Yeah, I was using Novell DirXML to do XSLT processing of inbound/outbound data in 2000 (https://support.novell.com/techcenter/articles/ana20000701.h...) for directory services stuff. It was full XML body (albeit small document sizes, as they were usually user or identity style manifests from HR systems), no streaming as we know it today.
But they worked on the xml body as a whole, in memory, which is where all the headaches started. Then we introduced WSDLs on top, and then we figured out streaming.