Explicit API
Use Cases
Description
Write an client for oc that is a command line tool which allows constraints and prints the desired schema and the data (when appropriate) in the getdap format.
Goal
This use case is designed to identify the essential functions that are required in order for a command line client from the current Ocapi code to be replicated in the oc.
Summary
The current Ocapi code has undergone a major rewrite which has provided a new branch of the original code called oc. The oc code branch is approximately half the size of the Ocapi code branch and the complexity of the code is reduced dramatically. The Ocapi code has a client that is a command line tool to allow an end user to access a desired schema, with or without constraints, and have that schema printed out in a special format. This use case is designed in principal, to see if the new oc code will allow for the same functionality as the Ocapi code in order to achieve the same results that the Ocapi currently provides. If the oc code is not as capable as the current Ocapi code this use case will identify the missing criteria and give a general idea of how much coding it will take to get the new oc code branch on the same functionality level as the Ocapi code branch. If the oc proves to be a more efficient means of running the c library then it is plausible that the oc code will be adopted as the current Ocapi code and any new development will occur on this code branch and the Ocapi code will no longer be maintained.
Note: Since it appears that the oc code does not include functions to print the results of a query, we might take this as an opportunity to write functions that mimic libdap's output functions/methods and not those of the current Ocapi library.
Actors
Primary: end user- this is any individual that is using the system to retrieve data utilizing the dap standard for individual use C libraries Api's Clients
Preconditions
The oc code must be properly compiled with no errors. The oc code must contain all necessary functions in order to achieve the desired outcome. These include functions that allow the data to be read in and printed in the appropriate format, allow constraints, proxy support, http authentication, SSL, cookies, compression, .dodsrc file support, and password and username provisions.
Triggers
An end user downloads the oc code, builds and compiles the code. A command line is open and the newly created get_oc client is initiated with a proper url and constraints if desired.
Basic Flow
1.Identify constraints 2.Initialize the oc 3.Provide proxy support 4.Provide http authentication 5.Provide SSL support 6.Allow for the das, dds, and dods schemas 7.Read url specified 8.Retrieve the data from the above url 9.Print the data
Alternate Flow
Provide error handling for all of the specific functions listed above
Post Conditions
The oc code will compile error free. The end user will request data using the new client (that has been copied from, or based on, the current Ocapi and/or libdap code) and that particular data set requested will be returned and printed to the screen.
Activity Diagram
Notes
The oc code has to be able to read and print sequences, arrays, structures, strings, primitive data types, array of structures, nested sequences, grids, and nested structures.
Resources
Resource: oc code and Ocapi code Owner: OPeNDAP Description: c library for dap protocal Availability: continuous availability Source System: OPeNDAP web site
