A general model of an E-business system comprising an Application Server and a Database engine is analyzed and evaluated. Incoming jobs, once admitted for processing, compete for the available resources. Database accesses are of different types and are subject to time-outs. An efficient approximate solution is provided; its accuracy is evaluated by comparing the model estimates with those obtained from simulations. The effect of several controllable parameters on the performance of the system is examined in a series of numerical and simulation experiments.