# Presentation: 835516

## What is the VSO?

- (and what isn’t it?)

## The VSO ...

- Allows you to search multiple archives in a single search
- Keeps you from needing to keep track of archives
- Allows for a consistent interface
- Provides data virtualization
- Reduces the time spent searching for data
- Allows scientists to spend more of their time on science

## ... allows you to search multiple archives

- H-alpha Network
- High Altitude Observatory, NCAR
- Montana State University
- National Solar Observatory
- L’Observatoire de Paris
- Owens Valley Radio Observatory
- Solar Data Analysis Center, NASA
- Stanford Helioseismology Archive

## ... keeps you from needing to keep track of archives

- New archives come to you
- Don’t need to bookmark dozens of websites

## ... allows for a consistent interface

- One interface, for all archives

## ... provides data virtualization

- Which is just the IT term for those last three slides

## ... reduces the time spent searching for data

- (okay, technically, this is just derived from the others mentioned before)

## ... allows you to spend more time doing science

- (it’s another derived benefit ... I was bulking up the list, okay?)

## The VSO isn’t ...

- A file retrieval tool
- A specific user interface
- A data archive
- A single system or server
- A file transformation service
- Grid computing, or those other current IT buzzwords

## ... a file retrieval tool

- VSO handles finding and ordering data
- The browser (UI) does the work, like with other search engines.
- Because of the variety in data transfer formats, not all archives provide immediate access
- Eg. Systems where you request the files, and they email you when ready

## ... a specific user interface

- VSO has a default web based interface
- VSO has a published API that allows anyone to write a VSO UI
- EGSO and VSPO use VSO to access data
- Any program that can download a web page can search using VSO

## ... a data archive

- VSO stores no scientifically useful data products
- VSO stores a small description about the holdings of lots of other archives, and uses that information to route requests.

## ... a single system or server

- VSO is a lightweight process, that can be replicated
- VSO has no single point of failure
- There are currently 3 production instances (SDAC, NSO, SHA)
- Future versions of VSO may run as a desktop application

## ... a file transformation service

- Because that’s what CoSEC’s goal is
- CoSEC will be able to find data products using VSO

## ... grid computing

- It uses distributed computing, but each part has a specific purpose
- Grid computing is useful for CoSEC, though

## ... some other marketing buzzword

- We’re a SOAP WebService, sending XML over HTTP, and have WSDL that describes our API
- We’re an OAIS Finding and Ordering Aid

## What VSO Does

- VSO allows you to find new data products based on search criteria
- VSO allows you to order data products from Data Providers.
- Anything else is a function of the specific User Interface
- VSO allows people to write new User Interfaces to build on to the VSO functionality

## How VSO Works ... Finding

- The Solar Physicists (or Equivalent), makes a request through a User Interface
- The User Interface translates the request into terms that VSO can understand, and sends it to a VSO Instance
- The VSO Instance consults its Registry to see which Data Providers may be able to fulfill the request

## How VSO Works ... Finding

- The VSO Instance sends the requests to the Data Providers.
- The Data Providers respond back to the VSO Instance
- The VSO Instance combines the results, and sends it back to the User Interface
- The User Interface formats the results and presents it to the Solar Physicist

## Things that can go wrong

- The Registry is stale
- How often do new Data Providers come online?
- The Registry can’t find any Data Providers to fulfill the query
- That means a really quick ‘no records found’ message
- A Data Provider doesn’t really have the data they claimed to
- The Registry can use a different level of granularity to mark that the data sets are not available

## Things that can go wrong

- A Data Provider isn’t available
- The VSO Instance will give up, and return what it did get back, and a message about the problem provider
- The VSO Instance isn’t available
- User Interfaces can fail over to another VSO Instance
- Too much data is returned
- That’s a problem?
- Use a more specific query

## How VSO Works ... Ordering

- The Solar Physicist selects which data products from their searches that they’d like to retrieve in the User Interface
- The Solar Physicist specifies how they’d like to obtain the data products
- The User Interface sends a request to the VSO Instance

## How VSO Works ... Ordering

- The VSO Instance breaks up the request into parts, and send each part to the correct Data Provider
- The Data Providers act upon the requests, and send a response to the VSO
- VSO combines the results, and sends it back to the User Interface
- The User Interface formats the results and presents it to the Solar Physicist

## Things that can go wrong

- Need to agree on a data transfer method
- Can repeat the request until you agree
- Some Data Providers may require additional information to complete the request
- Can repeat the request with the needed info

## Who is VSO good for?

- Solar Physicists who don’t know what data archives are out there
- or don’t want to know, and only want the data
- Solar Physicists who want to compare data to other instruments than those whose data they normally use
- Confirming anomalies
- Gap filling

## Who is VSO not good for?

- People who are doing work on specific instruments
- They know where the data is, and can most likely access it directly
- People looking for desktop pictures to color coordinate with their current ensemble
- VSO searches for science quality data, although some Data Providers may also provide quicklook images

## How can you help?

- Use VSO
- Try it out, so that you can ...
- Complain
- Let us know what you don’t like
- Give Suggestions
- Let us know what we can do to improve your ability to search for meaningful data
- Let us know which data archives are useful to you

## http://virtualsolar.org/

## Slide 29