COMP3322 Modern Technologies on World Wide Web
Assignment Four
Total 12 points
Deadline: 23:59 December 3, 2023
Overview
Write an express.js program and name it index.js. This program provides the API to get data about
big cities from a MongoDB server.
Objectives
1. A learning activity to support ILO 1 and ILO 2.
2. To practice how to use Node, Express, MongoDB, and Mongoose to create a simple REST API.
Specification
Assume you are using the MongoDB server running on the course’s node.js docker container with
the service name mongodb listening to the default port 27017.
The database is named "bigcities" and it contains a collection called "cities". The collection consists
of 34800 cities with a population of at least 10000. The data for this dataset is sourced from the
GeoNames geographical database (https://www.geonames.org/about.html). Each record in the
collection consists of 9 fields: _id, Name, “ASCII Name”, “ISO Alpha-2”, “ISO Name EN”, Population,
Timezone, “Modification date”, and Coordinates.
_id Name ASCII Name ISO Alpha-2 ISO Name EN
The id of record
in Geonames
database
The name of the
city (in UTF8)
The name of
the city (in
ASCII)
The ISO 3166
Alpha-2 country
code
The English
name of the
Alpha-2 code
Example 1 3862981 Cañada de Gómez Canada de
Gomez
AR Argentina
Example 2 1819729 Hong Kong Hong Kong HK Hong Kong,
China
Population Timezone Modification
date
Coordinates
The population
of the city
The IANA timezone
ID
The date of
last
modification
The latitude and
longitude values
of the city
Example 1 36000 America/Argentina/
Cordoba
2020-06-10 -32.81636,
-61.39493
Example 2 7482500 Asia/Hong Kong 2021-09-09 22.27832,
114.17469
Download the big cities dataset (bigcities.csv) from the course’s Moodle site. Import the data to the
bigcities database for the tests.
You will be using the provided framework for developing your program. You can download the
template file (template.txt) from the course’s Moodle site.
index.js
const express = require('express')
const app = express();
/* Implement the logic here */
// error handler
app.use(function(err, req, res, next) {
 res.status(err.status || 500);
 res.json({'error': err.message});
});
app.listen(3000, () => {
 console.log('Weather app listening on port 8000!')
});
TASK A
Use the command mongoimport to import the CSV file to the MongoDB server. Here are the steps to
import the data to your docker’s mongodb server.
1. Use Windows Explorer or Mac Finder to go to the data/db folder (which is inside the Nodedev folder).
2. Copy the bigcities.csv file there.
3. Access the docker desktop and open a terminal for the c33322-mongo container.
4. In the terminal, type this command (in one line):
mongoimport -d=bigcities -c=cities --type=csv --headerline --columnsHaveTypes --file=bigcities.csv
Write the code to set up a connection to the MongoDB server using Mongoose.
Use the following schema to access the database.
Schema {
 Name: String,
 'ASCII Name': String,
 'ISO Alpha-2': String,
 'ISO Name EN': String,
 Population: Number,
 Timezone: String,
 'Modification date': String,
 Coordinates: String
}
Write the code that monitors the database connection and terminates the program if the connection
to the database is lost.
TASK B
Write a routing endpoint to handle all GET requests to the URL
http://localhost:3000/cities/v1/all?gte=xxxxx&lte=yyyyy
for retrieving the entire big cities dataset or a portion of the dataset based on the population range
defined in the query string. The server should respond with a JSON message and an appropriate
HTTP status code that reflects the completion status of the GET request to the client.
Situations:
1. GET /cities/v1/all
When the GET request is made without a query string,
the program retrieves the entire dataset from the
database. It then converts the Coordinates field to an
object with two properties: ‘lat’ and ‘lng’. These
properties represent the latitude and longitude values
(both of type Number) of the city. The program returns
the entire dataset in JSON format to the client with the
HTTP status code 200. The returned JSON message is an
array that contains all the documents, ordered by the _id
field.
2. GET /cities/v1/all?gte=xxxxx
GET /cites/v1/all?lte=yyyyy
GET /cities/v1/all?gte=xxxxx&lte=yyyyy
When the GET request includes a query string with the ‘gte’ and/or ‘lte’ parameters, the
program retrieves the dataset from the database based on the population range specified by the
query string. ‘gte’ stands for  and ‘lte’ stands for . For example, the program retrieves all cities
with a population  one million for the parameter gte=1000000. Another example, the program
retrieves all cities with a population between 500000  x  1000000 for the parameters
gte=500000&lte=1000000. After retrieving the dataset, the program should convert the
Coordinates field to an object and sort the dataset in descending order of population. The
program then returns the dataset in JSON format to the client with HTTP status code 200.
