PostgreSQL, often simply Postgres, is an object-relational database management system (ORDBMS) available for many platforms including Linux, FreeBSD, Solaris, Microsoft Windows and Mac OS X. wikipedia.org

The Java Persistence API, sometimes referred to as JPA, is a Java programming language framework managing relational data in applications using Java Platform, Standard Edition and Java Platform, Enterprise Edition. wikipedia.org

Java is a programming language and a core component of Oracle Corporation's Java Platform. The language derives much of its syntax from C and C++ but has a simpler object model and fewer low-level facilities. wikipedia.org

The Spring Framework is an open source application framework and Inversion of Control container for the Java platform. wikipedia.org

MongoDB is an open source document-oriented NoSQL database system written in the C++ programming language. It manages collections of BSON documents. wikipedia.org

"Elasticsearch is a search server based on Lucene. It provides a distributed, multitenant-capable full-text search engine with a RESTful web interface and schema-free JSON documents. Elasticsearch is developed in Java and is released as open source under the terms of the Apache License." wikipedia.org

Apache Kafka is an open-source message broker project developed by the Apache Software Foundation written in Scala. The project aims to provide a unified, high-throughput, low-latency platform for handling real-time data feeds. wikipedia.org

Cloud computing is a type of Internet-based computing that provides shared computer processing resources and data to computers and other devices on demand. wikipedia.org

MySQL is (as of March 2014) the world's second most widely used open-source relational database management system (RDBMS). wikipedia.org

Java Platform, Enterprise Edition or Java EE is widely used platform for server programming in the Java programming language. The Java platform (Enterprise Edition) differs from the Java Standard Edition Platform (Java SE) in that it adds libraries which provide functionality to deploy

Solr is an open source enterprise search platform from the Apache Lucene project. Its major features include powerful full-text search, hit highlighting, faceted search, dynamic clustering, database integration, and rich document (e.g., Word, PDF) handling. wikipedia.org