WebFund 2016W Lecture 19

Video

The video from the lecture given on March 22, 2016 is now available.

There is no need to use the course VM to set up of connect to an instance
- This is intended as a substitute for the VM
There are various options to get your web application on the instance:
- WINSCP
- wget [URL]
- Others...
You can create multiple sessions to the same instance with SSH

Extended until Sunday (March 27) at 11:55 pm
Extra functionality (2% bonus) will be at the TA’s discretion
If things are running slowly for you, try testing with files no larger than 1000 entries
If database has too many entries, drop them
- To drop: db.logs.drop()
  - This is done from the Mongo terminal client
“Show” shows the entries in a scrollable textbox

By default, documents in MongoDB can be up to 16 megabytes
For what we are doing, nothing should ever exceed this size since we are breaking files up into multiple documents
GridFS can be used to store larger documents
- It will split these larger documents into chunks sized 255 kB each

This will involve making assignment 5 into a single-page web appliction
Look at exam-storage to see an example of how to make a single-page application using client-side code

The base application analyzes text entered by the user and counts word frequencies to display in a graph
Division between client and server:
- Server: dumb web server (one route to render index)
- Client: everything (all the functionality, ie. interact.js)
In index.jade, we can see that some client-side scripts are linked and many of the HTML elements have IDs
- These IDs are used in the client-side script to easily access the elements using jQuery
It is important to understand the control flow when clicking on the update button
- The click event for the button causes a function to be called
- In this function, the user-entered data is taken from the page using jQuery
- Based on the settings specified by this data, words frequencies are counted and the graph is created
What does the map method do?
- It processes each element of an array, passing that element in to a function
- The return value of the function is put into a new array

If VM runs out of space, things may break
- Be careful, clean up space
- See the forums for a way to minimize the space MongoDB takes up

In this lecture we discussed interactive-graphs, the code for Tutorial 9.