The program should return a JSON string '{"error":"No record for this population
range"}' with the HTTP status code 404 when it could not find any documents matching the
limit defined by the parameters, e.g., lte=1000&gte=10000.
3. When the program experiences an error (e.g., database issue), it returns the HTTP status code
500 with a JSON string '{"error":$message}', where $message stands for the error message
of that error event.
TASK C
Create a routing endpoint that handles all GET requests to the URLs
http://localhost:3000/cities/v1/alpha
http://localhost:3000/cities/v1/alpha/{code}
for retrieving all the alpha codes in the dataset or all the documents in the dataset that match a
specified alpha code in the URL path. The server should respond with a JSON message and the
appropriate HTTP status code to indicate the completion status of the GET request.
Situations:
1. /cities/v1/alpha
With this GET request, the program searches the database to find
all unique alpha-2 codes in the dataset. For each alpha-2 code, the
program creates an object with two properties: 'code' and 'name',
which contain the values from the ISO Alpha-2 and ISO Name EN
fields, respectively. The program then groups all alpha-2 code
objects into an array and sorts them in ascending order based on
the alpha-2 codes. Finally, the program returns this array object as
a JSON message to the client with a status code of 200.
2. /cities/v1/alpha/{code}
With this GET request, the program searches the database to
retrieve all documents that match the specified alpha code in the
path. For example, if the requested path is '/cities/v1/alpha/HK', the
program will find all documents with the 'HK' alpha-2 code. For each
matched document, the program retrieves the following fields:
“ASCII Name”, Population, Timezone, and Coordinates. It converts
the Coordinates field to an object and groups all matched
documents in descending order based on population. The program
then returns this array object as a JSON message to the client with
status code 200.
The program should return a JSON string ‘{“error”:”No record for this alpha code”}’
with the HTTP status code 404 when it could not find any documents matching the requested
alpha code.
3. When the program experiences an error (e.g., database issue), it returns the HTTP status code
500 with a JSON string ‘{“error”:$message}’, where $message stands for the error message
of that error event.
TASK D
Create a routing endpoint that handles all GET requests to the URLs
http://localhost:3000/cities/v1/region
http://localhost:3000/cities/v1/region/{region}
for retrieving all the regions in the dataset or all the documents in the dataset that match a specified
region in the URL path. In response, the server returns a JSON message and appropriate HTTP status
code to the client, which reflects the completion status of the GET request.
Situations:
1. /cities/v1/region
With this request, the program retrieves the Timezone field of all
documents and extracts the first component of the Timezone field to be
the region. For example, if the Timezone value is
"America/Argentina/Cordoba", the program will extract the region as
"America". The program then returns all unique regions in the dataset as a
JSON message to the client with the HTTP status code 200. The JSON
message lists all regions in alphabetical order.
2. /cities/v1/region/{region}
With this GET request, the program searches the database
to retrieve all documents that have the first component of
the Timezone field matches the specified region in the
URL path. For example, if the requested path is
'/cities/v1/region/Atlantic', the program will find 72
documents. For each matched document, the program
retrieves only the following fields: “ASCII Name”, “ISO
Alpha-2”, “ISO Name EN”, Population, Timezone, and
Coordinates. It converts the Coordinates field to an object
and groups all matched documents in descending order
based on population. The program then returns this array
object as a JSON message to the client with status code
200.
The program should return a JSON string ‘{“error”:”No record for this region”}’ with
the HTTP status code 404 when it could not find any documents matching the requested region.
3. When the program experiences an error (e.g., database issue), it returns the HTTP status code
500 with a JSON string ‘{“error”:$message}’, where $message stands for the error message
of that error event.
TASK E
Create a routing endpoint that handles all GET requests to the URL
http://localhost:3000/cities/v1/{city}?partial=true&alpha=xx&region=yyyy&sort=alpha|pop
ulation
for retrieving all the documents in the dataset that match the specified city in the URL path. In
response, the server returns a JSON message and appropriate HTTP status code to the client, which
reflects the completion status of the GET request.
Situations:
1. /cities/v1/{city}
With this GET request, the program retrieves all documents in the database that have the “ASCII
Name” field exactly matches with the specified city name in the URL path. For example, when
the city name is “Logan”, the program returns only one document; whereas for the city name
“Paris”, it returns 4 matched documents. For each matched document, the program retrieves
the following fields only: _id, “ASCII Name”, “ISO Alpha-2”, “ISO Name EN”, Population,
Timezone, and Coordinates. It converts the Coordinates field to an object and groups all
matched documents in ascending order based on the _id field. The program then returns this
array object as a JSON message to the client with status code 200.
