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 between a server and a client, for example, a web server and a browser. Both protocols are frequently referred to as SSL.

A TLS/SSL certificate (simply called SSL certificate) is required to enable SSL/TLS on your site and serve your website using the secure HTTPS protocol.

We offer different types of domain-validated SSL certificates signed by globally recognized certificate authorities.

CA

A Certificate Authority (CA) (or Certification Authority) is an entity that issues digital certificates.

The digital certificate certifies the ownership of a public key by the named subject of the certificate. This allows others (relying parties) to rely upon signatures or assertions made by the private key that corresponds to the public key that is certified.

Root certificate

In the SSL ecosystem, anyone can generate a signing key and sign a new certificate with that signature. However, that certificate is not considered valid unless it has been directly or indirectly signed by a trusted CA.

A trusted certificate authority is an entity that has been entitled to verify that someone is effectively who it declares to be. In order for this model to work, all the participants on the game must agree on a set of CA which they trust. All operating systems and most of web browsers ship with a set of trusted CAs.

The SSL ecosystem is based on a * model of trust relationship*, also called ** “chain of trust” **. When a device validates a certificate, it compares the certificate issuer with the list of trusted CAs. If a match is not found, the client will then check to see if the certificate of the issuing CA was issued by a trusted CA, and so on until the end of the certificate chain. The top of the chain, the root certificate, must be issued by a trusted Certificate Authority.

Tips

The root certificate is generally embedded in your connected device. In the case of web browsers, root certificates are packaged with the browser software.

To install the Intermediate SSL certificates?

The procedure to install the Intermediate SSL certificates depends on the web server and the environment where you install the certificate.

For instance, Apache requires you to bundle the intermediate SSL certificates and assign the location of the bundle to the SSLCertificateChainFile configuration. Conversely, NGINX requires you to package the intermediate SSL certificates in a single bundle with the end-user certificate.

SSL certificate chain

There are two types of certificate authorities (CAs): root CAs and intermediate CAs. In order for an SSL certificate to be trusted, that certificate must have been issued by a CA that is included in the trusted store of the device that is connecting.

In this model of trust relationships, a CA is a trusted third party that is trusted by both the subject (owner) of the certificate and the party relying upon the certificate.

In the context of a website, when we use the term digital certificate we often refer to SSL certificates. The CA is the authority responsible for issuing SSL certificates publicly trusted by web browsers.

Anyone can issue SSL certificates, but those certificates would not be trusted automatically by web browsers. Certificates such as these are called self-signed. The CA has the responsibility to validate the entity behind an SSL certificate request and, upon successful validation, the ability to issue publicly trusted SSL certificates that will be accepted by web browsers. Essentially, the browser vendors rely on CAs to validate the entity behind a web site.

How SSL work in browser

There are 3 essential elements at work in the process described above: a protocol for communications (SSL), credentials for establishing identity (the SSL certificate), and a third party that vouches for the credentials (the certificate authority).

Computers use protocols to allow different systems to work together. Web servers and web browsers rely on the Secure Sockets Layer (SSL) protocol to enable encrypted communications. The browser’s request that the server identify itself is a function of the SSL protocol.
Credentials for establishing identity are common to our everyday lives: a driver’s license, a passport, a company badge. An SSL certificate is a type of digital certificate that serves as a credential in the online world. Each SSL certificate uniquely identifies a specific domain (such as thawte.com) and a web server.
Our trust of a credential depends on our confidence in the organization that issued it. Certificate authorities have a variety of methods to verify information provided by individuals or organizations. Established certificate authorities, such as Thawte, are well known and trusted by browser vendors. Browsers extend that trust to digital certificates that are verified by the certificate authority.

PKI

You are correct that SSL uses an asymmetric key pair. One public and one private key is generated which also known as public key infrastructure (PKI). The public key is what is distributed to the world, and is used to encrypt the data. Only the private key can actually decrypt the data though.

