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  • Welcome to the BI & Analytics Pulse Blog

    - by jacqueline.coolidge(at)oracle.com
    In this blog, we'll be taking the pulse of the BI and Analytics market.   We get to meet people who involved in every aspect of the market --  customers that push the envelope and use BI in innovative ways, software developers, product managers, and sales teams in the field.  This sparks lots of ideas.  We'll share our experience and ideas and hope to generate discussion on topics that reflect what's going on in the market and where it will go next.  First topics will include, self-service BI and in memory analytics.   Let us know what you think is interesting. 

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  • OT: March Mdness 2011

    - by RickHeiges
    This past fall, I decided to take a break from Fantasy Football. Did I miss it? Yes to some extent. Fantasy Football can really eat up a lot of time. But - I still love March Madness (NCAA Men's Basketball Tourney). It doesn't take much time to pick out teams. Since you can't make any changes after the deadline and the computer keeps track of scoring/scenarios/etc, it is a fun thing that really takes a little time and can help you enjoy the games a bit more. Let's see how good you are at picking...(read more)

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  • How should I pronounce the :: and -> in PHP?

    - by Renesis
    When I read these lines aloud to someone: $controller->process(); UserManager::getInstance(); How should the -> and :: be pronounced? Reading the characters themselves in cumbersome and I don't know of any nicknames for them. Being a developer who is used to C-style syntax, I'd like to say "dot", but I'd like something that is easy to say and people can easily understand. It would also be good to know if there are any pronunciations that have become de-facto standards among teams of developers.

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  • OUAB Europe Globalization Topics

    - by ultan o'broin
    Pleased to announce that the Oracle Usability Advisory Board has added a globalization workgroup for 2011. This will be headed up my myself. The aims of this workgroup are: To understand how our customers use translated versions of applications To identify key international support, translation and localization-related usability issues in deployed applications To make recommendations to Oracle usability and development teams about meeting global customer usability requirements in current and future versions of our applications. Issues include: How international users use applications when working, ethnography opportunities, key cultural impacts on usability; multilingual feature usage, localization of forms and reports, language quality, extensibility, translation of user assistance, user-generated and rich-media content like UPK, and international mobile application opportunities. More details will be available on the usableapps.oracle.com website shortly.

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  • Odd company release cycle: Go Distributed Source Control?

    - by MrLane
    sorry about this long post, but I think it is worth it! I have just started with a small .NET shop that operates quite a bit differently to other places that I have worked. Unlike any of my previous positions, the software written here is targetted at multiple customers and not every customer gets the latest release of the software at the same time. As such, there is no "current production version." When a customer does get an update, they also get all of the features added to he software since their last update, which could be a long time ago. The software is highly configurable and features can be turned on and off: so called "feature toggles." Release cycles are very tight here, in fact they are not on a shedule: when a feature is complete the software is deployed to the relevant customer. The team only last year moved from Visual Source Safe to Team Foundation Server. The problem is they still use TFS as if it were VSS and enforce Checkout locks on a single code branch. Whenever a bug fix gets put out into the field (even for a single customer) they simply build whatever is in TFS, test the bug was fixed and deploy to the customer! (Myself coming from a pharma and medical devices software background this is unbeliveable!). The result is that half baked dev code gets put into production without being even tested. Bugs are always slipping into release builds, but often a customer who just got a build will not see these bugs if they don't use the feature the bug is in. The director knows this is a problem as the company is starting to grow all of a sudden with some big clients coming on board and more smaller ones. I have been asked to look at source control options in order to eliminate deploying of buggy or unfinished code but to not sacrifice the somewhat asyncronous nature of the teams releases. I have used VSS, TFS, SVN and Bazaar in my career, but TFS is where most of my experience has been. Previously most teams I have worked with use a two or three branch solution of Dev-Test-Prod, where for a month developers work directly in Dev and then changes are merged to Test then Prod, or promoted "when its done" rather than on a fixed cycle. Automated builds were used, using either Cruise Control or Team Build. In my previous job Bazaar was used sitting on top of SVN: devs worked in their own small feature branches then pushed their changes to SVN (which was tied into TeamCity). This was nice in that it was easy to isolate changes and share them with other peoples branches. With both of these models there was a central dev and prod (and sometimes test) branch through which code was pushed (and labels were used to mark builds in prod from which releases were made...and these were made into branches for bug fixes to releases and merged back to dev). This doesn't really suit the way of working here, however: there is no order to when various features will be released, they get pushed when they are complete. With this requirement the "continuous integration" approach as I see it breaks down. To get a new feature out with continuous integration it has to be pushed via dev-test-prod and that will capture any unfinished work in dev. I am thinking that to overcome this we should go down a heavily feature branched model with NO dev-test-prod branches, rather the source should exist as a series of feature branches which when development work is complete are locked, tested, fixed, locked, tested and then released. Other feature branches can grab changes from other branches when they need/want, so eventually all changes get absorbed into everyone elses. This fits very much down a pure Bazaar model from what I experienced at my last job. As flexible as this sounds it just seems odd to not have a dev trunk or prod branch somewhere, and I am worried about branches forking never to re-integrate, or small late changes made that never get pulled across to other branches and developers complaining about merge disasters... What are peoples thoughts on this? A second final question: I am somewhat confused about the exact definition of distributed source control: some people seem to suggest it is about just not having a central repository like TFS or SVN, some say it is about being disconnected (SVN is 90% disconnected and TFS has a perfectly functional offline mode) and others say it is about Feature Branching and ease of merging between branches with no parent-child relationship (TFS also has baseless merging!). Perhaps this is a second question!

