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  • Looking for good SIP Book

    - by Dave
    Hey guys I am looking for a SIP book similar to this one on XMPP - Professional XMPP Programming with Javascript and Jquery (http://www.amazon.com/Professional-Programming-JavaScript-jQuery-Programmer/dp/0470540710) I am new to the area and any resources would be appreciated, thanks

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  • What is the most efficient way to learn x86 assembly?

    - by Web Des
    I want to learn x86 assembly and I want to know if learning reverse engineering is a good way to learn it? Also I have some c++ knowledge of pointers, stack, heap , references, etc.. I was considering this book. http://www.amazon.com/Reversing-Secrets-Engineering-Eldad-Eilam/dp/0764574817/ref=sr_1_1?s=books&ie=UTF8&qid=1340420512&sr=1-1&keywords=reverse+engineering Also Is reverse engineering the same as what they call disassembly?

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  • Which data structures and algorithms book should I buy?

    - by Hei
    I know C and C++ and I have some experience with Java, but I don't know too much about Algorithms and Data Structures. I did a search on Amazon, but I don't know what book should I choose. I don't want a book which put its basis only on the theoretic part; I want the practical part too (probably more than the theoretical one :) ). I don't want the code to be implemented in a certain language, but if is in Java, probably I would happier. :)

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  • How to backup data stored with Core Data - iPhone app?

    - by Alex
    I'm using sqlite for the persistent store, so could I just upload the .sqlite file to, for example, Amazon S3 as a way of providing users with the ability to backup their app data? Then for restoring just download it back and replace the existing .sqlite file in the app's folder. Does anybody see any issues with that? Has anyone done it? Any other suggestions on how to implement data backup feature?

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  • What are the best ways to scale small business applications ?

    - by Rachel
    I have one small online sale business but I want to make it scalable at limited expense and so am looking out at various services which can help me make my business scalable. I was looking into Amazon Web Services and it seems to be a viable option. Are there any other ways for adding scalability to small online businesses ?

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  • Reverse a given sentence in java

    - by giri
    This was the question asked me in amazon interview. I could not solve the problem properly, Write a program to reverse a given sentence like "This is interview question" the output must be "question interview is this".Can any tell me how to get this done? Thanks in advance

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  • Professional way to write project documentation

    - by EugeneP
    What tools and standards do you use to describe your project, database, modules, classes, their interaction for programmers, let's say after the project is finished. Do you use UML? Are there enterprise standards for Java developers, how to write such a documentation let's say from SUN? Are there specific tools that simplify this documentation process & compilation of neccessary docs. If there are good books on project documenting process, please give me links to Amazon.

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  • Oracle for the SQL Server DBA guides?

    - by MattK
    I am looking for a reference for a SQL Server DBA who has to come up to speed on basic Oracle 11 DBA tasks: backup, recovery, user administration, etc. There seems to be some material on the web for the reverse: Oracle - SQL Server, but the only potentially useful resource I have found in a few searches is yet to be published: http://www.amazon.com/Oracle-Database-Administration-Microsoft-Osborne/dp/0071744312 Can anyone provide references to something currently available?

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  • Is there any NHibernate book?

    - by Przemek
    Taking into consideration that NHibernate has been available for some time I thought that there would be a book available already. A search on amazon turned out just one that apparently has been delayed (Manning). Meanwhile, it looks that there seems to be coming many books on Microsoft Entity Framework. Is there any significance in that?

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  • Oracle for the SQL Server books?

    - by MattK
    I am looking for a reference for a SQL Server DBA who has to come up to speed on basic Oracle 11 DBA tasks: backup, recovery, user administration, etc. There seems to be some material on the web for the reverse: Oracle - SQL Server, but the only potentially useful resource I have found in a few searches is yet to be published: http://www.amazon.com/Oracle-Database-Administration-Microsoft-Osborne/dp/0071744312 Can anyone provide references to something currently available?

