Add the NcML handler to the BES

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Description

Give a short descriptive name for the use case to serve as a unique identifier. Consider goal-driven use case name.

Add the NcML handler to the BES

Goal

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

A person who is configuring a BES daemon adds the NcML handler and viola, the AIS and whatever else we do with NcML works now.

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.

The NcML handler creates a synthetic data set using some extra information, written using NcML, and an existing data set. The new information is added to, or replaces, the existing information in the data set.

NcML has the syntax to add to, supplant or remove attributes from a data set. It can also add new variables to a data set. In the design that goes with this use case we are proposing to implement only the attribute part of the NcML syntax initially and then add the capability to add variables later.

This use case covers just how the NcML handler is added to the BES and how it treats the .ncml files to make the synthetic data sets.

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.

A data provider or system administrator.

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.

  1. The BES is installed and configured, except for the NcML handler
  2. There are data sets and
  3. There is at least one NcML file under/within the BES' DocumentRoot

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.

The trigger is the (perceived or real) by the provider to add this feature to their data server. In the case of the REAP or IOOS projects, the AIS will be needed to build documents these projects need. Satisfying the requirements for those projects will be the triggers.

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)

  1. User (installer/configurer) installs (builds and installs or installs a binary) of the NcML handler code
  2. The user edits the BES.conf file so that any .ncml files are routed to the NcML handler
  3. The user (re)starts the BES

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.

Post Conditions

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

Activity Diagram

Here a diagram is given to show the flow of events that surrounds the use case. It might be that text is a more useful way of describing the use case. However often a picture speaks a 1000 words.

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.

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.

Other Resources

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