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  • New MySQL 5.6 Developer Certification and Training

    - by Breanne Cooley
    For those of you who work with MySQL, we've got some great news for you! A wide range of Oracle MySQL teams, including training, engineering, sales consulting and members of MySQL Support, collected content for the new MySQL 5.6 Developer Certification exam. These team members assist developers and DBAs with MySQL questions on a daily basis. They understand what developers need to know to successfully develop applications against MySQL Server 5.6. The MySQL 5.6 Developer Certification Exam details are listed here.  Naturally, this certification process covers the same ground as Oracle's MySQL Training for Developers course, making it ideal for reviewing topics to help you pass the exam. More importantly, you will learn how to develop successful applications that use MySQL Server 5.6 as a data store.  -Diana Gray, Principal Curriculum Project Manager, Oracle University

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  • Reporting defects in Agile

    - by user3728779
    I am working in sprint. At the end of sprint I need to send a defect report per sprint. Considering the below scenario please let me know your views. Two teams(A & B) are working at different locations in Sprint-2 and I am a tester from Team-A and report the defects for the items developed by Team-A in each sprint Question 1. I reported few defects in Sprint-2 for the functionality developed by Team-B in previous sprint. Do I have to consider this as observation or defect and report to Team-A? 2. I reported 5 defects of Sprint-2 for the functionality developed by team-A. All the defects are fixed and closed by me in the same sprint. Before the end of sprint I observed 2 defects got reopened for some reason. Now the defect count should be 5 or 7(5+2) should be considered for this sprint? Thanks Khan

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  • Are Java certifications important for an architect role?

    - by Tahir Akram
    My this question is career path related. I want to know how much Java Certifications (SCJP, SCWCD and others) are important for an architect position. If a person posses a good experience in Java development and want to pursue his career on architect level, do you guys think he need to have certification on his CV. If he has never worked on lead developer roles? If you conducting my interview for an architect position. And I have worked as a Java web developer in different teams having 5 years of exp. Never lead any. And I am having certification badges on my CV. How can a developer make his career path towards being an architect in a team?

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  • Does one's native spoken language affect quality of code?

    - by Xepoch
    There is a school of thought in linguistics that problem solving is very much tied to the syntax, semantics, grammar, and flexibility of one's own native spoken language. Working with various international development teams, I can clearly see a mental culture (if you will) in the codebase. Programming language aside, the German coding is quite different from my colleagues in India. As well, code is distinctly different in Middle America as it is in Coastal America (actually, IBM noticed this years ago). Do you notice with your international colleagues (from ANY country) that coding style and problem solving are in-line with native tongues?

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  • Ubuntu has LTS and normal version now. Does Lubuntu have the same?

