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  • numeric choice field:How to let the user set a value by incrementing/decrementing the displayed valu

    - by con_9
    Hi,I have a range say,1-100 and i want the user to select a value from this range.Ofcourse showing this with a spinner will be awful.I want to use the functionality of date widget,where we can pick a date by pressing a +/- sign,the longer the press ,higher the iteration speed. I found numberpicker.java that has the code the date widget uses to get this functionality, but do i have to paste that entire code to achieve this functionality!

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  • How is the result of openssl_sign() encoded?

    - by Bozho
    The docs about openssl_sign() say that the signature is returned in the passed string argument. My question is - how is it encoded? Base64, Hex-string, anything else? I don't have php installed and I have to use this PHP code I was given simply in order to verify whether my Java implementation is correct, so don't ask me "have you tried it" ;)

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  • remove repeated vaules _stack&array

    - by Fatimah
    I want to write a program to implement an array-based stack, which accept integer numbers entered by the user.the program will then identify any occurrences of a given value from user and remove the repeated values from the stack,(using Java programming language). I just need your help of writing (removing values method) e.g. input:6 2 3 4 3 8 output:6 2 4 8

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  • What is Loglevel debug?

    - by Webnet
    My error.log file for my site says Request exceeded the limit of 10 internal redirects due to probable configuration error. Use 'LimitInternalRecursion' to increase the limit if necessary. Use 'LogLevel debug' to get a backtrace., referer: http://URL/TO/REFERER My question is, what is LogLevel? I've googled it but it seems like I'm just getting things about java. Our site is in PHP.

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  • detect when a webpage is updated

    - by Martin Trigaux
    Hello, There is a website (very simple) which will be updated soon and I'd like to receive an alert at the moment it changes (like a sound, a popup,...) I guess I should send request every x minutes and compare the result with what's now but I don't know how to do that. I don't really care about the language used, I know java, python, php, a bit of c and bash (I'm on linux)... Thank you

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  • Communicating Between .NET Programs

    - by IronManIngellis
    I wanted to set up a simple data communication between two C# applications, and I'm not sure what the best method is in doing so. I've previously used Java Sockets and ServerSockets to get the job done, but I'm new to C#, so I've come for advice :) It's going to be two way communication with two clients exchanging strings or something of the like.

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  • it is very important for me this problem [closed]

    - by davit-datuashvili
    please help this is very important problem for me i am going to get job and need such kind of practise implement heaps priortiy queue and so on what is wrong in my java code please tell i want insert number with heap property and return minimum element what is wrong explain please look http://stackoverflow.com/questions/2902781/priority-queue-implementation/2903288#2903288

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  • Disable Clipboard & Print Screen on webpage

    - by air
    i search online but can't get satisfactory result i want to protect images on my website, i know i can disable save as, right click. the real question is can we Disable Clipboard & Print Screen with JQUERY or java script. so no image copy from print screen. thanks

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  • Huge performance difference between two web servers, odd behavior seen using process monitor

    - by Francis Gagnon
    We have two Coldfusion servers that have a huge performance difference running the exact same code on the exact same input data. The code in questions instantiates a large amount of CFCs (Coldfusion Components, which are similar to objects in OOP languages). I compared the two servers by running Process Monitor and then calling the problematic code on both machines. I learned two things. First, Coldfusion opens CFC files every time it instantiates an object. Both servers do this, so it cannot be the cause of the performance difference. Second, the fast server opens the CFC files directly while the server with the performance problem seems to navigate its way through the path until it reaches the desired CFC file. It does this for every file, even the ones it has previously loaded, and because the code instantiates so many CFCs it becomes very slow. See below the partial Promon traces that show this behavior. It can take over 60 seconds for the slow server to do what the fast one does in 2 seconds. Can anyone tell me what causes this behavior? Is it a Coldfusion setting? Since Coldfusion runs on top of Java, is it a Java setting? Is it an OS option? The fast server is running Windows XP and I think the slow server is a Windows Server 2003. Bonus question: Coldfusion doesn't seem to perform any READ FILE operations on any of the CFC or CFM files. How can this be? Sample of the fast server opening CFC files: 11:25:14.5588975 jrun.exe QueryOpen C:\CF\wwwroot\APP\com\HtmlUtils.cfc 11:25:14.5592758 jrun.exe CreateFile C:\CF\wwwroot\APP\com\HtmlUtils.cfc 11:25:14.5595024 jrun.exe QueryBasicInformationFile C:\CF\wwwroot\APP\com\HtmlUtils.cfc 11:25:14.5595940 jrun.exe CloseFile C:\CF\wwwroot\APP\com\HtmlUtils.cfc 11:25:14.5599628 jrun.exe CreateFile C:\CF\wwwroot\APP\com\HtmlUtils.cfc 11:25:14.5601600 jrun.exe QueryBasicInformationFile C:\CF\wwwroot\APP\com\HtmlUtils.cfc 11:25:14.5602463 jrun.exe CloseFile C:\CF\wwwroot\APP\com\HtmlUtils.cfc Equivalent sample of the slow server opening CFC files: 11:15:08.1249230 jrun.exe CreateFile D:\ 11:15:08.1250100 jrun.exe QueryDirectory D:\org 11:15:08.1252852 jrun.exe CloseFile D:\ 11:15:08.1259670 jrun.exe CreateFile D:\org 11:15:08.1260319 jrun.exe QueryDirectory D:\org\cli 11:15:08.1260769 jrun.exe CloseFile D:\org 11:15:08.1269451 jrun.exe CreateFile D:\org\cli 11:15:08.1270613 jrun.exe QueryDirectory D:\org\cli\cpn 11:15:08.1271140 jrun.exe CloseFile D:\org\cli 11:15:08.1279312 jrun.exe CreateFile D:\org\cli\cpn 11:15:08.1280086 jrun.exe QueryDirectory D:\org\cli\cpn\APP 11:15:08.1280789 jrun.exe CloseFile D:\org\cli\cpn 11:15:08.1291034 jrun.exe CreateFile D:\org\cli\cpn\APP 11:15:08.1291709 jrun.exe QueryDirectory D:\org\cli\cpn\APP\com 11:15:08.1292224 jrun.exe CloseFile D:\org\cli\cpn\APP 11:15:08.1300568 jrun.exe CreateFile D:\org\cli\cpn\APP\com 11:15:08.1301321 jrun.exe QueryDirectory D:\org\cli\cpn\APP\com\HtmlUtils.cfc 11:15:08.1301843 jrun.exe CloseFile D:\org\cli\cpn\APP\com 11:15:08.1312049 jrun.exe CreateFile D:\org\cli\cpn\APP\com\HtmlUtils.cfc 11:15:08.1314409 jrun.exe QueryBasicInformationFile D:\org\cli\cpn\APP\com\HtmlUtils.cfc 11:15:08.1314633 jrun.exe CloseFile D:\org\cli\cpn\APP\com\HtmlUtils.cfc 11:15:08.1315881 jrun.exe CreateFile D:\ 11:15:08.1316379 jrun.exe QueryDirectory D:\org 11:15:08.1316926 jrun.exe CloseFile D:\ 11:15:08.1330951 jrun.exe CreateFile D:\org 11:15:08.1338656 jrun.exe QueryDirectory D:\org\cli 11:15:08.1339118 jrun.exe CloseFile D:\org 11:15:08.1526468 jrun.exe CreateFile D:\org\cli 11:15:08.1527295 jrun.exe QueryDirectory D:\org\cli\cpn 11:15:08.1527989 jrun.exe CloseFile D:\org\cli 11:15:08.1531977 jrun.exe CreateFile D:\org\cli\cpn 11:15:08.1532589 jrun.exe QueryDirectory D:\org\cli\cpn\APP 11:15:08.1533575 jrun.exe CloseFile D:\org\cli\cpn 11:15:08.1538457 jrun.exe CreateFile D:\org\cli\cpn\APP 11:15:08.1539083 jrun.exe QueryDirectory D:\org\cli\cpn\APP\com 11:15:08.1539553 jrun.exe CloseFile D:\org\cli\cpn\APP 11:15:08.1544126 jrun.exe CreateFile D:\org\cli\cpn\APP\com 11:15:08.1544980 jrun.exe QueryDirectory D:\org\cli\cpn\APP\com\HtmlUtils.cfc 11:15:08.1545482 jrun.exe CloseFile D:\org\cli\cpn\APP\com 11:15:08.1551034 jrun.exe CreateFile D:\org\cli\cpn\APP\com\HtmlUtils.cfc 11:15:08.1552878 jrun.exe QueryBasicInformationFile D:\org\cli\cpn\APP\com\HtmlUtils.cfc 11:15:08.1553044 jrun.exe CloseFile D:\org\cli\cpn\APP\com\HtmlUtils.cfc Thanks

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  • What is consuming so much memory?

