I’m toying with an basic infinispan cluster and I came across a puzzling error.
I’m basically implementing a shared map, holding just one Integer
Here is the code of my service
package sandbox.infinispan.test.service;
import javax.enterprise.context.ApplicationScoped;
import javax.inject.Inject;
import javax.inject.Named;
import org.infinispan.Cache;
#Named("useThisOne")
#ApplicationScoped
public class CounterService implements ICounterService {
private static final String KEY = "key";
#Inject
private Cache<String, Integer> cache;
#Override
public void inc(final int amount) {
this.cache.put(KEY, Integer.valueOf(this.get() + amount));
}
#Override
public int get() {
return this.cache.computeIfAbsent(KEY, k -> Integer.valueOf(0)).intValue();
}
}
Cache is produced with the following:
package sandbox.infinispan.test.config;
import javax.enterprise.context.ApplicationScoped;
import javax.enterprise.context.Dependent;
import javax.enterprise.inject.Produces;
import org.infinispan.configuration.cache.CacheMode;
import org.infinispan.configuration.cache.Configuration;
import org.infinispan.configuration.cache.ConfigurationBuilder;
import org.infinispan.configuration.global.GlobalConfiguration;
import org.infinispan.configuration.global.GlobalConfigurationBuilder;
import org.infinispan.manager.DefaultCacheManager;
import org.infinispan.manager.EmbeddedCacheManager;
#Dependent
class CacheProvider {
#Produces
#ApplicationScoped
private EmbeddedCacheManager defaultClusteredCacheManager() {
final GlobalConfiguration g = new GlobalConfigurationBuilder() //
.clusteredDefault() //
.transport() //
.nodeName(this.getNodeName()) //
.clusterName("infinispanTestCluster") //
.build();
final Configuration cfg = new ConfigurationBuilder() //
.clustering() //
.cacheMode(CacheMode.REPL_SYNC) ///
.build();
return new DefaultCacheManager(g, cfg);
}
}
When there are at least two servers in the cluster, computeIfAbsent fails with
15:48:50,253 ERROR [org.infinispan.interceptors.impl.InvocationContextInterceptor] (jgroups-7,myhostname-14393) ISPN000136: Error executing command ComputeIfAbsentCommand, writing keys [key]: org.infinispan.remoting.RemoteException: ISPN000217: Received exception from otherhostname-44445, see cause for remote stack trace
which drills down to:
Caused by: java.lang.NoSuchMethodException: sandbox.infinispan.test.service.CounterService.$deserializeLambda$(java.lang.invoke.SerializedLambda)
and finally to:
Caused by: java.lang.IllegalArgumentException: Invalid lambda deserialization
at sandbox.infinispan.test.service.CounterService.$deserializeLambda$(CounterService.java:10)
... 68 more
Caused by: an exception which occurred:
in object of type java.lang.invoke.SerializedLambda
If I rewrite my pretty nice fashionable code to the ugly following, it works.
#Override
public int get() {
Integer value = this.cache.get(KEY);
if (value == null) {
value = Integer.valueOf(0);
this.cache.put(KEY, value);
}
return value.intValue();
}
How can I use the pretty computeIfAbsent way of doing things nowadays ?
Eclipse 2018-12, WildFly 14, java 10 on of the dev member of the cluster, CentOs 7, OpenJdk 10, WildFly 14 on the remote cluster member.
Thanks for your help
Solved (kinda)
Thanks to the help I received here, I transformed the lambda into an inner class :
static class OhWell implements Serializable {
static Integer zero(final String t) {
return Integer.valueOf(0);
}
}
#Override
public int get() {
return this.cache.computeIfAbsent(KEY, OhWell::zero).intValue();
}
It works now, but it’s lots less nice than the neat lambda. So I’ll stick to the old-fashioned way – unless someone can think of a better way to do it.
