Use Case 16: Preview Granule (metadata driven)

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Use Case EIE16: Preview Granule (Metadata driven)

for

ESIP Earth Information Exchange


Version 1.0 draft

Prepared by Karl Benedict

Earth Data Analysis Center, University of New Mexico

November 22, 2005


Contents

1.Use Case Identification

1.1.Use Case Number

EIE16

1.2.Use Case Name

Provide a standard preview of a data granule as referenced by an element in the granule metadata.

2.Use Case Definition

This use case represents a need to provide system users a preview of a data granule that they are considering for use or download. This preview would be encoded into the metadata for the granule, and be accessible via a simple URL. The preview may be generated by a service or represented by a static image file (browser supported) accessible via the URL, but access should be via a simple URL request.

2.1.Actors

User

2.2.Preconditions

  • 1.User has been presented with a list of granules (Use case EIE09)
  • 2.If the metadata for a listed granule provides a preview URL, a link to that URL will be included in the granule listing.

2.3.Postconditions

  • 1.The user is provided with a preview image

2.4.Normal Flow

  • EIE16.0.1) When a list of granules is generated as a result of a granule listing, available preview URLs are read from the metadata records
  • EIE16.0.2) Preview links are added to the listing of granules, as available.

2.5.Alternative Flows

Metadata do not contain preview URLs:

  • EIE16.1.1) Granules lacking preview URLs are listed without corresponding links.

2.6.Exceptions

Preview file returned by URL is not a valid image file. Display an error message to the user and log the error.

2.7.Extension Points

None

2.8.Priority

High

2.9.Frequency of Use

Invoked multiple times per session

2.10.Business Rules

None

2.11.Special Requirements

URLs corresponding with preview images must return a valid image file.

2.12.Assumptions

None

2.13.Notes and Issues

Recommendations regarding performance requirements and file sizes should be produced to provide a reasonable system response when providing preview images. Computationally intensive 'live' previews might be discouraged.

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