CS计算机代考程序代写 SQL javascript js flex Java database COMP5347 Web Application Development Node.js: MVC Architecture Introduction to MongoDB

COMP5347 Web Application Development Node.js: MVC Architecture Introduction to MongoDB
Dr. Basem Suleiman
School of Computer Science
The University of Sydney
Page 1

Outline
– Implementing MVC basics – Application Folder Structure
– CommonsJS modules – Controller and Routers
– Session Management
– Database Layer
– Introduction to NoSQL
– Introduction to MongoDB
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Page 3

The Survey app (Week 5 lab)
var express = require(‘express’)
var path = require(‘path’)
var bodyParser = require(‘body-parser’);
var app = express()
var products=[‘iphone 7’, ‘huawei p9’, ‘Pixel XL’, ‘Samsung S7’] var surveyresults = { fp:[0,0,0,0],mp:[0,0,0,0]} app.use(express.static(path.join(__dirname, ‘public’))); app.use(bodyParser.json())
app.use(bodyParser.urlencoded())
app.set(‘views’, path.join(__dirname,’views’));
app.get(‘/’, function(req,res){ res.render(‘survey.pug’,{products:products})
});
app.post(‘/survey’, function(req,res){ console.log(req.body);
Application scope variables
gender
= req.body.gender
…
Request scope variables
res.render(‘surveyresult.ejs’, {products: products, surveyresults: surveyresults}) });
app.listen(3000, function () {
console.log(‘survey app listening on port 3000!’)
})
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Page 4

Several Issues
– There is a single JS file with all settings and route methods
– Large application will have many route methods and some are related
– Modular controller and route mappings
– Data sharing
– Application scope variable
– Request scope variable – Session scope variable
– We don’t have separated model yet!
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Application folder structure
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Page 6

CommonsJS module standard
– A file-based module system to solve JavaScript single global namespace issue
– Each file is its own module
– Three key components:
– requires(): this method is used to load the module into the current code
• Eg: require(express)
– exports: this object is contained in each module and allows you to
expose piece of your code when the module is loaded.
– module: refers to the current module definition (metadata).
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Writing our own module
var ;
module.exports.sayHello=function(){ console.log(message);
} exports.sayBye=function(){
console.log(“Bye”)
}
message = ‘Hello’
hello.js
Hello_client.js
var hello = require(‘./hello’); hello.sayHello() hello.sayBye()
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Writing our own module
var ;
module.exports.sayHello=function(){ console.log(message);
} exports.sayBye=function(){
console.log(“Bye”) }
message = ‘Hello’
hello.js
module.exports and exports are equivalent, both referring to the object exposed by the module
We can expose many methods by defining them as properties of the module.exports object.
Hello_client.js
var hello = require(‘./hello’); hello.sayHello()
hello.sayBye()
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Calling require(…) in the client code would return the object. Our hello which has exposed two methods
modules.exports

Writing Controller(s)
survey.server.controller.js
var express = require(‘express’)
module.exports.showForm=function(req,res){ products = req.app.locals.products res.render(‘survey.pug’,{products:products})
}
module.exports.showResult=function(req,res){ console.log(req.body);
gender = req.body.gender
productidx = req.body.vote;
products = req.app.locals.products; surveyresults = req.app.locals.surveyresults; if (gender == 0)
surveyresults.mp[productidx]++;
else
res.render(‘surveyresult.ejs ‘, {products: products, surveyresults: surveyresults})
This controller module exposes two methods: showForm is used for displaying the form;
showReulsult is used for showing the results
The methods are not mapped to URL yet
req.app.locals is used to share application scope variables
Each request object has a reference to the current running express application: req.app
app.locals is used to store properties that are local variables within the application (application scope data)
}
surveyresults.fp[productidx]++;
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Page 11