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  • Advantages of SQLServer vs. MySQL for C#/.NET4 Cloud Applications

    - by Ed Eichman
    I am considering building several C#/.NET4 applications all using a central, cloud based database. In addition, several LAMP (MySQL) web shops will be accessing the cloud DB. MySQL is the database that I'm most familiar with, and my default selection for the cloud DB would be MySQL on Amazon or Joyent. However, I was wondering what development "extras" are available for SQLServer in VisualStudio 2010 that are not available for MySQL. Are there any "killer features" that should make me consider SQLServer instead of MySQL?

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  • How does one mirror a maven repository?

    - by Randy
    Our company would like to mirror our Maven 2 Repository inside of the Amazon network. What software should one use to do this? We have looked into a Wagon-S3 but that sort of functionality is not desirable... we want the artifacts to already be present when we are ready for a build.

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  • Differences between Zend Framework 1.8 and 1.10

    - by Pat
    I want to start learning Zend Framework. My only concern is that the most recent ZF book on Amazon with good reviews teaches version 1.8 of the framework, which is now about a year old. Do you think it would be a good idea to still pick up that book or is it too old now?

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  • Moving .JS files to a CDN: How to manage AJAX requests?

    - by pagewil
    I am thinking of moving my static .JS files to a CDN such as Amazon S3 for performance reasons. As my PHP files and mySQL DB remain on my primary hosting domain what is the best way to manage my JS AJAX requests if they are now cross domain? Currently they look like this within my .JS file (with relative paths): $.ajax({ type: "POST", url: "/myNearbyPhpFile.php", data: {data:someData}, success: function($r){} });

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  • use javascript to read a link resource without ajax

    - by user156153
    Not sure if it's possible but how do I read a resource from a url using javascript without ajax? for example, the following url is a static text file containing json encoded text http://mysite.s3.amazonaws.com/jsonencodedcontent.txt I'd like to use javascript to read the content from above link, read the json content into a javascript variable. I can't use ajax because of cross site and I have no control over amazon S3 domain. anyway to achieve this?

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  • 301 Redirect. Need help. Having a hard time.

    - by Soma
    I'm trying to use mod_rewrite to redirect URLs and can't get anything to work. Here is what I'm hoping to do: Old URL: http://www.example.com/asp.pl?%5Fpuri=astore.amazon.com%2Fthegi02-20%2Fdetail%2FB0001L0DFA%2Fassid Needs to redirect to: www.example.com Anyone know of any way to do that?

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  • Unlimited Online File Storage

    - by AmeL
    Well, I would like to build a file hosting website just like other already did, but it is going to be something different by adding search engine, allowing download and upload in full speed for any user, and so on. Unfortunately the web hosting plans, which declared to support UNLIMITED SPACE rarely allows me to host files on those space. So what I need is the unlimited file storage service which could host all of my users' files. I found Amazon S3, already provides such service, but could anybody recommends me for other better ?

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  • Enums in java compile error

    - by London
    Hi, I'm trying to learn java from bottom up, and I got this great book to read http://www.amazon.com/o/ASIN/0071591060/ca0cc-20 . Now I found example in the book about declaring Enums inside a class but outside any methods so I gave it a shot : Enum CoffeeSize { BIG, HUGE, OVERWHELMING }; In the book its spelled enum and I get this compile message Syntax error, insert ";" to complete BlockStatements Are the Enums that important at all?I mean should I skip it or its possible that I will be using those some day?