    - by Christopher
    Hi, I am having a few problems with my server. It is throwing up intermittant errors and running quite slow. Here is the output from top: top - 07:33:33 up 18:57, 1 user, load average: 0.00, 0.00, 0.00 Tasks: 90 total, 1 running, 82 sleeping, 7 stopped, 0 zombie Cpu(s): 0.0%us, 0.0%sy, 0.0%ni,100.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st Mem: 1048576k total, 1048576k used, 0k free, 0k buffers Swap: 0k total, 0k used, 0k free, 0k cached Ordered by %MEM: PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 9597 root 16 0 276m 91m 15m S 0.0 8.9 0:29.38 java 9564 tomcat 15 0 249m 34m 11m S 0.0 3.4 0:11.79 java 9636 root 18 0 54804 24m 9784 S 0.0 2.4 0:02.58 httpd 26139 apache 15 0 57520 23m 5996 S 0.0 2.3 0:00.15 httpd 16264 apache 18 0 56984 23m 6104 S 0.0 2.2 0:00.21 httpd 24294 apache 15 0 57512 22m 5864 S 0.0 2.2 0:00.17 httpd 30231 apache 15 0 57272 22m 5748 S 0.0 2.2 0:00.97 httpd 32257 apache 15 0 57512 22m 5416 S 0.0 2.2 0:00.46 httpd 19947 apache 15 0 57512 22m 5320 S 0.0 2.2 0:00.19 httpd 26148 apache 15 0 56688 22m 5992 S 0.0 2.2 0:00.40 httpd 14039 apache 18 0 57000 22m 5492 S 0.0 2.2 0:00.33 httpd 6051 apache 15 0 57736 22m 5128 S 0.0 2.2 0:00.07 httpd 19937 apache 15 0 56992 22m 5400 S 0.0 2.2 0:00.14 httpd 5200 apache 15 0 56984 22m 5376 S 0.0 2.2 0:00.23 httpd 10001 apache 15 0 55636 21m 5636 S 0.0 2.1 0:01.05 httpd 11734 apache 15 0 56712 21m 4548 S 0.0 2.1 0:00.46 httpd 18193 apache 15 0 55100 20m 5508 S 0.0 2.0 0:00.24 httpd 14036 apache 15 0 55128 20m 5412 S 0.0 2.0 0:00.10 httpd 3981 apache 15 0 55128 19m 4860 S 0.0 1.9 0:00.16 httpd 7588 apache 18 0 55112 19m 4848 S 0.0 1.9 0:00.04 httpd 19768 apache 16 0 55112 19m 4844 S 0.0 1.9 0:00.02 httpd 5827 apache 15 0 55112 19m 4828 S 0.0 1.9 0:00.05 httpd 29774 apache 15 0 55112 19m 4544 S 0.0 1.9 0:00.11 httpd 6064 apache 15 0 55112 19m 4536 S 0.0 1.9 0:00.02 httpd 16253 apache 17 0 55116 19m 4532 S 0.0 1.9 0:00.01 httpd 19922 apache 15 0 55112 19m 4540 S 0.0 1.9 0:00.02 httpd 10010 apache 15 0 55100 19m 4524 S 0.0 1.9 0:00.01 httpd 18195 apache 18 0 55104 18m 3872 S 0.0 1.8 0:00.02 httpd 7361 mysql 15 0 134m 18m 6400 S 0.0 1.8 0:10.18 mysqld 19921 apache 15 0 55088 18m 3588 S 0.0 1.8 0:00.02 httpd 11967 apache 15 0 55080 18m 3584 S 0.0 1.8 0:00.00 httpd 13813 apache 15 0 55088 18m 3576 S 0.0 1.8 0:00.14 httpd 23898 apache 18 0 54968 17m 3212 S 0.0 1.7 0:00.00 httpd 13792 apache 15 0 54968 17m 3088 S 0.0 1.7 0:00.00 httpd 14083 apache 15 0 54968 17m 3088 S 0.0 1.7 0:00.00 httpd 32547 apache 15 0 54944 17m 2924 S 0.0 1.7 0:00.00 httpd 13787 apache 15 0 54944 17m 2908 S 0.0 1.7 0:00.00 httpd 3623 apache 17 0 54944 17m 2908 S 0.0 1.7 0:00.00 httpd 16024 apache 19 0 54944 17m 2860 S 0.0 1.7 0:00.00 httpd 13791 apache 15 0 54944 17m 2864 S 0.0 1.7 0:00.00 httpd 20090 named 19 0 110m 4244 2056 S 0.0 0.4 0:01.55 named 9369 cyrus 15 0 15904 3048 1720 S 0.0 0.3 0:00.24 cyrus-master 32735 root 15 0 8852 2888 2116 T 0.0 0.3 0:00.00 mysql The intermittant error I get using Firefox is: Server not found Firefox can't find the server at XXXXXXX.co. * Check the address for typing errors such as ww.example.com instead of www.example.com * If you are unable to load any pages, check your computer's network connection. * If your computer or network is protected by a firewall or proxy, make sure that Firefox is permitted to access the Web. And on other browsers, the page just loads for about 10 minutes but never appears. The only way to resolve it is to close the browser completely as the error appears to be saved in the cache. Has anyone got any ideas? Many Thanks.

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  • Python in command line runs the wrong version?

    - by Deflect
    I have several versions of Python installed on a Windows 7 computer. I want to run Python 2.7 by default, but for whatever reason, typing python in the command line runs Python version 2.4.5. I've tried adding C:\Python27 to my system path variable as per this question, and manually combed my path variable it to make sure Python 2.4.5 wasn't tossed in there by mistake, but that didn't fix the issue. I have to type in C:\Python27\python.exe every time I want to access the correct version of python I want. What other places can I check? How can I make the command line use the correct version of python? I also found this but it's not for windows. [EDIT] My path (separated by semicolons): C:\Program Files\Common Files\Microsoft Shared\Windows Live; C:\Program Files (x86)\Common Files\Microsoft Shared\Windows Live; C:\Windows\system32; C:\Windows; C:\Windows\System32\Wbem; C:\Windows\System32\WindowsPowerShell\v1.0\; C:\Program Files\Dell\DW WLAN Card\Driver; C:\Program Files (x86)\Common Files\Roxio Shared\DLLShared\; C:\Program Files (x86)\Windows Live\Shared; c:\Program Files (x86)\Microsoft SQL Server\100\Tools\Binn\; c:\Program Files\Microsoft SQL Server\100\Tools\Binn\; c:\Program Files\Microsoft SQL Server\100\DTS\Binn\; C:\Program Files\TortoiseGit\bin; C:\Program Files\Java\jdk1.6.0_26\bin; C:\Program Files\Java\jdk1.6.0_21 ; C:\Program Files\IVI Foundation\VISA\Win64\Bin\; C:\Program Files (x86)\IVI Foundation\VISA\WinNT\Bin\; C:\Program Files (x86)\IVI Foundation\VISA\WinNT\Bin; C:\Program Files\WPIJavaCV\OpenCV_2.2.0\bin; C:\Program Files (x86)\LilyPond\usr\bin; C:\Program Files\TortoiseSVN\bin; C:\Program Files (x86)\doxygen\bin; C:\Program Files (x86)\Graphviz 2.28\bin; C:\Users\Michael\bin\Misc\cppcheck\; C:\Program Files (x86)\Git\cmd; C:\Python27\python.exe; C:\Ruby192\bin; C:\Users\Michael\AppData\Roaming\cabal\bin; C:\Python27\; [EDIT 2] Running python spews this out: 'import site' failed; used -v for traceback Python 2.4.5 (#1, Jul 22 2011, 02:01:04) [GCC 4.1.1] on mingw32 Type "help", "copyright", "credits" or "license" for more information. >>> ...and running python --version (as suggested below) seems to be an unrecognized option. (I also tried running python -v, and it appears that Python 2.4 is trying to import libraries from C:\Python27\Lib, and failed due to a syntax error when it encountered a with statement, which was added in later version, I think) Also, I'm not sure if it's significant or not, but the above python version says something about GCC and mingw32, while running C:\python27\python.exe shows this: Python 2.7.2 (default, Jun 12 2011, 15:08:59) [MSC v.1500 32 bit (Intel)] on win32 Type "help", "copyright", "credits" or "license" for more information. >>>>

