WEBVTT

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 Hello, everyone, and welcome to the
 first section of this course.

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 In this video, we're going to be getting
 a formal introduction to web

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 services. So if this is your first
 time hearing about web services or

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 you're not to show what they are and
 how they work, this section is for

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 you and this video in particular is
 going to answer those questions.

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 So to kick things off, what is a web
 service or what are web services?

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 Web services are software components
 designed to facilitate communication

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 and data exchange between different applications
 or systems over the internet.

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 So the primary thing or the primary
 reason as to why they were created

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 was to facilitate communication.

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 So what were they facilitating or between
 what systems were they facilitating

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 communication with?

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 Well, in order to answer that question,
 we firstly need to understand

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 where we have come from or
 why they were created.

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 So web services were essentially created.


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 Now I'm using a very basic example here.

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 Web services or APIs were created so
 that two computers can communicate

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 with one another and understand one
 another without the need for human

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 interaction. So in the context of web
 services specifically, given that

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 they are designed to be run on the
 web, think of a very basic example

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 where, let's take a look at a web application
 like a simple website that

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 allows users to log in, create a blog
 post or something like WordPress,

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 right? WordPress and the way it is designed
 as a web application, it is

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 designed to be a web application to
 be used by human beings, which means

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 it has a user interface and everything
 makes sense to a human being.

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 However, when we bring, let's say,
 another server into the picture and

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 let's say we want the WordPress site
 to communicate with that other web

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 server for whatever reason, let's say
 they wanted to communicate with

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 one another. How would that other web
 server interact with the WordPress

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 web application or website?

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 That's really the actual primary question
 behind the reason as to why

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 web services were created because remember,
 computers do not know what

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 a UI is. They cannot interact with a UI.

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 They just, at least in the case of the
 WordPress server, they just know

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 how to handle specific action.

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 When you click a button, again, the web
 server doesn't know that you have

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 actually visually clicked a button.

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 What they're doing is processing
 the request that they received.

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 That's why web services were created.

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 They were created so that two computers
 can communicate with one another.

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 In the case of APIs, APIs were created
 so that two applications specifically

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 could communicate and interact with one
 another without the need or without

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 the use of human beings
 or user interfaces.

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 That's why whenever you interact with
 an API and try and open up an API

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 endpoint within your browser, you
 just either get XML or JSON.

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 If you study the output, you'll see
 that only the essential information

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 or specific information is being
 sent through an API endpoint.

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 The bottom line is that they allow disparate
 applications or systems to

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 work together, even if they are developed
 on different platforms using

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 different programming languages
 or running on different servers.

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 I'll explain the differences between
 web application and a web service

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 and an API later on in this video.

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 But going again deeper into the definition
 of web services and how they

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 work, they are usually intended to
 facilitate the integration between

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 applications. An example here is that
 application A utilizes features

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 that are only implemented or only
 available in application B.

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 That's a very common example
 or an actual use case.

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 Secondly, separation within
 an application.

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 Think of the actual functionality of
 an application being broken down

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 into the front end and the back end but
 also including another component.

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 Front end scripts that use web service
 functionality to dynamically update

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 the content. That's another example.

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 You don't see it quite often.

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 If you do see an API that's built within
 the overall architecture of a

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 web application, they're typically there
 to facilitate processing of specific

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 requests like financial transactions
 or maybe even generating OTP codes,

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 etc. These are two examples of what
 web services are usually intended

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 to facilitate or why they were created
 and how they're typically used.

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 That brings us to the penultimate
 slide within this video.

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 That is what is the difference between
 a web service and a web application.

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 Let's understand web services
 now as clearly as possible.

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 Web services are designed to facilitate
 communication and data exchange

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 between different software systems over
 the internet or different systems

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 altogether. They provide a standardized
 way for different applications

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 to interact with each other using protocols
 like SOAP which is the simple

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 object access protocol or REST which
 you should be familiar with if you

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 have ever interacted with an API.

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 REST is typically what you'll see now.

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 And web services are typically used
 for machine to machine communication

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 and are not meant for direct
 human interaction.

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 So that's why they're a little
 bit difficult to understand.

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 Whenever you open up an API endpoint,
 you might be a little bit confused.

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 And the reason you're confused is because
 that's the interface that is

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 being used by the two web applications
 or the two systems.

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 It is not meant to be understood
 by human beings.