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  • Facebook application development resources

    - by Michael
    What is the most efficient way to start learning develop Facebook applications? Any web resource or book that you would recommend to start from? Any MUST READ or Bibles available for this? There are plenty of them in Amazon, but which one really worth to spend time? What kind of development technologies are used in this? Is PHP/MySQL/JS enough to jump in? Thanks

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  • Strange DNS issue with internal Windows DNS

    - by Brady
    I've encountered a strange issue with our internal Windows DNS infrastructure. We have a website hosted on Amazon EC2 with the DNS running on Amazon Route 53. In the publicly facing DNS we have the wildcard record setup as an A record Alias pointing to an AWS Elastic Load Balancer sitting in front of our EC2 instances. For those who are not aware, the A record Alias behaves like a CNAME record, however no extra lookup is required on the client side (See http://docs.amazonwebservices.com/Route53/latest/DeveloperGuide/CreatingAliasRRSets.html for more information). We have a secondary domain that has the www subdomain as a CNAME pointing to a subdomain on the primary domain, which resolves against the wildcard entry. For example the subdomain www.secondary.com is a CNAME to sub1.primary.com, but there is no explicit entry for sub1.primary.com, so it resolves to wildcard record. This setup work without issue publicly. The issue comes in our internal DNS at our corporate office where we use the same primary domain for some internal only facing sites. In this setup we have two Active Directory DNS servers with one Server 2003 and one Server 2008 R2 instance. The zone is an AD integrated zone, but it is not the AD domain. In the internal DNS we have the wildcard record pointing to a third external domain, that is also hosted on Route 53 with an A record Alias pointing to the same ELB instance. For example, *.primary.com is a CNAME to tertiary.com, so in effect you have www.secondary.com as a CNAME to *.primary.com, which is a CNAME to tertiary.com. In this setup, attempting to resolve www.secondary.com will fail. Clearing the cache on the Server 2003 instance will allow it to resolve once, but subsequent attempts will fail. It fails even with a clean cache against the 2008 R2 server. It seems that only Windows clients are affected. A Mac running OSX Mountain Lion does not experience this issue. I'm even able to replicate the issue using nslookup. Against the 2003 server, with a freshly cleaned cache, I recieve the appropriate response from www.secondary.com: Non-authoritative answer: Name: subdomain.primary.com Address: x.x.x.x (Public IP) Aliases: www.secondary.com Subsequent checks simply return: Non-authoritative answer: Name: www.secondary.com If you set the type to CNAME you get the appropriate responses all the time. www.secondary.com gives you: Non-authoritative answer: www.secondary.com canonical name = subdomain.primary.com And subdomain.primary.com gives you: subdomain.primary.com canonical name = tertiary.com And setting type back to A gives you the appropriate response for tertiary.com: Non-authoritative answer: Name: tertiary.com Address: x.x.x.x (Public IP) Against the 2008 R2 server things are a little different. Even with a clean cache, www.secondary.com returns just: Non-authoritative answer: Name: www.secondary.com The CNAME records are returned appropriately. www.secondary.com returns: Non-authoritative answer: www.secondary.com canonical name = subdomain.primary.com And subdomain.primary.com gives you: subdomain.primary.com canonical name = tertiary.com tertiary.com internet address = x.x.x.x (Public IP) tertiary.com AAAA IPv6 address = x::x (Public IPv6) And setting type back to A gives you the appropriate response for tertiary.com: Non-authoritative answer: Name: tertiary.com Address: x.x.x.x (Public IP) Requests directly against subdomain.primary.com work correctly.

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  • Week in Geek: USDA Chooses Microsoft for Cloud Services Edition

