Very Large scale telescopes and virtual observatories have in common to be global facilities, which will enable entirely new types of sciences and will require new technical and operational philosophies. Joint discussion 8 was built with a series of invited reviews to set the long term vision and challenges, and specific projects or technical topics were presented in the poster session which was also a very important part of the meeting. To keep track of all the contributions, these proceedings contain the abstracts of all papers, invited reviews and accepted contributed posters, with a few extended abstracts.