Head First Blockchina 1
深入浅出区块链系统：第一章.
what you should know about blockchain
考虑的大家现在很多都是碎片化阅读，不知道大家如何，反正如果我是在在只有很短一段时间里，不太容易切换状态静下心来读一篇洋洋洒洒的长文章。因此此系统会保持短小精悍，把整套分成一系列小文章，每个文章有分成若干个段（sections）。既KISS原则，查看这里什么是KISS.
目前区块链（blockchain）应该是在最近比较火的新技术之一了，这个不光在银行金融行业，也在其他诸多行业逐渐成为热点。区块链基于被认为是继互联网之后最重要的技术发明之一。看到过很多关于区块链的文章，要么是太过于学术，要么又局限于某个行业领域。对于一般人来说不太容易去理解其所以然。因此，笔者提笔自己写一个关于区块链的系列文章，以方便大家。
比特币
说到区块链就不得不提比特币。在进入讨论blockchain之前，先上张图片。
这个是在说雷曼兄弟公司的破产，背景是发生于2008年金融危机。当时被媒体及世人厌恶的贪婪，低效的传统金融体系垮塌，与此同时，不知道是不是巧合，比特币（bitcoin）诞生了（其实电子货币已经有几十年的历史了）。
比特币，就像是美元，人民币一样是个货币，只是这个是数字化的货币，没有一个具体的国家或者机构管理。既然是货币就要拿来用，要流通。当有任何变动，就会产生所谓的 money in money out， balance changed。即这些比特币的变动，最新的余额是多少，等都要记录下来。在现实世界中，这些记录在具体你的每个银行账户中，由一些监管机构监视并确保准确性。
但是比特币是个电子货币，没有一个具体的营业监管机构。怎么破？
这时区块链就被发明出来（大约是在2009年），区块链起源于比特币，就是当比特币从一个人转移到另一个人时，用于记录这些变动。换句话说，区块链（Blockchain） 就是比特币（bitcoin）的不可变动（immutable）的记账系统。
记账
有人可能会觉得“记账系统”太过于笼统，不太明白，因此首先这里说一下什么是记账，举个例子，你在淘宝上买东西，整个过程需要有多个记账操作，包括可能需要在购物车里添加一条记录，你买好了需要在商家那里记一笔账，然后支付时需要记下一笔，快递再需要记录一笔。如果你买的不是一般的小东西，比如是一个房子，那样还要在相关管理部门还要记录一笔。 有没有发现这个是非常低效的，需要花费很多的重复资源的过程？换句话说，这些低效都是最终都要转嫁到我们消费者头上。区块链却在设计之初很好的解决上面这些弊端。
什么是区块链
区块链是专门针对比特币设计开发的记账系统，用于所有比特币的记账。因为区块链本身良好的设计，区块链被服务于比特币仅仅只是一个用例和开端，其还可以用于很多地方。
记住这几个词可以帮助理解什么是区块链
- chain/链。 像下面这个图，数据的组织是由一个一个
大小相同的块(block)组成一个链条(chain)，就像是DNA里每个基因有机的组织在一起。
.