Say we both go to walmart.com and buy stuff. Each of us get a copy of Walmart’s public key to sign our transaction with. Once the transaction is signed by Walmart’s public key, only Walmart’s private key can decrypt the transaction. If I use my copy of Walmart’s public key, it will not decrypt your transaction. Walmart must keep their private key very private and secure, else anyone who gets it can decrypt transactions to Walmart. This is why the DigiNotar breach was such a big deal

A sample of how browser get SSL certificate

If I get an SSL certificate from a well-known provider, what does that prove about my site and how?

Here’s what I know:

Assume Alice and Bob both have public and private keys
If Alice encrypts something with Bob's public key, she ensures that only Bob can decrypt it (using his private key)
If Alice encrypts something with her own private key, anyone can decrypt it (using her public key), but they will know that it was encrypted by her
Therefore, if Alice encrypts a message first with her own private key, then with Bob's public key, she will ensure that only Bob can decrypt it and that Bob will know the message is from her.

Regarding certificates, here’s what I think happens (updated):

I generate a request for a certificate. In that request, I put my public key and a bunch of information about myself.
The certificate issuer (in theory) checks me out to make sure it knows who I am: talks to me in person, sees my driver's license, retina scan, or whatever.
If they're satisfied, the certificate issuer then encrypts my request with their private key. Anyone who decrypts it with their public key knows that they vouch for the information it contains: they agree that the public key is mine and that the information stated is true about me. This encrypted endorsement is the certificate that they issue to me.
When you connect to my site via https, I send you the certificate.
Your browser already knows the issuer's public key because your browser came installed with that information.
Your browser uses the issuer's public key to decrypt what I sent you. The fact that the issuer's public key works to decrypt it proves that the issuer's private key was used to encrypt it, and therefore, that the issuer really did create this certificate.
Inside the decrypted information is my public key, which you now know has been vouched for. You use that to encrypt some data to send to me.

Your key theory: basically right, but authentication is usually done by encrypting a cryptographically secure hash of the data rather than the data itself.

A CA’s signature on an SSL certificate should indicate that the CA has done a certain amount of diligence to ensure that the credentials on the certificate match the owner. That diligence varies, but the ultimate point is that they’re saying that the certificate they signed belongs to the entity named on it.

See http://en.wikipedia.org/wiki/Digital_signature#Definition

A public key certificate is the signed combination between a public key, identifiers, and possibly other attributes. Those who sign this document effectively assert the authenticity of the binding between the public key and the identifier and these attributes, in the same way as a passport issuing authority asserts the binding between the picture and the name in a passport, as various other pieces of information (nationality, date of birth, …).

The private key is used for signing and deciphering/decrypting.
The public key is used for verifying signatures and enciphering/encrypting.

public key cryptography: A class of cryptographic techniques employing two-key ciphers. Messages encrypted with the public key can only be decrypted with the associated private key. Conversely, messages signed with the private key can be verified with the public key.

It should be pointed out, along with all the other answers, that your private key is not always just one key that is used for both decrypting and signing messages. These should be two separate keys. This would create 4 keys for each person:

Public Encryption Key - Used to encrypt data to send to me.

Private Decryption Key - Used to decrypt messages that were encrypted using my Public Encryption Key.

Private Signing Key - Used to sign messages that I send to other people.

Public Verify Key - Used to verify that a message was, in fact, signed by me.

https://en.wikipedia.org/wiki/Savvis

Savvis - Wikipedia

Savvis, formerly SVVS on Nasdaq and formerly known as Savvis Communications Corporation, and, later, Savvis Inc., is a subsidiary of CenturyLink, a company headquartered in Monroe, Louisiana.[1] The company sells managed hosting and colocation services with more than 50 data centers[2] (over 2 million square feet) in North America, Europe, and Asia, automated management and provisioning systems, and information technology consulting. Savvis has approximately 2,500 unique business and government customers.[3][4]

The file extensions .CRT and .CER are interchangeable. If your server requires that you use the .CER file extension, you can change the extension by following the steps below:

Double-click on the yourwebsite.crt file to open it into the certificate display.
Select the Details tab, then select the Copy to file button.
Hit Next on the Certificate Wizard.
Select Base-64 encoded X.509 (.CER), then Next.
Select Browse (to locate a destination) and type in the filename yourwebsite.
Hit Save. You now have the file yourwebsite.cer


File extensions for cryptographic certificates aren't really as standardized as you'd expect. Windows by default treats double-clicking a .crt file as a request to import the certificate into the Windows Root Certificate store, but treats a .cer file as a request just to view the certificate. So, they're different in that sense, at least, that Windows has some inherent different meaning for what happens when you double click each type of file.

