jackson-module-osgi's Introduction

jackson-module-osgi

This module provides a way to inject OSGI services into deserialized objects. Thanks to the JacksonInject annotations, the OsgiJacksonModule will search for the required service in the OSGI service registry and injects it in the object while deserializing.

Usage

For example, imagine a drawing software that persists shapes in JSON documents (on file system, mongodb or orientdb). The Shape object needs a DrawingService that is in charge of drawing shapes.

interface Drawable {
    void draw();
}

interface DrawingService {
    void draw(Drawable drawable);
}
	
class Shape implements Drawable {
    public int x;
    public int y;

    private DrawingService drawingService;

    public Shape(@JacksonInject DrawingService drawingService)
    {
        this.drawingService = drawingService;
    }

    @Override
    public void draw()
    {
        drawingService.draw(this);
    }
}

To deserialize shapes and to inject the drawing service :

ObjectMapper mapper = new ObjectMapper();
mapper.registerModule(new OsgiJacksonModule(bundleContext));
Shape shape = mapper.reader().forType(Shape.class).readValue("{\"x\":13,\"y\":21}");

The module supports OSGI filters to select the service more accurately :

public Shape(@JacksonInject(value = "(provider=ACME)") DrawingService drawingService)
{
    this.drawingService = drawingService;
}

Limitations

injecting value in setter is not supported
dynamicity is not supported. If the service is unregistered, the deserialized object will keep the old service reference.

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