A plurality of equipment connected to a network are linked with each other to perform plural processing operations to document data. When, for example, a user defines a desired service linkage job flow by using, for example, a GUI screen displayed on a client terminal, job flow information is transmitted to a script creation server, and a script is created in which processing contents and a storage location of a document as a processing object are defined. The created script can be stored in a storage unit such as, for example, a script management server. When the user selects a desired script among plural scripts stored in the script management server, the selected script is transmitted to a linkage processing server. The linkage processing server interprets the script, makes a processing request to respective devices such as, for example, an image processing device so that the document is processed in accordance with the processing contents described in the script, and links the devices with each other to perform plural processing operations.