For example, when multiple instances of services A and B call multiple instances of service C, the combination of deep monitoring of service C instances and outbound monitoring of instances of services A and B gives us a beautiful picture. We can better locate important traffic sources and objectives and identify noisy neighbors, routing issues, or slow instances. When a product is a network of interconnected services with a rich collection of external dependencies, it is really difficult to identify bottlenecks or faulty services. A single system-long model is too complex to define and understand. For the API, an API contract or API description has been defined, including the functional specification of the interface (i.e. requirement and response messages with parameters) of the operations. The dynamic behavior of API operations during the call is not yet clearly expressed with regard to their qualitative and quantitative characteristics of QoS quality of service. .