A method, performed at a client system, for monitoring of user interactions between a user at the client system and a back-end system, the method comprising: capturing primary semantic information in the form of user-activity-related data regarding a primary user interaction with the client system, the primary user interaction causing a primary request to be sent to the back-end system; sending the primary request to the back-end system, the primary request having a user-activity-monitoring parameter used to include at least some of said primary semantic information and to pass said information about the primary user interaction from the client system to the back-end system; receiving at the client system a response from the back-end system including a primary context identifier generated at the back-end system for linking at least some of the primary semantic information with one or more operations performed by the back-end system in processing the request; characterised by: capturing secondary semantic information in the form of further user-activity-related data regarding the primary user interaction and capturing secondary semantic information in the form of further user-activity-related data regarding a secondary user interaction with the client system, the secondary user interaction causing a secondary request to be sent to the back-end system; sending the secondary request to the back-end system, the secondary request having a user-activity-monitoring parameter used to include at least some of said secondary semantic information regarding the primary user interaction and said primary context identifier and to pass said information about the primary and secondary user interaction from the client system to the back-end system; and receiving at the client system a secondary response from the back-end system including a secondary context identifier generated at the back-end system for linking at least some of the secondary semantic information with one or more operations performed by the back-end system in processing the secondary request. capturing primary semantic information in the form of user-activity-related data regarding a primary user interaction with the client system, the primary user interaction causing a primary request to be sent to the back-end system; sending the primary request to the back-end system, the primary request having a user-activity-monitoring parameter used to include at least some of said primary semantic information and to pass said information about the primary user interaction from the client system to the back-end system; receiving at the client system a response from the back-end system including a primary context identifier generated at the back-end system for linking at least some of the primary semantic information with one or more operations performed by the back-end system in processing the request; characterised by: capturing secondary semantic information in the form of further user-activity-related data regarding the primary user interaction and capturing secondary semantic information in the form of further user-activity-related data regarding a secondary user interaction with the client system, the secondary user interaction causing a secondary request to be sent to the back-end system; sending the secondary request to the back-end system, the secondary request having a user-activity-monitoring parameter used to include at least some of said secondary semantic information regarding the primary user interaction and said primary context identifier and to pass said information about the primary and secondary user interaction from the client system to the back-end system; and receiving at the client system a secondary response from the back-end system including a secondary context identifier generated at the back-end system for linking at least some of the secondary semantic information with one or more operations performed by the back-end system in processing the secondary request. capturing secondary semantic information in the form of further user-activity-related data regarding the primary user interaction and capturing secondary semantic information in the form of further user-activity-related data regarding a secondary user interaction with the client system, the secondary user interaction causing a secondary request to be sent to the back-end system; sending the secondary request to the back-end system, the secondary request having a user-activity-monitoring parameter used to include at least some of said secondary semantic information regarding the primary user interaction and said primary context identifier and to pass said information about the primary and secondary user interaction from the client system to the back-end system; and receiving at the client system a secondary response from the back-end system including a secondary context identifier generated at the back-end system for linking at least some of the secondary semantic information with one or more operations performed by the back-end system in processing the secondary request.