Electronic Product Code Discovery Service (EPCDS) is an important concept in supply chain processes and in Internet of Things (IOT). It allows supply chain participants to search for their partners, communicate with them and share product information using standardized interfaces securely. Many researchers have been proposing different EPCDS models, considering different requirements. In this paper, the authors describe existing architecture designs of EPCDS systems, namely Directory Service Model, Query Relay Model and Aggregating Discovery Service Model (ADS). They also briefly mention Secure Discovery Service (SecDS) Model, which is an improved version of Directory Service Model with a secure attribute-based access control mechanism.