VSCP really heavily on the black box principle and need to maintain a high level of abstraction to be able to be used in a wide range of applications. This is the reason why the VSCP specification is so large and complex.
The Black Box Principle is a concept in systems theory, engineering, and cybernetics that emphasizes understanding and interacting with a system solely based on its observable inputs and outputs, without requiring knowledge of its internal structure or mechanisms. The system is treated as a "black box" — something whose inner workings are hidden or irrelevant to its external behavior.
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Focus on External Behavior
- The principle centers on how the system responds to various inputs and the outputs it produces, rather than how it achieves those results internally.
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Abstraction
- By abstracting away the internal complexity, users and designers can focus on how the system interacts with the environment or other systems.
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Encapsulation
- Internal details are encapsulated, meaning they are hidden from external observers or users. This prevents unnecessary complexity and promotes modularity.
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Interchangeability
- Systems designed using the black box principle can often be replaced or modified as long as their external behavior (inputs and outputs) remains consistent.
- Devices and Machines: A car’s engine can be treated as a black box when interacting with the car through the accelerator pedal, ignoring the detailed mechanics.
- Electronics: Users interact with a smartphone through its interface, without needing to understand the circuits and code within it.
- APIs (Application Programming Interfaces): Developers use APIs as black boxes, relying on documented inputs and outputs without needing to know the underlying code.
- Modular Programming: Functions or modules in software can be treated as black boxes by other parts of the program.
- Feedback Loops: In control systems, the black box principle is used to analyze how a system responds to feedback without requiring internal details.
- Biological Systems: For example, the human brain can be treated as a black box in behavioral studies by analyzing stimulus-response patterns.
- Black-Box Testing: In software testing, test cases are designed based on the external specifications of a program without any knowledge of its internal code or logic.
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Simplification
- By focusing only on inputs and outputs, complex systems become easier to understand, manage, and interact with.
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Modularity
- Systems can be designed as independent components that interact via defined interfaces, allowing for easier maintenance, replacement, and scalability.
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Interoperability
- Ensures that systems with different internal designs can work together, as long as they adhere to the same external specifications.
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Encourages Innovation
- Developers or users can focus on improving external functionality or integrating the system into larger frameworks without being constrained by internal implementation details.
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Lack of Insight
- Hiding the internal mechanisms can lead to a lack of understanding, which might be critical in debugging or optimizing the system.
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Assumptions About Behavior
- The principle relies on assumptions about consistent external behavior, which might not hold true if the internal system changes or malfunctions.
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Complex Interdependencies
- In tightly coupled systems, treating components as black boxes may oversimplify interactions and obscure critical dependencies.
The VSCP Decision Matrix is a key feature of the Very Simple Control Protocol (VSCP) that allows devices to autonomously process events and take appropriate actions based on predefined rules. It acts as a programmable logic table that enables distributed intelligence within a VSCP network.
The decision matrix is implemented in each device and provides flexibility for customizing its behavior without requiring complex programming or centralized control.
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Autonomous Event Handling
- Devices can independently process incoming events and decide how to respond, reducing the need for a centralized controller.
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Distributed Intelligence
- The decision-making logic is distributed across all devices in the network, making the system scalable and robust.
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Customization
- Users can configure the decision matrix to tailor device behavior to specific application needs.
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Interoperability
- The matrix operates within the standardized VSCP event model, ensuring seamless interaction between devices.
The decision matrix consists of rows, with each row representing a rule or condition for handling events. Each row contains the following fields:
- Specifies the conditions for matching incoming events:
- Event Class: Filters events based on their functional category (e.g., measurement, control, or security).
- Event Type: Further refines the match based on specific event types within a class.
- Priority: Matches events with a certain priority level.
- Zone/Sub-Zone: Matches events based on geographical or logical zones in the system.
- Defines the action to be taken if the event matches the filter criteria. Actions can include:
- Sending a specific VSCP event.
- Activating or deactivating outputs.
- Triggering a predefined device function (e.g., resetting a counter or toggling a state).
- Provides additional data or configuration required to execute the action. For example:
- The target GUID of a device to send a message to.
- Specific values to include in the outgoing event payload.
- A flag to enable or disable a specific rule in the matrix without deleting it.
| Row | Event Filter (Class/Type/Zone) | Action | Action Parameters | Enabled |
|---|---|---|---|---|
| 1 | Measurement/Temperature/Zone 1 | Send Event | Alert Event | Yes |
| 2 | Control/Turn On/Zone 2 | Activate Output | Output 1 | Yes |
| 3 | Measurement/Humidity/Zone 1 | Send Event | Humidity Warning Event | No |
| 4 | Security/Alarm/Any Zone |
In the context of VSCP (Very Simple Control Protocol), the black box principle is a foundational concept:
- Devices as Black Boxes: VSCP devices are treated as black boxes that send and receive events. Their internal workings (hardware, firmware, or software) are irrelevant to how they interact with the VSCP network.
- Standardized Interfaces: Devices expose their functionality via registers and events, allowing controllers to interact with them without needing detailed knowledge of their internal design.
- Encapsulation of Complexity: The protocol hides the complexity of device implementation behind a standardized abstraction, enabling interoperability and scalability in diverse systems.
The Black Box Principle is a powerful abstraction tool that simplifies the design, analysis, and interaction with complex systems. By focusing on inputs and outputs while hiding internal complexity, it promotes modularity, interoperability, and efficiency across various fields, including engineering, software, and systems theory.
Events are the core of the VSCP protocol. They are used to send information between nodes in the VSCP network. Events are sent from a source node to a destination node. The source node is the node that sends the event and the destination node is the node that receives the event. The destination node can be a specific node or a group of nodes. The event contains information about the event type, the priority of the event, and the data associated with the event. The data can be of different types, such as integer, floating point, string, etc. Events are used to send information about the state of a node, to control the behavior of a node, or to request information from a node. Events are sent asynchronously, meaning that the source node does not wait for a response from the destination node. This allows the source node to continue its operation without being blocked by the event transmission.
Even if VSCP have events to Turn something On it does not demand that the receiving node actually turns something on. It is up to the receiving node to decide what to do with the event. This is the black box principle in action. The sender does not need to know what the receiver does with the event. It is up to the receiver to decide what to do with the event. This makes the VSCP protocol very flexible and easy to use in a wide range of applications.
So this the way to think also when adding now events to the protocol. Class/types should be general and not too specific. So when you add a new event think about the black box principle. What is the event supposed to do and not how it should be implemented.
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Think abstract. For a TV for example. Don't think "turn on TV", think "Turn on device" where the device is a black box that you don't know what it has inside.
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Information from a device is the same as information from a black box. You will not know what information you get from a device without information about what to expect. The MDF will have that information. You can always get the standard registers.
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Configuration of devices, that is configuration of black boxes, is done by writing registers. If you want to configure a device with events use a decision matrix.