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  Ways to check existence of JavaScript object

The design of JavaScript is not so sophisticated. It's very easy for us to make mistakes if we are not very careful when using JavaScript. For example, to check the existence of JavaScript object. Now we want to check whether a global object myObj exists or not, if it doesn't exist, we declare it. The pseudo code for this is : if(myObj not exist){ declare myObj; } You may think it's very easy to write the code. In fact, it is much more difficult than we may think. Juriy Zaytsev says there are m...

   JAVASCRIPT,OBJECT,EXISTENCE     2020-09-12 02:14:02

  An experience of fixing a memory-corruption bug

During the last 4 months, I was disturbed by a memory-corruption bug, and this bug will cause program crash. Until last Monday, I found the root cause and fixed it. This debug process is a difficult but memorable experience, so I will share it in this article.   My program works as a SMS Hub. When it receives a SMS, it will allocate a structure in heap memory like this: typedef struct { ...... int *a[8]; ...... } info; After processing the SMS, the program will free the m...

   c, debug, unix, solaris, multi-thread     2014-05-04 03:52:43

  Are NSA engineers better than engieers at Microsoft?

NSA is the US government department which takes care of the information and data security of US. It's said to be one of the largest of U.S. intelligence organizations in terms of personnel and budget. There are many excellent engineers working on information and data security and developing algorithms and software help US government to collect intelligence information from all around the world. Many people may be curious about whether NSA has better engineers than IT companies like Microsoft and...

   NSA,Microsoft     2014-01-09 07:24:43

  Different types of keystore in Java -- PKCS12

PKCS12 is an active file format for storing cryptography objects as a single file. It can be used to store secret key, private key and certificate.It is a standardized format published by RSA Laboratories which means it can be used not only in Java but also in other libraries in C, C++ or C# etc. This file format is frequently used to import and export entries from or to other keystore types. Next we will explain the operations which can be performed on PKCS12 keystore. Create PKCS12 keystore Be...

   Java, PKCS12, keystore, tutorial     2015-01-04 21:08:49

  Android socket programming example

Socket is a kind of interface for different sides t communicate, it usually identified by an IP and a port. There are many server side software on a server and they would provide different service. Each server many create some sockets and bind them to some ports so that clients can listen to. Software on the Internet will exchange data though a bidirectional connection established. Each end of the connection has a socket created. In Java, Socket and ServerSocket are in java.net package, ServerSo...

   Android,Socket,Java     2013-05-11 22:17:16

  Be careful about nil check on interface in GoLang

nil check is frequently seen in GoLang code especially for error check since GoLang's special error handling convention. In most cases, nil check is straight forward, but in interface case, it's a bit different and special care needs to be taken. Take a look at below code snippet and guess what the output will be. package main import ( "bytes" "fmt" "io" ) func check(w io.Writer) { if w != nil { fmt.Println("w is not nil") } fmt.Printf("w is %+v\n", w) } func main() { var b *bytes.B...

   INTERFACE,GOLANG,NIL CHECK,NIL TYPE,NIL VALUE     2019-04-06 07:47:07

  Can API be copyrighted? At least Oracle hopes so

  The result of the lawsuit case war between Oracle and Google is clearer now. The court said that 9 lines of code of Android has violated intellectual property right, these 9 lines of code can be ignored relative to the number of codes for the whole Android system. But just like LinuxToy points out that the reasons why this case catches so much attention are : 1). The amount of money Oracle asked from Google is $1 billion; 2). The statement says Java language itself doesn't violate the int...

   Oracle,Google,API,Copyright,Lawsuit case     2012-05-11 00:47:58

  var in JavaScript

Geoff published an article sometime ago--"How one missing var ruined our launch". This article described one case where MelonCard uses Node.js as their backend system, suddenly there was a small registration peak period--50-100 people registered concurrently, then the entire website stopped responding and many other strange problems showed up. When they were investigating the source of the problem, they found one missing var in the following code.app.all(‘/apps/:user_id/status’, fun...

   JavaScript,Scope,variable     2012-05-26 12:35:36

  Restore mocked variables in GoLang unit test

One of the guarding principles of writing unit test is that there should be no real external calls for dependant services. Unit test should run by its own and can run without issues on any environment including local, build, test environment. This indicates there should be some mock responses whenever an external call is needed so that different unit test scenarios can be covered. How can this be done in GoLang? In GoLang, anything can be assigned to a variable even including functions. A variab...

   GOLANG,UNIT TEST,MOCK FUNCTION,RESTORE MOCK     2021-12-10 20:43:00

  Canonicalize XML in Java

XML canonicalization is often used when there is need to create digital signature to be sent to peers for verification. Since digital signature is created based on XML data, the XML data has to be canonicalized before its signature value can be calculated. Even an extra space may affect the signature value calculated, hence it must follow some rules to canonicalize the XML data so that it has a standard format. This is why W3C created specification Canonical XML Version 1.1. This specificat...

   JAVA,XML,JAVA SECURITY     2016-01-20 01:39:45

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