Motivated by the importance of metadata for WoT systems, in this paper, we describe building a metadata management system which is scalable and rich in semantics. We describe two implementation approaches and discuss advantages and disadvantages of each: the embedded approach and the middleware approach. We also identify three components relevant to managing the metadata: the storage, the representation and the access. Based on our experience with implementation, we conclude that: (i) both the embedded and the middleware solutions can already be prototyped, but some critical technologies for the embedded approach are still in early development and require considerable improvements, (ii) XML like syntax is not well suited for storing and transmission of metadata due to sensor device constraints with respect to available storage and link datarate; and (iii) the middleware approach proved more convenient from the web application developer's point of view.