下面使用一个例子来解释一下。当有如下三个操作时就会在区块链中添加三条记录。
-
去中心化，或者说是“分布式” ， 也就是具体的这些记账数据是分布式的散落在各个节点，而且每个节点都存有一份
所有的交易。这样有个好处，就是每个交易有多份副本，互相之间可以对比查对，那些欺诈，篡改数据就没有可能了。其实，传统金融业有一个问题就是各个金融机构间互相的不信任，想像一下在2008年金融危机时，各个金融机构竞相抢购那些credit default derivatives等产品，就是因为大家对对方的不信任所引起的。 -
挖矿。 “矿工”，其实就是链中一个个能够保存对账信息的
节点的别名. 当有新的对账或者交易时，应该就是把数据写到某个节点，然后再需要加入到区块链中时。但问题是“链”只有一个，节点有很多，到底由哪个节点来完成这个任务呢？解决办法就是“打”，看谁厉害。其实就是许多的矿工节点会互相竞争，使用一些非常耗费计算资源，后台使用复杂的算法，最后使用一种叫做 PoW （Proof Of Work,是一种快速断定工作量的技术，比如你安排工人来给把一车箱子从仓库搬到车间，你并不需要从一开始紧盯着他去搬每一个箱子，只要看到最终的所有的箱子都已经在车间，即可证明他做完了工作，可以给相应的报酬了。这个我们在后续章节详细解释）的机制来决定最终哪个节点获胜，由它有资格来写这个区块，并加入到区块链中，同时这个获胜的节点可以得到相应财务上的奖励，即若干的比特币，这也正是不断激励人们投入更加强大计算能力的机器来挖矿的原因。这个过程被比特币平台很好的控制节奏，也就是大概每10分钟左右产生一个新的“区块”以添加到区块链路中。
可以参考https://blockchain.info/?currency=CNY， 这里是以人民币滚动显示当前所有挖矿的更新，下图是此屏幕截图。
区块链的应用领域
金融业
对于金融业来说，在进行远程转账时一直在使用的所谓“关系银行”，比如你想要通过中国工商银行给朋友在澳洲的汇丰银行的账户转账，这时在中间可能要经过在香港的汇丰以及悉尼的银行等多个第三方机构来中转，不光要多花手续费，真正拿到手时可能已经1周时间过去了。如果使用区块链，转账其实就是添加一个“对账”信息块并加入到区块链中即可，对方银行可以立即在链中发现此交易。这样此过程就流水化（streamline）了，就跟发个电子邮件似的。 相对于之前，区块链会有3个优势，（1）不需要经过第三方 （2）快 （3）省钱
一般商业公司
设想一下普通办公场景，一般业务处理都会涉及到许多纸制的表格，文件，请多文件的复印件等等。一是方便文件信息的传递，记录，另外一个原因是为了应付内部外部的审计。如果使用区块链，这些问题都得到很好的解决。比如，由于区块链的系统架构，其本身数据就是自动审计的。简言之，在这个领域，区块链有3大优势，（1）数据透明（2）数据安全性验证（3）审计。
对于零售行业
比如说你想知道这个食品是不是有机食品，而每个环节的数据都是散落在各个地方，不便于统一追踪。另外，数据的来源又是多种多样，又容易被篡改，比如作为一个钻石加工商，我是无法确定这批钻石是不是血钻。而“区块链”本身的特性保证了可以跟踪产品生命周期的每个阶段详细信息，而且区块链的“只能添加”的属性也确保了数据数据的准确性，不容易被后期篡改。因此区块链也可以用以政府类的投票，这样就更加具有合法性，不可能被人为篡改结果。
小结
以上的案例都涉及到一个关键词 “信任”。 你不信任供应链路，你不信任 “相关银行”， 等。但是你可以信任 “区块链”，它是允许多个不同的机构一起协同工作，但是不需要他们之间相互信任。
FAQ （常问的问题）
这些 “区块” 具体是什么样子的？
首先每个区块包含有一个时间戳，包含一个哈希码，指向其前面链接的区块，然后就是对账交易数据本身。每个区块都有一个唯一编号，生成这个编号是需要大量的计算工作及验证。我们在后续章节详细介绍此功能。
什么样新的块才能够加入
当需要添加新的块时，需要有所有节点中50%认为正确同意才可以。这样可以保证恶意的数据被加入到链中。
每个节点都存一份不也是有额外的成本吗
其实在2010年，1P (Peta byte)数据存储一个月是 $80,000/month,预计在2020年，也就是10年后，同样的1P的数据存储一个月只要 $4/month. 可见，存储本身的成本几乎可以越来越忽略不计了。
总之，BlockChain的出现，是由于人们的预期， 技术的进步。
所有上面提到的东西，包括此文章的markdown源代码，mindmap思维导图等等都可以在我的github上找到。此文章是我在GitBook上此系统的第一篇，链接。如果有任何建议或者想法，请联系我。
联系我：
- phray.zhang@gmail.com (email/邮件，whatsapp, linkedin)
- helloworld_2000 (wechat/微信)
- github
- [简书 jianshu]（http://www.jianshu.com/users/a9e7b971aafc）
- 微信公众号：vibex
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”—————————————————————- “ 4. User interface “—————————————————————- “ Set X lines to the cursor when moving vertically set scrolloff=0
How to build unit/integration tests for Spring State Machine
Get busy living or get busy dying.
