IEEE Geoscience and Remote Sensing Magazine - December 2015 - 15

as shown in Figure 5. This information can also be further
parsed and used to request data for a layer of interest.
Figure 6 illustrates how to acquire layer data from a particular product for a single spatial point for a range of dates.
The dictionary objects within the returned list contain: the
date and Julian date of acquisition; the latitude and longitude coordinates; the scaled data value; and the quality values for the particular pixel.
Assembling the arguments for a "get" request to the
middleware services can be complicated. The LP DAAC acknowledges that not all users have this skill set, or would
rather access data in a more simplified manner. For the users preferring not to use Python to consume the middleware services, the LP DAAC has developed a web application which allows the user to interact with and explore the
data before downloading for further analysis.
5. Web ApplicAtion for consuming
middleWAre services
Most users are not interested in becoming software engineers or data access experts. They might only desire quick
and easy access to data through a simple web client. They
could be interested in a limited amount of data, which does
not justify software development effort on their part. Alternately, they may just want a visual representation of data
for further investigation, and delay more demanding data
requests to a later time. More sophisticated users can develop their own client application interface to connect to
LP DAAC services, but for most user requests, a simple web
interface is an appropriate data access solution.
The LP DAAC middleware services are easily employable in web applications because they have been developed
using REST architecture best practices. For users preferring

figure 7. The AppEEARS Web Interface sample extraction form.
december 2015

ieee Geoscience and remote sensing magazine

interaction with a Graphical User Interface (GUI), the LP
DAAC has developed a web application named Application
for: Extracting and Exploring Analysis Ready Samples, or
AppEEARS. This web application is an intuitive and powerful data extraction tool that
leverages LP DAAC middleware services. AppEEARS
is designed to simplify user
built-in AppeeArs
requests and viewing of revisuAliZAtions AlloW
turned data, or alternately
users to vieW And
preview of results before
interAct WitH returned
deciding which data to ultidAtA from sAmple
mately return. To make a data
reQuests before
request, users simply enter
doWnloAd.
key parameters into a sample
extraction form. As shown in
Figure 7, users can request
MODIS land data from the LP
DAAC archive for an arbitrary number of geographic point
locations for a desired range of observation dates. AppEEARS in turn employs the underlying middleware services to
request the desired data from OPeNDAP and make them
available to the user.

figure 8. AppEEARS Interactive Data Visualization Interface.

Table of Contents for the Digital Edition of IEEE Geoscience and Remote Sensing Magazine - December 2015