    - by Asian Angel
    This week we learned how to create geeky LED holiday lights with old bottles, dig deeper in Windows Defrag via the command prompt, use Google Chrome’s drag/drop feature to upload files easier, find great gift recommendations by looking through the How-To Geek holiday gift guide, and have fun adding Merry Christmas fonts to our computers. Photo by ntr23. Random Geek Links It has been a busy week, so we have extra news link goodness with information that is good for you to know. USDA making the move to Microsoft The U.S. Department of Agriculture has announced that it has chosen Microsoft to host things like e-mail, instant messaging, and collaboration through the software giant’s Business Productivity Online Suite. Google says it was cut off from USDA project bid Google is claiming that it was not given a chance to bid on a cloud-computing project for the U.S. Department of Agriculture, for which the contract was awarded to rival Microsoft. Apache is being forced into a Java Fork When Oracle rolled over Apache and Google’s objections to its Java plans in December, the scene was set for Apache to leave and, eventually, force a Java code fork. Tumblr explains daylong outage After experiencing an outage that started on Sunday afternoon and stretched through most of the day yesterday, Tumblr has explained what happened. Google demos Chrome OS, launches pilot program During a press briefing this week in San Francisco, Google launched the Chrome application store and demonstrated Chrome OS, its browser-centric netbook operating system. Don’t expect Spotify in U.S. this holiday season As of last week, Spotify had yet to sign a single licensing deal with a major label, after spending more than a year negotiating, multiple music sources told CNET. December 2010 Patch Tuesday will come with most bulletins ever According to the Microsoft Security Response Center, Microsoft will issue 17 Security Bulletins addressing 40 vulnerabilities on Tuesday, December 14. It will also host a webcast to address customer questions the following day. Hacker plants back door in Symbian firmware Indian hacker Atul Alex has had a look at the firmware for Symbian S60 smartphones and come up with a back door for it. PC quarantines raise tough complexities The concept of quarantining PCs to prevent widespread infection is “interesting, but difficult to implement, with far too many problems”, said security experts. Symantec: DDoS attacks hard to defend It has surfaced that the distributed denial of service (DDoS) attacks on Visa and MasterCard Web sites on Wednesday were carried out by a toolkit known as low orbit ion cannon (LOIC). Web Sockets and the risks of unfinished standards Enthusiasm for a promising new standard called Web Sockets has quickly cooled in some quarters as a potential security problem led some browser makers to hastily postpone support. Internet Explorer 9 to get tracking protection Microsoft is making changes to Internet Explorer 9’s security features that will better enable users to keep sites from tracking their activity across browsing sessions. NASA sold PCs with sensitive data NASA failed to remove sensitive data from computers that it sold, according to an audit report released this week. Cybercrooks create fake Amazon receipts The bad guys have created yet another online scam, this one involving fake Amazon receipts. World of Warcraft character move fees waived Until