Insight UBC: Deliverable 2

All code that follows should be considered as pseudo-code.

Do not copy and paste it on your project and hope that it works!

Disclaimer

Goals and specs

1. Add and remove a dataset containing information about UBC classrooms

Goals and specs

1. Add and remove a dataset containing information about UBC classrooms

rooms.zip

addDataset(...)

Parse it

Keep data structure in a variable

Save it to disk

Caching

same workflow as courses.zip BUT with different file types

 

InsightDatasetKind.Rooms

(kind)

Goals and specs

2. Answer queries about either UBC courses or rooms.

Goals and specs

Examples:

"what's the average of CPSC 340 ?"

2. Answer queries about either UBC courses or rooms.

Goals and specs

2. Answer queries about UBC courses. (current solution)

{
  "WHERE":{
    "AND": [
      { "IS":{ "courses_id": "*340*" } },
      { "IS":{ "courses_dept": "*cpsc*" }}
    ]
   },
   "OPTIONS":{
      "COLUMNS":[
         "courses_id", "courses_avg"
      ],
      "ORDER":"courses_avg"
   }
}

Goals and specs

{"result": [
  { "courses_id": "340", 
    "courses_avg": 68.4 },
  { "courses_id": "340", 
    "courses_avg": 68.4 },
  { "courses_id": "340", 
    "courses_avg": 72.65 },
  { "courses_id": "340", 
    "courses_avg": 72.65 },
  { "courses_id": "340", 
    "courses_avg": 72.94 },
  { "courses_id": "340", 
    "courses_avg": 72.94 },
  ...
]}
{
  "WHERE":{
    "AND": [
      { "IS":{ "courses_id": "*340*" } },
      { "IS":{ "courses_dept": "*cpsc*" }}
    ]
   },
   "OPTIONS":{
      "COLUMNS":[
         "courses_id", "courses_avg"
      ],
      "ORDER":"courses_avg"
   }
}

not what we
were looking for

2. Answer queries about UBC courses. (current solution)

Goals and specs

2. Answer queries about UBC courses. (new query engine)

{
  "result": [
    {
      "courses_id": "340",
      "overallAvg": 75.69
    }
  ]
}
{
  "WHERE":{
    "AND": [
      { "IS":{ "courses_id": "*340*" } },
      { "IS":{ "courses_dept": "*cpsc*" }}
    ]
   },
   "OPTIONS":{
      "COLUMNS":[
         "courses_id", "overallAvg"
      ]
   },
   "TRANSFORMATIONS":{
      "GROUP":[ "courses_id"],
      "APPLY": [
      	{
      	  "overallAvg": {
      	    "AVG": "courses_avg"
      	  }
      	}
      ]
   }
}

this is the right result!

Goals and specs

2. Answer queries about UBC courses. New EBNF:

QUERY ::='{'BODY ', ' OPTIONS (', ' TRANSFORMATIONS)? '}'

BODY ::= 'WHERE:{'  (FILTER)? '}'
OPTIONS ::= 'OPTIONS:{' COLUMNS ', ' (SORT)?'}'
TRANSFORMATIONS ::= 'TRANSFORMATIONS: {' GROUP ', ' APPLY '}'

FILTER ::= (LOGICCOMPARISON | MCOMPARISON | SCOMPARISON | NEGATION)

LOGICCOMPARISON ::= LOGIC ':[{' FILTER ('}, {' FILTER )* '}]'  
MCOMPARISON ::= MCOMPARATOR ':{' key ':' number '}'  
SCOMPARISON ::= 'IS:{' key ':' [*]? inputstring [*]? '}'  // inputstring may have option * characters as wildcards
NEGATION ::= 'NOT :{' FILTER '}'

LOGIC ::= 'AND' | 'OR' 
MCOMPARATOR ::= 'LT' | 'GT' | 'EQ' 

COLUMNS ::= 'COLUMNS:[' (key ',')* key ']' 
SORT ::= 'ORDER: ' ('{ dir:'  DIRECTION ', keys: [ ' key (',' key)* ']}' | key) 
DIRECTION ::= 'UP' | 'DOWN'  

GROUP ::= 'GROUP: [' (key ',')* key ']'                                                          
APPLY ::= 'APPLY: [' (APPLYKEY (', ' APPLYKEY )* )? ']'  
APPLYKEY ::= '{' key ': {' APPLYTOKEN ':' key '}}'
APPLYTOKEN ::= 'MAX' | 'MIN' | 'AVG' | 'COUNT' | 'SUM'                           

key ::= string '_' string
inputstring ::= [^*]* // zero or more of any character except asterisk.

