RDH handles bes:showCatalog request

From OPeNDAP Documentation

Point Of Contact: ndp

1 Description

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

The RDH receives and responds to a bes:showCatalog request for the Datasets (ODBC Data Sources) that it is offering.

2 Goal

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

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.

The BES receives a request for a catalog that it identifies as being serviceable by the RDH.

The RDH uses it's cached list of ODBC Data Sources to build a bes:showCatalog response and then returns the bes:response document to the client.

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.

client
A BES client application

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.

  1. The BES is installed and configured - including the correct installation and configuration of the RDH

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.

  • A client issues a bes:showCatalog command for the Datasets serviced by the RDH.

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)


  1. The BES receives a request containing a bes:showCatalog command for the RDH holdings. (How do we know it wants the RDH catalog? Will the RDH have it's own catalog? Or will it claim part of the resource URI space? Or something else? ndp)
    <?xml version="1.0" encoding="UTF-8"?>
    <bes:request xmlns:bes="http://xml.opendap.org/ns/bes/1.0#" reqID="[http-8080-1:16:bes_request]">
      <bes:setContext name="errors">xml</bes:setContext>
      <bes:showCatalog node="/data/stuff/" />
    </bes:request>
    Make sure to update this to match what we actuall use! ndp 16:27, 28 April 2009 (PDT)
  2. In the BES, the RDH is identified as the service will provide the requested catalog response.
  3. The RDH constructs a catalog response containing a Dataset entry for each ODBC Data Source in it's cached list of Data Source names.
  4. The RDH serializes the response document object back to the BES client:
    <?xml version="1.0" encoding="ISO-8859-1"?>
    <response xmlns="http://xml.opendap.org/ns/bes/1.0#" reqID="[http-8080-1:16:bes_request]">
      <showCatalog>
       <dataset catalog="catalog" count="18" lastModified="2008-07-16T23:59:34" name="/data/stuff" node="true" size="782">
        <dataset catalog="catalog" lastModified="2008-05-29T23:31:54" name="dataSourceOne" node="false" size="7944799">
          <serviceRef>dap</serviceRef>
        </dataset>
        <dataset catalog="catalog" lastModified="2008-05-29T23:31:54" name="dataSourceTwo" node="false" size="7944799">
          <serviceRef>dap</serviceRef>
        </dataset>
        <dataset catalog="catalog" lastModified="2008-05-29T23:31:54" name="dataSourceThree" node="false" size="7944799">
          <serviceRef>dap</serviceRef>
        </dataset>
       </dataset>
      </showCatalog>
    </response>
    Make sure to update this to match what we actuall use! ndp 16:27, 28 April 2009 (PDT)

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.

At the end of the Basic Flow the RDH will have returned to a ready state, awaiting the next transaction.

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
BES Data Provider The data server Assumed available as it is the framework from within which the RDH operates. Hardware running the BES.