December 22, Blizzard will allow free realm transfers from 25 highly populated servers to alleviate log-in queues or performance issues. (The free transfers are one-way and one-time only.) SpaceX Dragon reaches orbit atop a Falcon with a fiery tail The Space Exploration Technologies corporation has become the first nongovernmental entity to put a vehicle into low Earth orbit. Geek Video of the Week If birds have wings, then why are the Angry Birds using slingshots? Photo by Dorkly Bits. Wait… Birds have Wings, Why are the Angry Ones Using Slingshots? Sysadmin Geek Tips How To Setup Email Alerts on Linux Using Gmail or SMTP Linux machines may require administrative intervention in countless ways, but without manually logging into them how would you know about it? Here’s how to setup emails to get notified when your machines want some tender love and attention. Random TinyHacker Links Red Panda Webcam Support Firefox and the Knoxville Zoo’s Red Panda program. Christmas Icons (Icons we like) Superb set of holiday icons by lgp85 at deviantArt. Download the .zip and use as .png or convert to .ico at Convertico.com or with tiny app Imagicon. Super User Questions Enjoy reading the great answers to this week’s popular questions from Super User Useful USB boot disks? DVD/CD burning .zip: is it more reliable, faster, longer lasting to burn a zip of files rather than the files as a folder? What are other ways to backup my files if I do not have an external drive? Anti virus what is the difference between these all? How can I block all Facebook elements/content? How-To Geek Weekly Article Recap Have you had a busy week between work and preparing for the holidays? Get caught up on your HTG reading with our hottest articles of the week. 20 Windows Keyboard Shortcuts You Might Not Know The 50 Best Registry Hacks that Make Windows Better LCD? LED? Plasma? The How-To Geek Guide to HDTV Technology HTG Explains: Which Linux File System Should You Choose? How to Use and Customize Google Chrome Web Apps One Year Ago on How-To Geek This week’s batch of retro geeky goodness is all about customizing Windows 7. ClassicShell Adds Classic Start Menu and Explorer Features to Windows 7 Get an Aero-Styled Classic Start Menu in Windows 7 Customize the Windows 7 Logon Screen Get the Classic Style Network Activity Indicator Back in Windows 7 How To Enable Check Boxes for Items In Windows 7 The Geek Note We would like you to join us in welcoming Jason Fitzpatrick to the writing staff here at How-To Geek. He started with us this past week, so take some time to read through his articles about the Wii, Kindle, & PlayStation 2 Peripherals and leave a friendly comment to say “Hi”! Got a great tip to share? Make sure to send it in to us at [email protected]. Photo by real00. Latest Features How-To Geek ETC The 50 Best Registry Hacks that Make Windows Better The How-To Geek Holiday Gift Guide (Geeky Stuff We Like) LCD? LED? Plasma? The How-To Geek Guide to HDTV Technology The How-To Geek Guide to Learning Photoshop, Part 8: Filters Improve Digital Photography by Calibrating Your Monitor Our Favorite Tech: What We’re Thankful For at How-To Geek Settle into Orbit with the Voyage Theme for Chrome and Iron Awesome Safari Compass Icons Set Escape from the Exploding Planet Wallpaper Move Your Tumblr Blog to WordPress Pytask is an Easy to Use To-Do List Manager for Your Ubuntu System Snowy Christmas House Personas Theme for Firefox