2. /cities/v1/{city}?partial=true
When a query string is provided with the parameter
“partial=true”, the program finds all documents where the
“ASCII Name” field partially matches with the specified city
name in the URL path. For example, when the city name is
“Logan”, the program returns 6 matched documents that
have the string “Logan” in their “ASCII Name” fields. If the
parameter “partial” has a value other than “true”, the
program should ignore this parameter and apply the exactly
match as the searching criteria.
3. /cities/v1/{city}?alpha=xx
/cities/v1/{city}?region=yyyy
When the query string contains the “alpha” parameter, the
program restricts the search to documents under this alpha
code for the exactly or partially matched of the city name
(based on the partial parameter). For example, if a search is performed on the city name "Logan"
with partial=true and alpha=AU, only one matched city is found.
When the query string contains the “region” parameter, the program restricts the search to
documents under this region for the exactly or partially matched of the city name. For example,
when searching for the city name “Logan” with partial=true and region=America, five matched
cities are located.
If both the alpha and region parameters are provided, the program should ignore the region
parameter as the alpha parameter should have a higher priority.
4. /cities/v1/{city}?sort=alpha|population
If the sort parameter is not included, the default order will be based on the ascending order of
the _id field. If the sort parameter is included with the value “alpha”, all returned results will be
sorted in ascending order of the alpha code. If the sort parameter is included with the value
“population”, all returned results will be sorted in the descending order of population.
Otherwise, ignore other values and use the default order.
5. The program should return a JSON string ‘{“error”:”No record for this city name”}’
with the HTTP status code 404 when it could not find any documents matching the requested
city name with the parameters.
6. When the program experiences an error (e.g., database issue), it returns the HTTP status code
500 with a JSON string ‘{“error”:$message}’, where $message stands for the error message
of that error event.
TASK F
Write a routing endpoint to intercept all other request types and paths, which are not defined in
previous tasks. Return a JSON string with the HTTP status code 400. For example, for the request
POST /cities/v1/all HTTP/1.1, we get the response '{"error":"Cannot POST
/cities/v1/all"}'; for the request GET /cities/alpha/AU HTTP/1.1, we get the response
'{"error":"Cannot GET /cities/alpha/AU"}'.
Resources
You are provided with the following files.
• template.txt – the framework for the index.js file.
• bigcities.csv – the big cities data set.
Testing platform
We shall run the server program in the node-dev container set and use Curl and Firefox to test the
API.
Submission
Please finish this assignment before 23:59 December 3, 2023 Sunday. Submit the following files:
1. A JSON file – use mongoexport to export the whole collection from the bigcities database.
Similar to the mongoimport command, you have to open a terminal at the data/db folder
and type the following command (in one line):
mongoexport -d=bigcities -c=cities --jsonArray --sort='{_id: 1}' --out=3035111999.json
Replace 3035111999 with your student ID and upload this JSON file.
2. The complete index.js program and other required files.
3. The package.json file of your express program.
Grading Policy
Points Criteria
2.0 Task A
▪ Database set up, import the data set, and export the data set.
▪ The program can connect and access the MongoDB database.
▪ The program can detect that the database connection is broken.
2.5 Task B
▪ Correctly handle the GET request to return all big cities data
▪ Correctly handle the GET request with query string parameters to return the
specific set of data
▪ Error handling
2.0 Task C
▪ Correctly handle the GET request to retrieve all the alpha-2 code in the big cities
dataset.
▪ Correctly handle the GET request to retrieve all cities that have the matched
alpha-2 code.
▪ Error handling
2.0 Task D
▪ Correctly handle the GET request to retrieve all unique regions in the big cities
dataset.
▪ Correctly handle the GET request to retrieve all cities that have the matched
region.
▪ Error handling
2.5 Task E
▪ Correctly handle the GET request to retrieve all cities that have the matched city
name or partially matched city name.
▪ Correctly handle the GET request to retrieve all cities that have the matched city
name or partially matched city name within a specific region/alpha-2 code and
sorting order.
▪ Error handling
1.0 Task F
▪ Error handling of all unknown methods and paths
-4.0 Using any external libraries.
Plagiarism
Plagiarism is a very serious academic offence. Students should understand what constitutes
plagiarism, the consequences of committing an offence of plagiarism, and how to avoid it. Please
note that we may request you to explain to us how your program is functioning as well as we may
also make use of software tools to detect software plagiarism.
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