0:00	foreign
0:07	welcome back in this presentation we are
0:10	going to see about an important
0:12	architecture for databases the
0:14	three-tier architecture by waiting let's
0:17	directly step into the topic of the day
0:20	the three-tier architecture as the name
0:23	says that there are three levels three
0:25	tiers what are they the first level is
0:28	the client level the second level is the
0:31	application Level or the web server
0:33	level and the third level is the
0:35	database server level so the client
0:37	level is actually the GUI the graphical
0:40	user interface or web interface level
0:42	the application server level or the web
0:44	server level deals with the application
0:46	programs and web pages and then the
0:49	third level the database server level
0:51	which deals with the actual database
0:53	management system now you may be asking
0:56	me a question why do we need three tiers
0:58	why not two tiers like simply client and
1:02	server say the traditional client server
1:04	architecture involves two tiers client
1:06	and server but when we talk about
1:08	databases the web pages remote access we
1:12	certainly need three tiers we will see
1:15	that now so when we talk about the
1:17	three-tier architecture this is actually
1:20	the predominant software architecture
1:22	for the client server applications say
1:25	for example I want to do a fund transfer
1:27	from my account to my friends account to
1:30	do that I need not go to the bank rather
1:32	I can simply open the internet banking
1:34	page on my browser of my computer or I
1:38	can use the banking app from my mobile
1:39	to do the fund transfer whatsoever the
1:43	front end that we are interacting with
1:45	the banking server it may be a web
1:47	interface when we access through a
1:49	browser or if it is a mobile interface
1:51	the page that we are accessing on our
1:54	mobile phone through the application
1:55	this is actually the first level or the
1:58	first year the client year this is is
2:00	the top tier and all the business logic
2:03	are done in the second tier that is the
2:05	application Level tier and the actual
2:08	data storage is at the third year the
2:10	data based year which is the physical
2:12	tier or the bottom most tier when we
2:15	talk about distributed systems or remote
2:17	access then three-tier architecture is
2:20	the predominant software architecture
2:22	for client server applications and as
2:25	the name suggests there are three
2:26	logical and physical tiers we can see
2:29	these three are the tiers and these
2:31	tiers are logically and physically
2:34	separated and what's the advantage of
2:36	having three tiers
2:38	each tier runs on its own infrastructure
2:41	so this year the client here or the web
2:44	interface here or the GUI tier will have
2:47	its own infrastructure application
2:49	server or web server will have its own
2:51	infrastructure and the database tier
2:53	will have its own infrastructure and
2:55	that's what this point says that each
2:57	tier runs on its own infrastructure and
3:00	since they have their own infrastructure
3:02
these tiers can be developed
3:05
simultaneously so they are going to
3:07
interact with each other of course they
3:10
can be developed simultaneously because
3:12
each tier runs on its own infrastructure
3:14
at the same time another advantage of
3:17
having tiers is that these tiers can be
3:20
scaled and updated individually so I
3:23
hope now you got the details about the
3:25
three tiers and we can also give names
3:27
for these tiers as the presentation tier
3:29
which is the client tier the application
3:32
tier which is the middle tier and data
3:34
tier which is the bottom most here the
3:36
physical storage of the database
3:38
and the main advantages of having all
3:41
these tiers are the faster development
3:43
because they have their own
3:45
infrastructure and they can be developed
3:47
simultaneously and these stairs can also
3:49
be scaled and updated so we get improved
3:52
scalability reliability and security so
3:56
we are done with the basics of
3:57
three-tiered architecture let's see each
4:00
tier one by one let's focus on the first
4:03
tier
4:04
what's the first year the topmost tier
4:07
the client tier or the presentation tier
4:10
in other words it is also called as the
4:12
front end because the user is
4:13
interacting with that year right if you
4:15
want to access your banking server you
4:17
may access from your browser or from
4:19
your mobile app so that's the front end
4:22
that's actually the tier that user is
4:24
interacting with and that's why this
4:26
tier is called as front-end and as the
4:28
name suggests this is the top level tier
4:30
where the user is going to interact with
4:32
the application or the server and what
4:35
will be there in this tier the user
4:37
interface say you may be accessing your
4:39
data which is actually stored in the
4:41
database in a web interface or in a GUI
4:44
environment so simply it's an user
4:46
interface and that's what I told you in
4:48
the example analogy you may access your
4:50
banking server from your mobile
4:52
application or from a web browser so in
4:54
either cases we need user interfaces
4:57
which is simply referred as UI and this
4:59
year we know this is the top tier and
5:02
this is going to interact with the next
5:03
tier which is the application tier and
5:06
what's there in the application tier we
5:08
will see that in the next slide so from
5:10
this what we are understanding is the
5:12
top tier the presentation tier or the
5:14
client here is interacting with the next
5:16
tier the application tier where the
5:18
business logic are implemented
5:21
and we know this is the user interface
5:23
which collects and displays the
5:24
information say for example if you want
5:26
to see what's your account balance
5:28
obviously your balance is displayed on