Magic after maven target spring-boot-run
Turn your wounds into wisdom
Bamboo pipeline deployment failure caused by Kubenetes Finalizer
Today a reader, tomorrow a leader.
Error in WSL in windows, command not found: sdk
Never stop learning, because life never stops teaching.
Could not write JSON: Value out of range. Value: “xxxxx” Radix:10
Life is really simple, but men insist on making it complicated.
Gemfire Geode Error on Peer or client version with ordinal xx not supported. Highest known version is 1.12.1 Client
Take the risk or lose the chance!
Password must not null in gemfire and geode, but I’ve assigned password in yaml properties file
Worries less, smile more!
One page to cover most commonly found errors for fat jar in SpringBoot
Kill time, or kiss time!
Awesome Shortcuts to boost productivity
One must learn by doing the thing; for though you think you know it, you have no certainty, until you try. —Sophocles
Core Java tips required an interview
Success is the sum of small efforts, repeated.
Tell me difference of truststore and keystore in short answer
Do what you say, say what you do.
GIT useful scripts or error solutions
Don’t wish for it, work for it.
Tell me difference of yarn install and npm install in short answer
Don’t find fault. Find a remedy.
Bible blog for most commonly found Gradle errors
People are smarter than you think. Give them a chance to prove themselves.
Pearls in Front end development
Be happy in front of people who don’t like you, it kills them.
Ruby from zero to hero
This is your life. Do what you love, and do it often.
Everything you’d know for Groovy interviews
Life is short. Don’t waste it with negative people who don’t appreciate you. Keep them in your heart but keep them out of your life.
To outstanding as professional MacBook pro user
The most effective way to do it, is to do it Homebrew The best practice is to run brew info before install new software. It will generally list what’s c...
Failed to install gem in Mac, incompatible architecture and missing psych
Burn your ego before it burns you.
IntelliJ Tips to boost your productivity 10 times
Don’t be afraid to make s splash.
Everything you’d know about state machine for interviews
Less expecting, more accepting.
Tips about algorithm resolving from Leetcode
Stay focused, believe that you can achieve at the highest level, surround yourself with others who believe in you and do not stray from your goals.
Solution center for Node errors
Fina a way. If there’s none, make one!
Triple your productivities by Visual studio code keyboard shortcuts
The sentence The quick brown fox jumps over the lazy dog uses every letter of the alphabet.
TypeScript noteworthy notes
The moment you start focusing on yourself, things start falling into place.
RXJS – reactive Programming like a hero
When love is real, it doesn’t lie, cheat, pretend or keep secrets.
Concurrency in Java
Little things make big things happens.
Linux Tips
Remember, some things have to end for better things to begin.
A taste of GraphQL
A good day starts with a good mindset!
A taste of GraphQL
A good day starts with a good mindset!
What’s inside magic in Spring Data JPA
A good day starts with a good mindset!
What’s inside magic in Spring Data JPA
A good day starts with a good mindset!
Why Spring turn a column name from camelNaming to snake_Naming
Don’t spend another year doing the same shit.
Some mistakes you’d avoid in java
With great power comes great responsibilities.
Untold stories for Jupiter, any differences JUnit 5 vs Junit 4
Don’t tell people your plans. Just show them your results!
Git commands you can show off for 100 years
Life is short, make a big splash!
FileNotFound Exception when loading data file in IntelliJ
Take time to do what makes your soul happy!
How to ace AWS certification just like play a game
Life isn’t about finding yourself. Life is about creating yourself.
Java Deep Notes
Java Deep Notes
Code to draw a Big H with all stars
Coding is everything! Code Now!
Code to draw a Big H with all stars
Coding is everything! Code Now!