Mapping Controller to URL
survey.server.routes.js
var express = require(‘express’)
var controller =
require(‘../controllers/survey.server.controller’)
var router = express.Router()
module.exports =
router.get(‘/’, controller.showForm)
router.post(‘/survey’, controller.showResult)
router
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Mapping Controller to URL
survey.server.routes.js
var express = require(‘express’)
var controller = require(‘../controllers/survey.server.controller’) var
() ()
module.exports =
router =
express.Router()
router.get
‘/’, controller.showForm
router.post
‘/survey’, controller.showResult
router
server.js
var express = require(‘express’);
var path = require(‘path’)
var bodyParser = require(‘body-parser’);
var survey = require(‘../routes/survey.server.routes’)
var app = express()
app.locals.products=[‘iphone 7’, ‘huawei p9’, ‘Pixel XL’, ‘Samsung S7’] app.locals.surveyresults = {
fp:[0,0,0,0], mp:[0,0,0,0] }
app.set(‘views’, path.join(__dirname,‘/app/views’)); app.use(express.static(path.join(__dirname, ‘public’))); app.use(bodyParser.json()) %to parse json data from the request app.use(bodyParser.urlencoded())
app.use(‘/survey’, survey) app.listen(3000, function () {
console.log(‘survey app listening on port 3000!’)
})
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Mapping Controller to URL
survey.server.routes.js
var express = require(‘express’)
var controller = require(‘../controllers/survey.server.controller’) var
() ()
module.exports =
router =
express.Router()
router.get
‘/’, controller.showForm
router.post
‘/survey’, controller.showResult
router
var express = require(‘express’);
var path = require(‘path’)
var bodyParser = require(‘body-parser’);
var survey = require(‘../routes/survey.server.routes’)
server.js
Set the two application scope variables
var app = express()
app.locals.products=[‘iphone 7’, ‘huawei p9’, ‘Pixel XL’, ‘Samsung S7’] app.locals.surveyresults = {
fp:[0,0,0,0], mp:[0,0,0,0]
}
app.set(‘views’, path.join(__dirname,‘/app/views’)); app.use(express.static(path.join(__dirname, ‘public’))); app.use(bodyParser.json()) %to parse json data from the request app.use(bodyParser.urlencoded())
app.use(‘/survey’, survey) app.listen(3000, function () {
console.log(‘survey app listening on port 3000!’)
})
– Get request send to /survey will display the form
– Post request send to /survey/survey will show the result
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Survey Web Application – MVC
Web Browser
HTTP responses
Forward requests to appropriate controller
Read/write data
Models
Database
View (Templates)
Model and Database implementation will be covered in future lectures
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Routes
Controller
Application/Web Server
DB Server

Outline
– Implementing MVC basics
– Application Folder Structure – CommonsJS modules
– Controller and Routers
– Session Management
– Database Layer
– Introduction to NoSQL
– Introduction to MongoDB
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COMP5347 Web Application Development
Page 17

Variable Scopes
– Application scope data is available through out the application
– Request scope data is available just to components handling the
current request (controller, view, model)
– Session scope data is available across multiple related requests
– Login to a web mail server
– e-commerce website with default session for until inactivity
– Session management – implemented as middleware function in module express-session
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Page 18

Session
– Session is a mechanism to associate a series of requests coming from a client
• A conversational state between the client and the server
– HTTP is stateless
– By default, each request is a session!
– To maintain a conversational state
• • •
A server needs to remember what has been going on for EACH client A client needs to send some data to identify self
Also a mechanism to control the start/end of a session
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Page 19

How does session work in general
– Client sends the first request
– The server creates an ID for the client and a session object to store session
data
– A server can maintain many sessions simultaneously (identified by ID)
– The server executes predefined business logic for that request and sends back the response together with the ID to the client
– The client stores the ID and associates it with the server
– A client may maintain many sessions with different servers simultaneously,
hence it is important to remember which ID belongs to which server
– When the client sends a second request to this server, it attaches the ID with the request
– The server extracts the ID and use it to find the session data associated with this particular client and make it available to the current request
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Page 20

On the server side
– How can server remembers client state?
– An object to hold conversational state across multiple requests from the
same client identified by a key or ID.
– It stays for an entire session with a specific client
– We can use it to store everything about a particular client.
– Stay in memory mostly but can be persisted in a database
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Page 21

