Overview

Apache Geode (incubating) is a data management platform that provides real-time, consistent access to data-intensive applications throughout widely distributed cloud architectures.

Geode pools memory, CPU, network resources, and optionally local disk across multiple processes to manage application objects and behavior. It uses dynamic replication and data partitioning techniques to implement high availability, improved performance, scalability, and fault tolerance. In addition to being a distributed data container, Apache Geode is an in-memory data management system that provides reliable asynchronous event notifications and guaranteed message delivery.

Apache Geode is a mature, robust technology originally developed by GemStone Systems in Beaverton, Oregon. Commercially available as GemFire™, the technology was first widely deployed in the financial sector as the transactional, low-latency data engine used in Wall Street trading platforms. Today Apache Geode is used by over 600 enterprise customers for high-scale business applications that must meet low latency and 24x7 availability requirements.

 This project is undergoing incubation at The Apache Software Foundation (ASF), sponsored by the Incubator. Incubation is required of all newly accepted projects until a further review indicates that the infrastructure, communications, and decision making process have stabilized in a manner consistent with other successful ASF projects. While incubation status is not necessarily a reflection of the completeness or stability of the code, it does indicate that the project has yet to be fully endorsed by the ASF.

Main Concepts and Components

Caches are an abstraction that describe a node in a Geode distributed system.

Within each cache, you define data regions. Data regions are analogous to tables in a relational database and manage data in a distributed fashion as name/value pairs. Areplicated region stores identical copies of the data on each cache member of a distributed system. A partitioned region spreads the data among cache members. After the system is configured, client applications can access the distributed data in regions without knowledge of the underlying system architecture. You can define listeners to receive notifications when data has changed, and you can define expiration criteria to delete obsolete data in a region.

Locators provide both discovery and load balancing services. You configure clients with a list of locator services and the locators maintain a dynamic list of member servers. By default, Geode clients and servers use port 40404 and multicast to discover each other.

Geode includes the following features:

• Combines redundancy, replication, and a "shared nothing" persistence architecture to deliver fail-safe reliability and performance.
• Horizontally scalable to thousands of cache members, with multiple cache topologies to meet different enterprise needs. The cache can be distributed across multiple computers.
• Asynchronous and synchronous cache update propagation.
• Delta propagation distributes only the difference between old and new versions of an object (delta) instead of the entire object, resulting in significant distribution cost savings.
• Reliable asynchronous event notifications and guaranteed message delivery through optimized, low latency distribution layer.
• Applications run 4 to 40 times faster with no additional hardware.
• Data awareness and real-time business intelligence. If data changes as you retrieve it, you see the changes immediately.
• Integration with Spring Framework to speed and simplify the development of scalable, transactional enterprise applications.
• JTA compliant transaction support.
• Cluster-wide configurations that can be persisted and exported to other clusters.
• Remote cluster management through HTTP.
• REST APIs for REST-enabled application development.
• Rolling upgrades may be possible, but they will be subject to any limitations imposed by new features.

Geode in 5 minutes

Download and install Geode binaries from http://geode.incubator.apache.org/releases/, or follow the build instructions at https://cwiki.apache.org/confluence/display/GEODE/Building+and+Running+Geode+from+Source to build Geode. 

With a path that contains the bin directory of the installation, start a locator and server:

$ gfsh 

gfsh> start locator --name=locator 

gfsh> start server --name=server 

Create a region:

gfsh> create region --name=region --type=REPLICATE 

Write a client application:

import java.util.Map;
import com.gemstone.gemfire.cache.Region;
import com.gemstone.gemfire.cache.client.*;

public class HelloWorld {
  public static void main(String[] args) throws Exception {
    ClientCache cache = new ClientCacheFactory()
      .addPoolLocator("localhost", 10334)
      .create();
    Region<String, String> region = cache
      .<String, String>createClientRegionFactory(ClientRegionShortcut.CACHING_PROXY)
      .create("region");

    region.put("1", "Hello");
    region.put("2", "World");

    for (Map.Entry<String, String>  entry : region.entrySet()) {
      System.out.format("key = %s, value = %s\n", entry.getKey(), entry.getValue());
    }
    cache.close();
  }
}

Compile and run HelloWorld.java. The classpath should include geode-dependencies.jar.

$ javac -cp /some/path/incubator-geode/geode-assembly/build/install/apache-geode/lib/geode-dependencies.jar HelloWorld.java 
$ java -cp .:/some/path/incubator-geode/geode-assembly/build/install/apache-geode/lib/geode-dependencies.jar HelloWorld

Application Development

Geode applications can be written in a number of client technologies:

• Java using the Geode client API or embedded using the Geode peer API
• Spring Data GemFire or Spring Cache
• Python
• REST
• memcached