Threads/Networking

Overview

For this homework you will implement an utility that allow us to find images present in a collection of web sites.

Objectives

This project is designed to help you practice:

Threads and synchronization
Networking
Text parsing

Grading

(55%) Tests (all public)
(25%) Correct use of threads to process urls
(20%) Using a shared collection to store results

Clarifications

Any clarifications or corrections associated with this project will be available at: Clarifications

Code Distribution

The project's code distribution is available by checking out the project named ImageFinder. The code distribution provides you with the following:

imageFinder package → Where you will provide your implementation
tests package

Specifications

For this homework you will implement a system that allow us to find urls of images present in a collection of web sites. In order to find these images we will use the static method Utilities.findImages (see code distribution) which takes a set of web sites and returns a set of urls that corresponds to images found (if any) in the specified sites.

To recognize images, your system will search through the html code of the specified web page, looking for entries starting with "<img src=" where any number of spaces and options (e.g., border) may exist in between img and src. An image is represented by the string following "src=". The following is a representative example of one possible entry you will be searching for:

The findImages method will return complete urls of images found. A complete url is defined as one that starts with "http://" and which provides the exact location of the image in such a way that we can cut and past the url in a browser and actually see the image. For this project you don't have to worry about sites that may use uppercase letters for img or src in the html code.

Requirements

You may not use regular expressions to identify images in a web page.
Your system must create a thread for each web site in such a way that the process of searching for images in all the web sites takes place concurrently. This is an important part of your implementation. You will lose credit if you limit the concurrency of your system or just have a sequential execution of threads.
Threads in charge of finding images must place the found images in a common collection (e.g., set). This is a shared resource and there can only be one collection that is used by all threads. Make sure you provide the appropriate synchronization.
Feel free to add any classes, methods, interfaces you understand are needed. Just make sure you place your implementation in the imageFinder package.
You do not need to provide any documentation for classes, methods, interfaces you provide.
You must attempt to submit your project immediately after checking out the project (even if you have not implemented any methods). This will allow you to verify that the submission process is working as expected.
You should submit your project often. This will keep versions of your project in the submit server that are easy to retrieve (you can also get previous versions from your CVS repository). If your computer crashes or you experience any other problem you will have a permanent backup in the submit server.
No student tests are required for this project but you are encourage to develop them as you implement this programming assignment.
Style
- Good variable names.
- You must avoid code duplication by calling appropriate methods (rather than cutting and pasting code). You may define your own private utility methods to perform often repeated tasks.
- Style as defined by the Eclipse Format Element option (Source → Format → Format Element) or as specified in Code Conventions for the JavaTM Programming Language (focus on the following sections: Indentation, Declarations, Statements, White Space, and Naming Conventions).
- Although you should avoid source lines exceeding 80 characters, you will not be penalize if they are present in your code.