Single vs Double precisions, float vs double data type
Leave nothing for tomorrow which can be done today. -Abraham Lincoln.
SkipTest-Not-Work-In-Multiple-models-project
Leave nothing for tomorrow which can be done today. -Abraham Lincoln.
SkipTest-Not-Work-In-Multiple-models-project
Leave nothing for tomorrow which can be done today. -Abraham Lincoln.
Maven error and solution on No such host is known
Don’t promis when you are hapy. Don’t reply when you’re angry and don’t decide when you’re sad Service keep on restarting If you spot service is restartin...
Maven error and solution on No such host is known
Don’t promis when you are hapy. Don’t reply when you’re angry and don’t decide when you’re sad
Gradle build stuck
Gradle build stuck, keep on running but never ending
2021
Save my eyes, let your cell phone to read screen content to you
Too much screen time
How logging system Bootstrapped in Spring Boot Application
Summary Following diagram demonstrated the process to bootstrap and use Logback for loggings in Spring Boot applciation.
SQLServer Error about This driver is not configured for integrated authentication
Symptoms When you are using integrated authentication (Kerberos connection) for MS SqlServer connection, there is one possible error :
How to copy files from resources folder in jar and save to a file
Why to extract resources from jar to local disk
Debug of SpringBoot run not working in IntelliJ
Normal approach to debug maven
How to watch specific kubenetes deployment by labels
How to watch specific kubenetes deployment by labels
Failed to talk to github.com from corporation network
Background It’s typical to get various network connection issues when you run commands within corporation network. For example, you’ll find diversed issues w...
Day-Day-Up-Java
More developer friendly Threa Sleep
How to user fire extinguisher
Summary As you know, staff and your safety is paramount. So what if emergency take place, such as fire in office, how to help yourself and your colleagues by...
Deep dive into ApplicationEvent in SpringBoot
Summary As you know, there are various event will be sent (multicast) when a specific story taken place.
2021-09-22-IT-Solutions-For-Remote-Learning
IT-Solutions-For-Remote-Learning.md
Deep dive into Kubernetes Client API
Summary To talk to K8s for getting data, there are few approaches. While K8s’ official Java library is the most widely used one. This blog will look into thi...
How to get CPU name, core, 64bit and speed in command line
Summary In windows operating system, if you want to get your CPU name, core, 64bit and speed in command line. Just follow below actions:
JetBrains/IntelliJ tips
Be a good person in real life, not in social media
Whitelabel Error Page
Summary Whitelabel Error Page is the default error page in Spring Boot web app. It provide a more user-friently error page whenever there are any issues when...
Google maps no photos reviews
Summary
谷歌地图里面照片的评论显示不出来
If you’d like to view solution in YouTube, check out at https://youtu.be/ICiwuqJ-yU8
Shall I still need booster even after I got dose 3?
The greatest wealth is health!
Debts in a nutshell
A debt security represents a debt owed by the issuer to an investor. Here, the investor acts as a lender to the issuer which may be a government, organisatio...
2020
How to process data from S3 download URL
S3 download URL As you know, AWS S3 object can be downloaded/processed by S3 download URL. I’m showing you two examples on how to process S3 Object by NIO f...
Debug Stuck IntelliJ
What happened to a debug job hanging in IntelliJ (IDEAS) IDE? You may find when you try to debug a class in Intellij but it stuck there and never proceed, e....
Awesome Kotlin
Difference with Scala Kotlin takes the best of Java and Scala, the response times are similar as working with Java natively, which is a considerable advantag...
Awesome tips for Chrome
Shortcuts & tips
JVM热身
此文是作者英文原文的翻译文章，英文原文在：http://todzhang.com/posts/2018-06-10-jvm-warm-up/
Awesome tips and shortcuts for Slack
Shortcuts for Slack
Awesome Reactive programming
Key points of Reactive Programming
Awesome Swift for iOS
Frame in Swift
Mock in kotlin
Argument Matching & Answers For example, you have mocked DOC with call(arg: Int): Intfunction. You want to return 1 if argument is greater than 5 and -1 ...
