RexConnect

RexConnect is Java application that provides access to a Rexster-supported graph database. RexConnect adds a powerful, language-agnostic service layer upon Rexster's RexPro interface. It provides methods of data access: server and console. The server mode responds to incoming TCP requests; the console mode offers an interactive interface.

• Current version: 0.5.0
• License: Apache License, Version 2.0

Current Use Cases

The Fabric API, website, and other related projects are written in C#. This makes it more difficult to interact with the Rexster Server, which is a Java project. RexConnect allows these projects to avoid REST/HTTP as a bottleneck, communicating at a lower level instead. Fabric currently uses three distinct graph database scenarios. These scenarios all currently use Titan 0.3.0 with Rexster 2.3.0.

• Cluster: The primary scenario uses a graph database spread across a multi-node server cluster. On each node in the cluster, Rexster Server runs with Titan+Cassandra using storage.backend=embeddedcassandra (see this diagram). A RexConnectServer runs on each node, connecting to Rexster Server via localhost. Fabric's API and Web applications can send Gremlin queries and other commands (via TCP connection) to any cluster node's RexConnect server.

• Integration Tests: The second scenario uses a graph database running on a computer in a local network. Rexster Server runs with Titan+Local using storage.backend=local. A RexConnectServer runs on this same computer, connecting to Rexster Server via localhost. From another development computer in the local network, debug builds and integration tests communicate with the RexConnect server. Fabric integration tests frequently send Gremlin commands like "g.V.remove()" and "g.loadGraphSON('data/FabricTest.json')" to quickly clear and rebuild the local graph database.

• Remote Dev/Debug: The first examples use a RexConnectServer running on the same computer as Rexster, but this is not necessary. During development or debugging, the RexConnect can connect to Rexster Server using the IP address of the Rexster Server computer. RexConnect (server and console) can accept multiple IP addresses for nodes in a graph cluster; these IPs are all passed to the internal RexPro client.

Server

The RexConnectServer responds to TCP requests. These requests are send as JSON data, using RexConnect's server request format. Requests can contain one or more commands, which execute sequentially. After the request's execution completes, RexConnect responds with JSON data in the server response format. Responses include details and data for each command in the request.

Usage

To start the RexConnectServer, execute the "rexConnectServer" script (.sh or .bat) from the project's root directory.

Applications written in any language can connect to RexConnectServer via TCP. See the RexConnect C# Client Wiki page for details about Fabric's actual C# client implementation.

Console

The RexConnectConsole provides an interactive interface with RexConnect. Each console prompt represents the execution of a single command. The command given at the main prompt leads to one or more sub-prompts, where the additional actions/arguments are provided. For clarity and ease-of-use, these sub-prompts provide information about the requested input.

The responses provided by RexConnectConsole are exactly the same as the individual "command" responses provided by RexConnectServer.

Usage

To start the RexConnectConsole, execute the "rexConnectConsole" script (.sh or .bat) from the project's root directory.

A simple example of console usage:

$ bin/rexConnectConsole.sh

"            ---===##\    
"                --==##\  
"  ---===################>
"                --==##/  
"            ---===##/    

RexConnect Console 0.3.2
{rexpro_port=8184, rexpro_graph_name=FabricTest, rexconnect_port=8184, rexpro_hosts=rexster, rexpro_timeout_ms=120000}

-------------------------------------------------------------

# RexConnect> config
#   ...setting (0; string): pretty
#   ...mode (1; int): 1

{
    "timer": 0
}

# RexConnect> query
#   ...script (0; string): g
#   ...params (1; string; opt): 

{
    "timer": 592, 
    "results": [
        "titangraph[local:data/FabricTest]"
    ]
}

# RexConnect> 

Markdown

The console output was designed to play nicely with GitHub's formatting of the C language. Start code blocks with...

```c

...to take advantage of the syntax highlighting.

Documentation

Please see the following Wiki pages for detailed RexConnect usage information:

• Server Request Format
• Server Response Format
• Request Commands
• Usage Examples
• RexConnect C# Client
• Version Notes