    - by Elysium
    I am wondering if this is the right place for this question, but if not...then the moderators will surely tell me so. Anyway....there is Ubuntu 12.04 LTS and the normal 12.10 version. Is that the same with Lubuntu? On their site, for some reason, they seem to be promoting the 12.10 version while for me an LTS is always more appealing. I am wondering if they have the same ideology as the Ubuntu team. UPDATE: Is it okay to talk about Lubuntu here at all? I understand that it is a flavour of Ubuntu...but still. Are they 2 very different teams?

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  • Free ASP.NET, Ajax, and IIS Web Camps

    My colleague James Senior (@jsenior) has organized some new Microsoft's Web Camps. These are free, two-day events that allow you to learn and build on the Microsoft Web Platform. At camp, you will hear from Microsoft experts on the latest components of the platform, including ASP.NET Web Forms, ASP.NET MVC, ASP.NET Ajax Library, Entity Framework, IIS and much more. Camps also provide the opportunity to get hands on with labs and get creative by building apps in teams. All this with Microsoft...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Shelving code in Team Foundation Server (TFS)

    - by Mel
    I'm pretty new at using TFS and I'd like to know how you or your team use the "shelve" function of tfs. We have the following guidelines in using TFS: - perform a "Get Latest" before you check in and try to build/compile - do not check in code that does not compile - at the end of the day, if your work is not complete/partially done, you should "shelve" your pending changes The first two make sense but I don't really get the last one. I asked my mgr and he said that its so he knows that you actually did some work for that day, which does kind of makes sense but still, I'm wondering what other teams use the "shelve" function for?

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  • svn vs git for the sole developer? [closed]

    - by nattyP
    If I am sole developer (I do not work in a team) working from my laptop (Windows OS and Linux VM) and backing up data to the cloud (Dropbox etc), then is git still better than svn for my version control needs? I was thinking not since I wont need any of git's distributed features. But is git such a better approach to version control that I should consider moving anyway? With so many articles saying how people are moving from svn to git? I was wondering, if they are talking about large or open projects with teams of developers vs the sole developer. What do you think?

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  • Topeka Dot Net User Group (DNUG) Meeting &ndash; April 6, 2010

    Topeka DNUG is free for anyone to attend! Mark your calendars now! SPEAKER: Troy Tuttle is a self-described pragmatic agilist, and Kanban practitioner, with more than a decade of experience in delivering software in the finance and health industries and as a consultant. He advocates teams improve their performance through pursuit of better practices like continuous integration and automated testing. Troy is the founder of the Kansas City Limited WIP Society and is a speaker at local area groups...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Algorithm to Solve Most of a Problem

    - by Mike G
    I need an Algorithm/Design Pattern that allows me to try to get the maximum number of rules followed. So I have a couple teams and I need to pair them with a referee and against each other into a round robin. There a rules on who can compete with who and who can judge who so I need to find the configuration that satisfies the most of these. Some rules are more important than others and are "worth more" when evaluating "what satisfies the most of them" There probably isn't a algorithm for this, but is there a design pattern that could help me maximize my chances of finding this configuration?

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  • How is architectural design done in an agile environment?

    - by B?????
    I have read Principles for the Agile Architect, where they defined next principles : Principle #1 The teams that code the system design the system. Principle #2 Build the simplest architecture that can possibly work. Principle #3 When in doubt, code it out. Principle #4 They build it, they test it. Principle #5 The bigger the system, the longer the runway. Principle #6 System architecture is a role collaboration. Principle #7 There is no monopoly on innovation. The paper says that most of the architecture design is done during the coding phase, and only system design before that. That is fine. So, how is the system design done? Using UML? Or a document that defines interfaces and major blocks? Maybe something else?

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  • NetBeans, JSF, and MySQL Primary Keys using AUTO_INCREMENT

