Poche chiacchiere e tanto codice per cercare rendere la nostra vita di sviluppatori più divertente. Parleremo di JAX-RS, le annotazioni, l'MVC che mette a disposizione e l'integrazione di Jersey con Guice. Useremo AOP per gestire log, transazioni e con l'aiuto di Infinispan limiteremo le chamate concorrenti sul nostro cluster.

1. Jersey + Guice + AOP
Domenico Briganti
dometec@gmail.com

2. Chi sono?
@PerRequest
public class Presentation {
@GET
@Path("/JugMilano/People/DomenicoBriganti")
@Produces(MediaType.APPLICATION_JSON)
public Response getUserDetails() {
UserDetails userdet = new UserDetails();
userdet.setCompany("Eidon srl");
userdet.setEmail("dometec@gmail.com");
userdet.setLinkedin("http://www.linkedin.com/in/dometec");
userdet.setBlog("http://tipsaboutmywork.blogspot.com/");
...
return Response.ok(userdet).build();
}
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3. Agenda
JAX-RS
Jersey con Guice/AOP
Demos:
Log delle richieste
Trim dei parametri Stringa in ingresso
Evitare chiamate identiche su un cluster
Transazioni
Login cookie
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4. JAX-RS
Java API for RESTful Web Services
Release 1.1, JSR 311, 2009, JEE6 Full
Release futura 2.0, JSR 339, (EDR2 2012), JEE7
Package: javax.ws.rest
Implementazioni: Jersey (RI), Apache CXF,
RESTEasy, Apache Wink
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5. Jersey
Open source, RI for JAX-RS
Jersey 1.x (1.13b1) implements JAX-RS 1.1
Jersey 2.x (mileston 3) implements JAX-RS 2
CDDL + GPL 1.1
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6. Jersey Hello World
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.core.Response;
@Path("/hello")
public class HelloWorldService {
@GET
@Path("/{param}")
public Response getMsg(@PathParam("param") String msg) {
String output = "Echo: " + msg;
return Response.ok(output).build();
}
}
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7. JAX-RS Annotation
Verbi HTTP: @GET, @POST, @PUT, @DELETE,
@OPTION, @HEAD
Identificazione risorse: @Path
Input: @PathParam, @QueryParam, @MatrixParam,
@HeaderParam, @CookieParam. @FormParam.
@DefaultValue. MultivaluedMap<String, String>
Content negotiation: @Produces, @Consume
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8. JAX-RS Annotation e Facility
Ambiente: @Context (ServletConfig, ServletContext,
HttpServletRequest, HttpServletResponse,
SecurityContext, UriInfo, HttpHeaders)
Mapper, MessageBodyWriters,
MessageBodyReaders: @Provider
ResponseBuilder e UriBuilder
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9. DEMO 0
“Esecuzione” della
slide di presentazione
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10. Jersey-Guice integration
<listener>
<listener-class>org.example.demo.GuiceConfig</listener-class>
</listener>
<filter>
<filter-name>GuiceFilter</filter-name>
web.xml:
web.xml
<filter-class>com.google.inject.servlet.GuiceFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>GuiceFilter</filter-name>
<url-pattern>/services/*</url-pattern>
<url-pattern>/application.wadl</url-pattern>
<url-pattern>/application.wadl/*</url-pattern>
</filter-mapping>
package org.example.demo;
public class GuiceConfig extends GuiceServletContextListener {
@Override
listener
protected Injector getInjector() {
return Guice.createInjector(new JerseyServletModule() {
@Override
protected void configureServlets() {
Map<String, String> params = new HashMap<String, String>();
params.put(PackagesResourceConfig.PROPERTY_PACKAGES, "org.example.demo");
params.put(ResourceConfig.FEATURE_TRACE, "true");
params.put(ResourceConfig.FEATURE_TRACE_PER_REQUEST, "true");
...
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11. Demo 1
Log delle richieste
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12. Demo 1 – Log delle richieste (interc.)
public class LogCall implements MethodInterceptor {
public Object invoke(MethodInvocation invocation) throws Throwable {
Logger logger = LoggerFactory.getLogger(invocation.getThis().getClass());
String arg = Joiner.on(", ").useForNull("null").join(invocation.getArguments());
logger.debug("{} ({}).", invocation.getMethod().getName(), arg);
Object result = invocation.proceed();
logger.trace("Output: {}.", result);
return result;
}
}
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13. Demo 1 – Log delle richieste (bind)
public class GuiceConfig extends GuiceServletContextListener {
@Override
protected Injector getInjector() {
return Guice.createInjector(new JerseyServletModule() {
@Override
protected void configureServlets() {
Map<String, String> params = new HashMap<String, String>();
params.put(PackagesResourceConfig.PROPERTY_PACKAGES, "org.example.demo");
...