Mock in kotlin
Argument Matching & Answers For example, you have mocked DOC with call(arg: Int): Intfunction. You want to return 1 if argument is greater than 5 and -1 ...
Docker
Dockers Concepts
How to decode path parameters in All REST WebServices calls
How to decode path parameters in All REST WebServices calls
Curl
Linux Curl command
AOP
The concept of join points as matched by pointcut expressions is central to AOP, and Spring uses the AspectJ pointcut expression language by default.
Micrometer notes
As a general rule it should be possible to use the name as a pivot. Dimensions allow a particular named metric to be sliced to drill down and reason about th...
Pigeons in holes principle
# Pigeonhole principle
Awesome solutions for algorithm questions
你就会发现只要涉及递归的问题，都是 树的问题。
A Facial Recognition utility in a dozen of LOC
A Facial Recognition utility in a dozen of python LOC (Lines Of Code)
Awesome SSL certificates and HTTPS
What’s TLS TLS (Transport Layer Security) and its predecessor, SSL (Secure Sockets Layer), are security protocols designed to secure the communication betwee...
JVM warm up by Escape Analysis
Why JVM need warm up I don’t know how and why you get to this blog. But I know the key words in your mind are “warm” for JVM. As the name “warm up” suggested...
Java Concurrent Column 2
This is the second half about Java Concurrent of my blog
Java Concurrent
This blog is about noteworthy pivot points about Java Concurrent Framework Back to Java old days there were wait()/notify() which is error prone, while fr...
Algorithm notes from Leecode – 1
Algorithm Leetcode
2019
Conversations with God
Feelings is the language of the soul. If you want to know what’s true for you about something, look to how your’re feeling about.
Kafka In Spring
Enable Kafka listener annotated endpoints that are created under the covers by a AbstractListenerContainerFactory. To be used on Configuration classes as fol...
Terraform
Why Terraform
Kafka
Kafka
Mifid
FX Spot is not covered by the regulation, as it is not considered to be a financial instrument by ESMA, the European Union (EU) regulator. As FX is considere...
Foreign Exchange
currency pairs Direct ccy: means USD is part of currency pair Cross ccy: means ccy wihtout USD, so except NDF, the deal will be split to legs, both with...
2018
Seconds
nano seconds
Citrix receiver
Simple Binary Encoding (SBE)
Citrix receiver
“Cannot connect to remote desktop” with Citrix Receiver
Guice
A new type of Juice Put simply, Guice alleviates the need for factories and the use of new in your Java code. Think of Guice’s @Inject as the new new. You wi...
YAML
Key points All YAML files (regardless of their association with Ansible or not) can optionally begin with — and end with …. This is part of the YAML format a...
Distruptor
multithreading
Mockito
Feature
Protobuf
What are protocol buffers?
Sudo in a Nutshell
Sudo in a Nutshell Sudo (su “do”) allows a system administrator to give certain users (or groups of users) the ability to run some (or all) commands as root...
Zoo-keeper
ZK Motto the motto “ZooKeeper: Because Coordinating Distributed Systems is a Zoo.”
Presto DB
WHAT IS PRESTO?
Chronicle
Overview
Cucumber
Acceptance testing vs unit test It’s sometimes said that unit tests ensure you build the thing right, whereas acceptance tests ensure you build the right thi...
Scala
Scala String
akka framework of scala
philosophy The actor model adopts the philosophy that everything is an actor. This is similar to the everything is an object philosophy used by some object-o...
File Util in Apache Camel
FileUtil.class
Apache Camel
Camel’s message model In Camel, there are two abstractions for modeling messages, both of which we’ll cover in this section. org.apache.camel.Message—The ...
QuickFixJ
Settings
JXM
Exporting your beans to JMX The core class in Spring’s JMX framework is the MBeanExporter. This class is responsible for taking your Spring beans and registe...
Solace MQ
Solace PubSub+ It is a message broker that lets you establish event-driven interactions between applications and microservices across hybrid cloud environmen...
Apigee
App deployment, configuration management and orchestration - all from one system. Ansible is powerful IT automation that you can learn quickly.