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  • A Guided Tour of Complexity

    - by JoshReuben
    I just re-read Complexity – A Guided Tour by Melanie Mitchell , protégé of Douglas Hofstadter ( author of “Gödel, Escher, Bach”) http://www.amazon.com/Complexity-Guided-Tour-Melanie-Mitchell/dp/0199798109/ref=sr_1_1?ie=UTF8&qid=1339744329&sr=8-1 here are some notes and links:   Evolved from Cybernetics, General Systems Theory, Synergetics some interesting transdisciplinary fields to investigate: Chaos Theory - http://en.wikipedia.org/wiki/Chaos_theory – small differences in initial conditions (such as those due to rounding errors in numerical computation) yield widely diverging outcomes for chaotic systems, rendering long-term prediction impossible. System Dynamics / Cybernetics - http://en.wikipedia.org/wiki/System_Dynamics – study of how feedback changes system behavior Network Theory - http://en.wikipedia.org/wiki/Network_theory – leverage Graph Theory to analyze symmetric  / asymmetric relations between discrete objects Algebraic Topology - http://en.wikipedia.org/wiki/Algebraic_topology – leverage abstract algebra to analyze topological spaces There are limits to deterministic systems & to computation. Chaos Theory definitely applies to training an ANN (artificial neural network) – different weights will emerge depending upon the random selection of the training set. In recursive Non-Linear systems http://en.wikipedia.org/wiki/Nonlinear_system – output is not directly inferable from input. E.g. a Logistic map: Xt+1 = R Xt(1-Xt) Different types of bifurcations, attractor states and oscillations may occur – e.g. a Lorenz Attractor http://en.wikipedia.org/wiki/Lorenz_system Feigenbaum Constants http://en.wikipedia.org/wiki/Feigenbaum_constants express ratios in a bifurcation diagram for a non-linear map – the convergent limit of R (the rate of period-doubling bifurcations) is 4.6692016 Maxwell’s Demon - http://en.wikipedia.org/wiki/Maxwell%27s_demon - the Second Law of Thermodynamics has only a statistical certainty – the universe (and thus information) tends towards entropy. While any computation can theoretically be done without expending energy, with finite memory, the act of erasing memory is permanent and increases entropy. Life & thought is a counter-example to the universe’s tendency towards entropy. Leo Szilard and later Claude Shannon came up with the Information Theory of Entropy - http://en.wikipedia.org/wiki/Entropy_(information_theory) whereby Shannon entropy quantifies the expected value of a message’s information in bits in order to determine channel capacity and leverage Coding Theory (compression analysis). Ludwig Boltzmann came up with Statistical Mechanics - http://en.wikipedia.org/wiki/Statistical_mechanics – whereby our Newtonian perception of continuous reality is a probabilistic and statistical aggregate of many discrete quantum microstates. This is relevant for Quantum Information Theory http://en.wikipedia.org/wiki/Quantum_information and the Physics of Information - http://en.wikipedia.org/wiki/Physical_information. Hilbert’s Problems http://en.wikipedia.org/wiki/Hilbert's_problems pondered whether mathematics is complete, consistent, and decidable (the Decision Problem – http://en.wikipedia.org/wiki/Entscheidungsproblem – is there always an algorithm that can determine whether a statement is true).  Godel’s Incompleteness Theorems http://en.wikipedia.org/wiki/G%C3%B6del's_incompleteness_theorems  proved that mathematics cannot be both complete and consistent (e.g. “This statement is not provable”). Turing through the use of Turing Machines (http://en.wikipedia.org/wiki/Turing_machine symbol processors that can prove mathematical statements) and Universal Turing Machines (http://en.wikipedia.org/wiki/Universal_Turing_machine Turing Machines that can emulate other any Turing Machine via accepting programs as well as data as input symbols) that computation is limited by demonstrating the Halting Problem http://en.wikipedia.org/wiki/Halting_problem (is is not possible to know when a program will complete – you cannot build an infinite loop detector). You may be used to thinking of 1 / 2 / 3 dimensional systems, but Fractal http://en.wikipedia.org/wiki/Fractal systems are defined by self-similarity & have non-integer Hausdorff Dimensions !!!  