But the way that Windows handles them when you double-click them is about the only difference between the two. Both extensions just represent that it contains a public certificate. You can rename a file or use one in place of the other in any system or configuration file that I’ve seen. And on non-Windows platforms (and even on Windows), people aren’t particularly careful about which extension they use, and treat them both interchangeably, as there’s no difference between them as long as the contents of the file are correct.

*.pem, *.crt, *.ca-bundle, *.cer, *.p7b, *.p7s files contain one or more X.509 digital certificate files that use base64 (ASCII) encoding.

.DER = The DER extension is used for binary DER encoded certificates. These files may also bear the CER or the CRT extension. Proper English usage would be “I have a DER encoded certificate” not “I have a DER certificate”.

.PEM = The PEM extension is used for different types of X.509v3 files which contain ASCII (Base64) armored data prefixed with a “—– BEGIN …” line.

.CRT = The CRT extension is used for certificates. The certificates may be encoded as binary DER or as ASCII PEM. The CER and CRT extensions are nearly synonymous. Most common among *nix systems

CER = alternate form of .crt (Microsoft Convention) You can use MS to convert .crt to .cer (.both DER encoded .cer, or base64[PEM] encoded .cer) The .cer file extension is also recognized by IE as a command to run a MS cryptoAPI command (specifically rundll32.exe cryptext.dll,CryptExtOpenCER) which displays a dialogue for importing and/or viewing certificate contents.

.KEY = The KEY extension is used both for public and private PKCS#8 keys. The keys may be encoded as binary DER or as ASCII PEM.

The only time CRT and CER can safely be interchanged is when the encoding type can be identical. (ie PEM encoded CRT = PEM encoded CER)

What is the SSL Certificate Chain?

There are two types of certificate authorities (CAs): root CAs and intermediate CAs. In order for an SSL certificate to be trusted, that certificate must have been issued by a CA that is included in the trusted store of the device that is connecting.

Good. I see you want to access this particular page. I need to send the page to you in a secure way. If I encrypt it using my public key, you won’t be able to decrypt it because you don’t have my private key. And since you don’t have any public key of your own that I can use to encrypt the page for you here’s what I propose Since you can send me encrypted messages that only me can read (you have my public key), send me an encrypted message with an encryption key in it. Just make up a random encryption key that we’ll both use to encrypt and decrypt the messages between us during this session .

A simple symmetric key is enought. We’ll use the same key to encrypt and decrypt the messages.

  • So there’s no way that anybody with your public key can trick others to believe that he is you ?
  • Nope. That’s the beauty of the assymetric encryption.

When you send the public key to the victim’s contain your public key + a certificate that this public key belongs to you. If you are a website, then the certificate will contain the domain name of the website. Basically, a certificate says something like: the following public key “XYZ123” belongs to example.com.

that’s why we have “Certificate Authorities” like Verisign, Digicert or even Symantec. It is believed that these companies have the necessary trustworthiness to deliver certificates to different •entities. Think of a CA like a registrar for public keys. Just like registrars assert that a domain name belongs to a certain person or company, CAS assert that a public key belongs to a certain domain name (or IP address) .

The certificate will contain the CA that delivered it, but you don’t even have to check with them because the certificate is signed by them. That signature alone is enough proof that the certificate comes from them.

A signature is simply a small message that is encrypted with their private key. Since private keys are asymetric, that means that only the associated public key can decrypt it.

Asymmetric encryption works in both way. public -> private and private -> public. What the public key encrypts only the private key can decrypt, and what the private key can encrypt only the public key can decrypt.

for PKI, we’re not looking for secrecy here, we only want to prove that we’ re the real authors of the message. Suppose I send you the message “HELLO WORLD”, encrypted with my private key. The encrypted message would be, for example, “XYZ1234”. So you receive “XYZ1234” . If I give you my public key, you would be able to decrypt “XYZ1234” into “HELLO WORLD” . And by doing so, you would have proof that that message was sent by me, because the public key you used decrypts messages that were encrypted by my private key only. And since I am the only person in the universe who has that private key, that proves that I am the author of that message.

