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  • Mocking concrete class - Not recommended

    - by Mik378
    I've just read an excerpt of "Growing Object-Oriented Software" book which explains some reasons why mocking concrete class is not recommended. Here some sample code of a unit-test for the MusicCentre class: public class MusicCentreTest { @Test public void startsCdPlayerAtTimeRequested() { final MutableTime scheduledTime = new MutableTime(); CdPlayer player = new CdPlayer() { @Override public void scheduleToStartAt(Time startTime) { scheduledTime.set(startTime); } } MusicCentre centre = new MusicCentre(player); centre.startMediaAt(LATER); assertEquals(LATER, scheduledTime.get()); } } And his first explanation: The problem with this approach is that it leaves the relationship between the objects implicit. I hope we've made clear by now that the intention of Test-Driven Development with Mock Objects is to discover relationships between objects. If I subclass, there's nothing in the domain code to make such a relationship visible, just methods on an object. This makes it harder to see if the service that supports this relationship might be relevant elsewhere and I'll have to do the analysis again next time I work with the class. I can't figure out exactly what he means when he says: This makes it harder to see if the service that supports this relationship might be relevant elsewhere and I'll have to do the analysis again next time I work with the class. I understand that the service corresponds to MusicCentre's method called startMediaAt. What does he mean by "elsewhere"? The complete excerpt is here: http://www.mockobjects.com/2007/04/test-smell-mocking-concrete-classes.html

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  • What are the hard and fast rules for Cache Control?

    - by Metalshark
    Confession: sites I maintain have different rules for Cache Control mostly based on the default configuration of the server followed up with recommendations from the Page Speed & Y-Slow Firefox plug-ins and the Network Resources view in Google's Speed Tracer. Cache-Control is set to private/public depending on what they say to do, ETag's/Last-Modified headers are only tinkered with if Y-Slow suggests there is something wrong and Vary-Accept-Encoding seems necessary when manually gziping files for Amazon CloudFront. When reading through the material on the different options and what they do there seems to be conflicting information, rules for broken proxies and cargo cult configurations. Any of the official information provided by the analysis tools mentioned above is quite inaccessible as it deals with each topic individually instead of as a unified strategy (so there is no cross-referencing of techniques). For example, it seems to make no sense that the speed analysis tools rate a site with ETag's the same as a site without them if they are meant to help with caching. What are the hard and fast rules for a platform agnostic Cache Control strategy? EDIT: A link through Jeff Atwood's article explains Caching in superb depth. For the record though here are the hard and fast rules: If the file is Compressed using GZIP, etc - use "cache-control: private" as a proxy may return the compressed version to a client that does not support it (the browser cache will hold files marked this way though). Also remember to include a "Vary: Accept-Encoding" to say that it is compressible. Use Last-Modified in conjunction with ETag - belt and braces usage provides both validators, whilst ETag is based on file contents instead of modification time alone, using both covers all bases. NOTE: AOL's PageTest has a carte blanche approach against ETags for some reason. If you are using Apache on more than one server to host the same content then remove the implicitly declared inode from ETags by excluding it from the FileETag directive (i.e. "FileETag MTime Size") unless you are genuinely using the same live filesystem. Use "cache-control: public" wherever you can - this means that proxy servers (and the browser cache) will return your content even if the rest of the page needs HTTP authentication, etc.

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  • OSB, Service Callouts and OQL

    - by Sabha
    Oracle Fusion Middleware customers use Oracle Service Bus (OSB) for virtualizing Service endpoints and implementing stateless service orchestrations. Behind the performance and speed of OSB, there are a couple of key design implementations that can affect application performance and behavior under heavy load. One of the heavily used feature in OSB is the Service Callout pipeline action for message enrichment and invoking multiple services as part of one single orchestration. Overuse of this feature, without understanding its internal implementation, can lead to serious problems. This series will delve into OSB internals, the problem associated with usage of Service Callout under high loads, diagnosing it via thread dump and heap dump analysis using tools like ThreadLogic and OQL (Object Query Language) and resolving it. The first section in the series will mainly cover the threading model used internally by OSB for implementing Route Vs. Service Callouts. The second section of the "OSB, Service Callouts and OQL" blog posting will delve into thread dump analysis of OSB server and detecting threading issues relating to Service Callout and using Heap Dump and OQL to identify the related Proxies and Business services involved. The final section of the series will focus on the corrective action to avoid Service Callout related OSB serer hangs. Before we dive into the solution, we need to briefly discus about Work Managers in WLS. Please refer to the blog posting for more details.

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  • E-Bus ATG Advisor Webcast program - June Edition

    - by cwarticki
    E-Business Suite Applications Technology Group (ATG) Advisor Webcast Program – June 2014 Thursday June 12, 2014 at 18:00 UK / 10:00 PST / 11:00 MST / 13:00 EST EBS Patch Wizard Overview ·      What is Oracle EBS Patch Wizard Tool? ·      Benefits of the Patch Wizard utility ·      Patch Wizard Interface ·      Patch Impact Analysis Details & Registration : Note 1672371.1 Direct registration link Thursday June 26, 2014 at 18:00 UK / 10:00 PST / 11:00 MST / 13:00 EST EBS Proactive Analyzers Overview ·         What are Oracle Support Analyzers? ·         How to identify the Analyzers available? ·         Short Analyzers Overview ·         Patch Impact Analysis ·         How to use an Analyzer? Details & Registration : Note 1672363.1 Direct registration link If you have any question about the schedules or if you have a suggestion for an Advisor Webcast to be planned in future, please send an E-Mail to Ruediger Ziegler.

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  • C# class architecture for REST services

    - by user15370
    Hi. I am integrating with a set of REST services exposed by our partner. The unit of integration is at the project level meaning that for each project created on our partners side of the fence they will expose a unique set of REST services. To be more clear, assume there are two projects - project1 and project2. The REST services available to access the project data would then be: /project1/search/getstuff?etc... /project1/analysis/getstuff?etc... /project1/cluster/getstuff?etc... /project2/search/getstuff?etc... /project2/analysis/getstuff?etc... /project2/cluster/getstuff?etc... My task is to wrap these services in a C# class to be used by our app developer. I want to make it simple for the app developer and am thinking of providing something like the following class. class ProjectClient { SearchClient _searchclient; AnalysisClient _analysisclient; ClusterClient _clusterclient; string Project {get; set;} ProjectClient(string _project) { Project = _project; } } SearchClient, AnalysisClient and ClusterClient are my classes to support the respective services shown above. The problem with this approach is that ProjectClient will need to provide public methods for each of the API's exposed by SearchClient, etc... public void SearchGetStuff() { _searchclient.getStuff(); } Any suggestions how I can architect this better?