http://en.wikipedia.org/wiki/List_of_fractals_by_Hausdorff_dimension – the fractal dimension quantifies the number of copies of a self similar object at each level of detail – eg Koch Snowflake - http://en.wikipedia.org/wiki/Koch_snowflake Definitions of complexity: size, Shannon entropy, Algorithmic Information Content (http://en.wikipedia.org/wiki/Algorithmic_information_theory - size of shortest program that can generate a description of an object) Logical depth (amount of info processed), thermodynamic depth (resources required). Complexity is statistical and fractal. John Von Neumann’s other machine was the Self-Reproducing Automaton http://en.wikipedia.org/wiki/Self-replicating_machine  . Cellular Automata http://en.wikipedia.org/wiki/Cellular_automaton are alternative form of Universal Turing machine to traditional Von Neumann machines where grid cells are locally synchronized with their neighbors according to a rule. Conway’s Game of Life http://en.wikipedia.org/wiki/Conway's_Game_of_Life demonstrates various emergent constructs such as “Glider Guns” and “Spaceships”. Cellular Automatons are not practical because logical ops require a large number of cells – wasteful & inefficient. There are no compilers or general program languages available for Cellular Automatons (as far as I am aware). Random Boolean Networks http://en.wikipedia.org/wiki/Boolean_network are extensions of cellular automata where nodes are connected at random (not to spatial neighbors) and each node has its own rule –> they demonstrate the emergence of complex  & self organized behavior. Stephen Wolfram’s (creator of Mathematica, so give him the benefit of the doubt) New Kind of Science http://en.wikipedia.org/wiki/A_New_Kind_of_Science proposes the universe may be a discrete Finite State Automata http://en.wikipedia.org/wiki/Finite-state_machine whereby reality emerges from simple rules. I am 2/3 through this book. It is feasible that the universe is quantum discrete at the plank scale and that it computes itself – Digital Physics: http://en.wikipedia.org/wiki/Digital_physics – a simulated reality? Anyway, all behavior is supposedly derived from simple algorithmic rules & falls into 4 patterns: uniform , nested / cyclical, random (Rule 30 http://en.wikipedia.org/wiki/Rule_30) & mixed (Rule 110 - http://en.wikipedia.org/wiki/Rule_110 localized structures – it is this that is interesting). interaction between colliding propagating signal inputs is then information processing. Wolfram proposes the Principle of Computational Equivalence - http://mathworld.wolfram.com/PrincipleofComputationalEquivalence.html - all processes that are not obviously simple can be viewed as computations of equivalent sophistication. Meaning in information may emerge from analogy & conceptual slippages – see the CopyCat program: http://cognitrn.psych.indiana.edu/rgoldsto/courses/concepts/copycat.pdf Scale Free Networks http://en.wikipedia.org/wiki/Scale-free_network have a distribution governed by a Power Law (http://en.wikipedia.org/wiki/Power_law - much more common than Normal Distribution). They are characterized by hubs (resilience to random deletion of nodes), heterogeneity of degree values, self similarity, & small world structure. They grow via preferential attachment http://en.wikipedia.org/wiki/Preferential_attachment – tipping points triggered by positive feedback loops. 2 theories of cascading system failures in complex systems are Self-Organized Criticality http://en.wikipedia.org/wiki/Self-organized_criticality and Highly Optimized Tolerance http://en.wikipedia.org/wiki/Highly_optimized_tolerance. Computational Mechanics http://en.wikipedia.org/wiki/Computational_mechanics – use of computational methods to study phenomena governed by the principles of mechanics. This book is a great intuition pump, but does not cover the more mathematical subject of Computational Complexity Theory – http://en.wikipedia.org/wiki/Computational_complexity_theory I am currently reading this book on this subject: http://www.amazon.com/Computational-Complexity-Christos-H-Papadimitriou/dp/0201530821/ref=pd_sim_b_1   stay tuned for that review!

