BeJUG - Spring 3 talk

Spring Framework 3.0Alef Arendsen

•Configuration options in 1.0, 2.0, 2.5 and 3.0• Introduction of REST support in Spring MVC•Migration of OXM from WS to Spring Framework• Introduction of expression language support•Other features and considerations for Spring 3.0

Agenda

<?xml version="1.0" encoding="UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="...">

<constructor-arg ref="dataSource"/> </bean>

</beans>

Spring 1.0 <beans/> schema

<?xml version="1.0" encoding="UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:tx="http://www.springframework.org/schema/tx" xsi:schemaLocation="...">

<tx:annotation-driven base-package="org.springframework.samples.petclinic"/>

</beans>

Spring 2.0 schema support

@Transactional @Repositorypublic class HibernateClinic implements Clinic { private SessionFactory sessionFactory;

@Autowired public HibernateClinic(SessionFactory sessionFactory) {

this.sessionFactory = sessionFactory; }}

Spring 2.5 annotations

<?xml version="1.0" encoding="UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context" xsi:schemaLocation="...">

<context:component-scan base-package="org.springframework.samples.petclinic"/>

</beans>

Component scanning

@Controllerpublic class ClinicController {

private final Clinic clinic;

@Autowired public ClinicController(Clinic clinic) { this.clinic = clinic; }

@Controller for Spring MVC

@Controllerpublic class ClinicController {

@RequestMapping("/vets") public List<Vet> vets() { return clinic.getVets(); }}

@RequestMapping methods

Constantly simplifying

•LoC for sample application PetClinic over time

Spring 2.5Spring 2.0

Spring as a foundation

•Other technologies building on the Spring foundation

•Spring Batch 2.0 (e.g. with @BatchComponent)•Spring Integration 1.0 (e.g. with @MessageEndpoint)•Spring Web Services (e.g. with @Endpoint)•...

•Most projects feature annotation-based options as well as XML-based ones

Other portfolio example: Spring Integration 1.0 - dec08

•Relatively new project under the Spring Portfolio umbrella

• Focuses on in-VM lightweight integration scenarios–asynchronous messaging in a single VM–with adapters for many formats to integrate with external systems (JMS, Email, File, et cetera)

• Implement of the Patterns of Enterprise Application Integration (Hohpe et. al.)

@MessageEndpointpublic class OrderSplitter {

@Splitter(inputChannel="orders",outputChannel="drinks")

public List<OrderItem> split(Order order) { return order.getItems(); }}

@MessageEndpoint

<si:splitter input-channel="orders" output-channel="drinks" ref="orderSplitter" method="split" />

@MessageEndpoint

public class OrderSplitter {

public List<OrderItem> split(Order order) { return order.getItems(); }}

Look ma, no annotations!

New in Spring 3.0

•Previously available in a separate project(Spring JavaConfig)

•Has been available in prototype form since early 2005

•Now promoted to the coreSpring Framework

<?xml version="1.0" encoding="UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="...">

<constructor-arg ref="dataSource"/> </bean>

</beans>

Spring 1.0 <beans/> schema

@Configurationpublic abstract class MyConfig { @Bean public Clinic clinic() { DataSource ds = dataSource(); return new JdbcClinic(ds); }

@Autowired public abstract DataSource dataSource();

JavaConfig in Action

One method per bean

Agenda

• (Ideally) stateless server architecture•Resources•Actions / operations on those resources•Representations

Summary of REST

A practical example

•http://bank.com/account/1234•Represents the account resources

–GET retrieves the account•GET to bank.com/account/1234 to retrieve

–PUT creates or modifies a resource•Post to bank.com/account/1234 to create/update

–POST creates a resource•Post to bank.com/account to create a new account

–DELETE deletes a resources•DELETE to bank.com/account/1234 to delete or for example deactiveate / cancel

Summary of Spring REST

•URI template support (client & controller)•Support for representations

(HTML, XML, RSS, Atom, PDF, Excel, JSON)•Servlet Filter to PUT/DELETE support•Built on Spring MVC

