[RFC 004] Operation Review Comment 6

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. 

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).

The overall experience with OPeNDAP has been very successful.�� The GDAAC is using OPeNDAP HDF, OPeNDAP Freeform, Ferret, GrADS and GDS.

1. How long have you been using DAP2 operationally?

�� �������� GDAAC has been using OPeNDAP since March 2001.

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?)��

GDAAC mainly uses the DAP system in OPeNDAP to serve V0 and datapool data.

3. Why do you choose to use DAP2 systems over other systems for your applications?

GDAAC selected OPeNDAP because of it�s capabilities :

1)     serve data in different formats

2)     handle small subset over the internet

3)     open source

4)     large scientific user communities

4. Are the DAP2 systems easy to use?� (e.g., Is it hard to learn how to use DAP2 systems?)

OPeNDAP is easy to install and customer support is excellent.

5. 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?)

There were some problem with OPeNDAP opening large MODIS files; however this problem has been resolved with newer version.� Like with most servers, the larger the files the longer the access time.

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?)

GDAAC has not noticed any decreased in our bandwidth.

6. 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?)

Nothing that the GDAAC can�t handle.

1. How has the use of DAP2 affected your systems administration workload?

None

7. How well do the DAP2 systems scale to large numbers of simultaneous users, or to large datasets?

Although the GDAAC do not keep track of how many simultaneous users accessing our system, we do keep track of the monthly access.

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

We don�t have all the stat but here are some stats from last year.

8. 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

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