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  • Webmatrix The Site has Stopped Fix

    - by Tarun Arora
    I just got started with AzureWebSites by creating a website by choosing the Wordpress template. Next I tried to install WebMatrix so that I could run the website locally. Every time I tried to run my website from WebMatrix I hit the message “The following site has stopped ‘xxx’” Step 00 – Analysis It took a bit of time to figure out that WebMatrix makes use of IISExpress. But it was easy to figure out that IISExpress was not showing up in the system tray when I started WebMatrix. This was a good indication that IISExpress is having some trouble starting up. So, I opened CMD prompt and tried to run IISExpress.exe this resulted in the below error message So, I ran IISExpress.exe /trace:Error this gave more detailed reason for failure Step 1 – Fixing “The following site has stopped ‘xxx’” Further analysis revealed that the IIS Express config file had been corrupted. So, I navigated to C:\Users\<UserName>\Documents\IISExpress\config and deleted the files applicationhost.config, aspnet.config and redirection.config (please take a backup of these files before deleting them). Come back to CMD and run IISExpress /trace:Error IIS Express successfully started and parked itself in the system tray icon. I opened up WebMatrix and clicked Run, this time the default site successfully loaded up in the browser without any failures. Step 2 – Download WordPress Azure WebSite using WebMatrix Because the config files ‘applicationhost.config’, ‘aspnet.config’ and ‘redirection.config’ were deleted I lost the settings of my Azure based WordPress site that I had downloaded to run from WebMatrix. This was simple to sort out… Open up WebMatrix and go to the Remote tab, click on Download Export the PublishSettings file from Azure Management Portal and upload it on the pop up you get when you had clicked Download in the previous step Now you should have your Azure WordPress website all set up & running from WebMatrix. Enjoy!

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  • github team workflow - to fork or not?

    - by aporat
    We're a small team of web developers currently using subversion but soon we're making a switch to github. I'm looking at different types of github workflows, and we're not sure if the whole forking concept in github for each developer is such a good idea for us. If we use forks, I understand each developer will have his own private remote & local repositories. I'm worried it will make pushing changesets hard and too complex. Also, my biggest concern is that it will force each developer to have 2 remotes: origin (which is the remote fork) and an upstream (which is used to "sync" changes from the main repository). Not sure if it's such a easy way to do things. This is similar to the workflow explained here: https://github.com/usm-data-analysis/usm-data-analysis.github.com/wiki/Git-workflow If we don't use forks, we can probably get by fine by using a central repo creating a branch for each task we're working on, and merge them into the development branch on the same repository. It means we won't be able to restrict merging of branches and might be a little messy to have many branches on the central repository. Any suggestions from teams who tried both workflow?

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  • Smart Phones Shockingly Energy Efficient; Lead to Decreased Household Power Consumption

    - by Jason Fitzpatrick
    Given how often our smart phones and tablets spend plugged in and topping off their battery reserves, it’s easy to assume they’re sucking down a lot of power. Analysis shows the lilliputian but powerful devices are surprisingly efficient and may be decreasing our overall power consumption. Courtesy of energy-centric blog Outlier, we’re treated to a look at the power sipping habits of popular smart phones and mobile devices. The simple take away? They use shockingly little electricity over the course of the year–you can charge your new iPhone for a year of regular usage for under a buck. The more complex analysis? The proliferation of tiny and energy efficient devices is displacing heavier energy consumers (large televisions, desktop computers, etc.) and driving a more efficient gadget-to-consumption ratio is many households. Hit up the link below to read the full post. How Much Does It Take to Charge an iPhone [via Mashable] 7 Ways To Free Up Hard Disk Space On Windows HTG Explains: How System Restore Works in Windows HTG Explains: How Antivirus Software Works

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  • A Dozen USB Chargers Analyzed; Or: Beware the Knockoffs

    - by Jason Fitzpatrick
    When it comes to buying a USB charger one is just as good as another so you might as well buy the cheapest one, right? This interesting and detailed analysis of name brand, off-brand, and counterfeit chargers will have you rethinking that stance. Ken Shirriff gathered up a dozen USB chargers including official Apple chargers, counterfeit Apple chargers, as well as offerings from Monoprice, Belkin, Motorola, and other companies. After putting them all through a battery of tests he gave them overall rankings based on nine different categories including power stability, power quality, and efficiency. The take away from his research? Quality varied widely between brands but when sticking with big companies like Apple or HP the chargers were all safe. The counterfeit chargers (like the $2 Apple iPad charger knock-off he tested) proved to be outright dangerous–several actually melted or caught fire in the course of the project. Hit up the link below for his detailed analysis including power output readings for the dozen chargers. A Dozen USB Chargers in the Lab [via O'Reilly Radar] 6 Start Menu Replacements for Windows 8 What Is the Purpose of the “Do Not Cover This Hole” Hole on Hard Drives? How To Log Into The Desktop, Add a Start Menu, and Disable Hot Corners in Windows 8

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  • Spend Analytics on a Grand Scale

    - by jacqueline.coolidge(at)oracle.com
    The Wall St. Journal reports in Billions in Bloat Uncovered in Beltway that a recent study by Government Accountability Office (GAO) has released a massive study of several programs and agencies that cost U.S. taxpayers billions of dollars each year.  This report help save $100 to $200 Billion dollars by identifying duplicate spending and ineffective programs that can be consolidated or eliminated. Now, that is spend analytics on a massive scale! It remains to be seen how actionable that information will be.  Certainly, there have been studies before that identify wasteful spending.  But, it’s a great case of the power of business intelligence and spend analytics.   Many companies do find significant savings when they implement spend and procurement analytics. What makes for an excellent spend analysis? It should be: Objective and provide visibility across programs and/or divisions A cross functional analysis that links financial with performance metrics Prescriptive and actionable Spend and procurement analytics have been HOT during the economic downturn! I expect 2011 will see many more companies get serious about spend analytics and would love to hear from companies who are willing to share their experience.

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  • How to get full query string parameters not UrlDecoded

    - by developerit
    Introduction While developing Developer IT’s website, we came across a problem when the user search keywords containing special character like the plus ‘+’ char. We found it while looking for C++ in our search engine. The request parameter output in ASP.NET was “c “. I found it strange that it removed the ‘++’ and replaced it with a space… Analysis After a bit of Googling and Reflection, it turns out that ASP.NET calls UrlDecode on each parameters retreived by the Request(“item”) method. The Request.Params property is affected by this two since it mashes all QueryString, Forms and other collections into a single one. Workaround Finally, I solve the puzzle usign the Request.RawUrl property and parsing it with the same RegEx I use in my url re-writter. The RawUrl not affected by anything. As its name say it, it’s raw. Published on http://www.developerit.com/

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  • How do I install Revenge of the Titans?

