Making an aggregation visible using the directory browsing features

From OPeNDAP Documentation

Back: BES Aggregation using NcML

Point Of Contact: James Gallagher

1 Description

Give a short descriptive name for the use case to serve as a unique identifier.


2 Goal

The goal briefly describes what the user intends to achieve with this use case.

When an aggregation has been described using NcML and the *.ncml file is being served it should show up in Hyrax's directory listings like a 'normal' data set. A downstream data processing element (DPE) or client should be able to work with it no differently than a normal data set. This includes both the DAP2-4 operations (get DAS, get DDX, et c.) but also the HTML directory listings and THREDDS catalogs.

3 Summary

Give a summary of the use case to capture the essence of the use case (no longer than a page). It provides a quick overview and includes the goal and principal actor.

When a DPE/client looks at a directory that contains *.ncml files, those files should be represented like any other data source by the BES. That means when a user looks at a directory of stuff served by Hyrax, the NcML files appears to be data set with the DAS, DDS, et c., links just like the HDF4, netCDF, ..., files.

This use case is really a reminder that this handler has to function like any other data hndler and with not be like the ASCII or HTML form handlers.

4 Actors

List actors, people or things outside the system that either acts on the system (primary actors) or is acted on by the system (secondary actors). Primary actors are ones that invoke the use case and benefit from the result. Identify sensors, models, portals and relevant data resources. Identify the primary actor and briefly describe role.

5 Preconditions

Here we state any assumptions about the state of the system that must be met for the trigger (below) to initiate the use case. Any assumptions about other systems can also be stated here, for example, weather conditions. List all preconditions.

6 Triggers

Here we describe in detail the event or events that brings about the execution of this use case. Triggers can be external, temporal, or internal. They can be single events or when a set of conditions are met, List all triggers and relationships.

7 Basic Flow

Often referred to as the primary scenario or course of events. In the basic flow we describe the flow that would be followed if the use case where to follow its main plot from start to end. Error states or alternate states that might be highlighted are not included here. This gives any browser of the document a quick view of how the system will work. Here the flow can be documented as a list, a conversation or as a story.(as much as required)

8 Alternate Flow

Here we give any alternate flows that might occur. May include flows that involve error conditions. Or flows that fall outside of the basic flow.

9 Post Conditions

Here we give any conditions that will be true of the state of the system after the use case has been completed.

10 Activity Diagram

Here a diagram is given to show the flow of events that surrounds the use case.

11 Notes

There is always some piece of information that is required that has no other place to go. This is the place for that information.

12 Resources

In order to support the capabilities described in this Use Case, a set of resources must be available and/or configured. These resources include data and services, and the systems that offer them. This section will call out examples of these resources.

Resource Owner Description Availability Source System
name Organization that owns/ manages resource Short description of the resource How often the resource is available Name of system which provides resource