Postgres and Oracle compatibility with Hibernate There are situations your JEE application needs to support Postgres and Oracle as a Database. Hibernate should do the job here, however, there are some specifics worth mentioning. While enabling Postgres for application already running Oracle I came across following tricky parts: BLOBs support, CLOBs support, Oracle not knowing Boolean type (using Integer) instead and DUAL table. These were the tricks I had to apply to make the @Entity classes running on both of these. Please note I’ve used Postgres 9.3 with Hibernate 4.2.1.SP1. BLOBs support The problem with Postgres is that it offers 2 types of BLOB storage: bytea - data stored in table oid - table holds just identifier to data stored elsewhere I guess in the most of the situations you can live with the bytea as well as I did. The other one as far as I’ve read is to be used for some huge data (in gigabytes) as it supports streams for IO operations. Well, it sounds nice there is such a support, however using Hibernate in this case can make things quite problematic (due to need to use the specific annotations), especially if you try to achieve compatibility with Oracle. To see the trouble here, see StackOverflow: proper hibernate annotation for byte[] All- the combinations are described there: annotation postgres oracle works on ------------------------------------------------------------- byte[] + @Lob oid blob oracle byte[] bytea raw(255) postgresql byte[] + @Type(PBA) oid blob oracle byte[] + @Type(BT) bytea blob postgresql where @Type(PBA) stands for: @Type(type="org.hibernate.type.PrimitiveByteArrayBlobType") and @Type(BT) stands for: @Type(type="org.hibernate.type.BinaryType"). These result in all sorts of Postgres errors, like: ERROR: column “foo” is of type oid but expression is of type bytea or ERROR: column “foo” is of type bytea but expression is of type oid Well, there seems to be a solution, still it includes patching of Hibernate library (something I see as the last option when playing with 3.rd party library). There is also a reference to official blog post from the Hibernate guys on the topic: PostgreSQL and BLOBs. Still solution described in blog post seems not working for me and based on the comments, seems to be invalid for more people. BLOBs solved OK, so now the optimistic part. After quite some debugging I ended up with the Entity definition like this : @Lob private byte[] foo; Oracle has no trouble with that, moreover I had to customize the Postgres dialect in a way: public class PostgreSQLDialectCustom extends PostgreSQL82Dialect { @Override public SqlTypeDescriptor remapSqlTypeDescriptor(SqlTypeDescriptor sqlTypeDescriptor) { if (sqlTypeDescriptor.getSqlType() == java.sql.Types.BLOB) { return BinaryTypeDescriptor.INSTANCE; } return super.remapSqlTypeDescriptor(sqlTypeDescriptor); } } That’s it! Quite simple right? That works for persisting to bytea typed columns in Postgres (as that fits my usecase). CLOBs support The errors in misconfiguration looked something like this: org.postgresql.util.PSQLException: Bad value for type long : ... So first I’ve found (on String LOBs on PostgreSQL with Hibernate 3.6) following solution: @Lob @Type(type = "org.hibernate.type.TextType") private String foo; Well, that works, but for Postgres only. Then there was a suggestion (on StackOverflow: Postgres UTF-8 clobs with JDBC) from to go for: @Lob @Type(type="org.hibernate.type.StringClobType") private String foo; That pointed me the right direction (the funny part was that it was just a comment to some answers). It was quite close, but didn’t work for me in all cases, still resulted in errors in my tests. CLOBs solved The important was @deprecation javadocs in the org.hibernate.type.StringClobType that brought me to working one: @Lob @Type(type="org.hibernate.type.MaterializedClobType") private String foo; That works for both Postgres and Oracle, without any further hacking (on Hibernate side) needed. Boolean type Oracle knows no Boolean type and the trouble is that Postgres does. As there was also some plain SQL present, I ended up In Postgres with error: ERROR: column “foo” is of type boolean but expression is of type integer I decided to enable cast from Integer to Boolean in Postgres rather than fixing all the plain SQL places (in a way found in Forum: Automatically Casting From Integer to Boolean): update pg_cast set castcontext = 'i' where oid in ( select c.oid from pg_cast c inner join pg_type src on src.oid = c.castsource inner join pg_type tgt on tgt.oid = c.casttarget where src.typname like 'int%' and tgt.typname like 'bool%'); Please note you should run the SQL update by user with provileges to update catalogs (probably not your postgres user used for DB connection from your application), as I’ve learned on Stackoverflow: Postgres - permission denied on updating pg_catalog.pg_cast. DUAL table There is one more specific in the Oracle I came across. If you have plain SQL, in Oracle there is DUAL table provied (see more info on Wikipedia on that) that might harm you in Postgres. Still the solution is simple. In Postgres create a view that would fill the similar purpose. It can be created like this: create or replace view dual as select 1; Conclusion Well that should be it. Enjoy your cross DB compatible JEE apps.

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If you need to embed and display Google Maps in your Java Desktop Swing application, then JxBrowser Java library is what you need.

Testing is a major part of our development process. After working with JUnit for some time we leaned back and thought: How can we improve our test productivity? Since we were all fond of Scala we looked at ScalaTest. We liked it from the start so we decided to go with ScalaTest for all new tests. Sure enough there were and are critics in the team who say “I just want to write my tests without having to bother with a new technology…” to convince even the last person on the team I will give you my top 5 reasons to choose ScalaTest over JUnit. 1. Multiple Comparisons Simple yet very nice is that you can do multiple comparisons for a single object. Say we have a list of books. Now we want to assure that the list contains exactly one book which is our book “Ruling the Universe”. The test code allows us to express it just like that: books should { not be empty and have size 1 and contain rulingTheUniverse } 2. Great DSLs There are many great DSLs to make the test code much shorter and nicer to read. These DSLs for Scala are much more powerful that those for Java. I will give you just two small examples for Mockito and Selenium. Mockito Sugar Say I have a book mock and I want to to check that the method publish has been called exactly once but I don’t care with which arguments. So here you go: val book = mock[Book] book expects 'publish withArgs (*) once Selenium We want to open our application in the browser check the title is “Aweseome Books” and then click on the link to explore books. With the Selenium DSL this is expressed like that: go to "http://localhost/book_app/index.html") pageTitle should be ("Awesome Books") click on linkText("Explore ...”) 3. Powerful Matchers Who needs assertions when you can have matchers? When I started out with ScalaTest I used a lot of assertions because thats what I knew. When I discovered matchers I started to use those as they are much more powerful and have a great syntax which allows you to write your test code very close to the what you actually want to express. I will give just a few examples to give you a first impression of just what you can do with matchers: Array(3,2,1) should have size 3// check the size of an array string should include regex "wo.ld"// check string against regular expression temp should be a 'file // check that temp is a file 4. Tag support JUnit has categories and ScalaTest has tags. You can tag your tests as you like and the execute only tests with certain tags or do other stuff with the tags. And that’s how you tag a test as “DbTest” and “SlowTest”: it must "save the book correctly"taggedAs(SlowTest, DbTest) in { // call to database } 5. JavaBean-style checking of object properties Say you have a book object with properties such as title and authors. Then you write a test where you want to verify the title is “Ruling the Universe” and it was published in 2012. In JUnit you write assertions like assertEquals(“Ruling the Universe”, book.getTitle()) and you need another assertion for the publication year. ScalaTest allows for JavaBean-style checking of object properties. So in ScalaTest you can declare the expected values for properties of an object. Instead of the assertions you write the property title of the book should be “Ruling the Universe” and the property publicationYear should be 2012. And thats how this looks in ScalaTest: book should have ( ‘title ("Ruling the Universe"), ‘author (List("Zaphod", "Ford")), ‘publicationYear (2012) ) Are you willing to give ScalaTest a try? You should. I like it more and more with every test I write and maybe you will too!

Sometimes we want to use Hibernate native SQL in our code. For example we might need to invoke a selectable stored procedure, we cannot invoke in another way. To invoke a native SQL query we use the method createSQLQuery() which is available from the Hibernate session object. In our Grails code we must then first get access to the current Hibernate session. Luckily we only have to inject the sessionFactory bean in our Grails service or controller. To get the current session we invoke the getCurrentSession() method and we are ready to execute a native SQL query. The query itself is defined as a String value and we can use placeholders for variables, just like with other Hibernate queries. In the following sample we create a new Grails service and use a Hibernate native SQL query to execute a selectable stored procedure with the nameorganisation_breadcrumbs. This stored procedure takes one argument startId and will return a list of results with an id, name and level column. // File: grails-app/services/com/mrhaki/grails/OrganisationService.groovy package com.mrhaki.grails import com.mrhaki.grails.Organisation class OrganisationService { // Auto inject SessionFactory we can use // to get the current Hibernate session. def sessionFactory List breadcrumbs(final Long startOrganisationId) { // Get the current Hiberante session. final session = sessionFactory.currentSession // Query string with :startId as parameter placeholder. final String query = 'select id, name, level from organisation_breadcrumbs(:startId) order by level desc' // Create native SQL query. final sqlQuery = session.createSQLQuery(query) // Use Groovy with() method to invoke multiple methods // on the sqlQuery object. final results = sqlQuery.with { // Set domain class as entity. // Properties in domain class id, name, level will // be automatically filled. addEntity(Organisation) // Set value for parameter startId. setLong('startId', startOrganisationId) // Get all results. list() } results } } In the sample code we use the addEntity() method to map the query results to the domain class Organisation. To transform the results from a query to other objects we can use the setResultTransformer() method. Hibernate (and therefore Grails if we use the Hibernate plugin) already has a set of transformers we can use. For example with the org.hibernate.transform.AliasToEntityMapResultTransformer each result row is transformed into a Map where the column aliases are the keys of the map. // File: grails-app/services/com/mrhaki/grails/OrganisationService.groovy package com.mrhaki.grails import org.hibernate.transform.AliasToEntityMapResultTransformer class OrganisationService { def sessionFactory List> breadcrumbs(final Long startOrganisationId) { final session = sessionFactory.currentSession final String query = 'select id, name, level from organisation_breadcrumbs(:startId) order by level desc' final sqlQuery = session.createSQLQuery(query) final results = sqlQuery.with { // Assign result transformer. // This transformer will map columns to keys in a map for each row. resultTransformer = AliasToEntityMapResultTransformer.INSTANCE setLong('startId', startOrganisationId) list() } results } } Finally we can execute a native SQL query and handle the raw results ourselves using the Groovy Collection API enhancements. The result of thelist() method is a List of Object[] objects. In the following sample we use Groovy syntax to handle the results: // File: grails-app/services/com/mrhaki/grails/OrganisationService.groovy package com.mrhaki.grails class OrganisationService { def sessionFactory List> breadcrumbs(final Long startOrganisationId) { final session = sessionFactory.currentSession final String query = 'select id, name, level from organisation_breadcrumbs(:startId) order by level desc' final sqlQuery = session.createSQLQuery(query) final queryResults = sqlQuery.with { setLong('startId', startOrganisationId) list() } // Transform resulting rows to a map with key organisationName. final results = queryResults.collect { resultRow -> [organisationName: resultRow[1]] } // Or to only get a list of names. //final List names = queryResults.collect { it[1] } results } } Code written with Grails 2.3.7.

