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  • Unexpected advantage of Engineered Systems

    - by user12244672
    It's not surprising that Engineered Systems accelerate the debugging and resolution of customer issues. But what has surprised me is just how much faster issue resolution is with Engineered Systems such as SPARC SuperCluster. These are powerful, complex, systems used by customers wanting extreme database performance, app performance, and cost saving server consolidation. A SPARC SuperCluster consists or 2 or 4 powerful T4-4 compute nodes, 3 or 6 extreme performance Exadata Storage Cells, a ZFS Storage Appliance 7320 for general purpose storage, and ultra fast Infiniband switches.  Each with its own firmware. It runs Solaris 11, Solaris 10, 11gR2, LDoms virtualization, and Zones virtualization on the T4-4 compute nodes, a modified version of Solaris 11 in the ZFS Storage Appliance, a modified and highly tuned version of Oracle Linux running Exadata software on the Storage Cells, another Linux derivative in the Infiniband switches, etc. It has an Infiniband data network between the components, a 10Gb data network to the outside world, and a 1Gb management network. And customers can run whatever middleware and apps they want on it, clustered in whatever way they want. In one word, powerful.  In another, complex. The system is highly Engineered.  But it's designed to run general purpose applications. That is, the physical components, configuration, cabling, virtualization technologies, switches, firmware, Operating System versions, network protocols, tunables, etc. are all preset for optimum performance and robustness. That improves the customer experience as what the customer runs leverages our technical know-how and best practices and is what we've tested intensely within Oracle. It should also make debugging easier by fixing a large number of variables which would otherwise be in play if a customer or Systems Integrator had assembled such a complex system themselves from the constituent components.  For example, there's myriad network protocols which could be used with Infiniband.  Myriad ways the components could be interconnected, myriad tunable settings, etc. But what has really surprised me - and I've been working in this area for 15 years now - is just how much easier and faster Engineered Systems have made debugging and issue resolution. All those error opportunities for sub-optimal cabling, unusual network protocols, sub-optimal deployment of virtualization technologies, issues with 3rd party storage, issues with 3rd party multi-pathing products, etc., are simply taken out of the equation. All those error opportunities for making an issue unique to a particular set-up, the "why aren't we seeing this on any other system ?" type questions, the doubts, just go away when we or a customer discover an issue on an Engineered System. It enables a really honed response, getting to the root cause much, much faster than would otherwise be the case. Here's a couple of examples from the last month, one found in-house by my team, one found by a customer: Example 1: We found a node eviction issue running 11gR2 with Solaris 11 SRU 12 under extreme load on what we call our ExaLego test system (mimics an Exadata / SuperCluster 11gR2 Exadata Storage Cell set-up).  We quickly established that an enhancement in SRU12 enabled an 11gR2 process to query Infiniband's Subnet Manager, replacing a fallback mechanism it had used previously.  Under abnormally heavy load, the query could return results which were misinterpreted resulting in node eviction.  In several daily joint debugging sessions between the Solaris, Infiniband, and 11gR2 teams, the issue was fully root caused, evaluated, and a fix agreed upon.  That fix went back into all Solaris releases the following Monday.  From initial issue discovery to the fix being put back into all Solaris releases was just 10 days. Example 2: A customer reported sporadic performance degradation.  The reasons were unclear and the information sparse.  The SPARC SuperCluster Engineered Systems support teams which comprises both SPARC/Solaris and Database/Exadata experts worked to root cause the issue.  A number of contributing factors were discovered, including tunable parameters.  An intense collaborative investigation between the engineering teams identified the root cause to a CPU bound networking thread which was being starved of CPU cycles under extreme load.  Workarounds were identified.  Modifications have been put back into 11gR2 to alleviate the issue and a development project already underway within Solaris has been sped up to provide the final resolution on the Solaris side.  The fixed SPARC SuperCluster configuration greatly aided issue reproduction and dramatically sped up root cause analysis, allowing the correct workarounds and fixes to be identified, prioritized, and implemented.  The customer is now extremely happy with performance and robustness.  Since the configuration is common to other customers, the lessons learned are being proactively rolled out to other customers and incorporated into the installation procedures for future customers.  This effectively acts as a turbo-boost to performance and reliability for all SPARC SuperCluster customers.  If this had occurred in a "home grown" system of this complexity, I expect it would have taken at least 6 months to get to the bottom of the issue.  But because it was an Engineered System, known, understood, and qualified by both the Solaris and Database teams, we were able to collaborate closely to identify cause and effect and expedite a solution for the customer.  That is a key advantage of Engineered Systems which should not be underestimated.  Indeed, the initial issue mitigation on the Database side followed by final fix on the Solaris side, highlights the high degree of collaboration and excellent teamwork between the Oracle engineering teams.  It's a compelling advantage of the integrated Oracle Red Stack in general and Engineered Systems in particular.