    - by Akash
    I've downloaded the .deb file of Revenge of the Titans, and installed it using Ubuntu Software Center. Now, when I try to launch it using the software launcher nothing happens. Any ideas? The .deb file was downloaded from the Humble Indie Bundle. I am unable to launch it from the terminal ( the command revenge-of-the-titans says command not found ). I also tried the .tar.gz. When I extract it and run ./revenge.sh , nothing happens. No output on the terminal or anything at all. I have set chmod 777 revenge.sh as well. The command /opt/revengeofthetitans/revenge.sh does not give any output. If I run gedit /opt/revengeofthetitans/revenge.sh in the terminal: > #!/bin/bash > # > # revenge.sh > # > ############################################################################### > > SCRIPT="`basename $0`" > GAMEDIR="${HOME}/.revenge_of_the_titans_1.80" LOGFILE="${GAMEDIR}/${SCRIPT}.log" > INSTDIR="`dirname $0`" ; cd > "${INSTDIR}" ; INSTDIR="`pwd`" > > [[ ! -d "${GAMEDIR}" ]] && mkdir -m > 0755 "${GAMEDIR}" > > JARPATH="patch.jar:RevengeOfTheTitans.jar:data-hib.jar:gfx.jar:fonts.jar:images.jar:music.jar:fx-mono.jar:fx-stereo.jar:gamecommerce.jar:common.jar:spgl-lite.jar:lwjgl.jar:lwjgl_util.jar:jorbis.jar:jinput.jar" > > # XMODIFIERS is cleared here to prevent SCIM screwing up keyboard > input XMODIFIERS= java \ > -noverify \ > -Djava.library.path="${INSTDIR}" \ > -Dorg.lwjgl.util.NoChecks=true \ > -Dorg.lwjgl.librarypath="${INSTDIR}" \ > -Dnet.puppygames.applet.Launcher.resources=/resources-hib.dat > \ > -Dnet.puppygames.applet.Game.gameResource=game.hib > \ > -XX:MaxGCPauseMillis=3 \ > -Xms64m \ > -Xmx375m \ > -Xincgc \ > -cp "${JARPATH}" \ > net.puppygames.applet.Launcher \ > "$@" \ > >"${LOGFILE}" 2>&1 > > exit 0 > > # > # EOF > # > ###############################################################################

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  • C#/.NET: Process.HasExited returns true even though process is running??

    - by johnrl
    I have been observing that Process.HasExited sometimes returns true even though the process is still running. My code below starts a process with name "testprogram.exe" and then waits for it to exit. The problem is that sometimes I get thrown the exception; it seems that even though HasExited returns TRUE the process itself is still alive in the system - how can this be?? My program writes to a logfile just before it terminates and thus I need to be absolutely sure that this logfile exists (aka the process has terminated/finished) before reading it. Continuously checking for it's existence is not an option. // Create new process object process = new Process(); // Setup event handlers process.EnableRaisingEvents = true; process.OutputDataReceived += OutputDataReceivedEvent; process.ErrorDataReceived += ErrorDataReceivedEvent; process.Exited += ProgramExitedEvent; // Setup start info ProcessStartInfo psi = new ProcessStartInfo { FileName = ExePath, UseShellExecute = false, // Must be false to redirect IO RedirectStandardOutput = true, RedirectStandardError = true, Arguments = arguments }; process.StartInfo = psi; // Start the program process.Start(); while (!process.HasExited) Thread.Sleep( 500 ); Process[] p = Process.GetProcessesByName( "testprogram" ); if ( p.Length != 0 ) throw new Exception("Oh oh");

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  • How to make Nlog archive a file with the date when the logging took place.

    - by Carl Bergquist
    Hi, We are using Nlog as our logging framework and I cannot find a way to archive files the way I want. I would like to have the date of when the logging took place in the logging file name. Ex All logging that happend from 2009-10-01 00:00 -> 2009-10-01:23:59 should be placed in Log.2009-10-01.log The current NLog.config that I use looks like this. <?xml version="1.0" encoding="utf-8" ?> <nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" > <extensions> <add assembly="My.Awesome.LoggingExentions"/> </extensions> <targets> <target name="file1" xsi:type="File" fileName="${basedir}/Logs/Log.log" layout="${longdate} ${level:uppercase=true:padding=5} ${session} ${storeid} ${msisdn} - ${logger:shortName=true} - ${message} ${exception:format=tostring}" archiveEvery="Day" archiveFileName="${basedir}/Logs/Log${shortdate}-{#}.log" archiveNumbering="Sequence" maxArchiveFiles="99999" keepFileOpen="true" /> </targets> <rules> <logger name="*" minlevel="Trace" writeTo="file1" /> </rules> </nlog> This however sets the date in the logfile to the date when the new logfile is created. Which cause frustration when you want to read logs later. It also seems like I have to have atleast on # in the archiveFileName, which I rather not. So if you got a solution for that also I would be twice as thankful =)

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  • android logging sdcard

    - by Abhi Rao
    Hello, With Android-Emulator I am not able to write/create a file on the SD Card (for logging). Here is what I have done so far - Run mksdcard 8192K C:\android-dev\emu_sdcard\emu_logFile - Create a new AVD, when assign emu_logFile to it so that when I view the AVD Details it says C:\android-dev\emu_sdcard\emu_logFile against the field "SD Card" - Here is the relevant code public class ZLogger { static PrintWriter zLogWriter = null; private static void Initialize() { try { File sdDir = Environment.getExternalStorageDirectory(); if (sdDir.canWrite()) { : File logFile = new File (sdDir, VERSION.RELEASE + "_" + ".log"); FileWriter logFileWriter = new FileWriter(logFile); zLogWriter = new PrintWriter(logFileWriter); zLogWriter.write("\n\n - " + date + " - \n"); } } catch (IOException e) { Log.e("ZLogger", "Count not write to file: " + e.getMessage()); } } sdDir.canWrite returns false - please note it not the exception from adb shell when I do ls I see sdcard as link to /mnt/sdcard. When I do ls -l /mnt here is what I see ls -l /mnt ls -l /mnt drwxr-xr-x root system 2010-12-24 03:41 asec drwx------ root root 2010-12-24 03:41 secure d--------- system system 2010-12-24 03:41 sdcard whereas if I go to the directory where I created emu_sdcard - I see a lock has been issued, as shown here C:dir android-dev\emu_sdcard Volume in drive C is Preload Volume Serial Number is A4F3-6C29 Directory of C:\android-dev\emu_sdcard 12/24/2010 03:41 AM . 12/24/2010 03:41 AM .. 12/24/2010 03:17 AM 8,388,608 emu_logFile 12/24/2010 03:41 AM emu_logFile.lock 1 File(s) 8,388,608 bytes 3 Dir(s) 50,347,704,320 bytes free I have looked at these and other SO questions Android Emulator sdcard push error: Read-only file system (2) Not able to view SDCard folder in the FileExplorer of Android Eclipse I have added the following to AndroidManifest.xml **uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" ** Please let me know your thoughts - what am I missing here? Why does canWrite return false? What should I do to add permissions to sdcard?