Digital signing is a widely used mechanism to make digital contents authentic. By producing a digital signature for some content, we can let another party capable of validating that content. It can provide a guarantee that, is not altered after we signed it, with this validation. With this sample I am to share how to generate the a signature for SOAP envelope. But of course this is valid for any other content signing as well. Here, I will sign The SOAP envelope itself An attachment Place the signature inside SOAP header With the placement of signature inside the SOAP header which is also signed by the signature, this becomes a demonstration of enveloped signature. I am using Apache Santuario library for signing. Following is the code segment I used. I have shared the complete sample here to to be downloaded. public static void main(String unused[]) throws Exception { String keystoreType = "JKS"; String keystoreFile = "src/main/resources/PushpalankaKeystore.jks"; String keystorePass = "pushpalanka"; String privateKeyAlias = "pushpalanka"; String privateKeyPass = "pushpalanka"; String certificateAlias = "pushpalanka"; File signatureFile = new File("src/main/resources/signature.xml"); Element element = null; String BaseURI = signatureFile.toURI().toURL().toString(); //SOAP envelope to be signed File attachmentFile = new File("src/main/resources/sample.xml"); //get the private key used to sign, from the keystore KeyStore ks = KeyStore.getInstance(keystoreType); FileInputStream fis = new FileInputStream(keystoreFile); ks.load(fis, keystorePass.toCharArray()); PrivateKey privateKey = (PrivateKey) ks.getKey(privateKeyAlias, privateKeyPass.toCharArray()); //create basic structure of signature javax.xml.parsers.DocumentBuilderFactory dbf = javax.xml.parsers.DocumentBuilderFactory.newInstance(); dbf.setNamespaceAware(true); DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance(); DocumentBuilder dBuilder = dbFactory.newDocumentBuilder(); Document doc = dBuilder.parse(attachmentFile); XMLSignature sig = new XMLSignature(doc, BaseURI, XMLSignature.ALGO_ID_SIGNATURE_RSA_SHA1); //optional, but better element = doc.getDocumentElement(); element.normalize(); element.getElementsByTagName("soap:Header").item(0).appendChild(sig.getElement()); { Transforms transforms = new Transforms(doc); transforms.addTransform(Transforms.TRANSFORM_C14N_OMIT_COMMENTS); //Sign the content of SOAP Envelope sig.addDocument("", transforms, Constants.ALGO_ID_DIGEST_SHA1); //Adding the attachment to be signed sig.addDocument("../resources/attachment.xml", transforms, Constants.ALGO_ID_DIGEST_SHA1); } //Signing procedure { X509Certificate cert = (X509Certificate) ks.getCertificate(certificateAlias); sig.addKeyInfo(cert); sig.addKeyInfo(cert.getPublicKey()); sig.sign(privateKey); } //write signature to file FileOutputStream f = new FileOutputStream(signatureFile); XMLUtils.outputDOMc14nWithComments(doc, f); f.close(); } At first it reads in the private key which is to be used in signing. To create a key pair for your own, this post will be helpful. Then it has created the signature and added the SOAP message and the attachment as the documents to be signed. Finally it performs signing and write the signed document to a file. The signed SOAP message looks as follows. FUN PARTY uri:www.pjxml.org/socialService/Ping FUN PARTY FUN 59c64t0087fg3kfs000003n9 uri:www.pjxml.org/socialService/ Ping FUN 59c64t0087fg3kfs000003n9 2013-10-22T17:12:20 uri:www.pjxml.org/socialService/ Ping 9RXY9kp/Klx36gd4BULvST4qffI= 3JcccO8+0bCUUR3EJxGJKJ+Wrbc= d0hBQLIvZ4fwUZlrsDLDZojvwK2DVaznrvSoA/JTjnS7XZ5oMplN9 THX4xzZap3+WhXwI2xMr3GKO................x7u+PQz1UepcbKY3BsO8jB3dxWN6r+F4qTyWa+xwOFxqLj546WX35f8zT4GLdiJI5oiYeo1YPLFFqTrwg== MIIDjTCCAnWgAwIBAgIEeotzFjANBgkqhkiG9w0BAQsFADB3MQswCQYDVQQGEwJMSzEQMA4GA1UE...............qXfD/eY+XeIDyMQocRqTpcJIm8OneZ8vbMNQrxsRInxq+DsG+C92b k5y0amGgOQ2O/St0Kc2/xye80tX2fDEKs2YOlM/zCknL8VgK0CbAKVAwvJoycQL9mGRkPDmbitHe............StGofmsoKURzo8hofYEn41rGsq5wCuqJhhHYGDrPpFcuJiuI3SeXgcMtBnMwsIaKv2uHaPRbNX31WEuabuv6Q== AQAB 1.90 In a next post lets see how to verify this signature, so that we can guarantee signed documents are not changed. Cheers!

Java EE in general and Context and Dependency Injection has been part of the Vaadin ecosystem since ages. Recently, Spring Vaadin is a joint effort of the Vaadin and the Spring teams to bring the Spring framework into the Vaadin ecosystem, lead by Petter Holmström for Vaadin and Josh Long for Pivotal. Integration is based on the Spring Boot project - and its sub-modules, that aims to ease creating new Spring web projects. This article assumes the reader is familiar enough with Spring Boot. If not the case, please take some time to get to understand basic notions about the library. Note that at the time of this writing, there's no release for Spring Vaadin. You'll need to clone the project and build it yourself. The first step is to create the UI. In order to display usage of Spring's Dependency Injection, it should use a service dependency. Let's injection the UI through Constructor Injection to favor immutability. The only addition to a standard UI is to annotate it with org.vaadin.spring.@VaadinUI. @VaadinUI public class VaadinSpringExampleUi extends UI { private HelloService helloService; public VaadinSpringExampleUi(HelloService helloService) { this.helloService = helloService; } @Override protected void init(VaadinRequest vaadinRequest) { String hello = helloService.sayHello(); setContent(new Label(hello)); } } The second step is standard Spring Java configuration. Let's create two configuration classes, one for the main context and the other for the web one. Two thing of note: The method instantiating the previous UI has to be annotated with org.vaadin.spring.@UIScope in addition to standard Spring org.springframework.context.annotation.@Bean to bind the bean lifecycle to the new scope provided by the Spring Vaadin library. At the time of this writing, a RequestContextListener bean must be provided. In order to be compliant with future versions of the library, it's a good practice to annotate the instantiating method with @ConditionalOnMissingBean(RequestContextListener.class). @Configuration public class MainConfig { @Bean public HelloService helloService() { return new HelloService(); } } @Configuration public class WebConfig extends MainConfig { @Bean @ConditionalOnMissingBean(RequestContextListener.class) public RequestContextListener requestContextListener() { return new RequestContextListener(); } @Bean @UIScope public VaadinSpringExampleUi exampleUi() { return new VaadinSpringExampleUi(helloService()); } } The final step is to create a dedicated WebApplicationInitializer. Spring Boot already offers a concrete implementation, we just need to reference our previous configuration classes as well as those provided by Spring Vaadin, namely VaadinAutoConfiguration and VaadinConfiguration. public class ApplicationInitializer extends SpringBootServletInitializer { @Override protected SpringApplicationBuilder configure(SpringApplicationBuilder application) { return application.showBanner(false) .sources(MainConfig.class) .sources(VaadinAutoConfiguration.class, VaadinConfiguration.class) .sources(WebConfig.class); } } At this point, we demonstrated a working Spring Vaadin sample application. Code for this article can be browsed and forked on Github.