Further results:
The following static inner class with a static method works
static class StaticOhWell implements Serializable {
static Integer apply(final String t) {
return Integer.valueOf(0);
}
}
#Override
public int get() {
return this.cache.computeIfAbsent(KEY, StaticOhWell::apply).intValue();
}
The following non static inner class with a non static method fails :
class NotStaticOhWell implements SerializableFunction<String, Integer> {
#Override
public Integer apply(final String t) {
return Integer.valueOf(0);
}
}
#Override
public int get() {
return this.cache.computeIfAbsent(KEY, new NotStaticOhWell()::apply).intValue();
}
It fails with this error message NotSerializableException: org.infinispan.cache.impl.EncoderCache:
13:41:29,221 ERROR [org.infinispan.interceptors.impl.InvocationContextInterceptor] (default task-1) ISPN000136: Error executing command ComputeIfAbsentCommand, writing keys [value]: org.infinispan.commons.marshall.NotSerializableException: org.infinispan.cache.impl.EncoderCache
Caused by: an exception which occurred:
in field sandbox.infinispan.test.service.CounterService.cache
in object sandbox.infinispan.test.service.CounterService#4612a6c3
in field sandbox.infinispan.test.service.CounterService$NotStaticOhWell.this$0
in object sandbox.infinispan.test.service.CounterService$NotStaticOhWell#4effd362
in field java.lang.invoke.SerializedLambda.capturedArgs
in object java.lang.invoke.SerializedLambda#e62f08a
in object sandbox.infinispan.test.service.CounterService$$Lambda$1195/1060417313#174a143b
Final words (?)
Using a “static lambda” (a static inner class implementing the SerializableFunction interface) worked too
static class StaticSerializableFunction implements SerializableFunction<String, Integer> {
#Override
public Integer apply(final String t) {
return Integer.valueOf(0);
}
}
#Override
public int get() {
return this.cache.computeIfAbsent(KEY, new StaticSerializableFunction()::apply).intValue();
}
And the winner is…
Making the class actually serializable by “transienting” the Cache allows to simply use a method of this class. No need to create an inner class!
package sandbox.infinispan.test.service;
import java.io.Serializable;
import javax.enterprise.context.ApplicationScoped;
import javax.inject.Inject;
import javax.inject.Named;
import org.infinispan.Cache;
#Named("useThisOne")
#ApplicationScoped
public class CounterService implements ICounterService, Serializable {
private static final String KEY = "value";
#SuppressWarnings("cdi-ambiguous-dependency")
#Inject
private transient Cache<String, Integer> cache;
#Override
public void inc(final int amount) {
this.cache.put(KEY, Integer.valueOf(this.get() + amount));
}
#Override
public int get() {
return this.cache.computeIfAbsent(KEY, this::zero).intValue();
}
private Integer zero(#SuppressWarnings("unused") final String unused) {
return Integer.valueOf(0);
}
#Override
public void reset() {
this.cache.clear();
}
}
Thanks all!
According to Unable to deserialize lambda the deserializer needs the actual code to be available. Are you sure that your application is already started on all other nodes in the cluster (the exact same version, including your lambda)?
The computeIfAbsent() sends the lambda directly to the data (and therefore handles the operation using one RPC, instead of first fetching the value and then writing it as the 'ugly code'). In WF, your application lives in a different classloader (module) than Infinispan and that might cause an issue.
Could you try to refactor your lambda into a class and see if you get similar problem? I am not that knowledgeable about WF, so there might be a mitigation for regular classes that is missing for lambdas.
Related
How can we create a multi-tenant application in spring webflux using Mongodb-reactive repository?
I cannot find any complete resources on the web for reactive applications. all the resources available are for non-reactive applications.
UPDATE:
In a non-reactive application, we used to store contextual data in ThreadLocal but this cannot be done with reactive applications as there is thread switching. There is a way to store contextual info in reactor Context inside a WebFilter, But I don't how get hold of that data in ReactiveMongoDatabaseFactory class.
Thanks.
I was able to Implement Multi-Tenancy in Spring Reactive application using mangodb. Main classes responsible for realizing were: Custom MongoDbFactory class, WebFilter class (instead of Servlet Filter) for capturing tenant info and a ThreadLocal class for storing tenant info. Flow is very simple:
Capture Tenant related info from the request in WebFilter and set it in ThreadLocal. Here I am sending Tenant info using header: X-Tenant
Implement Custom MondoDbFactory class and override getMongoDatabase() method to return database based on current tenant available in ThreadLocal class.