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  • Why are my attempts to open a file using open for writing failing? Ada 95

    - by mat_geek
    When I attempt to open a file to write to I get an Ada.IO_Exceptions.Name_Error. The procedure call is Ada.Text_IO.Open The file name is "C:\CC_TEST_LOG.TXT". This file does not exist. This is on Windows XP on an NTFS partition. The user has permissions to create and write to the directory. The filename is well under the WIN32 max path length. name_2 : String := "C:\CC_TEST_LOG.TXT" if name_2'last > name_2'first then begin Ada.Text_IO.Open(file, Ada.Text_IO.Out_File, name_2); Ada.Text_IO.Put_Line( "CC_Test_Utils: LogFile: ERROR: Open, File " & name_2); return; exception when The_Error : others => Ada.Text_IO.Put_Line( "CC_Test_Utils: LogFile: ERROR: Open Failed; " & Ada.Exceptions.Exception_Name(The_Error) & ", File " & name_2); end; end if;

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  • log4net creates log file but does not write to it (windows service in C#)

    - by user1825172
    I am trying to use basic logging for a windows service. I added the reference to log4net I added the following in AssemblyInfo.cs: [assembly: log4net.Config.XmlConfigurator(Watch = true)] I added the following to my App.config: <?xml version="1.0" encoding="utf-8" ?> <configuration> <configSections> <section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler,log4net, Version=1.2.10.0, Culture=neutral, PublicKeyToken=1b44e1d426115821" requirePermission="false" /> </configSections> <!-- Log4net Logging Setup --> <log4net> <appender name="RollingFileAppender" type="log4net.Appender.RollingFileAppender,log4net"> <file value="c:\\CGSD\\log\\logfile.txt" /> <appendToFile value="true" /> <lockingModel type="log4net.Appender.FileAppender+MinimalLock" /> <layout type="log4net.Layout.PatternLayout"> <conversionPattern value="%date [%thread] %level %logger - %message%newline" /> </layout> <filter type="log4net.Filter.LevelRangeFilter"> <levelMin value="INFO" /> <levelMax value="FATAL" /> </filter> </appender> <root> <level value="ALL"/> <appender-ref ref="RollingFileAppender"/> </root> </log4net> </configuration> I have the following code in my service: log4net.Config.XmlConfigurator.Configure(); log4net.ILog log = log4net.LogManager.GetLogger(typeof(Program)); log.Debug("test"); the file c:\CGSD\log\logfile.txt is created but nothing is ever written to it. i've been thru the forums all day trying to trac this one down, but if i overlooked an already posted solution i apologize. thx!

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  • Cocoa: Using UNIX based commands to write a file

    - by BryCry
    I'm looking for help with a program im making. I create a *.sh file as follows: SVN_StatGenAppDelegate.h: NSWindow *window; NSTask *touch; NSArray *touchArguments; NSString *svnURLStr; NSString *SVNStatStr; NSString *destDirStr; SVN_StatGenApplDelegate.m: NSString *locationStr = [NSString stringWithFormat:@"%@/exec.sh", destDirStr]; NSLog(@"%@", locationStr); touch = [[NSTask alloc] init]; [touch setLaunchPath:@"/usr/bin/touch"]; touchArguments = [NSArray arrayWithObjects:locationStr, nil]; [touch setArguments:touchArguments]; [touch launch]; This works, i get a file called exec.sh created in the location i craete with the destDirStr. Now is my next question, i need to get that file filled with the following: svn co http://repo.com/svn/test C:\users\twan\desktop\pres\_temp cd C:\users\twan\desktop\pres\_temp svn log -v --xml > logfile.log copy C:\users\twan\desktop\statsvn.jar C:\users\twan\desktop\pres\_temp cd .. java -jar _temp\statsvn.jar C:\users\twan\desktop\pres\_temp/logfile.log C:\users\twan\desktop\pres\_temp rmdir /s /Q _temp The actual idea is that this script is written into the sh file, and all the _temp and other locations are replaced by the vars i get from textfields etc. so c:\users\twan\desktop\pres_temp would be a var called tempDirStr that i get from my inputfields. (i know these cmomands and locations are windows based, im doing this with a friend and he made a .net counterpart of the application. Can you guys help me out?:D thanks in advance!

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  • Your thoughts on Best Practices for Scientific Computing?

