Added ODBC driver.

README.md

@@ -1,8 +1,9 @@
 # Hasura Integration Suite
 
-Tools for integrating with Hasura Data Delivery Network (DDN) in two key ways:
+Tools for integrating with Hasura Data Delivery Network (DDN) in three key ways:
 1. Native Data Connector (NDC) toolkit for ingesting data sources into Hasura DDN
 2. SQL-based tools for querying Hasura DDN endpoints
+3. ODBC-based access to Hasura DDN
 
 ## Native Data Connector Development
 
@@ -74,6 +75,20 @@ Lightweight HTTP server for executing SQL queries against Hasura DDN endpoints v
 - Connection pooling
 - Environment-based configuration
 
+## ODBC-based Access to Hasura DDN
+
+### [DDN ODBC Driver](calcite-rs-jni/odbc/README.md)
+The DDN ODBC Driver is a .NET Standard 2.0 library that provides an ODBC-compliant interface to interact with the Hasura DDN platform. This driver allows you to execute SQL queries and retrieve data from your Hasura DDN instance using a familiar ODBC-based API.
+
+#### Features
+- Supports ODBC API for executing SQL queries and retrieving data
+- Provides a simple and intuitive connection management interface
+- Automatically starts and manages a Java application server in the background
+- Supports reading metadata (tables, columns) from the Hasura DDN instance
+- Operates in a read-only mode to ensure data integrity
+
+For detailed usage instructions, please refer to the [DDN ODBC Driver README](DDN-ODBC/README.md).
+
 ## Getting Started
 
 Each component has its own setup and configuration requirements. Please refer to the individual component documentation linked above for detailed instructions.
@@ -93,6 +108,7 @@ For development setup and contribution guidelines, please refer to each componen
 - [JDBC Connector Development Guide](calcite-rs-jni/jdbc/README.md#building-from-source)
 - [Python DB-API Development](calcite-rs-jni/py_graphql_sql/README.md#prerequisites)
 - [SQL HTTP Server Development](calcite-rs-jni/sqlengine/README.md#building-and-running)
+- [DDN ODBC Driver Development](DDN-ODBC/README.md)
 
 ## License
 
@@ -102,6 +118,7 @@ Different components are released under different licenses:
 - Python DB-API: MIT License
 - SQL HTTP Server: MIT License
 - NDC Calcite: License information not specified
+- DDN ODBC Driver: License information not specified
 
 ## Support
 

calcite-rs-jni/odbc/README.md

@@ -0,0 +1,73 @@
+# DDN ODBC Driver
+
+The DDN ODBC Driver is a .NET Standard 2.0 library that provides an ODBC-compliant interface to interact with the Hasura DDN (Data Delivery Network) platform. This driver allows you to execute SQL queries and retrieve data from your Hasura DDN instance using a familiar ODBC-based API.
+
+## Features
+
+- Supports ODBC API for executing SQL queries and retrieving data
+- Provides a simple and intuitive connection management interface
+- Automatically starts and manages a Java application server in the background
+- Supports reading metadata (tables, columns) from the Hasura DDN instance
+- Operates in a read-only mode to ensure data integrity
+
+## Usage
+
+To use the DDN ODBC Driver, follow these steps:
+
+1. Add a reference to the `DDN-ODBC.dll` assembly in your project.
+2. Create an instance of the `DDN_ODBC` class and set the connection string:
+
+   ```csharp
+   var connectionString = "jdbc:ddn://your-hasura-instance.com:8080";
+   var connection = new DDN_ODBC(connectionString);
+   ```
+
+3. Open the connection:
+
+   ```csharp
+   connection.Open();
+   ```
+
+4. Create a command and execute SQL queries:
+
+   ```csharp
+   using (var command = connection.CreateDbCommand())
+   {
+       command.CommandText = "SELECT * FROM users";
+       using (var reader = command.ExecuteReader())
+       {
+           while (reader.Read())
+           {
+               // Process the data
+           }
+       }
+   }
+   ```
+
+5. Close the connection when you're done:
+
+   ```csharp
+   connection.Close();
+   ```
+
+## Architecture
+
+The DDN ODBC Driver is built on top of the .NET Standard 2.0 framework and uses the following key components:
+
+1. `DDN_ODBC` class: The main entry point for the driver, responsible for managing the connection, starting the Java application server, and executing SQL queries.
+2. `DDN_OdbcCommand` class: Implements the ODBC command interface, allowing you to execute SQL queries and retrieve data.
+3. `DDN_OdbcDataReader` class: Implements the ODBC data reader interface, providing a way to iterate over the result set.
+4. `DDNDataParameter` and `DDNDataParameterCollection` classes: Provide a way to manage input parameters for SQL queries.
+5. `SqlQuery` class: Represents a SQL query to be executed on the Hasura DDN instance.
+
+The driver uses an embedded Java application server to communicate with the Hasura DDN instance. The Java application server is started and managed by the `DDN_ODBC` class, and all SQL queries are executed through this server.
+
+## Limitations
+
+- The driver currently operates in a read-only mode, meaning that it does not support any write operations (insert, update, delete) on the Hasura DDN instance.
+- Transactions are not supported, as the Hasura DDN instance is designed for read-only access.
+- The driver does not provide any advanced features like connection pooling or asynchronous operations. It focuses on providing a basic, ODBC-compliant interface to interact with the Hasura DDN platform.
+
+## Contributing
+
+If you encounter any issues or have suggestions for improvements, please feel free to create a new issue or submit a pull request on the project's GitHub repository.