filter("/*").through(GuiceContainer.class, params);
install(new Module() {
public void configure(Binder binder) {
LogCall logCall = new LogCall();
TrimAndNullInterceptor trimAndNullableInterceptor = new TrimAndNullInterceptor();
bindInterceptor(
Matchers.annotatedWith(Path.class),
Matchers.annotatedWith(GET.class).or(Matchers.annotatedWith(POST.class))
.or(Matchers.annotatedWith(PUT.class)).or(Matchers.annotatedWith(DELETE.class)),
trimAndNullableInterceptor, logCall);
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14. Demo 2 – Trim parametri (interc.)
public class TrimAndNullInterceptor implements MethodInterceptor {
public Object invoke(MethodInvocation invocation) throws Throwable {
for (int i = 0; i < invocation.getArguments().length; i++) {
if (invocation.getArguments()[i] != null &&
invocation.getArguments()[i] instanceof String) {
String sparam = (String) invocation.getArguments()[i];
String trim = sparam.trim();
if (trim.isEmpty())
invocation.getArguments()[i] = null;
else
invocation.getArguments()[i] = trim;
}
}
return invocation.proceed();
}
}
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15. Demo 2 – Trim parametri (bind)
public class GuiceConfig extends GuiceServletContextListener {
@Override
protected Injector getInjector() {
return Guice.createInjector(new JerseyServletModule() {
@Override
protected void configureServlets() {
Map<String, String> params = new HashMap<String, String>();
params.put(PackagesResourceConfig.PROPERTY_PACKAGES, "org.example.demo");
...
filter("/*").through(GuiceContainer.class, params);
install(new Module() {
public void configure(Binder binder) {
LogCall logCall = new LogCall();
TrimAndNullInterceptor trimAndNullableInterceptor = new TrimAndNullInterceptor();
bindInterceptor(
Matchers.annotatedWith(Path.class),
Matchers.annotatedWith(GET.class).or(Matchers.annotatedWith(POST.class))
.or(Matchers.annotatedWith(PUT.class)).or(Matchers.annotatedWith(DELETE.class)),
trimAndNullableInterceptor, logCall);
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16. Evitare richieste duplicate
Problemi:
Ristrasmissioni
Doppi submit (anche Tripli...) da browser
Timeout lato client che scatena altre prove di richieste
Rimedi:
Hashtable con chiamate attualmente in corso
429 Too Many Requests (RFC 6585)
Infinispan con lock condiviso per sistemi cluster
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17. Demo 3 – Richieste duplicate (uso)
@POST
@UniqueCallOnCluster
public Response getAccountBalance(@FormParam("fromuser")...
@POST
@UniqueCallOnCluster
public Response getAccountBalance(@KeyParameter
@FormParam("fromuser")...
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18. Demo 3 – Richieste duplicate (Inter.)
public class UniqueCallOnClusterInterceptor implements MethodInterceptor {
...
public Object invoke(MethodInvocation invocation) throws Throwable {
String classname = invocation.getMethod().getDeclaringClass().getSimpleName();
String methodName = invocation.getMethod().getName();
String key = classname + "_" + methodName + "_" + extractParameterValue(invocation);
TransactionManager tm = keyCallOnClusterService.getTransactionManager();
tm.begin();
boolean success = keyCallOnClusterService.lock(key);
if (!success) {
logger.info("Non posso effettuare il lock sul cluster per la chiave {}.", key);
return Response.status(429).entity("Another call with same parameter is in progress.").build();
}
String runningServer = (String) keyCallOnClusterService.get(key);
if (runningServer != null) {
logger.info("Chiamata già in corso, server {}.", runningServer);
return Response.status(429).entity("Another call with same parameter is in progress.").build();
}
keyCallOnClusterService.put(key, "todo-hostname");
tm.commit();
...
return invocation.proceed();
...
keyCallOnClusterService.remove(key);
}
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19. Demo 3 – Richieste duplicate (bind)
public class GuiceConfig extends GuiceServletContextListener {
@Override
protected Injector getInjector() {
return Guice.createInjector(new JerseyServletModule() {
@Override
protected void configureServlets() {
Map<String, String> params = new HashMap<String, String>();
params.put(PackagesResourceConfig.PROPERTY_PACKAGES, "org.example.demo");
...
filter("/*").through(GuiceContainer.class, params);
install(new Module() {
public void configure(Binder binder) {
UniqueCallOnClusterInterceptor uniqueCallOnClusterInterceptor =
new UniqueCallOnClusterInterceptor();
requestInjection(uniqueCallOnClusterInterceptor);
bindInterceptor(Matchers.any(), Matchers.annotatedWith(UniqueCallOnCluster.class),
uniqueCallOnClusterInterceptor);
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20. Transazioni con AOP
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21. Transazioni con AOP
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22. Transazioni con AOP
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23. Demo 4 – Transazioni (uso)
package org.example.demo.controller;
@PerRequest
@Transactional
@Path("services/transactionalresource3")
public class TransactionalResource3Write extends AbstractTransactionalResource {
@Inject
public TransactionalResource3Write() {
}
@POST
@Produces("text/plain")
public String get() {
...
