I'm developing a web application that aims to manage inventory, sales projections, etc. of a company. However, sellers travel to make sales and have requested that they also make an application that communicates with DB. To do this, I need to be able to access the web application database through the mobile phone while I handle the possible conflicts and temporarily save sales made in case there is no internet connection until it becomes available. Could someone give me a bibliography or some project that uses these resources?