With the development of Internet of Things (IoT), bridging wireless sensor netw orks (WSNs) with other netw orks has become importan t. We divide bridging sol utions into tw o categ ories: the hardw are sol utions and the middlew are sol utions. The hardw are sol utions have both low pow er short distance wireless interf aces and other types of transmission interf aces, e.g. GPRS, 3G/4G, via hardw are implemen tations, which is more stable and applicable for the depl oyed sensor netw orks. In the middlew are sol utions, the whole system processes appropria te protocol conversion, and independence of hardw are, making it easier to be reused in di fferen t applica tions and netw orks. This paper brief y presen ts the implemen tation details and key poin ts of each solution. Particularly, we deriv e the most appropria te situa tion for each solution from our comparisons and discussions in terms of ev al ua tion applied to di fferen t criteria.