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Connect to JSON Services as a Federated Tables in MySQL

Use the CData Cloud Hub to set up federated tables for JSON services in MySQL .

You can use the CData Cloud Hub to set up federated tables in MySQL for JSON services. The Cloud Hub provides a MySQL interface for JSON: After configuring a virtual MySQL database for JSON, you can create a server and tables using the FEDERATED Storage Engine in MySQL. You can then work with JSON services just as you would local MySQL tables.

The CData Cloud Hub provides a pure MySQL, cloud-to-cloud interface for JSON, allowing you to easily query live JSON services alongside existing MySQL data — all without replicating the data. Using optimized data processing out of the box, the CData Cloud Hub pushes all supported SQL operations (filters, JOINs, etc) directly to JSON, leveraging server-side processing to quickly return JSON services.

Create a Virtual MySQL Database for JSON Services

CData Cloud Hub uses a straightforward, point-and-click interface to connect to data sources and generate APIs.

  1. Login to Cloud Hub and click Databases.
  2. Select "JSON" from Available Data Sources.
  3. Enter the necessary authentication properties to connect to JSON.

    See the Getting Started chapter in the data provider documentation to authenticate to your data source: The data provider models JSON APIs as bidirectional database tables and JSON files as read-only views (local files, files stored on popular cloud services, and FTP servers). The major authentication schemes are supported, including HTTP Basic, Digest, NTLM, OAuth, and FTP. See the Getting Started chapter in the data provider documentation for authentication guides.

    After setting the URI and providing any authentication values, set DataModel to more closely match the data representation to the structure of your data.

    The DataModel property is the controlling property over how your data is represented into tables and toggles the following basic configurations.

    • Document (default): Model a top-level, document view of your JSON data. The data provider returns nested elements as aggregates of data.
    • FlattenedDocuments: Implicitly join nested documents and their parents into a single table.
    • Relational: Return individual, related tables from hierarchical data. The tables contain a primary key and a foreign key that links to the parent document.

    See the Modeling JSON Data chapter for more information on configuring the relational representation. You will also find the sample data used in the following examples. The data includes entries for people, the cars they own, and various maintenance services performed on those cars.

  4. Click Test Database.
  5. Click Privileges -> Add and add the new user (or an existing user) with the appropriate permissions.

With the virtual database created, you are ready to connect to JSON services from any MySQL client.

Create a FEDERATED Server and Tables for JSON Services

After you have configured and started the service, create a FEDERATED server to simplify the process of creating FEDERATED tables:

Create a FEDERATED Server

The following statement will create a FEDERATED server based on the Cloud Hub. Note that the username and password of the FEDERATED server must match a user account you defined on the Cloud Hub.

CREATE SERVER fedJSON
FOREIGN DATA WRAPPER mysql
OPTIONS (USER 'cloud_hub_user', PASSWORD 'cloud_hub_passwd', HOST 'myinstance.cdatacloud.net', PORT 3306, DATABASE 'jsondb');

Create a FEDERATED Table

To create a FEDERATED table using our newly created server, use the CONNECTION keyword and pass the name of the FEDERATED server and the remote table (people). Refer to the following template for the statement to create a FEDERATED table:

CREATE TABLE fed_people (
  ...,
  [ personal.name.first ]  TYPE(LEN),
  [ personal.name.last ]  TYPE(LEN),
  ...,
)
ENGINE=FEDERATED
DEFAULT CHARSET=utf8
CONNECTION='fedJSON/people';

NOTE: The table schema for the FEDERATED table must match the remote table schema exactly. You can always connect directly to the Cloud Hub using any MySQL client and run SHOW COLUMNS FROM people to get the table schema.

Execute Queries

You can now execute queries to the JSON FEDERATED tables from any tool that can connect to MySQL, which is particularly useful if you need to JOIN data from a local table with data from JSON. Refer to the following example:

SELECT 
  fed_people.[ personal.name.first ], 
  local_table.custom_field 
FROM 
  local_table 
JOIN 
  fed_people 
ON 
  local_table.foreign_[ personal.name.first ] = fed_people.[ personal.name.first ];