Changes between Initial Version and Version 1 of VsoFAQ2

06/10/05 13:05:20 (17 years ago)



  • VsoFAQ2

    v1 v1  
     1= Infrequently Asked Questions = 
     3== (and known bugs/problems) == 
     5You may also want to take a look at the [wiki:VsoFAQ Frequently Asked Questions] list. 
     8== Questions == 
     11=== How do I file a problem report or suggestion for improvement? === 
     15We suggest you use 
     16our general feedback form  
     18or email your reports/comments/suggestions to: 
     19''''.  You can also fill out our 
     20'''[ user survey]''' so we can 
     21prioritize based on the needs of the user community. 
     23You should also check that you are using the most recent version 
     24of VSO.  The most recent link will always be available from the VSO homepage 
     25at ''''''. 
     27=== I have a digital data archive and I would like to make the data available through VSO.  What do I have to do? === 
     29Please contact one of the VSO scientists (Rick Bogart, Joe Gurman, Frank Hill, 
     30Piet Martens) and let us know of your interest.  Extension of data service 
     31providers is the highest priority for VSO.  We have an adoptor's kit, and 
     32assistance available to help tie your archive into VSO. 
     34The majority of the work from the provider is in attempting to describe 
     35your holdings in terms of the VSO Data Model, so that the VSO has 
     36accurate information about the type of information that your organization 
     39=== Are there limits to the number of query results returned?  If so, what are they? === 
     41Yes.  Each data provider may have limits to prevent their systems 
     42from returning exceptionally large results.  Because of the way in which 
     43VSO breaks queries down into simpler queries for the individual data 
     44providers to process, it is difficult to say just how many records an 
     45individual data provider will return. 
     47=== How do I know if the number of query results was truncated by the data server? === 
     49The results page lists two numbers -- the number of records returned, and the 
     50number of records found.  If the two are not equal, it means that one the 
     51data providers has reached its internal limit, and not returned all of its 
     52records that matched the query.  If the number of records found is not displayed, 
     53it suggests that the data provider had reached its limit, but did not determine 
     54how many additional records there were.  [This should only occur if the cost in 
     55performing an exhaustive search would be prohibitive]. 
     57We are trying to find a good balance between obtaining the desired results, 
     58while preventing there from being an undue burden on individual data archives, 
     59and the mechanisms for handling this scenario may be changed in the future. 
     61=== When I request data, do they have to go through the VSO?  How long does it take to get the data? === 
     63No data go through VSO.  VSO only handles the process of locating, and ordering 
     64the data.  The actual data delivery is handled by the user and the individual 
     65data providers, although it is possible that some user interfaces may add 
     66additional value by automatically following URLs to download information. 
     67For more information about the transfer of data, see the 
     68'''[ API documentation on Transfer Negotiation]'''.  Additional information is available 
     69for the '''[ data providers]''', but 
     70is currently in the process of being updated. 
     72=== When I submit a query, at the end of the list of results it says Session ID: followed by a long incomprehensible hexadecimal string.  What does it mean? ===  
     74You may be using an older version of VSO.  Please make sure you are 
     75connecting to the most recent 
     76'''[ VSO Search Interface]'''.  We are experimenting with mechanisms for recording 
     77search parameters and/or results (at the option of the user), so that 
     78any particular 
     79useful query can automatically be regenerated if desired, or referred to 
     80in publication of results. 
     84=== All queries seem to go through and require the (''some organization'') VSO site.  What is virtual about the Virtual Solar Observatory? === 
     86There originally was a single prototype implementation at Stanford.  That has 
     87since been replaced with a system that is distributed across Stanford, NASA, 
     88and NSO, not including the functionality at each of the individual data 
     91What is virtual about VSO is that there is no one master archive or 
     92database of all of the holdings.  There is a point of entry that users 
     93or applications can interact with, to access data that is spread across multiple 
     94systems.  This concept is commonly refered to as 'Data Virtualization'.  Additionally, 
     95there is virtualization on another scale, as there is no one single server -- 
     96Although there is a reference system, at 
     97'''''', its  
     98purpose is to provide a unified starting point to people new to the VSO, 
     99and is not involved with the actual processing of the VSO, which currently  
     100has multiplexors at SDAC, Stanford, and NSO. 
     102=== The information in the server data registries does not always match what is actually searchable.  Are the displayed data registries different from those used by the user interface? === 
     104Please '''[wiki:ContactUs send us details]''' 
     105about what you have found that doesn't seem to be in agreement, or  
     106what query you used, that you had expected data to be returned for. 
     108=== What do all the funny colors on the results pages mean? === 
     110For ease of navigating among large numbers of return results, every 
     111fifth entry from each data provider is highlighted in yellow, every 
     112tenth in green, and every hundredth in blue.  No special significance 
     113attaches to these entries. 
     116== Problems == 
     118=== When I query data from the (Montana State University|Mauna Loa) archive, I get lists in which apparently identical data sets are reproduced from two to seven times.  When I download these data sets, they are indeed identical. === 
     120Observations in the MSU Yohkoh SXT archive are catalogued individually but packaged 
     121together in orbit files.  If several observations in the same file match 
     122the search criterion they will each return a record, but the records will 
     123all point to the same distribution file.  Downloading any one will of course 
     124get you all the data in the orbit file. 
     126Observations in the MLSO archive are stored in both JPEG and FITS formats. 
     127Although the observations occur in the listings twice, they point to 
     128different data products.  It is possible that this may change in the future, 
     129depending on user feedback. #13 
     131=== I don't see any data from the McMath FTS Spectrometer, though it shows up in the NSO list of instruments. === 
     133The VSO has helped us to shed light on the fact that some metadata 
     134are not correct.  In this particular case, most of the datasets listed 
     135from the Kitt Peak 512-Channel Magnetograph 
     136and from the Evans Spectroheliograph have end times earlier than the start 
     137times.  Occasionally there are multiple entries that are apparently identical 
     138(e.g. KPVT Magnetograph 1993.04.10). 
     140=== I don't see any data for the last day of my time range request from the GOLF instrument, even though I know it is there; it shows up if I extend the range of time by even one minute. === 
     142Please make sure you are using the most recent version of VSO.  Early versions 
     143of VSO required the observation to be completely contained within the search 
     144range.  The current implementation performs range matching by searching for  
     145non-vanishing intersection. 
     148=== When I query the Stanford Heleioseismology Archive for ground-based data I sometimes see records whose start and end times are both outside my requested time interval. === 
     150Range matches (in this case, time range), is done by finding a non-vanishing 
     151intersection.  If you would prefer a different type of range matching, please 
     152'''[wiki:ContactUs let us know]''', so we can 
     153prioritize new functionality. 
     155The Stanford datasets are generally for sets of images spanning a long 
     156time interval, typically a day for ground-based instruments.  Although 
     157the datasets have registered start and end times corresponding to the 
     158first and last images of the day, they are in fact searched by an index 
     159number corresponding to the day number, starting at local midnight. 
     160In order to assure that no relevant records are missed from sites whose 
     161observations can span two UT days, the Stanford server returns matches 
     162for both day numbers.