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  • How does session middleware generally verify browser sessions?

    - by BBnyc
    I've been using session middleware to build web apps for years: from PHP's built-in session handling layer to node's connect session middleware. However, I've never tried (or needed) to roll my own session handling layer. How would one go about it? What sort of checks are necessary to provide at least some modicum of security against HTTP session highjacking? I figure setting a cookie with a token to keep track of the session, and then perhaps some check to see that the originating IP address of the session doesn't change and that the client browser software remains consistent. Hoping to hear about current best-practices...

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  • Moving DataSets through BizTalk

    - by EltonStoneman
    [Source: http://geekswithblogs.net/EltonStoneman] Yuck. But sometimes you have to, so here are a couple of things to bear in mind: Schemas Point a codegen tool at a WCF endpoint which exposes a DataSet and it will generate an XSD which describes the DataSet like this: <xs:elementminOccurs="0"name="GetDataSetResult"nillable="true">  <xs:complexType>     <xs:annotation>       <xs:appinfo>         <ActualTypeName="DataSet"                     Namespace="http://schemas.datacontract.org/2004/07/System.Data"                     xmlns="http://schemas.microsoft.com/2003/10/Serialization/" />       </xs:appinfo>     </xs:annotation>     <xs:sequence>       <xs:elementref="xs:schema" />       <xs:any />     </xs:sequence>  </xs:complexType> </xs:element>  In a serialized instance, the element of type xs:schema contains a full schema which describes the structure of the DataSet – tables, columns etc. The second element, of type xs:any, contains the actual content of the DataSet, expressed as DiffGrams: <GetDataSetResult>  <xs:schemaid="NewDataSet"xmlns:xs="http://www.w3.org/2001/XMLSchema"xmlns=""xmlns:msdata="urn:schemas-microsoft-com:xml-msdata">     <xs:elementname="NewDataSet"msdata:IsDataSet="true"msdata:UseCurrentLocale="true">       <xs:complexType>         <xs:choiceminOccurs="0"maxOccurs="unbounded">           <xs:elementname="Table1">             <xs:complexType>               <xs:sequence>                 <xs:elementname="Id"type="xs:string"minOccurs="0" />                 <xs:elementname="Name"type="xs:string"minOccurs="0" />                 <xs:elementname="Date"type="xs:string"minOccurs="0" />               </xs:sequence>             </xs:complexType>           </xs:element>         </xs:choice>       </xs:complexType>     </xs:element>  </xs:schema>  <diffgr:diffgramxmlns:diffgr="urn:schemas-microsoft-com:xml-diffgram-v1"xmlns:msdata="urn:schemas-microsoft-com:xml-msdata">     <NewDataSetxmlns="">       <Table1diffgr:id="Table11"msdata:rowOrder="0"diffgr:hasChanges="inserted">         <Id>377fdf8d-cfd1-4975-a167-2ddb41265def</Id>         <Name>157bc287-f09b-435f-a81f-2a3b23aff8c4</Name>         <Date>a5d78d83-6c9a-46ca-8277-f2be8d4658bf</Date>       </Table1>     </NewDataSet>  </diffgr:diffgram> </GetDataSetResult> Put the XSD into a BizTalk schema and it will fail to compile, giving you error: The 'http://www.w3.org/2001/XMLSchema:schema' element is not declared. You should be able to work around that, but I've had no luck in BizTalk Server 2006 R2 – instead you can safely change that xs:schema element to be another xs:any type: <xs:elementminOccurs="0"name="GetDataSetResult"nillable="true">  <xs:complexType>     <xs:sequence>       <xs:any />       <xs:any />     </xs:sequence>  </xs:complexType> </xs:element>  (This snippet omits the annotation, but you can leave it in the schema). For an XML instance to pass validation through the schema, you'll also need to flag the any attributes so they can contain any namespace and skip validation:  <xs:elementminOccurs="0"name="GetDataSetResult"nillable="true">  <xs:complexType>     <xs:sequence>       <xs:anynamespace="##any"processContents="skip" />       <xs:anynamespace="##any"processContents="skip" />     </xs:sequence>  </xs:complexType> </xs:element>  You should now have a compiling schema which can be successfully tested against a serialised DataSet. Transforms If you're mapping a DataSet element between schemas, you'll need to use the Mass Copy Functoid to populate the target node from the contents of both the xs:any type elements on the source node: This should give you a compiled map which you can test against a serialized instance. And if you have a .NET consumer on the other side of the mapped BizTalk output, it will correctly deserialize the response into a DataSet.

