Latency requirements determines the degree of user satisfaction about the web service. Software development practices shall consider the end-to-end latency as one of user-oriented characteristics during the entire life-cycle of an application. Latency budget defines latency target and non-functional requirements for distributed systems.
We have learned that resolution of human-friendly names into network addresses is a pre-requirement of any Internet service transaction. Therefore, latency of the DNS infrastructure contributes to the overall user-experience. A slow DNS gives the impression that the service is slow.
The primary goal of TLS/SSL protocol(s) is to provide privacy and data integrity between two communication applications. A full TLS/SSL handshake demands at least two round trips in addition to TCP/IP connection setup.
TCP/IP do not utilizes a full bandwidth when connection is established. It gradually increases a data flow. Effect of TCP/IP slow start and its latency becomes visible for applications while mobile network is used.
Network is a system that make peers to wait. One-way delay shows the network performance from source to destination. Measure the delay and optimise protocols for number of round-trips.
Distributed systems involve various technologies and communication principles that bring overhead and latencies. The root cause of latencies varies from physical properties of the network to the quality of software components. The post discussed sources of latencies from the prism of infrastructure, protocol and application.