Follow the instructions below to create a data service using a Cassandra data-source.
First, create a simple keyspace and add some columns to work with. Here is the Cassandra-cli commands to perform this tasks:
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';
1. Log on to the Data Services Server Management Console.
2. Click the "Main" tab and select the "Create" link under "Data Services."
3. The "Create Data Service" page appears. Fill in the fields and click "Next." The Data Service name is mandatory.
Info:
For more information on Advanced Configurations in creating data services, refer to the Transaction Handling section.
4. The "Data Sources" page appears. Click on the "Add New Data Source" link and add your Data Source details. Then click "Save."
For a Cassandra data source, select the data source type as Cassandra. For example,
Note:
Before saving, you can click on the 'Test Connection' button. If the database connection is successful, you will get a 'connection is successful' message:
5. After saving, the added data source page appears. You can edit or delete the Data Source. To proceed click "Next."
6. The "Queries" page appears.
Initially your service does not include any queries. Click on 'Add New Query' to add a new query, input/output mappings, events etc. to your Data Service.
To extract information you need to create a query relevant to the structure of the response. Give a name to the query, and select the data source which was created in the previous step. Specify the CQL query and parameters and click Save.
Query ID : getUsers
Data Source : CassandraDatasource
CQL : select 'key', 'username', 'password' from USER
To define how the output looks like, click the Add Output Mapping button. For example,
Once you have entered the output mapping details, click on Main Configuration and then the Save button.
7. You have added one query to your data service configuration. You can edit or delete your query. To continue, click "Next."
8. The "Operations" page appears. Click the "Add new operation" link to create an operation.
Select a query to be executed when this operation is called. For example, 
Click "Save" once done.
9. The Data Service configuration is done. Click "Finish." (You can continue to add resources by clicking the Next button if you like)
10. You will be navigated to the "Deployed services" page.
From here, you can manage your service.