Week 7 Tutorial: MVC Architecture and Sessions

School of Information Technologies
COMP5347: Web Application Development
Week 7 Tutorial: MVC Architecture and Sessions
(Node.js/Express.js Application)
Learning Objectives
• Build an application with separate controller and router
• Understand and practice session
Part 1: Prepare folder structure
Task: Start Eclipse and open the project you have created in week 6. Create the folder
structure similar to Figure 1. Note that the “views” folder parallel to the “app” folder is
the one you created in week 6. You can leave it there as is.
Figure 1: MVC based folder structure
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Part 2: Install express-session Package
Express has got many modules that implement common functions for web
application development. One of these modules is express-session which provides
functions to manage sessions in Web applications. To use this module, you
suppose to download it (“express-session” module).
Managing Packages with Package.json
Before installing the express-session module, it is important to understand how to
manage dependencies in Node.js projects.
Package.json is a file that lists information about packages that your project
depends on. You should specify the name and version of any package you would
like to use in your project (e.g., express-session) to make your build reproducible
and hence easy to share with other developers. The name and version must
adhere to the semantic versioning rules1
.
A node.js project can be executed without “package.json” like what we did in the
previous tutorial session. The “package.json” play the role of recording installation
of each 3rd party module. If you share the project with the world, you do not have to
provide the entire node_module folder, but you need to specify these
packages/modules in the Package.json file. The “node_modules” folder can be
restored with the npm command “npm install” to install dependencies needed to
run your project2
.
To align with the best practice, you are suggested to use package.json with your
projects.
Task: To install express-session package, follow the one of the solutions below
(depending which machine you’re using):
- Solution 1 (Recommended): Download the “node_modules_W7.zip” from
Week 7 Module of COMP5347 Canvas site and extract the content from it.
Then remove the node_modules we used in week 6 tutorial from your Week 6’s
prject folder. Then copy the new node_module_W7 in Week 6’s project folder –
the new directory node_module_W7 contains the express-session module that
we have prepared for you. Then copy the “package.json” to the folder as well
(optional) – we have added the express-session package/module to this file.
- Solution 2: Run the command “npm install express-session” from your
project’s root directory in a commandline (CMD or PowerShell) to install the
session package.

1 https://docs.npmjs.com/getting-started/using-a-package.json
2 https://docs.npmjs.com/cli/install
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- Solution 3: If you already have a “package.json”, you can add the following line
at the end of the “dependencies”
"express-session": "^1.15.0"
Save the file and right click it on the project explorer panel to Run As then npm
update.
Part 3: Convert week 6 app to full MVC structure
Task: In the following steps, we use the sample code in Appendix A to convert week 6
application to full MVC structure. Make sure you put the files in correct location and
update their location reference accordingly in the code.
a) Create a JavaScript file survey.server.controller.js in folder app/controllers.
b) Create a JavaScript file survey.server.routes.js in folder app/routes.
c) Create a JavaScript file server.js in your project’s root directory. This is the entry file
that set up various configuration and start the server.
d) Copy the “survey.pug” you used last week to folder app/views; make sure you update
the form’s action to the correct URL. Copy “surveyresult.pug” from week 6 solution to
folder app/views
e) Now right click server.js on the project explorer panel and select from the dropdown
menu to ‘Run As” “Node.js application”
Part 4: Session Aware Survey
a) Appendix B show sample code of a simple session aware survey that will prevent
users from voting twice in 30 minutes interval using the same browser.
Task: Implement the code in your project and try to use chrome DevTools to inspect
the cookies in various request and response header.
b) Task: Now update the sample code to display more information in the result.
In particular, if a user has not voted before, the result page should look like Figure
2. Most of the change happens in the result template where you need to add
respective message depends on the session data. In the controller, you also need to
pass the user’s actual vote to the result template.
If a user has voted, the result page should look like Figure 3
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Figure 2: Result page for users who have not voted before
Figure 3: Result page for users who have voted
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Appendix A
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Appendix B