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  • Screen -X exec commands not working until manually attached

    - by James Watt
    I have a batch script that starts a java server application inside of a screen. The command looks like this: cd /dir/ && screen -A -m -d -S javascreen java -Xms640M -Xmx1024M -jar javaserverapp.jar nogui After I run the batch script, it starts the server and puts it inside the correct screen. If I list my screens after, I see something like this: user@gtwy /dir $ screen -list There is a screen on: 16180.javascreen (Detached) 1 Socket in /var/run/screen/S-user. However, I have a second batch script that sends automated commands to this server and runs on a different crontab interval. Because of the way the application works, I send commands to it like this (this command tells it to alert connected users "testing 123"): screen -X exec .\!\! echo say testing 123 I've also tried: screen -R -X exec .\!\! echo say testing 123 screen -S javascreen -X exec .\!\! echo say testing 123 Unfortunately, these commands DO NOT WORK. They don't even give me an error message, they just do nothing. HOWEVER - If I manually attach to the screen first (with the below command) and then detach, now I can run any of the above commands flawlessly. I can demonstrate this with a video, if I wasn't clear enough here. screen -r -d Thanks in advance. Update: here is the important parts of /etc/screenrc. It should be totally vanilla, I've never edited this file. # VARIABLES # =============================================================== # No annoying audible bell, using "visual bell" # vbell on # default: off # vbell_msg " -- Bell,Bell!! -- " # default: "Wuff,Wuff!!" # Automatically detach on hangup. autodetach on # default: on # Don't display the copyright page startup_message off # default: on # Uses nethack-style messages # nethack on # default: off # Affects the copying of text regions crlf off # default: off # Enable/disable multiuser mode. Standard screen operation is singleuser. # In multiuser mode the commands acladd, aclchg, aclgrp and acldel can be used # to enable (and disable) other user accessing this screen session. # Requires suid-root. multiuser off # Change default scrollback value for new windows defscrollback 1000 # default: 100 # Define the time that all windows monitored for silence should # wait before displaying a message. Default 30 seconds. silencewait 15 # default: 30 # bufferfile: The file to use for commands # "readbuf" ('<') and "writebuf" ('>'): bufferfile $HOME/.screen_exchange # # hardcopydir: The directory which contains all hardcopies. # hardcopydir ~/.hardcopy # hardcopydir ~/.screen # # shell: Default process started in screen's windows. # Makes it possible to use a different shell inside screen # than is set as the default login shell. # If begins with a '-' character, the shell will be started as a login shell. # shell zsh # shell bash # shell ksh shell -$SHELL # shellaka '> |tcsh' # shelltitle '$ |bash' # emulate .logout message pow_detach_msg "Screen session of \$LOGNAME \$:cr:\$:nl:ended." # caption always " %w --- %c:%s" # caption always "%3n %t%? @%u%?%? [%h]%?%=%c" # advertise hardstatus support to $TERMCAP # termcapinfo * '' 'hs:ts=\E_:fs=\E\\:ds=\E_\E\\' # set every new windows hardstatus line to somenthing descriptive # defhstatus "screen: ^En (^Et)" # don't kill window after the process died # zombie "^["

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  • Where does ASP.NET Web API Fit?

