CS = CurioSity

Question 1

What is the meaning of canary ? Is canary necessary for a rollout deployment ?

Answer 1

Will there really be downtime if the canary service is not deployed and n>1 pods are running ?

Historical:
Because canaries were once used in coal mining to alert miners when toxic gases reached dangerous levels. Like the canary in a coal mind, the end user who is selected to receive new code in a canary test is unaware he is being used to provide an early warning.

Question 2

what does the sed command line mean?

Answer 2

Stream EDitor

Question 3

pub/sub ?

Answer 3

publisher / suscriber

Question 4

Pub/Sub topic ?

Answer 4

A named resource to which messages are sent by publishers.

Question 5

autospec (in patch)

Answer 5

more restrictive when patch( … , autospec=True)

eg. same signature function, output of the same type ect…

Question 6

ETL ?

Answer 6

Extract Transform Load

ETL is short for extract, transform, load, three database functions that are combined into one tool to pull data out of one database and place it into another database.

Extract is the process of reading data from a database. In this stage, the data is collected, often from multiple and different types of sources.
Transform is the process of converting the extracted data from its previous form into the form it needs to be in so that it can be placed into another database. Transformation occurs by using rules or lookup tables or by combining the data with other data.
Load is the process of writing the data into the target database

Question 7

scio

Answer 7

An API written in Scala that Spotify uses for Apache Beam and Google Cloud Dataflow.

Question 8

scalding

Answer 8

Scalding is a Scala library that makes it easy to specify Hadoop MapReduce jobs. Scalding is built on top of Cascading, a Java library that abstracts away low-level Hadoop details. Scalding is comparable to Pig, but offers tight integration with Scala, bringing advantages of Scala to your MapReduce jobs.

Question 9

REPL ?

Answer 9

Read-Eval-Print Loop

Question 10

Maven

Answer 10

Maven is a build automation tool used primarily for Java projects. Maven addresses two aspects of building software: first, it describes how software is built, and second, it describes its dependencies

Question 11

CQRS ?

Answer 11

command query responsibility segregation

<a>link</a>

Question 12

TCP

Answer 12

TCP (Transmission Control Protocol) is a connection oriented stream over an IP network. It guarantees that all sent packets will reach the destination in the correct order. This imply the use of acknowledgement packets sent back to the sender, and automatic retransmission, causing additional delays and a general less efficient transmission than UDP.

UDP is a connection-less protocol. Communication is datagram oriented. The integrity is guaranteed only on the single datagram. Datagrams reach destination and can arrive out of order or don’t arrive at all. It is more efficient than TCP because it uses non ACK. It’s generally used for real time communication, where a little percentage of packet loss rate is preferable to the overhead of a TCP connection.

In certain situations UDP is used because it allows broadcast packet transmission. This is sometimes fundamental in cases like DHCP protocol, because the client machine hasn’t still received an IP address (this is the DHCP negotiaton protocol purpose) and there won’t be any way to establish a TCP stream without the IP address itself.

Question 13

._ah ?

Answer 13

apphosting

Question 14

Java SE, EE

Answer 14

Standard Edition, Enterprise Edition

Question 15

pom.xml ?

Answer 15

A Project Object Model or POM is the fundamental unit of work in Maven

Question 16

Web Server Gateway Interface

Answer 16

WSGI is the Web Server Gateway Interface. It is a specification that describes how a web server communicates with web applications, and how web applications can be chained together to process one request.

Question 17

Difference btw Forward and Reverse proxy

Answer 17

Differences Between Forward Proxy and Reverse Proxy. The main difference between the two is that forward proxy is used by the client such as a web browser whereas reverse proxy is used by the server such as a web server. Forward proxy and the client can be in the same internal network, or it can be on the Internet.

Question 18

Prefork worker model

Answer 18

“pre”-fork”:

so that time is not wasted forking only when a worker is needed

Question 19

lsof

Answer 19

command meaning “list open files”, which is used in many Unix-like systems to report a list of all open files and the processes that opened them.