    - by MarkH
    I recently had the opportunity to spin up a small web application using JSF and MySQL. Having developed JSF apps with Oracle Database back-ends before and possessing some small familiarity with MySQL (sans JSF), I thought this would be a cakewalk. Things did go pretty smoothly...but there was one little "gotcha" that took more time than the few seconds it really warranted. The Problem Every DBMS has its own way of automatically generating primary keys, and each has its pros and cons. For the Oracle Database, you use a sequence and point your Java classes to it using annotations that look something like this: @GeneratedValue(strategy=GenerationType.SEQUENCE, generator="POC_ID_SEQ") @SequenceGenerator(name="POC_ID_SEQ", sequenceName="POC_ID_SEQ", allocationSize=1) Between creating the actual sequence in the database and making sure you have your annotations right (watch those typos!), it seems a bit cumbersome. But it typically "just works", without fuss. Enter MySQL. Designating an integer-based field as PRIMARY KEY and using the keyword AUTO_INCREMENT makes the same task seem much simpler. And it is, mostly. But while NetBeans cranks out a superb "first cut" for a basic JSF CRUD app, there are a couple of small things you'll need to bring to the mix in order to be able to actually (C)reate records. The (RUD) performs fine out of the gate. The Solution Omitting all design considerations and activity (!), here is the basic sequence of events I followed to create, then resolve, the JSF/MySQL "Primary Key Perfect Storm": Fire up NetBeans. Create JSF project. Create Entity Classes from Database. Create JSF Pages from Entity Classes. Test run. Try to create record and hit error. It's a simple fix, but one that was fun to find in its completeness. :-) Even though you've told it what to do for a primary key, a MySQL table requires a gentle nudge to actually generate that new key value. Two things are needed to make the magic happen. First, you need to ensure the following annotation is in place in your Java entity classes: @GeneratedValue(strategy = GenerationType.IDENTITY) All well and good, but the real key is this: in your controller class(es), you'll have a create() function that looks something like this, minus the comment line and the setId() call in bold red type:     public String create() {         try {             // Assign 0 to ID for MySQL to properly auto_increment the primary key.             current.setId(0);             getFacade().create(current);             JsfUtil.addSuccessMessage(ResourceBundle.getBundle("/Bundle").getString("CategoryCreated"));             return prepareCreate();         } catch (Exception e) {             JsfUtil.addErrorMessage(e, ResourceBundle.getBundle("/Bundle").getString("PersistenceErrorOccured"));             return null;         }     } Setting the current object's primary key attribute to zero (0) prior to saving it tells MySQL to get the next available value and assign it to that record's key field. Short and simple…but not inherently obvious if you've never used that particular combination of NetBeans/JSF/MySQL before. Hope this helps! All the best, Mark

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  • What's the best version control/QA workflow for a legacy system?

    - by John Cromartie
    I am struggling to find a good balance with our development and testing process. We use Git right now, and I am convinced that ReinH's Git Workflow For Agile Teams is not just great for capital-A Agile, but for pretty much any team on DVCS. That's what I've tried to implement but it's just not catching. We have a large legacy system with a complex environment, hundreds of outstanding and undiscovered defects, and no real good way to set up a test environment with realistic data. It's also hard to release updates without disrupting users. Most of all, it's hard to do thorough QA with this process... and we need thorough testing with this legacy system. I feel like we can't really pull off anything as slick as the Git workflow outlined in the link. What's the way to do it?

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  • Webcast Series: Accelerate Business-Critical Database Deployments with Oracle Optimized Solutions

    - by ferhat
    Join us for this two-part Webcast series and learn how to safely consolidate business-critical databases and deliver quantifiable benefits to the business: Save up to 75% in operational and acquisition costs Save millions of dollars consolidating legacy infrastructure Leverage best practices from thousands of customer environments Increase end user productivity with 75% faster time to operations and 4x faster throughput   The Oracle Optimized Solution for Oracle Database  provides extensive guidelines for architecting and deploying complete database solutions that deliver superior performance and availability while minimizing cost and risk. Oracle’s world-class engineering teams work together to define these optimal architectures using Oracle's powerful SPARC M-Series and SPARC T-Series servers together with Oracle Solaris and Oracle's SAN, NAS, and flash-based storage to run the industry-leading Oracle Database. Quite simply, the Oracle Optimized Solution for Oracle Database makes it easier for you to deliver and manage business critical database environments that are fast, secure and cost-effective. Available On-Demand PART 1: Why Architecture Matters When Deploying Business-Critical Databases PART 2: How To Consolidate Databases Using Oracle Optimized Solutions   Presented by: Lawrence McIntosh, Principal Enterprise Architect, Oracle Optimized Solutions Ken Kutzer, Principal Product Manager, Infrastructure Solutions, Oracle  

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  • SQLPASS DB Design Precon Preview

    - by drsql
    It is just a few months left before SQLPASS and I am pushing to get my precon prepped for you. While it will be the second time I produce this on the year, I listened to the feedback and positive comments I have heard from potential attendees, so I am making a couple of big changes to fit what people really liked. Lots more design time. We will do more designs in some form, as a group, teams, and individually, depending on the room and people in attendance. (Figure on a lot of databases centered...(read more)

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  • Vendors: Partners or Salespeople?

