Recent posts

Flyway Self Healing

less than 1 minute read

how to let your flyway database scheme migrate more robustly and self healing

Flyway Self Healing

less than 1 minute read

how to let your flyway database scheme migrate more robustly and self healing

Az Cli

less than 1 minute read

To run commands in VMs in Azure

Cheap and flexible computing

1 minute read

whether it seems possible or not - go for it Cheaper X 2 to EC2, to use Fargate Spot With Fargate Spot you can run interruption tolerant Amazon ECS t...

Understanding React export a Component

1 minute read

A young idler, an old beggar. - William Shakespeare Understanding React export a Component In this blog post, we will dive into the code of the RepoU...

UUID deep dive

4 minute read

A young idler, an old beggar. - William Shakespeare

which-port-my-service-is-running

2 minute read

Summary As a Java developer, it’s important to know how to find out which port number your Spring service is running on. This information is useful when you ...

Elk Search Tips

less than 1 minute read

message:/'Invoking SP with quoteContext*werqewr-1234asdf-sdf23-9d83-asdf23*'/

what is StrictHostKeyChecking in ssh

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What’s and how to avoid error of the authenticity of host ‘xxx’ can’t be established You can suppress the “The authenticity of host ‘’ can’t be established” ...

Chinese Verb

less than 1 minute read

知其雄,守其雌 什么意思

What’s Difference Of Cny And Cnh

3 minute read

what’s difference of CNY and CNH CNY and CNH are both currencies used in China, but they are different in a few important ways:

Spring Cloud Master Piece 9

7 minute read

What’s spring cloud config Spring Cloud Config is a distributed configuration server that provides a centralized location to manage external properties for a...

Spring Cloud Master Piece 6

1 minute read

Sample me build a micro service payment system with spring cloud Here’s an example of building a microservice payment system using Spring Cloud:

Spring Cloud Master Piece 2

5 minute read

what’s usage of bootstrap yml In a Spring Boot application, the bootstrap.yml (or bootstrap.properties) file is used for configuring the application’s enviro...

Spring Cloud Master Piece 1

7 minute read

what’s API gateway An API Gateway is a key component in microservices architecture that acts as a single entry point for client requests to a microservices-b...

Master Microfrontends

4 minute read

“The only way to do great work is to love what you do.” - Steve Jobs

How To Config JFR Java Flight Control

2 minute read

“Climb the mountains and get their good tidings. Nature’s peace will flow into you as sunshine flows into trees. The winds will blow their own freshness i...

Google マップ内の写真のコメントが表示されない

less than 1 minute read

紹介 私は、私のOppo Androidスマートフォンのアプリ「Googleマップ」で奇妙な問題が発生していることに気づきました。Googleマップで特定の場所(例えば「中央公園」)を検索すると、通常、このアプリは公園の写真やコメントリストを表示するはずです。例えば、誰かが公園の芝生や川の写真を投稿し、便利な場所...

master-cglib-in-java

2 minute read

You are not a drop in the ocean, you are the entire ocean in a drop.

Minium Workable Mvp Vimrc

6 minute read

”—————————————————————- “ 4. User interface “—————————————————————- “ Set X lines to the cursor when moving vertically set scrolloff=0

Linux Tips

8 minute read

Remember, some things have to end for better things to begin.

How to user fire extinguisher

less than 1 minute read

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 Kubernetes Client API

1 minute read

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...

Whitelabel Error Page

less than 1 minute read

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...

Debts in a nutshell

less than 1 minute read

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...

How to process data from S3 download URL

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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

1 minute read

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

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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...

JVM热身

1 minute read

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/

Mock in kotlin

2 minute read

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

2 minute read

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

1 minute read

Dockers Concepts

Curl

less than 1 minute read

Linux Curl command

AOP

less than 1 minute read

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

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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...

Awesome SSL certificates and HTTPS

16 minute read

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

13 minute read

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

54 minute read

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...

Conversations with God

less than 1 minute read

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

4 minute read

Enable Kafka listener annotated endpoints that are created under the covers by a AbstractListenerContainerFactory. To be used on Configuration classes as fol...

Mifid

1 minute read

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

less than 1 minute read

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...

Seconds

less than 1 minute read

nano seconds

Citrix receiver

less than 1 minute read

“Cannot connect to remote desktop” with Citrix Receiver

Guice

7 minute read

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

less than 1 minute read

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...

Mockito

less than 1 minute read

Feature

Protobuf

5 minute read

What are protocol buffers?

Sudo in a Nutshell

6 minute read

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

14 minute read

ZK Motto the motto “ZooKeeper: Because Coordinating Distributed Systems is a Zoo.”

Cucumber

28 minute read

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

less than 1 minute read

Scala String

akka framework of scala

27 minute read

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...

Apache Camel

8 minute read

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 ...

