Services and transactions

Web applications consist of web pages that are served by web servers and web containers, for example Tomcat. Web and mobile applications are built upon services that process requests like web requests, web service calls, and messaging. Such "server-side services" can take the form of web services, web containers, database requests, custom services, and more. Services may in turn call other services such as web services, remote services, and databases services.

Processes are essentially containers that host services. When you look at processes, you're seeing topology information. Whereas services give you code-level insight. For example, you might have a Tomcat process that hosts a web application in the form of a server-side service. While processes are host-centric, associated with a single machine in your environment, services are request-centric and therefore typically span across multiple machines in a data center.