    - by BuckWoody
    I got a great e-mail from a friend that asked about how he could foster a better relationship with his vendors. So many times when you work with a vendor it’s more of a used-car sales experience than a partnership – but you can actually make your vendor more of a partner, as long as you both set some ground-rules at the start. Sit down with your vendor, and have a heart-to-heart talk with them, explain that they won’t win every time, but that you’re willing to work with them in an honest way on both sides. Here’s the advice I sent him verbatim. I hope this post generates lots of comments from both customers and vendors. I don’t expect that you’ve had a great experience with your Microsoft reps, but I happen to work with some of the best sales teams in the business, and our clients tell us that all the time. “The key to this relationship is to keep the audience really small. Ideally there should be one person from your side that is responsible for the relationship, and one from the vendor’s side. Each responsible person should have the authority to make decisions, and to bring in other folks as needed for a given topic, project or decision.   For Microsoft, this is called an “Account Manager” – they aren’t technical, they aren’t sales. They “own” a relationship with a company. They learn what the company does, who does it, and how. They are responsible to understand what the challenges in your company are. While they don’t know the bits and bytes of everything we sell, they know what each thing does, and who to talk to about it. I get a call from an Account Manager every week that has pre-digested an issue at an organization and says to me: “I need you to set up an architectural meeting with their technical staff to get a better read on how we can help with problem X.” I do that and then report back to the Account Manager what we learned.  All through this process there’s the atmosphere of a “team”, not a “sales opportunity” per se. I’ve even recommended that the firm use a rival product, and I’ve never gotten push-back on that decision from my Account Managers.   But that brings up an interesting point. Someone pays an Account Manager and pays me. They expect something in return. At some point, you have to buy something. Not every time, not every situation – sometimes it’s just helping you with what you already bought from us. But the point is that you can’t expect lots of love and never spend any money. That’s the way business works.   Finally, don’t view the vendor as someone with their hand in your pocket – somebody that’s just trying to sell you something and doesn’t care if they ever see you again – unless they deserve it. There are plenty of “love them and leave them” companies out there, and you may have even had this experience with us, but that isn’t the case in the firms I work with. In fact, my customers get a questionnaire that asks them that exact question. “How many times have you seen your account team? Did you like your interaction with them? Can they do better?” My raises, performance reviews and general standing in my group are based on the answers the company gives.  Ask your vendor if they measure their sales and support teams this way – if not, seek another vendor to partner with.   Partnering with someone is a big deal. It involves time and effort on your part, and on the vendor’s part. If either of you isn’t pulling your weight, it just won’t work. You have every right to expect them to treat you as a partner, and they have the same right for your side.” Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

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  • Agile Testing Days 2012 – My First Conference!