JXM

less than 1 minute read

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

1 minute read

Solace PubSub+ It is a message broker that lets you establish event-driven interactions between applications and microservices across hybrid cloud environmen...

Apigee

4 minute read

App deployment, configuration management and orchestration - all from one system. Ansible is powerful IT automation that you can learn quickly.

Ansible

10 minute read

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

4 minute read

How Flexbox works — explained with big, colorful, animated gifs

KDB

18 minute read

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...

Portactor

1 minute read

Better to use smart wait

Agile and SCRUM

less than 1 minute read

Key concept In Scrum, a team is cross functional, meaning everyone is needed to take a feature from idea to implementation.

rxjs pipe in depth

6 minute read

https://stormforger.com/blog/2016/07/08/types-of-performance-testing/

Strategy-Of-Openshift-Releases

less than 1 minute read

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

less than 1 minute read

commands to read files var lineReader = require(‘readline’).createInterface({ input: require(‘fs’).createReadStream(‘C:\dev\node\input\git_reset_files.tx...

Minium Viable Product

less than 1 minute read

https://blog.leanstack.com/minimum-viable-product-mvp-7e280b0b9418

CORS :Cross-Origin Resource Sharing

1 minute read

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

2 minute read

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

3 minute read

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,...

cloud computering

less than 1 minute read

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

3 minute read

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

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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

less than 1 minute read

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...

Container

2 minute read

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

less than 1 minute read

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 ...

JDK source

less than 1 minute read

interface RandomAccess Marker interface used by List implementations to indicate that they support fast (generally constant time) random access. The primary ...

SSH SFTP

4 minute read

Secure FTP SFTP over FTP is the equivalant of HTTPS over HTTP, the security version

AWS Tips

less than 1 minute read

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

less than 1 minute read

ORA-12899: Value Too Large for Column

Spring notes

27 minute read

Spring Bean Life Cycle Callback Methods

Kindle notes

113 minute read

#《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 Security Notes

7 minute read

Java Security well-behaved: programs should be prevent from consuming too much system resources

R Language

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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

35 minute read

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

less than 1 minute read

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

less than 1 minute read

Class loading subsystem

Maven-Notes

27 minute read

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

less than 1 minute read

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...

IT-Architect

1 minute read

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

15 minute read

This page is about key points about Algorithm

Java-Tricky-Tech-Questions.md

19 minute read

What is the difference between Serializable and Externalizable in Java? In earlier version of Java, reflection was very slow, and so serializaing large ob...

Compare-In-Java

6 minute read

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

3 minute read

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

4 minute read

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

66 minute read

This blog is listing key new features introduced in Java 8

Java GC notes

28 minute read

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

12 minute read

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...

Angulary Misc

2 minute read

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

less than 1 minute read

ThreadLocalRandom, SecureRandm, java.util.Random, java.math.Random

Java new features

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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...

Simpler chronicle of CI(Continuous Integration) “乱弹系列”之持续集成工具

less than 1 minute read

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...

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。

less than 1 minute read

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

less than 1 minute read

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

less than 1 minute read

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。

http methods

11 minute read

RFC origion http://www.w3.org/Protocols/rfc2616/rfc2616-sec9.html#sec9.1.2)

Spark-vs-Storm

less than 1 minute read

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

less than 1 minute read

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。

kibana, view layer of elasticsearch

less than 1 minute read

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

less than 1 minute read

What’s Kibana kibana is an open source data visualization plugin for Elasticsearch. It provides visualization capabilities on top of the content indexed on...

iConnect

less than 1 minute read

UI HTML5, AngularJS, BootStrap, REST API, JSON Backend Hadoop core (HDFS), Hive, HBase, MapReduce, Oozie, Pig, Solr

Business Analysis

less than 1 minute read

Purpose of BA 带来一些商业价值(收益) 解决业务痛点

Data Structure

2 minute read

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...

equity trading

less than 1 minute read

Difference between mutal funds and hedge funds

SQL

less than 1 minute read

Differences between not in, not exists , and left join with null

HTTPS/2

less than 1 minute read

concepts

Github page commands notes

less than 1 minute read

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

1 minute read

RQFII RQFII stands for Renminbi Qualified Foreign Institutional Investor. RQFII was introduced in 2011 to allow qualified foreign institutional investors to ...

Load Balancing

less than 1 minute read

Concepts LVS means Linux Virtual Server, which is one Linux built-in component.

Python

less than 1 minute read

(‘—–Unexpected error:’, <type ‘exceptions.TypeError’>) datetime.datetime.now()

Setup Git in Mint Linux

less than 1 minute read

How to setup Git in Mint Linux =================================================

Microservices vs. SOA

1 minute read

Microservice Services are organized around capabilities, e.g., user interface front-end, recommendation, logistics, billing, etc. Services are small in ...

Java Class Loader

33 minute read

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...