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  • Order independent transparency in particle system

    - by Stepan Zastupov
    I'm writing a particle system and would like to find a trick to achieve proper alpha blending without sorting particles because: Each particle is a point sprite in a single mesh and I can't use scene graph ability to sort transparent nodes. The system node should be properly sorted, though. Particle position is computed on shader from initial velocity, acceleration and time. In order to sort the system I would have to perform all this computations on CPU, which is something I want to avoid. Sorting hundreds of particles against camera position and uploading it on GPU each frame seams to be quiet heavy operation. Alpha testing seems to be fast enough on GLES 2.0 and works fine for non-transparent but "masked" textures. Still, it's not enough for semi-transparent particles. How would you handle this?

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  • GTK applications do not start

    - by Greg
    Hello, I have a fresh install of Ubuntu 10.04 Server on nodes of a computational cluster, and I access the nodes via ssh. I configured a X server, which I start with the command startx -- -ac. The server is running fine on port :0. Then, I set the environment variable DISPLAY to :0. Now, when I run a GTK application on the node, it fails with the following error: Error: Unable to initialize gtk, is DISPLAY set properly? Now, my question is, is there any runtime library that I need for running GTK applications on top of a X server? I'm probably missing something obvious here, but I can't tell what :P

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  • Stumbling Through: Visual Studio 2010 (Part II)

    I would now like to expand a little on what I stumbled through in part I of my Visual Studio 2010 post and touch on a few other features of VS 2010.  Specifically, I want to generate some code based off of an Entity Framework model and tie it up to an actual data source.  Im not going to take the easy way and tie to a SQL Server data source, though, I will tie it to an XML data file instead.  Why?  Well, why not?  This is purely for learning, there are probably much better ways to get strongly-typed classes around XML but it will force us to go down a path less travelled and maybe learn a few things along the way.  Once we get this XML data and the means to interact with it, I will revisit data binding to this data in a WPF form and see if I cant get reading, adding, deleting, and updating working smoothly with minimal code.  To begin, I will use what was learned in the first part of this blog topic and draw out a data model for the MFL (My Football League) - I dont want the NFL to come down and sue me for using their name in this totally football-related article.  The data model looks as follows, with Teams having Players, and Players having a position and statistics for each season they played: Note that when making the associations between these entities, I was given the option to create the foreign key but I only chose to select this option for the association between Player and Position.  The reason for this is that I am picturing the XML that will contain this data to look somewhat like this: <MFL> <Position/> <Position/> <Position/> <Team>     <Player>         <Statistic/>     </Player> </Team> </MFL> Statistic will be under its associated Player node, and Player will be under its associated Team node no need to have an Id to reference it if we know it will always fall under its parent.  Position, however, is more of a lookup value that will not have any hierarchical relationship to the player.  In fact, the Position data itself may be in a completely different xml file (something Id like to play around with), so in any case, a player will need to reference the position by its Id. So now that we have a simple data model laid out, I would like to generate two things based on it:  A class for each entity with properties corresponding to each entity property An IO class with methods to get data for each entity, either all instances, by Id or by parent. Now my experience with code generation in the past has consisted of writing up little apps that use the code dom directly to regenerate code on demand (or using tools like CodeSmith).  Surely, there has got to be a more fun way to do this given that we are using the Entity Framework which already has built-in code generation for SQL Server support.  Lets start with that built-in stuff to give us a base to work off of.  Right click anywhere in the canvas of our model and select Add Code Generation Item: So just adding that code item seemed to do quite a bit towards what I was intending: It apparently generated a class for each entity, but also a whole ton more.  I mean a TON more.  Way too much complicated code was generated now that code is likely to be a black box anyway so it shouldnt matter, but we need to understand how to make this work the way we want it to work, so lets get ready to do some stumbling through that text template (tt) file. When I open the .tt file that was generated, right off the bat I realize there is going to be trouble there is no color coding, no intellisense no nothing!  That is going to make stumbling through more like groping blindly in the dark while handcuffed and hopping on one foot, which was one of the alternate titles I was considering for this blog.  Thankfully, the community comes to my rescue and I wont have to cast my mind back to the glory days of coding in VI (look it up, kids).  Using the Extension Manager (Available under the Tools menu), I did a quick search for tt editor in the Online Gallery and quickly found the Tangible T4 Editor: Downloading and installing this was a breeze, and after doing so I got some color coding and intellisense while editing the tt files.  If you will be doing any customizing of tt files, I highly recommend installing this extension.  Next, well see if that is enough help for us to tweak that tt file to do the kind of code generation that we wantDid 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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  • What is the name of this tree?