Activity #1

Take a few minutes and discuss with your partner what strategies could be used to integrate the new data set into your existing solution. 

 

Share your strategy (not your code) with other teams.

  - Are they equal? 

  - How they differ?

  - Which one better suits our problem? 

  - Wait. Do we have a problem? What is our problem?

10~15 min

addDataset(...)

new code

kind?

existing code

parse courses

parse rooms

Keep data structure in a variable

Save it to disk

Activity #1. Do we have a problem?


return new Promise(function (fulfill, reject) {
    try {
        const myZip = new Zip();
        if (kind === InsightDatasetKind.Courses) {
            // Extract the content
            zip = myZip.extract();
            for (file in files inside zip) {
                try{
                    contents = file.getContent();
                    for (section in results) {
                        // do something
                    }
                } catch (err) {
                    // do something
                }
            });
            // more code here
        } else if (kind === InsightDatasetKind.Rooms) {
            // We are just going to copy and paste the code above and generate ourselves a problem
        } else {
            // keep doing the same strategy until our code is doomed
        }
        // more code here
        // even more code
        // ...
    } catch (err) {
        // do something
    }
});

Do we have a problem?


return new Promise(function (fulfill, reject) {
    try {
        const myZip = new Zip();
        if (kind === InsightDatasetKind.Courses) {
            // Extract the content
            zip = myZip.extract();
            for (file in files inside zip) {
                try{
                    contents = file.getContent();
                    for (section in results) {
                        // do something
                    }
                } catch (err) {
                    // do something
                }
            });
            // more code here
        } else if (kind === InsightDatasetKind.Rooms) {
            // Extract the content
            zip = myZip.extract();
            for (file in files inside zip) {
                try{
                    contents = file.getContent();
                    for (rooms in results) {
                        // do something
                    }
                } catch (err) {
                    // do something
                }
            });
            // more code here
        } else {
            // keep doing the same strategy until our code is doomed
        }
        // more code here
        // even more code
        // ...
    } catch (err) {
        // do something
    }
});

1. software readability

2. software maintainability

3. software testability

 

Do we have a problem?

A few words about code complexity

<sneak peak of the next tutorial>

Jack the Ripper will claim his 5th victim in the DatasetController district....


return new Promise(function (fulfill, reject) {
    try {
        const myZip = new JSZip();
        if (kind === InsightDatasetKind.Courses) {
            // Extract the content
            zip = myZip.extract();
            for (file in files inside zip) {
                try{
                    contents = file.getContent();
                    for (section in results) {
                        // do something
                    }
                } catch (err) {
                    // do something
                }
            });
        } else if (kind === InsightDatasetKind.Rooms) {
            // We are just going to copy and paste the code above and generate ourselves a problem
        } else {
            // keep doing the same strategy until our code is doomed
        }
        // more code here
        // even more code
        // ...
    } catch (err) {
        // do something
    }
});
return new Promise(function (fulfill, reject) {
    try {
        const myZip = new JSZip();
        if (kind === InsightDatasetKind.Courses) {
            // Extract the content
            zip = myZip.extract();
            for (file in files inside zip) {
                contents = this.parseCoursesFile(file);
            });
        } else if (kind === InsightDatasetKind.Rooms) {
            // We are just going to copy and paste the code above and generate ourselves a problem
        } else {
            // keep doing the same strategy until our code is doomed
        }
        // more code here
        // even more code
        // ...
    } catch (err) {
        // do something
    }
});

calls the method that encapsulates the behavior of parsing a single file

private parseCoursesFile(file): <figure out this type> {
     const result = <something>;
     try{
        contents = file.getContent();
        for (section in results) {
            // do something
        }
    } catch (err) {
        // do something
    }
    return result;
}

Refactoring

Is the process of restructuring existing code without changing its behavior -- Wikipedia

Extract method: roughly moves some code to a smaller and well contained method

Activity #2

Now that we have a glimpse about how to encapsulate some of the dataset behavior into methods. Discuss with your partner about at least 3 methods that you can extract for the addDataset method.

 

  - Does this help you integrating the new rooms dataset?

  - How can you be sure that your code still works after refactoring?

~5 min

Activity #2

  - Does this help you integrating the new rooms dataset?

Your code should be open for extension, but close for modification [more to come]

Test suites! Never change your code if you don't have tests that cover that functionality

  - Methods e.g.