Ansible
Ansible: What Is It Good For? Ansible is often described as a configuration management tool, and is typically mentioned in the same breath as Chef, Puppet, a...
flexbox
How Flexbox works — explained with big, colorful, animated gifs
Jboss tips
commands:
Locking and multithreading
Single Writer principle
KDB
KDB However kdb+ evaluates expressions right-to-left. There are no precedence rules. The reason commonly given for this behaviour is that it is a much simple...
Foreign Exchange
Foreign Exchange markets
Portactor
Better to use smart wait
Agile and SCRUM
Key concept In Scrum, a team is cross functional, meaning everyone is needed to take a feature from idea to implementation.
DevOps-Philosophy
:100:DevOps Model Defined
rxjs pipe in depth
https://stormforger.com/blog/2016/07/08/types-of-performance-testing/
How to setup nodejs to install package from intranet
Error of ‘ECONNRESET’ You may face error ECONNRESET from intranet, even appropriate proxy tools (e.g. cntlm) is running. The errors may looks like ```bash $ ...
Strategy-Of-Openshift-Releases
Release & Testing Strategy There are various methods for safely releasing changes to Production. Each team must select what is appropriate for their own ...
NodeJs Notes
commands to read files var lineReader = require(‘readline’).createInterface({ input: require(‘fs’).createReadStream(‘C:\dev\node\input\git_reset_files.tx...
Minium Viable Product
https://blog.leanstack.com/minimum-viable-product-mvp-7e280b0b9418
What is difference between declarations, providers and import in NgModule
What is difference between declarations, providers and import in NgModule
CORS :Cross-Origin Resource Sharing
Cross-Origin Request Sharing - CORS (A.K.A. Cross-Domain AJAX request) is an issue that most web developers might encounter, according to Same-Origin-Policy,...
ngrx
Why @Effects? In a simple ngrx/store project without ngrx/effects there is really no good place to put your async calls. Suppose a user clicks on a button or...
iOS programming
View A view is also a responder (UIView is a subclass of UIResponder). This means that a view is subject to user interactions, such as taps and swipes. Thus,...
2017
cloud computering
openshift vs openstack The shoft and direct answer is `OpenShift Origin can run on top of OpenStack. They are complementary projects that work well together....
cloud computering
Concepts Cloud computing is the on-demand demand delivery of compute database storage applications and other IT resources through a cloud services platform v...
Redux
whats @Effects You can almost think of your Effects as special kinds of reducer functions that are meant to be a place for you to put your async calls in suc...
reactive programing
The second advantage to a lazy subscription is that the observable doesn’t hold onto data by default. In the previous example, each event generated by the in...
common errors in NPM or node
code E503 code E503 when run npm install packages, e.g.
Container
The Docker project was responsible for popularizing container development in Linux systems. The original project defined a command and service (both named do...
promise vs observiable
The drawback of using Promises is that they’re unable to handle data sources that produce more than one value, like mouse movements or sequences of bytes in ...
Openshift tips
Commands bible
google analysis
How Page Value is calculated
JDK source
interface RandomAccess Marker interface used by List implementations to indicate that they support fast (generally constant time) random access. The primary ...
SSH SFTP
Secure FTP SFTP over FTP is the equivalant of HTTPS over HTTP, the security version
Setup WebSphere profiles and application in command line
Setup WebSphere profiles and application in command line
AWS Tips
After establishing a SSH session, you can install a default web server by executing sudo yum install httpd -y. To start the web server, type sudo service htt...
Oracle
ORA-12899: Value Too Large for Column
Spring notes
Spring Bean Life Cycle Callback Methods
Kindle notes
#《亿级流量网站架构核心技术》目录一览 TCP四层负载均衡 使用Hystrix实现隔离 基于Servlet3实现请求隔离 限流算法 令牌桶算法 漏桶算法 分布式限流 redis+lua实现 Nginx+Lua实现 使用sharding-jdbc分库分表 Disruptor+Redis...
