kottans-backend: A JavaScript repository from OperKH

Git Intro

name (at least) one thing that was new to you:

Working with git in console
Staging Index
git show

name (at least) one thing that surprised you:

git config --global core.editor "code --wait"

name (at least) one thing you intend to use in the future:

git log --oneline
git log --stat
git log --oneline --all --graph

Udacity: Version Control with Git

Working with git in console is powerful. I liked git log --oneline --all --graph and git log --stat commands, but resolving conflicts in GUI much more convenient for me.

Unix Shell

name (at least) one thing that was new to you:

lpr
lpq
lprm

name (at least) one thing that surprised you:

finger is not default(pre installed) package in Debian

name (at least) one thing you intend to use in the future (also used them before):

cp
more
grep

Linux Survival

Git Collaboration

name (at least) one thing that was new to you:

git shortlog
git log --author=""

name (at least) one thing that surprised you:

git log --grep=""

name (at least) one thing you intend to use in the future:

git log --grep=""

Udacity: GitHub & Collaboration

NodeJS Basics 1

name (at least) one thing that was new to you:

trampoline function implementation
The last task of "functional javascript workshop"
Work with crypto, tar and zlib in NodeJS

name (at least) one thing that surprised you:

The last task of "functional javascript workshop" surprised of using call on Function.prototype and I found a new way of IIFE implementation.

name (at least) one thing you intend to use in the future:

I think crypto module

Courses

Memory Management

What's going to happen if program reaches maximum limit of stack ?

We will get a stack overflow and the program will receive a Segmentation Fault.

What's going to happen if program requests a big (more then 128KB) memory allocation on heap ?

Anonymous memory mapping will be created (it will be created in MMS, not in heap) this allocation will not correspond to any files and program can use it instead of heap.

What's the difference between Text and Data memory segments ?

Text Segment maps the part of the program's binary image that contains program code and string literals. This segment is read only writes to this area earn program a Segmentation Fault.
Data Segment maps the part of the program's binary image that contains the initial static values given in source code. This segment is a private memory mapping, which means that updates to memory are not reflected to binary file and program able to change variable values w/o errors.

$ cat /proc/self/maps
7f06fe260000-7f06fe3f5000 r-xp 00000000 00:00 273595             /lib/x86_64-linux-gnu/libc-2.24.so
7f06fe3f5000-7f06fe3fd000 ---p 00195000 00:00 273595             /lib/x86_64-linux-gnu/libc-2.24.so
7f06fe3fd000-7f06fe5f5000 ---p 0000019d 00:00 273595             /lib/x86_64-linux-gnu/libc-2.24.so
7f06fe5f5000-7f06fe5f9000 r--p 00195000 00:00 273595             /lib/x86_64-linux-gnu/libc-2.24.so
7f06fe5f9000-7f06fe5fb000 rw-p 00199000 00:00 273595             /lib/x86_64-linux-gnu/libc-2.24.so
7f06fe5fb000-7f06fe5ff000 rw-p 00000000 00:00 0
7f06fe600000-7f06fe622000 r-xp 00000000 00:00 273573             /lib/x86_64-linux-gnu/ld-2.24.so
7f06fe622000-7f06fe623000 r-xp 00022000 00:00 273573             /lib/x86_64-linux-gnu/ld-2.24.so
7f06fe688000-7f06fe823000 r--p 00000000 00:00 274226             /usr/lib/locale/locale-archive
7f06fe823000-7f06fe824000 r--p 00023000 00:00 273573             /lib/x86_64-linux-gnu/ld-2.24.so
7f06fe824000-7f06fe825000 rw-p 00024000 00:00 273573             /lib/x86_64-linux-gnu/ld-2.24.so
7f06fe825000-7f06fe826000 rw-p 00000000 00:00 0
7f06fe8a0000-7f06fe8c2000 rw-p 00000000 00:00 0
7f06fe8d0000-7f06fe8d2000 rw-p 00000000 00:00 0
7f06fe8e0000-7f06fe8e3000 rw-p 00000000 00:00 0
7f06fea00000-7f06fea07000 r-xp 00000000 00:00 8510               /bin/cat
7f06fea07000-7f06fea08000 r-xp 00007000 00:00 8510               /bin/cat
7f06fec07000-7f06fec08000 r--p 00007000 00:00 8510               /bin/cat
7f06fec08000-7f06fec09000 rw-p 00008000 00:00 8510               /bin/cat
7fffde65d000-7fffde67e000 rw-p 00000000 00:00 0                  [heap]
7fffe5f12000-7fffe6712000 rw-p 00000000 00:00 0                  [stack]
7fffe69da000-7fffe69db000 r-xp 00000000 00:00 0                  [vdso]

