GreenVulcano VCL Adapter for Redis (Alpha)

This is the implementation of a GreenVulcano VCL Adapter for the Redis database platform. It's meant to run as an Apache Karaf bundle.

Getting started

Prerequisites

First, you need to have installed Java Development Kit (JDK) 1.7 or above.

Then, you need to have installed Apache Maven (3.5.4 or higher) and Apache Karaf 4.2.6. Please refer to the following links for further reference:

• Apache Maven 3.5.4:
  • Download
  • Installation steps
• Apache Karaf 4.2.6:
  • Download
  • Installation steps: simply extract the Apache Karaf directory in any path you want. Verify that the Apache Karaf installation is operational by running the executable ./bin/karaf from the Apache Karaf root directory (a Karaf shell should be displayed).

Next, you need to install the GreenVulcano engine on the Apache Karaf container. Please refer to this link for further reference.

In order to install the bundle in Apache Karaf to use it for a GreenVulcano application project, you need to install its dependencies. Open the Apache Karaf terminal by running the Karaf executable and type the following command:

karaf@root()> bundle:install mvn:org.apache.commons/commons-pool2/2.6.0 && bundle:install -l 81 mvn:redis.clients/jedis/3.1.0

In case of success, this command will print the ID of the installed bundles:

Bundle ID: n

Before installing the VCL adapter bundle, you have to start the both bundles by specifying their IDs. In the Apache Karaf terminal, type (replacing n with the bundle IDs):

karaf@root()> start n

In case you can't find the bundle ID, just type:

karaf@root()> list | grep Apache Commons Pool
karaf@root()> list | grep Jedis

Having done that, use the list command to make sure both bundles are in Active status.

Then, you need to install the VCL adapter bundle itself in Apache Karaf.

Installing the VCL adapter bundle in Apache Karaf

Clone or download this repository on your computer, and then run mvn install in its root folder:

git clone https://github.com/kylan11/gv-adapter-redis
cd gv-adapter-redis
mvn install

In case of success, the mvn install command will install the VCL adapter bundle in the local Maven repository folder.
After this operation, you have to add the Maven repository project as an Apache Karaf bundle, telling Karaf to load it after the GreenVulcano core bundles, since the VCL adapter requires the GreenVulcano bundles in order to start correctly.
This constraint can be enforced by properly configuring the level of the Karaf bundle: the lower the level number, the earlier the bundle will be loaded by Karaf.

For the VCL adapter bundle, we will use a bundle level higher than the GreenVulcano core bundles (i.e. 80). The following command will install the VCL adapter bundle and set its level to 96 by convention, using the -l attribute:

karaf@root()> bundle:install -l 96 mvn:it.greenvulcano.gvesb.adapter/gvvcl-redis/4.0.0-SNAPSHOT

Bundle ID: x

Make sure that the bundle GreenVulcano ESB Adapter for Redis appears in the list of installed bundles in Installed status and with bundle level (Lvl) equal to 96 (or at least strictly higher than 80).
Then, use its ID to put the bundle in Active status by executing the following command:

karaf@root()> start x

list | grep GreenVulcano ESB Adapter for Redis

Using the VCL adapter in your GreenVulcano project

In order to use the features of the Redis adapter in your GreenVulcano project, you need to define a proper System-Channel-Operation set of nodes. You can do that by manually editing the GVCore.xml file, or by using DeveloperStudio. In that case, you will have to download the dtds/ folder on this repository and replace it with the one in your current project.

Declaring the System-Channel-Operation for the Redis database

Let's assume you want to interact with your database in "localhost". By default, that's gonna be at 127.0.0.1:6379. Insert the <redis-call> XML node in the <Systems></Systems> section of file GVCore.xml. Here's an example:

<System id-system="REDIS" system-activation="on">
    <Channel enabled="true" endpoint="localhost" id-channel="redis-channel" type="RedisDBAdapter">
    	<redis-call name="ciao" type="call">
      	<set name="prova" value="ciao2"/>
         <get name="prova"/>
      </redis-call>
	</Channel>
</System>

Some constraints apply to these XML nodes.

• The <Channel> XML node must comply with the following syntax:

  • endpoint must contain a URI string correctly referencing the hostname and the port of an operational Redis server. In case you're running it locally, you may also simply insert "localhost";

• The <redis-call> XML node must comply with the following syntax:

  • type must be declared and set equal to "call";
  • name must be declared: it defines the name of the Operation node;

• The redis-call node, as of version 1.0, supports three types of operation:

  • get its "key" attribute must be set to the key you're looking to retrieve from the platform;
  • set contains "name", "key" and "value". These respectively represent the operation name, the name of the key you're looking to set, and the value it must be set to. If "value" is left empty, GV will automatically parse the GVBuffer data;
  • delete "name" and "key", representing the name of the key you wish to delete;
  • keys "expression" takes a pattern which lets you specify which key names to retrieve;

When we're done defining our System node, we can now use it in a Service-Operation, such as:

<Services>
            <Description>This section contains a list of all services provided by GreenVulcano ESB</Description>
            <Service group-name="DEFAULT_GRP" id-service="testService"
                     service-activation="on" statistics="off">
                <Operation class="it.greenvulcano.gvesb.core.flow.GVFlowWF"
                           loggerLevel="ALL" name="testOperation"
                           operation-activation="on" type="operation">
                    <Flow first-node="RedisCall">
                        <GVOperationNode class="it.greenvulcano.gvesb.core.flow.GVOperationNode"
                                         id="RedisCall" id-channel="redis-channel"
                                         id-system="REDIS" input="input"
                                         next-node-id="terminated" op-type="call"
                                         operation-name="ciao" point-x="231" point-y="150"
                                         type="flow-node"/>
                        <GVEndNode class="it.greenvulcano.gvesb.core.flow.GVEndNode"
                                   id="terminated" op-type="end" output="input"
                                   point-x="435" point-y="150" type="flow-node"/>
                    </Flow>
                </Operation>
            </Service>
</Services>

You can test these Services selecting them in the Execute section of the GreenVulcano dashboard.

WARNING: This GreenVulcano extension is currently in Alpha stage and its features are still limited and mostly untested. Feel free to report any bugs!