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 Now, that's where I come into play in
 the form of this course to actually

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 show you how to understand what's
 going on behind the scenes.

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 So while naturally speaking, you cannot
 understand what exactly is going

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 on or the communication between a web
 service and a web application or

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 you cannot understand the schema being
 used between two different systems

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 communicating with each other through
 a web service or an API, there's

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 many ways you can sort of decipher that.

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 So in terms of web applications, you
 should already be familiar with what

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 they are and how they work.

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 But web applications are software programs
 that are accessed through a

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 web browser and they're designed to
 perform specific tasks or provide

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 services directly to end users or
 clients which are human beings.

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 And they are meant for human interaction
 and can range from simple websites

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 to complex web-based applications like
 email clients, social media platforms

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 or online shopping sites.

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 So you can see the difference here in terms
 of the architectural and functional

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 perspective that web services are essentially
 extending or giving other

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 systems or applications the ability
 to communicate with your web app and

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 to communicate effectively because before
 web services or APIs, two different

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 web applications could not communicate
 with one another especially in

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 a standardized structured way that both
 of those systems could understand

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 in terms of requests and responses.

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 So that brings us to this table here
 that pretty much distinguishes web

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 services from web applications.

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 And on the left hand side, the absolute
 left, you can see the different

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 aspects and then on the right hand
 side, you can see the split or the

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 actual aspect definition for each.

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 So in the case of web services, the
 primary purpose of a web service is

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 to facilitate data exchange
 between applications.

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 In the case of web applications, it's
 to provide services or perform tasks

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 directly for end users.

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 In terms of user interaction, in web
 services, there is no user interface

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 and it is meant for machine
 to machine communication.

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 In the case of web applications, they
 have a user friendly interface for

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 human interaction.

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 Typically speaking, of course, you will
 find some really badly designed

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 websites out there, but typically speaking,
 they have a UI user friendly

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 interface. And in terms of data exchange,
 in the case of web services,

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 there's a exchange of structured
 data between applications.

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 In the case of web applications, it
 involves user data input processing

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 and result presentation.

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 So the bottom line is because we have
 five senses, when we send something

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 in or we type something into a website,
 we want to see a response.

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 And that's why web applications are
 designed the way they are so that

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 when you put in your successful and
 you want a representation of that

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 fact, but with computers, they don't
 need that or with two applications

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 communicating with one another,
 they don't need that.

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 They pretty much just need to see the,
 for example, the HTTP response

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 with a 200 status code saying, yep,
 authentication was successful, you

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 can proceed. So in that form or in
 that way of thinking, I really like

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 how computers communicate
 with one another.

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 It's very effective.

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 You then have the communication protocol.


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 So in the case of web services, you
 know, web services utilize protocols

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 like SOAP REST, XML RPC or JSON RPC
 will be covering these in the next

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 set of videos. And in the case of web
 applications, as you know, they

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 utilize primarily utilize HTTP
 or HTTPS for communication.

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 In terms of the security focus, in
 the case of web services, there's a

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 focus on securing data during transmission
 and access control.

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 So essentially controlling
 access to an endpoint.

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 And then of course, securing
 the data in transit.

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 In the case of web applications, as you
 know, with all the courses within

0:10:35.240000 --> 0:10:39.020000
 this learning path, there's, you know,
 broader security aspects that need

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 to be taken into account, including
 authentication, authorization, data

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 validation and protection against other
 types of web based vulnerabilities.

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 In terms of examples, in the case of web
 services, you can think of payment

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 gateways like the PayPal, the PayPal
 API or whether data services.

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 In the case of web applications, I think
 you know what some common examples

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 are, you know, online banking, e-commerce,
 personal blog, emails, social

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 networking, so on and so forth.

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 So those are the differences between
 web services and web applications.

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 Now, coming into some key characteristics
 of web services, there are a

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 couple that you need to be aware of.

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 Firstly, the interoperability.

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 So web services promote interoperability
 by providing a standardized way

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 for applications to communicate.

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 They rely on open standards like HTTP,
 XML, SOAP, REST and JSON to ensure

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 compatibility. So what does this mean?

0:11:36.960000 --> 0:11:42.060000
 It means that one of the key characteristics
 here is the fact that APIs

0:11:42.060000 --> 0:11:46.240000
 don't have an issue of translation.

