We present in this paper a system for the management of geographic databases from mobile devices. The architecture of the system is extensible in the sense that it can be adapted to the particular characteristics of a wide variety of heterogenous mobile devices. This is achieved by the incorporation of an extensible middleware between the limited GIS applications running at the Mobile devices and the general purpose web services used at the data tier. The interfaces of these web services are compliant with the well-known Web Map Service(WMS) and Web Feature Service (WFS) specifications proposed by the Open Geospatial Consortium (OGC). A first prototype of the system for a specific PDA hardware with a specific software configuration was also implemented. We believe that the system has many practical applications in wireless environments with connectivity problems.