Creating a Mashup

In this assignment, you will learn how to mashup the information published on the Web as RSS feeds. Mashups are situational applications: they are meant for specific, generally short lived, needs and thus have to be put together rather quickly and easily. RSS is a leading standard for publishing structured summaries of information (syndication) over the Web. Example uses of RSS include news headlines, blog posts, stock quotes, and weather information.

A popular way of creating mashups is to aggregate, manipulate, and republish the information published as RSS feeds by various providers. Visit Yahoo pipes to familiarize yourself with some simple and cool examples of mashups created by others. You will create your own mashup in this assignment using tools provided by Project Zero.

What is our Situation (Specific Need)?

John Q. Tourist of Raleigh wishes to plan a vacation trip during the period of 4/7 to 4/13. He does not have a strong preference about the location: he can go to either of New York City, Washington DC, or Miami. Being a bargain-lover, he wants to make sure he gets the best airline and hotel deal there is. However, John is discouraged by the daunting task of checking for deals on the Web every so often. How can we help him?

We find that Farecast publishes airline deals as RSS feeds. We also find that Expedia publishes a similar feed for hotel deals. At Farecast, we can create a custom RSS feed for deals to NYC (LGA), Washington DC (DCA), and Miami (MIA). At Expedia, we can create three custom RSS feeds, one for each city. Then, we can quickly develop an application using Project Zero to read these feeds, find the lowest cost city (air + 6 nights at a hotel), and publish a feed that shows information for air and hotel booking for the cheapest of the three cities. To remain focused on the best deals, our feed is updated only when a cheaper city and deal is found. Our application will simulate checking for updates at Farecast and Expedia every 7 seconds, by instead checking equivalent feeds found here:
http://bombadil.csc.ncsu.edu:8080/cscairdeals,
http://bombadil.csc.ncsu.edu:8080/cscmiamihotels,
http://bombadil.csc.ncsu.edu:8080/cscdchotels, and
http://bombadil.csc.ncsu.edu:8080/cscnychotels.
These feeds are updated every 7 seconds (to reduce testing time). So your scripts would read and publish updates every 7 seconds.

Part 1: Reading an RSS Feed

First you should learn how to read an RSS feed. This part is just a learning exercise and there are no deliverables associated with it. However, learning this part is essential for the final deliverables. We will use the Rome APIs (built-in support in Project Zero) for reading and creating RSS feeds.

First, create your custom RSS feeds at the simulated Farecast and the simulated Expedia for the cities John is interested in (one feed at Farecast, three separate feeds at Expedia). Save the URLs to each of these feeds.
Explore these Rome tutorials in general for the entire assignment. In particular, see this on how RSS feeds can be read.
Develop a zero application that reads one of your custom feeds and dumps the retrieved information. To do this
- Go through this documentation on how to add RSS support to a blank Zero project.
- Right click your ivy.xml -> zero tools -> resolve. This adds the requisite Rome libraries to your project.
- Following the above tutorial, write a simple Groovy script in your public folder to read a feed and output the retrieved feeds. You can run the script simply by pointing your browser to the URL for this script.
- Within your script, access the various fields of the feed entries, such as title, link, and description. For the airfare feeds, parse the title to extract the city and the fare amount.
At this point, you should feel comfortable with reading RSS feeds into your application.

Part 2: Publishing an RSS Feed

This part also is just a learning exercise, but essential for the final deliverables.

Go through this tutorial.
Write a public Groovy script that creates a feed from hypothetical data and outputs it as a file to your public folder.
Note that when you create your own feed, you have to specify the feedType. Use "rss_2.0" as the feed type in this assignment.
Try to read this feed (the URL will be the URL of your file) into the reader script developed in Part 1.
At this point, you should feel comfortable with publishing your own RSS feeds.

Deliverables

Upload to the dropbox a Project Zero project that includes the following components:

A Groovy script airdeals.groovy that reads Farecast feeds and publishes the results every 7 seconds to http://localhost:8080/myairdeals.
Groovy scripts nyc.groovy, dc.groovy, and miami.groovy that read Expedia feeds for the three cities and publish the results every 7 seconds to http://localhost:8080/mynychotels, http://localhost:8080/mydchotels, and http://localhost:8080/mymiamihotels.
An aggregator Groovy script cheapest.groovy that reads the above published feeds, picks the cheapest city in terms of air + 6 nights of hotel, and updates http://localhost:8080/mycheapestcity only when the newly available deal is better than the current cheapest deal. For Expedia feeds, assume that the published deals are available for John's travel dates.
A Groovy script showme.groovy that reads the aggregated feed every 7 seconds and shows the result. Here is a sample of what this result could look like.

Testing and Grading

Notice that the Farecast and Expedia deals do not change frequently enough for us to test whether your mashup updates correctly and finds the cheapest combination. For this reason, for testing purposes, we will replace your scripts that read from these providers with our scripts. Hence, your aggregator will be tested against our feeds. Our feeds will conform to the formatting of the Farecast and Expedia feeds. However, they will have hypothetical fares that update quite frequently. If your mashup eventually finds the cheapest combination from our feeds and does not update anymore, then it is correct.

We will run your project and fire browser requests to airdeals.groovy (ours), nyc.groovy (ours), dc.groovy (ours), miami.groovy (ours), and cheapest.groovy (yours). We will watch showme.groovy (yours) to see the result. We will check that the file public/mycheapestcity does not update once the best deal has been found.

Tips and Tricks for Solving the John Q. Tourist Situation

You will have to use the Java Timer API in your feed publisher scripts to fire them at regular intervals. Here is a useful tutorial. To avoid MissingMethodExceptions, you may want to put your TimerTask class in the Java folder of your project and simply schedule it from Groovy.
Your script that shows the final result needs to refresh every 7 seconds to show any updates. Find and use a simple HTML refresh mechanism.