Source code is:
CurrentTenantHolder.java
package com.jazasoft.demo;
public class CurrentTenantHolder {
private static final ThreadLocal<String> currentTenant = new InheritableThreadLocal<>();
public static String get() {
return currentTenant.get();
}
public static void set(String tenant) {
currentTenant.set(tenant);
}
public static String remove() {
synchronized (currentTenant) {
String tenant = currentTenant.get();
currentTenant.remove();
return tenant;
}
}
}
TenantContextWebFilter.java
package com.example.demo;
import org.springframework.http.server.reactive.ServerHttpRequest;
import org.springframework.stereotype.Component;
import org.springframework.web.server.ServerWebExchange;
import org.springframework.web.server.WebFilter;
import org.springframework.web.server.WebFilterChain;
import reactor.core.publisher.Mono;
#Component
public class TenantContextWebFilter implements WebFilter {
public static final String TENANT_HTTP_HEADER = "X-Tenant";
#Override
public Mono<Void> filter(ServerWebExchange exchange, WebFilterChain chain) {
ServerHttpRequest request = exchange.getRequest();
if (request.getHeaders().containsKey(TENANT_HTTP_HEADER)) {
String tenant = request.getHeaders().getFirst(TENANT_HTTP_HEADER);
CurrentTenantHolder.set(tenant);
}
return chain.filter(exchange).doOnSuccessOrError((Void v, Throwable throwable) -> CurrentTenantHolder.remove());
}
}
MultiTenantMongoDbFactory.java
package com.example.demo;
import com.mongodb.reactivestreams.client.MongoClient;
import com.mongodb.reactivestreams.client.MongoDatabase;
import org.springframework.dao.DataAccessException;
import org.springframework.data.mongodb.core.SimpleReactiveMongoDatabaseFactory;
public class MultiTenantMongoDbFactory extends SimpleReactiveMongoDatabaseFactory {
private final String defaultDatabase;
public MultiTenantMongoDbFactory(MongoClient mongoClient, String databaseName) {
super(mongoClient, databaseName);
this.defaultDatabase = databaseName;
}
#Override
public MongoDatabase getMongoDatabase() throws DataAccessException {
final String tlName = CurrentTenantHolder.get();
final String dbToUse = (tlName != null ? tlName : this.defaultDatabase);
return super.getMongoDatabase(dbToUse);
}
}
MongoDbConfig.java
package com.example.demo;
import com.mongodb.reactivestreams.client.MongoClient;
import com.mongodb.reactivestreams.client.MongoClients;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.mongodb.core.ReactiveMongoClientFactoryBean;
import org.springframework.data.mongodb.core.ReactiveMongoTemplate;
#Configuration
public class MongoDbConfig {
#Bean
public ReactiveMongoTemplate reactiveMongoTemplate(MultiTenantMongoDbFactory multiTenantMongoDbFactory) {
return new ReactiveMongoTemplate(multiTenantMongoDbFactory);
}
#Bean
public MultiTenantMongoDbFactory multiTenantMangoDbFactory(MongoClient mongoClient) {
return new MultiTenantMongoDbFactory(mongoClient, "test1");
}
#Bean
public ReactiveMongoClientFactoryBean mongoClient() {
ReactiveMongoClientFactoryBean clientFactory = new ReactiveMongoClientFactoryBean();
clientFactory.setHost("localhost");
return clientFactory;
}
}
UPDATE:
In reactive-stream we cannot store contextual information in ThreadLocal any more as the request is not tied to a single thread, So, This is not the correct solution.
However, Contextual information can be stored reactor Context in WebFilter like this. chain.filter(exchange).subscriberContext(context -> context.put("tenant", tenant));. Problem is how do get hold of this contextual info in ReactiveMongoDatabaseFactory implementation class.