Where does clients stores the ID?
– A cookie is a small piece of information stored on a client’s computer by the browser
– Each browser has its own way to store cookies either in a text file or in a lightweight database
– Each browser manages its own cookies.
– Since a browser stores cookies from various websites, it also needs a way to
identify cookie for a particular site.
– Cookies are identified by {name, domain, path}
– The following are two cookies from different domains
cookie 1
name = connect.id
value = s%3AKTObttJqW0k6aVrHB domain = localhost
path = /
cookie 2
name = name
value = Joe
domain = web.it.usyd.edu.au path = /~comp5347/doc/
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Associate web sites/pages and Cookies
– Browser would associate/send all cookies in the URL scope:
• cookie-domain is domain-suffix of URL-domain, and • cookie-path is prefix of URL-path
– An example
• Page http://web.cs.usyd.edu.au/~comp5347/doc/cookie.html will have
cookie 2 and 3, cookie 1 is not associated with this page
cookie 1
name = name
value = Paul
domain = web.it.usyd.edu.au path = /~info5010/comp5347/
cookie 2
name = name
value = Joe
domain = web.cs.usyd.edu.au path = /~comp5347/doc/
cookie 3
name = _utma
value = 223117855… domain = usyd.edu.au path = /
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express-session
– Express application’s session management is implemented as middleware function in module express-session
– Module express-session uses cookie based session management where a small cookie is created to store session id.
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Page 24

Session-aware survey
– Requirements: to ensure that a user cannot vote more than once in a certain period of time ‘using the same browser’.
– Simplesolution:
– Add a session scope variable vote to store a user’s previous vote
– Submit bottom→check if variable vote exists, if true, discard the current vote; else, set the variable to the current vote in session scope and update the results
– Session scope (object) is accessible to all request as: req.session
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Page 25

Session-aware survey
surveysession.server.controller.js
var express = require(‘express’)
module.exports.showForm=function(req,res){
products = req.app.locals.products res.render(‘surveysession.pug’,{products:products})
}
module.exports.showResult=function(req,res){ gender = req.body.gender
productidx = req.body.vote;
products = req.app.locals.products; surveyresults = req.app.locals.surveyresults; sess=req.session;
if (“vote” in sess)
res.render(‘surveysessionresult.pug’, {products: products, surveyresults:
surveyresults})
else{
sess.vote = productidx; gender = req.body.gender productidx = req.body.vote; if (gender == 0)
surveyresults.mp[productidx]++;
else
surveyresults.fp[productidx]++;
res.render(‘surveysessionresult.pug’, {products: products, surveyresults: surveyresults})
} }
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Page 26

Routes and server.js
surveysession.server.routes.js
var express = require(‘express’)
var router = express.Router()
var controller = require(‘../controllers/surveysession.server.controller’)
router.get(‘/’, controller.showForm) router.post(‘/survey’, controller.showResult) module.exports = router
server.js
var express = require(‘express’);
var path = require(‘path’)
var bodyParser = require(‘body-parser’); var session = require(‘express-session’);
var surveysession = require(‘./routes/surveysession.server.routes’) var
‘ 7’, ‘huawei p9’, ‘Pixel XL’, ‘Samsung S7’] fp:[0,0,0,0],mp:[0,0,0,0]}
app = express()
app.locals.products=[
iphone
app.locals.surveyresults
={
app.set
‘views’, path.join(__dirname
‘views’));
app.use
express.static
(
path.join(__dirname, ‘public’)));
app.use
bodyParser.json())
app.use
bodyParser.urlencoded())
app.use(session({secret:
‘
ssshhhhh
app.use
(
‘/session’
,
surveysession
app.listen(3000, function
() {
(, (
(
(
‘,cookie:{maxAge:600000}})); )
console.log(‘survey app listening on port 3000!’) })
The session will expire in 10 minutes
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Cookies sent by server
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Outline
– Implementing MVC basics
– Application Folder Structure – CommonsJS modules
– Controller and Routers
– Session Management – Database Layer
– Introduction to NoSQL
– Introduction to MongoDB
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COMP5347 Web Application Development
Page 29

NoSQL Brief Introduction
– NoSQL encompasses the general trend of a new generation of database servers
– Challenges of traditional SQL databases
– Scalability,flexibleschema,objectrelationalmismatch,etc
– Broad categories of NoSQL systems – DocumentStorage(e.g.MongoDB)
– Key-ValueStorage
– ColumnbasedStorage – Graphdatabase
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Page 30