    - by Daniel
    It has a single root and each node has 0..N ordered sub-nodes . The keys represent a distinct set of paths. Two trees can only be merged if they share a common root. It needs to support, at minimum: insert, merge, enumerate paths. For this tree: The +-------+----------------+ | | | cat cow dog + +--------+ + | | | | drinks jumps moos barks + | milk the paths would be: The cat drinks milk The cow jumps The cow moos The dog barks It's a bit like a trie. What is it?

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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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  • Why does sound stop working after a while?

    - by badp
    I don't know how to reproduce this problem, because I don't regularly play music or sound. All I know is that, sometimes, I'll load a video (from youtube or from a local file) and there will be no sound. Everything looks fine software wise: Rebooting always fixes. aplay, paplay and pals give no error message I'm not in the audio group, as advised The device exists and appears in use: $ lsof /dev/snd/by-path/pci-0000\:00\:1b.0 COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME pulseaudi 17313 badp 23u CHR 116,10 0t0 7628 /dev/snd/by-path/../controlC0 pulseaudi 17313 badp 30u CHR 116,10 0t0 7628 /dev/snd/by-path/../controlC0 Restarting pulseaudio or alsa seems to do no good. What is wrong here?

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  • Basic game architechture best practices in Cocos2D on iOS

    - by MrDatabase
    Consider the following simple game: 20 squares floating around an iPhone's screen. Tapping a square causes that square to disappear. What's the "best practices" way to set this up in Cocos2D? Here's my plan so far: One Objective-c GameState singleton class (maintains list of active squares) One CCScene (since there's no menus etc) One CCLayer (child node of the scene) Many CCSprite nodes (one for each square, all child nodes of the layer) Each sprite listens for a tap on itself. Receive tap = remove from GameState Since I'm relatively new to Cocos2D I'd like some feedback on this design. For example I'm unsure of the GameState singleton. Perhaps it's unnecessary.

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  • Why should I use Bower? [closed]

    - by Wil
    I can fully appreciate the benefits of a package manager like Python PIP, Node npm, or Ruby Gems since they're doing much more than adding files to your applications path. Maybe I'm missing the point, or I'm being obtuse, but here are the negatives I can see: Separate step when building a project Separate dependency to install via another package manager (yo dawg) More clutter in the projects root with bower.json and / or .bowerrc Reliance on the registry being up to date, correct, and available Some imports / references to things like images won't work The positives I can see are these: I don't have to download the dependencies manually Optionally install packages as part of scaffolding based on user prompts or the like I'd really like to know of any benefits I'm unaware of, and I should say I'm not trying to be provocative I genuinely want to know.

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  • Getting into C# and MVC4 coming from Javascript

    - by Stefan V.
    Let me know if this is the wrong place to ask this but, I am trying to get into a backend/server language coming from a front-end javascript background (vanilla, angular, jQuery and a bit of node and mongodb, also some experience with PHP and MySQL). Why C#? My company's entire server-side is MVC4. Occasionally, I am going through commits of the backend guys and have asked them all sorts of questions. A lot of what I have heard and seen just seems appealing. Anyway, I'd rather start with C# first and gradually adopt .NET MVC. Does anybody advice, tips, recommended books, etc for somebody trying to learn C# coming from a JS background?

