1 The DODS Client and Server Toolkit

The Distributed Oceanographic Data System (DODS) is a system used to facilitate access to scientific data on the internet. Using DODS, you can turn any data analysis program that uses one of several data access APIs into a powerful, internet-friendly data browser. For basic information about the structure of DODS and its components, please see The OPeNDAP User Guide.

The DODS Toolkit software consists of a collection of C++ classes used to build DODS data servers and clients:  

Type classes

A complete implementation of the DODS data access protocol (DAP). This consists of a set of virtual classes for different types of data, which must be sub-classed to use.

Data classes

This is a set of classes, including both the Data Descriptor Structure (DDS) and the Data Attribute Structure (DAS), designed to contain information about a dataset's data.

Connect classes

These classes are used by a DODS client to mimic a durable connection to a DODS server.

DODSFilter

This class consists of several utility functions useful for writing DODS servers.

CGI Utilities

The file cgi_util.h describes a small number of other common functions needed by DODS servers.

The DAP toolkit contains three class hierarchies: one for each of the DAS and DDS objects, rooted in classes with those names, and one for the variables, rooted at the class BaseType. The following sections present an overview of these class hierarchies and describe, in general terms, how they are used to build the client-library and data server. See Section 1.1 for information about the DDS and DAS classes. To use the type classes, they must be subclassed. Chapter 3 provides a detailed description of this process.

Detailed information about the DAS and DDS themselves is available in the The OPeNDAP User Guide. Descriptions of the classes and their member functions are in the reference material , The DODS Toolkit Reference.

The DODS toolkit also contains two classes used by DODS clients to manage network connections between themselves and a server. The Connect object manages a single connection with some DODS server, and the Connections object manages a group of Connect objects. The Connect class is meant to be subclassed when used by a real client library. See Chapter 2.

• 1.1 The DAS and DDS Objects
  • 1.1.1 The DAS Object
  • 1.1.2 The DDS Object
• 1.2 The Type Hierarchy
  • 1.2.1 Common Ancestor: BaseType
  • 1.2.2 Simple Types
  • 1.2.3 Vector Types: Array, List
  • 1.2.4 Compound Types: Structure, Sequence, Function, Grid