Document Storage and MongoDB
– Document storage system based on self describing documents – Entity stored as a document (record (row) in typical SQL0
– Twodominantformats
• XML
• JSON (JavaScript Object Notation)
Invoice _1= { customer: {name: “John”, address: “Sydney”}, product: { code: “123”, quantity: 2}
}
Invoice _2= { customer: {name: “Smith”, address: “Melbourne”}, product: { code: “xyz”, quantity: 20},
delivery: “express” }
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JSON Data Format
– JSON (JavaScript Object Notation): represent JavaScript objects as strings
– Introduced in 1999 as an alternative to XML for data exchange
– JSON object: a list of property names and values contained in curly braces:
{ propertyName1 : value1, propertyName2 : value2 }
– Arrays represented with square brackets [ value1, value2, value3 ]
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Page 32

Matching Terms in SQL and MongoDB
SQL
MongoDB
Database
Database
Table
Collection
Index
Index
Row
BSON* document
Column
BSON field
Primary key
_id field
Join
Embedding and referencing $lookup in aggregation (since 3.2)
*Binary JSON
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Page 33

MongoDB Document Model – Example
TFN
Name
Email
age
12345
Joe Smith
joe@gmail.com
30
54321
Mary Sharp
mary@gmail.com
27
{ _id: 12345,
name: “Joe Smith”, email: “joe@gmail.com”, age: 30
}
{ _id: 54321,
name: “Mary Sharp”, email: “mary@gmail.com”, age: 27
}
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MongoDB Document Model – Example
users table in RDBMS
Column name is part of schema
two rows
TFN
Name
Email
age
12345
Joe Smith
joe@gmail.com
30
54321
Mary Sharp
mary@gmail.com
27
{ _id: 12345,
name: “Joe Smith”, email: “joe@gmail.com”, age: 30
}
{ _id: 54321,
name: “Mary Sharp”, email: “mary@gmail.com”, age: 27
}
Field name is part of data
two documents
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Page 35

Native Support for Array
{ _id: 12345,
name: “Joe Smith”,
emails: [“joe@gmail.com”, “joe@ibm.com”], age: 30
}
{ _id: 54321,
name: “Mary Sharp”, email: “mary@gmail.com”, age: 27
}
TFN
Name
Email
age
12345
Joe Smith
joe@gmail.com
, joe@ibm.com ??
30
54321
Mary Sharp
mary@gmail.com
27
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Page 36

Native Support for Embedded Document
TFN
{ _id: 12345,
name: “Joe Smith”,
email: [“joe@gmail.com”, “joe@ibm.com”], age: 30
}
{ _id: 54321,
name: “Mary Sharp”, email: “mary@gmail.com”, age: 27,
address: { number: 1,
name: “cleveland street”, suburb: “chippendale”, zip: 2008
}
}
age
12345
Name
Joe Smith
Mary Sharp
Email
joe@gmail.com
30
54321
mary@gmail.com
27
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Page 37

Native Support for Embedded Document
TFN
{ _id: 12345,
name: “Joe Smith”,
email: [“joe@gmail.com”, “joe@ibm.com”], age: 30
}
{ _id: 54321,
name: “Mary Sharp”, email: “mary@gmail.com”, age: 27,
address: { number: 1,
name: “cleveland street”, suburb: “chippendale”, zip: 2008
}
}
Name
age
12345
Joe Smith
Mary Sharp
Email
joe@gmail.com
30
address
54321
mary@gmail.com
27
1 cleveland street, chippendale, NSW 2008
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Page 38

MongoDB data types
– Primitivetypes
– String,integer,boolean(true/false),double,null
– Predefined special types
– Date, object id, binary data, regular expression, timestamp,
– DB Drivers implement them in language-specific way
– The interactive shell provides constructors for all
– Array and object
– Field name is of string type with certain restrictions – “_id” is reserved for primary key
– cannot start with “$”, cannot contain “.” or null
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Page 39

