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  • Techniques to prevent non-official clients in network gaming?

    - by UpTheCreek
    In multi-player network games, what techniques exist to try to ensure that users are connecting with the official client application, and not some hacked client app? I realise there is probably no sure-fire way to do this, but rather I'm interested in techniques that can be employed to mitigate the problem. I'm especially interested in any techniques that can be used for web based games, but I imagine most can be applied generally. Thank you!

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  • The open-source entrepreneur

    <b>BBC News: </b>"Bob Young is a self-confessed contrarian with a strong desire to change the world by allowing people to share and collaborate. The approach has served him well and has helped turn the Canadian into a multi-millionaire."

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  • DevCamp Azure : l'évènement de Microsoft disponible en replay pour ceux qui ont loupé le live du 1er juillet

    DevCamp Azure : l'évènement de Microsoft disponible en replay Pour ceux qui ont loupé le live du 1er juilletVous avez loupé l'évènement 100 % en ligne autour de Windows Azure organisé par Microsot ce lundi ?Bonne nouvelle : un replay de ce « DevCamp » sur la plateforme Cloud pour les développeurs est disponible depuis aujourd'hui. Vous retrouverez les 8 sessions de 30 minutes sur des thèmes aussi variés que la BI en mode Cloud (avec SharePoint), la gestion d'identité dans Azure et Office365, l'administration d'une infrastructure Cloud hybride, le Big Data ou les Backend pour les applis multi...

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  • Init Replication From Backup

    One of the great features with SQL Replication is the ability to initialize a subscription from backup instead of from a snapshot. The official use for this is to take a database backup and restore it to a subscriber then replicate any additional changes to the backup. New! SQL Monitor 3.0 Red Gate's multi-server performance monitoring and alerting tool gets results from Day One.Simple to install and easy to use – download a free trial today.

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  • Steps to Apply a Service Pack or Patch to Mirrored SQL Server Databases

    Planning on patching my SQL Servers to the latest service pack, but not sure how to complete this for a environment that is using database mirroring? In this tip, will outline the environment and then walk through the process of patching mirrored servers. New! SQL Monitor 3.0 Red Gate's multi-server performance monitoring and alerting tool gets results from Day One.Simple to install and easy to use – download a free trial today.

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  • Development of Text Editor Teditor 1.5

    This application is adapted to viewing text files, it can carry out also creation of new files and editing of existing files. It allows the user to enter the name of a created or opened file. The user can scroll the text in a multi-line text component then there are seen other areas of the text.

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  • Development of Text Editor Teditor 1.5

    This application is adapted to viewing text files, it can carry out also creation of new files and editing of existing files. It allows the user to enter the name of a created or opened file. The user can scroll the text in a multi-line text component then there are seen other areas of the text.

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  • Why hasn't C# gained much traction within the opensource community?

    - by tmitchel2
    I'm not expecting C# to be on par with say Java or Python in the open source community, but it still surprises me just how far behind it is. 'Multi language' open source repos like google code or github have barely any C# projects in comparison to the other languages I mentioned. I'd like to see C# and .Net shake off that slight corporate feel and move more into the open source arena but I just can't see that happening. I'd be interested to hear peoples opinion on why this might be?

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  • GNOME 2.30 has been released

    <b>LWN.net:</b> "Today, the GNOME Project celebrates the release of GNOME 2.30, the latest version of the popular, multi-platform free desktop environment and of its developer platform."

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  • System.Web.Services.Protocols.SoapException - Security perssmission issue

