OPeNDAP software

DChart
A Web interface for gridded and in-situ data collections
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What is DChart?

The Dapper Data Viewer (aka DChart) allows you to visualize and download in-situ oceanographic or atmospheric data from file or OpenDap server. Features include an interactive map that is draggable, an in-situ station layer that allows you to select data stations, and a plot window that allows you to plot data from one or more stations. Three plot types are supported (profile, property-property, and time series) and users can interact directly with the plot to pan or zoom in and out. Click here to try DChart.

What problem does DChart address?

Millions of in-situ ocean observations are now available to scientists through the OPeNDAP network protocol. However, access to this data is limited because there are few Web applications that support the in-situ OPeNDAP protocol.

What is the solution?

Several Web browser based technologies (XHTML/CSS/DOM/XML/XSLT and JavaScript) have matured over the last few years to the point where it is now possible to design OPeNDAP compatible Web applications with richer user interfaces than are possible with traditional Web technologies.

DChart is a Web application that takes advantage of this technology to allow interactive selection, browsing, plotting and downloading of in-situ observations from Dapper, an in-situ OPeNDAP server. Users have access to the functionality of a desktop application in a Web browser without having to download any plugins or applets.

Screen snapshot of DChart Web Page accessing Argo profile data.	Screen snapshot of DChart Web Page accessing National Data Buoy Center time series data.

Three plot types are supported (profile, property-property, and time series) and users can interact directly with the plot to pan or zoom in and out.

Technology

JavaScript remote scripting technology, also known as AJAX (Asynchronous Java and XML), provides a solution to this problem. There are two ideas behind an AJAX application:

• The application communicates with the Web server asynchronously:

(figure from Adaptive Path)

• JavaScript is used to regenerate portions of the user interface.

DChart uses remote scripting technology to provide web access to in-situ oceanographic or atmospheric data. Users have access to the functionality of a desktop application in a Web browser without having to download any plugins or applets.

Demonstration, references and more information: