HW#2 --- last modified October 18 2020 17:47:19.

Solution set.

Due date: Oct 5

Files to be submitted:
  Hw2.zip

Purpose: To gain experience with different kinds of NoSQL databases, in particular, key-value stores and graph databases.

Related Course Outcomes:

The main course outcomes covered by this assignment are:

CLO2 -- Be able to deploy and understand the use cases of a graph-based database.

CLO3 -- Be able to code an application that makes use of a database API to a NoSQL store.

Description:

This homework consists of two part, practicing FLWOR XQueries using with BaseX, writing a simple app to handle genealogy relationships using neo4j.

For the XQuery portion of the homework, I would like you to pick five websites of your choice that have RSS feeds. Download these feeds (include these files in your ZIP file) and load them into a BaseX database named RSSFeeds. Next I would like you to make FLWOR queries for the following (put these in a files flwor1.xq to flwor3.xq):

1. Return the titles of all news items (in any of your five feeds) from a particular day (you choose the day but have it set in a let expression).
2. Return all the news items containing the term Covid-19 in descending order of date, modifying the RSS format so that it matches Atom format.
3. Return the most recent date at which some term appears in a news item (specify the term in a let clause).

Include transcripts of you running your three queries on BaseX in the file xqueries.txt that you include in your ZIP file.

For the neo4j portion of the homework I'd like to create a genealogy project in neo4j which is controlled from a java program on the command line. This program should use memcached to cache query responses as indicated in what follows. You should have a readme.txt file that explains how you want me to set up your neo4j database. Any constants which need to be changed in your java program should clearly be indicated. I will compile your program from the command line using a line like:

javac genealogy.java

Do code your java program in a package, so that the above will work. I will then run your program with one of four lines:

java genealogy add_person name birth_year [death-year] 
java genealogy add_child child_name parent_name
java genealogy relationship name1 name2
java genealogy num_living_descendants name

You can assume I have correctly specified the CLASSPATH environment variable for both neo4j and memcache.

add_person should add a person entity with a given name (a name is a string that contains a full name such as Christopher John Pollett) with a given birth year and optional year of death to the neo4j database. Note: When supplying a command line argument that is a string which may contain spaces, you should double quote it. i.e.,

java genealogy add_person "Christopher John Pollett" 1970

The relationship and num_living_descendants operations should cache their outputs in memcached for 60 seconds. When these commands are run it should first check memcached for an answer.

Do some kind of reasonable error handling if arguments don't exist for any of the above operations.