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  • Update from Ola Hallengren: Target multiple devices during SQL Server backup

    - by Greg Low
    Ola has produced another update of his database management scripts. If you haven't taken a look at them, you should. At the very least, they'll give you good ideas about what to implement and how others have done so. The latest update allows targeting multiple devices during backup. This is available in native SQL Server backup and can be helpful with very large databases. Ola's scripts now support it as well.Details are here: http://ola.hallengren.com/sql-server-backup.html http://ola.hallengren.com/versions.html The following example shows it backing up to 4 files on 4 drives, one file on each drive:EXECUTE dbo.DatabaseBackup@Databases = 'USER_DATABASES',@Directory = 'C:\Backup, D:\Backup, E:\Backup, F:\Backup',@BackupType = 'FULL',@Compress = 'Y',@NumberOfFiles = 4And this example shows backing up to 16 files on 4 drives, 4 files on each drive: EXECUTE dbo.DatabaseBackup@Databases = 'USER_DATABASES',@Directory = 'C:\Backup, D:\Backup, E:\Backup, F:\Backup',@BackupType = 'FULL',@Compress = 'Y',@NumberOfFiles = 16Ola mentioned that you can now back up to up to 64 drives. 

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  • Embed Unity3D and load multiple games from a single app

    - by Rafael Steil
    Is is possible to export an entire unity3d project/game as an AssetBundle and load it on iOS/Android/Windows on an app that doesn't know anything about such game beforehand? What I have in mind is something like the web plugin does - it loads a series of .unity3d files over http, and render inline in the browser window. Is it even possible to do something closer for iOS/Android? I have read a lot of docs so far, but still can't be sure: http://floored.com/blog/2013/integrating-unity3d-within-ios-native-application.html http://docs.unity3d.com/Manual/LoadingResourcesatRuntime.html http://docs.unity3d.com/Manual/AssetBundlesIntro.html The code from the post at http://forum.unity3d.com/threads/112703-Override-Unity-Data-folder-path?p=749108&viewfull=1#post749108 works for Android, but how about iOS and other platforms?

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  • adjust resolution on Ubuntu Server 10.04?

    - by Mike Grace
    Installed Ubuntu Server 10.04 on an old laptop and I noticed that the system is trying to show the CLI below my screen. This means that if I run a script or a program with a bunch of output, once it is done, I have to press return several times to bring the output to the point where I can actually see it on the screen. I also have to clear the screen to be able to see what I am typing at the current command prompt. The laptop is an EliteGroup 536S with a native screen resolution of 1024 x 768 How can I adjust the resolution for Ubuntu Server 10.04? What file do I need to edit if editing a file is the solution? I've seen posts on how to change the resolution on the desktop version of Ubuntu but not the server version.

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  • Develop 3d game for iphone & android in single code

    - by lajpat
    I have to make a 3d game on the lines of this app 3D Chess I want to make this app for both android & iphone by writing a single code. Of course little native code will be required to be done. I want to ensure that entire logic & animation code is written only once. What software does one suggest to achieve this since I am not a tight schedule. I came across Corona but I am not sure if such game can be made using it. Others I found Unity & Shiva. I am not experience in 3D game so please if someone can help Thanks Lajpat

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  • What is the advantage of a programmers VM apart from portability

    - by user619818
    I can understand the benefits of Java running on a JVM. Portability. Nice simple reason. But I have always been puzzled as to why Microsoft brought out their own version of a JVM - .NET. C# is supposed to be a fine language (haven't used myself) but could Microsoft have launched product to use native. ie to generate an exe? My colleague is learning F#. The reason it has to be a language which runs on .NET is because the Microsoft Lync API which will be used is only available on .NET. ie there is no C API for Lync. A cynical view may be that the reason is vendor lockin. F# will only run on a Microsoft platform (or C# for that matter) and so program is locked in. But maybe I am missing some other benefit of a VM platform?

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  • How do I store the OAuth v1 consumer key and secret for an open source desktop Twitter client without revealing it to the user?

    - by Justin Dearing
    I want to make a thick-client, desktop, open source twitter client. I happen to be using .NET as my language and Twitterizer as my OAuth/Twitter wrapper, and my app will likely be released as open source. To get an OAuth token, four pieces of information are required: Access Token (twitter user name) Access Secret (twitter password) Consumer Key Consumer Secret The second two pieces of information are not to be shared, like a PGP private key. However, due to the way the OAuth authorization flow is designed, these need to be on the native app. Even if the application was not open source, and the consumer key/secret were encrypted, a reasonably skilled user could gain access to the consumer key/secret pair. So my question is, how do I get around this problem? What is the proper strategy for a desktop Twitter client to protect its consumer key and secret?