    - by Hiscal
    Can any one help me to resolve this error.My website hosted on shared environment. Server Error in '/' Application. System.Web.Services.Protocols.SoapException: Server was unable to process request. ---> System.Security.SecurityException: Request for the permission of type 'System.Security.Permissions.SecurityPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' failed. at System.Security.CodeAccessSecurityEngine.Check(Object demand, StackCrawlMark& stackMark, Boolean isPermSet) at System.Security.CodeAccessPermission.Demand() at System.Net.ServicePointManager.set_CertificatePolicy(ICertificatePolicy value) at BirdieThis.WebService.golfService.BookGolfCourse(CourseBooking oCourseInfo, CoursePlayer oCoursePlayer, CoursePayment oCoursePayment) The action that failed was: Demand The type of the first permission that failed was: System.Security.Permissions.SecurityPermission The first permission that failed was: <IPermission class="System.Security.Permissions.SecurityPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Flags="UnmanagedCode"/> The demand was for: <IPermission class="System.Security.Permissions.SecurityPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Flags="UnmanagedCode"/> The granted set of the failing assembly was: <PermissionSet class="System.Security.PermissionSet" version="1"> <IPermission class="System.Security.Permissions.EnvironmentPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Read="TEMP;TMP;USERNAME;OS;COMPUTERNAME"/> <IPermission class="System.Security.Permissions.FileIOPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Read="D:\Hosting\5457055\html" Write="d:\content\;d:\hosting\" Append="D:\Hosting\5457055\html" PathDiscovery="d:\hosting\"/> <IPermission class="System.Security.Permissions.IsolatedStorageFilePermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Allowed="AssemblyIsolationByUser" UserQuota="9223372036854775807"/> <IPermission class="System.Security.Permissions.ReflectionPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Flags="RestrictedMemberAccess"/> <IPermission class="System.Security.Permissions.SecurityPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Flags="Assertion, Execution, ControlThread, ControlPrincipal, RemotingConfiguration"/> <IPermission class="System.Security.Permissions.UrlIdentityPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Url="file:///D:/Hosting/5457055/html/bin/App_Code.DLL"/> <IPermission class="System.Security.Permissions.ZoneIdentityPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Zone="MyComputer"/> <IPermission class="System.Security.Permissions.KeyContainerPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Unrestricted="true"/> <IPermission class="System.Web.AspNetHostingPermission, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Level="Medium"/> <IPermission class="System.Configuration.ConfigurationPermission, System.Configuration, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" version="1" Unrestricted="true"/> <IPermission class="System.Net.DnsPermission, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Unrestricted="true"/> <IPermission class="System.Drawing.Printing.PrintingPermission, System.Drawing, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" version="1" Level="DefaultPrinting"/> <IPermission class="System.Net.Mail.SmtpPermission, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Access="Connect"/> <IPermission class="System.Data.SqlClient.SqlClientPermission, System.Data, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Unrestricted="true"/> <IPermission class="System.Data.OleDb.OleDbPermission, System.Data, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Unrestricted="true"/> <IPermission class="System.Data.Odbc.OdbcPermission, System.Data, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Unrestricted="true"/> <IPermission class="System.Net.WebPermission, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1"> <ConnectAccess> <URI uri="http://.*"/> <URI uri="https://.*"/> </ConnectAccess> </IPermission> <IPermission class="System.Net.SocketPermission, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1"> <ConnectAccess> <ENDPOINT host="*.*.*.*" transport="Tcp" port="3306"/> </ConnectAccess> </IPermission> </PermissionSet> The assembly or AppDomain that failed was: App_Code, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null The method that caused the failure was: golfswitchs.BookGolfResult BookGolfCourse(mygolf.CourseBooking, mygolf.CoursePlayer, mygolf.CoursePayment) The Zone of the assembly that failed was: MyComputer The Url of the assembly that failed was: file:///D:/Hosting/5457055/html/bin/App_Code.DLL --- End of inner exception stack trace --- Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.Web.Services.Protocols.SoapException: System.Web.Services.Protocols.SoapException: Server was unable to process request. ---> System.Security.SecurityException: Request for the permission of type 'System.Security.Permissions.SecurityPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' failed. at