I'd like to have a tool that does not actually return anything (is that possible?) but writes a file to the directory where Galaxy stores uploaded data files, and tells Galaxy about it (perhaps that involves writing to a database?). My tool is written in R. Here is my scenario: I want the user to upload a text file, then pass that text file, along with several parameters, (in something we'll call Tool1) which I use to create a serialized R object. That object is then used in several other tools. I don't want the user to have to download and then re-upload the serialized object. I want it to just be available after the user runs Tool1. I realize that workflows could solve my problem here, but I want to keep the UI as simple as possible. For Tool2..ToolN, I don't want to have to always ask the user for the parameters for Tool1 as well as the current tool. So, is there a way for my tool to make Galaxy aware of an additional dataset? Thanks Dan