Java JIT compiler
This is talking about Java JIT (Just-In-Time) compiler
Java Security Notes
Java Security well-behaved: programs should be prevent from consuming too much system resources
SeriableVersionUID
Noteworthy points about SeriableVersionUID in Java
R Language
s<-read.csv("C:/Users/xxx/dev/R/IRS/SHH_SCHISHG.csv") # aggregate s2<-table(s$Original.CP) s3<-as.data.frame(s2) # extract by Frequency ordered s3...
SSH and Cryptography
SFTP versus FTPS SS: Secure Shell An increasing number of our customers are looking to move away from standard FTP for transferring data, so we are ofte...
Eclipse notes
How do I remove a plug-in? Run Help > About Eclipse > Installation Details, select the software you no longer want and click Uninstall. (On Macintosh i...
Java JVM
Class loading subsystem
Maven-Notes
Maven philosophy “It is important to note that in the pom.xml file you specify the what and not the how. The pom.xml file can also serve as a documentatio...
Java New IO
Notes JDK 1.0 introduced rudimentary I/O facilities for accessing the file system (to create a directory, remove a file, or perform another task), accessi...
Network Protocols
Net Protocols
IT-Architect
SOA SOA is a set of design principles for building a suite of interoperable, flexible and reusable services based architecture. top-down and bottom-up a...
Algorithm
This page is about key points about Algorithm
Dead Lock
Concept
Java-Tricky-Tech-Questions.md
What is the difference between Serializable and Externalizable in Java? In earlier version of Java, reflection was very slow, and so serializaing large ob...
NavigableMap Misc
What is NavigableMap
Compare-In-Java
Concepts If you implement Comparable interface and override compareTo() method it must be consistent with equals() method i.e. for equal object by equals(...
Java Collections Misc
Difference between equals and deepEquals of Arrays in Java Arrays.equals() method does not compare recursively if an array contains another array on oth...
HashMap in JDK
Hashmap in JDK Some note worth points about hashmap Lookup process Step# 1: Quickly determine the bucket number in which this element may resid...
Java 8 Tips
This blog is listing key new features introduced in Java 8
Arbitrage vs Heading
What is the difference between arbitrage and hedging?
Java Enum Misc
Enum Misc
2016
Java GC notes
verbose:gc verbose:gc prints right after each gc collection and prints details about each generation memory details. Here is blog on how to read verbose gc
Hash Code Misc
contract of hashCode : Whenever it is invoked on the same object more than once during an execution of a Java application, the hashCode method must consis...
Apache Tips
Apache
Angulary Misc
Dependency Injection Angular doesn’t automatically know how you want to create instances of your services or the injector to create your service. You must co...
Random number in java
ThreadLocalRandom, SecureRandm, java.util.Random, java.math.Random
Java new features
JDK Versions JDK 1.5 in 2005 JDK 1.6 in 2006 JDK 1.7 in 2011 JDK 1.8 in 2014 Sun之前风光无限，但是在2010年1月27号被Oracle收购。 在被Oracle收购后对外承诺要回到每2年一个realse的节奏。但是20...
用10几行代码自己写个人脸识别程序
用10几行代码自己写个人脸识别程序
Eslastic Search
Eslastic Search
JSON lines
JSON lines
Python Scraphy
Python Scraphy
Simpler chronicle of CI(Continuous Integration) “乱弹系列”之持续集成工具
引言 有句话说有人的地方就有江湖，同样，有江湖的地方就有恩怨。在软件行业历史长河（虽然相对于其他行业来说，软件行业的历史实在太短了，但是确是充满了智慧的碰撞也是十分的精彩）中有一些恩怨情愁，分分合合的小故事，比如类似的有，从一套代码发展出来后面由于合同到期就分道扬镳，然后各自发展成独门产品的Sybase DB和微...