Here is my very rough working solution for Spring WebFlux - they have since updated the ReactiveMongoDatabaseFactory - getMongoDatabase to return a Mono
Create web filter
public class TenantContextFilter implements WebFilter {
private static final Logger LOGGER = LoggerFactory.getLogger(TenantContextFilter.class);
#Override
public Mono<Void> filter(ServerWebExchange swe, WebFilterChain wfc) {
ServerHttpRequest request = swe.getRequest();
HttpHeaders headers = request.getHeaders();
if(headers.getFirst("X-TENANT-ID") == null){
LOGGER.info(String.format("Missing X-TENANT-ID header"));
throw new ResponseStatusException(HttpStatus.UNAUTHORIZED);
}
String tenantId = headers.getFirst("X-TENANT-ID");
LOGGER.info(String.format("Processing request with tenant identifier [%s]", tenantId));
return wfc.filter(swe)
.contextWrite(TenantContextHolder.setTenantId(tenantId));
}
}
Create class to get context (credit to somewhere I found this)
public class TenantContextHolder {
public static final String TENANT_ID = TenantContextHolder.class.getName() + ".TENANT_ID";
public static Context setTenantId(String id) {
return Context.of(TENANT_ID, Mono.just(id));
}
public static Mono<String> getTenantId() {
return Mono.deferContextual(contextView -> {
if (contextView.hasKey(TENANT_ID)) {
return contextView.get(TENANT_ID);
}
return Mono.empty();
}
);
}
public static Function<Context, Context> clearContext() {
return (context) -> context.delete(TENANT_ID);
}
}
My spring security setup (all requests allowed for testing)
#EnableWebFluxSecurity
#EnableReactiveMethodSecurity
public class SecurityConfig {
#Bean
public SecurityWebFilterChain WebFilterChain(ServerHttpSecurity http) {
return http
.formLogin(it -> it.disable())
.cors(it -> it.disable()) //fix this
.httpBasic(it -> it.disable())
.csrf(it -> it.disable())
.securityContextRepository(NoOpServerSecurityContextRepository.getInstance())
.authorizeExchange(it -> it.anyExchange().permitAll()) //allow anonymous
.addFilterAt(new TenantContextFilter(), SecurityWebFiltersOrder.HTTP_BASIC)
.build();
}
}
Create Tenant Mongo DB Factory
I still have some clean-up work for defaults etc...
public class MultiTenantMongoDBFactory extends SimpleReactiveMongoDatabaseFactory {
private static final Logger LOGGER = LoggerFactory.getLogger(MultiTenantMongoDBFactory.class);
private final String defaultDb;
public MultiTenantMongoDBFactory(MongoClient mongoClient, String databaseName) {
super(mongoClient, databaseName);
this.defaultDb = databaseName;
}
#Override
public Mono<MongoDatabase> getMongoDatabase() throws DataAccessException {
return TenantContextHolder.getTenantId()
.map(id -> {
LOGGER.info(String.format("Database trying to retrieved is [%s]", id));
return super.getMongoDatabase(id);
})
.flatMap(db -> {
return db;
})
.log();
}
}
Configuration Class
#Configuration
#EnableReactiveMongoAuditing
#EnableReactiveMongoRepositories(basePackages = {"com.order.repository"})
class MongoDbConfiguration {
#Bean
public ReactiveMongoDatabaseFactory reactiveMongoDatabaseFactory() {
return new MultiTenantMongoDBFactory(MongoClients.create("mongodb://user:password#localhost:27017"), "tenant_catalog");
}
#Bean
public ReactiveMongoTemplate reactiveMongoTemplate() {
ReactiveMongoTemplate template = new ReactiveMongoTemplate(reactiveMongoDatabaseFactory());
template.setWriteResultChecking(WriteResultChecking.EXCEPTION);
return template;
}
}
Entity Class
#Document(collection = "order")
//getters
//setters
Testing
Create two mongo db's with same collection, put different documents in both
In Postman I just did a get request with the "X-TENANT-ID" header and database name as the value (e.g. tenant-12343 or tenant-34383) and good to go!
Since it's initialized in declaration, and the import implies by itself a dependency.