Spring Data modules provides various modules to work with various types of datasources like RDBMS, NOSQL stores etc in unified way. In my previous article SpringMVC4 + Spring Data JPA + SpringSecurity configuration using JavaConfig I have explained how to configure Spring Data JPA using JavaConfig. Now in this post let us see how we can use Spring Data JPA repositories and export JPA entities as REST endpoints using Spring Data REST. First let us configure spring-data-jpa and spring-data-rest-webmvc dependencies in our pom.xml. org.springframework.data spring-data-jpa 1.5.0.RELEASE org.springframework.data spring-data-rest-webmvc 2.0.0.RELEASE Make sure you have latest released versions configured correctly, otherwise you will encounter the following error: java.lang.ClassNotFoundException: org.springframework.data.mapping.SimplePropertyHandler Create JPA entities. @Entity @Table(name = "USERS") public class User implements Serializable { private static final long serialVersionUID = 1L; @Id @GeneratedValue(strategy = GenerationType.IDENTITY) @Column(name = "user_id") private Integer id; @Column(name = "username", nullable = false, unique = true, length = 50) private String userName; @Column(name = "password", nullable = false, length = 50) private String password; @Column(name = "firstname", nullable = false, length = 50) private String firstName; @Column(name = "lastname", length = 50) private String lastName; @Column(name = "email", nullable = false, unique = true, length = 50) private String email; @Temporal(TemporalType.DATE) private Date dob; private boolean enabled=true; @OneToMany(fetch=FetchType.EAGER, cascade=CascadeType.ALL) @JoinColumn(name="user_id") private Set roles = new HashSet<>(); @OneToMany(mappedBy = "user") private List contacts = new ArrayList<>(); //setters and getters } @Entity @Table(name = "ROLES") public class Role implements Serializable { private static final long serialVersionUID = 1L; @Id @GeneratedValue(strategy = GenerationType.IDENTITY) @Column(name = "role_id") private Integer id; @Column(name="role_name",nullable=false) private String roleName; //setters and getters } @Entity @Table(name = "CONTACTS") public class Contact implements Serializable { private static final long serialVersionUID = 1L; @Id @GeneratedValue(strategy = GenerationType.IDENTITY) @Column(name = "contact_id") private Integer id; @Column(name = "firstname", nullable = false, length = 50) private String firstName; @Column(name = "lastname", length = 50) private String lastName; @Column(name = "email", nullable = false, unique = true, length = 50) private String email; @Temporal(TemporalType.DATE) private Date dob; @ManyToOne @JoinColumn(name = "user_id") private User user; //setters and getters } Configure DispatcherServlet using AbstractAnnotationConfigDispatcherServletInitializer. Observe that we have added RepositoryRestMvcConfiguration.class to getServletConfigClasses() method. RepositoryRestMvcConfiguration is the one which does the heavy lifting of looking for Spring Data Repositories and exporting them as REST endpoints. package com.sivalabs.springdatarest.web.config; import javax.servlet.Filter; import org.springframework.data.rest.webmvc.config.RepositoryRestMvcConfiguration; import org.springframework.orm.jpa.support.OpenEntityManagerInViewFilter; import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer; import com.sivalabs.springdatarest.config.AppConfig; public class SpringWebAppInitializer extends AbstractAnnotationConfigDispatcherServletInitializer { @Override protected Class[] getRootConfigClasses() { return new Class[] { AppConfig.class}; } @Override protected Class[] getServletConfigClasses() { return new Class[] { WebMvcConfig.class, RepositoryRestMvcConfiguration.class }; } @Override protected String[] getServletMappings() { return new String[] { "/rest/*" }; } @Override protected Filter[] getServletFilters() { return new Filter[]{ new OpenEntityManagerInViewFilter() }; } } Create Spring Data JPA repositories for JPA entities. public interface UserRepository extends JpaRepository { } public interface RoleRepository extends JpaRepository { } public interface ContactRepository extends JpaRepository { } That's it. Spring Data REST will take care of rest of the things. You can use spring Rest Shell https://github.com/spring-projects/rest-shell or Chrome's Postman Addon to test the exported REST services. D:\rest-shell-1.2.1.RELEASE\bin>rest-shell http://localhost:8080:> Now we can change the baseUri using baseUri command as follows: http://localhost:8080:>baseUri http://localhost:8080/spring-data-rest-demo/rest/ http://localhost:8080/spring-data-rest-demo/rest/> http://localhost:8080/spring-data-rest-demo/rest/>list rel href ====================================================================================== users http://localhost:8080/spring-data-rest-demo/rest/users{?page,size,sort} roles http://localhost:8080/spring-data-rest-demo/rest/roles{?page,size,sort} contacts http://localhost:8080/spring-data-rest-demo/rest/contacts{?page,size,sort} Note: It seems there is an issue with rest-shell when the DispatcherServlet url mapped to "/" and issue list command it responds with "No resources found". http://localhost:8080/spring-data-rest-demo/rest/>get users/ { "_links": { "self": { "href": "http://localhost:8080/spring-data-rest-demo/rest/users/{?page,size,sort}", "templated": true }, "search": { "href": "http://localhost:8080/spring-data-rest-demo/rest/users/search" } }, "_embedded": { "users": [ { "userName": "admin", "password": "admin", "firstName": "Administrator", "lastName": null, "email": "[email protected]", "dob": null, "enabled": true, "_links": { "self": { "href": "http://localhost:8080/spring-data-rest-demo/rest/users/1" }, "roles": { "href": "http://localhost:8080/spring-data-rest-demo/rest/users/1/roles" }, "contacts": { "href": "http://localhost:8080/spring-data-rest-demo/rest/users/1/contacts" } } }, { "userName": "siva", "password": "siva", "firstName": "Siva", "lastName": null, "email": "[email protected]", "dob": null, "enabled": true, "_links": { "self": { "href": "http://localhost:8080/spring-data-rest-demo/rest/users/2" }, "roles": { "href": "http://localhost:8080/spring-data-rest-demo/rest/users/2/roles" }, "contacts": { "href": "http://localhost:8080/spring-data-rest-demo/rest/users/2/contacts" } } } ] }, "page": { "size": 20, "totalElements": 2, "totalPages": 1, "number": 0 } } You can find the source code at https://github.com/sivaprasadreddy/sivalabs-blog-samples-code/tree/master/spring-data-rest-demo For more Info on Spring Rest Shell: https://github.com/spring-projects/rest-shell

If you used earlier versions of Neo4j via its Java API with Java 6 you probably have code similar to the following to ensure write operations happen within a transaction: public class StylesOfTx { public static void main( String[] args ) throws IOException { String path = "/tmp/tx-style-test"; FileUtils.deleteRecursively(new File(path)); GraphDatabaseService db = new GraphDatabaseFactory().newEmbeddedDatabase( path ); Transaction tx = db.beginTx(); try { db.createNode(); tx.success(); } finally { tx.close(); } } } In Neo4j 2.0 Transaction started extending AutoCloseable which meant that you could use ‘try with resources’ and the ‘close’ method would be automatically called when the block finished: public class StylesOfTx { public static void main( String[] args ) throws IOException { String path = "/tmp/tx-style-test"; FileUtils.deleteRecursively(new File(path)); GraphDatabaseService db = new GraphDatabaseFactory().newEmbeddedDatabase( path ); try ( Transaction tx = db.beginTx() ) { Node node = db.createNode(); tx.success(); } } } This works quite well although it’s still possible to have transactions hanging around in an application when people don’t use this syntax – the old style is still permissible. In Venkat Subramaniam’s Java 8 book he suggests an alternative approach where we use a lambda based approach: public class StylesOfTx { public static void main( String[] args ) throws IOException { String path = "/tmp/tx-style-test"; FileUtils.deleteRecursively(new File(path)); GraphDatabaseService db = new GraphDatabaseFactory().newEmbeddedDatabase( path ); Db.withinTransaction(db, neo4jDb -> { Node node = neo4jDb.createNode(); }); } static class Db { public static void withinTransaction(GraphDatabaseService db, Consumer fn) { try ( Transaction tx = db.beginTx() ) { fn.accept(db); tx.success(); } } } } The ‘withinTransaction’ function would actually go on GraphDatabaseService or similar rather than being on that Db class but it was easier to put it on there for this example. A disadvantage of this style is that you don’t have explicit control over the transaction for handling the failure case – it’s assumed that if ‘tx.success()’ isn’t called then the transaction failed and it’s rolled back. I’m not sure what % of use cases actually need such fine grained control though. Brian Hurt refers to this as the ‘hole in the middle pattern‘ and I imagine we’ll start seeing more code of this ilk once Java 8 is released and becomes more widely used.

