11) Z(4) U(9) W(12) V(5) V(6) W(7) W(8) W(3) U(13) Root(0) Y(2) Z(4) U(9) V(5) V(6) W(7) W(8) XDAG: Y Y U U W W V V Z Z Root descendant child descendant Root Y Y Z Z U U V V W W XPath Matchings in XML Document

13. XAOS Scalability: Parsing + XPath Execution times Experiments run on 550 MHz Pentium III, w/ 256MB RAM & Linux 2.2