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  • Converting ANTLR AST to Java bytecode using ASM

    - by Nick
    I am currently trying to write my own compiler, targeting the JVM. I have completed the parsing step using Java classes generated by ANTLR, and have an AST of the source code to work from (An ANTLR "CommonTree", specifically). I am using ASM to simplify the generating of the bytecode. Could anyone give a broad overview of how to convert this AST to bytecode? My current strategy is to explore down the tree, generating different code depending on the current node (using "Tree.getType()"). The problem is that I can only recognise tokens from my lexer this way, rather than more complex patterns from the parser. Is there something I am missing, or am I simply approaching this wrong? Thanks in advance :)

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  • Multi-platform Map Application

    - by Mahdi
    I'm working on a web project (PHP, jQuery) which currently using Google Maps powering up the map functionality of the application, however we need to make it multi-platform like you can go to the dashboard and choose one from 5-10 map providers (which Goolge Maps is just one of them) to underlying your map functionality. So, as the application is supposed to show the data on map, almost in every single place we have to deal with the API provided by that specific map provider. Currently we are thinking about revising our modular structure and/or making something like an adapter for each provider to deal with their native syntax but via our standard methods. I wish to have your ideas and your experiences, specially if you ever made an interface for dealing via 2-3 different map providers. That would helps much and I really appreciate that. If you need any further information, just ask me to update the question. Update: As Vicky Chijwani suggested Mapstraction, now I'm also wondering which one is more better (pros & cons), having an adapter implemented on Javascript or PHP?

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  • How can I play AMR files in Firefox on Ubuntu?

    - by Dave M G
    I use Evernote to keep voice and text notes. Unfortunately, I've just discovered that I can't take full advantage of the cloud storage capabilities of Evernote, because support for Android's native sound file format, AMR, is deficient in Ubuntu. When I view my voice notes in Firefox in Ubuntu, I get a "missing plugin" error. The problem is discussed on the Evernote forums, but the solutions offered there are really lacking. They all involve saving and converting files, which seems like an unreasonable amount of fiddling. Surely an AMR file is just a sound file, and surely Ubuntu could (and should) have a way of playing it? There is some suggestion that Media Player can play AMR format, and I thought there was a Media Player plugin for Firefox. But I can not find any specifics. How can I get Ubuntu to play AMR file directly in Firefox in Ubuntu?

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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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  • 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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  • 7-minute Community GlassFish Clustering Screencast

    - by alexismp
    Community member Faissal has recently put up a 7-minute screencast of an un-edited setup of a GlassFish cluster. His clustering setup spans across a mac and a virtualized Ubuntu host. It can probably be further simplified using the SSH provisioning feature (asadmin install-node) to avoid logging into remote machines. You may remember John's GlassFish clustering in under 10 minutes, a very successful video which was based on version 2. Since that we've put out a number of demos on YouTube for our 3.1.x versions including a full webinar replay.

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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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  • Coming Soon! Oracle Global Trade Management Solutions

    An exciting new solution offering, Oracle Global Trade Management helps companies manage the Has the complexity of worldwide trade compliance while also mitigating compliance risk and uncovering supply chain inefficiencies. Oracle Global Trade Management helps organizations lower operational costs and improve network efficiencies by created barriers and roadblocks in your business processes? Do you seek ways to mitigate compliance risk while at the same time find hidden cash in your supply chain? If these issues affect your company, tune in to hear how the new Oracle Global Trade Management solution automatinges and streamlininges cross-border transactions. as part of the Value Chain Execution suite and a native trade and transportation platform.

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  • How to composite videos and make animations in Ubuntu?

    - by Naveen
    Well, I'm not talking about programs like NukeX, Cinelerra, Jahshaka because they aren't either free or feature rich. I have seen couple of cool videos done on Linux platform, most likely to be Ubuntu. How Linux is Built - Linux Foundation Ubuntu 12.10 Beta Overview - OMG! Ubuntu What is the magic application they are using to composit those videos..? Can upcoming LightWorks workout these effects...? Is there any Linux native OpenGL based application to deal with particles, just like Particle Illusion for Windows? Thanks!