We have a jUnit parent test class like...
public class ServerTestBase extends TestBase {
public static final Client client = new Client();
...
And a Suite with the static import of the client and some init code in a #ClassRule using this client:
import static jwstest.test.ServerTestBase.client;
#RunWith(Suite.class)
#Suite.SuiteClasses({BunchOfSuites.class})
public class ScratchSuite {
#ClassRule
public static final ExternalResource testRule = new ExternalResource() {
#Override
protected void before() throws Throwable {
response = client.call(someService, HttpVerbs.GET).getResponse();
So, again, I don't understand, how in hell client can be null, since it's initialized on declaration, and the static import implies a dependency.
¿Any ideas? Thank you in advance.
The docs say that the field accessible in the #ClassRule has to be public static.
Static import is not such thing.
You can either extend ServerTestBase:
public class ScratchSuite extends ServerTestBase { ... }
... OR declare public static anew:
public static Client myClient = client; //from static import
I need to run inner class test cases from eclipse using Junit4. I understand that there is org.junit.runners.Enclosed that is intended to serve this purpose. It works well for "plain" unit test i.e. without the need for spring context configuration.
For my case, give sample code below, Adding another annotation of Enclosed does not work since there is a conflict of both SpringJUnit4ClassRunner and Enclosed test runners. How can I solve this problem ?
Note: Kindly ignore any basic spelling mistake/basic import issues in the below example since I tried to cook up from my actual use-case.
#RunWith(SpringJUnit4ClassRunner.class)
#ContextConfiguration(locations = { "/unit-test-context.xml"})
public class FooUnitTest {
// Mocked dependency through spring context
#Inject
protected DependentService dependentService;
public static class FooBasicScenarios extends FooUnitTest{
#Test
public void testCase1 {
.....
List<Data> data = dependentService.getData();
.....
}
}
public static class FooNeagativeScenarios extends FooUnitTest{
#Test
public void testCase1 {
.....
List<Data> data = dependentService.getData();
.....
}
}
}
}
FooUnitTest is a container, you cannot use it as a superclass.
You need to move all your spring-code to Scenario-classes. And use #RunWith(Enclosed.class). For example, with abstract superclass
#RunWith(Enclosed.class)
public class FooUnitTest {
#ContextConfiguration(locations = { "/unit-test-context.xml"})
protected abstract static class BasicTestSuit {
// Mocked dependency through spring context
#Inject
protected DependentService dependentService;
}
#RunWith(SpringJUnit4ClassRunner.class)
public static class FooBasicScenarios extends BasicTestSuit {
#Test
public void testCase1 {
.....
List<Data> data = dependentService.getData();
.....
}
}
#RunWith(SpringJUnit4ClassRunner.class)
public static class FooNeagativeScenarios extends BasicTestSuit {
#Test
public void testCase1 {
.....
List<Data> data = dependentService.getData();
.....
}
}
}
Of course you can declare all dependencies in each Scenario-class, in that case there is no necessary in abstract superclass.
I need to pass a class object through the gwt rpc connection as a generic but it seems that rpc does not cooperate with it. The class is serialized using the java.io.Serializable. I have checked it using the gwt IsSerializable but i still have the error.