What is It Query by example is an alternative querying technique supported by the main JPA vendors but not by the JPA specification itself. QBE returns a result set depending on the properties that were set on an instance of the queried class. So if I create an Address entity and fill in the city field then the query will select all the Address entities having the same city field as the given Address entity. The typical use case of QBE is evaluating a search form where the user can fill in any search fields and gets the results based on the given search fields. In this case QBE can reduce code size significantly. When to Use · Using many fields of an entity in a query · User selects which fields of an Entity to use in a query · We are refactoring the entities frequently and don’t want to worry about breaking the queries that rely on them Limitations · QBE is not available in JPA 1.0 or 2.0 · Version properties, identifiers and associations are ignored · The query object should be annotated with @Entity Test Data I used the following entities to test the QBE feature of Hibernate: · Address (long id, String city, String street, String countryISO2Code, AddressType addressType) · AddressType (Integer type, String description) Imports The examples will refer to the following classes: import org.hibernate.Criteria; import org.hibernate.Session; import org.hibernate.criterion.Example; import org.hibernate.criterion.Restrictions; import org.junit.Test; import java.util.List; Utility Methods I also made two utility methods to present a list of the two entity types: private void listAddresses(List addresses) { for (Address address : addresses) { System.out.println(address.getId() + ", " + address.getCountryISO2Code() + ", " + address.getCity() + ", " + address.getStreet() + ", " + address.getAddressType().getType() + ", " + address.getAddressType().getDescription()); } } private void listAddressTypes(List addressTypes) { for (AddressType addressType : addressTypes) { System.out.println(addressType.getType() + ", " + addressType.getDescription()); } } Example 1: Equals This example code returns the Address entities matching the given CountryISO2Code and City. Method: @Test public void testEquals() throws Exception { Session session = (Session) entityManager.getDelegate(); Address address = new Address(); address.setCountryISO2Code("US"); address.setCity("CHICAGO"); Example addressExample = Example.create(address); Criteria criteria = session.createCriteria(Address.class).add(addressExample); listAddresses(criteria.list()); } Result: 75, US, CHICAGO, Los Angeles Way2, 6, Customer 170, US, CHICAGO, Jackson Blvd 33a, 4, Delivery 63, US, CHICAGO, Main Avenue 1, 5, Bill to 37, US, CHICAGO, Jackson Blvd 33a, 4, Delivery 36, US, CHICAGO, Jackson Blvd 33a, 4, Delivery Example 2: Id Limitation This example presents that id fields in the query object are ignored. Method: @Test public void testIdLimitation() throws Exception { Session session = (Session) entityManager.getDelegate(); Address address = new Address(); address.setCountryISO2Code("US"); address.setCity("CHICAGO"); address.setId(100); // setting id is ignored Example addressExample = Example.create(address); Criteria criteria = session.createCriteria(Address.class).add(addressExample); listAddresses(criteria.list()); } Result: 75, US, CHICAGO, Los Angeles Way2, 6, Customer 170, US, CHICAGO, Jackson Blvd 33a, 4, Delivery 63, US, CHICAGO, Main Avenue 1, 5, Bill to 37, US, CHICAGO, Jackson Blvd 33a, 4, Delivery 36, US, CHICAGO, Jackson Blvd 33a, 4, Delivery Example 3: Association Limitation Associations of the query object are ignored, too. Method: @Test public void testAssociationLimitation() throws Exception { Session session = (Session) entityManager.getDelegate(); Address address = new Address(); address.setCountryISO2Code("US"); address.setCity("CHICAGO"); AddressType addressType = new AddressType(); addressType.setType(5); address.setAddressType(addressType); // setting an association is ignored Example addressExample = Example.create(address); Criteria criteria = session.createCriteria(Address.class).add(addressExample); listAddresses(criteria.list()); } Result: 75, US, CHICAGO, Los Angeles Way2, 6, Customer 170, US, CHICAGO, Jackson Blvd 33a, 4, Delivery 63, US, CHICAGO, Main Avenue 1, 5, Bill to 37, US, CHICAGO, Jackson Blvd 33a, 4, Delivery 36, US, CHICAGO, Jackson Blvd 33a, 4, Delivery Example 4: Like QBE supports like in the query object if we enable it with Example.enableLike(). Method: @Test public void testLike() throws Exception { Session session = (Session) entityManager.getDelegate(); Address address = new Address(); address.setCountryISO2Code("US"); address.setCity("AT%"); Example addressExample = Example.create(address).enableLike(); Criteria criteria = session.createCriteria(Address.class).add(addressExample); listAddresses(criteria.list()); } Result: 83, US, ATLANTA, null, 6, Customer 184, US, ATLANTA, null, 1, Shipper 25, US, ATLANTA, null, 1, Shipper Example 5: ExcludeProperty We can exclude a property with Example.excludeProperty(String propertyName). Method: @Test public void testExcludeProperty() throws Exception { Session session = (Session) entityManager.getDelegate(); Address address = new Address(); address.setCountryISO2Code("US"); address.setCity("AT%"); Example addressExample = Example.create(address).enableLike() .excludeProperty("countryISO2Code"); // countryISO2Code is a property of Address Criteria criteria = session.createCriteria(Address.class).add(addressExample); listAddresses(criteria.list()); } Result: 154, GR, ATHENS, BETA ALPHA Street 5, 2, Consignee 83, US, ATLANTA, null, 6, Customer 25, US, ATLANTA, null, 1, Shipper 184, US, ATLANTA, null, 1, Shipper Example 6: IgnoreCase Case-insensitive search is supported by Example.ignoreCase(). Method: @Test public void testIgnoreCase() throws Exception { Session session = (Session) entityManager.getDelegate(); AddressType addressType = new AddressType(); addressType.setDescription("customer"); Example addressTypeExample = Example.create(addressType).ignoreCase(); Criteria criteria = session.createCriteria(AddressType.class) .add(addressTypeExample); listAddressTypes(criteria.list()); } Result: 6, Customer Example 7: ExcludeZeroes We can ignore 0 values of the query object by Example.excludeZeroes(). Method: @Test public void testExcludeZeroes() throws Exception { Session session = (Session) entityManager.getDelegate(); AddressType addressType = new AddressType(); addressType.setType(0); addressType.setDescription("Customer"); Example addressTypeExample = Example.create(addressType) .excludeZeroes(); Criteria criteria = session.createCriteria(AddressType.class) .add(addressTypeExample); listAddressTypes(criteria.list()); } Result: 6, Customer Example 8: Combining with Criteria QBE can be combined with criteria query. In this example we add further restriction to the query object using criteria query. Method: @Test public void testCombiningWithCriteria() throws Exception { Session session = (Session) entityManager.getDelegate(); AddressType addressType = new AddressType(); addressType.setDescription("Customer"); Example addressTypeExample = Example.create(addressType); Criteria criteria = session .createCriteria(AddressType.class).add(addressTypeExample) .add(Restrictions.eq("type", 6)); listAddressTypes(criteria.list()); } Result: 6, Customer Example 9: Association With criteria query we can filter both sides of an association, using two query objects. Method: @Test public void testAssociation() throws Exception { Session session = (Session) entityManager.getDelegate(); Address address = new Address(); address.setCountryISO2Code("US"); AddressType addressType = new AddressType(); addressType.setType(6); Example addressExample = Example.create(address); Example addressTypeExample = Example.create(addressType); Criteria criteria = session.createCriteria(Address.class).add(addressExample) .createCriteria("addressType").add(addressTypeExample); // addressType is a property of Address listAddresses(criteria.list()); } Result: 84, US, BOSTON, null, 6, Customer 83, US, ATLANTA, null, 6, Customer 82, US, SAN FRANCISCO, null, 6, Customer 75, US, CHICAGO, Los Angeles Way2, 6, Customer EclipseLink EclipseLink QBE uses QueryByExamplePolicy, ReadObjectQuery and JpaHelper: QueryByExamplePolicy qbePolicy =newQueryByExamplePolicy(); qbePolicy.excludeDefaultPrimitiveValues(); Address address =newAddress(); address.setCity("CHICAGO"); ReadObjectQuery roq =newReadObjectQuery(address, qbePolicy); Query query =JpaHelper.createQuery(roq, entityManager); OpenJPA OpenJPA uses OpenJPAQueryBuilder: CriteriaQuery cq = openJPAQueryBuilder.createQuery(Address.class); Address address =newAddress(); address.setCity("CHICAGO"); cq.where(openJPAQueryBuilder.qbe(cq.from(Address.class), address); References Hibernate: · Srinivas Guruzu and Gary Mak: Hibernate Recipes: A Problem-Solution Approach (Apress) · http://docs.jboss.org/hibernate/core/3.3/reference/en/html/querycriteria.html#querycriteria-examples · http://www.java2s.com/Code/Java/Hibernate/CriteriaQBEQueryByExampleCriteria.htm · http://www.dzone.com/snippets/hibernate-query-example · http://gal-levinsky.blogspot.de/2012/01/qbe-pattern.html Hibernate associations: · http://stackoverflow.com/questions/9309884/query-by-example-on-associations · http://stackoverflow.com/questions/8236596/hibernate-query-by-example-equivalent-of-association-criteria-query JPA: · http://stackoverflow.com/questions/2880209/jpa-findbyexample EclipseLink: · http://www.coderanch.com/t/486528/ORM/databases/findByExample-JPA-book OpenJPA: · http://www.ibm.com/developerworks/java/library/j-typesafejpa/#N10C18

