A management of WWW server is still relying on the expertise and heuristic of administrators, because the comprehensive understandings of server behavior are missing. The administrators should maintain the WWW server with good states that they should investigate the WWW server in real time. Therefore, it is exactly desirable to provide a measurement application that enables the WWW server administrators to monitor WWW servers in the actual operational environment. We developed a measurement application called ENMA (Enhanced Network Measurement Agent) which is specially designed for WWW server state analysis. Furthermore, we applied this application to the large scale WWW server operation to show its implementation and advantages. In this paper, we analyze the WWW server states based on precise monitoring of performance indices of WWW system to help the server management.

While Electro-Optic (E-O) sampling has achived the electric signal measurement with advantages of noninvasive, noncontact and ultrafast time resolution, it is unsuitable for measuring long logic patterns in fast ICs under the functional test conditions. To overcome this problem, a real time E-O probing using a continuous wave (CW) diode laser and a fast photodetector has been developed. By adopting a ZnTe E-O probe having a half-wave voltage of 3.6 kV, shot noise limited measurement with a frequency bandwidth of 480 MHz has been achieved using a low noise diode laser (wavelength of 780 nm, output power of 30 mW), a pin photodiode, a wideband low noise amplifier, and a digital oscilloscope having 500 MHz bandwidth as a waveform analyzer. The minimum detectable voltage was 23 mV under 700 times integration. In this paper, discussion of the voltage sensitivity of real time E-O probing is included. Key parameters for attaining the highly sensitive real time E-O probing are the sensitivity of the E-O probe and noises of the probing light and detection system.