    - by John Smith
    A recent paper by Wilson et al (2014) pointed out 24 Best Practices for scientific programming. It's worth to have a look. I would like to hear opinions about these points from experienced programmers in scientific data analysis. Do you think these advices are helpful and practical? Or are they good only in an ideal world? Wilson G, Aruliah DA, Brown CT, Chue Hong NP, Davis M, Guy RT, Haddock SHD, Huff KD, Mitchell IM, Plumbley MD, Waugh B, White EP, Wilson P (2014) Best Practices for Scientific Computing. PLoS Biol 12:e1001745. http://www.plosbiology.org/article/info%3Adoi%2F10.1371%2Fjournal.pbio.1001745 Box 1. Summary of Best Practices Write programs for people, not computers. (a) A program should not require its readers to hold more than a handful of facts in memory at once. (b) Make names consistent, distinctive, and meaningful. (c) Make code style and formatting consistent. Let the computer do the work. (a) Make the computer repeat tasks. (b) Save recent commands in a file for re-use. (c) Use a build tool to automate workflows. Make incremental changes. (a) Work in small steps with frequent feedback and course correction. (b) Use a version control system. (c) Put everything that has been created manually in version control. Don’t repeat yourself (or others). (a) Every piece of data must have a single authoritative representation in the system. (b) Modularize code rather than copying and pasting. (c) Re-use code instead of rewriting it. Plan for mistakes. (a) Add assertions to programs to check their operation. (b) Use an off-the-shelf unit testing library. (c) Turn bugs into test cases. (d) Use a symbolic debugger. Optimize software only after it works correctly. (a) Use a profiler to identify bottlenecks. (b) Write code in the highest-level language possible. Document design and purpose, not mechanics. (a) Document interfaces and reasons, not implementations. (b) Refactor code in preference to explaining how it works. (c) Embed the documentation for a piece of software in that software. Collaborate. (a) Use pre-merge code reviews. (b) Use pair programming when bringing someone new up to speed and when tackling particularly tricky problems. (c) Use an issue tracking tool. I'm relatively new to serious programming for scientific data analysis. When I tried to write code for pilot analyses of some of my data last year, I encountered tremendous amount of bugs both in my code and data. Bugs and errors had been around me all the time, but this time it was somewhat overwhelming. I managed to crunch the numbers at last, but I thought I couldn't put up with this mess any longer. Some actions must be taken. Without a sophisticated guide like the article above, I started to adopt "defensive style" of programming since then. A book titled "The Art of Readable Code" helped me a lot. I deployed meticulous input validations or assertions for every function, renamed a lot of variables and functions for better readability, and extracted many subroutines as reusable functions. Recently, I introduced Git and SourceTree for version control. At the moment, because my co-workers are much more reluctant about these issues, the collaboration practices (8a,b,c) have not been introduced. Actually, as the authors admitted, because all of these practices take some amount of time and effort to introduce, it may be generally hard to persuade your reluctant collaborators to comply them. I think I'm asking your opinions because I still suffer from many bugs despite all my effort on many of these practices. Bug fix may be, or should be, faster than before, but I couldn't really measure the improvement. Moreover, much of my time has been invested on defence, meaning that I haven't actually done much data analysis (offence) these days. Where is the point I should stop at in terms of productivity? I've already deployed: 1a,b,c, 2a, 3a,b,c, 4b,c, 5a,d, 6a,b, 7a,7b I'm about to have a go at: 5b,c Not yet: 2b,c, 4a, 7c, 8a,b,c (I could not really see the advantage of using GNU make (2c) for my purpose. Could anyone tell me how it helps my work with MATLAB?)

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  • Introducing Microsoft SQL Server 2008 R2 - Business Intelligence Samples

    - by smisner
    On April 14, 2010, Microsoft Press (blog | twitter) released my latest book, co-authored with Ross Mistry (twitter), as a free ebook download - Introducing Microsoft SQL Server 2008 R2. As the title implies, this ebook is an introduction to the latest SQL Server release. Although you'll find a comprehensive review of the product's features in this book, you will not find the step-by-step details that are typical in my other books. For those readers who are interested in a more interactive learning experience, I have created two samples file for download: IntroSQLServer2008R2Samples project Sales Analysis workbook Here's a recap of the business intelligence chapters and the samples I used to generate the screen shots by chapter: Chapter 6: Scalable Data Warehousing covers a new edition of SQL Server, Parallel Data Warehouse. Understandably, Microsoft did not ship me the software and hardware to set up my own Parallel Data Warehouse environment for testing purposes and consequently you won't see any screenshots in this chapter. I received a lot of information and a lot of help from the product team during the development of this chapter to ensure its technical accuracy. Chapter 7: Master Data Services is a new component in SQL Server. After you install Master Data Services (MDS), which is a separate installation from SQL Server although it's found on the same media, you can install sample models to explore (which is what I did to create screenshots for the book). To do this, you deploying packages found at \Program Files\Microsoft SQL Server\Master Data Services\Samples\Packages. You will first need to use the Configuration Manager (in the Microsoft SQL Server 2008 R2\Master Data Services program group) to create a database and a Web application for MDS. Then when you launch the application, you'll see a Getting Started page which has a Deploy Sample Data link that you can use to deploy any of the sample packages. Chapter 8: Complex Event Processing is an introduction to another new component, StreamInsight. This topic was way too large to cover in-depth in a single chapter, so I focused on information such as architecture, development models, and an overview of the key sections of code you'll need to develop for your own applications. StreamInsight is an engine that operates on data in-flight and as such has no user interface that I could include in the book as screenshots. The November CTP version of SQL Server 2008 R2 included code samples as part of the installation, but these are not the official samples that will eventually be available in Codeplex. At the time of this writing, the samples are not yet published. Chapter 9: Reporting Services Enhancements provides an overview of all the changes to Reporting Services in SQL Server 2008 R2, and there are many! In previous posts, I shared more details than you'll find in the book about new functions (Lookup, MultiLookup, and LookupSet), properties for page numbering, and the new global variable RenderFormat. I will confess that I didn't use actual data in the book for my discussion on the Lookup functions, but I did create real reports for the blog posts and will upload those separately. For the other screenshots and examples in the book, I have created the IntroSQLServer2008R2Samples project for you to download. To preview these reports in Business Intelligence Development Studio, you must have the AdventureWorksDW2008R2 database installed, and you must download and install SQL Server 2008 R2. For the map report, you must execute the PopulationData.sql script that I included in the samples file to add a table to the AdventureWorksDW2008R2 database. The IntroSQLServer2008R2Samples project includes the following files: 01_AggregateOfAggregates.rdl to illustrate the use of embedded aggregate functions 02_RenderFormatAndPaging.rdl to illustrate the use of page break properties (Disabled, ResetPageNumber), the PageName property, and the RenderFormat global variable 03_DataSynchronization.rdl to illustrate the use of the DomainScope property 04_TextboxOrientation.rdl to illustrate the use of the WritingMode property 05_DataBar.rdl 06_Sparklines.rdl 07_Indicators.rdl 08_Map.rdl to illustrate a simple analytical map that uses color to show population counts by state PopulationData.sql to provide the data necessary for the map report Chapter 10: Self-Service Analysis with PowerPivot introduces two new components to the Microsoft BI stack, PowerPivot for Excel and PowerPivot for SharePoint, which you can learn more about at the PowerPivot site. To produce the screenshots for this chapter, I created the Sales Analysis workbook which you can download (although you must have Excel 2010 and the PowerPivot for Excel add-in installed to explore it fully). It's a rather simple workbook because space in the book did not permit a complete exploration of all the wonderful things you can do with PowerPivot. I used a tutorial that was available with the CTP version as a basis for the report so it might look familiar if you've already started learning about PowerPivot. In future posts, I'll continue exploring the new features in greater detail. If there's any special requests, please let me know! Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

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  • SQL SERVER – Example of Performance Tuning for Advanced Users with DB Optimizer

