Video 2: Web App Definition

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来自 University of New Mexico 的课程

Web Application Development: Basic Concepts

128 个评分

University of New Mexico

Web Application Development: Basic Concepts

128 个评分

This is the first course in a Coursera Specialization track involving Web Application Architectures. This course will give you the basic background, terminology and fundamental concepts that you need to understand in order to build modern full stack web applications. A full stack web developer is familiar with each "layer" of the software technologies involved in a web application, including data modeling and database technologies, the web server environment and middleware components, network protocols, the user interface and basic visual design and user interaction concepts. In this course we will learn by doing. We will start by learning the major components of web application architectures, along with the fundamental design patterns and philosophies that are used to organize them. You will build and continually refine a fully functional full-stack web application as we progress through the modules in this course. Along the way you will be exposed to agile software development practices, numerous tools that software engineers are expected to know how to use, and a modern web application development framework. This course is also available in Spanish. To join the Spanish version, visit this page: https://www.coursera.org/learn/apliweb.

从本节课中

Module #1 - Web Applications in Context

This module sets the context for what we will study in this specialization by first providing a historical perspective on computing and web applications. Next we provide an overview of how the Internet works, and then we discuss how web applications have evolved over the past few decades. After that we’ll discuss some of the elements of modern software practice, including the typical tools that software engineers now use and the agile development practices they follow. The notion of software design patterns will introduced, and the n-tier architecture design pattern, fundamental to modern web application design, is then presented. Will also discuss a few current topics related to web application development. Finally, we will show you how to set up the software development environment you will use throughout the remainder of the courses in this.

What is a Web Application? - An Overview0:33

Video 1: Web Apps - A Model2:47

Video 2: Web App Definition5:14

Video 3: Evolution of Web Apps8:51

Video 4: Design Patterns4:58

Video 5: n-Tier Architecture6:20

与讲师见面

Greg Heileman
Professor and Associate Provost
Electrical and Computer Engineering
Manel Martínez-Ramón
Professor
Electrical and Computer Engineering

[MUSIC]

Let's now more formally define what is a Web App?

So now that we have a few terms under our belt,

we can define what we mean by a web application.

Here's a formal definition.

A web application is accessed by users via the Internet,

using a browser as the client, and consists of a collection of client and

server scripts, HTML pages, and other resources

that may be spread across multiple web servers, or through the World Wide Web.

So examples of this are web mail, online retail stores,

online banks, online auctions, Wikis, blogs, document storage.

In short it's many of the things I showed you in the opening lecture.

So it's important to understand all of the pieces of this definition.

That the app is accessed via the Internet using a browser.

And that there are many things that are happening on the server side and

that it leverages the World Wide Web.

Let's talk a little bit more about what we mean by the Web Apps and

the World Wide Web.

So when I say web, and just use the term web, I mean the World Wide Web.

In other words, a web application is an application that uses the World Wide Web.

What exactly is the World Wide Web?

Well it's a system of interlinked documents

that are accessed via the Internet using HTTP.

So the web operates on top of the Internet using HTTP.

So it's important to understand the difference between the Internet and

the World Wide Web, the World Wide Web operates on top of the Internet.

Now web page is contain hypermedia, along with hyperlinks to other web pages.

Hypermedia can be text, graphics, images, video and other multimedia content.

And it's the hyperlinks that give the web its phenomenal structure.

If you think about it, it's absolutely amazing.

Almost all of the human knowledge is contained in the structure

of the hyperlinks in the World Wide Web.

It's what makes the web useful and it's what gives it it's tremendous value.

It's amazing if you think about it.

So a Web App in summary is built on top of the World Wide Web,

one of the most amazing structure that mankind has ever built.

And the World Wide Web is built on top of the Internet,

an astonishingly complex network of computing devices.

What are the advantages of web applications?

Well, you the ubiguity and convenience of using a browsers as a client is

one of the most important advantages that you have with a web application.

Everybody has a browser running on almost any device that they own, from desktop,

to tablet to phone.

And there's inherent cross platform compatibility in today's browsers content

delivered to just about any browsers going to render in that browser nowadays.

You have an ability to update and maintain web apps without disturbing the installed

based on potentially thousands of client computers as long as you make sure that

your web app works on current generations of browsers everything will be fine.

And there's this amazing reduction in IT cost by going to a web app because of

the point that I just made.

Much easier to maintain applications

that are meant to be deployed as web applications.

Now, what are the disadvantages?

Well the user’s experience, as compared to desktop apps used to be a problem.

Now that's really not the case,

it used to be the case that you can really tell a difference between whether or

not you were on a desktop application or a web application.

Now a days it's very difficult to distinguish between the two, so

I think now a days this is not really an advantage.

But there are privacy and

security concerns associated with your data on a web app.

Anyone around the world can potentially access your application.

So if you're really after privacy and security, sometimes folks have to

build standalone apps that don't run in a networked environment.

But one of the things we want to do is leverage the World Wide Web

when we're building a web application.

So that's not much of a disadvantage, if that's your goal.

Now, from a programmer's perspective, this is probably the main disadvantage.

Web apps are difficult to develop and debug.

What I like to say is there's a lot of moving parts,

if you think about you have to be able to program at the level of a database.

At the level of middleware, you have to understand all the protocols that

are a part of the middleware, and sometimes this involves writing scripts.

And you have to understand how to write code that will display webpages properly.

So this involves understanding HTML, JavaScript, and

possibly some other programming languages.

So there's a lot of moving parts in a web application,

a lot of different programming languages you have to understand in order to make

a web application work properly.

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