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  • How important is using the same language for client and server?

    - by Makita
    I have been evaluating architecture solutions for a mobile project that will have a web-service/app in addition to native apps and have been looking at various libraries, frameworks, and stacks like Meteor, this being a sort of "open stack package framework", is tightly bound with Node.js. There is a lot of talk about the benefits of using the same language both client and server side, and I'm not getting it. I could understand if you want to mirror the entire state of a web application on both client and server but struggling to find other wins... Workflow efficiency? I'm trying to understand why client/server language parity is considered to be a holy grail. Why does client/server language parity matter in software development?

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  • Custom graph comparison?

    - by user57828
    I'm trying to compare two graphs using hash value ( i.e, at the time of comparison, try to avoid traversing the graph ) Is there a way to make a function such that the hash values compared can also lead to determining at which height the graphs differ? The comparisons between two graphs are to be made by comparing children at a certain level. One way to compare the graphs is have a final hash value for the root node and compare them, but that wouldn't directly reflect at which level the graphs differ, since their immediate children might be the same ( or any other case ).

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  • How should I interpret these DirectX Caps Viewer values?

    - by tobi
    Briefly asking - what do the nodes mean and what the difference is between them in DirectX Caps Viewer? DXGI Devices Direct3D9 Devices DirectDraw Devices The most interesting for me is 1 vs 2. In the Direct3D9 Devices under HAL node I can see that my GeForce 8800GT supports PixelShaderVersion 3.0. However, under DXGI Devices I have DX 10, DX 10.1 and DX 11 having Shader model 4.0 (actually why DX 11? My card is not compatible with DX 11). I am implementing a DX 11 application (including d3d11.h) with shaders compiled in 4.0 version, so I can clearly see that 4.0 is supported. What is the difference between 1 and 2? Could you give me some theory behind the nodes?

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  • Cocos2d: Moving background on update: offsett issue