MongoDB Queries
– A read query targets a specific collection
– criteria
– may include a projection to specify fields from the matching documents
– may include modifier to limit, skip, or sort the results
– A write query may create, update or delete data
– One query modifies the data of a single collection
– Update and delete query can specify query criteria
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Page 40

Read Query Example
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Read Query Example
Find documents in the users collection with age field greater than 18, sort the results in ascending order by age
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Page 42

Read Query Interface
– db.collection.find()
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Page 43

Read Query Interface
– db.collection.find()
Find at most 5 documents in the users collection with age field greater than 18, return only the name and address field of each document.
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Page 44

Read Query Interface
– db.collection.find()
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Page 45

Read Query Features
– Find data using any criteria
– Does not require indexing
– Indexing can improve performance
– JOIN is not supported!!
– Query criteria expressed as BSON document (query object)
– Individual expressed using predefined selection operator
• Eg. $lt is the operator for “less than”
– Query projection are expressed as BSON document
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Page 47

Read Query Features
SQL
MongoDB Query in Shell
select * from user
db.user.find() or db.user.find({})
select name, age from user
db.user.find({},{name:1,age:1,_id:0})
select * from user
where name = “Joe Smith”
db.user.find({name: “Joe Smith”})
select * from user where age < 30 db.user.find({age: {$lt:30}}) The University of Sydney COMP5347 Web Application Development Page 48 Querying Array field – Like querying simple type field – db.user.find({emails:“joe@gmail.com”}) – db.user.find({“emails.0”:“joe@gmail.com”}) { _id: 12345, name: “Joe Smith”, emails: [“joe@gmail.com”, “joe@ibm.com”], age: 30} { _id: 54321, name: “Mary Sharp”, email: “mary@gmail.com”, age: 27} http://docs.mongodb.org/manual/tutorial/query-documents/#arrays The University of Sydney COMP5347 Web Application Development Page 49 – Querying Embedded Document Queried as a whole, by individual field, or by combination of individual fields – db.user.find({address: {number: 1, name: “pine street”, suburb: “chippendale”, zip: 2008}}) – db.user.find({“address.suburb”:“chippendale”}) – db.user.find({address: {$elemMatch: {name: “pine street”, suburb: “chippendale”}}) { _id: 12345, name: “Joe Smith”, email: [“joe@gmail.com”, “joe@ibm.com”], age: 30, address: {number: 1, name: “pine street”, suburb: “chippendale”, zip: 2008 } } { _id: 54321, name: “Mary Sharp”, email: “mary@gmail.com”,age: 27, address: { number: 1, name: “cleveland street”,suburb: “chippendale”,zip: 2008 } } http://docs.mongodb.org/manual/tutorial/query-documents/#embedded-documents The University of Sydney COMP5347 Web Application Development Page 50 Write Query- Insert The University of Sydney COMP5347 Web Application Development Page 51 Insert a new document in users collection. Insert Example – db.user.insert({_id: 12345, name: “Joe Smith”, emails: [“joe@gmail.com”, “joe@ibm.com”],age: 30}) – db.user.insert({ _id: 54321, name: “Mary Sharp”, email: “mary@gmail.com”, age: 27, address: { number: 1, name: “cleveland street”, suburb: “chippendale”, zip: 2008}}) The University of Sydney COMP5347 Web Application Development Page 52 Insert Behavior – If the new document does not contain an “_id” field, the system will adds an “_id” field and assign a unique value to it – If the new document does contain an “_id” field, it should have a unique value The University of Sydney COMP5347 Web Application Development Page 54 Write Operation - Update Has the same effect as the following SQL: The University of Sydney COMP5347 Web Application Development Page 55 Updates operators – Modifying simple field: $set, $unset – db.user.update({_id: 12345}, {$set: {age: 29}}) – db.user.update({_id:54321}, {$unset: {email:1}}) // remove the field { _id: 12345, name: “Joe Smith”, emails: [“joe@gmail.com”, “joe@ibm.com”], age: 30} { _id: 54321, name: “Mary Sharp”, email: “mary@gmail.com”, age: 27} http://www.mongodb.org/display/DOCS/Updating The University of Sydney Page 56 – Updates operators Modifying array elements: $push, $pushAll, $pull, $pullAll – db.user.update({_id: 12345}, {$push: {emails: “joe@hotmail.com”}}) – db.user.update({_id: 54321}, {$pushAll: {emails: [“mary@gmail.com”, “mary@microsoft.com”]}}) – db.user.update({_id: 12345}, {$pull: {emails: “joe@ibm.com”}}) { _id: 12345, name: “Joe Smith”, emails: [“joe@gmail.com”, “joe@ibm.com”], age: 30} { _id: 54321, name: “Mary Sharp”, email: “mary@gmail.com”, age: 27} http://www.mongodb.org/display/DOCS/Updating The University of Sydney Page 57 Updates operators – Modifying simple field: $set, $unset – db.user.update({_id: 12345}, {$set: {age: 29}}) – db.user.update({_id:54321}, {$unset: {email:1}}) // remove the field – Modifying array elements: $push, $pushAll, $pull, $pullAll – db.user.update({_id:12345},{$push:{emails:“joe@hotmail.com”}}) – db.user.update({_id:54321}, {$pushAll: {emails: [“mary@gmail.com”, “mary@microsoft.com”]}}) – db.user.update({_id:12345},{$pull:{emails:“joe@ibm.com”}}) { _id: 12345, name: “Joe Smith”, emails: [“joe@gmail.com”, “joe@ibm.com”], age: 30} { _id: 54321, name: “Mary Sharp”, email: “mary@gmail.com”, age: 27} { _id: 12345, name: “Joe Smith”, emails: [“joe@gmail.com”, “joe@hotmail.com”], age: 29} { _id: 54321, name: “Mary Sharp”, emails: [“mary@gmail.com”, “mary@microsoft.com”] age: 27} http://www.mongodb.org/display/DOCS/Updating The University of Sydney Page 58 Write Operation - Delete – db.user.remove(); – Remove all documents in user collection – db.user.remove({_id: 12345}) – Remove document with a particular id from user collection The University of Sydney COMP5347 Web Application Development Page 59 Aggregation – Simple and relatively standard data analytics can be achieved by aggregation – Grouping, summing up value, counting, sorting, etc – Running on the DB engine instead of application layer – Several options – Aggregation Pipeline – MapReduce • JavaScriptfunctions • Performance • Customizedaggregations The University of Sydney COMP5347 Web Application Development Page 60 – Aggregation Pipeline Consists of multiple stages – Specified using pipeline operators (e.g., $match, $group, $sort and so on) • Similar to SQL’s WHERE, GROUP BY, SORT BY etc • Each stage is expressed as an object enclosed by curly bracket – Various expressions can be specified in each stage • To filter documents or to perform simple calculation on a document – $substr, $size, etc, ... – $group stage can specify accumulators to perform calculation on documents with the same group key The University of Sydney COMP5347 Web Application Development Page 61 Aggregation Pipeline – Format db.collection.aggregate( [ { pipeline operator: {expression/accumulator,..., expression/accumulator} }, { pipeline operator: {expression/accumulator,..., expression/accumulator} }, ... ]) The University of Sydney COMP5347 Web Application Development Page 62 Aggregation Example The University of Sydney COMP5347 Web Application Development Page 63 Aggregation Example The University of Sydney COMP5347 Web Application Development Page 64 select cust_id as _id, SUM(amount) as total from orders where status = “A” group by cust_id Aggregation Behaviour – Operates on a single collection (before 3.2) – Join can be performed using a particular operator $lookup – Logically passes the entire collection into the pipeline – Early filtering can improve the performance – $match and $sort operators are able to use index if placed at the beginning of the pipeline The University of Sydney COMP5347 Web Application Development Page 65 Resources – Haviv, Amos Q, MEAN Web Development – E-book, accessible from USYD library – Chapter 4 and 5 – MongoDB online documents: – MongoDB CRUD Operations • http://docs.mongodb.org/manual/core/crud-introduction/ – MongoDB Aggregation • http://docs.mongodb.org/manual/core/aggregation-introduction/ The University of Sydney COMP5347 Web Application Development Page 66 Week 6 Tutorial: Node.js MVC Application Finalize groups on Canvas and Github Week 7 Lecture: Connecting to MongoDB The University of Sydney Page 67

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