Here is my code
MySource.java
#SuppressWarnings("serial")
#PersistenceCapable
#Inheritance(strategy = InheritanceStrategy.SUBCLASS_TABLE)
public abstract class MySource implements Serializable {
#PrimaryKey
#Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
private Long id;
#Persistent
private String userId;
#Persistent
private String title;
#Persistent
private String description;
#Persistent
private String blobKey;
#Persistent
private String youtubeLink;
#Persistent
private String personalLink;
#Persistent
private Date submitedDate;
#Persistent
private float price;
public float getPrice() {
return price;
}
public void setPrice(float price) {
this.price = price;
}
public String getUserId() {
return userId;
}
public void setUserId(String userId) {
this.userId = userId;
}
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
public String getBlobKey() {
return blobKey;
}
public void setBlobKey(String blobKey) {
this.blobKey = blobKey;
}
public String getYoutubeLink() {
return youtubeLink;
}
public void setYoutubeLink(String youtubeLink) {
this.youtubeLink = youtubeLink;
}
public String getPersonalLink() {
return personalLink;
}
public void setPersonalLink(String personalLink) {
this.personalLink = personalLink;
}
public Date getSubmitedDate() {
return submitedDate;
}
public void setSubmitedDate(Date submitedDate) {
this.submitedDate = submitedDate;
}
public Long getId() {
return id;
}
}
AndroidSource.java
#SuppressWarnings("serial")
#PersistenceCapable
public class AndroidSource extends MySource{
public AndroidSource() {
super();
}
}
CategoryBrowseService.java which is the remoteservice model
#RemoteServiceRelativePath("categoryService")
public interface CategoryBrowseService extends RemoteService{
ArrayList<MySource> getSourceList(Class<? extends MySource> classType);
}
CategoryBrowseServiceAsync.java
public interface CategoryBrowseServiceAsync {
void getSourceList(Class<? extends MySource> classType,
AsyncCallback<ArrayList<MySource>> callback);
}
CategoryBrowsePresenter.java where the rpc is called
private void retrieveSources(Class<? extends MySource> classType) {
CategoryBrowseServiceAsync rpcService = GWT.create(CategoryBrowseService.class);
rpcService.getSourceList(classType, new AsyncCallback<ArrayList<MySource>>() {
#Override
public void onFailure(Throwable caught) {
Window.alert("Ooops!!!Sorry!Something went wrong.I am still beta!");
}
#Override
public void onSuccess(ArrayList<MySource> result) {
sourceList = result;
display.setSourceContent(sourceList);
}
});
}
CategoryBrowseServiceImpl.java
#SuppressWarnings("serial")
public class CategoryBrowseServiceImpl extends RemoteServiceServlet implements CategoryBrowseService{
private SourceDatastore dataStore;
public CategoryBrowseServiceImpl() {
dataStore = new SourceDatastore();
}
#Override
public ArrayList<MySource> getSourceList(Class<? extends MySource> classType) {
return dataStore.getSources(classType);
}
}
Here is the error that i get.
Compiling module com.sourcebay.SourceBay
Scanning for additional dependencies: file:/home/santaris/workspace/SourceBay/src/com/sourcebay/client/presenter/mybay/browse/CategoryBrowsePresenter.java
Computing all possible rebind results for 'com.sourcebay.client.model.mybay.browse.CategoryBrowseService'
Rebinding com.sourcebay.client.model.mybay.browse.CategoryBrowseService
Invoking generator com.google.gwt.user.rebind.rpc.ServiceInterfaceProxyGenerator
Generating client proxy for remote service interface 'com.sourcebay.client.model.mybay.browse.CategoryBrowseService'
[ERROR] java.lang.Class<T> is not assignable to 'com.google.gwt.user.client.rpc.IsSerializable' or 'java.io.Serializable' nor does it have a custom field serializer (reached via java.lang.Class<? extends com.sourcebay.shared.source.MySource>)
[ERROR] java.lang.Class<T> has no available instantiable subtypes. (reached via java.lang.Class<? extends com.sourcebay.shared.source.MySource>)
[ERROR] subtype java.lang.Class<T> is not assignable to 'com.google.gwt.user.client.rpc.IsSerializable' or 'java.io.Serializable' nor does it have a custom field serializer (reached via java.lang.Class<? extends com.sourcebay.shared.source.MySource>)
[ERROR] Errors in 'file:/home/santaris/workspace/SourceBay/src/com/sourcebay/client/presenter/mybay/browse/CategoryBrowsePresenter.java'
[ERROR] Line 75: Failed to resolve 'com.sourcebay.client.model.mybay.browse.CategoryBrowseService' via deferred binding
The paradox is that when i am running my application through the eclipse plugin everything works fine. Could anyone help me please? I have checked to fix the problem through the DTO solution without any success. Moreover i have tried to implement a CustomFieldSerializer as Google suggests without any success too.