Head First Blockchina 3
Hyperledger Fabric for Mortals
【原创】深入浅出区块链系统：第二章
使用Solidity创建以太坊(Ethereum)智能合约(Smart Contract)
How to customize Sublime syntax highlights
Reference Sublime Scope Naming Syntax Guide
浅谈软件单元测试中的“断言” (assert)，从石器时代进步到黄金时代。
大家都知道，在软件测试特别是在单元测试时,必用的一个功能就是“断言”（Assert)，可能有些人觉得不就一个Assert语句，没啥花头，也有很多人用起来也是懵懵懂懂，认为只要是Assert开头的方法，拿过来就用。一个偶然的机会跟人聊到此功能，觉得还是有必要在此整理一下如何使用以及对“断言”的理解。希望可以帮助大家...
Head First Blockchina 1
深入浅出区块链系统：第一章. what you should know about blockchain
Kubernetes 与 Docker Swarm的对比
Kubernetes 和Docker Swarm 可能是使用最广泛的工具，用于在集群环境中部署容器。但是这两个工具还是有很大的差别。
漫谈开发设计中的一些‘原则’及’设计哲学’
在开发设计中有一些常用原则或者潜规则，根据笔者的经验，这里稍微总结一下最最常用的，以飨读者。
http methods
RFC origion http://www.w3.org/Protocols/rfc2616/rfc2616-sec9.html#sec9.1.2)
Spark-vs-Storm
The stark difference among Spark and Storm. Although both are claimed to process the streaming data in real time. But Spark processes it as micro-batches; wh...
微服务
可以想像一下，之前的传统应用系统，像是一个大办公室里面，有各个部门，销售部，采购部，财务部。办一件事情效率比较高。但是也有一些弊端，首先，各部门都在一个房间里。
unmodifiableList, unmodifiableSet,unmodifiableMap
What’s it Returns an unmodifiable view of the specified set. This method allows modules to provide users with “read-only” access to internal sets. Query ope...
kibana, view layer of elasticsearch
What’s Kibana kibana is an open source data visualization plugin for Elasticsearch. It provides visualization capabilities on top of the content indexed on...
kibana, view layer of elasticsearch
What’s Kibana kibana is an open source data visualization plugin for Elasticsearch. It provides visualization capabilities on top of the content indexed on...
Anatomy of ThreadLocal
Design philosophies
iConnect
UI HTML5, AngularJS, BootStrap, REST API, JSON Backend Hadoop core (HDFS), Hive, HBase, MapReduce, Oozie, Pig, Solr
Business Analysis
Purpose of BA 带来一些商业价值（收益） 解决业务痛点
Something about RESTful architect
REST API must be hypertext driver Roy’s interview
Data Structure
Binary Tree A binary tree is a tree in which no node can have more than two children. A property of a binary tree that is sometimes important is that th...
Useful bookmarks
eBooks list of various books Node.js
heavy load web application
Common solutions
tips in as400 IBM Emulator
Toggle crosshair
Mysql operator to extract JSON
“Be the change you wish to see in the world.” - Mahatma Gandhi
equity trading
Difference between mutal funds and hedge funds
SQL
Differences between not in, not exists , and left join with null
HTTPS/2
concepts
Github page commands notes
404 error for customized domain (such as godday) 404 There is not a GitHub Pages site here. Go to github master branch for gitpages site, manually add CN...
RenMinBi International
RQFII RQFII stands for Renminbi Qualified Foreign Institutional Investor. RQFII was introduced in 2011 to allow qualified foreign institutional investors to ...
JavaScript tips
includes() vs some()
Docker Errors and Fixes
Docker Errors
Load Balancing
Concepts LVS means Linux Virtual Server, which is one Linux built-in component.
Python
(‘—–Unexpected error:’, <type ‘exceptions.TypeError’>) datetime.datetime.now()
Storage Management
RAID RAID is Reductant Array Independent Disk,
CI and CD
Concepts
XA Transactions in 2PC
Description
Setup Git in Mint Linux
How to setup Git in Mint Linux =================================================
Database sharding
DB sharding in YHD
Microservices vs. SOA
Microservice Services are organized around capabilities, e.g., user interface front-end, recommendation, logistics, billing, etc. Services are small in ...
Java Class Loader
Codecache The maximum size of the code cache is set via the -XX:ReservedCodeCacheSize=N flag (where N is the default just mentioned for the particular com...