Within this post we will have a deeper look into the new Date/Time API we get with Java 8 (JSR 310). Please note that this post is mainly driven by code examples that show the new API functionality. I think the examples are self-explanatory so I did not spent much time writing text around them :-) Let's get started! Working with Date and Time Objects All classes of the Java 8 Date/Time API are located within the java.time package. The first class we want to look at is java.time.LocalDate. A LocalDate represents a year-month-day date without time. We start with creating new LocalDate instances: // the current date LocalDate currentDate = LocalDate.now(); // 2014-02-10 LocalDate tenthFeb2014 = LocalDate.of(2014, Month.FEBRUARY, 10); // months values start at 1 (2014-08-01) LocalDate firstAug2014 = LocalDate.of(2014, 8, 1); // the 65th day of 2010 (2010-03-06) LocalDate sixtyFifthDayOf2010 = LocalDate.ofYearDay(2010, 65); LocalTime and LocalDateTime are the next classes we look at. Both work similar to LocalDate. ALocalTime works with time (without dates) while LocalDateTime combines date and time in one class: LocalTime currentTime = LocalTime.now(); // current time LocalTime midday = LocalTime.of(12, 0); // 12:00 LocalTime afterMidday = LocalTime.of(13, 30, 15); // 13:30:15 // 12345th second of day (03:25:45) LocalTime fromSecondsOfDay = LocalTime.ofSecondOfDay(12345); // dates with times, e.g. 2014-02-18 19:08:37.950 LocalDateTime currentDateTime = LocalDateTime.now(); // 2014-10-02 12:30 LocalDateTime secondAug2014 = LocalDateTime.of(2014, 10, 2, 12, 30); // 2014-12-24 12:00 LocalDateTime christmas2014 = LocalDateTime.of(2014, Month.DECEMBER, 24, 12, 0); By default LocalDate/Time classes will use the system clock in the default time zone. We can change this by providing a time zone or an alternative Clock implementation: // current (local) time in Los Angeles LocalTime currentTimeInLosAngeles = LocalTime.now(ZoneId.of("America/Los_Angeles")); // current time in UTC time zone LocalTime nowInUtc = LocalTime.now(Clock.systemUTC()); From LocalDate/Time objects we can get all sorts of useful information we might need. Some examples: LocalDate date = LocalDate.of(2014, 2, 15); // 2014-06-15 boolean isBefore = LocalDate.now().isBefore(date); // false // information about the month Month february = date.getMonth(); // FEBRUARY int februaryIntValue = february.getValue(); // 2 int minLength = february.minLength(); // 28 int maxLength = february.maxLength(); // 29 Month firstMonthOfQuarter = february.firstMonthOfQuarter(); // JANUARY // information about the year int year = date.getYear(); // 2014 int dayOfYear = date.getDayOfYear(); // 46 int lengthOfYear = date.lengthOfYear(); // 365 boolean isLeapYear = date.isLeapYear(); // false DayOfWeek dayOfWeek = date.getDayOfWeek(); int dayOfWeekIntValue = dayOfWeek.getValue(); // 6 String dayOfWeekName = dayOfWeek.name(); // SATURDAY int dayOfMonth = date.getDayOfMonth(); // 15 LocalDateTime startOfDay = date.atStartOfDay(); // 2014-02-15 00:00 // time information LocalTime time = LocalTime.of(15, 30); // 15:30:00 int hour = time.getHour(); // 15 int second = time.getSecond(); // 0 int minute = time.getMinute(); // 30 int secondOfDay = time.toSecondOfDay(); // 55800 Some information can be obtained without providing a specific date. For example, we can use the Year class if we need information about a specific year: Year currentYear = Year.now(); Year twoThousand = Year.of(2000); boolean isLeap = currentYear.isLeap(); // false int length = currentYear.length(); // 365 // sixtyFourth day of 2014 (2014-03-05) LocalDate date = Year.of(2014).atDay(64); We can use the plus and minus methods to add or subtract specific amounts of time. Note that these methods always return a new instance (Java 8 date/time classes are immutable). LocalDate tomorrow = LocalDate.now().plusDays(1); // before 5 houres and 30 minutes LocalDateTime dateTime = LocalDateTime.now().minusHours(5).minusMinutes(30); TemporalAdjusters are another nice way for date manipulation. TemporalAdjuster is a single method interface that is used to separate the process of adjustment from actual date/time objects. A set of common TemporalAdjusters can be accessed using static methods of the TemporalAdjusters class. LocalDate date = LocalDate.of(2014, Month.FEBRUARY, 25); // 2014-02-25 // first day of february 2014 (2014-02-01) LocalDate firstDayOfMonth = date.with(TemporalAdjusters.firstDayOfMonth()); // last day of february 2014 (2014-02-28) LocalDate lastDayOfMonth = date.with(TemporalAdjusters.lastDayOfMonth()); Static imports make this more fluent to read: import static java.time.temporal.TemporalAdjusters.*; ... // last day of 2014 (2014-12-31) LocalDate lastDayOfYear = date.with(lastDayOfYear()); // first day of next month (2014-03-01) LocalDate firstDayOfNextMonth = date.with(firstDayOfNextMonth()); // next sunday (2014-03-02) LocalDate nextSunday = date.with(next(DayOfWeek.SUNDAY)); Time Zones Working with time zones is another big topic that is simplified by the new API. The LocalDate/Time classes we have seen so far do not contain information about a time zone. If we want to work with a date/time in a certain time zone we can use ZonedDateTime or OffsetDateTime: ZoneId losAngeles = ZoneId.of("America/Los_Angeles"); ZoneId berlin = ZoneId.of("Europe/Berlin"); // 2014-02-20 12:00 LocalDateTime dateTime = LocalDateTime.of(2014, 02, 20, 12, 0); // 2014-02-20 12:00, Europe/Berlin (+01:00) ZonedDateTime berlinDateTime = ZonedDateTime.of(dateTime, berlin); // 2014-02-20 03:00, America/Los_Angeles (-08:00) ZonedDateTime losAngelesDateTime = berlinDateTime.withZoneSameInstant(losAngeles); int offsetInSeconds = losAngelesDateTime.getOffset().getTotalSeconds(); // -28800 // a collection of all available zones Set allZoneIds = ZoneId.getAvailableZoneIds(); // using offsets LocalDateTime date = LocalDateTime.of(2013, Month.JULY, 20, 3, 30); ZoneOffset offset = ZoneOffset.of("+05:00"); // 2013-07-20 03:30 +05:00 OffsetDateTime plusFive = OffsetDateTime.of(date, offset); // 2013-07-19 20:30 -02:00 OffsetDateTime minusTwo = plusFive.withOffsetSameInstant(ZoneOffset.ofHours(-2)); Timestamps Classes like LocalDate and ZonedDateTime provide a human view on time. However, often we need to work with time viewed from a machine perspective. For this we can use the Instant class which represents timestamps. An Instant counts the time beginning from the first second of January 1, 1970 (1970-01-01 00:00:00) also called the EPOCH. Instant values can be negative if they occured before the epoch. They followISO 8601 the standard for representing date and time. // current time Instant now = Instant.now(); // from unix timestamp, 2010-01-01 12:00:00 Instant fromUnixTimestamp = Instant.ofEpochSecond(1262347200); // same time in millis Instant fromEpochMilli = Instant.ofEpochMilli(1262347200000l); // parsing from ISO 8601 Instant fromIso8601 = Instant.parse("2010-01-01T12:00:00Z"); // toString() returns ISO 8601 format, e.g. 2014-02-15T01:02:03Z String toIso8601 = now.toString(); // as unix timestamp long toUnixTimestamp = now.getEpochSecond(); // in millis long toEpochMillis = now.toEpochMilli(); // plus/minus methods are available too Instant nowPlusTenSeconds = now.plusSeconds(10); Periods and Durations Period and Duration are two other important classes. Like the names suggest they represent a quantity or amount of time. A Period uses date based values (years, months, days) while a Duration uses seconds or nanoseconds to define an amount of time. Duration is most suitable when working with Instants and machine time. Periods and Durations can contain negative values if the end point occurs before the starting point. // periods LocalDate firstDate = LocalDate.of(2010, 5, 17); // 2010-05-17 LocalDate secondDate = LocalDate.of(2015, 3, 7); // 2015-03-07 Period period = Period.between(firstDate, secondDate); int days = period.getDays(); // 18 int months = period.getMonths(); // 9 int years = period.getYears(); // 4 boolean isNegative = period.isNegative(); // false Period twoMonthsAndFiveDays = Period.ofMonths(2).plusDays(5); LocalDate sixthOfJanuary = LocalDate.of(2014, 1, 6); // add two months and five days to 2014-01-06, result is 2014-03-11 LocalDate eleventhOfMarch = sixthOfJanuary.plus(twoMonthsAndFiveDays); // durations Instant firstInstant= Instant.ofEpochSecond( 1294881180 ); // 2011-01-13 01:13 Instant secondInstant = Instant.ofEpochSecond(1294708260); // 2011-01-11 01:11 Duration between = Duration.between(firstInstant, secondInstant); // negative because firstInstant is after secondInstant (-172920) long seconds = between.getSeconds(); // get absolute result in minutes (2882) long absoluteResult = between.abs().toMinutes(); // two hours in seconds (7200) long twoHoursInSeconds = Duration.ofHours(2).getSeconds(); Formatting and Parsing Formatting and parsing is another big topic when working with dates and times. In Java 8 this can be accomplished by using the format() and parse() methods: // 2014-04-01 10:45 LocalDateTime dateTime = LocalDateTime.of(2014, Month.APRIL, 1, 10, 45); // format as basic ISO date format (20140220) String asBasicIsoDate = dateTime.format(DateTimeFormatter.BASIC_ISO_DATE); // format as ISO week date (2014-W08-4) String asIsoWeekDate = dateTime.format(DateTimeFormatter.ISO_WEEK_DATE); // format ISO date time (2014-02-20T20:04:05.867) String asIsoDateTime = dateTime.format(DateTimeFormatter.ISO_DATE_TIME); // using a custom pattern (01/04/2014) String asCustomPattern = dateTime.format(DateTimeFormatter.ofPattern("dd/MM/yyyy")); // french date formatting (1. avril 2014) String frenchDate = dateTime.format(DateTimeFormatter.ofPattern("d. MMMM yyyy", new Locale("fr"))); // using short german date/time formatting (01.04.14 10:45) DateTimeFormatter formatter = DateTimeFormatter.ofLocalizedDateTime(FormatStyle.SHORT) .withLocale(new Locale("de")); String germanDateTime = dateTime.format(formatter); // parsing date strings LocalDate fromIsoDate = LocalDate.parse("2014-01-20"); LocalDate fromIsoWeekDate = LocalDate.parse("2014-W14-2", DateTimeFormatter.ISO_WEEK_DATE); LocalDate fromCustomPattern = LocalDate.parse("20.01.2014", DateTimeFormatter.ofPattern("dd.MM.yyyy")); Conversion Of course we do not always have objects of the type we need. Therefore, we need an option to convert different date/time related objects between each other. The following examples show some of the possible conversion options: // LocalDate/LocalTime <-> LocalDateTime LocalDate date = LocalDate.now(); LocalTime time = LocalTime.now(); LocalDateTime dateTimeFromDateAndTime = LocalDateTime.of(date, time); LocalDate dateFromDateTime = LocalDateTime.now().toLocalDate(); LocalTime timeFromDateTime = LocalDateTime.now().toLocalTime(); // Instant <-> LocalDateTime Instant instant = Instant.now(); LocalDateTime dateTimeFromInstant = LocalDateTime.ofInstant(instant, ZoneId.of("America/Los_Angeles")); Instant instantFromDateTime = LocalDateTime.now().toInstant(ZoneOffset.ofHours(-2)); // convert old date/calendar/timezone classes Instant instantFromDate = new Date().toInstant(); Instant instantFromCalendar = Calendar.getInstance().toInstant(); ZoneId zoneId = TimeZone.getDefault().toZoneId(); ZonedDateTime zonedDateTimeFromGregorianCalendar = new GregorianCalendar().toZonedDateTime(); // convert to old classes Date dateFromInstant = Date.from(Instant.now()); TimeZone timeZone = TimeZone.getTimeZone(ZoneId.of("America/Los_Angeles")); GregorianCalendar gregorianCalendar = GregorianCalendar.from(ZonedDateTime.now()); Conclusion With Java 8 we get a very rich API for working with date and time located in the java.time package. The API can completely replace old classes like java.util.Date or java.util.Calendar with newer, more flexible classes. Due to mostly immutable classes the new API helps in building thread safe systems. The source of the examples can be found on GitHub.