    - by Chris George
    I’d like to give you a bit of background first… so please bear with me! In 1996, whilst studying for my final year of my degree, I applied for a job as a C++ Developer at a small software house in Hertfordshire  After bodging up the technical part of the interview I didn’t get the job, but was offered a position as a QA Engineer instead. The role sounded intriguing and the pay was pretty good so in the absence of anything else I took it. Here began my career in the world of software testing! Back then, testing/QA was often an afterthought, something that was bolted on to the development process and very much a second class citizen. Test automation was rare, and tools were basic or non-existent! The internet was just starting to take off, and whilst there might have been testing communities and resources, we were certainly not exposed to any of them. After 8 years I moved to another small company, and again didn’t find myself exposed to any of the changes that were happening in the industry. It wasn’t until I joined Red Gate in 2008 that my view of testing and software development as a whole started to expand. But it took a further 4 years for my view of testing to be totally blown open, and so the story really begins… In May 2012 I was fortunate to land the role of Head of Test Engineering. Soon after, I received an email with details for the “Agile Testi However, in my new role, I decided that it was time to bite the bullet and at least go to one conference. Perhaps I could get some new ideas to supplement and support some of the ideas I already had.ng Days” conference in Potsdam, Germany. I looked over the suggested programme and some of the talks peeked my interest. For numerous reasons I’d shied away from attending conferences in the past, one of the main ones being that I didn’t see much benefit in attending loads of talks when I could just read about stuff like that on the internet. So, on the 18th November 2012, myself and three other Red Gaters boarded a plane at Heathrow bound for Potsdam, Germany to attend Agile Testing Days 2012. Tutorial Day – “Software Testing Reloaded” We chose to do the tutorials on the 19th, I chose the one titled “Software Testing Reloaded – So you wanna actually DO something? We’ve got just the workshop for you. Now with even less powerpoint!”. With such a concise and serious title I just had to see what it was about! I nervously entered the room to be greeted by tables, chairs etc all over the place, not set out and frankly in one hell of a mess! There were a few people in there playing a game with dice. Okaaaay… this is going to be a long day! Actually the dice game was an exercise in deduction and simplification… I found it very interesting and is certainly something I’ll be using at work as a training exercise! (I won’t explain the game here cause I don’t want to let the cat out of the bag…) The tutorial consisted of several games, exploring different aspects of testing. They were all practical yet required a fair amount of thin king. Matt Heusser and Pete Walen were running the tutorial, and presented it in a very relaxed and light-hearted manner. It was really my first experience of working in small teams with testers from very different backgrounds, and it was really enjoyable. Matt & Pete were very approachable and offered advice where required whilst still making you work for the answers! One of the tasks was to devise several strategies for testing some electronic dice. The premise was that a Vegas casino wanted to use the dice to appeal to the twenty-somethings interested in tech, but needed assurance that they were as reliable and random as traditional dice. This was a very interesting and challenging exercise that forced us to challenge various assumptions, determine/clarify requirements but most of all it was frustrating because the dice made a very very irritating beeping noise. Multiple that by at least 12 dice and I was dreaming about them all that night!! Some of the main takeaways that were brilliantly demonstrated through the games were not to make assumptions, challenge requirements, and have fun testing! The tutorial lasted the whole day, but to be honest the day went very quickly! My introduction into the conference experience started very well indeed, and I would talk to both Matt and Pete several times during the 4 days. Days 1,2 & 3 will be coming soon…  

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  • Computer Networks UNISA - Chap 8 &ndash; Wireless Networking

