Today's Question:  What does your personal desk look like?        GIVE A SHOUT

SEARCH KEYWORD -- Hash

  Translating math into code with examples in Java, Racket, Haskell and Python

Discrete mathematical structures form the foundation of computer science.These structures are so universal that most research papers in the theory of computation, programming languages and formal methods present concepts in terms of discrete mathematics rather than code.The underlying assumption is that the reader will know how to translate these structures into a faithful implementation as a working program.A lack of material explaining this translation frustrates outsiders.What deepens that fr...

   Math,Algorithms,Formula,Program,Python     2011-11-14 08:43:15

  Becoming a Better Developer, Part 2: Know Your Core Competencies

If you're trying to grow your startup you've come to the right place. Get my 170-page ebook on how to grow a startup and join thousands of self-funded entrepreneurs by subscribing to my newsletter at right. For years business consultants have instructed businesses to “know your core competencies.” What this means is “know what you do well and stick to it.” For example: Harley Davidson makes great motorcycles. But they’re probably not so good at making per...

   Developer,Tips     2011-06-29 08:40:10

  Understand diff in Unix

diff is an important tool program in Unix. It is used to compare differences of two files, it is the foundation for code version control. If you type : $ diff <file_before_change> <file_after_change> diff will tell you what's the difference between these two files. The result may not be so easy to understand, so now I will show you how to understand diff. 1. 3 formats of diff diff has 3 formats due to historic reasons. normal diff context diff unified diff 2. Demo files For easy d...

   diff,Unix,version control,git     2012-09-03 10:49:36

  Additional steps need to implement to setup shadow-boxV2 OPTEE on Raspberry PI

We followed the Shadow-box v2 project from the https://github.com/kkamagui/shadow-box-for-arm to set up the trustZone on Raspberry PI modeB to protect the Linux Kernel. But got a problem when doing the step: [3.6.5. Activate Shadow-Box for ARM and Start Secure Pi!] to create the hash for the memory area. The result is not shown. If you met the same problem, this is what I did to fix the problem on my PI: 1.1  When we do the step [3.5.1. Copy OP-TEE OS with Shadow-Box for ARM and N...

   HARDWARE,RASPBERRY PI     2019-05-20 08:52:55

  How Query Optimizer Works in RDBMS

In a previous post, we discussed how the various relational operators are implemented in relational database systems. If you have read that post, you probably still remember that there are a few alternative implementations for every operator. Thus, how should RDBMS determine which algorithm (or implementation) to use? Obviously, to optimize the performance for any query, RDBMS has to select the correct the algorithm based on the query. It would not be desirable to always use the same algori...

   DATABASE,DATABASE DESIGN,DATABASE OPTIMIZATION     2019-04-20 07:26:32

  4 ways to obtain access token in OAuth 2.0

OAuth 2.0 is an authorization mechanism, it's ,mainly used for issuing access token. There are 4 ways to obtain access token as per RFC 6749. Authorization code Implicit Password Client credentials The third party application must obtain a client id and client secret from the target service before obtaining access token no matter which method to use. This is to prevent token to be used maliciously. Authorization code With this method, the third party application must first get an authorization...

   OAUTH2,ACCESS TOKEN,REFRESH TOKEN     2019-06-29 07:12:03

  How To Optimize Your Site With HTTP Caching

I’ve been on a web tweaking kick lately: how to speed up your javascript, gzip files with your server, and now how to set up caching. But the reason is simple: site performance is a feature. For web sites, speed may be feature #1. Users hate waiting, we get frustrated by buffering videos and pages that pop together as images slowly load. It’s a jarring (aka bad) user experience. Time invested in site optimization is well worth it, so let’s dive in. What is Caching? ...

   Website performance,Speed,HTTP Cache,Hash code     2011-12-10 06:11:33

  One thought about JavaScript exception handle

Due to network, browser and cache issues, the JS executed in production may produce different results from the testing environments. Sometimes they may produce exceptions. Front-end developers may encounter this kind of exceptions frequently. But how to log and use them is seldomly considered by them. Actually, exception handling includes two steps : log and use. 1. Log Regarding to log error, this is relatively convenient, since in each browser, there is one interface called window.onerror. win...

   JaavScript,Log,Exception,Email     2013-03-18 12:50:21

   Move.Me Writing Your Own WebSocket Server

The WebSocket protocol has applications beyond plain vanilla web development.  I will explain how the protocol works, how to implement your own server and share some insights I had along the way. Before we get down and dirty, I will explain what I’ve been doing with it. At this point I expect many of you are saying “I’m not working on a web game this doesn’t seem relevant to me.” Well, neither am I. I embed a WebSocket server into my game engine and wit...

   Socket,NetWorking,WebSocket,Server development     2012-01-28 07:06:43

  CASSANDRA data model

Cassandra is an open source distributed database, it combines dynamic key/value and column oriented feature of Bigtable. Features of Cassandra are: Flexible schema, no need to design schema first, it's very convenient to add or delete strings Support range search on keys High usability, extensible. The single node error will not affect the cluster. We can think Cassandra's data model as a 4 or 5 dimensional Hash. COLUMN Columns is the smallest data unit in Cassandra, it is a 3 dimensional data...

   Cassandra,database,sort     2013-06-08 22:07:40

RECENT