[RFC-004]Comment-4

Organization: UAH/ITSC

Review of DAP2 specification

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. You are invited to review the DAP2 Request For Comment (RFC) (see review questions below).

Please send comments before November 12, 2004 to ese–rfc–004@spg.gsfc.nasa.gov

1. (Your background) Describe in a sentence or two your overall implementation experience related to the proposed specification. (e.g., server design; database management; systems architecture; data translation; scientific analysis; science users, etc.)

UAH/ITSC has deployed OPeNDAP servers for data in our data pool and also written and extended new servers to utilize ESML for enhanced support for heterogeneous data formats. Our experience as a data provider, has been that the servers are relatively easy to install, configure and maintain.

1. (Complete) Does the specification provide all the detail you need to implement it in software? (e.g., to write a client, a server, or a format or protocol translator) If not, describe what is missing in the specification.

Yes, from our experience the documentation is complete for server implementation. We have not implemented client packages so can not address that aspect.

1. (Accurate) Do any parts of the specification contain inaccuracies, or internal inconsistencies? If so, please provide details.

No inaccuracies noted.

1. (Clear) Is any part of the specification ambiguous, or poorly explained? If so, please provide details.

No clarity problems with the specification.

1. (Balanced) Does the standard describe the right set of concepts, behavior, data types, and data operations for its intended users? An overly broad set (requiring excessive complexity)? A narrowly simplistic set?

The standard appears concise and appropriate to support implementation.

1. (Useful) How well does this specification meet your information sharing needs? (e.g., Does it work well with the data types and data manipulations in your application? Does it improve on alternative methods, such as file exchange or proprietary software?)

Yes, this specification provides a much-improved method of data access over proprietary solutions as it opens access to a wider choice of current and future data formats for many applications. This approach is still constrained by formats supported by current implementations of client and server components, but improvements can be made on that.

1. (Implementable) What implementation challenges does the proposed standard present? (e.g., Does it require advanced processing power, large amounts of memory, complex configuration, etc.? Does it scale to a production environment?)

We have not experienced scalability problems with the current OPeNDAP implementations and we have used it effectively for large online repositories. The main constraint is typical network inefficiencies of passing large data sets, but this will improve as better bandwidth becomes available across the data community. Data providers who may not have an IT support staff (e.g. some scientific researchers and modelers), may find it daunting to implement and support reliable server functionality. This is typical of data management technologies, however, and should be expected.