    - by Pinal Dave
    Performance tuning is such a subject that everyone wants to master it. In beginning everybody is at a novice level and spend lots of time learning how to master the art of performance tuning. However, as we progress further the tuning of the system keeps on getting very difficult. I have understood in my early career there should be no need of ego in the technology field. There are always better solutions and better ideas out there and we should not resist them. Instead of resisting the change and new wave I personally adopt it. Here is a similar example, as I personally progress to the master level of performance tuning, I face that it is getting harder to come up with optimal solutions. In such scenarios I rely on various tools to teach me how I can do things better. Once I learn about tools, I am often able to come up with better solutions when I face the similar situation next time. A few days ago I had received a query where the user wanted to tune it further to get the maximum out of the performance. I have re-written the similar query with the help of AdventureWorks sample database. SELECT * FROM HumanResources.Employee e INNER JOIN HumanResources.EmployeeDepartmentHistory edh ON e.BusinessEntityID = edh.BusinessEntityID INNER JOIN HumanResources.Shift s ON edh.ShiftID = s.ShiftID; User had similar query to above query was used in very critical report and wanted to get best out of the query. When I looked at the query – here were my initial thoughts Use only column in the select statements as much as you want in the application Let us look at the query pattern and data workload and find out the optimal index for it Before I give further solutions I was told by the user that they need all the columns from all the tables and creating index was not allowed in their system. He can only re-write queries or use hints to further tune this query. Now I was in the constraint box – I believe * was not a great idea but if they wanted all the columns, I believe we can’t do much besides using *. Additionally, if I cannot create a further index, I must come up with some creative way to write this query. I personally do not like to use hints in my application but there are cases when hints work out magically and gives optimal solutions. Finally, I decided to use Embarcadero’s DB Optimizer. It is a fantastic tool and very helpful when it is about performance tuning. I have previously explained how it works over here. First open DBOptimizer and open Tuning Job from File >> New >> Tuning Job. Once you open DBOptimizer Tuning Job follow the various steps indicates in the following diagram. Essentially we will take our original script and will paste that into Step 1: New SQL Text and right after that we will enable Step 2 for Generating Various cases, Step 3 for Detailed Analysis and Step 4 for Executing each generated case. Finally we will click on Analysis in Step 5 which will generate the report detailed analysis in the result pan. The detailed pan looks like. It generates various cases of T-SQL based on the original query. It applies various hints and available hints to the query and generate various execution plans of the query and displays them in the resultant. You can clearly notice that original query had a cost of 0.0841 and logical reads about 607 pages. Whereas various options which are just following it has different execution cost as well logical read. There are few cases where we have higher logical read and there are few cases where as we have very low logical read. If we pay attention the very next row to original query have Merge_Join_Query in description and have lowest execution cost value of 0.044 and have lowest Logical Reads of 29. This row contains the query which is the most optimal re-write of the original query. Let us double click over it. Here is the query: SELECT * FROM HumanResources.Employee e INNER JOIN HumanResources.EmployeeDepartmentHistory edh ON e.BusinessEntityID = edh.BusinessEntityID INNER JOIN HumanResources.Shift s ON edh.ShiftID = s.ShiftID OPTION (MERGE JOIN) If you notice above query have additional hint of Merge Join. With the help of this Merge Join query hint this query is now performing much better than before. The entire process takes less than 60 seconds. Please note that it the join hint Merge Join was optimal for this query but it is not necessary that the same hint will be helpful in all the queries. Additionally, if the workload or data pattern changes the query hint of merge join may be no more optimal join. In that case, we will have to redo the entire exercise once again. This is the reason I do not like to use hints in my queries and I discourage all of my users to use the same. However, if you look at this example, this is a great case where hints are optimizing the performance of the query. It is humanly not possible to test out various query hints and index options with the query to figure out which is the most optimal solution. Sometimes, we need to depend on the efficiency tools like DB Optimizer to guide us the way and select the best option from the suggestion provided. Let me know what you think of this article as well your experience with DB Optimizer. Please leave a comment. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Joins, SQL Optimization, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • Code Metrics: Number of IL Instructions

    - by DigiMortal
    In my previous posting about code metrics I introduced how to measure LoC (Lines of Code) in .NET applications. Now let’s take a step further and let’s take a look how to measure compiled code. This way we can somehow have a picture about what compiler produces. In this posting I will introduce you code metric called number of IL instructions. NB! Number of IL instructions is not something you can use to measure productivity of your team. If you want to get better idea about the context of this metric and LoC then please read my first posting about LoC. What are IL instructions? When code written in some .NET Framework language is compiled then compiler produces assemblies that contain byte code. These assemblies are executed later by Common Language Runtime (CLR) that is code execution engine of .NET Framework. The byte code is called Intermediate Language (IL) – this is more common language than C# and VB.NET by example. You can use ILDasm tool to convert assemblies to IL assembler so you can read them. As IL instructions are building blocks of all .NET Framework binary code these instructions are smaller and highly general – we don’t want very rich low level language because it executes slower than more general language. For every method or property call in some .NET Framework language corresponds set of IL instructions. There is no 1:1 relationship between line in high level language and line in IL assembler. There are more IL instructions than lines in C# code by example. How much instructions there are? I have no common answer because it really depends on your code. Here you can see some metrics from my current community project that is developed on SharePoint Server 2007. As average I have about 7 IL instructions per line of code. This is not metric you should use, it is just illustrative example so you can see the differences between numbers of lines and IL instructions. Why should I measure the number of IL instructions? Just take a look at chart above. Compiler does something that you cannot see – it compiles your code to IL. This is not intuitive process because you usually cannot say what is exactly the end result. You know it at greater plain but you don’t know it exactly. Therefore we can expect some surprises and that’s why we should measure the number of IL instructions. By example, you may find better solution for some method in your source code. It looks nice, it works nice and everything seems to be okay. But on server under load your fix may be way slower than previous code. Although you minimized the number of lines of code it ended up with increasing the number of IL instructions. How to measure the number of IL instructions? My choice is NDepend because Visual Studio is not able to measure this metric. Steps to make are easy. Open your NDepend project or create new and add all your application assemblies to project (you can also add Visual Studio solution to project). Run project analysis and wait until it is done. You can see over-all stats form global summary window. This is the same window I used to read the LoC and the number of IL instructions metrics for my chart. Meanwhile I made some changes to my code (enabled advanced caching for events and event registrations module) and then I ran code analysis again to get results for this section of this posting. NDepend is also able to tell you exactly what parts of code have problematically much IL instructions. The code quality section of CQL Query Explorer shows you how much problems there are with members in analyzed code. If you click on the line Methods too big (NbILInstructions) you can see all the problematic members of classes in CQL Explorer shown in image on right. In my case if have 10 methods that are too big and two of them have horrible number of IL instructions – just take a look at first two methods in this TOP10. Also note the query box. NDepend has easy and SQL-like query language to query code analysis results. You can modify these queries if you like and also you can define your own ones if default set is not enough for you. What is good result? As you can see from query window then the number of IL instructions per member should have maximally 200 IL instructions. Of course, like always, the less instructions you have, the better performing code you have. I don’t mean here little differences but big ones. By example, take a look at my first method in warnings list. The number of IL instructions it has is huge. And believe me – this method looks awful. Conclusion The number of IL instructions is useful metric when optimizing your code. For analyzing code at general level to find out too long methods you can use the number of LoC metric because it is more intuitive for you and you can therefore handle the situation more easily. Also you can use NDepend as code metrics tool because it has a lot of metrics to offer.