- parseCourses ( zip )

- parseCoursesFile ( file )

- parseRooms ( zip )

- parseRoomsFile ( file )

- saveToDisk ( your datasets data structure )

  - How can you be sure that your code still works after refactoring?

Activity #2

D2 - Further clarifications

The rooms dataset

index.htm
/campus/
/campus/discover/
/campus/discover/buildings-and-classrooms/
/campus/discover/buildings-and-classrooms/AAC
/campus/discover/buildings-and-classrooms/ACEN
/campus/discover/buildings-and-classrooms/ACU
/campus/discover/buildings-and-classrooms/AERL
/campus/discover/buildings-and-classrooms/ALRD
...

- Files in HTML format, parsable using the parse5 package

- Each file other than index.htm represents a building and its rooms

- All buildings linked from the index should be considered valid buildings

zip.files

?

?

single file
e.g. AAC

your datastructure

parse5 datastructure

parse5

const document = parse5.parse(<my file>) as parse5.AST.Default.Document;*

* code snippet taken from http://inikulin.github.io/parse5/
* sample html/output taken from http://astexplorer.net/#/1CHlCXc4n4 

<html>
<body>
<h1>
<p>
My first heading
My first paragraph

- Inspect the html files in the dataset, take a look at them and try to find useful information

tree node for that element

current html element that I'm inspecting

Demo

HTTP

GET http://skaha.cs.ubc.ca:11316/api/v1/team666/6245%20Agronomy%20Road%20V6T%201Z4
6245 Agronomy Road V6T 1Z4
6245%20Agronomy%20Road%20V6T%201Z4

address

URL-encoded address

status: 200,
body: {"lat":49.26125,"lon":-123.24807}

request

response

* Take a look at https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol for a more comprehensive explanation of HTTP

client

server

const request = require('request');

request({ 
     method: 'GET', 
     uri: 'http://skaha.cs.ubc.ca:11316/api/v1/team6/6245%20Agronomy%20Road%20V6T%201Z4',
     gzip: true
}).on('response', function(response) {
     console.log("status: " + response.statusCode);
}).on('data', function(data) {
     // decompressed data as it is received
     console.log('decoded chunk: ' + data)
});
status: 200
decoded chunk: {
    "lat":49.26125,
    "lon":-123.24807
}

* https://github.com/request/request

* This code will not work in your project ! You are supposed to use the http package instead of request.

HTTP

const request = require('request');

request({ 
     method: 'GET', 
     uri: 'http://skaha.cs.ubc.ca:11316/api/v1/???',
     gzip: true
}).on('data', function(data) {
     // decompressed data as it is received
     console.log('decoded chunk: ' + data)
}).on('response', function(response) {
     console.log("status: " + response.statusCode);
});
status: 404
decoded chunk: {
    "code":"ResourceNotFound",
    "message":"/api/v1/ does not exist"
}

HTTP

* https://github.com/request/request

* This code will not work in your project ! You are supposed to use the http package instead of request.

Query Aggregation

[
    { "courses_uuid": "1", "courses_instructor": "Jean",  "courses_avg": 90, "courses_title" : "310"},
    { "courses_uuid": "2", "courses_instructor": "Jean",  "courses_avg": 80, "courses_title" : "310"},
    { "courses_uuid": "3", "courses_instructor": "Casey", "courses_avg": 95, "courses_title" : "310"},
    { "courses_uuid": "4", "courses_instructor": "Casey", "courses_avg": 85, "courses_title" : "310"},
    { "courses_uuid": "5", "courses_instructor": "Kelly", "courses_avg": 74, "courses_title" : "210"},
    { "courses_uuid": "6", "courses_instructor": "Kelly", "courses_avg": 78, "courses_title" : "210"},
    { "courses_uuid": "7", "courses_instructor": "Kelly", "courses_avg": 72, "courses_title" : "210"},
    { "courses_uuid": "8", "courses_instructor": "Eli",   "courses_avg": 85, "courses_title" : "210"},
]

Query Aggregation

{
	"WHERE": {
        "GT": { "courses_avg": 70 }
	},
	"OPTIONS": {
		"COLUMNS": ["courses_title", "overallAvg"]
	},
	"TRANSFORMATIONS": {
		"GROUP": ["courses_title"],
		"APPLY": [{
			"overallAvg": {
				"AVG": "courses_avg"
			}
		}]
	}
}

