On wireless Grids Information Services have special requirements. Resource information has to be updated when users and resource providers arrive and depart frequently. Meanwhile, Information Services may be also mobile, so the clients and information sources should dynamically detect the existence and departure of Information Services. We present WGMDS, a WSRF-compliant and P2P (peer to peer) based Information Service to meet the special requirements on wireless Grids. We employ P2P mechanism to integrate Information Services to provide Grid-wide resource information. In WGMDS, the clients and information sources dynamically probe nearest Information Services to query or register resource information. Three algorithms are proposed to support the Information Service architecture. We use simulations in NS2 to evaluate the three algorithms.