Segment	Address fragments
Heap	7fffde65d000-7fffde67e000
Stack	7fffe5f12000-7fffe6712000
MMS	7f06fe260000-7f06fe3f5000

name (at least) one thing that was new to you:

That libs are mapped to MMS
That Heap grows up and Stack grows down
Text, Data and BBS segments - very interesting part read more than 5 times :)
Segments offset randomization

name (at least) one thing that surprised you:

Stack grows down

name (at least) one thing you intend to use in the future:

Memory Profiles in Chrome

TCP. UDP. Network

name (at least) one thing that was new to you:

mtr, host, dig, nc

name (at least) one thing that surprised you:

how traceroute manipulates with TTL value to trace packets path

name (at least) one thing you intend to use in the future:

host and dig in addition to traceroute
nc - it's convenient. In Windows I used telnet instead :)

Courses

Http & Https

Add answers to the following questions to your repository:

Name at least three possible negative consequences of not using https.

Privacy: Some sensitive info like credentials, private messages can be stolen

Integrity: No guaranty that you see info without changes

Identification: No guaranty that communication is between you and real domain (e.g. DNS Spoofing)

Explain the main idea behind public key cryptography in few sentences

Everyone can encrypt information using public key, but decrypt this info is possible only with owners private key. Owner of the private key can encrypt some info using their private key, and this info can be decrypted by everyone how has owners public key - in that way owner sign info and another person by encrypting this info by owner public key - identifies that this info 100% signed by owner.

You are creating an application for pet clinic. You need to implement the following functionality:

add new pet (including name, age, breed, owner's name, medical history)

POST /pet

Payload - body:
{
  name: string,
  age: number,
  breed: string,
  ownersName: string,
  medicalHistory: medicalHistory[]
}
Response:

OK - Status code 200 and body with created pet id

If something wrong with user payload - Status code 400 and body with validation description by each field

search pet by name

GET /pet/findByName

Payload - query:

name=Sparky

Response:

OK - Status code 200 and body with Pet object (including name, age, breed, owner's name, medical history)

Not found - Status code 404

change name of an existing pet

PATCH /pet/{petId}/name

Payload - body:
{
  name: string
}
Response:

OK - Status code 200

If Id doesn't exist or User doesn't have access to this pet (even if it exist) - Status code 404 and message "Not found" - to not allow brutforse existing or not existing ids

add new info about pet's health

POST /pet/{petId}/health

Payload - body: medicalHistory Object

Response:

OK - Status code 200. May be Id if generated by DB

If something wrong with user payload - Status code 400 and body with validation description by each field

assign a pet to a particular doctor in the clinic

PUT /pet/{petId}/doctor

Payload - body:
{
  doctorId: string
}
OK - Status code 200.

Doctor not exist - Status code 404.

POST /pet/{petId}/appointment

Payload - body:
{
  doctorId: string
  date: string - dateTime format ISO string
}
OK - Status code 200.

If something wrong with user payload - Status code 400 and body with validation description by each field

OperKH/kottans-backend

Git Intro

Unix Shell

Git Collaboration

NodeJS Basics 1

Memory Management

TCP. UDP. Network

Http & Https