Application Development

In this chapter, we will discuss the development of applications backed by Apache Cassandra. This subject is one of the most misunderstood areas of Cassandra. Too often, developers assume that their years of developing with relational databases have prepared them for working with a distributed database such as Apache Cassandra. Unfortunately, their familiar, relational foundations lead them down the wrong path.

In this chapter, we will discuss the following topics:

• Common mistakes made at the application and data model levels
• Driver selection
• Appropriate connection properties
• Handling simple and complex result sets in Java
• Loading data without overwhelming your nodes

By the end of this chapter, you will understand how to build Java applications to work with Apache Cassandra. These example applications will start small and simple, and grow in complexity...

Getting started

The first steps to building an application for use with Apache Cassandra are both important to get right, and easy to get wrong. Here we will cover some fundamental questions about whether or not Cassandra is even the correct data store for the application in question.

But first, let's start with an overview of what the wrong path looks like.

The path to failure

As most developers are used to working with relational databases, the typical path to failure starts with a data model that closely resembles one found in a RDBMS. A loading job is then written, which only succeeds in crashing their nodes every couple of hours.

Finally, once the data is there, they build their application around a RDBMS framework...

Building a Java application

In this section, we will build a Java application to interact with our Apache Cassandra cluster. We will start with some simple examples, and build our way up to something more complex.

Finally, we will cover writing a job to load data, and discuss adjustments to allow it to work at a large scale.

Driver dependency configuration with Apache Maven

Inside our integrated developer environment (IDE), we will create a new Maven Java project. I'll specify the package as PacktCassDev. Then, we'll need to make sure that our pom.xml file is configured with the desired version of the DataStax Java driver:

<dependencies>
    <dependency>
        <groupId>com.datastax.cassandra<...

Summary

This chapter was designed with a specific goal in mind—that of bridging the knowledge gap between Apache Cassandra DBAs and software developers. Often, developers only have experience with relational databases, and sometimes not even that much.

This chapter was as much about educating developers as it was about providing perspective for the DBAs. That is to say, as a DBA sometimes it is important to see the world through the eyes of your dev team.

We started out in this chapter by covering correct use cases and database selection. Then we began to discover the DataStax Java driver, its behaviors and configurations, and how it interacts with Apache Cassandra.

Finally, we built a series of short programs of increasing complexity. Each program used the same connection class, and iteratively explained how to get from problem definition to program execution.

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