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Step-by-Step Guide on Creating a Data Service Using Cassandra Data Source

Introduction

WSO2 Data Services Server provides the capability of exposing data from a Cassandra data-source as a service. This guide will explain how a Data Service can be created using a Cassandra data-source.

Let's begin by creating a simple keyspace add some column family to work with. Here is the Cassandra-cli commands to perform this tasks.

Step 1: Create Keyspace and Column Family


create keyspace Keyspace1;

use Keyspace1;

create column family USER with comparator=UTF8Type and key_validation_class=UTF8Type

and column_metadata=[{column_name: user_id, validation_class: UTF8Type, index_type: KEYS},

{column_name: username, validation_class: UTF8Type},

{column_name: password, validation_class: UTF8Type}];

set USER[user1][username]='dinusha';

set USER[user1][password]='mypwd';

Step 2: Start by giving a name


Lets begin to create the data service by clicking on the 'Create' link in left menu . It requires to enter a name to the Data service. Lets name it as CassandraSampleService and click on Next.

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Figure 1: Create Data Service

Step 3: Enter details about your Cassandra data-source


Next step is to enter details about the data-source which we are using to create the service. Select the Data Source Type as "Cassandra" from the drop down list after you giving a name to the data source.

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Figure 2: Configure Cassandra data-source

Created data source will list and click on "Next" to create the query.

Step 4: Create Query


To extract information you need to create a query along with the structure of the response.

Give a name to the query, and select the data source name from the drop down, which is created in previous step. Specify the CQL query and parameters. Save the query once you enter the details.

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Figure 3: Create New Query

Click on "Add Output Mapping" button to create how the output should look like. Once you have entered the output mapping details click on "Main Configuration" and click on "Save" button.

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Figure 4: Add Output Mappings

Created query will be listed as follows. Click on "Next" to create the operation.

Step 5: Create a web service operation


Enter a name for the operation and select the query from the drop down list. Click on "Save".

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Figure 5: Add operation

Once you click on "Finish" your data service will be created and deployed.

Step 6: Service deployed


You can see the deployed service by clicking on "List" under Main/List left menu. Deployed CassandraSampleService service will be list as follows.

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Figure 6: Deployed Services

Click on the "CassandraSampleService". It will direct to the Service Dashboard. You can click on "Edit Data Service (XML Edit)" and view the created data service as a XML.

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Figure 7: Edit data service

Step 7: Try your service


Click on "Try It" link to invoke the service.

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Figure 8: Invoke service using Try-it