    - by Rick Strahl
    With the pending release of ASP.NET MVC 4 and the new ASP.NET Web API, there has been a lot of discussion of where the new Web API technology fits in the ASP.NET Web stack. There are a lot of choices to build HTTP based applications available now on the stack - we've come a long way from when WebForms and Http Handlers/Modules where the only real options. Today we have WebForms, MVC, ASP.NET Web Pages, ASP.NET AJAX, WCF REST and now Web API as well as the core ASP.NET runtime to choose to build HTTP content with. Web API definitely squarely addresses the 'API' aspect - building consumable services - rather than HTML content, but even to that end there are a lot of choices you have today. So where does Web API fit, and when doesn't it? But before we get into that discussion, let's talk about what a Web API is and why we should care. What's a Web API? HTTP 'APIs' (Microsoft's new terminology for a service I guess)  are becoming increasingly more important with the rise of the many devices in use today. Most mobile devices like phones and tablets run Apps that are using data retrieved from the Web over HTTP. Desktop applications are also moving in this direction with more and more online content and synching moving into even traditional desktop applications. The pending Windows 8 release promises an app like platform for both the desktop and other devices, that also emphasizes consuming data from the Cloud. Likewise many Web browser hosted applications these days are relying on rich client functionality to create and manipulate the browser user interface, using AJAX rather than server generated HTML data to load up the user interface with data. These mobile or rich Web applications use their HTTP connection to return data rather than HTML markup in the form of JSON or XML typically. But an API can also serve other kinds of data, like images or other binary files, or even text data and HTML (although that's less common). A Web API is what feeds rich applications with data. ASP.NET Web API aims to service this particular segment of Web development by providing easy semantics to route and handle incoming requests and an easy to use platform to serve HTTP data in just about any content format you choose to create and serve from the server. But .NET already has various HTTP Platforms The .NET stack already includes a number of technologies that provide the ability to create HTTP service back ends, and it has done so since the very beginnings of the .NET platform. From raw HTTP Handlers and Modules in the core ASP.NET runtime, to high level platforms like ASP.NET MVC, Web Forms, ASP.NET AJAX and the WCF REST engine (which technically is not ASP.NET, but can integrate with it), you've always been able to handle just about any kind of HTTP request and response with ASP.NET. The beauty of the raw ASP.NET platform is that it provides you everything you need to build just about any type of HTTP application you can dream up from low level APIs/custom engines to high level HTML generation engine. ASP.NET as a core platform clearly has stood the test of time 10+ years later and all other frameworks like Web API are built on top of this ASP.NET core. However, although it's possible to create Web APIs / Services using any of the existing out of box .NET technologies, none of them have been a really nice fit for building arbitrary HTTP based APIs. Sure, you can use an HttpHandler to create just about anything, but you have to build a lot of plumbing to build something more complex like a comprehensive API that serves a variety of requests, handles multiple output formats and can easily pass data up to the server in a variety of ways. Likewise you can use ASP.NET MVC to handle routing and creating content in various formats fairly easily, but it doesn't provide a great way to automatically negotiate content types and serve various content formats directly (it's possible to do with some plumbing code of your own but not built in). Prior to Web API, Microsoft's main push for HTTP services has been WCF REST, which was always an awkward technology that had a severe personality conflict, not being clear on whether it wanted to be part of WCF or purely a separate technology. In the end it didn't do either WCF compatibility or WCF agnostic pure HTTP operation very well, which made for a very developer-unfriendly environment. Personally I didn't like any of the implementations at the time, so much so that I ended up building my own HTTP service engine (as part of the West Wind Web Toolkit), as have a few other third party tools that provided much better integration and ease of use. With the release of Web API for the first time I feel that I can finally use the tools in the box and not have to worry about creating and maintaining my own toolkit as Web API addresses just about all the features I implemented on my own and much more. ASP.NET Web API provides a better HTTP Experience ASP.NET Web API differentiates itself from the previous Microsoft in-box HTTP service solutions in that it was built from the ground up around the HTTP protocol and its messaging semantics. Unlike WCF REST or ASP.NET AJAX with ASMX, it’s a brand new platform rather than bolted on technology that is supposed to work in the context of an existing framework. The strength of the new ASP.NET Web API is that it combines the best features of the platforms that came before it, to provide a comprehensive and very usable HTTP platform. Because it's based on ASP.NET and borrows a lot of concepts from ASP.NET MVC, Web API should be immediately familiar and comfortable to most ASP.NET developers. Here are some of the features that Web API provides that I like: Strong Support for URL Routing to produce clean URLs using familiar MVC style routing semantics Content Negotiation based on Accept headers for request and response serialization Support for a host of supported output formats including JSON, XML, ATOM Strong default support for REST semantics but they are optional Easily extensible Formatter support to add new input/output types Deep support for more advanced HTTP features via HttpResponseMessage and HttpRequestMessage classes and strongly typed Enums to describe many HTTP operations Convention based design that drives you into doing the right thing for HTTP Services Very extensible, based on MVC like extensibility model of Formatters and Filters Self-hostable in non-Web applications  Testable using testing concepts similar to MVC Web API is meant to handle any kind of HTTP input and produce output and status codes using the full spectrum of HTTP functionality available in a straight forward and flexible manner. Looking at the list above you can see that a lot of functionality is very similar to ASP.NET MVC, so many ASP.NET developers should feel quite comfortable with the concepts of Web API. The Routing and core infrastructure of Web API are very similar to how MVC works providing many of the benefits of MVC, but with focus on HTTP access and manipulation in Controller methods rather than HTML generation in MVC. There’s much improved support for content negotiation based on HTTP Accept headers with the framework capable of detecting automatically what content the client is sending and requesting and serving the appropriate data format in return. This seems like such a little and obvious thing, but it's really important. Today's service backends often are used by multiple clients/applications and being able to choose the right data format for what fits best for the client is very important. While previous solutions were able to accomplish this using a variety of mixed features of WCF and ASP.NET, Web API combines all this functionality into a single robust server side HTTP framework that intrinsically understands the HTTP semantics and subtly drives you in the right direction for most operations. And when you need to customize or do something that is not built in, there are lots of hooks and overrides for most behaviors, and even many low level hook points that allow you to plug in custom functionality with relatively little effort. No Brainers for Web API There are a few scenarios that are a slam dunk