As you might know, many of us are meeting next week in Baltimore (physically and virtually) to discuss portal development in Year 2 (which we plan to dive into right after the second beta release of the Data Discovery Tool at the end of September). This meeting is part of an effort across all our science initiatives to ensure that our development is science-driven. Consequently, the big focus of this meeting will be science use cases. Gretchen Greene has assembled a great set of use cases that were developed by a number of people reaching back to the NVO days and spanning to more recent examples from the VAO and the IVOA. This week I spent some time with these use cases to try to pull out some common features and needs. It was an inspiring and worthwhile exercise--I highly recommend it.
Doug Tody made the comment this week that considering these use cases as they are laid out on that page makes this meeting more of one about the VAO architecture. I believe he was making reference to the fact that our first year's effort for the portal was about data discovery, resulting in a nicely focused tool that includes some new techniques for quickly finding and selecting datasets. The use cases, on the other hand, go beyond discovery. So, yes, I have to agree with him: addressing these use cases does mean addressing the VAO architecture.He also said in the same breath, "I'm not sure what the Portal is." As we take a step back to consider what we've accomplished in the first year and what we'll aim for in the second, it's a good time to try re-answering that question. We should do it in terms of science use cases--what it is we want astronomers to accomplish--and, yes, this means addressing some of the essentials of the VAO architecture.
I want to suggest that we see the Portal as a web-based entryway to a collection of tools that work together. What you can do in the portal goes beyond data discovery; that is, the Data Discovery Tool is just one of those tools. The Cross Comparison Tool should be another (actually quite a critical one, as I hope to discuss in a later post). The TAP client should have a presence there as well. And what can you accomplish in the portal? Those use cases, of course.
Updated 9/6: Given the discussion below, I should note that I meant to say that the Portal--in my definition--is explicitly browser-based (with programmatic web service interfaces possible, too).
In this vision, the Portal is not a monolithic tool that does everything; each tool specializes in some task, and over time we can add more tools. It's worth noting though that like all good use cases, ours say nothing about "tools." Clearly, to solve those problems, one will have to use several tools together. Thus, a key aim of the Portal is allowing the tools to work together: the user should be able to easily discover and create lists of datasets and sources with the Discovery Tool and join them together with the Cross-Comparison Tool. It would be great if that collaboration of tools were so quick and smooth, that the user may not realize that two different tools were used. Of course, this kind of collaboration extends to the desktop: the user should be able to send selected catalog records to Topcat and a list of SEDs to Iris.
A key question, then, we need to answer in the design of the Portal is what is needed to allow these tools to work together? This, some of you will recall, was a key problem that had to be tackled when we were developing the NVO portal. Fortunately, we have a few more technological options available to us today than we had back then.
The other key question that comes out of this vision is what tools do we need to put into the Portal? To answer this, we need to look carefully at the use cases. I would like to see us break down each of these into a sequence of scientific steps. Then we can ask, which of these tasks can be answered with the Discovery Tool? Where can we call in the Cross-Comparison Tool? And more importantly, what tools are missing? We're also likely to discover that our current tools are not quite tuned to these tasks and need some adjusting.
Actually, having gone through these use cases once, dissecting them can be a bit challenging (but interesting). I did glean, I think, some important and common features that we need to support which I hope to share in my next post. Next week, we'll get more eyes on these use cases, and I hope we can pick out a few exemplary ones which we will use to guide further portal development. So what is the Portal, or rather, what will it become? Ultimately, it is--and I know this is cheap to say--a place to do science. We need to be able tell users what science they can do with the portal; we should be able to describe at least a few of these use cases and have it sound compelling and useful to them.