We all write unit tests but the challenge we face at times is that the unit under test might be dependent on other components. And configuring other components for unit testing is definitely an overkill. Instead we can make use of Mocks in place of the other components and continue with the unit testing. To show how one can use mocks, I have a Data access layer(DAL), basically a class which provides an API for the application to access and modify the data in the data repository. I then unit test the DAL without actually the need to connect to the data repository. The data repository can be a local database or remote database or a file system or any place where we can store and retrieve the data. The use of a DAL class helps us in keeping the data mappers separate from the application code. Lets create a Java project using maven. mvn archetype:generate -DgroupId=info.sanaulla -DartifactId=MockitoDemo -DarchetypeArtifactId=maven-archetype-quickstart -DinteractiveMode=false The above creates a folder MockitoDemo and then creates the entire directory structure for source and test files. Consider the below model class for this example: package info.sanaulla.models; import java.util.List; /** * Model class for the book details. */ public class Book { private String isbn; private String title; private List authors; private String publication; private Integer yearOfPublication; private Integer numberOfPages; private String image; public Book(String isbn, String title, List authors, String publication, Integer yearOfPublication, Integer numberOfPages, String image){ this.isbn = isbn; this.title = title; this.authors = authors; this.publication = publication; this.yearOfPublication = yearOfPublication; this.numberOfPages = numberOfPages; this.image = image; } public String getIsbn() { return isbn; } public String getTitle() { return title; } public List getAuthors() { return authors; } public String getPublication() { return publication; } public Integer getYearOfPublication() { return yearOfPublication; } public Integer getNumberOfPages() { return numberOfPages; } public String getImage() { return image; } } The DAL class for operating on the Book model class is: package info.sanaulla.dal; import info.sanaulla.models.Book; import java.util.ArrayList; import java.util.Arrays; import java.util.Collections; import java.util.List; /** * API layer for persisting and retrieving the Book objects. */ public class BookDAL { private static BookDAL bookDAL = new BookDAL(); public List getAllBooks(){ return Collections.EMPTY_LIST; } public Book getBook(String isbn){ return null; } public String addBook(Book book){ return book.getIsbn(); } public String updateBook(Book book){ return book.getIsbn(); } public static BookDAL getInstance(){ return bookDAL; } } The DAL layer above currently has no functionality and we are going to unit test that piece of code (TDD). The DAL layer might communicate with a ORM Mapper or Database API which we are not concerned while designing the API. Test Driving the DAL Layer There are lot of frameworks for Unit testing and mocking in Java but for this example I would be picking JUnit for unit testing and Mockito for mocking. We would have to update the dependency in Maven’s pom.xml 4.0.0 info.sanaulla MockitoDemo jar 1.0-SNAPSHOT MockitoDemo http://maven.apache.org junit junit 4.10 test org.mockito mockito-all 1.9.5 test Now lets unit test the BookDAL. During the unit testing we will inject mock data into the BookDAL so that we can complete the testing of the API without depending on the data source. Initially we will have an empty test class: public class BookDALTest { public void setUp() throws Exception { } public void testGetAllBooks() throws Exception { } public void testGetBook() throws Exception { } public void testAddBook() throws Exception { } public void testUpdateBook() throws Exception { } } We will inject the mock BookDAL and mock data in the setUp() as shown below: public class BookDALTest { private static BookDAL mockedBookDAL; private static Book book1; private static Book book2; @BeforeClass public static void setUp(){ //Create mock object of BookDAL mockedBookDAL = mock(BookDAL.class); //Create few instances of Book class. book1 = new Book("8131721019","Compilers Principles", Arrays.asList("D. Jeffrey Ulman","Ravi Sethi", "Alfred V. Aho", "Monica S. Lam"), "Pearson Education Singapore Pte Ltd", 2008,1009,"BOOK_IMAGE"); book2 = new Book("9788183331630","Let Us C 13th Edition", Arrays.asList("Yashavant Kanetkar"),"BPB PUBLICATIONS", 2012,675,"BOOK_IMAGE"); //Stubbing the methods of mocked BookDAL with mocked data. when(mockedBookDAL.getAllBooks()).thenReturn(Arrays.asList(book1, book2)); when(mockedBookDAL.getBook("8131721019")).thenReturn(book1); when(mockedBookDAL.addBook(book1)).thenReturn(book1.getIsbn()); when(mockedBookDAL.updateBook(book1)).thenReturn(book1.getIsbn()); } public void testGetAllBooks() throws Exception {} public void testGetBook() throws Exception {} public void testAddBook() throws Exception {} public void testUpdateBook() throws Exception {} } In the above setUp() method I have: Created a mock object of BookDAL BookDAL mockedBookDAL = mock(BookDAL.class); Stubbed the API of BookDAL with mock data, such that when ever the API is invoked the mocked data is returned. //When getAllBooks() is invoked then return the given data and so on for the other methods. when(mockedBookDAL.getAllBooks()).thenReturn(Arrays.asList(book1, book2)); when(mockedBookDAL.getBook("8131721019")).thenReturn(book1); when(mockedBookDAL.addBook(book1)).thenReturn(book1.getIsbn()); when(mockedBookDAL.updateBook(book1)).thenReturn(book1.getIsbn()); Populating the rest of the tests we get: package info.sanaulla.dal; import info.sanaulla.models.Book; import org.junit.BeforeClass; import org.junit.Test; import static org.junit.Assert.*; import static org.mockito.Mockito.mock; import static org.mockito.Mockito.when; import java.util.Arrays; import java.util.List; public class BookDALTest { private static BookDAL mockedBookDAL; private static Book book1; private static Book book2; @BeforeClass public static void setUp(){ mockedBookDAL = mock(BookDAL.class); book1 = new Book("8131721019","Compilers Principles", Arrays.asList("D. Jeffrey Ulman","Ravi Sethi", "Alfred V. Aho", "Monica S. Lam"), "Pearson Education Singapore Pte Ltd", 2008,1009,"BOOK_IMAGE"); book2 = new Book("9788183331630","Let Us C 13th Edition", Arrays.asList("Yashavant Kanetkar"),"BPB PUBLICATIONS", 2012,675,"BOOK_IMAGE"); when(mockedBookDAL.getAllBooks()).thenReturn(Arrays.asList(book1, book2)); when(mockedBookDAL.getBook("8131721019")).thenReturn(book1); when(mockedBookDAL.addBook(book1)).thenReturn(book1.getIsbn()); when(mockedBookDAL.updateBook(book1)).thenReturn(book1.getIsbn()); } @Test public void testGetAllBooks() throws Exception { List allBooks = mockedBookDAL.getAllBooks(); assertEquals(2, allBooks.size()); Book myBook = allBooks.get(0); assertEquals("8131721019", myBook.getIsbn()); assertEquals("Compilers Principles", myBook.getTitle()); assertEquals(4, myBook.getAuthors().size()); assertEquals((Integer)2008, myBook.getYearOfPublication()); assertEquals((Integer) 1009, myBook.getNumberOfPages()); assertEquals("Pearson Education Singapore Pte Ltd", myBook.getPublication()); assertEquals("BOOK_IMAGE", myBook.getImage()); } @Test public void testGetBook(){ String isbn = "8131721019"; Book myBook = mockedBookDAL.getBook(isbn); assertNotNull(myBook); assertEquals(isbn, myBook.getIsbn()); assertEquals("Compilers Principles", myBook.getTitle()); assertEquals(4, myBook.getAuthors().size()); assertEquals("Pearson Education Singapore Pte Ltd", myBook.getPublication()); assertEquals((Integer)2008, myBook.getYearOfPublication()); assertEquals((Integer)1009, myBook.getNumberOfPages()); } @Test public void testAddBook(){ String isbn = mockedBookDAL.addBook(book1); assertNotNull(isbn); assertEquals(book1.getIsbn(), isbn); } @Test public void testUpdateBook(){ String isbn = mockedBookDAL.updateBook(book1); assertNotNull(isbn); assertEquals(book1.getIsbn(), isbn); } } One can run the test by using maven command: mvn test. The output is: ------------------------------------------------------- T E S T S ------------------------------------------------------- Running info.sanaulla.AppTest Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.029 sec Running info.sanaulla.dal.BookDALTest Tests run: 4, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.209 sec Results : Tests run: 5, Failures: 0, Errors: 0, Skipped: 0 So we have been able to test the DAL class without actually configuring the data source by using mocks.

The WebLogic Server 12c has very nice support for Maven now. The doc for this is kinda hidden though, so here is a direct link http://docs.oracle.com/middleware/1212/core/MAVEN To summarize the doc, Oracle did not provide a public Maven repository manager hosting for their server artifacts. However they do now provide a tool for you to create and populate your own. You can setup either your local repository (if you are working mostly on your own in a single computer), or you may deploy them into your own internal Maven repository manager such as Archiva or Nexus. Here I would show how the local repository is done. First step is use a maven plugin provided by WLS to populate the repository. I am using a MacOSX for this demo and my WLS is installed in $HOME/apps/wls12120. If you are on Windows, you may install it under C:/apps/wls12120. $ cd $HOME/apps/wls12120/oracle_common/plugins/maven/com/oracle/maven/oracle-maven-sync/12.1.2/ $ mvn install:install-file -DpomFile=oracle-maven-sync.12.1.2.pom -Dfile=oracle-maven-sync.12.1.2.jar $ mvn com.oracle.maven:oracle-maven-sync:push -Doracle-maven-sync.oracleHome=$HOME/apps/wls12120 -Doracle-maven-sync.testingOnly=false The artifacts are placed under your local $HOME/.m2/repository/com/oracle. Now you may use Maven to build Java EE application with these WebLogic artifact as dependencies. Not only these are available, the push also populated some additional maven plugins that helps development more easy. For example, you can generate a template project using their archetype plugin. $ cd $HOME $ mvn archetype:generate \ -DarchetypeGroupId=com.oracle.weblogic.archetype \ -DarchetypeArtifactId=basic-webapp \ -DarchetypeVersion=12.1.2-0-0 \ -DgroupId=org.mycompany \ -DartifactId=my-basic-webapp-project \ -Dversion=1.0-SNAPSHOT Type 'Y' to confirm to finish. Notice that pom.xml it generated; it is using the "javax:javaee-web-api:6.0:provided" dependency. This is working because we setup the repository earlier. Now you may build it. $ cd my-basic-webapp-project $ mvn package After this build you should have the war file under the target directory.You may manually copy and deploy this into your WebLogic server domain. Or you may continue to configure the maven pom to do this all with maven. Here is how I do it. Edit the my-basic-webapp-project/pom.xml file and replace the weblogic-maven-plugin plugin like this: com.oracle.weblogic weblogic-maven-plugin 12.1.2-0-0 ${oracleMiddlewareHome} ${oracleServerUrl} ${oracleUsername} ${oraclePassword} ${project.build.directory}/${project.build.finalName}.${project.packaging} ${oracleServerName} true ${project.build.finalName} With this change, you may deploy the webapp into WebLogic server (well, assuming you already started your "mydomain" with "myserver" server running locally. See my previous blog for instructions) $ cd my-basic-webapp-project $ mvn weblogic:deploy -DoracleMiddlewareHome=$HOME/apps/wls12120 -DoracleServerName=myserver -DoracleUsername=admin -DoraclePassword=admin123 After the "BUILD SUCCESS" message, you may visit the http://localhost:7001/basicWebapp URL. Revisit the WLS doc again and you will find that they also provide other project templates (Maven calls these archetypes) for building EJB, MDB, or WebService projects. These should help you get your EE projects started quickly.

This article deals with different approaches to load multiple versions of the same class. The problem: Many times during the development you will need to work with different libraries versions which not always backward compatible or from some reason you need to support multiple versions of the same library. Using standard Java classloaders will not solve this issue since they all use "loadClass" method to load a specific class only once. After that "loadClass" will return the reference of the existing Class instance. The solution: Using another classloader to load the library (or multiple classloaders). There are several approaches available to achieve that: Use a URLClassLoader: This class loader will allow you to load your jars via URLs, or specify a directory for your classes location. Here is an example: URLClassLoader clsLoader = URLClassLoader.newInstance(new URL[] {new URL("file:/C://Test/test.jar")}); Class cls = clsLoader.loadClass("test.Main"); Method method = cls.getMethod("main", String[].class); String[]params = new String[2]; method.invoke(null, (Object) params); 2. Write your own custom class loader. Since Java class loaders (including URLClassLoader) first ask to load classes from their parent class loader, you can encounter a situation where you will need your custom classloader to load the classes from your specified location first. In this case here is a sample of a custom class loader which do exactly that: import java.net.URL; import java.net.URLClassLoader; import java.util.List; public class CustomClassLoader extends ClassLoader { private ChildClassLoader childClassLoader; public CustomClassLoader(List classpath) { super(Thread.currentThread().getContextClassLoader()); URL[] urls = classpath.toArray(new URL[classpath.size()]); childClassLoader = new ChildClassLoader( urls, new DetectClass(this.getParent()) ); } @Override protected synchronized Class loadClass(String name, boolean resolve) throws ClassNotFoundException { try { return childClassLoader.findClass(name); } catch( ClassNotFoundException e ) { return super.loadClass(name, resolve); } } private static class ChildClassLoader extends URLClassLoader { private DetectClass realParent; public ChildClassLoader( URL[] urls, DetectClass realParent ) { super(urls, null); this.realParent = realParent; } @Override public Class findClass(String name) throws ClassNotFoundException { try { Class loaded = super.findLoadedClass(name); if( loaded != null ) return loaded; return super.findClass(name); } catch( ClassNotFoundException e ) { return realParent.loadClass(name); } } } private static class DetectClass extends ClassLoader { public DetectClass(ClassLoader parent) { super(parent); } @Override public Class findClass(String name) throws ClassNotFoundException { return super.findClass(name); } } }

