[RFC-004]Comment-5

Organization: San Diego Super Computer Center

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. The following is my review for the DAP2 Request For Comment (RFC) (in responding to the review questions).

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.)

The Storage Resource Broker (SRB) is a data grid that manages data distributed across multiple storage repositories and multiple sites. The SRB provides access mechanisms that support standard Posix I/O functions. Based on previous work from others, I have implemented a driver that allows a DODS/DAP server to use the SRB, Storage Resource Broker (http://www.npaci.edu/DICE/SRB/), as a data storage system. (i.e. with this driver, DODS/DAP uses the files stored in SRB as if they were stored on local disk.)

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.

No. My approach to the implementation was to add SRB file handling methods in the server scripts. This involved reading and understanding the server scripts file fetching module. Although this specification covers most material an application programmer would need, it does not cover the material above, which had been a major part of my development.

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

Yes, it is accurate. In the specification, I have not noticed any inaccuracies or internal inconsistencies.

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

Yes, it is clear.

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?

Yes, it is balanced.

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?)

As a programmer, I found the tutorials on www.opendap.org to be more useful in terms of coding and learning DAP. But, I would use this specification as a guideline when developing DAP applications or make DAP server modifications.

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?)

I do not see any unreasonable implementation challenges DAP presents.