Operational Paradigm

A. Basic Operational Paradigm of a Network Sensor

A Network Sensor can be described as an X3D Node that can be used in X3D scenes to achieve network connectivity for following Use Cases:

A.1. The Maintenance Use Cases

1.a. Initialize and authorize the NetConnection, keep it alive

1.b. Load, initialize, purge and unload avatars

1.c. Initialize static NSNs

1.d. Load, initialize, purge and unload dynamic models with embedded NSNs

1.z. and so on

A.2. The Common Use Cases

2.a. Movement of initialized avatars

2.b. Gestures of avatars (w. or w./o. body tracking)

2.c. Chat, Voice Chat (both could be realized outside of the X3D scene or inside)

2.z. and so on

A.3. The Model Specific Use Cases

3.a. Event Distribution

3.b. Persistent Storage and Distribution of State

3.c. Simple Server Side Calculations

3.d. Customized Client Side Calculations

3.z. and so on

Please refer to This Slideset for details.

B. Example Scene Using a Network Sensor

The following figure explains the parts of an example scene containing just one model and nothing else. The model contains a Network Sensor in turn.

B.1. Common Interface (Example)

The scene author (blue) has retrieved a model from a model author (green) and must now connect the model with the Network Sensor Infrastructure.

Therefore he uses the CNSI (Common Network Sensor Interface) - e.g. with some fields like SFNode connection, SFString streamName or SFString sensorId - and the NSII (Network Sensor Infrastructure Interface) - e.g. with some fields like MFString tryLogin, MFNode addAvatar or SFInt32 sessionIdLeft - in order to implement the Maintenance Use Cases (see section A.1.) and the Common Use Cases (see section A.2.).

B.2. Specific Interface (Example)

The SNSI (Specific Network Sensor Interface) should - in this case - be handled completely within the model and by employing the HNSI (Hidden Network Sensor Interface), handling the Model Specific Use Cases described in section A.3.

The scene author (blue) is not interested to know all the details of the SNSI the model author (green) is involved with.

C. Conclusions from the Example (to be consolidated)

1. Every Network Sensor implementation MUST employ a HNSI to connect the Network Sensors with the Network Sensor Infrastructure (in particular with the Network Connection(s)) for the Model Specific Use Cases
2. The HNSI MUST be invisible outside the Network Sensor and the Network Sensor Infrastructure
3. A Model Author MAY "bury" Network Sensors within his Model, which implies the SNSI and the HNSI are not affecting the "master scene"
4. Every Network Sensor implementation MAY provide a CNSI that MUST then be forwarded by the model author and by the scene author to the "Scene Controller"
5. Every Network Sensor implementation MUST provide a NSII that can be used by the "Scene Controller" for Maintenance Use Cases and for Common Use Cases.