5:30
the presentation screen right it may be
5:32
a Mobile screen or it may be a web
5:34
interface so display is also done at the
5:37
same time if you want to do one transfer
5:39
from there you are giving the
5:40
information like how much amount to
5:42
which account to be transferred so your
5:44
presentation tier not only displays the
5:46
data it also collects the data and
5:48
that's why this tier deals with
5:50
collecting and displaying of the
5:52
information and we also have desktop
5:54
applications or even GUI for doing this
5:59
HTML hypertext markup language CSS
6:03
JavaScript Etc so we can develop the
6:05
front-end application using these
6:07
Technologies so we are done with the top
6:10
level tier the presentation tier or the
6:12
front end or the client tier the next
6:14
tier that we are going to address is the
6:17
application tier we know basically there
6:20
are three tiers and now we are going to
6:21
focus on the second tier the application
6:24
server or the web server and what's the
6:27
job of this tier we know the drop of the
6:29
front end is to collect and display the
6:31
information where the logic is actually
6:33
applied the transaction logic say if you
6:36
want to transfer fund from your account
6:38
to your friend's account that logic
6:40
where it is implemented it's actually
6:42
implemented in the application Level
6:44
that is the business logic level so this
6:47
level or this tier deals with the logic
6:49
or the middleware tier activities so
6:52
this is the middleware tier and actually
6:54
this is the heart of the application
6:56
because the business logic and the
6:57
business rules and the information are
7:00
processed in this tier only at the same
7:02
time the business logic and the business
7:04
rules are also implemented at this level
7:06
and we know this year the presentation
7:08
tier deals with the collection and
7:11
display of data but the logic is
7:13
actually applied here in case the logic
7:15
involves addition or deletion or
7:17
updation of the data all these needs to
7:19
be done in the data tier where the data
7:22
is actually stored in the database which
7:23
is the physical tier so this tier is
7:25
directly interacting with the bottom
7:27
most tier which is the physical tier or
7:30
the data tier or simply the database
7:32
server and what are all the technologies
7:33
that are there in this tier python Java
7:36
Perl PHP Ruby Etc
7:38
before we move on we need to understand
7:40
how this application tier interacts with
7:43
the data tier it's through the API calls
7:46
so the communication between the
7:48
application tier and the data tier is
7:50
through the API calls the application
7:52
programming interface calls we know
7:54
there are applications for doing all the
7:56
activities that we wanted using these
7:58
Technologies and these Technologies has
8:01
built-in API interfaces so that they can
8:04
directly interact with the database
8:05
server so we are done with the second
8:08
tier the application server or web
8:10
server tier let's now move on to the
8:13
next tier the bottom most tier which is
8:15
actually the data based here and this
8:18
subject is actually the database
8:20
management system and we are talking
8:22
about this subject elaborately in this
8:25
playlist and we are going to focus on
8:27
what's happening in this tier and we
8:30
know the presentation tier is the front
8:32
end and this is the application tier or
8:34
the business logic or the business rules
8:36
and what about the last tier the back
8:39
end where the data are actually stored
8:42
so this is the back end tier or the
8:44
backend level or simply the database
8:46
server resides in this level we have the
8:49
physical database the physical storage
8:51
everything in this tier only so as the
8:53
name suggests this is the data tier or
8:56
the database tier or simply the backend
8:58
and here only the data are actually
9:01	stored and managed which is actually the
9:03	job of dbms and at the same time this
9:06	tier is having interaction with the
9:09	application tier and not directly with
9:11	the client or the presentation tier in a
9:13	three-tier architecture in a two-tier
9:15	architecture client or the presentation
9:17	tier will directly communicate with the
9:19	database here or the back end because
9:22	only two tiers are there but in this
9:24	case we are talking about three-tier
9:26	architecture so the communication
9:28	between presentation tier and data tier
9:30	are not directly possible it is possible
9:33	through the apis of the application and
9:36	what are the software tools we have the
9:38	rdbms and dbms tools rdpms Technologies
9:41	like MySQL mariadp Oracle db2 Microsoft
9:45	SQL Server postgresql
9:48	Etc are rdbms Technologies and coming to
9:51	the dbms Technologies the Cassandra
9:54	couchdb mongodb Etc are example
9:57	Technologies for dbms so we are done
10:00	with all the three tiers before we sign
10:02	out let's see the generalized dbms
10:04	three-tier architecture so the name says
10:07	that we have three tiers where we have
10:09	the database at the physical level the
10:11	bottom most level and this is called as
10:13	the internal level because the data are
10:15	actually stored at this level and we
10:17	have the business rules the second level
10:19	which is the conceptual level and we
10:22	have the upper level or the top level
10:24	which is the user level or view level we
10:27	can see that user is going to interact
10:28	with the database through this level
10:30	only and we have multiple views possible
10:33	at this level don't worry about this now
10:35	in the next presentation we are going to
10:37	exclusively focus on the various view
10:39	levels I mean view of data and that's it
10:43	guys I hope the session is informative
10:46	and thank you for watching
10:48	[Music]
10:48	[Applause]
10:50	[Music]