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  • Traktor Audio 2 DJ soundcard configuration

    - by Jaroslav
    I have a Traktor Audio 2 DJ USB sound card (the first version of what it's now called simply Traktor Audio 2) The problem in settings it only sees one output, when there should be two (I need that for Mixxx etc.) Also I want to be able set the sample rate to one of these: 44.1, 48, 88.2, 96 kHz or at least check which one is set. Additionally if possible setting the latency would be an advantage. Some info: $ aplay -l **** List of PLAYBACK Hardware Devices **** card 0: HDMI [HDA ATI HDMI], device 3: HDMI 0 [HDMI 0] Subdevices: 1/1 Subdevice #0: subdevice #0 card 1: TraktorAudio2 [Traktor Audio 2], device 0: Traktor Audio 2 [Traktor Audio 2] Subdevices: 1/2 Subdevice #0: subdevice #0 Subdevice #1: subdevice #1 $ cat /proc/asound/cards 0 [HDMI ]: HDA-Intel - HDA ATI HDMI HDA ATI HDMI at 0xfdcfc000 irq 45 1 [TraktorAudio2 ]: snd-usb-caiaq - Traktor Audio 2 Native Instruments Traktor Audio 2 (usb-0000:00:1d.7-8)

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  • IS it ok to use REST for CRUD operations?

    - by l0l0l0l0l
    Recently I moved to Laravel and I was surprised on how good setting the controllers as RESTful is, it made routes and my code cleaner. I'm kinda new on web development and never used REST before since all my clients' projects are basically CRUD operations. Are there any cool buzzword to this "approach" or I'm just stupid for doing it? I don't plan to follow any REST patterns, just to make my life easier and code cleaner. Basically just GET/POST, the other ones are not native anyway so (emulated on hidden form value).

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  • Save Windows 8 Files and Install Ubuntu

    - by Nika
    I would like to install Ubuntu on my laptop. I am new to Ubuntu and therefore have some questions: 1.My hardware is Acer Emachines Intel Celeron T3000 1.8 3 Gig of Ram and Native Intel Intergrated graphics card. Can I run Ubuntu on this machine without any problems? 2.I am windows user and currently have windows 8. I want to install ubuntu but want to save all my directories on C:\ D:\ disks so that I can open my files in ubuntu. Is it possible to save my current directory system and save all my files after installing ubuntu? Can I open all my files? I have very important data in files so I dont want to lose them at all :) Thank You

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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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  • io Exception error in wordcount example

    - by Anitha
    I have installed Hadoop 1.0.3 in Ubuntu 12.04 version (64bit) based on michael-noll.com/tutorials/running-hadoop-on-ubuntu-linux-single-node-cluster/ . I am trying to run a mapreduce job using the wordcount example. Running the command hduser@ubuntu: $/usr/local/hadoop/bin/hadoop jar hadoop-examples-1.0.3.jar wordcount /user/hduser/gutenberg /user/hduser/gutenberg-output gives the following error: Warning: $HADOOP_HOME is deprecated. Exception in thread "main" java.io.IOException: Error opening job jar: hadoop-examples-1.0.3.jar at org.apache.hadoop.util.RunJar.main(RunJar.java:90) Caused by: java.util.zip.ZipException: error in opening zip file at java.util.zip.ZipFile.open(Native Method) at java.util.zip.ZipFile.<init>(ZipFile.java:131) at java.util.jar.JarFile.<init>(JarFile.java:150) at java.util.jar.JarFile.<init>(JarFile.java:87) at org.apache.hadoop.util.RunJar.main(RunJar.java:88) Thanks in advance.

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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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  • Will dolphins die if I use REST "as CRUD"?

    - by l0l0l0l0l
    Recently I moved to Laravel and I was surprised on how good setting the controllers as RESTful is, it made routes and my code cleaner. I'm kinda new on web development and never used REST before since all my clients' projects are basically CRUD operations. There's any cool buzzword to this "approach" or I'm just stupid for doing it? I don't plan to follow any REST patterns, just to make my life easier and code cleaner. Basicallly just GET/POST, the other ones are not native anyway so (emulated on hidden form value).

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  • Add SQL Azure database to Azure Web Role and persist data with entity framework code first.

