The OpenIoT Approach to Sensor Mobility with Quality-Driven Data Acquisition Management - Interoperability and Open-Source Solutions for the Internet of Things - page 48

Fig. 1. High-level OpenIoT publish/subscribe architecture

as Linked Sensor Middleware (LSM-Light) integrates an RDF store to be used
as the OpenIoT Cloud Database.
A Mobile Broker and the CPSP Engine running within the OpenIoT cloud
interact over a publish/subscribe interface Q p . The CPSP Engine and the QoS

Manager also interact over the same interface

Q p by use of the following mes-
sages: publish , subscribe , notify and announce . In addition, the QoS Manager
exposes a web service interface Q w through which it offers services to other

OpenIoT components. For example, if a user of the OpenIoT platform wants
to locate available mobile data sources in his/her close vicinity, or average data
readings acquired by mobile sensors for a specific area, he/she can access this
information through the

Q w interface. Both interfaces are explained in more

detail in Sects. 3 and 4 .

2.1 Cloud-Based Publish/Subscribe Middleware (CUPUS)

CUPUS implements the standard publish - subscribe - notify communication pat-
tern enhanced with an announce message to advertise the data types associated
with mobile sensors and sensor locations. It has a hierarchical three-tier archi-
tecture with the CPSP Engine at the top layer, MBs running on mobile devices
at the middle layer, and publishers and subscribers at the bottom layer. Pub-
lishers and subscribers typically also run on mobile devices and can also connect
directly to the CPSP Engine. For example, a mobile device with attached sensors
acts as both a data source (publisher) and data destination (subscriber) since
device users can define continuous requests for data in the form of subscriptions.