System.Security.CodeAccessSecurityEngine.Check(Object demand, StackCrawlMark& stackMark, Boolean isPermSet) at System.Security.CodeAccessPermission.Demand() at System.Net.ServicePointManager.set_CertificatePolicy(ICertificatePolicy value) at BirdieThis.WebService.golfService.BookGolfCourse(CourseBooking oCourseInfo, CoursePlayer oCoursePlayer, CoursePayment oCoursePayment) The action that failed was: Demand The type of the first permission that failed was: System.Security.Permissions.SecurityPermission The first permission that failed was: <IPermission class="System.Security.Permissions.SecurityPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Flags="UnmanagedCode"/> The demand was for: <IPermission class="System.Security.Permissions.SecurityPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Flags="UnmanagedCode"/> The granted set of the failing assembly was: <PermissionSet class="System.Security.PermissionSet" version="1"> <IPermission class="System.Security.Permissions.EnvironmentPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Read="TEMP;TMP;USERNAME;OS;COMPUTERNAME"/> <IPermission class="System.Security.Permissions.FileIOPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Read="D:\Hosting\5457055\html" Write="d:\content\;d:\hosting\" Append="D:\Hosting\5457055\html" PathDiscovery="d:\hosting\"/> <IPermission class="System.Security.Permissions.IsolatedStorageFilePermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Allowed="AssemblyIsolationByUser" UserQuota="9223372036854775807"/> <IPermission class="System.Security.Permissions.ReflectionPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Flags="RestrictedMemberAccess"/> <IPermission class="System.Security.Permissions.SecurityPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Flags="Assertion, Execution, ControlThread, ControlPrincipal, RemotingConfiguration"/> <IPermission class="System.Security.Permissions.UrlIdentityPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Url="file:///D:/Hosting/5457055/html/bin/App_Code.DLL"/> <IPermission class="System.Security.Permissions.ZoneIdentityPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Zone="MyComputer"/> <IPermission class="System.Security.Permissions.KeyContainerPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Unrestricted="true"/> <IPermission class="System.Web.AspNetHostingPermission, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Level="Medium"/> <IPermission class="System.Configuration.ConfigurationPermission, System.Configuration, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" version="1" Unrestricted="true"/> <IPermission class="System.Net.DnsPermission, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Unrestricted="true"/> <IPermission class="System.Drawing.Printing.PrintingPermission, System.Drawing, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" version="1" Level="DefaultPrinting"/> <IPermission class="System.Net.Mail.SmtpPermission, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Access="Connect"/> <IPermission class="System.Data.SqlClient.SqlClientPermission, System.Data, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Unrestricted="true"/> <IPermission class="System.Data.OleDb.OleDbPermission, System.Data, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Unrestricted="true"/> <IPermission class="System.Data.Odbc.OdbcPermission, System.Data, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Unrestricted="true"/> <IPermission class="System.Net.WebPermission, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1"> <ConnectAccess> <URI uri="http://.*"/> <URI uri="https://.*"/> </ConnectAccess> </IPermission> <IPermission class="System.Net.SocketPermission, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1"> <ConnectAccess> <ENDPOINT host="*.*.*.*" transport="Tcp" port="3306"/> </ConnectAccess> </IPermission> </PermissionSet> The assembly or AppDomain that failed was: App_Code, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null The method that caused the failure was: golfswitchs.BookGolfResult BookGolfCourse(mygolf.CourseBooking, mygolf.CoursePlayer, mygolf.CoursePayment) The Zone of the assembly that failed was: MyComputer The Url of the assembly that failed was: file:///D:/Hosting/5457055/html/bin/App_Code.DLL --- End of inner exception stack trace --- Source Error: Line 446: Line 447: oPayment.PayCurrency = "USD"; Line 448: oResult = oService.BookGolfCourse(oGolfItem, oGolfplayer, oPayment); Line 449: Response.Write(oResult.RetMsg); Line 450: Source File: c:\inetpub\vhosts\cfmdeveloper.com\subdomains\ind103\httpdocs\test.aspx.cs Line: 448 Stack Trace: [SoapException: System.Web.Services.Protocols.SoapException: Server was unable to process request. ---> System.Security.SecurityException: Request for the permission of type 'System.Security.Permissions.SecurityPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' failed. at System.Security.CodeAccessSecurityEngine.Check(Object demand, StackCrawlMark& stackMark, Boolean isPermSet) at System.Security.CodeAccessPermission.Demand() at