Testbed Overview

Table of Contents

1. Roles
2. System Components
3. Main Interfaces
4. How does it work?

The SENSEI Pan-European testbed realizes the SENSEI system for integrating heterogeneous sensor networks with the Internet. This section gives an overview of the testbed deployment, its main components and the roles played by various entities involved with the testbed. Finally, a short description about how the testbed works is given.

The figure below shows the deployment architecture of the testbed. The central components of the testbed are deployed on a data center. These components provide services like the resource directory, security along with semantic query interfaces for applications. Embedded devices and sensor networks interact with the SENSEI system using web interfaces for registering and accessing resources. The entity that makes resources on devices or in sensor networks available to SENSEI is called a Resource End Point (REP). Finally, applications can be developed that discover and use these resources. Unlike middleware solutions, SENSEI uses a decoupled approach based on the web architecture. Resources are discovered by making resource directory lookups or semantic queries, but are accessed directly using the resulting URL(s). A management GUI is provided with the central components in order to manage and test the whole system. For more information about the SENSEI architecture, see the ​SENSEI White Paper.

Roles

In the SENSEI project we have identified a large number of technical and business roles played in the machine-to-machine ecosystem. Three of those roles are important when deploying a testbed of the SENSEI system: Resource Providers, System Framework Providers and Resource Users. These are logical roles, and the same entities might play multiple roles. Resource Providers operate the embedded devices and sensor networks used in a SENSEI system. SENSEI Framework Providers host the central components of the SENSEI system, usually located on one or more well-known servers. This Cookbook is organized by these roles played in the system.

• TODO: Figure showing roles

System Components

The SENSEI system is made up of loosely coupled components which can be categorized by their purpose. Framework Components are hosted by System Framework Providers, and they provide the core functionality of the SENSEI architecture. Community Management Components provide security, authentication, privacy and billing functionality, usually also hosted by System Framework Providers. Resource Interaction Components are used by Resource Providers for making devices and sensor neworks available to the SENSEI system, and by Resource Users for interacting with the SENSEI system.

The main Framework Components include:

• Resource Directory - The Resource Directory acts as the repository about all the resources available in a SENSEI domain. It accepts resource publications over the Resource Publication Interface (RPI) from REPs, and can be queried by Resource Users and other components over the Resource Lookup Interface (RLI). Resource directories between different SENSEI domains can also be peered.

• Semantic Quert Resolver - The Semantic Query Resolver provides a higher level interface to the SENSEI system by supporting the search for resources semantically. This is achieved using either simple or language-based queries over the Semantic Query Interface (SQI).

• Entity Directory - The Entity Directory holds context information about resources, complimenting the Resource Directory. Entity context information is either entered in the ED manually, or built-up automatically each time a REP includes an advanced research description when publishing to the RD.

• Execution Manager - Rather than simply accessing single resources, the Execution Manager provides a way to specify execution plans, which describe a sequence of resource access or actuation steps.

The main Comminity Management Components include:

• AAA - The SENSEI AAA component provides access control for the entire SENSEI system. This includes both a security token service for providing identities, and a AAA service against which REPs and other components check access control rights for requesting resources. A section on REP access control is also provided, describing how to use AAA from a REP.

• Privacy and Billing - The Privacy and Billing component provides and alternative approach to the access control provided by the AAA component. A security token installed in the resource user (a Firefox pliug-in is also provided) is used to authenticate a resource user. In addition, an accounting service is provided, allowing access to be denied also due to insufficient funds.

• TODO: Figure showing server components

The main Resource Interaction Components include:

• Resource End Points - A Resource End Point (REP) is any implementation of SENSEI RAI interfaces accessible via a URL described in the Resource Directory. Several different REP implementations are provided by SENSEI. The Java REP Framework is an extisible Java SE implementation of SENSEI interfaces.

• Gateways - In order to expose resources hosted in embedded sensor networks, entities called gateways are used to provide those resources as SENSEI REPs (thus implementing the RPI and RAI interfaces). In a native SENSEI island the sensor nodes also support IP, but realize a subset of the SENSEI interfaces with the Constrained Application Protocol (CoAP). The Native SENSEI Gateway proxies these resources to the rest of the SENSEI system. A ZigBee Gateway has also been provided to expose ZigBee? nodes in an island to the SENSEI system.

• Embedded REPs - Two different embedded REP implementations, compatible with the Native Gateway, have been realized. The Contiki REP provides an implementation of the embedded REP for the popular Contiki embedded operating system. The TinyOS REP provides an realization of the embedded REP for the popular TinyOS on a TelosB compatible hardware platform.

• Management GUI -

Main Interfaces

• Common Interfaces
  1. RPI
  2. RLI
  3. RAI
  4. SQI

• Section on other advanced interfaces

How does it work?

• How does the testbed work?