Java is a minimalist language with deliberately less features than other languages, never the less it has edge cases which strange effects, and even some common cases with surprising effects to trip up the unwary. If you are used to reading another language you can easily read Java the wrong way leaving to confusion. Variables are only references or primitives That's right, variables are not Objects. This means when you see the following, s is not an object, it is not a String, it is a reference to a String String s = "Hello"; This answers many areas of confusion such as; Q: If String is immutable how can I change it. e g. s += "!"; A: You can't in normal Java, you can only change a reference to a String. == compares references, not their contents. To add to the confusion, using == some times works. If you have two immutable values which are the same, the JVM can try to make the references the same too. e.g. String s1 = "Hi", s2 = "Hi"; Integer a = 12, b = 12; In both these case, an object pool is used so the references end up being the same. s1 == s2 and a == b are both true as the JVM has made the references to the same object. However, vary the code a little so the JVM doesn't pool the objects, and == returns false, perhaps unexpectedly. In this case you need to use equals. String s3 = new String(s1); Integer c = -222, d = -222; s1 == s2 // is true s1 == s3 // is false s1.equals(s3) // is true a == b // is true c == d // is false (different objects were created) c.equals(d) // is true For Integer, the object pool starts at -128 up to at least 127 (possibly higher) Java passes references by value All variables are passed by value, even references. This means when you have a variable which is a reference to an object, this reference is copied, but not the object. e.g. public static void addAWord(StringBuilder sb) { sb.append(" word"); sb = null; } StringBuilder sb = new StringBuilder("first "); addWord(sb); addWord(sb); System.out.println(sb); // prints "first word word" The object referenced can be changed, but changes to the copied reference have no effect on the caller. In most JVMs, the Object.hashCode() doesn't have anything to do with memory location A hashCode() has to remain constant. Without this fact hash collections like HashSet or ConcurrentHashMap wouldn't work. However, the object can be anywhere in memory and can change location without your program being aware this has happened. Using the location for a hashCode wouldn't work (unless you have a JVM where objects are not moved) For OpenJDK and the HotSpot JVM, the hashCode() generated on demand and stored in the object's header. Using Unsafe you can see whether the hashCode() has been set and even change it by over Object.toString() does something surprising rather than useful The default behaviour of toString() is to print an internal name for a class and a hashCode(). As mentioned the hashCode is not the memory location, even though it is printed in hexi-decimal. Also the class name, especially for arrays is confusing. For example; a String[] is printed as [Ljava.lang.String; The [ signifies that it is an array, the L signifies it is a "language" created class, not a primitive like byte which BTW has a code of B. and the ;signifies the end of the class. For example say you have an array like String[] words = { "Hello", "World" }; System.out.println(words); print something like [Ljava.lang.String;@45ee12a7 Unfortunately you have to know that the class is an object array, e.g. if you have justObject words, you have a problem and you have to know to call Arrays.toString(words) instead. This break encapsulation in a rather bad way and a common source of confusion on StackOverflow. I have asked different developers at Oracle about this and the impression I got is that it's too hard to fix it now. :(

This article presents the usage of sripted data set in the eclipse's BIRT.

This morning an interesting topic was posted to the Apache ServiceMix user forum, asking the question: To ServiceMix or not ServiceMix. In my mind the short answer is: NO Guillaume Nodet one of the key architects and long time committer on Apache ServiceMix already had his mind set 3 years ago when he wrong this blog post - Thoughts about ServiceMix. What has happened on the ServiceMix project was that the ServiceMix kernel was pulled out of ServiceMix into its own project - Apache Karaf. That happened in spring 2009, which Guillaume also blogged about. So is all that bad? No its IMHO all great. In fact having the kernel as a separate project, and Camel and CXF as the integration and WS/RS frameworks, would allow the ServiceMix team to focus on building the ESB that truly had value-add. But that did not happen. ServiceMix did not create a cross product security model, web console, audit and trace tooling, clustering, governance, service registry, and much more that people were looking for in an ESB (or related to a SOA suite). There were only small pieces of it, but never really baked well into the project. That said its not too late. I think the ServiceMix project is dying, but if a lot of people in the community step up, and contribute and work on these things, then it can bring value to some users. But I seriously doubt this will happen. PS: 6 years ago I was working as a consultant and looked at the next integration platform for a major Danish organization, and we looked at ServiceMix back then and dismissed it due its JBI nature, and the new OSGi based architecture was only just started. And frankly it has taken a long long time to mature Apache Karaf / Felix / Aries and the other pieces in OSGi to what they are today to offer a stable and sound platform for users to build their integration applications. That was not the case 4-6 years ago. Okay No to ServiceMix - what are my options then? So what should use you instead of ServiceMix? Well in my mind you have at least these two options. 1) Use Apache Karaf and add the pieces you need, such as Camel, CXF, ActiveMQ and build your own ESB. These individual projects have regular releases, and you can upgrade as you need. The ServiceMix project only has the JBI components in additional, that you should NOT use. Only legacy users that got on the old ServiceMix 3.x wagon may need to use this in a graceful upgrade from JBI to Karaf based containers. 2) Take a look at fabric8. IMHO fabric8 is all that value-add the ServiceMix project did not create, and a lot more. James Strachan, just blogged today about some of his thoughts on fabric8, JBoss Fuse, and Karaf. I encourage you to take a read. For example he talks about how fabric becomes poly container, so you have a much wider choice of which containers/JVM to run your integration applications. OSGi is no longer a requirement. (IMHO that is very very existing and potentially a changer). I encourage you to check out fabric8 web-site, and also read the overview and motivation sections of the documentation. And then check out some of the videos. After the upcoming JBoss Fuse 6.1 release, the Fuse team at Red Hat will have more time and focus to bring the documentation at fabric8 up to date covering all the functionality we have (there is a lot more), and as well bring out a 1.0 community released using pure community releases. This gives end users a 100% free to use out of the box release. And users looking for a commercial release can then use JBoss Fuse. Best of both worlds. Summary Okay back to the question - to ServiceMix or not. Then NO. Innovation happens outside ServiceMix, and also more and more outside Apache. If you have thoughts then you can share those in comments to this blog, or better yet, get involved in the discussion forum at the ServiceMix user forum. PPS: The thoughts on this blog is mine alone, and are not any official words from my employer.

Background SPNego is RFC 4178 used for negotiation either NTLM or Kerberos based SSO. A typical use case is for web applications to reuse the authentication used by Desktops such as Windows or Linux. In this article, we will explore approaches for SPNego authentication with JBoss Enterprise Application Platform. JBoss Negotiation is the library that provides the SPNego authentication support in JBoss. This library has been integrated in JBoss EAP and WildFly Application Server. Checklist Obtain JBoss EAP from jboss.org. Enable your JavaEE Web Application for SPNego Authentication. Configure JBoss EAP for SPNego. Configure your Browsers for SPNego. Start JBoss EAP. Test your web application. Obtain JBoss EAP from jboss.org Download JBoss EAP 6.2 or newer from http://www.jboss.org/products/eap You can also use WildFly Application Server from http://www.wildfly.org. Your configuration may vary slightly. Enable your JavaEE Web Application for SPNego Authentication It is easier to use a demo web application as a starting point. You can then modify your web application for SPNego authentication. The demo web application we use for this article is called spnego-demo, by my colleague, Josef Cazek. The demo web application is available at https://github.com/kwart/spnego-demo . You can also download the spnego-demo.war from here . Fully configured web application spnego-demo.war can be obtained from this location . Copy the spnego-demo.war in your jboss-eap-6.2/standalone/deployments directory. Configure JBoss EAP for SPNego Authentication You will need to configure a couple of security domains and system properties in JBoss EAP6. There are two ways by which you can configure: either manual editing or using CLI tool. Manual Editing of configuration file standalone.xml in jboss-eap-6.2/standalone/configuration Add system properties to this file. Remember to put this block right after the extensions block (around line 25 of the configuration file). Add security domains to this file. Remember to put these blocks in the block. Using Command Line Interface to update JBoss EAP Go to the bin directory of JBoss EAP 6.2 and run the following. $ cat << EOT > $SPNEGO_TEST_DIR/cli-commands.txt /subsystem=security/security-domain=host:add(cache-type=default) /subsystem=security/security-domain=host/authentication=classic:add(login-modules=[{"code"=>"Kerberos", "flag"=>"required", "module-options"=>[ ("debug"=>"true"),("storeKey"=>"true"),("refreshKrb5Config"=>"true"),("useKeyTab"=>"true"),("doNotPrompt"=>"true"),("keyTab"=>"$SPNEGO_TEST_DIR/http.keytab"),("principal"=>"HTTP/[email protected]")]}]) {allow-resource-service-restart=true} /subsystem=security/security-domain=SPNEGO:add(cache-type=default) /subsystem=security/security-domain=SPNEGO/authentication=classic:add(login-modules=[{"code"=>"SPNEGO", "flag"=>"required", "module-options"=>[("serverSecurityDomain"=>"host")]}]) {allow-resource-service-restart=true} /subsystem=security/security-domain=SPNEGO/mapping=classic:add(mapping-modules=[{"code"=>"SimpleRoles", "type"=>"role", "module-options"=>[("[email protected]"=>"Admin"),("[email protected]"=>"User")]}]) {allow-resource-service-restart=true} /system-property=java.security.krb5.conf:add(value="$SPNEGO_TEST_DIR/krb5.conf") /system-property=java.security.krb5.debug:add(value=true) /system-property=jboss.security.disable.secdomain.option:add(value=true) :reload() EOT $ ./jboss-cli.sh -c --file=$SPNEGO_TEST_DIR/cli-commands.txt This is explained in https://github.com/kwart/spnego-demo/blob/master/README.md We will need a keytab file. In this example, we will use the Kerberos Server using ApacheDS (as explained in Appendix A). $ java -classpath kerberos-using-apacheds.jar org.jboss.test.kerberos.CreateKeytab HTTP/[email protected] httppwd http.keytab Note that the http.keytab has been configured in the security domain called "host" in standalone.conf. So place the keytab file appropriately while correcting the path defined in security domain. More information is available at https://github.com/kwart/kerberos-using-apacheds/blob/master/README.md JBoss EAP will need a keytab file. In this example we use a keytab called as http.keytab Different tools such as ktutil exist to create keytab files. Keytab files contain Kerberos Principals and encrypted keys. It is important to safeguard keytab files. It is very important that JBoss EAP configuration for keytab in the security domain "host" refers to the actual path of the keytab file. Configure your Browsers for SPNego The browsers such as Microsoft IE, Mozilla Firefox, Google Chrome, Apple Safari have different settings for enabling SPNego or Integrated Authentication. Start JBoss EAP Go to the bin directory of JBoss EAP 6.2 and either use standalone.sh (Unix/Linux) or standalone.bat to start your instance. Test your Web Application Assuming you have followed Appendix A steps to start the kerberos server and done kinit, you are ready to test the web application. In this article we have used spnego-demo, we can test that by going to http://localhost:8080/spnego-demo/ You can click on the "User Page" link and you should be able to see the principal name as "[email protected]" Appendix A Local Kerberos Server Download the zip file https://github.com/kwart/kerberos-using-apacheds/archive/master.zip Unzip the zip file into a directory. Build the package using maven. $ mvn clean package Start the Kerberos Server as $ java -jar target/kerberos-using-apacheds.jar test.ldif A krb5.conf file has been created. Login now using [email protected] $ kinit [email protected] Password for [email protected]: secret Launch Firefox via command line from where the kinit was run On MacOSX $open -a firefox http://localhost:8080/spnego-demo/ Appendix B Kerberos Command Line Utilities klist can be used to see the current kerberos tickets. $ klist Credentials cache: API:501:10 Principal: [email protected] Issued Expires Principal Feb 9 21:19:30 2014 Feb 10 07:19:27 2014 krbtgt/[email protected] kdestroy can be used to clear the current kerberos tickets. References SPNego Demo Web Application: https://github.com/kwart/spnego-demo Kerberos Server using ApacheDS: https://github.com/kwart/kerberos-using-apacheds JBoss EAP 6 http://www.jboss.org/products/eap PicketLink Open Source Project: http://www.picketlink.org Troubleshooting https://docs.jboss.org/author/display/PLINK/SPNego+Support+Questions Remember krb5.conf is important for client side kerberos interactions. You can use a environment variable on Unix/Linux/Mac systems called KRB5_CONFIG to point to your krb5.conf Acknowledgement Darran Lofthouse for the wonderful JBoss Negotiation Project and Josef Czacek for the SPNego-demo and Kerberos_using_Apache DS projects.

