New Persistence Features in Spring Roo 1.1

1. Chicago, October 19 - 22,
2010
New Persistence Features in
Spring Roo 1.1
Stefan Schmidt

2. Agenda
• Spring Roo’s Approach to Persistence
• Incremental Database Reverse Engineering
• Apache Solr / Lucene Integration
• Alternative Persistence Technologies

3. Spring Roo’s Approach to
Persistence

4. Peristence Choices
• JPA2 for ORM
– 4 choices of ORM providers
• Hibernate
• EclipseLink
• OpenJPA
• DataNucleus (DN1 supported for GAE, DN2 used by VMforce)
• 12+ Database choices
– constantly growning list of DBs to choose from
– popular ones: MySQL, Postgres, HSQLDB (for dev)
• Switch out ORM and / or DB with a single command
– persistence setup --provider HIBERNATE --database MYSQL

5. No DAOs?
• No DAO layer by default
– Objections:
• testing
• separation of concern
• pluggable implementations
• non JPA persistence
• security authorizations
• security auditing
• finders
• architectural reasons

6. Feature Extension Points
• Add-ons can contribute persistence feature extensions via
ITDs
– Finder add-on is a good example
• Every @RooEntity exposes the JPA entity manager
– use for creating custom type-safe queries via Criteria API
– getting access to the underlying ORM

7. Incremental Database
Reverse Engineering

8. Alternatives to Roo’s Incremental DBRE
• Eclipse “JPA Entities from tables” wizard
– Generates entities from a JDBC connection
– Can be tailored to change generated type and field names
– Does not handle tables with no primary keys
• JPA Implementation Tools

9. Limitations of Existing DBRE Tools
• Lack of incremental reverse engineering
• Complex and long-winded wizard style interactions
• Missing entity lifecycle management
– Application requires manual adjustment if the datamodel
changes

10. Introducing Roo’s Incremental Database
Reverse Engineering
• DBRE was the most requested feature for Spring Roo
• Introspect relational databases such as Oracle, MySQL,
PostgreSQL and Microsoft SQL Server
• Reverse engineer complex schemas into Java entities in
seconds
• Creates and maintains relationships with JPA 2.0
annotations
• Incrementally updates your domain model as your DB
schema changes

11. How does DBRE work?
• Uses the standard java.sql.DatabaseMetaData
implementation of your JDK
• Connects to a live database using JDBC and creates
entities from the database metadata obtained
• Similar to the output generated by the Eclipse wizard with
all accepted defaults

12. Spring Roo DBRE Commands
• database introspect --schema <name> [--file <name>]
– Displays database metadata in XML format in the Roo shell
– Optional --file <file name> saves metadata to specified file
– Provides a preview of the mappings used in the final model

13. Spring Roo DBRE Commands
• database reverse engineer [--schema <name>] [--
package <name>]
– Creates entities in the specified package
– --schema and --package options required only for first time
run of command
– Automatically generates type and field names from table
and column names
– JPA-annotated fields and getters/setters saved in AspectJ
ITDs, eg Person_Roo_DbManaged.aj

14. Primary Keys
• Supports single and composite primary keys
– Creates a separate primary key class for tables having more
than one primary key or no primary key (uses all fields for
key)
– Annotates the primary key class with @Embeddable and the
entity's id with @EmbeddedId

15. Entity Relationships
• Automatically creates and maintains bi-directional
relationships:
– @ManyToMany, many-valued associations with many-to-
many multiplicity
– @OneToOne, single-valued associations to other entities
that have one-to-one multiplicity
– @OneToMany, many-valued associations with one-to-many
multiplicity
– @ManyToOne, single-valued associations to other entities
that have many-to-one multiplicity

16. DEMO
Database Reverse Engineering Demo

17. Apache Solr / Lucene
Integration

18. What is Apache Solr?
• Search server
• Built upon Apache Lucene (Java)
• Fast, very
• Scalable, query load and collection size
• Distributed search and index replication
• Interoperable
• Extensible

19. Solr Features
• Powerful full-text search
• Hit highlighting
• Faceted search
• Spell checking
• Dynamic clustering
• Database integration
• Rich document (e.g., Word, PDF) handling.

20. Interacting with Solr
• HTTP GET / POST
• JSON / XML
• SolrJ (embedded over HTTP)
• Ruby: solr-ruby, RSolr
• many others: python, PHP, solrsharp, XSLT
• JMX monitoring available
• Admin interface available

21. Configuring Solr
• schema.xml
– Defines field types
– Can drive more intelligent processing
– Dynamic Fields enable on-the-fly addition of new fields
– CopyField
• indexing a single field multiple ways
• combining multiple fields into a single searchable field
– Many additional text analysis components
• word splitting,
• regex filters
• sounds-like filters

22. Roo Solr Integration
• Roo Shell
– solr setup  install SolrJ driver in project pom.xml
– solr add  make individual type searchable
– solr all  make all JPA entities searchable
• @RooSolrSearchable type annotation
• Hooks into JPA lifecycle
– @PostPersist
– @PostUpdate
– @PreDelete
• Uses SolrJ client

23. Entity Methods Introduced via Roo
• QueryResponse search(String queryString)
• QueryResponse search(SolrQuery query)
• @Async void indexPerson(Person person)
• @Async void indexPeople(Collection<Person> people)
• @Async deleteIndex(Owner owner)
• solrServer is also accessible on target type.

24. DEMO
Apache Solr

25. Alternative Persistence
Technologies

26. Demand for Choice
• ROO-301: Choose between data access patterns
– demand for repository and DAO pattern support
• 70+ votes in Spring Roo Jira, second most popular issue
– Spring JDBC template
– demand for iBatis support (ROO-452)
– demand for NoSQL integration
– demand for polyglot persistence

27. Hades Add-On
• Have you heard of Hades project?
– Utility library to work with Data Access Objects
• implemented with Spring and JPA
– Main goal is to ease the development and operation of a
data access layer in applications
• Installation in the Roo shell with a single command:
– addon install --bundleSymbolicName org.synyx.hades.roo.addon
– hades setup
– hades repository --entity ~.domain.Person
– more features planned (finders, DDD, etc)

28. DEMO
Hades Add-On

29. Summary
• Roo has deep and rich persistence support
• Roo’s Incremental DBRE feature is the next generation in
DBRE capabilities
• Solr and Incremental DBRE offer devs a major
productivity boost
• Alternative persistence technologies supported and
expanding