It sounds like you want to create a workflow which is capable of downloading some data from a URL, and you also want to be able to trigger that workflow remotely from some other service or application. Is that correct?
If so, then yes KNIME Server can be used for this. With KNIME Server Medium or Large you can host KNIME workflows as REST APIs. You could upload a workflow (which executes the data downloading steps) to KNIME Server and then call that workflow via REST from another service or application. See KNIME Server Pricing for more details on the features we offer per tier for KNIME Server.
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