for Web API. If your primary focus of an application or even a part of an application is some sort of API then Web API makes great sense. HTTP ServicesIf you're building a comprehensive HTTP API that is to be consumed over the Web, Web API is a perfect fit. You can isolate the logic in Web API and build your application as a service breaking out the logic into controllers as needed. Because the primary interface is the service there's no confusion of what should go where (MVC or API). Perfect fit. Primary AJAX BackendsIf you're building rich client Web applications that are relying heavily on AJAX callbacks to serve its data, Web API is also a slam dunk. Again because much if not most of the business logic will probably end up in your Web API service logic, there's no confusion over where logic should go and there's no duplication. In Single Page Applications (SPA), typically there's very little HTML based logic served other than bringing up a shell UI and then filling the data from the server with AJAX which means the business logic required for data retrieval and data acceptance and validation too lives in the Web API. Perfect fit. Generic HTTP EndpointsAnother good fit are generic HTTP endpoints that to serve data or handle 'utility' type functionality in typical Web applications. If you need to implement an image server, or an upload handler in the past I'd implement that as an HTTP handler. With Web API you now have a well defined place where you can implement these types of generic 'services' in a location that can easily add endpoints (via Controller methods) or separated out as more full featured APIs. Granted this could be done with MVC as well, but Web API seems a clearer and more well defined place to store generic application services. This is one thing I used to do a lot of in my own libraries and Web API addresses this nicely. Great fit. Mixed HTML and AJAX Applications: Not a clear Choice  For all the commonality that Web API and MVC share they are fundamentally different platforms that are independent of each other. A lot of people have asked when does it make sense to use MVC vs. Web API when you're dealing with typical Web application that creates HTML and also uses AJAX functionality for rich functionality. While it's easy to say that all 'service'/AJAX logic should go into a Web API and all HTML related generation into MVC, that can often result in a lot of code duplication. Also MVC supports JSON and XML result data fairly easily as well so there's some confusion where that 'trigger point' is of when you should switch to Web API vs. just implementing functionality as part of MVC controllers. Ultimately there's a tradeoff between isolation of functionality and duplication. A good rule of thumb I think works is that if a large chunk of the application's functionality serves data Web API is a good choice, but if you have a couple of small AJAX requests to serve data to a grid or autocomplete box it'd be overkill to separate out that logic into a separate Web API controller. Web API does add overhead to your application (it's yet another framework that sits on top of core ASP.NET) so it should be worth it .Keep in mind that MVC can generate HTML and JSON/XML and just about any other content easily and that functionality is not going away, so just because you Web API is there it doesn't mean you have to use it. Web API is not a full replacement for MVC obviously either since there's not the same level of support to feed HTML from Web API controllers (although you can host a RazorEngine easily enough if you really want to go that route) so if you're HTML is part of your API or application in general MVC is still a better choice either alone or in combination with Web API. I suspect (and hope) that in the future Web API's functionality will merge even closer with MVC so that you might even be able to mix functionality of both into single Controllers so that you don't have to make any trade offs, but at the moment that's not the case. Some Issues To think about Web API is similar to MVC but not the Same Although Web API looks a lot like MVC it's not the same and some common functionality of MVC behaves differently in Web API. For example, the way single POST variables are handled is different than MVC and doesn't lend itself particularly well to some AJAX scenarios with POST data. Code Duplication I already touched on this in the Mixed HTML and Web API section, but if you build an MVC application that also exposes a Web API it's quite likely that you end up duplicating a bunch of code and - potentially - infrastructure. You may have to create authentication logic both for an HTML application and for the Web API which might need something different altogether. More often than not though the same logic is used, and there's no easy way to share. If you implement an MVC ActionFilter and you want that same functionality in your Web API you'll end up creating the filter twice. AJAX Data or AJAX HTML On a recent post's comments, David made some really good points regarding the commonality of MVC and Web API's and its place. One comment that caught my eye was a little more generic, regarding data services vs. HTML services. David says: I see a lot of merit in the combination of Knockout.js, client side templates and view models, calling Web API for a responsive UI, but sometimes late at night that still leaves me wondering why I would no longer be using some of the nice tooling and features that have evolved in MVC ;-) You know what - I can totally relate to that. On the last Web based mobile app I worked on, we decided to serve HTML partials to the client via AJAX for many (but not all!) things, rather than sending down raw data to inject into the DOM on the client via templating or direct manipulation. While there are definitely more bytes on the wire, with this, the overhead ended up being actually fairly small if you keep the 'data' requests small and atomic. Performance was often made up by the lack of client side rendering of HTML. Server rendered HTML for AJAX templating gives so much better infrastructure support without having to screw around with 20 mismatched client libraries. Especially with MVC and partials it's pretty easy to break out your HTML logic into very small, atomic chunks, so it's actually easy to create small rendering islands that can be used via composition on the server, or via AJAX calls to small, tight partials that return HTML to the client. Although this is often frowned upon as to 'heavy', it worked really well in terms of developer effort as well as providing surprisingly good performance on devices. There's still plenty of jQuery and AJAX logic happening on the client but it's more manageable in small doses rather than trying to do the entire UI composition with JavaScript and/or 'not-quite-there-yet' template engines that are very difficult to debug. This is not an issue directly related to Web API of course, but something to think about especially for AJAX or SPA style applications. Summary Web API is a great new addition to the ASP.NET platform and it addresses a serious need for consolidation of a lot of half-baked HTTP service API technologies that came before it. Web API feels 'right', and hits the right combination of usability and flexibility at least for me and it's a good fit for true API scenarios. However, just because a new platform is available it doesn't meant that other tools or tech that came before it should be discarded or even upgraded to the new platform. There's nothing wrong with continuing to use MVC controller methods to handle API tasks if that's what your app is running now - there's very little to be gained by upgrading to Web API just because. But going forward Web API clearly is the way to go, when building HTTP data interfaces and it's good to see that Microsoft got this one right - it was sorely needed! Resources ASP.NET Web API AspConf Ask the Experts Session (first 5 minutes) © Rick Strahl, West Wind Technologies, 2005-2012Posted in Web Api   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • Announcing the Release of Visual Studio 2013 and Great Improvements to ASP.NET and Entity Framework

