1. A computer-implemented method for displaying service operations in a service-oriented architecture (“SOA”) environment, comprising: determining, for a plurality of service operations comprising an SOA solution in the SOA environment, each selected one of the plurality of service operations for which at least one observed instance thereof has been executed; creating, for each of the selected service operations, a single node to represent all of the executed observed instances of the service operation and storing, in association with the single node, an aggregation of information from all of the executed observed instances of the service operation, wherein: at least one particular one of the created nodes represents one of the selected service operations for which at least two observed instances have been executed; and at least one of the at least one particular one of the created nodes represents a service operation for which the observed instances executed at different application servers in the SOA environment; determining each of a plurality of calls that occurred between the executed observed instances, each of the calls comprising a calling one of the selected service operations and a called one of the selected service operations; creating, for each distinct combination of calling one and called one in the determined calls, a single link to represent the distinct combination and storing, in association with the single link, an aggregation of information from all of the determined calls that occurred between the calling one and the called one; and displaying on a user interface, using the created nodes and links, at least one call relationship among the selected service operations, wherein: each displayed call relationship comprises a graphical representation corresponding to a first one of the created nodes and a second one of the created nodes and a link therebetween, the link therebetween corresponding to the single one of the links that represents the distinct combination in which the calling one comprises a first of the selected service operations which is represented by the first one of the created nodes and in which the called one comprises a second of the selected service operations which is represented by the second one of the created nodes and, in a recursive manner, a graphical representation corresponding to additional ones of the created nodes and links therebetween, the links therebetween corresponding to any ones of the single links that represent the distinct combination in which either the called one or the calling one comprises either the first or the second of the selected service operations; the graphical representation corresponding to each of the created nodes is selectable from the user interface and further comprising, responsive to selecting one of the selectable graphical representations, displaying a drill-down view comprising a graphical representation of each of the observed instances of the service operation represented by the corresponding node; and the drill-down view further comprises, for at least one of the graphical links between the graphical representation of the corresponding node and the graphical representation of a different one of the nodes, a graphical representation of each of the observed instances of the service operation represented by the different node and a graphical representation of links between calling and called ones of the observed instances of the service operation represented by the corresponding node and the observed instances of the service operation represented by the different one of the nodes.