Using jetstreamDB as in-memory Database for Java

June 30th, 2018 by

JetstreamDB is a in-memory database engine for Java that claims to be built for ultra-high speed and the ability of managing complex data structures by storing real Java objects instead of serializing data structures to other database specific formats.

In the following short example I would like to demonstrate how to create and read items from such a database by building a small article management sample app.

Using jetstreamDB for Java

Using jetstreamDB for Java

 

Project Setup

First of all we’re adding some Maven repositories to our project’s pom.xml:

<repositories>
	<repository>
	  <id>jetstream-releases</id>
	  <url>https://maven.jetstream.one/maven2-public</url>
	  <releases>
		<enabled>true</enabled>
	  </releases>
	  <snapshots>
		<enabled>false</enabled>
	  </snapshots>
	</repository>
	<repository>
	  <id>jetstream-snapshots</id>
	  <url>https://maven.jetstream.one/maven2-public-snapshot</url>
	  <releases>
		<enabled>false</enabled>
	  </releases>
	  <snapshots>
		<enabled>true</enabled>
	  </snapshots>
	</repository>
</repositories>

Afterwards just need to add the following dependency:

<dependency>
  <groupId>com.jetstreamdb</groupId>
  <artifactId>jetstreamdb-embedded</artifactId>
  <version>1.0.0-beta1</version>
</dependency>

Sample Application

We’re now implementing a sample application to store and retreive some data from a jetstreamDB…

Root Entity

This is our aggregate, the root of our persisted data:

package com.hascode.tutorial;
 
import java.util.ArrayList;
import java.util.List;
 
public class RootData {
 
  private final List<Article> articles = new ArrayList<>();
 
  public List<Article> getArticles() {
    return articles;
  }
}

Article Entity

This is our article entity

package com.hascode.tutorial;
 
public class Article {
 
  private final String title;
 
  // constructor, getter, setter, tostring ommitted..
}

Command Line App

This is our command line app that allows us to create and list our articles:

package com.hascode.tutorial;
 
import com.jetstreamdb.JetstreamDBInstance;
import java.io.Console;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.List;
 
public class ArticleApp {
 
  private static final String USAGE = "Enter a command 'l': list, 'a': add, 'q': quit 'd': db info\n";
 
  private JetstreamDBInstance<RootData> db;
 
  public ArticleApp() {
    db = JetstreamDBInstance.New("my-articles-db ", RootData.class);
    Path databaseDirectory = Paths.get("").resolve("article-db");
    System.out.printf("creating database directory in %s%n", databaseDirectory.toAbsolutePath());
    db.configuration().properties().setStorageDirectory(databaseDirectory.toFile());
  }
 
  public static void main(String[] args) {
    new ArticleApp().run();
  }
 
  public void run() {
    prompt();
  }
 
  private void prompt() {
    Console console = System.console();
    System.out.println(USAGE);
    String command = console.readLine();
    switch (command) {
      case "q":
        System.out.println("quitting...");
        System.exit(1);
        break;
      case "l":
        List<Article> articles = db.root().getArticles();
        System.out.printf("%d articles found:%n", articles.size());
        articles.forEach(System.out::println);
        prompt();
        break;
      case "a":
        System.out.println("Please enter a title");
        String title = console.readLine();
        List<Article> update = db.root().getArticles();
        update.add(new Article(title));
        db.store(update);
        prompt();
        break;
      case "d":
        System.out.printf("basedir: %s, name: %s%n", db.configuration().getBaseDir(),
            db.configuration().name());
        prompt();
        break;
      default:
        System.out.println("invalid command");
        prompt();
    }
  }
 
}

Running the Application

Now we’d like to add and fetch some data from our application:

We may start the application using our IDE or using Maven in the command line like this:

mvn clean compile exec:java -Dexec.mainClass=com.hascode.tutorial.ArticleApp
[..]
                   `:osssssssso/.
            y+  .oy/.        `:oy/
            ho /h:              `sy`
            hddd/oooooooooooooooo+omdo.
           smmmoy+               d/dmmd/          JetstreamDB
          -mmmm+h/               h/dmmmh
          -mmmmh/y+`           .oy+mmmmd          Version 1.0.0-beta1
          -mmmmdy.:os+-.```.:oso-:dmmmmd
          :mh+- -yo. .:++o+/:``:so``/sdd
         :h/      .+so+//:/+oss/`     .oy.
        :d.   ``      `.:m-.`      ``   /d.
        h+    oo        .d`        +s    so
        d:    oo        .d` /oooo- +s    +y
        h/    oo        .d`        +s    +y
        /h----yo        `:         +y----h+
         sd/::yo                   +y::/ds
          :yo:so                   +s:oy/
            ./ho        .d`        oh/.
              so        .d`        +y
              oo        .d`        +y
              ohoooo+++/+m+/+++oooohy
              .ss+::/+shs/sho/:-:/ss.
       ``````````-:::-.`````-:///-`````````
       ````````````````````````````````````
            ``````````````````````````
creating database directory in /data/project/jetstream-tutorial/article-db
Enter a command 'l': list, 'a': add, 'q': quit 'd': db info
 
l
0 articles found:
Enter a command 'l': list, 'a': add, 'q': quit 'd': db info
 
a
Please enter a title
Some title
Enter a command 'l': list, 'a': add, 'q': quit 'd': db info
 
l
1 articles found:
Article{title='Some title'}
Enter a command 'l': list, 'a': add, 'q': quit 'd': db info
 
d
basedir: article-db, name: my-articles-db
Enter a command 'l': list, 'a': add, 'q': quit 'd': db info
 
a
Please enter a title
another one
Enter a command 'l': list, 'a': add, 'q': quit 'd': db info
 
l
2 articles found:
Article{title='Some title'}
Article{title='another one'}
Enter a command 'l': list, 'a': add, 'q': quit 'd': db info

Internal Structure

Having created those articles we can see that jetstreamDB has created the following files in the designated directory:

/article-db
├── channel_0
│   ├── channel_0_1.dat
│   └── transactions_0.sft
├── ObjectId.oid
├── PersistenceTypeDictionary.ptd
└── TypeId.tid

Tutorial Sources

Please feel free to download the tutorial sources from my Bitbucket repository, fork it there or clone it using Git:

git clone https://bitbucket.org/hascode/jetstreamdb-tutorial.git

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