    - by ScottGu
    Today we released VS 2013 and .NET 4.5.1. These releases include a ton of great improvements, and include some fantastic enhancements to ASP.NET and the Entity Framework.  You can download and start using them now. Below are details on a few of the great ASP.NET, Web Development, and Entity Framework improvements you can take advantage of with this release.  Please visit http://www.asp.net/vnext for additional release notes, documentation, and tutorials. One ASP.NET With the release of Visual Studio 2013, we have taken a step towards unifying the experience of using the different ASP.NET sub-frameworks (Web Forms, MVC, Web API, SignalR, etc), and you can now easily mix and match the different ASP.NET technologies you want to use within a single application. When you do a File-New Project with VS 2013 you’ll now see a single ASP.NET Project option: Selecting this project will bring up an additional dialog that allows you to start with a base project template, and then optionally add/remove the technologies you want to use in it.  For example, you could start with a Web Forms template and add Web API or Web Forms support for it, or create a MVC project and also enable Web Forms pages within it: This makes it easy for you to use any ASP.NET technology you want within your apps, and take advantage of any feature across the entire ASP.NET technology span. Richer Authentication Support The new “One ASP.NET” project dialog also includes a new Change Authentication button that, when pushed, enables you to easily change the authentication approach used by your applications – and makes it much easier to build secure applications that enable SSO from a variety of identity providers.  For example, when you start with the ASP.NET Web Forms or MVC templates you can easily add any of the following authentication options to the application: No Authentication Individual User Accounts (Single Sign-On support with FaceBook, Twitter, Google, and Microsoft ID – or Forms Auth with ASP.NET Membership) Organizational Accounts (Single Sign-On support with Windows Azure Active Directory ) Windows Authentication (Active Directory in an intranet application) The Windows Azure Active Directory support is particularly cool.  Last month we updated Windows Azure Active Directory so that developers can now easily create any number of Directories using it (for free and deployed within seconds).  It now takes only a few moments to enable single-sign-on support within your ASP.NET applications against these Windows Azure Active Directories.  Simply choose the “Organizational Accounts” radio button within the Change Authentication dialog and enter the name of your Windows Azure Active Directory to do this: This will automatically configure your ASP.NET application to use Windows Azure Active Directory and register the application with it.  Now when you run the app your users can easily and securely sign-in using their Active Directory credentials within it – regardless of where the application is hosted on the Internet. For more information about the new process for creating web projects, see Creating ASP.NET Web Projects in Visual Studio 2013. Responsive Project Templates with Bootstrap The new default project templates for ASP.NET Web Forms, MVC, Web API and SPA are built using Bootstrap. Bootstrap is an open source CSS framework that helps you build responsive websites which look great on different form factors such as mobile phones, tables and desktops. For example in a browser window the home page created by the MVC template looks like the following: When you resize the browser to a narrow window to see how it would like on a phone, you can notice how the contents gracefully wrap around and the horizontal top menu turns into an icon: When you click the menu-icon above it expands into a vertical menu – which enables a good navigation experience for small screen real-estate devices: We think Bootstrap will enable developers to build web applications that work even better on phones, tablets and other mobile devices – and enable you to easily build applications that can leverage the rich ecosystem of Bootstrap CSS templates already out there.  You can learn more about Bootstrap here. Visual Studio Web Tooling Improvements Visual Studio 2013 includes a new, much richer, HTML editor for Razor files and HTML files in web applications. The new HTML editor provides a single unified schema based on HTML5. It has automatic brace completion, jQuery UI and AngularJS attribute IntelliSense, attribute IntelliSense Grouping, and other great improvements. For example, typing “ng-“ on an HTML element will show the intellisense for AngularJS: This support for AngularJS, Knockout.js, Handlebars and other SPA technologies in this release of ASP.NET and VS 2013 makes it even easier to build rich client web applications: The screen shot below demonstrates how the HTML editor can also now inspect your page at design-time to determine all of the CSS classes that are available. In this case, the auto-completion list contains classes from Bootstrap’s CSS file. No more guessing at which Bootstrap element names you need to use: Visual Studio 2013 also comes with built-in support for both CoffeeScript and LESS editing support. The LESS editor comes with all the cool features from the CSS editor and has specific Intellisense for variables and mixins across all the LESS documents in the @import chain. Browser Link – SignalR channel between browser and Visual Studio The new Browser Link feature in VS 2013 lets you run your app within multiple browsers on your dev machine, connect them to Visual Studio, and simultaneously refresh all of them just by clicking a button in the toolbar. You can connect multiple browsers (including IE, FireFox, Chrome) to your development site, including mobile emulators, and click refresh to refresh all the browsers all at the same time.  This makes it much easier to easily develop/test against multiple browsers in parallel. Browser Link also exposes an API to enable developers to write Browser Link extensions.  By enabling developers to take advantage of the Browser Link API, it becomes possible to create very advanced scenarios that crosses boundaries between Visual Studio and any browser that’s connected to it. Web Essentials takes advantage of the API to create an integrated experience between Visual Studio and the browser’s developer tools, remote controlling mobile emulators and a lot more. You will see us take advantage of this support even more to enable really cool scenarios going forward. ASP.NET Scaffolding ASP.NET Scaffolding is a new code generation framework for ASP.NET Web applications. It makes it easy to add boilerplate code to your project that interacts with a data model. In previous versions of Visual Studio, scaffolding was limited to ASP.NET MVC projects. With Visual Studio 2013, you can now use scaffolding for any ASP.NET project, including Web Forms. When using scaffolding, we ensure that all required dependencies are automatically installed for you in the project. For example, if you start with an ASP.NET Web Forms project and then use scaffolding to add a Web API Controller, the required NuGet packages and references to enable Web API are added to your project automatically.  To do this, just choose the Add->New Scaffold Item context menu: Support for scaffolding async controllers uses the new async features from Entity Framework 6. ASP.NET Identity ASP.NET Identity is a new membership system for ASP.NET applications that we are introducing with this release. ASP.NET Identity makes it easy to integrate user-specific profile data with application data. ASP.NET Identity also allows you to choose the persistence model for user profiles in your application. You can store the data in a SQL Server database or another data store, including NoSQL data stores such as Windows Azure Storage Tables. ASP.NET Identity also supports Claims-based authentication, where the user’s identity is represented as a set of claims from a trusted issuer. Users can login by creating an account on the website using username and password, or they can login using social identity providers (such as Microsoft Account, Twitter, Facebook, Google) or using organizational accounts through Windows Azure Active Directory or Active Directory Federation Services (ADFS). To learn more about how to use ASP.NET Identity visit http://www.asp.net/identity.  ASP.NET Web API 2 ASP.NET Web API 2 has a bunch of great improvements including: Attribute routing ASP.NET Web API now supports attribute routing, thanks to a contribution by Tim McCall, the author of http://attributerouting.net. With attribute routing you can specify your Web API routes by annotating your actions and controllers like this: OAuth 2.0 support The Web API and Single Page Application project templates now support authorization using OAuth 2.0. OAuth 2.0 is a framework for authorizing client access to protected resources. It works for a variety of clients including browsers and mobile devices. OData Improvements ASP.NET Web API also now provides support for OData endpoints and enables support for both ATOM and JSON-light formats. With OData you get support for rich query semantics, paging, $metadata, CRUD operations, and custom actions over any data source. Below are some of the specific enhancements in ASP.NET Web API 2 OData. Support for $select, $expand, $batch, and $value Improved extensibility Type-less support Reuse an existing model OWIN Integration ASP.NET Web API now fully supports OWIN and can be run on any OWIN capable host. With OWIN integration, you can self-host Web API in your own process alongside other OWIN middleware, such as SignalR. For more information, see Use OWIN to Self-Host ASP.NET Web API. More Web API Improvements In addition to the features above there have been a host of other features in ASP.NET Web API, including CORS support Authentication Filters Filter Overrides Improved Unit Testability Portable ASP.NET Web API Client To learn more go to http://www.asp.net/web-api/ ASP.NET SignalR 2 ASP.NET SignalR is library for ASP.NET developers that dramatically simplifies the process of adding real-time web functionality to your applications. Real-time web functionality is the ability to have server-side code push content to connected clients instantly as it becomes available. SignalR 2.0 introduces a ton of great improvements. We’ve added support for Cross-Origin Resource Sharing (CORS) to SignalR 2.0. iOS and Android support for SignalR have also been added using the MonoTouch and MonoDroid components from the Xamarin library (for more information on how to use these additions, see the article Using Xamarin Components from the SignalR wiki). We’ve also added support for the Portable .NET Client in SignalR 2.0 and created a new self-hosting package. This change makes the setup process for SignalR much more consistent between web-hosted and self-hosted SignalR applications. To learn more go to http://www.asp.net/signalr. ASP.NET MVC 5 The ASP.NET MVC project templates integrate seamlessly with the new One ASP.NET experience and enable you to integrate all of the above ASP.NET Web API, SignalR and Identity improvements. You can also customize your MVC project and configure authentication using the One ASP.NET project creation wizard. The MVC templates have also been updated to use ASP.NET Identity and Bootstrap as well. An introductory tutorial to ASP.NET MVC 5 can be found at Getting Started with ASP.NET MVC 5. This release of ASP.NET MVC also supports several nice new MVC-specific features including: Authentication filters: These filters allow you to specify authentication logic per-action, per-controller or globally for all controllers. Attribute Routing: Attribute Routing allows you to define your routes on actions or controllers. To learn more go to http://www.asp.net/mvc Entity Framework 6 Improvements Visual Studio 2013 ships with Entity Framework 6, which bring a lot of great new features to the data access space: Async and Task<T> Support EF6’s new Async Query and Save support enables you to perform asynchronous data access and take advantage of the Task<T> support introduced in .NET 4.5 within data access scenarios.  This allows you to free up threads that might otherwise by blocked on data access requests, and enable them to be used to process other requests whilst you wait for the database engine to process operations. When the database server responds the thread will be re-queued within your ASP.NET application and execution will continue.  This enables you to easily write significantly more scalable server code. Here is an example ASP.NET WebAPI action that makes use of the new EF6 async query methods: Interception and Logging Interception and SQL logging allows you to view – or even change – every command that is sent to the database by Entity Framework. This includes a simple, human readable log – which is great for debugging – as well as some lower level building blocks that give you access to the command and results. Here is an example of wiring up the simple log to Debug in the constructor of an MVC controller: Custom Code-First Conventions The new Custom Code-First Conventions enable bulk configuration of a Code First model – reducing the amount of code you need to write and maintain. Conventions are great when your domain classes don’t match the Code First conventions. For example, the following convention configures all properties that are called ‘Key’ to be the primary key of the entity they belong to. This is different than the default Code First convention that expects Id or <type name>Id. Connection Resiliency The new Connection Resiliency feature in EF6 enables you to register an execution strategy to handle – and potentially retry – failed database operations. This is especially useful when deploying to cloud environments where dropped connections become more common as you traverse load balancers and distributed networks. EF6 includes a built-in execution strategy for SQL Azure that knows about retryable exception types and has some sensible – but overridable – defaults for the number of retries and time between retries when errors occur. Registering it is simple using the new Code-Based Configuration support: These are just some of the new features in EF6. You can visit the release notes section of the Entity Framework site for a complete list of new features. Microsoft OWIN Components Open Web Interface for .NET (OWIN) defines an open abstraction between .NET web servers and web applications, and the ASP.NET “Katana” project brings this abstraction to ASP.NET. OWIN decouples the web application from the server, making web applications host-agnostic. For example, you can host an OWIN-based web application in IIS or self-host it in a custom process. For more information about OWIN and Katana, see What's new in OWIN and Katana. Summary Today’s Visual Studio 2013, ASP.NET and Entity Framework release delivers some fantastic new features that streamline your web development lifecycle. These feature span from server framework to data access to tooling to client-side HTML development.  They also integrate some great open-source technology and contributions from our developer community. Download and start using them today! Scott P.S. In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu

