1. A system for generating application-level dependencies in one or more virtual machines (VMs), comprising: an application performance management (APM) server running on a physical machine, wherein said APM server accepts a request and sends a control command to at least one forward daemon, each of said at least one forward daemon transfers the control command to a corresponding VM manager to turn on at least one inspecting status of at least one VM of said one or more VMs, and said APM server further generates an application trajectory of a selected application and exports application-level dependencies from the application trajectory for said selected application; one or more intercepting modules, wherein each intercepting module intercepts a guest operating system (OS) at transmission control protocol (TCP) send and closely-related operations on the at least one related VM; and one or more introspecting modules, wherein each introspecting module performs VM introspection for TCP connection and running thread information; wherein each intercepting module intercepts either by hardware breakpoint at thread-level or by intercepting TCP-related system calls; wherein a decision to select an intercept mechanism depends on a number of hardware debug registers supported by a central processing unit (CPU) and a number of TCP send and closely-related functions; and wherein when the number of hardware debug registers supported by a CPU is greater than the number of TCP send and closely-related functions, intercepting by hardware breakpoint is selected as the intercept mechanism.