Really nice. So I don’t have to contact the CA to check the validity of the certificate, all I have to do is use their public key to decrypt the signature that’s in it. If it’s the same as err, wait, what should I compare the decrypted signature to again ?

You have to find the same hash as the one you have calculated. They are sending a small hash of the whole certificate. So what you have to do is to calculate the hash of the certificate yourself, then compare it to the hash you get when you decrypt the signature. If the two are the same that means two things

  1. The CA’s public key worked, so the signature was encrypted by the associated private key, which means the certificate was really issued by the CA.
  2. Since the hash is the same, it also means that you are seeing the exact same certificate that the CA delivered to the website you are visiting. The information contained inside hasn’t been tampered with.

That’s really good. So, let me recap one more time .

  1. I contact you for an HTTPS page.
  2. You send me an SSL certificate that contains your public key and a signature from the CA that delivered
  3. I make sure the certificate is valid by using the CA’s public key to decrypt the signature. In parallel, I also calculate the hash of the certificate.

If my hash and the one I got from decrypting the signature are equal, that means that the certificate was really issued by the CA and that I can be sure that the public key you sent me is really yours.

Because you implicitly trust the CA.

Let’s continue:

  1. I generate a random key that we’ll both use as a symmetric key to encrypt and decrypt the messages we’ll be sending each other.
  2. I encrypt this symmetric key with your public key and send it to you.
  3. You decrypt my message with your private key and find my secret key.
  4. Every request or response between us will be encrypted with this shared secret symmetric key.

CN

The Common Name (AKA CN) represents the server name protected by the SSL certificate.

The certificate is valid only if the request hostname matches the certificate common name.

To check the status, such as

sudo openssl x509 -noout -in xxx.com.cer -text

Subject: C=UK, ST=London, L=London, O=AAA Bank, OU=Product and Markets, CN=*.xxxtest.com Subject Public Key Info:

commonName format

The common name is not a URL. It doesn’t include any protocol (e.g. http:// or https://), port number, or pathname. For instance, https://example.com or example.com/path are incorrect. In both cases, the common name should be example.com

Common Name vs Subject Alternative Name

The common name can only contain up to one entry: either a wildcard or non-wildcard name. It’s not possible to specify a list of names covered by an SSL certificate in the common name field.

The Subject Alternative Name extension (also called Subject Alternate Name or SAN) was introduced to solve this limitation. The SAN allows issuance of multi-name SSL certificates.

SHA-2 SSL Certificates

Almost all certificates are currently signed with the SHA-2 hash algorithm.

This article provides a simple overview of the SHA-1 to SHA-2 transition plans, as well additional informations on the SHA-2 hash algorithm and SSL certificates purchased with DNSimple previous than September 2014.

The SHA family of hashing algorithms were developed by the National Institute of Standards and Technology (NIST) and are used by certificate authorities (CAs) when digitally signing issued certificates.

Reference

  • https://support.dnsimple.com/articles/what-is-ssl-certificate-chain/
  • https://www.thawte.com/resources/getting-started/how-ssl-works/

2022

Linux Tips

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

Back to Top ↑

2021

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 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...

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 I found a weird problem of the app Google Maps of my Oppo Android phone. That’s when you search a place in Google map, say “Central Park”, ideally th...

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...

Back to Top ↑

2020

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...

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/

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 ...

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...

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

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...

Back to Top ↑

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...

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...

Back to Top ↑

2018

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...

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.”

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...

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...

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 ...

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

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...

Agile and SCRUM

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

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...

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,...

Back to Top ↑

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...

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 ...

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

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

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 Security Notes

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

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...

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...

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

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...

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

Back to Top ↑

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...

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...

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...

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...

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...

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。

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。

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...

iConnect

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

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...

Something about authentication

It’s annoying to keep on repeating typing same login and password when you access multiple systems within office or for systems in external Internet. There a...

SQL

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

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 ...

Load Balancing

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

Python

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

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...

Back to Top ↑