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  • Is Berkeley DB a NoSQL solution?

    - by Gregory Burd
    Berkeley DB is a library. To use it to store data you must link the library into your application. You can use most programming languages to access the API, the calls across these APIs generally mimic the Berkeley DB C-API which makes perfect sense because Berkeley DB is written in C. The inspiration for Berkeley DB was the DBM library, a part of the earliest versions of UNIX written by AT&T's Ken Thompson in 1979. DBM was a simple key/value hashtable-based storage library. In the early 1990s as BSD UNIX was transitioning from version 4.3 to 4.4 and retrofitting commercial code owned by AT&T with unencumbered code, it was the future founders of Sleepycat Software who wrote libdb (aka Berkeley DB) as the replacement for DBM. The problem it addressed was fast, reliable local key/value storage. At that time databases almost always lived on a single node, even the most sophisticated databases only had simple fail-over two node solutions. If you had a lot of data to store you would choose between the few commercial RDBMS solutions or to write your own custom solution. Berkeley DB took the headache out of the custom approach. These basic market forces inspired other DBM implementations. There was the "New DBM" (ndbm) and the "GNU DBM" (GDBM) and a few others, but the theme was the same. Even today TokyoCabinet calls itself "a modern implementation of DBM" mimicking, and improving on, something first created over thirty years ago. In the mid-1990s, DBM was the name for what you needed if you were looking for fast, reliable local storage. Fast forward to today. What's changed? Systems are connected over fast, very reliable networks. Disks are cheep, fast, and capable of storing huge amounts of data. CPUs continued to follow Moore's Law, processing power that filled a room in 1990 now fits in your pocket. PCs, servers, and other computers proliferated both in business and the personal markets. In addition to the new hardware entire markets, social systems, and new modes of interpersonal communication moved onto the web and started evolving rapidly. These changes cause a massive explosion of data and a need to analyze and understand that data. Taken together this resulted in an entirely different landscape for database storage, new solutions were needed. A number of novel solutions stepped up and eventually a category called NoSQL emerged. The new market forces inspired the CAP theorem and the heated debate of BASE vs. ACID. But in essence this was simply the market looking at what to trade off to meet these new demands. These new database systems shared many qualities in common. There were designed to address massive amounts of data, millions of requests per second, and scale out across multiple systems. The first large-scale and successful solution was Dynamo, Amazon's distributed key/value database. Dynamo essentially took the next logical step and added a twist. Dynamo was to be the database of record, it would be distributed, data would be partitioned across many nodes, and it would tolerate failure by avoiding single points of failure. Amazon did this because they recognized that the majority of the dynamic content they provided to customers visiting their web store front didn't require the services of an RDBMS. The queries were simple, key/value look-ups or simple range queries with only a few queries that required more complex joins. They set about to use relational technology only in places where it was the best solution for the task, places like accounting and order fulfillment, but not in the myriad of other situations. The success of Dynamo, and it's design, inspired the next generation of Non-SQL, distributed database solutions including Cassandra, Riak and Voldemort. The problem their designers set out to solve was, "reliability at massive scale" so the first focal point was distributed database algorithms. Underneath Dynamo there is a local transactional database; either Berkeley DB, Berkeley DB Java Edition, MySQL or an in-memory key/value data structure. Dynamo was an evolution of local key/value storage onto networks. Cassandra, Riak, and Voldemort all faced similar design decisions and one, Voldemort, choose Berkeley DB Java Edition for it's node-local storage. Riak at first was entirely in-memory, but has recently added write-once, append-only log-based on-disk storage similar type of storage as Berkeley DB except that it is based on a hash table which must reside entirely in-memory rather than a btree which can live in-memory or on disk. Berkeley DB evolved too, we added high availability (HA) and a replication manager that makes it easy to setup replica groups. Berkeley DB's replication doesn't partitioned the data, every node keeps an entire copy of the database. For consistency, there is a single node where writes are committed first - a master - then those changes are delivered to the replica nodes as log records. Applications can choose to wait until all nodes are consistent, or fire and forget allowing Berkeley DB to eventually become consistent. Berkeley DB's HA scales-out quite well for read-intensive applications and also effectively eliminates the central point of failure by allowing replica nodes to be elected (using a PAXOS algorithm) to mastership if the master should fail. This implementation covers a wide variety of use cases. MemcacheDB is a server that implements the Memcache network protocol but uses Berkeley DB for storage and HA to replicate the cache state across all the nodes in the cache group. Google Accounts, the user authentication layer for all Google properties, was until recently running Berkeley DB HA. That scaled to a globally distributed system. That said, most NoSQL solutions try to partition (shard) data across nodes in the replication group and some allow writes as well as reads at any node, Berkeley DB HA does not. So, is Berkeley DB a "NoSQL" solution? Not really, but it certainly is a component of many of the existing NoSQL solutions out there. Forgetting all the noise about how NoSQL solutions are complex distributed databases when you boil them down to a single node you still have to store the data to some form of stable local storage. DBMs solved that problem a long time ago. NoSQL has more to do with the layers on top of the DBM; the distributed, sometimes-consistent, partitioned, scale-out storage that manage key/value or document sets and generally have some form of simple HTTP/REST-style network API. Does Berkeley DB do that? Not really. Is Berkeley DB a "NoSQL" solution today? Nope, but it's the most robust solution on which to build such a system. Re-inventing the node-local data storage isn't easy. A lot of people are starting to come to appreciate the sophisticated features found in Berkeley DB, even mimic them in some cases. Could Berkeley DB grow into a NoSQL solution? Absolutely. Our key/value API could be extended over the net using any of a number of existing network protocols such as memcache or HTTP/REST. We could adapt our node-local data partitioning out over replicated nodes. We even have a nice query language and cost-based query optimizer in our BDB XML product that we could reuse were we to build out a document-based NoSQL-style product. XML and JSON are not so different that we couldn't adapt one to work with the other interchangeably. Without too much effort we could add what's missing, we could jump into this No SQL market withing a single product development cycle. Why isn't Berkeley DB already a NoSQL solution? Why aren't we working on it? Why indeed...

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