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  • Problem with hadoop start-dfs.sh

    - by user288501
    I installed and configured hadoop on my Ubuntu 14.04 server, virtualized inside of hyper-v, however I am getting an issue when i run start-dfs.sh root@sUbuntu01:/var/log# start-dfs.sh 14/06/04 15:27:08 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable Starting namenodes on [OpenJDK 64-Bit Server VM warning: You have loaded library /usr/local/hadoop/lib/native/libhadoop.so.1.0.0 which might have disabled stack guard. The VM will try to fix the stack guard now. It's highly recommended that you fix the library with 'execstack -c <libfile>', or link it with '-z noexecstack'. localhost] sed: -e expression #1, char 6: unknown option to `s' -c: Unknown cipher type 'cd' localhost: Ubuntu 14.04 LTS localhost: starting namenode, logging to /usr/local/hadoop/logs/hadoop-root-namenode-sUbuntu01.out noexecstack'.: ssh: Could not resolve hostname noexecstack'.: Name or service not known '-z: ssh: Could not resolve hostname '-z: Name or service not known 'execstack: ssh: Could not resolve hostname 'execstack: Name or service not known disabled: ssh: Could not resolve hostname disabled: Name or service not known with: ssh: Could not resolve hostname with: Name or service not known have: ssh: Could not resolve hostname have: Name or service not known VM: ssh: Could not resolve hostname vm: Name or service not known stack: ssh: Could not resolve hostname stack: Name or service not known guard: ssh: Could not resolve hostname guard: Name or service not known fix: ssh: Could not resolve hostname fix: Name or service not known VM: ssh: Could not resolve hostname vm: Name or service not known the: ssh: Could not resolve hostname the: Name or service not known to: ssh: Could not resolve hostname to: Name or service not known warning:: ssh: Could not resolve hostname warning:: Name or service not known it: ssh: Could not resolve hostname it: Name or service not known now.: ssh: Could not resolve hostname now.: Name or service not known library: ssh: Could not resolve hostname library: Name or service not known will: ssh: Could not resolve hostname will: Name or service not known link: ssh: Could not resolve hostname link: Name or service not known or: ssh: Could not resolve hostname or: Name or service not known It's: ssh: Could not resolve hostname it's: Name or service not known <libfile>',: ssh: Could not resolve hostname <libfile>',: Name or service not known which: ssh: connect to host which port 22: Connection timed out have: ssh: connect to host have port 22: Connection timed out you: ssh: connect to host you port 22: Connection timed out try: ssh: connect to host try port 22: Connection timed out the: ssh: connect to host the port 22: Connection timed out highly: ssh: connect to host highly port 22: Connection timed out might: ssh: connect to host might port 22: Connection timed out loaded: ssh: connect to host loaded port 22: Connection timed out You: ssh: connect to host you port 22: Connection timed out guard.: ssh: connect to host guard. port 22: Connection timed out library: ssh: connect to host library port 22: Connection timed out Server: ssh: connect to host server port 22: Connection timed out fix: ssh: connect to host fix port 22: Connection timed out The: ssh: connect to host the port 22: Connection timed out recommended: ssh: connect to host recommended port 22: Connection timed out that: ssh: connect to host that port 22: Connection timed out stack: ssh: connect to host stack port 22: Connection timed out OpenJDK: ssh: connect to host openjdk port 22: Connection timed out 64-Bit: ssh: connect to host 64-bit port 22: Connection timed out with: ssh: connect to host with port 22: Connection timed out localhost: Ubuntu 14.04 LTS localhost: starting datanode, logging to /usr/local/hadoop/logs/hadoop-root-datanode-sUbuntu01.out localhost: OpenJDK 64-Bit Server VM warning: You have loaded library /usr/local/hadoop/lib/native/libhadoop.so.1.0.0 which might have disabled stack guard. The VM will try to fix the stack guard now. localhost: It's highly recommended that you fix the library with 'execstack -c <libfile>', or link it with '-z noexecstack'. Starting secondary namenodes [OpenJDK 64-Bit Server VM warning: You have loaded library /usr/local/hadoop/lib/native/libhadoop.so.1.0.0 which might have disabled stack guard. The VM will try to fix the stack guard now. It's highly recommended that you fix the library with 'execstack -c <libfile>', or link it with '-z noexecstack'. 0.0.0.0] sed: -e expression #1, char 6: unknown option to `s' warning:: ssh: Could not resolve hostname warning:: Name or service not known -c: Unknown cipher type 'cd' It's: ssh: Could not resolve hostname it's: Name or service not known 'execstack: ssh: Could not resolve hostname 'execstack: Name or service not known '-z: ssh: Could not resolve hostname '-z: Name or service not known 0.0.0.0: Ubuntu 14.04 LTS 0.0.0.0: starting secondarynamenode, logging to /usr/local/hadoop/logs/hadoop-root-secondarynamenode-sUbuntu01.out 0.0.0.0: OpenJDK 64-Bit Server VM warning: You have loaded library /usr/local/hadoop/lib/native/libhadoop.so.1.0.0 which might have disabled stack guard. The VM will try to fix the stack guard now. 0.0.0.0: It's highly recommended that you fix the library with 'execstack -c <libfile>', or link it with '-z noexecstack'. noexecstack'.: ssh: Could not resolve hostname noexecstack'.: Name or service not known <libfile>',: ssh: Could not resolve hostname <libfile>',: Name or service not known link: ssh: Could not resolve hostname link: No address associated with hostname it: ssh: Could not resolve hostname it: No address associated with hostname to: ssh: connect to host to port 22: Connection timed out or: ssh: connect to host or port 22: Connection timed out you: ssh: connect to host you port 22: Connection timed out guard.: ssh: connect to host guard. port 22: Connection timed out VM: ssh: connect to host vm port 22: Connection timed out stack: ssh: connect to host stack port 22: Connection timed out library: ssh: connect to host library port 22: Connection timed out Server: ssh: connect to host server port 22: Connection timed out might: ssh: connect to host might port 22: Connection timed out stack: ssh: connect to host stack port 22: Connection timed out You: ssh: connect to host you port 22: Connection timed out now.: ssh: connect to host now. port 22: Connection timed out disabled: ssh: connect to host disabled port 22: Connection timed out have: ssh: connect to host have port 22: Connection timed out will: ssh: connect to host will port 22: Connection timed out The: ssh: connect to host the port 22: Connection timed out have: ssh: connect to host have port 22: Connection timed out try: ssh: connect to host try port 22: Connection timed out the: ssh: connect to host the port 22: Connection timed out guard: ssh: connect to host guard port 22: Connection timed out the: ssh: connect to host the port 22: Connection timed out recommended: ssh: connect to host recommended port 22: Connection timed out with: ssh: connect to host with port 22: Connection timed out library: ssh: connect to host library port 22: Connection timed out 64-Bit: ssh: connect to host 64-bit port 22: Connection timed out fix: ssh: connect to host fix port 22: Connection timed out which: ssh: connect to host which port 22: Connection timed out VM: ssh: connect to host vm port 22: Connection timed out OpenJDK: ssh: connect to host openjdk port 22: Connection timed out fix: ssh: connect to host fix port 22: Connection timed out highly: ssh: connect to host highly port 22: Connection timed out that: ssh: connect to host that port 22: Connection timed out with: ssh: connect to host with port 22: Connection timed out loaded: ssh: connect to host loaded port 22: Connection timed out 14/06/04 15:36:02 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable Any advice?

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  • Getting Started Building Windows 8 Store Apps with XAML/C#

