The use of Internet Protocol (IP) technology in Wireless Sensor Network (WSN) is a key prerequisite for the realization of the Internet of Things (IoT) vision. The IPv6 over Low power Wireless Personal Area Networks (6LoWPAN) standard enables the use of IPv6 in networks of constrained devices. 6LowPAN enables the use of Service Oriented Architectures (SOAs) in WSN. The Internet Engineering Task Force (IETF) has defined the Constrained Application Protocol (CoAP), a web transfer protocol which provides several Hypertext Transfer Protocol (HTTP) functionalities, re-designed for constrained embedded devices. CoAP allows WSN applications to be built on top of Representational State Transfer (REST) architectures. This considerably eases the IoT application development and facilitates the integration of constrained devices with the Web. This work describes the prototype design and development of a Web platform which integrates a REST/CoAP WSN with a REST/HTTP Web application and allows a user to visualize WSN measurements in the Web browser. Since the WSN Web integration relies on a non-transparent gateway/server, we also show how to provide transparent cross-protocol resource access by means of an HTTP-CoAP proxy. The paper describes the major building blocks, functionalities and the implementation approach.