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Spring Boot

Boot-Pom1

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.example</groupId>
    <artifactId>myproject</artifactId>
    <version>0.0.1-SNAPSHOT</version>

    <!-- Inherit defaults from Spring Boot -->
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.2.1.RELEASE</version>
    </parent>

Boot-Pom2

<!-- Add typical dependencies for a web application -->
<dependencies>
  <dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
  </dependency>
</dependencies>

Boot-Pom3

<!-- Package as an executable jar -->
<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
        </plugin>
    </plugins>
</build>

Boot-GreetingController

@RestController
public class GreetingController {

  private static final String template = "Hello, %s!";
  private final AtomicLong counter = new AtomicLong();

  @RequestMapping("/greeting")
  public Greeting greeting(@RequestParam(value="name", defaultValue="World") String name) {
    return new Greeting(counter.incrementAndGet(),
    String.format(template, name));
  }
}

Boot-GreetingPojo

public class Greeting {

  private final long id;
  private final String content;

  public Greeting(long id, String content) {
    this.id = id;
    this.content = content;
  }
  public long getId() {
    return id;
  }
  public String getContent() {
    return content;
  }
}

Boot-GreetingApplication

@RestController
@ComponentScan
@EnableAutoConfiguration
public class Application {

  public static void main(String[] args) {
    SpringApplication.run(Application.class, args);
  }
}

Boot-Build-and-Run

Maven plugin

mvn spring-boot:run

Maven Build

mvn clean package

Maven Build

Java -jar target/gs-rest-service-0.1.0.jar

I

mostly

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Cassandra

Cassandra-What-is-it

• a hot topic at Target maybe too hot
• Decentralized
• Scalability
• Fault-tolerant
• MapReduce support Dont use Hadoop though
• Query language

Cassandra-Spring-Data

• To the rescue at least I like it :)
• Spring conventions - repositories, templates
• Annotated POJOs
• Cluster and Session support
• QueryBuilders Put your speaker notes here. You can see them pressing 's'.

Cassandra-PersonPojo

@Table
public class Person {

  @PrimaryKey
  private String id;

  private String name;
  private int age;

  //constructor(s), getters, setters

}

Cassandra-CrudRepository

public interface CrudRepository<T, ID extends Serializable>
extends Repository<T, ID> {

  <S extends T> S save(S entity);

  T findOne(ID primaryKey);

  Iterable<T> findAll();

  Long count();

  void delete(T entity);

  boolean exists(ID primaryKey);  

  //
}

Cassandra-PagingAndSorting

public interface PagingAndSortingRepository<T, ID extends Serializable>
extends CrudRepository<T, ID> {

  Iterable<T> findAll(Sort sort);

  Page<T> findAll(Pageable pageable);
}

Cassandra-Main

  Cluster cluster = Cluster.builder().addContactPoints(InetAddress.getLocalHost()).build();
  Session session = cluster.connect("mykeyspace");
  CassandraOperations cassandraOps = new CassandraTemplate(session);
  cassandraOps.insert(new Person("1234567890", "David", 40));
  Select s = QueryBuilder.select().from("person");
  s.where(QueryBuilder.eq("id", "1234567890"));
  LOG.info(cassandraOps.queryForObject(s, Person.class).getId());
  cassandraOps.truncate("person");

Cassandra-Repositories-continued

public interface UserRepository extends CrudRepository<User, Long> {

  Long countByLastname(String lastname);
}

Cassandra-Repositories-continued

public interface UserRepository extends CrudRepository<User, Long> {

  Long deleteByLastname(String lastname);

  List<User> removeByLastname(String lastname);

}

Hazelcast

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Hazelcast

What is Hazelcast?

Hazelcast is an in-memory open source software data grid based on Java. -- Wikipedia

Hazelcast-Features

• In-Memory Java Caching
• NoSQL Key Value Store
• 4MB JAR library
• Drop-In with no dependencies
• Apache 2.0 License

What is Hazelcast?

Scalable

Highly available

Highly performant

Hazelcast-Java-Functions

• The following slides are just taken from hazelcast.org
• I'm often lazy

Hazelcast- Map

public class DistributedMap {
  public static void main(String[] args) {
    Config config = new Config();
    HazelcastInstance h = Hazelcast.newHazelcastInstance(config);
    ConcurrentMap<String, String> map = h.getMap("my-distributed-map");
    map.put("key", "value");
    map.get("key");

    //Concurrent Map methods
    map.putIfAbsent("somekey", "somevalue");
    map.replace("key", "value", "newvalue");
  }
}

Hazelcast-Topic

public class DistributedTopic implements MessageListener<String> {
  public static void main(String[] args) {
    Config config = new Config();
    HazelcastInstance h = Hazelcast.newHazelcastInstance(config);
    ITopic<String> topic = h.getTopic("my-distributed-topic");
    topic.addMessageListener(new DistributedTopic());
    topic.publish("Hello to distributed world");
  }

@Override
  public void onMessage(Message<String> message) {
    System.out.println("Got message " + message.getMessageObject());
  }
}

Hazelcast-Lock

public class DistributedLock {
  public static void main(String[] args) {
    Config config = new Config();
    HazelcastInstance h = Hazelcast.newHazelcastInstance(config);
    Lock lock = h.getLock("my-distributed-lock");
    lock.lock();
    try {
      //do something here
      } finally {
        lock.unlock();
      }
    }
  }

Hazelcast-EntryProcessor

public static class IncEntryProcessor extends AbstractEntryProcessor<String, Integer> {
    @Override
    public Object process(Map.Entry<String, Integer> entry) {
      int oldValue = entry.getValue();
      int newValue = oldValue + 1;
      entry.setValue(newValue);
      return null;
    }
  }

Hazelcast-EntryProcessor2

public static void main(String[] args) {
  HazelcastInstance hz = Hazelcast.newHazelcastInstance();
  IMap<String, Integer> map = hz.getMap("map");
  map.put("key", 0);
  map.executeOnKey("key", new IncEntryProcessor());
  System.out.println("new value:" + map.get("key"));
}

Hazelcast-Aggregation

public class DistributedAggregation {
  public static void main(String[] args) {
    Config config = new Config();
    HazelcastInstance h = Hazelcast.newHazelcastInstance(config);
    IMap<String, Integer> salaries = h.getMap("salaries");
    fillInSalaries(salaries);
    Supplier<String, Integer, Integer> supplier = Supplier.all();
    int sum = salaries.aggregate(supplier, Aggregations.integerSum());
    System.out.println("Aggregated sum: " + sum);
  }
}

Hazelcast-OtherTypes

• Multimap
• JCache
• Queue
• Executor Service
• IAtomicLong
• Aggregation
• Map Reduce