0:11:46.240000 --> 0:11:49.920000
 Let's say if you wanted two applications
 to communicate with one another,

0:11:49.920000 --> 0:11:55.040000
 they are standardized protocols or frameworks
 designed to facilitate this.

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 So for example, when you, let's say when
 you are talking to another developer

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 and you have two web applications
 that you'd like to integrate.

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 So think of a good example here is
 think of your online banking portal

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 and QuickBooks. So QuickBooks allows
 you to integrate your online bank

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 into QuickBooks so that you can view
 your recent transactions, etc.

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 That integration is done through
 the form of an API.

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 Now how did the developers of your,
 how did the developers of your bank,

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 of your bank's sure that QuickBooks
 could communicate with that API, you

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 know, with the actual
 online banking portal?

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 They did that through the form of an
 API or a web service and the API

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 or web service was created or implemented
 using one of these standards

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 or frameworks. So it could be, it could
 have been a REST API, it could

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 have been a SOAP API.

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 And what that means is that QuickBooks
 at that point only needs to know

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 that and they it works.

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 You just, from that point on the bank
 just needs to tell QuickBooks how

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 the API works in terms of requests
 and response, you know, and various

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 parameters. And they typically will
 provide, you know, the actual API

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 documentation or in the case of SOAP
 based web services, they'll provide

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 the WSDL, right, which essentially tells
 human beings firstly, but also

0:13:32.320000 --> 0:13:37.920000
 computers, how the web service operates
 and what it can process in terms

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 of, you know, requests.

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 Secondly, you know, web services and
 APIs, generally speaking our platform

0:13:44.180000 --> 0:13:48.400000
 agnostic. So they are not tied to a specific
 operating system or programming

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 language and they can be developed in
 various technologies, making them

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 versatile and accessible.

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 So you know that we have operating
 specific APIs, we have web APIs or

0:13:58.740000 --> 0:14:02.540000
 web services and they're not really
 tied to, you know, either running

0:14:02.540000 --> 0:14:05.860000
 on Windows or Linux or on PHP or Python.

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 They pretty much are outside of that
 scope and do not require you to,

0:14:09.640000 --> 0:14:14.620000
 you know, factor in usability on
 a different operating system.

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 Moving forward, of course,
 loose coupling.

0:14:17.620000 --> 0:14:21.780000
 So web services allow for loosely coupled
 interactions between systems.

0:14:21.780000 --> 0:14:25.920000
 This means that changes in one system's
 implementation do not necessarily

0:14:25.920000 --> 0:14:28.420000
 disrupt the functionality
 of the other systems.

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 What this means is that let's say QuickBooks
 or the only in the example

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 earlier, let's say your banking portal,
 you know, gets an update in terms

0:14:38.120000 --> 0:14:41.760000
 of adding new features or stuff like
 that, that really will not affect,

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 you know, will not affect the actual
 API or the communication between

0:14:46.860000 --> 0:14:51.860000
 your banking portal and QuickBooks because
 of how, you know, loosely coupled

0:14:51.860000 --> 0:14:54.300000
 APIs or web services are.

0:14:54.300000 --> 0:14:56.160000
 And then of course you have
 location independent.

0:14:56.160000 --> 0:15:00.720000
 So web services operate on the, over
 the internet, making them location

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 independent. They can be hosted on different
 servers and can be accessed

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 from anywhere with an
 internet connection.

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 And they can also be hosted locally
 on your local area network.

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 So they're very, very flexible with
 that, you know, if you take that or

0:15:14.660000 --> 0:15:16.800000
 if you look at it from that perspective.

0:15:16.800000 --> 0:15:19.240000
 So that brings us to the
 end of this video.

0:15:19.240000 --> 0:15:22.120000
 Hopefully you got that formal
 introduction you are after.

0:15:22.120000 --> 0:15:25.180000
 As I said, I'll be making
 it clearer as we progress.

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 And that's always my objective here.

0:15:27.220000 --> 0:15:29.760000
 In the beginning things are
 still a little bit fuzzy.

0:15:29.760000 --> 0:15:33.660000
 But once you get to the end or at least
 to the end of this course, I'm

0:15:33.660000 --> 0:15:37.220000
 sure you'll understand web services
 and APIs much better.

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 With that being said, that's going
 to be it for this video.

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 And I'll be seeing you in the next video.