Hi there. 2
Welcome back. 3
And this is the little laugh courses and books typically use simple examples to explain object oriented 4
concepts like inheritance polymorphism and deficits and so on which we're going to study in this course 5
. 6
These concepts are critical for developing well-designed applications. 7
And my belief is that explaining such important concepts using simple examples may not be that helpful 8
in truly understanding them. 9
So even after learning the concepts in practice you may not be able to apply them in a proper way so 10
to address this we're going to use it real world system as a case study to learn these concepts. 11
The system is basically a social bookmarking application that we are developing here at semantics where 12
the application is called trail dog. 13
And that's also the user of the system. 14
And we simply call it ask Chromeo are sometimes just true. 15
It doesn't pre-alpha onstage that is it is mostly used only internally by our development team as we 16
are still developing it. 17
However it is already in decent shape with some architecture and also includes advanced algorithms from 18
areas like search and data mining. 19
Yesterday will also include few features that have not yet been developed but are on alert To-Do list 20
. 21
Initially we will look at a few basic features that should help us learn some of the concepts likker 22
Rubinek or just a few more features and to build those features we need to understand more advanced 23
concepts and advanced concepts to build those features. 24
Finally the cool thing is that the project will be more or less an implementation of the custardy itself 25
. 26
So the nice thing about this whole process is that we have to study all the features. 27
Then we learn all the concepts needed to implement those features and finally know what project we actually 28
implement those features. 29
This is why there is no context bitching. 30
That is we are not learning one thing and implementing something else. 31
Let me give you a shot them off the system. 32
So what you're seeing here is the home page of the system and it shows all that recently bookmarked 33
items by different users and it has three different sections and one of the sections says the articles 34
. 35
Which is basically the blinks that is there you also have pages that the users found interesting on 36
how bookmarked So it shows some of the ramblings here. 37
I Nitro's a site from which it has been downloaded so it is basically like any bookmarking website where 38
you can bookmark web links you might have used Web sites like delicious or Dick sort or similar but 39
those Web sites but it's not just the web links so it does more you or does more than these different 40
Web sites into you. 41
You can also bookmark movies and also books which are shown here. 42
So these are the two different verticals that the system provides. 43
You can bookmark items from these articles and in future we are also going to add restaurants doctors 44
businesses and even something like recipes. 45
So there are many other work because that can be included and like music. 46
And we've all been including them so that's the homepage on me just start in using my Facebook account 47
. 48
I know I'm signed in and here it shows the articles the menu shows the articles books and movies. 49
Let me just click on articles and here are all the bookmarks web that are how bookmarked. 50
And here there are two sections of read and clues. 51
So read ha ha 1176 on the wall 100 ramblings that are how much I can and you a higher on one hundred 52
and fifty seven. 53
And here is one of the ramblings and it can also have this little lock. 54
It means that it is a pirate which means that other users can never see this particular item on each 55
wabbling can also be archived. 56
So we have some of these facts. 57
That is the categories. 58
So if I click on notations so I have all the articles related to and or visions. 59
Similarly how books here and how movies. 60
So here I have Roger on two hundred and six movies and I have another 71 under list. 61
It's what we have here and we can also read them. 62
There are three ratings within the system. 63
We just call does like that. 64
Loved it. 65
And the best. 66
So like that at least one and loved it as means that other user likes it more. 67
It's a rating a ball like it and the best is like you know like a five star rating. 68
So if I click on loved it here you know. 69
So this particular item it got retired has loved it. 70
So it just says loud but are wired non-fact on the best is taught in budo why it was the best. 71
Now I can also Faktor these items by these ratings so if I click on the best it shows only the movies 72
which I feel are the best. 73
So these were rated as the best by me. 74
So these are the movies and you how are we how books also. 75
So this is my research right. 76
These are the things this is like my gold mine. 77
So these are the these are the things that I think that that interests me and I can always share it 78
with my followers also so that they benefit from it from my research. 79
And so that's the different monster that we can bookmark and within books you know let me add a bookmark 80
. 81
So we have indexed around 200000 most popular books from the web. 82
So all these books in fact that database as my school database and all these books are also inside my 83
school. 84
However if I search for a book then my Asgill is not very efficient. 85
So what we did was we indexed all of those books separately using the so large search library. 86
So so our search library is specifically banned for searching for text items. 87
So all that 200000 books have been extracted indexed separately by Saillard so large is an Apache library 88
and it builds something called as an inverted index which is a specialized data structure that allows 89
afast text searching. 90
So when I search anything it's going to head the solar index itself. 91
So let's just type in the book. 92
But often they have to search. 93
And here are a list. 94
So this is coming from the search index. 95
But let's say if the book was not on here then I can actually click here on this link and it would actually 96
make a call to a third party system API which is from Greece which is also a very popular website. 97
Hon sure. 98
All the items that are fetched from that website and I can also add the book if I can find it there 99
. 100
And so let me just click on see here. 101
So it's already saved into my account if I click here and say Here I can see that it is under red and 102
I can also move it to reduce. 103
That's it. 104
Now it's under close. 105
So that's how we read a book and movies are also ordered in the cemetery. 106
Now coming to articles we can you know we can click on this plus I can paste you are directly here. 107
I understand that the user interface is not really sleek. 108
I'm really working on it. 109
Megan said the whether it is plywood or not fly by default it gets added under the red section. 110
But if I want to add at least I can do it here and I can also give the rating and attach some tag that 111
is Katic I can categorize the book and I should just save it. 112
So that's one way of adding web links but there is a nicer way to add web links if you if and if we 113
go into the home page. 114
So there is this Tinkler's install or bookmarklet and there is a link here. 115
All we need to do is just click on this and drag it on to the browser and the button gets added. 116
So you can see a button here called through lit and that's basically the bookmarklet. 117
And how can it be helpful. 118
Let's just see. 119
So let's go to CNN.com and click on this link. 120
How did Greece get into this mess. 121
It's interesting. 122
So this is the link now that say I'm finding this interesting. 123
I want to market. 124
I just click on this link Roulette. 125
And there you go. 126
It got added into my account so if I go back into my trilogy on if I click on articles it's right here 127
that's it. 128
That's how you add web links and movies and books already and through a database. 129
So they are. 130
I did that bookmark from within the system itself that has web links. 131
They have to come from the back on soon we will be adding more articles. 132
So the goal is that really will allow us to bookmark anything. 133
So all your finds will be in one single place. 134
So that's the nice thing about it. 135
I know you can share all those winds with you or with your network with your followers and the cool 136
feature that will be our thing very soon as a personalized recommendation engine. 137
So based on what you how I did the system will automatically recommend you know stuff. 138
So which would be more interesting to you. 139
So to is something like what Amazon Dot Com does. 140
Amazon also recommends your books based on what you have purchased in the past. 141
So it's something like that and that's a shot them off to Leo