    - by dwahlin
    Technology is fun isn’t it? As soon as you think you’ve figured out where things are heading a new technology comes onto the scene, changes things up, and offers new opportunities. One of the new technologies I’ve been spending quite a bit of time with lately is Windows 8 store applications. I posted my thoughts about Windows 8 during the BUILD conference in 2011 and still feel excited about the opportunity there. Time will tell how well it ends up being accepted by consumers but I’m hopeful that it’ll take off. I currently have two Windows 8 store application concepts I’m working on with one being built in XAML/C# and another in HTML/JavaScript. I really like that Microsoft supports both options since it caters to a variety of developers and makes it easy to get started regardless if you’re a desktop developer or Web developer. Here’s a quick look at how the technologies are organized in Windows 8: In this post I’ll focus on the basics of Windows 8 store XAML/C# apps by looking at features, files, and code provided by Visual Studio projects. To get started building these types of apps you’ll definitely need to have some knowledge of XAML and C#. Let’s get started by looking at the Windows 8 store project types available in Visual Studio 2012.   Windows 8 Store XAML/C# Project Types When you open Visual Studio 2012 you’ll see a new entry under C# named Windows Store. It includes 6 different project types as shown next.   The Blank App project provides initial starter code and a single page whereas the Grid App and Split App templates provide quite a bit more code as well as multiple pages for your application. The other projects available can be be used to create a class library project that runs in Windows 8 store apps, a WinRT component such as a custom control, and a unit test library project respectively. If you’re building an application that displays data in groups using the “tile” concept then the Grid App or Split App project templates are a good place to start. An example of the initial screens generated by each project is shown next: Grid App Split View App   When a user clicks a tile in a Grid App they can view details about the tile data. With a Split View app groups/categories are shown and when the user clicks on a group they can see a list of all the different items and then drill-down into them:   For the remainder of this post I’ll focus on functionality provided by the Blank App project since it provides a simple way to get started learning the fundamentals of building Windows 8 store apps.   Blank App Project Walkthrough The Blank App project is a great place to start since it’s simple and lets you focus on the basics. In this post I’ll focus on what it provides you out of the box and cover additional details in future posts. Once you have the basics down you can move to the other project types if you need the functionality they provide. The Blank App project template does exactly what it says – you get an empty project with a few starter files added to help get you going. This is a good option if you’ll be building an app that doesn’t fit into the grid layout view that you see a lot of Windows 8 store apps following (such as on the Windows 8 start screen). I ended up starting with the Blank App project template for the app I’m currently working on since I’m not displaying data/image tiles (something the Grid App project does well) or drilling down into lists of data (functionality that the Split App project provides). The Blank App project provides images for the tiles and splash screen (you’ll definitely want to change these), a StandardStyles.xaml resource dictionary that includes a lot of helpful styles such as buttons for the AppBar (a special type of menu in Windows 8 store apps), an App.xaml file, and the app’s main page which is named MainPage.xaml. It also adds a Package.appxmanifest that is used to define functionality that your app requires, app information used in the store, plus more. The App.xaml, App.xaml.cs and StandardStyles.xaml Files The App.xaml file handles loading a resource dictionary named StandardStyles.xaml which has several key styles used throughout the application: <Application x:Class="BlankApp.App" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:local="using:BlankApp"> <Application.Resources> <ResourceDictionary> <ResourceDictionary.MergedDictionaries> <!-- Styles that define common aspects of the platform look and feel Required by Visual Studio project and item templates --> <ResourceDictionary Source="Common/StandardStyles.xaml"/> </ResourceDictionary.MergedDictionaries> </ResourceDictionary> </Application.Resources> </Application>   StandardStyles.xaml has style definitions for different text styles and AppBar buttons. If you scroll down toward the middle of the file you’ll see that many AppBar button styles are included such as one for an edit icon. Button styles like this can be used to quickly and easily add icons/buttons into your application without having to be an expert in design. <Style x:Key="EditAppBarButtonStyle" TargetType="ButtonBase" BasedOn="{StaticResource AppBarButtonStyle}"> <Setter Property="AutomationProperties.AutomationId" Value="EditAppBarButton"/> <Setter Property="AutomationProperties.Name" Value="Edit"/> <Setter Property="Content" Value="&#xE104;"/> </Style> Switching over to App.xaml.cs, it includes some code to help get you started. An OnLaunched() method is added to handle creating a Frame that child pages such as MainPage.xaml can be loaded into. The Frame has the same overall purpose as the one found in WPF and Silverlight applications - it’s used to navigate between pages in an application. /// <summary> /// Invoked when the application is launched normally by the end user. Other entry points /// will be used when the application is launched to open a specific file, to display /// search results, and so forth. /// </summary> /// <param name="args">Details about the launch request and process.</param> protected override void OnLaunched(LaunchActivatedEventArgs args) { Frame rootFrame = Window.Current.Content as Frame; // Do not repeat app initialization when the Window already has content, // just ensure that the window is active if (rootFrame == null) { // Create a Frame to act as the navigation context and navigate to the first page rootFrame = new Frame(); if (args.PreviousExecutionState == ApplicationExecutionState.Terminated) { //TODO: Load state from previously suspended application } // Place the frame in the current Window Window.Current.Content = rootFrame; } if (rootFrame.Content == null) { // When the navigation stack isn't restored navigate to the first page, // configuring the new page by passing required information as a navigation // parameter if (!rootFrame.Navigate(typeof(MainPage), args.Arguments)) { throw new Exception("Failed to create initial page"); } } // Ensure the current window is active Window.Current.Activate(); }   Notice that in addition to creating a Frame the code also checks to see if the app was previously terminated so that you can load any state/data that the user may need when the app is launched again. If you’re new to the lifecycle of Windows 8 store apps the following image shows how an app can be running, suspended, and terminated.   If the user switches from an app they’re running the app will be suspended in memory. The app may stay suspended or may be terminated depending on how much memory the OS thinks it needs so it’s important to save state in case the application is ultimately terminated and has to be started fresh. Although I won’t cover saving application state here, additional information can be found at http://msdn.microsoft.com/en-us/library/windows/apps/xaml/hh465099.aspx. Another method in App.xaml.cs named OnSuspending() is also included in App.xaml.cs that can be used to store state as the user switches to another application:   /// <summary> /// Invoked when application execution is being suspended. Application state is saved /// without knowing whether the application will be terminated or resumed with the contents /// of memory still intact. /// </summary> /// <param name="sender">The source of the suspend request.</param> /// <param name="e">Details about the suspend request.</param> private void OnSuspending(object sender, SuspendingEventArgs e) { var deferral = e.SuspendingOperation.GetDeferral(); //TODO: Save application state and stop any background activity deferral.Complete(); } The MainPage.xaml and MainPage.xaml.cs Files The Blank App project adds a file named MainPage.xaml that acts as the initial screen for the application. It doesn’t include anything aside from an empty <Grid> XAML element in it. The code-behind class named MainPage.xaml.cs includes a constructor as well as a method named OnNavigatedTo() that is called once the page is displayed in the frame.   /// <summary> /// An empty page that can be used on its own or navigated to within a Frame. /// </summary> public sealed partial class MainPage : Page { public MainPage() { this.InitializeComponent(); } /// <summary> /// Invoked when this page is about to be displayed in a Frame. /// </summary> /// <param name="e">Event data that describes how this page was reached. The Parameter /// property is typically used to configure the page.</param> protected override void OnNavigatedTo(NavigationEventArgs e) { } }   If you’re experienced with XAML you can switch to Design mode and start dragging and dropping XAML controls from the ToolBox in Visual Studio. If you prefer to type XAML you can do that as well in the XAML editor or while in split mode. Many of the controls available in WPF and Silverlight are included such as Canvas, Grid, StackPanel, and Border for layout. Standard input controls are also included such as TextBox, CheckBox, PasswordBox, RadioButton, ComboBox, ListBox, and more. MediaElement is available for rendering video or playing audio files. Some of the “common” XAML controls included out of the box are shown next:   Although XAML/C# Windows 8 store apps don’t include all of the functionality available in Silverlight 5, the core functionality required to build store apps is there with additional functionality available in open source projects such as Callisto (started by Microsoft’s Tim Heuer), Q42.WinRT, and others. Standard XAML data binding can be used to bind C# objects to controls, converters can be used to manipulate data during the data binding process, and custom styles and templates can be applied to controls to modify them. Although Visual Studio 2012 doesn’t support visually creating styles or templates, Expression Blend 5 handles that very well. To get started building the initial screen of a Windows 8 app you can start adding controls as mentioned earlier. Simply place them inside of the <Grid> element that’s included. You can arrange controls in a stacked manner using the StackPanel control, add a border around controls using the Border control, arrange controls in columns and rows using the Grid control, or absolutely position controls using the Canvas control. One of the controls that may be new to you is the AppBar. It can be used to add menu/toolbar functionality into a store app and keep the app clean and focused. You can place an AppBar at the top or bottom of the screen. A user on a touch device can swipe up to display the bottom AppBar or right-click when using a mouse. An example of defining an AppBar that contains an Edit button is shown next. The EditAppBarButtonStyle is available in the StandardStyles.xaml file mentioned earlier. <Page.BottomAppBar> <AppBar x:Name="ApplicationAppBar" Padding="10,0,10,0" AutomationProperties.Name="Bottom App Bar"> <Grid> <StackPanel x:Name="RightPanel" Orientation="Horizontal" Grid.Column="1" HorizontalAlignment="Right"> <Button x:Name="Edit" Style="{StaticResource EditAppBarButtonStyle}" Tag="Edit" /> </StackPanel> </Grid> </AppBar> </Page.BottomAppBar> Like standard XAML controls, the <Button> control in the AppBar can be wired to an event handler method in the MainPage.Xaml.cs file or even bound to a ViewModel object using “commanding” if your app follows the Model-View-ViewModel (MVVM) pattern (check out the MVVM Light package available through NuGet if you’re using MVVM with Windows 8 store apps). The AppBar can be used to navigate to different screens, show and hide controls, display dialogs, show settings screens, and more.   The Package.appxmanifest File The Package.appxmanifest file contains configuration details about your Windows 8 store app. By double-clicking it in Visual Studio you can define the splash screen image, small and wide logo images used for tiles on the start screen, orientation information, and more. You can also define what capabilities the app has such as if it uses the Internet, supports geolocation functionality, requires a microphone or webcam, etc. App declarations such as background processes, file picker functionality, and sharing can also be defined Finally, information about how the app is packaged for deployment to the store can also be defined. Summary If you already have some experience working with XAML technologies you’ll find that getting started building Windows 8 applications is pretty straightforward. Many of the controls available in Silverlight and WPF are available making it easy to get started without having to relearn a lot of new technologies. In the next post in this series I’ll discuss additional features that can be used in your Windows 8 store apps.

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