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24. Demo 4 – Transazioni (uso)
package org.example.demo.controller;
@PerRequest
@Transactional(TransactionType.ReadOnly)
@Path("services/transactionalresource1")
public class TransactionalResource1ReadOnly extends AbstractTransactionalResource {
@Inject
public TransactionalResource1ReadOnly() {
}
@GET
@Produces("text/plain")
@SuppressWarnings("unchecked")
public String get() {
List<DatabaseLog> list = getSession().createCriteria(DatabaseLog.class).list();
if (list.size() == 0)
return "No record!";
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25. Demo 4 – Transazioni (uso)
package org.example.demo.controller;
@PerRequest
@Transactional(TransactionType.RequiredNew)
@Path("services/transactionalresource5")
public class TransactionalResource5ReqNew extends AbstractTransactionalResource {
@Inject
public TransactionalResource5ReqNew() {
}
...
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26. Demo 4 – Transazioni (uso)
public abstract class AbstractTransactionalResource {
private Session session;
@NoTransactional
public void setSession(Session session) {
this.session = session; }
@NoTransactional
public Session getSession() {
return session; }
@Override
@NoTransactional
protected void finalize() throws Throwable {
super.finalize(); }
}
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27. Demo 4 – Transazioni 1/2 (interc.)
public class TransactionInterceptor implements MethodInterceptor {
private final ThreadLocal<Stack<Session>> sessionThreadLocal;
public Object invoke(MethodInvocation invocation) throws Throwable {
...
Transactional transactional =
invocation.getMethod().getDeclaringClass().getAnnotation(Transactional.class);
...
Stack<Session> sessionStack = sessionThreadLocal.get();
Transaction transaction = null;
Session session = null;
if (!sessionStack.isEmpty())
session = sessionStack.peek();
if (session == null || transType.equals(TransactionType.RequiredNew)) {
boolean readonly = false;
readonly = transType.equals(TransactionType.ReadOnly);
session = hibernateSessionService.openSession(readonly);
transaction = session.getTransaction();
transaction.begin();
sessionStack.push(session);
}
Session oldSession = null;
AbstractTransactionalResource service = ((AbstractTransactionalResource)
invocation.getThis());
oldSession = service.getSession();
service.setSession(session);
Object result = invocation.proceed();
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28. Demo 4 – Transazioni 2/2 (interc.)
try {
Object result = invocation.proceed();
if (transaction != null) {
session.flush();
transaction.commit();
}
return result;
} catch (Exception e) {
transaction.rollback();
throw e;
} finally {
if (transaction != null) {
hibernateSessionService.closeSession(session);
sessionStack.pop();
if (sessionStack.isEmpty())
sessionThreadLocal.remove();
}
service.setSession(oldSession);
}
}
}
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29. Demo 4 – Transazioni (bind)
public class GuiceConfig extends GuiceServletContextListener {
@Override
protected Injector getInjector() {
return Guice.createInjector(new JerseyServletModule() {
@Override
protected void configureServlets() {
Map<String, String> params = new HashMap<String, String>();
params.put(PackagesResourceConfig.PROPERTY_PACKAGES, "org.example.demo");
...
filter("/*").through(GuiceContainer.class, params);
install(new Module() {
public void configure(Binder binder) {
TransactionInterceptor transactionInterceptor =
new TransactionInterceptor();
requestInjection(transactionInterceptor);
bindInterceptor(Matchers.annotatedWith(Transactional.class),
Matchers.not(Matchers.annotatedWith(NoTransactional.class)),
TransactionInterceptor);
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30. Demo 5 - Login Cookie (bind)
Annotation:
AuthenticatedUser
ApplicationRolesAllowed
Provider:
AuthenticatedUserProvider
Exception e ExceptionMapper:
NotAuthenticatedException(+Mapper)
NotAuthorizedException(+Mapper)
Cookie: LoginCookieManager
Utente: DemoPrincipal
Interceptor: ApplicationRolesAllowedInterceptor
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31. Grazie!
Domande??
Riferimenti:
http://jersey.java.net
http://code.google.com/p/google-guice/
Demo webapp:
https://github.com/dometec/shadedcode/tree/master/demo-webapp
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