Lambda expressions are by far the most discussed and promoted feature of Java 8. While I agree that Lambdas are a large improvement I think that some other Java 8 feature go a bit short because of the Lambda hype. In this post I want to show a number of examples from another nice Java 8 feature: Type Annotations. Type Annotations are annotations that can be placed anywhere you use a type. This includes the new operator, type casts, implements clauses and throws clauses. Type Annotations allow improved analysis of Java code and can ensure even stronger type checking. In source code this means we get two new ElementTypes for annotations: @Target({ElementType.TYPE_USE, ElementType.TYPE_PARAMETER}) public @interface Test { } The enum value TYPE_PARAMETER allows an annotation to be applied at type variables (e.g. MyClass). Annotations with target TYPE_USE can be applied at any type use. Please note that the annotations from the following examples will not work out of the box when Java 8 is released. Java 8 only provides the ability to define these types of annotations. It is then up to framework and tool developers to actually make use of it. So this is a collection of annotations frameworks could give us in the future. Most of the examples are taken from the Type Annotations specification and various Java 8 presentations. Simple type definitions with type annotations look like this: @NotNull String str1 = ... @Email String str2 = ... @NotNull @NotBlank String str3 = ... Type annotations can also be applied to nested types Map.@NonNull Entry = ... Constructors with type annotations: new @Interned MyObject() new @NonEmpty @Readonly List(myNonEmptyStringSet) They work with nested (non static) class constructors too: myObject.new @Readonly NestedClass() Type casts: myString = (@NonNull String) myObject; query = (@Untainted String) str; Inheritance: class UnmodifiableList implements @Readonly List { ... } We can use type Annotations with generic type arguments: List<@Email String> emails = ... List<@ReadOnly @Localized Message> messages = ... Graph<@Directional Node> directedGraph = ... Of course we can nest them: Map<@NonNull String, @NonEmpty List<@Readonly Document>> documents; Or apply them to intersection Types: public & @Localized MessageSource> void foo(...) { ... } Including parameter bounds and wildcard bounds: class Folder { ... } Collection c = ... List<@Immutable ? extends Comparable> unchangeable = ... Generic method invocation with type annotations looks like this: myObject.<@NotBlank String>myMethod(...); For generic constructors, the annotation follows the explicit type arguments: 1 new @Interned MyObject() Throwing exceptions: void monitorTemperature() throws @Critical TemperatureException { ... } void authenticate() throws @Fatal @Logged AccessDeniedException { ... } Type annotations in instanceof statements: boolean isNonNull = myString instanceof @NonNull String; boolean isNonBlankEmail = myString instanceof @NotBlank @Email String; And finally Java 8 method and constructor references: @Vernal Date::getDay List<@English String>::size Arrays::<@NonNegative Integer>sort Conclusion Type annotations are an interesting addition to the Java type system. They can be applied to any use of a type and enable a more detailed code analysis. If you want to use Type annotations right now you should have a look at the Checker Framework.

If you are a programmer and have to deal with cryptography issues, you've surely heard about keywords such as encryption, decryption and key management. The last key word, key management, is defined as a group of operations such as generating, exchanging, storing and protecting security artifacts (i.e. keys and certificates). Security artifacts are essential parts of any cryptography operations. Without effective management of such valuable resources, the system can be easily compromised by attackers. Java supports key management by introducing two utilities; Java Keys Store or JKS as short and Java Keytool Utility. Java Key Store is a handy and safe storage to store keys and certificates. Java key store API describes methods and properties of Java keystore class which makes it possible to work with keystore file programmatically. To manage keys and certificates, Java provides a second utility named Java Keytool Utility. Keytool utility is included and delivered with JDK (Java Development Kit) distributions. The Keytool manual introduces and describes various commands and options that are available and provides by Java Keytool utility. Key management is feasible by services that are offered by both Java keystore and Java Keytool utility together. The Key management that Java provides is covering most of programming scenarios. Unfortunately there is only one limitation. Java Keytool utility as the main key management unit does not support any means to import custom created keys to Java keystore. It only supports key generation which results in auto generated keys. This is a major shortcoming in situations where there must be key exchange between application peers. In such situations key specifications are specific to the security models which are agreed between developers. Sometimes the keys are byte streams which are not accompanied with any certificates. These streams are defined as cryptography artifacts and must be protected and saved by Java keystore. One solution to this problem is to use third party utilities such as Openssl. Openssl utility offers a mechanism which is a hack to the unavailability of key import in Java Keytool utility. The trick is to save keys in PKCS12 format using the Openssl utility, and treating the created artifact as a new keystore. Fortunately Java Keytool utility supports key store merge option. The created keystore by Openssl utility then can be merged into any Java keystore by Java Keytool utility. Unfortunately I could not succeed in following this solution. One reason could be that my key had customized specifications such as size and value, plus there was no certificate available to accompany it as well. It seemed that there was no other way to overcome such limitation. I found a solution, pretty easy and quick that helped me achieving the result I wanted without being dependent on any third party tools. One advantage of this method is the use of current options that are offered by both Keytool and Java Keystore utilities. Let’s name this method “Key Replacement”. Firstly a new key must be created, for example, a secret key. The secret key will be auto generated by the Keytool utility and will be saved under a known ALIAS inside a new key store or in an existing one. Open your command prompt and issue the following command: keytool -genseckey -alias mykey -keyalg DES -keysize 56 -storetype jceks -keystore Make sure you have set your Java runtime environment correctly. Description and details of the above command and options can be found on Keytool manual. After issuing the above command, you will be asked to provide a password for the keystore. If the keystore already exists, provide its password; otherwise enter a password to be set for the newly created keystore. If the operation was successful, you can list the keystore entries by issuing the following command: keytool -list -v -storetype JCEKS -keystore The result of list command will be a list of keystore's entries. In our case, the record we seek is something like : Keystore type: JCEKS Keystore provider: SunJCE Your keystore contains 1 entry Alias name: mykey Creation date: Sep 30, 2013 Entry type: SecretKeyEntry As you can see the newly created key is represented by the alias we have set. This key is auto generated by Java Keytool utility. We are one step closer to what we needed. We have created a key entry with the alias we want. The final step is to change the key entry value with our customized value. Remaining steps consists of, locating the target key entry inside the keystore by its alias and change its value with our own value programmatically. The following simple java program will do the job. KeyStore ks = KeyStore.getInstance("JCEKS"); char[] password = "PASSWORD TO KEYSATORE".toCharArray(); java.io.FileInputStream fis = null; try { ks.load(new FileInputStream("PATH TO KEY STORE"), password); } finally { if (fis != null) { fis.close(); } } SecretKey mySecretKey = new SecretKeySpec(Util.hex2byte("5A5A5A5A5A5A5A5A"), 0, Util.hex2byte("5A5A5A5A5A5A5A5A").length, "DES"); KeyStore.SecretKeyEntry skEntry = new KeyStore.SecretKeyEntry(mySecretKey); ks.setEntry("mykey", skEntry, new KeyStore.PasswordProtection(password)); java.io.FileOutputStream fos = null; try { fos = new java.io.FileOutputStream("PATH TO KEYSTORE"); ks.store(fos, password); } finally { if (fos != null) { fos.close(); } } This java program will: · Open the keystore. · Load the key store prior to any operation. · Build a secret key with desired specs (Custom value and Custom length). · Replace the value of target key by using the setEntry() method of keystore object by providing its alias and a new key value. · Finally close and save the keystore object. To double check the modification, use the following code to locate and display the modified key value by loading the keystore object again. try { ks.load(new FileInputStream("PATH TO KEY SOTRE"), password); } finally { if (fis != null) { fis.close(); } } Key key = ks.getKey("mykey ", password); System.out.println("-----BEGIN PRIVATE KEY-----"); System.out.println(new BASE64Encoder().encode(key.getEncoded())); System.out.println("-----END PRIVATE KEY-----"); The steps are straight forward: · Load the key store object. · Load the target key by using the getKey() method and specifying its alias. · Fetch the key value and output its value in PEM format (Base 64 encoding). Voila! That’s our key. This article shows some simple steps which can be used to import a custom created secret key to java keystore. Hope this article will be helpful in cases where the tools such as Openssl utility has no use. Sam,