Additional Information on RDV Usage

RDV Demonstration of DataTurbine Feeds from Taiwan's Kenting Coral Reef (KCR) and San Diego's Santa Margarita Ecological Reserve (SMER)

Overview
    The Real-time Data Viewer (RDV) user interface has been significantly simplified for the purpose of providing a user-friendly desktop presentation of DataTurbine's capabilities for real-time data and video streaming. The main theme of this demonstration is the ability to distribute heterogeneous synchronized data streams from geographically disparate sources over the Internet. This theme is implemented here by aggregating real-time data and video streams from two distant sites. The first is from a DataTurbine deployment at Kenting Coral Reef in Taiwan, where a video observatory was deployed in 2004. The second is the Santa Margarita Ecological Reserve at which a camera and sensor array, served by a National Instruments CompactRIO, were deployed in 2007. Data from both of these sites is being streamed through local DataTurbine servers and aggregated by a DataTurbine server at UC San Diego (UCSD).

RDV Configuration
    The ability to specify configurations of which data streams to view and how to view them is central to implementing a demonstration such as this. This accomplished using a technology called the Java Network Launch Protocol (JNLP), also called "Java Webstart". This allows the invocation of a Java program that is downloaded and run on demand on a client computer's Java Virtual Machine (JVM) via http. JNLP also allows specification of command-line arguments to the program being launched, one of which is the URL of a highly customized configuration file that specifies the views that are presented in this demonstration to a high level of detail.

Demonstration Architecture
    These data streams are accumulated from their respective geographical locations using the three routing mechanisms that are available in DataTurbine to compose real-time data streaming topologies. KCR data is mirrored to UCSD, and SMER data is shortcut routed from an intermediate DataTurbine server that serves as the parent node in a parent-child route from the SMER site. niagara.sdsc.edu hosts an http server that presents the JNLP specification file that instructs the download and execution of RDV from niagara to use yet another specification file that is presented over http by niagara to instruct the DataTurbine server to which to connect and which channels to subscribe to, as well as to completely customize the RDV view.

RDV in a Nutshell
preconfiguration of real-time data views from both SMER and KCR have been prepared to be invoked easily via JNLP. Simply clicking the following links will start preconfigured RDV instances:
Kenting Coral Reef
Santa Margarita Ecological Reserve

• Once started via one of the JNLP links above, some of RDV's features can be explored. This will be presented in the order of accessing RDV's functionality and operating the player from past time points (1-3),  and (4) managing DataTurbine datapanel configurations.
  • View Menu - controls which of RDV's functional components are visible in the display. The default is to have a clear display area.
    
  1. Show channels - toggles a list of the source names and channels that are available on the connected DataTurbine server.
  2. Show control panel - toggles a panel of controls for the time index that defines RDV's state and operate the player functionality.
  3. Notes about using the control panel, starting at the top of the stack of three rows;
     • VCR-like controls to either view the current data stream(s) in real time or to play-back from some point in time in the past, which is indicated by the green ball on the time line described in the following bullet.
       Playback rate is an integer multiplier for the speed at which playback occurs from the green ball.
       Time scale indicates how much of a time interval is being represented in currently active data panels. Note that timescale has no meaning for some types of data panels, such as the video/photo data panel.
     • A time line that is scaled to the interval described below; the green ball indicates the DataTurbine time index currently being examined by RDV.
       This can be directly manipulated by the user's pointing device.
     • Indication of the time interval represented by the DataTurbine ring buffer for the currently selected channels being examined in the format:
       start - length - end
  4. Window Menu -  allows creation of different kinds of datapanels from a list - these are most easily populated by dragging channels name from the channel list.

• Video/Photo Data Panel - displays jpeg images and mjpeg video.
  
• Time Series Data Panel - displays a time series as a chart. This form of display is fundamental to DataTurbine, which essentially maintains timestamp-indexed data streams.
  
• XY Data Panel - plots the ranges of two time series against each other in a 2D plot.
  
• RDV offers two conveniences for data panel usage:
1. Tear off data panel - removes the data panel from the RDV interface and puts it into its own resizable window. The datapanel's "torn off" state can be toggled by clicking on the small arrow symbol in the upper right corner of the datapanel.
2. Edit data panel label - right-clicking the title bar of a data panel will present a menu by which the ability to apply text to data panels can be chosen. It is usually desirable to uncheck "show channels in title" when performing this customization.