Query Aggregation

[
    { "courses_uuid": "1", "courses_instructor": "Jean",  "courses_avg": 90, "courses_title" : "310"},
    { "courses_uuid": "2", "courses_instructor": "Jean",  "courses_avg": 80, "courses_title" : "310"},
    { "courses_uuid": "3", "courses_instructor": "Casey", "courses_avg": 95, "courses_title" : "310"},
    { "courses_uuid": "4", "courses_instructor": "Casey", "courses_avg": 85, "courses_title" : "310"},
    { "courses_uuid": "5", "courses_instructor": "Kelly", "courses_avg": 74, "courses_title" : "210"},
    { "courses_uuid": "6", "courses_instructor": "Kelly", "courses_avg": 78, "courses_title" : "210"},
    { "courses_uuid": "7", "courses_instructor": "Kelly", "courses_avg": 72, "courses_title" : "210"},
    { "courses_uuid": "8", "courses_instructor": "Eli",   "courses_avg": 85, "courses_title" : "210"},
]

210 group
310 group
[
    { "courses_uuid": "1", "courses_instructor": "Jean",  
      "courses_avg": 90, "courses_title" : "310"},
    { "courses_uuid": "2", "courses_instructor": "Jean",  
      "courses_avg": 80, "courses_title" : "310"},
    { "courses_uuid": "3", "courses_instructor": "Casey", 
      "courses_avg": 95, "courses_title" : "310"},
    { "courses_uuid": "4", "courses_instructor": "Casey", 
      "courses_avg": 85, "courses_title" : "310"},
]
[
    { "courses_uuid": "5", "courses_instructor": "Kelly",   
      "courses_avg": 74, "courses_title" : "210"},
    { "courses_uuid": "6", "courses_instructor": "Kelly",   
      "courses_avg": 78, "courses_title" : "210"},
    { "courses_uuid": "7", "courses_instructor": "Kelly",   
      "courses_avg": 72, "courses_title" : "210"},
    { "courses_uuid": "8", "courses_instructor": "Eli",     
      "courses_avg": 85, "courses_title" : "210"},
]
avg: 77.25
avg: 87.5
let aux = [
 {x:1, y:1}, {x:2, y:2},  {x:1, y:1},
 {x:4, y:2}, {x:3, y:3},  {x:6, y:3},
 {x:4, y:3}, {x:-1, y:3}, {x:5, y:2},
 {x:1, y:2}, {x:2, y:2},  {x:3, y:1},
 {x:4, y:2}, {x:-2, y:3}, {x:2, y:4},
 {x:4, y:1}, {x:2, y:3},  {x:1, y:5},
 {x:9, y:3},
]

Activity #3

- Suppose you are given the grouped set below where each element has 2 coordinates, x and y.

- Someone decided to apply the LINEAR function to that group

- Write a method that computes the LINEAR

LINEAR = \frac{\sum( f(x))}{\sum( f(y))}
f(x) = x^2
f(y) = | y - 6 |

10~15 min

var linear = (acc, cur) => acc + Math.pow(cur.x, 2) / Math.abs(cur.y - 6)
aux.reduce(linear, 0)

Activity #3

- for loop

var acc = 0;
for (cur of aux) {
    acc += Math.pow(cur.x, 2) / Math.abs(cur.y - 6)
}

- reduce

both achieve the same result

- Linear is not protected against divisions by 0 [{ x: ?, y = 6}].

  What happens in that case?

[{x:2, y:6}, {x:3, y:4}].reduce(linear, 0)
Infinity

General tips and advice

#D1

#D1

D2 postponed tasks

Me trying to assist you in the day of the deadline

team that finished before grace period

Start early. Fail early.
Have enough time to fix things.

#1

Midterms season may start soon.

Make a schedule.

Divide your time.

#2

Whenever you have a problem, try to:

1. Describe what you're trying to do

2. Describe what is happening

3. Write a test case that encapsulate 1 and 2

4. Work using that single test as means to isolate your problem

#3

D2 - Extra slides

Debuging demo

.on('data', function(data) {
     // decompressed data as it is received
     console.log('decoded chunk: ' + data)
})

HTTP

* Network courses cover this in more detail

complete response body does not fit the bandwidth

Hence, we break it small chunks that can be sent through the pipeline.

The client has to rebuild the response on its own.

Thankfully, our response is small enough to fit in a single package

...

FYI: What happens if my response has 100mb and my pipe can only carry packages 10mb long?

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