Jorge Bay Gondra

We've just released the <a href="http://docs.datastax.com/en/developer/csharp-dse-graph/latest/">DataStax C# Fluent API</a> for interacting with <a href="https://www.datastax.com/products/datastax-enterprise-graph">DSE Graph</a> using Apache TinkerPop™ Gremlin.Net.

Let's see how this new library can help you write Gremlin traversals from your C# code.

<h3>Gremlin.NET Variant and Driver Integration</h3>

<a href="https://tinkerpop.apache.org/gremlin.html">Gremlin</a> is a functional language used to define <a href="https://en.wikipedia.org/wiki/Graph_traversal">graph traversals</a>. There's a single Gremlin language with different variants based on the native programming language.

In the case of the <a href="https://github.com/datastax/csharp-dse-graph">DataStax C# Fluent API,</a> we are using <a href="http://tinkerpop.apache.org/docs/3.2.7/reference/#gremlin-DotNet">Gremlin.NET language variant</a> that uses C# capitalization and naming conventions, exposing a strongly typed API. You can read more information regarding Gremlin and GLVs on <a href="https://www.datastax.com/dev/blog/datastax-drivers-fluent-apis-for-dse-graph-are-out">this blog post by Kevin Gallardo</a>.

The <a href="https://github.com/datastax/csharp-dse-graph">C# Fluent API for DSE Graph</a> leverages the high-level client driver features of the <a href="https://github.com/datastax/csharp-dse-driver">DataStax Enterprise C# Driver</a>, including:

<ul>
	<li>Automatic cluster discovery</li>
	<li>Built-in load-balancing features</li>
	<li>Datacenter awareness</li>
	<li>Failure recovery policies</li>
	<li>Speculative executions</li>
	<li>Enterprise-grade client authentication</li>
</ul>

It was previously possible to use the C# Driver to execute string representations of groovy gremlin traversals on DSE Graph but this new package enables you to write your graph traversals in C#.

<h3>Getting Started</h3>

Add the package reference to your project file and <a href="https://www.nuget.org/packages/Dse.Graph">obtain it from nuget.org</a>:

<code>dotnet add package Dse.Graph </code>

Add the following using directives:

<code>using Dse; using Dse.Graph; using Gremlin.Net; </code>

To execute traversals, you will need a IDseSession instance that represents a pool of connections to your DSE cluster.

<code>IDseCluster cluster = DseCluster.Builder() .AddContactPoint("127.0.0.1") .Build(); IDseSession session = cluster.Connect(); </code>

Use your IDseSession instances to obtain GraphTraversalSource instances.

<code>GraphTraversalSource g = DseGraph.Traversal(session); </code>

A <code>GraphTraversalSource from Gremlin.NET can be used (and reused) to build traversals.</code>

<code>var traversal = g.V().HasLabel("person").Values<string>("name"); </string></code>

Use the <code>ExecuteGraph()</code> extension methods to execute a traversal:

<code>GraphResultSet result = session.ExecuteGraph(traversal); </code>

Or the async counterpart:

<code>GraphResultSet result = await session.ExecuteGraphAsync(traversal); </code>

Alternatively, Traversals can be executed on the server using the methods that represent <a href="http://tinkerpop.apache.org/docs/current/reference/#terminal-steps">Gremlin terminal steps</a>. In the case of Gremlin.Net variant, those are <code>ToList()</code>, <code>ToSet()</code>, <code>Next()</code>, <code>NextTraverser()</code> and <code>Iterate()</code>, along with <code>Promise()</code> for async traversal execution.

<code>List<string> names = traversal.ToList(); </string></code>

<h3>Wrapping Up</h3>

The documentation for the DataStax C# Driver Fluent API for DSE Graph is located <a href="http://docs.datastax.com/en/developer/csharp-dse-graph/latest/">here</a>.

Your feedback is important to us, you can use the following channels to send comments or questions:

<ul>
	<li>Mailing List: <a href="https://groups.google.com/a/lists.datastax.com/forum/#!forum/csharp-driver-user">https://groups.google.com/a/lists.datastax.com/forum/#!forum/csharp-driver-user</a></li>
	<li>Report issues on JIRA: <a href="https://datastax-oss.atlassian.net/browse/CSHARP/issues">https://datastax-oss.atlassian.net/browse/CSHARP/issues</a></li>
	<li>DataStax Academy Slack: <a href="https://academy.datastax.com/slack">https://academy.datastax.com/slack</a></li>
</ul>

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