SEARCH KEYWORD -- file system


  A plugin to update last_error in Delayed Job

delayed_job is a process based asynchronous task processing gem which can be ran at background. It will fork the specified number of processes to execute the tasks asynchronously. The task status is usually stored in the database so that it can be easily integrated into a Rails application where asynchronous job execution is desired. Normally when a job fails to execute or error occurs, it would save the error into the database with the column last_error. Ideally all these will be handled b...

   RUBY,RUBY ON RAILS,DELAYED JOB,LAST_ERROR     2017-11-18 13:05:49

  Generate certificate with cRLDistributionPoints extension using OpenSSL

In an X509 certificate, the cRLDistributionPoints extension provides a mechanism for the certificate validator to retrieve a CRL(Certificate Revocation List) which can be used to verify whether the given certificate is revoked.   A cRLDistributionPoints extension can contain one or more DistributionPoints where the CRL can be retrieved from. Each DistributionPoint consists of three fields,each of which is optional: distributionPoint : it contains either a SEQUENCE of general...

   X509,OPENSSL,CERTIFICATE,CRLDISTRIBUTIONPOINT,EXTENSION     2015-10-22 03:41:11

  Access control in Java -- doPrivileged

Previously we have introduced how Java performs permission check to protect resource access. What if sometimes we need to give some class the temporary access to some resource which it initially doesn't have? AccessController provides six doPrivileged methods to fulfill this requirement. These six methods have below signatures : static T doPrivileged(PrivilegedAction action)static T doPrivileged(PrivilegedAction action, AccessControlContext context)static T doPrivileged(PrivilegedExceptionA...

   JAVA,SECURITY,DOPRIVILEGED     2016-03-08 05:46:42

  Why should we drop or reduce use of MD5?

MD5 is a frequently used one-way hash algorithm, it is commonly used in following situations: Check data integrity. We take hash of the data stored in two different places and compare them. If the hash results are the same, then there is no need to check the actual data. This utilizes the collision-resistant feature. Two different data block will have little chance that their hash values will be the same. Many data service providers use such technique to check repeated data to avoild repeating...

   MD5,Vulnerability,attack     2012-09-29 04:47:49

  Change password of postgres account in Postgres

When installing Postgres on Windows, there is some default account created for user to login. One of them is postgres, but we often don;t know what's the password for this account when we first login using this account. We need to change the password for this account. How to change it? Step 1. Modify the pg_hba.conffile Go to the /data/ and open the pg_hba.conf. # TYPE  DATABASE        USER            ...

   Postgres,password, user account     2013-03-04 01:51:02

  Responsive Web Design

With the popularity of 3G, more and more people are surfing the Internet using mobile phones. Mobile devices are becoming common devices for accessing internet. So web design faces a big challenge which is how to display the same webpage on different devices with different screen  resolutions.Screen resolution of mobile device are usually not very large, the width is below 600px, while PC usually has a resolution over 1000px. It is not an easy task to display the same content with satisfyin...

   CSS,Web design,Layout,Response web design     2012-05-03 06:59:40

  Samsung will release 10.1 inch Windows RT Tablet

Today, Samsung not only announced Galaxy Note â…¡, first Windows Phone 8 device Ativ S and camera EK-GC100 Galaxy equipped with Android 4.1 system, but also announced a Windows RT Tablet PC Samsung Ativ Tab.The 10.1-inch Samsung Ativ Tab has a resolution of 1366 x 768,1.5 GHz dual-core processor, 2G RAM, a 32/64G storage space, support for microSD memory expansion. Other configurations as well as the standard Wi-Fi and Bluetooth 4.0, support for USB 2.0, uHDMI and NFC.In addition, the table...

   Samsung,Windows 8,Tablet     2012-08-29 19:36:31

  Want to install 64 bit OS on VirtualBox?

By default, VirtualBox only allows to install 32 bit OS on it. But sometimes, 64 bit OS is wanted for specific uses such as running platform specific tests. To allow installing 64 bit OS on VirtualBox. Below information is needed. Here is the official documentation about 64 bit OS: VirtualBox supports 64-bit guest operating systems, even on 32-bit host operating systems, provided that the following conditions are met: You need a 64-bit processor with hardware virtualization support (see the ...

   VirtualBox,64 bit,hardware virtualization,Ubuntu     2014-11-08 03:52:07

  String intern in Java

In Java, == is used to compare whether two objects have the same memory location, equals() is usually used to compare whether two objects have the same time and the same state.  When comparing two strings, normally we just want to know whether they have same content, so we can choose equals(). But since String comparison is so frequently needed, Java has worked on the String class to make == workable when comparing two String literals. The String class maintains a pool of emp...

   JAVA,STRING     2016-04-10 03:35:25

  How does JGSS read Windows native TGT credential?

MS LSA is a protected subsystem that authenticates and logs users onto the local system. The user credential is stored at the native credential cache of LSA on Windows. This kind of credential is often used to authenticate the user to the server, one of the authentication methods is Kerberos. JGSS has provided a native interface which can read the native TGT credential and use it to get the TGS of a service. But how does JGSS read the native TGT credential? Here is a sample code for reading nati...

   KERBEROS,JGSS,MS LSA,NATIVE CREDENTIAL,TGT,SESSION KEY TYPE     2015-03-25 03:42:32

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