@Controller@RequestMapping("/account/*")public class AccountController { @RequestMapping(value="/*/{id}",

method=RequestMethod.GET) public Account get(@PathVariable long id) { // retrieve and return account }}

Support for URI templates

Handles URL: http://bank.com/account/1234

Representations

•Neatly laid-out support for several representations of your data:–HTML (e.g. through FreeMarker or JSPs)–PDF and Excel (POI, JExcelApi, iText)–JSON, RSS, Atom–XML

•Support for changing the representation based on extension or the accept-header

Support for PUT and DELETE

•Most browsers don’t support PUT / DELETE•So what about the following:

@RequestMapping(value="/*/{id}", method=RequestMethod.DELETE) public void delete(@PathVariable long id) { // delete account }

Support for PUT and DELETE

•Most browsers don’t support PUT / DELETE•So what about the following:

•Support for PUT and DELETE is added through a special ServletFilter (and in HTML for example using a hidden input field)

@RequestMapping(value="/*/{id}", method=RequestMethod.DELETE) public void delete(@PathVariable long id) { // delete account }

•Recap of Spring 2.5 configuration options and @MVC

• Introduction of REST support in Spring MVC•Migration of OXM to Spring Framework• Introduction of expression language support•Other features and considerations for Spring 3.0

Agenda

•Mapping objects to XML and vice versa through–XmlBeans, JiBX, Castor, JAXB (2), XStream

•Used to be part of Spring WS•Useful for REST purposes as well•Moved to core Spring Framework as of 3.0

Object-XML mapping abstraction in Spring

public interface Marshaller { public void marshal(Object graph, Result result) throws XmlMappingException, IOException;}

Interfaces for marshalling and unmarshalling

public interface Unmarshaller { public Object unmarshal(Source source) throws XmlMappingException, IOException;}

• JMS (MarshallingMessageConverter•MVC (MarshallingView)•Batch• ...

Usages throughout portfolio

•Recap of Spring 2.5 configuration options and @MVC

• Introduction of REST support in Spring MVC•Migration of OXM from WS to Spring Framework• Introduction of expression language support•Other features and considerations for Spring 3.0

Agenda

Property externalization in 2.5

•Traditionally using

<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource"

destroy-method="close"> <property name="driverClassName" value="${driver}"/> <property name="url" value="${url}"/> <property name="usernane" value="${username}"/> <property name="password" value="${password"/></bean>

<context:property-placeholder location="/WEB-INF/jdbc.properties"/>

Drawbacks of this approach

• It only supports properties•The replacement is done at initialization

time»Not at bean creation time

• It doesn’t support conditionals or other constructs

• It’s not very extensible for other frameworks

Introducing expressions

•Spring 3.0 will include full support for the unified expression language

•The replacement is done when the bean is created (and not when reading the configuration)

Introducing expressions

•Spring 3.0 will include full support for the unified expression language

•The replacement is done when the bean is created (and not when reading the configuration)

<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource"

destroy-method="close" scope=”prototype”> ...

Using expressions in other parts of the portfolio

•An extensible expression language•Will be used by other frameworks

–Security (example below)–Integration / JMS (e.g. dynamic queue names)–Et cetera

@PreAuthorize("hasRole('ROLE_SUPERVISOR') or " + "hasRole('ROLE_TELLER') and " + "(#account.balance + #amount >= -#account.overdraft)" ) public void post(Account account, double amount);

• Recap of Spring 2.5 configuration options and @MVC• Introduction of REST support in Spring MVC• Migration of OXM from WS to Spring Framework• Introduction of expression language support• Other features and considerations for Spring 3.0

Agenda

Backwards compatibility

•Spring 3.0 will deprecate / remove various things

•Traditional Spring MVC controller hierarchy (??)•Commons Attributes support•Traditional TopLink support•Traditional JUnit 3.8 class hierarchy

•95% backwards compatible with regards to APIs

•99% backwards compatible in the programming model

•Spring 3.0 M1 released in December•Spring 3.0 M2 to be released any time now•Further Milestones later this quarter•Spring 3.0 RC and release Q2 2009

•More information on what features are included in which milestones: http://jira.springframework.org

Roadmap

Questions?

BeJUG - Spring 3 talk

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