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[RFC 004] Operation Review Comment 1 Printer-friendly version Add This

Review of DAP2 operational experience:

 

NASA's Earth Science Data Systems Standards Process Group (SPG) is considering the Data Access Protocol, Version 2, (DAP2) for adoption as a community standard.  This is the second review of DAP2, this one focusing on its operation experience. The questions below are provided to guide your feedback. You only need to answer questions applicable to you.  Please send comments to eserfc004@spg.gsfc.nasa.gov.

 

 

  1. Describe in a sentence or two your overall operational experience related to DAP2 (e.g., scientific analysis; science users, server operation; database management; or data translation, etc). What kinds of DAP2 systems do you have experience with? (e.g., OPeNDAP netCDF server, OPeNDAP HDF server, OPeNDAP Matlab Toolkit, Ferret, GrADS, and etc).

 

I work in Collection Localisation Satellite (http://www.cls.fr/welcome_en.html) in the Spatial Oceanographic Department. Im in charge of the distribution of the data produced in CLS. Two types of data : altimetry data from SSALTO/DUACS project, and oceanographic model data from Mercator

(http://www.mercator-ocean.fr/html/mod_actu/public/welcome_en.php3). I also work on the MERSEA project (www.mersea.eu.org) for the distribution of the data.

We choused Opendap technology for the web distribution of our data (netCDF data), plus the simple ftp. In this technology, we choused the Aggregation Server. The operational phase has begun 2 years ago.

 

    1. How long have you been using DAP2 operationally?
  2. What types of applications do you use DAP2 systems for? Are the DAP2 systems applicable to your applications? (e.g., Do they work well with the data types and data manipulations in your application?)

 

Yes, it works well.

    1. How many of your applications use DAP2?

                                                               i.      Total number of applications

                                                             ii.      Percentage of applications

  1. Why do you choose to use DAP2 systems over other systems for your applications?
    1. What alternative technologies did you consider?
  2. Are the DAP2 systems easy to use? (e.g., Is it hard to learn how to use DAP2 systems?)
    1. How has the use of DAP2 affected your user support workload?
  3. Does the performance of the DAP2 systems you have experienced meet your requirements? (e.g., Does it take a long time to access data in DAP2 systems?)

 

The old version of the Aggregation server worked well, but we have a lot of problem with the new thredds aggregation server (bad performance, java.lang.outOfMemoryError, crash of the system)

    1. Have your bandwidth issues changed since you have been using DAP2 systems? (e.g., Have you seen increased bandwidth requirements because of increased data access or DAP2 overhead, decreased bandwidth requirements because of reduced data volume from subsetting, no impact on bandwidth because of low usage?)
  2. What operational challenges do the DAP2 systems present? (e.g., Does it require advanced processing power, large amounts of memory, complex configuration, etc.? Are the systems easy to deploy and maintain?)
    1. How has the use of DAP2 affected your systems administration workload?
  3. How well do the DAP2 systems scale to large numbers of simultaneous users, or to large datasets?

1 To, it is the biggest data volume served in an Opendap here (Mercator ocean model data in netCDF).

The AVISO Opendap (http://opendap.aviso.oceanobs.com) serve 300 Go.

 

    1. How much data does your DAP2 system handle in a typical month?

                                                               i.      Total data volume

                                                             ii.      Total number of data files

                                                            iii.      Percentage of data volume

                                                           iv.      Percentage of data files

  1. Can you provide information on user statistics of your DAP2 systems?
    1. How many users does your DAP2 system handle in a typical month?

                                                               i.      Total number of DAP2 users

                                                             ii.      Percentage of your overall users

    1. Of the feedback you have received from your users on DAP2, what percentage is positive and what is negative?
    2. How have the user statistics changed over time?