    - by MagnusKarlsson
    In my last post I went for a warts n all approach to set up a web role on Azure. In this post I’ll describe how to add an SQL Azure database to the project. This will be described with an as minimal as possible amount of code and screen dumps. All questions are welcome in the comments area. Please don’t email since questions answered in the comments field is made available to other visitors. As an example we will add a comments section to the site we used in the previous post (Länk här). Steps: 1. Create a Comments entity and then use Scaffolding to set up controller and view, and add ConnectionString to web.config. 2. Create SQL Azure database in Management Portal and link the new database 3. Test it online!   1. Right click Models folder, choose add, choose “class…” . Name the Class Comment. 1.1 Replace the Code in the class with the following: using System.Data.Entity; namespace MvcWebRole1.Models { public class Comment {    public int CommentId { get; set; }    public string Name { get; set; }      public string Content { get; set; } } public class CommentsDb : DbContext { public DbSet<Comment> CommentEntries { get; set; } } } Now Entity Framework can create a database and a table named Comment. Build your project to assert there are no build errors.   1.2 Right click Controllers folder, choose add, choose “class…” . Name the Class CommentController and fill out the values as in the example below.     1.3 Click Add. Visual Studio now creates default View for CRUD operations and a Controller adhering to these and opens them. 1.3 Open Web.config and add the following connectionstring in <connectionStrings> node. <add name="CommentsDb” connectionString="data source=(LocalDB)\v11.0;Integrated Security=SSPI;AttachDbFileName=|DataDirectory|\CommentsDb.mdf;Initial Catalog=CommentsDb;MultipleActiveResultSets=True" providerName="System.Data.SqlClient" />   1.4 Save All and press F5 to start the application. 1.5 Go to http://127.0.0.1:81/Comments which will redirect you through CommentsController to the Index View which looks like this:     Click Create new. In the Create-view, add name and content and press Create.   1: // 2: // POST: /Comments/Create 3:  4: [HttpPost] 5: public ActionResult Create(Comment comment) 6: { 7: if (ModelState.IsValid) 8: { 9: db.CommentEntries.Add(comment); 10: db.SaveChanges(); 11: return RedirectToAction("Index"); 12: } 13:  14: return View(comment); 15: } 16:    The default View() is Index so that is the View you will come to. Looking like this: 1: // 2: // GET: /Comments/ 3: 4: public ActionResult Index() 5: { 6: return View(db.CommentEntries.ToList()); 7: } Resulting in the following screen dump(success!):   2. Now, go to the Management portal and Create a new db.   2.1 With the new database created. Click the DB icon in the left most menu. Then click the newly created database. Click DASHBOARD in the top menu. Finally click Connections strings in the right menu to get the connection string we need to add in our web.debug.config file.   2.2 Now, take a copy of the connection String earlier added to the web.config and paste in web.debug.conifg in the connectionstrings node. Replace everything within “ “ in the copied connectionstring with that you got from SQL Azure. You will have something like this:   2.3 Rebuild the application, right click the cloud project and choose “Package…” (if you haven’t set up publishing profile which we will do in our next blog post). Remember to choose the right config file, use debug for staging and release for production so your databases won’t collide. You should see something like this:   2.4 Go to Management Portal and click the Web Services menu, choose your service and click update in the bottom menu.   2.5 Link the newly created database to your application. Click the LINKED RESOURCES in the top menu and then click “Link” in the bottom menu. You should get something like this. 3. Alright then. Under the Dashboard you can find the link to your application. Click it to open it in a browser and then go to ~/Comments to try it out just the way we did locally. Success and end of this story!

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  • USB Logitech Rumble Pad 2 gamepad AND Thustmaster Universal Challenge Wheel not working in wine

    - by Rick Gionfriddo
    The controller is detected by the OS, and shows up in lsusb, and I can configure it with jstest-gtk, but Live For Speed in Wine doesn't recognize it as connected. Using Lubuntu 12.04, wine version 1.5.5. P.S. - It worked on a previous install of regular Ubuntu 12.04, using the same Wine version. Have tried installing/overriding/un-overriding various DLL's through winetricks to no avail, including xact and dinput8. Since it worked in a previous install of the same version, I figured it was a configuration error, and that I should ask here as opposed to put in a bug report on winehq. EDIT: I just used both controllers in TORCS... why do they work in native games, but not in wine?

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  • Can i create a SDL_Surface as i do with Allegro?

    - by Petris Rodrigo Fernandes
    First of all, I'm sorry about my english (Isn't my native language) Using allegro I can create a Bitmap to draw just doing: BITMAP* bmp = NULL; bmp = create_bitmap(width,height); // I don't remember exactly the parameters I'm using SDL now, and i want create a SDL_Surface to draw the game level (that is static) creating a SDL_Surface, drawing the tiles on it, then i just blit this surface to the screen instead of keep drawing the tiles directly on screen (i believe this will require more processing); There a way to create a blank SDL_Surface as i did with Allegro just do draw before blit it?

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