    - by mm24
    working with Objective C, iOS and Cocos2d I am developing a vertical scrolling shooter game for iPhone (retina display models with 640 width x 960 height pixel resolution). My basic algorithm works as following: I create two instances of an image that has exactly 640 width x 960 height pixel of resolution, which we will call imageA and imageB I then set the two imags with exactly 480.0f of offset from each other, as the screenSize of a CCScene is set by default to 480.0f. At each update method call I move the two images by the same value. I make sure that their offsett stays to 480.0f However when running the game I see a 1 pixel height line between the two images. This literally bugs me and would like to adjust this. What am I doing wrong? This is a zoom in on the background when the "offsett line" is visible. The white line you can see divides the two background images and is not meant to exist as both images are completely black :): If I change the yPositionOfSecondElement value to 479.0f until the first loop the two images overlap correctly, but as soon as the loop starts the two images starts having an offsett of -1.0f. Here is the initialization code: -(void) init { //... screenHeight = 480.0f; yPositionOfSecondElement= screenHeight;//I tried subtracting an offsett of -1 but eventually the image would go wrong again yPositionOfFirstElement = 0.0f; loopedBackgroundImageInstanceA = [BackgroundLoopedImage loopImageForLevel:levelName]; loopedBackgroundImageInstanceA.anchorPoint = CGPointMake(0.5f, 0.0f); loopedBackgroundImageInstanceA.position = CGPointMake(160.0f, yPositionOfFirstElement); [node addChild:loopedBackgroundImageInstanceA z:zLevelBackground]; //loopedBackgroundImageInstanceA.color= ccRED; loopedBackgroundImageInstanceB = [BackgroundLoopedImage loopImageForLevel:levelName]; loopedBackgroundImageInstanceB.anchorPoint = CGPointMake(0.5f, 0.0f); loopedBackgroundImageInstanceB.position = CGPointMake(160.0f, yPositionOfSecondElement); [node addChild:loopedBackgroundImageInstanceB z:zLevelBackground]; //.... } And here is the move code called at each update: -(void) moveBackgroundSprites:(BackgroundLoopedImage*)imageA :(BackgroundLoopedImage*)imageB :(ccTime)delta { isEligibleToMove=false; //This is done to avoid rounding errors float yStep = delta * [GameController sharedGameController].currentBackgroundSpeed; NSString* formattedNumber = [NSString stringWithFormat:@"%.02f", yStep]; yStep = atof([formattedNumber UTF8String]); //First should adjust position of images [self adjustPosition:imageA :imageB]; //The can get the actual image position CGPoint posA = imageA.position; CGPoint posB = imageB.position; //Here could verify if the checksum is equal to the required difference (should be 479.0f) if (![self verifyCheckSum:posA :posB]) { CCLOG(@"does not comply A"); } //At this stage can compute the hypotetical new position CGPoint newPosA = CGPointMake(posA.x, posA.y - yStep); CGPoint newPosB = CGPointMake(posB.x, posB.y - yStep); // Reposition stripes when they're out of bounds if (newPosA.y <= -yPositionOfSecondElement) { newPosA.y = yPositionOfSecondElement; [imageA shuffle]; if (timeElapsed>=endTime && hasReachedEndLevel==FALSE) { hasReachedEndLevel=TRUE; shouldMoveImageEnd=TRUE; } } else if (newPosB.y <= -yPositionOfSecondElement) { newPosB.y = yPositionOfSecondElement; [imageB shuffle]; if (timeElapsed>=endTime && hasReachedEndLevel==FALSE) { hasReachedEndLevel=TRUE; shouldMoveImageEnd=TRUE; } } //Here should verify that the check sum is equal to 479.0f if (![self verifyCheckSum:posA :posB]) { CCLOG(@"does not comply B"); } imageA.position = newPosA; imageB.position = newPosB; //Here could verify that the check sum is equal to 479.0f if (![self verifyCheckSum:posA :posB]) { CCLOG(@"does not comply C"); } isEligibleToMove=true; } -(BOOL) verifyCheckSum:(CGPoint)posA :(CGPoint)posB { BOOL comply = false; float sum = 0.0f; if (posA.y > posB.y) { sum = posA.y - posB.y; } else if (posB.y > posA.y){ sum = posB.y - posA.y; } else{ return false; } if (sum!=yPositionOfSecondElement) { comply= false; } else{ comply=true; } return comply; } And here is what happens on the update: if(shouldMoveImageA && shouldMoveImageB) { if (isEligibleToMove) { [self moveBackgroundSprites:loopedBackgroundImageInstanceA :loopedBackgroundImageInstanceB :delta]; } Forget about shouldMoveImageA and shouldMoveImageB, this is just for when the background reaches the end of level, this works.

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  • MAAS fails to Commission nodes

    - by user3644848
    I'm evaluating MaaS/Juju. I followed instructions in this link http://maas.ubuntu.com/docs1.5/install.html to setup MaaS. I'm running this in Oracle VirtualBox environment so Power options are not configured for the VMs. PXE booting VM works fine. The node shuts down itself and registers with MaaS in Declared state. Issues: a) When I Commission the VM (which is in the Declared state), first it gets IP-Config: no response after 60 secs - giving up errors. (See link below for a screenshot). b) Fails to mount the boot device and drops into initramfs prompt. I've copied logs here: https://www.dropbox.com/sh/5gy9nnonbnccufo/AAD9o4awSOtyaCCmRe5q7rBva Any help to get past this is greatly appreciated. Thanks!

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  • Humor in Documentation

    - by Lex Fridman
    Is a small amount of lighthearted wording or humor acceptable in source code documentation? For example, I have an algorithm that has a message hop around a graph (network) until its path forms a cycle. When this happens it is removed from the queue of the node it last resided on which removes it from memory. I write that in a comment, and finish the comment with "Rest in peace, little guy". That serves very little documenting purpose, but it cheers me up a bit, and I imagine it might cheer up other people I'm working with as they read through the code. Is this an acceptable practice, or should my in-code documentation resemble as much as possible the speeches of 2004 presidential candidate John Kerry? ;-)

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  • How to make bash script run with a latency (i.e. wait 1 sec at each iterations)?

