Fallen-8 is an in-memory graph database implemented in C#. Its focus is to provide raw speed for heavy graph algorithms.

• Properties on vertices and edges
• Indexes on vertices and edges
• Plugins for indexes, algorithms and services
• Checkpoint persistency

• Enterprise Search (Semantic adhoc queries on multi-dimensional graphs)
• Lawful Interception (Mass analysis)
• E-Commerce (Bid- and portfolio-management)

Fallen-8 makes use of git submodules, that's why they have to be cloned too.

$ git clone --recursive [email protected]:cosh/fallen-8.git

var fallen8 = new Fallen8();

//start the built-in services
fallen8.ServiceFactory.StartGraphService();
fallen8.ServiceFactory.StartAdminService();

Service plugins are the easiest way to add use-case specific functionality on top of Fallen-8. There are two standard plugins available:

• Admin REST service
• Graph REST service

They are started by default using the StartUp project.

[Fallen-8_Graph_Service:config] URIPattern (n/a, using default): Fallen-8_Graph_Service
[Fallen-8_Graph_Service:config] IPAddress (n/a, using default): 127.0.0.1
[Fallen-8_Graph_Service:config] Port (n/a, using default): 9923
Fallen-8 Graph Service Plugin v1.0.0
   -> Service is started at http://127.0.0.1:9923/Fallen-8_Graph_Service/1.0/REST
[Fallen-8_Admin_Service:config] URIPattern (n/a, using default): Fallen-8_Admin_Service
[Fallen-8_Admin_Service:config] IPAddress (n/a, using default): 127.0.0.1
[Fallen-8_Admin_Service:config] Port (n/a, using default): 9923
Fallen-8 Admin Service Plugin v2.3.0
   -> Service is started at http://127.0.0.1:9923/Fallen-8_Admin_Service/1.0/REST
Enter 'shutdown' to initiate the shutdown of this instance.

The lovely .Net is able to help you using the REST services. Just take a look at the webservice help:

• Admin service: http://127.0.0.1:9923/Fallen-8_Admin_Service/1.0/REST/help
• Graph service: http://127.0.0.1:9923/Fallen-8_Graph_Service/1.0/REST/help

In order to create your own Service plugin four steps need to be taken. The following example code can be found in Examples/ServicePlugin. There is a slightly bigger "benchmark" service which could act as some kind of bluprint service for you located in Examples/Benchmark.

The webservice contract defines the functions which you would like to add on top of Fallen-8. It's a plain old service contract with one extension: you have to implement the IRESTService interface.

	[ServiceContract (Namespace = "Fallen-8-Training", Name = "Fallen-8 training service")]
    public interface IHelloService : IRESTService
    {
        /// <summary>
        /// Say hello to someone
        /// </summary>
        /// <param name="who">The one you like to say hello to</param>
        /// <returns>Hello to someone</returns>
        [OperationContract (Name = "Hello")]
        [Description ("[F8Training] Hello: Says hello to someone.")]
        [WebGet (UriTemplate = "/hello/{who}", ResponseFormat = WebMessageFormat.Json)]
        String Hello (String who);
    }

Create a new IHelloService implementation and implement the methods. In this first example don't do anything in the "IRESTService", "IFallen8Serializable" and "IDisposable" implementations.

	public class HelloService : IHelloService
    {
   		...
        #region IHelloService implementation

        public string Hello (string who)
        {
            return "hello " + who;
        }

        #endregion
		...
    }

The actual Fallen-8 plugin needs to extend the ARESTServicePlugin abstract class. The most important field is the "PLUGIN_NAME". This is the unique name of your plugin. You'll need it later in order to start the plugin. Interesting regions:

• IFallen8Serializable: in case the plugin needed to persist sth during the "save"-phase of the checkpoint persistency you are able to deserialize the necessary parameters
• IPlugin: All methods which are responsible for the plugin mechanics like creation/versioning/nameing etc.

public sealed class HelloServicePlugin : ARESTServicePlugin
    {
        public const string PLUGIN_NAME = "Fallen-8_Hello_Service";
        public const string MANUFACTURER = "Henning Rauch";
        public const string PLUGIN_DESCRIPTION = "Fallen-8 Hello Service Plugin";
        public const string VERSION = "1.0.0";
        public const double RESTVERSION = 1.0;

        #region IFallen8Serializable implementation

        public override IRESTService LoadServiceFromSerialization (SerializationReader reader, Fallen8 fallen8)
        {
            return new HelloService ();
        }

        #endregion

        #region IPlugin implementation

        public override IRESTService CreateService (Fallen8 fallen8, IDictionary<string, object> parameter)
        {
            return new HelloService ();
        }

        ...
        #endregion
    }

This is pretty simple now. Just tell Fallen-8 what you like to have and you'll get it.

IService helloService;
            if (fallen8.ServiceFactory.TryAddService (out helloService, "Fallen-8_Hello_Service", "Hello API", null)) {
                if (helloService.TryStart ()) {
                    Console.WriteLine ("Wohooo.");
                }
            }

After you started the project you'll see this:

[Fallen-8_Hello_Service:config] URIPattern (n/a, using default): Fallen-8_Hello_Service
[Fallen-8_Hello_Service:config] IPAddress (n/a, using default): 127.0.0.1
[Fallen-8_Hello_Service:config] Port (n/a, using default): 9923
Fallen-8 Hello Service Plugin v1.0.0
   -> Service is started at http://127.0.0.1:9923/Fallen-8_Hello_Service/1.0/REST
Wohooo.
Enter 'shutdown' to initiate the shutdown of this instance.

just try it: http://127.0.0.1:9923/Fallen-8_Hello_Service/1.0/REST/hello/world

There are plenty of benchmarks in the world. This is a puristic one that focusses on the raw traversal speed of Fallen-8. It creates an equally distributed graph with a defined number of vertices and edges. Afterwards you are able to measure the traversals per second for your graph in Fallen-8. In order to start the benchmark, compile the Examples/Benchmark project and start it with Admin-Rights. It uses the service plugin pattern described in the last point and provides two web-services

• CreateGraph: http://127.0.0.1:9923/Fallen-8_Benchmark_Service/1.0/REST/CreateGraph?nodes=1000&edgesPerNode=500 (creates a graph with 1000 nodes and 500 edges per node)
• algorithm/tps: http://127.0.0.1:9923/Fallen-8_Benchmark_Service/1.0/REST/algorithm/tps?iterations=10000 (takes every node of the graph and iterates over all it's edges in order to "touch" the neighbor vertex)

As always there is a .Net help available: http://127.0.0.1:9923/Fallen-8_Benchmark_Service/1.0/REST/help

Graph databases - Henning Rauch

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Copyright (c) 2012-2015 Henning Rauch

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