    - by MarkPearl
    After reading this section you should be able to Explain how nodes exchange wireless signals Identify potential obstacles to successful transmission and their repercussions, such as interference and reflection Understand WLAN architecture Specify the characteristics of popular WLAN transmission methods including 802.11 a/b/g/n Install and configure wireless access points and their clients Describe wireless MAN and WAN technologies, including 802.16 and satellite communications The Wireless Spectrum All wireless signals are carried through the air by electromagnetic waves. The wireless spectrum is a continuum of the electromagnetic waves used for data and voice communication. The wireless spectrum falls between 9KHZ and 300 GHZ. Characteristics of Wireless Transmission Antennas Each type of wireless service requires an antenna specifically designed for that service. The service’s specification determine the antenna’s power output, frequency, and radiation pattern. A directional antenna issues wireless signals along a single direction. An omnidirectional antenna issues and receives wireless signals with equal strength and clarity in all directions The geographical area that an antenna or wireless system can reach is known as its range Signal Propagation LOS (line of sight) uses the least amount of energy and results in the reception of the clearest possible signal. When there is an obstacle in the way, the signal may… pass through the object or be obsrobed by the object or may be subject to reflection, diffraction or scattering. Reflection – waves encounter an object and bounces off it. Diffraction – signal splits into secondary waves when it encounters an obstruction Scattering – is the diffusion or the reflection in multiple different directions of a signal Signal Degradation Fading occurs as a signal hits various objects. Because of fading, the strength of the signal that reaches the receiver is lower than the transmitted signal strength. The further a signal moves from its source, the weaker it gets (this is called attenuation) Signals are also affected by noise – the electromagnetic interference) Interference can distort and weaken a wireless signal in the same way that noise distorts and weakens a wired signal. Frequency Ranges Older wireless devices used the 2.4 GHZ band to send and receive signals. This had 11 communication channels that are unlicensed. Newer wireless devices can also use the 5 GHZ band which has 24 unlicensed bands Narrowband, Broadband, and Spread Spectrum Signals Narrowband – a transmitter concentrates the signal energy at a single frequency or in a very small range of frequencies Broadband – uses a relatively wide band of the wireless spectrum and offers higher throughputs than narrowband technologies The use of multiple frequencies to transmit a signal is known as spread-spectrum technology. In other words a signal never stays continuously within one frequency range during its transmission. One specific implementation of spread spectrum is FHSS (frequency hoping spread spectrum). Another type is known as DSS (direct sequence spread spectrum) Fixed vs. Mobile Each type of wireless communication falls into one of two categories Fixed – the location of the transmitted and receiver do not move (results in energy saved because weaker signal strength is possible with directional antennas) Mobile – the location can change WLAN (Wireless LAN) Architecture There are two main types of arrangements Adhoc – data is sent directly between devices – good for small local devices Infrastructure mode – a wireless access point is placed centrally, that all devices connect with 802.11 WLANs The most popular wireless standards used on contemporary LANs are those developed by IEEE’s 802.11 committee. Over the years several distinct standards related to wireless networking have been released. Four of the best known standards are also referred to as Wi-Fi. They are…. 802.11b 802.11a 802.11g 802.11n These four standards share many characteristics. i.e. All 4 use half duplex signalling Follow the same access method Access Method 802.11 standards specify the use of CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) to access a shared medium. Using CSMA/CA before a station begins to send data on an 802.11 network, it checks for existing wireless transmissions. If the source node detects no transmission activity on the network, it waits a brief period of time and then sends its transmission. If the source does detect activity, it waits a brief period of time before checking again. The destination node receives the transmission and, after verifying its accuracy, issues an acknowledgement (ACT) packet to the source. If the source receives the ACK it assumes the transmission was successful, – if it does not receive an ACK it assumes the transmission failed and sends it again. Association Two types of scanning… Active – station transmits a special frame, known as a prove, on all available channels within its frequency range. When an access point finds the probe frame, it issues a probe response. Passive – wireless station listens on all channels within its frequency range for a special signal, known as a beacon frame, issued from an access point – the beacon frame contains information necessary to connect to the point. Re-association occurs when a mobile user moves out of one access point’s range and into the range of another. Frames Read page 378 – 381 about frames and specific 802.11 protocols Bluetooth Networks Sony Ericson originally invented the Bluetooth technology in the early 1990s. In 1998 other manufacturers joined Ericsson in the Special Interest Group (SIG) whose aim was to refine and standardize the technology. Bluetooth was designed to be used on small networks composed of personal communications devices. It has become popular wireless technology for communicating among cellular telephones, phone headsets, etc. Wireless WANs and Internet Access Refer to pages 396 – 402 of the textbook for details.

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  • Alkan Improves Aeronautical-Equipment Product Collaboration, Design Processes, and Government Compliance

    - by Gerald Fauteux
    Alkan S.A. a leading aeronautical equipment manufacturer in France, specializing in carriage-release and ejection systems for various types of military aircraft utilize Oracle’s AutoVue Electro-Mechanical Professional for Agile as part of its Agile Product Lifecycle Management solution. AutoVue Electro-Mechanical Professional for Agile enables multiformat 3-D viewing of engineering designs, leading to deeper analysis of component and product functionality and allows all teams to easily participate and contribute to product data early in the development cycle. Alkan S.A.’s equipment is used in more than 65 countries and is certified for more than 60 types of aircraft, worldwide. Click here to read the complete story. French version.

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  • Topeka Dot Net User Group (DNUG) Meeting &ndash; April 6, 2010

    Topeka DNUG is free for anyone to attend! Mark your calendars now! SPEAKER: Troy Tuttle is a self-described pragmatic agilist, and Kanban practitioner, with more than a decade of experience in delivering software in the finance and health industries and as a consultant. He advocates teams improve their performance through pursuit of better practices like continuous integration and automated testing. Troy is the founder of the Kansas City Limited WIP Society and is a speaker at local area groups...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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