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  • ORA-7445 Troubleshooting

    - by [email protected]
        QUICKLINK: Note 153788.1 ORA-600/ORA-7445 Lookup tool Note 1082674.1 : A Video To Demonstrate The Usage Of The ORA-600/ORA-7445 Lookup Tool [Video]   Have you observed an ORA-07445 error reported in your alert log? While the ORA-600 error is "captured" as a handled exception in the Oracle source code, the ORA-7445 is an unhandled exception error due to an OS exception which should result in the creation of a core file.  An ORA-7445 is a generic error, and can occur from anywhere in the Oracle code. The precise location of the error is identified by the core file and/or trace file it produces.  Looking for the best way to diagnose? Whenever an ORA-7445 error is raised a core file is generated.  There may be a trace file generated with the error as well.   Prior to 11g, the core files are located in the CORE_DUMP_DEST directory.   Starting with 11g, there is a new advanced fault diagnosability infrastructure to manage trace data.  Diagnostic files are written into a root directory for all diagnostic data called the ADR home.   Core files at 11g will go to the ADR HOME/cdump directory.   For more information on the Oracle 11g Diagnosability feature see Note 453125.1 11g Diagnosability Frequently Asked Questions Note 443529.1 11g Quick Steps to Package and Send Critical Error Diagnostic Information to Support[Video]   NOTE:  While the core file is captured in the Diagnosability infrastructure, the file may not be included with a diagnostic package.1.  Check the Alert LogThe alert log may indicate additional errors or other internal errors at the time of the problem.   In some cases, the ORA-7445 error will occur along with ORA-600, ORA-3113, ORA-4030 errors.  The ORA-7445 error can be side effects of the other problems and you should review the first error and associated core file or trace file and work down the list of errors.   Note 1020463.6 DIAGNOSING ORA-3113 ERRORS Note 1812.1 TECH:  Getting a Stack Trace from a CORE file Note 414966.1 RDA Documentation Index   If the ORA-7445 errors are not associated with other error conditions, ensure the trace data is not truncated. If you see a message at the end of the file   "MAX DUMP FILE SIZE EXCEEDED"   the MAX_DUMP_FILE_SIZE parameter is not setup high enough or to 'unlimited'. There could be vital diagnostic information missing in the file and discovering the root issue may be very difficult.  Set the MAX_DUMP_FILE_SIZE appropriately and regenerate the error for complete trace information. For pointers on deeper analysis of these errors see   Note 390293.1 Introduction to 600/7445 Internal Error Analysis Note 211909.1 Customer Introduction to ORA-7445 Errors 2.  Search 600/7445 Lookup Tool Visit My Oracle Support to access the ORA-00600 Lookup tool (Note 153788.1). The ORA-600/ORA-7445 Lookup tool may lead you to applicable content in My Oracle Support on the problem and can be used to investigate the problem with argument data from the error message or you can pull out key stack pointers from the associated trace file to match up against known bugs.3.  "Fine tune" searches in Knowledge Base As the ORA-7445 error indicates an unhandled exception in the Oracle source code, your search in the Oracle Knowledge Base will need to focus on the stack data from the core file or the trace file. Keep in mind that searches on generic argument data will bring back a large result set.  The more you can learn about the environment and code leading to the errors, the easier it will be to narrow the hit list to match your problem. Note 153788.1 ORA-600/ORA-7445 TroubleshooterNote 1082674.1 A Video To Demonstrate The Usage Of The ORA-600/ORA-7445 Lookup Tool [Video] NOTE:  If no trace file is captured, see Note 1812.1 TECH:  Getting a Stack Trace from a CORE file.  Core files are managed through 11g Diagnosability, but are not packaged with other diagnostic data automatically.  The core files can be quite large, but may be useful during analysis within Oracle Support.4.  If assistance is required from Oracle Should it become necessary to get assistance from Oracle Support on an ORA-7445 problem, please provide at a minimum, the Alert log  Associated tracefile(s) or incident package at 11g Patch level  information Core file(s)  Information about changes in configuration and/or application prior to  issues  If error is reproducible, a self-contained reproducible testcase: Note.232963.1 How to Build a Testcase for Oracle Data Server Support to Reproduce ORA-600 and ORA-7445 Errors RDA report or Oracle Configuration Manager information Oracle Configuration Manager Quick Start Guide Note 548815.1 My Oracle Support Configuration Management FAQ Note 414966.1 RDA Documentation Index ***For reference to the content in this blog, refer to Note.1092832.1 Master Note for Diagnosing ORA-600

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  • Oracle WebCenter at the Enterprise 2.0 Conference