    - by user2413
    I have this bash script; for (( i = 1 ; i <= 160 ; i++ )); do qsub myccomputations"${i}".pbs done Basically, I would prefer if there was a 1 second delay between each iteration. The reason is that at each iterations, it sends the program file mycomputation"${i}$.pbs to a core node for solving. Solving in this instance involves the use of pseudo random numbers. I suspect the RNG I use (R's) uses CPU time as seed because as things are now I get repeating pseudo random numbers (at the rate of approx 1 out of 100). So how to you ask bash to for (( i = 1 ; i <= 160 ; i++ )); do wait 1 sec qsub myccomputations"${i}".pbs done

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  • errors with libosmscout [migrated]

    - by Katlego Moukangwe
    I am using the libosmscout library for routing and I get the following error when I run the Routing demo; Routing . 169639811 169639816 169639831 253045594 //Running the routing demo with the map in the current directory. Cannot get start way! There was an error while calculating the route! I think It might be during the import stage since I get the following warnings; !! Cannot resolve way member 28693141 for relation 28322 boundary_administrative Mecklenburg-Vorpommern !! Cannot resolve way member 152675051 for relation 28936 boundary_administrative Bergedorf !! Cannot resolve way member 26496646 for relation 28964 boundary_administrative Harburg (Hamburg) !! Node 323985058 of way 135078286 cannot be joined with any other way of the relation 1817154 Neuenkirchen WW Multipolygon relation 2136137 has conflicting types for outer boundary (place_island vs. boundary_administrative) !! Cannot resolve way member 162656856 for relation 2174826 landuse_forest

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  • Collision detection in multiplayer games

    - by Bane
    This a followup to my previous question: How to implement physics and AoE spells in an MMO game?. There, we concluded that all physics have to be done on the server, and that I should use cylinders for calculations. Now, how can I check for collision detection on a ground-to-player basis on the server? It's fairly easy if the ground is a flat space, I just check if the player's z coordinate is lower than some value and voila, but, what if the map/ground itself is a model? How do I know where hills are on the server-side? How do I know when object collisions happen? I'm using node.js and socket.io.

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  • Design a Distributed System

    - by Bonton255
    I am preparing for an interview on Distributed Systems. I have gone through a lot of text and understand the basics of the area. However, I need some examples of discussions on designing a distributed system given a scenario. For example, if I were to design a distributed system to calculate if a number N is primary or not, what will the be design of the system, what will be the impact of network latency, CPU performance, node failure, addition of nodes, time synchronization etc. If you guys could present your in-depth thoughts on this example, or point me to some similar discussion, that would be really helpful.

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  • ssis 2012 timeouts

    - by Alex Bransky
    Originally posted on: http://geekswithblogs.net/influent1/archive/2014/05/30/156699.aspxI started getting timeouts from SSIS 2012 using the SSISDB and I couldn't make any sense of them, they seemed random.  When things were bad I couldn't even expand the Integration Services Catalogs node in SSMS.  Just by sheer luck I figured out the problem: too much data was being logged in SSISDB and the data file was up to 180 GB, with the log file at 500 GB.  I switched it to simple mode and shrank the log file, then changed the retention period to 90 days instead of 365.  Now I need to see what else I can do to keep it running smoothly...Note this:  http://www.ssistalk.com/2012/07/16/ssis-2012-beware-the-ssis-server-maintenance-job/

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  • All around design book for a developer (Javascript dev)

    - by Alex Angelini
    I have begun doing a lot of javascript development recently, mostly front-end but also using node.js. As I am currently in the transition from large company to startup, they expect me as a front end developer to know how to produce semi decent designs (Which I cannot) I am looking for a book (or set of screencasts) to give me some good well rounded advice on design. I know CSS, but my design are always awful looking, I also know nothing about Photoshop (and am on Linux and have no access to it) What are your picks? I am not looking to be a full time designer I would just like to be able to contribute.

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  • Queuing rpc calls

    - by alfa64
    i'm designing a system wich listen to json rpc calls from clients, piles it up inside a list, and if it gets full it should store them in a DB and keep recieving calls. My original plan is to listen to the rpc calls from Perl with the json-rpc and put them in the array. The clients do some long polling in another server to get responses as they appear. What is this blocking/noblocking thing? Should i do a script for node.js to listen to the calls? What do you think is a good practice in this case? The objective is to listen as much calls as possible.

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