Thanks in advance,
Stefanos Antaris
P.S. Sorry for the huge post :-)
Well the problem is that you trying to transport a Class object over the network. I have no idea why it is working in dev mode (I've tried it on local project and it failed), but it shouldn't work. You have to use something else instead of Class name for example String, which will contain a name of class. Theoretically it can work if you create CustomFieldSerializer for Class, but using String instead of Class will be easier.
Classes with persistence annotations can work well on the server side, but if you want to pass its data to the client you must create a plain java serializable class to transport data from server to client.
As noted in the previous answer, persistence annotations are not supported in the client side, as they cannot be translated to equivalent javascript code (and it makes sense since the client doesn't have the responsability of persistence).
It could be that the persistence-related annotations in MySource.java make it implossible to translate to javascript. Try removing the annotations to see if it's related. Also make sure that MySource.java is in a package declared as translatable in the module xml file ("source" element).
Try using implements Serializable for defining you class.
I mean like this:
public class AndroidSource extends MySource implements Serializable{
public AndroidSource() {
super();
}
}
Your RPC Services must deal just with Serializable Objects. Domain classes are not translatable to JavaScript So GWT can't send and receive via network (RPC Protocole) such objects. You need to create DTO classes (wich shadows domain class) implementing java.io.Serializable and then reconfigure all your RPC Service to use in input DTOs and output DTOs. Good Luck for your project.
I've been through a few documentations, but am not able to communicate to the datastore yet...can anyone give me a sample project/code of objectify used in GWT web app(I use eclipse)...just a simple 'put' and 'get' action using RPC should do...or, atleast tell me how its done
Easiest way to understand how to make objectify work is to repeat all steps described in this article from David's Chandler blog. Whole blog is a pretty much must read if you interested in GWT, GAE(Java), gwt-presenter, gin\guice,etc. There you will find working example, but anyway here i'll show a slighly advanced example.
In package shared define your entity/model:
import javax.persistence.Embedded;
import javax.persistence.Id;
import com.google.gwt.user.client.rpc.IsSerializable;
import com.googlecode.objectify.Key;
import com.googlecode.objectify.annotation.Entity;
import com.googlecode.objectify.annotation.Unindexed;
#Entity
public class MyEntry implements IsSerializable {
// Objectify auto-generates Long IDs just like JDO / JPA
#Id private Long id;
#Unindexed private String text = "";
#Embedded private Time start;
// empty constructor for serialization
public MyEntry () {
}
public MyEntry (Time start, String text) {
super();
this.text = tText;
this.start = start;
}
/*constructors,getters,setters...*/
}
Time class (also shared package) contains just one field msecs:
#Entity
public class Time implements IsSerializable, Comparable<Time> {
protected int msecs = -1;
//rest of code like in MyEntry
}
Copy class ObjectifyDao from link above to your server.dao package. And then make DAO class specifically for MyEntry -- MyEntryDAO:
package com.myapp.server.dao;
import java.util.logging.Logger;
import com.googlecode.objectify.ObjectifyService;
import com.myapp.shared.MyEntryDao;
public class MyEntryDao extends ObjectifyDao<MyEntry>
{
private static final Logger LOG = Logger.getLogger(MyEntryDao.class.getName());
static
{
ObjectifyService.register(MyEntry.class);
}
public MyEntryDao()
{
super(MyEntry.class);
}
}
Finally we can make requests to database(server package):
public class FinallyDownloadingEntriesServlet extends HttpServlet {
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws
ServletException, IOException {
resp.setCharacterEncoding("UTF-8");
resp.setContentType("text/plain");
//more code...
resp.setHeader("Content-Disposition", "attachment; filename=\""+"MyFileName"+".txt\";");
try {
MyEntryDao = new MyEntryDao();
/*query to get all MyEntries from datastore sorted by start Time*/
ArrayList<MyEntry> entries = (ArrayList<MyEntry>) dao.ofy().query(MyEntry.class).order("start.msecs").list();
PrintWriter out = resp.getWriter();
int i = 0;
for (MyEntry entry : entries) {
++i;
out.println(i);
out.println(entry.getStart() + entry.getText());
out.println();
}
} finally {
//catching exceptions
}
}