Custom Backends

Create custom data backends for qqq

Overview

Backends in qqq provide data storage and retrieval. While qqq includes backends for RDBMS, MongoDB, and more, you can create custom backends for specialized needs.

Backend Interface

Implement the QBackendModule interface:

Java

public class MyCustomBackend implements QBackendModule {
    @Override
    public String getName() {
        return "my-custom-backend";
    }
    
    @Override
    public QueryOutput executeQuery(QueryInput input) {
        // Implement query logic
    }
    
    @Override
    public InsertOutput executeInsert(InsertInput input) {
        // Implement insert logic
    }
    
    @Override
    public UpdateOutput executeUpdate(UpdateInput input) {
        // Implement update logic
    }
    
    @Override
    public DeleteOutput executeDelete(DeleteInput input) {
        // Implement delete logic
    }
}

Registration

Java

qInstance.addBackend(new QBackendMetaData()
    .withName("myBackend")
    .withBackendType("my-custom-backend")
    .withSettings(Map.of(
        "connectionString", "custom://localhost:1234"
    )));

Use Cases

Custom backends are useful for:

Legacy system integration

Specialized databases

External API wrappers

File-based storage

In-memory testing

Best Practices

Handle connection pooling appropriately

Implement proper error handling

Support transactions where possible

Add logging for debugging

Next Steps

Custom Actions - Extend action system

Creating qBits - Package as qBit