    - by Brian Dirking
    We had a great week at the E20 Conference, presenting in four sessions – Andy MacMillan gave a session titled Today’s Successful Enterprises are Social Enterprises and was on a panel that Tony Byrne moderated; Christian Finn spoke on a panel on Unified Communications Unified Communications + Social Computing = Best of Both Worlds?, Mark Bennett spoke on a panel on The Evolution of Talent Management. The key areas of focus this year were sentiment analysis, adoption and community building, the benefits of failure, and social’s role in process applications. Sentiment analysis. This was focused not on external audiences but more on employee sentiment. Tim Young showed his internal "NikoNiko" project, where employees use smilies to report their current mood. The result was a dashboard that showed the company mood by department. Since the goal is to improve productivity, people can see which departments are running into issues and try and address them. A company might otherwise wait until the end of the quarter financials to find out that there was a problem and product didn’t ship. This is a way to identify issues immediately. Tim is great – he had the crowd laughing as soon as he hit the stage, with his proposed hastag for his session: by making it 138 characters long, people couldn’t say much behind his back. And as I tweeted during his session, I loved his comment that complexity diffuses energy - it sounds like something Sun Tzu would say. Another example of employee sentiment analysis was CubeVibe. Founder and CEO Aaron Aycock, in his 3 minute pitch or die session talked about how engaged employees perform better. It was too bad he got gonged, he was just picking up speed, but CubeVibe did win the vote – congratulations to them. Internal adoption, community building, and involvement. On this topic I spoke to Terri Griffith, and she said there is some good work going on at University of Indiana regarding this, and hinted that she might be blogging about it in the near future. This area holds lots of interest for me. Amongst our customers, - CPAC stands out as an organization that has successfully built a community. So, I wonder - what are the building blocks? A strong leader? A common or unifying purpose? A certain level of engagement? I imagine someone has created an equation that says “for a community to grow at 30% per month, there must be an engagement level x to the square root of y, where x equals current community size, and y equals the expected growth rate, and the result is how many engagements the average user must contribute to maintain that growth.” Does anyone have a framework like that? The net result of everyone’s experience is that there is nothing to do but start early and fail often. Kevin Jones made this the focus of his keynote. He talked about the types of failure and what they mean. And he showed his famous kids at work video: Kevin’s blog also has this post: Social Business Failure #8: Workflow Integration. This is something that we’ve been working on at Oracle. Since so much of business is based in enterprise applications such as ERP and CRM (and since Oracle offers e-Business Suite, Siebel, PeopleSoft, and JD Edwards, as well as Fusion Applications), it makes sense that the social capabilities of Oracle WebCenter is built right into these applications. There are two types of social collaboration – ad-hoc, and exception handling. When you are in a business process and encounter an exception, you immediately look for 1) the document that tells you how to handle it, or 2) the person who can tell you how to handle it. With WebCenter built into these processes, people either search their content management system, or engage in expertise location and conversation. The great thing is, THEY DON’T HAVE TO LEAVE THE APPLICATION TO DO IT. Oracle has built the social capabilities right into the applications and business processes. I don’t think enough folks were able to see that at the event, but I expect that over the next six months folks will become very aware of it. WebCenter also provides the ability to have ad-hoc collaboration, search, and expertise location that folks need when they are innovating or collaborating. We demonstrated Oracle Social Network. It’s built on our Oracle WebCenter product to provide social collaboration inside and outside of your company. When we showed it to people, there were a number of areas that they commented on that were different from the other products being shown at the conference: Screenshots from within the product Many authors working on documents simultaneously Flagging people for follow up Direct ability to call out to people Ability to see presence not just if someone is online, but which conversation they are actively in Great stuff, the conference was full of smart people that that we enjoy spending time with. We’ll keep up in the meantime, but we look forward to seeing you in Boston.

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  • Goto for the Java Programming Language

    - by darcy
    Work on JDK 8 is well-underway, but we thought this late-breaking JEP for another language change for the platform couldn't wait another day before being published. Title: Goto for the Java Programming Language Author: Joseph D. Darcy Organization: Oracle. Created: 2012/04/01 Type: Feature State: Funded Exposure: Open Component: core/lang Scope: SE JSR: 901 MR Discussion: compiler dash dev at openjdk dot java dot net Start: 2012/Q2 Effort: XS Duration: S Template: 1.0 Reviewed-by: Duke Endorsed-by: Edsger Dijkstra Funded-by: Blue Sun Corporation Summary Provide the benefits of the time-testing goto control structure to Java programs. The Java language has a history of adding new control structures over time, the assert statement in 1.4, the enhanced for-loop in 1.5,and try-with-resources in 7. Having support for goto is long-overdue and simple to implement since the JVM already has goto instructions. Success Metrics The goto statement will allow inefficient and verbose recursive algorithms and explicit loops to be replaced with more compact code. The effort will be a success if at least twenty five percent of the JDK's explicit loops are replaced with goto's. Coordination with IDE vendors is expected to help facilitate this goal. Motivation The goto construct offers numerous benefits to the Java platform, from increased expressiveness, to more compact code, to providing new programming paradigms to appeal to a broader demographic. In JDK 8, there is a renewed focus on using the Java platform on embedded devices with more modest resources than desktop or server environments. In such contexts, static and dynamic memory footprint is a concern. One significant component of footprint is the code attribute of class files and certain classes of important algorithms can be expressed more compactly using goto than using other constructs, saving footprint. For example, to implement state machines recursively, some parties have asked for the JVM to support tail calls, that is, to perform a complex transformation with security implications to turn a method call into a goto. Such complicated machinery should not be assumed for an embedded context. A better solution is just to expose to the programmer the desired functionality, goto. The web has familiarized users with a model of traversing links among different HTML pages in a free-form fashion with some state being maintained on the side, such as login credentials, to effect behavior. This is exactly the programming model of goto and code. While in the past this has been derided as leading to "spaghetti code," spaghetti is a tasty and nutritious meal for programmers, unlike quiche. The invokedynamic instruction added by JSR 292 exposes the JVM's linkage operation to programmers. This is a low-level operation that can be leveraged by sophisticated programmers. Likewise, goto is a also a low-level operation that should not be hidden from programmers who can use more efficient idioms. Some may object that goto was consciously excluded from the original design of Java as one of the removed feature from C and C++. However, the designers of the Java programming languages have revisited these removals before. The enum construct was also left out only to be added in JDK 5 and multiple inheritance was left out, only to be added back by the virtual extension method methods of Project Lambda. As a living language, the needs of the growing Java community today should be used to judge what features are needed in the platform tomorrow; the language should not be forever bound by the decisions of the past. Description From its initial version, the JVM has had two instructions for unconditional transfer of control within a method, goto (0xa7) and goto_w (0xc8). The goto_w instruction is used for larger jumps. All versions of the Java language have supported labeled statements; however, only the break and continue statements were able to specify a particular label as a target with the onerous restriction that the label must be lexically enclosing. The grammar addition for the goto statement is: GotoStatement: goto Identifier ; The new goto statement similar to break except that the target label can be anywhere inside the method and the identifier is mandatory. The compiler simply translates the goto statement into one of the JVM goto instructions targeting the right offset in the method. Therefore, adding the goto statement to the platform is only a small effort since existing compiler and JVM functionality is reused. Other language changes to support goto include obvious updates to definite assignment analysis, reachability analysis, and exception analysis. Possible future extensions include a computed goto as found in gcc, which would replace the identifier in the goto statement with an expression having the type of a label. Testing Since goto will be implemented using largely existing facilities, only light levels of testing are needed. Impact Compatibility: Since goto is already a keyword, there are no source compatibility implications. Performance/scalability: Performance will improve with more compact code. JVMs already need to handle irreducible flow graphs since goto is a VM instruction.

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