System.Net.ServicePointManager.set_CertificatePolicy(ICertificatePolicy value) at BirdieThis.WebService.golfService.BookGolfCourse(CourseBooking oCourseInfo, CoursePlayer oCoursePlayer, CoursePayment oCoursePayment) The action that failed was: Demand The type of the first permission that failed was: System.Security.Permissions.SecurityPermission The first permission that failed was: <IPermission class="System.Security.Permissions.SecurityPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Flags="UnmanagedCode"/> The demand was for: <IPermission class="System.Security.Permissions.SecurityPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Flags="UnmanagedCode"/> The granted set of the failing assembly was: <PermissionSet class="System.Security.PermissionSet" version="1"> <IPermission class="System.Security.Permissions.EnvironmentPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Read="TEMP;TMP;USERNAME;OS;COMPUTERNAME"/> <IPermission class="System.Security.Permissions.FileIOPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Read="D:\Hosting\5457055\html" Write="d:\content\;d:\hosting\" Append="D:\Hosting\5457055\html" PathDiscovery="d:\hosting\"/> <IPermission class="System.Security.Permissions.IsolatedStorageFilePermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Allowed="AssemblyIsolationByUser" UserQuota="9223372036854775807"/> <IPermission class="System.Security.Permissions.ReflectionPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Flags="RestrictedMemberAccess"/> <IPermission class="System.Security.Permissions.SecurityPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Flags="Assertion, Execution, ControlThread, ControlPrincipal, RemotingConfiguration"/> <IPermission class="System.Security.Permissions.UrlIdentityPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Url="file:///D:/Hosting/5457055/html/bin/App_Code.DLL"/> <IPermission class="System.Security.Permissions.ZoneIdentityPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Zone="MyComputer"/> <IPermission class="System.Security.Permissions.KeyContainerPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Unrestricted="true"/> <IPermission class="System.Web.AspNetHostingPermission, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Level="Medium"/> <IPermission class="System.Configuration.ConfigurationPermission, System.Configuration, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" version="1" Unrestricted="true"/> <IPermission class="System.Net.DnsPermission, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Unrestricted="true"/> <IPermission class="System.Drawing.Printing.PrintingPermission, System.Drawing, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" version="1" Level="DefaultPrinting"/> <IPermission class="System.Net.Mail.SmtpPermission, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Access="Connect"/> <IPermission class="System.Data.SqlClient.SqlClientPermission, System.Data, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Unrestricted="true"/> <IPermission class="System.Data.OleDb.OleDbPermission, System.Data, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Unrestricted="true"/> <IPermission class="System.Data.Odbc.OdbcPermission, System.Data, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Unrestricted="true"/> <IPermission class="System.Net.WebPermission, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1"> <ConnectAccess> <URI uri="http://.*"/> <URI uri="https://.*"/> </ConnectAccess> </IPermission> <IPermission class="System.Net.SocketPermission, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1"> <ConnectAccess> <ENDPOINT host="*.*.*.*" transport="Tcp" port="3306"/> </ConnectAccess> </IPermission> </PermissionSet> The assembly or AppDomain that failed was: App_Code, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null The method that caused the failure was: golfswitchs.BookGolfResult BookGolfCourse(mygolf.CourseBooking, mygolf.CoursePlayer, mygolf.CoursePayment) The Zone of the assembly that failed was: MyComputer The Url of the assembly that failed was: file:///D:/Hosting/5457055/html/bin/App_Code.DLL --- End of inner exception stack trace ---] System.Web.Services.Protocols.SoapHttpClientProtocol.ReadResponse(SoapClientMessage message, WebResponse response, Stream responseStream, Boolean asyncCall) +431766 System.Web.Services.Protocols.SoapHttpClientProtocol.Invoke(String methodName, Object[] parameters) +204 mygolf.golfService.BookGolfCourse(CourseBooking oCourseInfo, CoursePlayer oCoursePlayer, CoursePayment oCoursePayment) +80 birdiethis.web.test.BookClub() in c:\inetpub\vhosts\cfmdeveloper.com\subdomains\ind103\httpdocs\test.aspx.cs:448 birdiethis.web.test.Page_Load(Object sender, EventArgs e) in c:\inetpub\vhosts\cfmdeveloper.com\subdomains\ind103\httpdocs\test.aspx.cs:28 System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e) +14 System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) +35 System.Web.UI.Control.OnLoad(EventArgs e) +99 System.Web.UI.Control.LoadRecursive() +50 System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +627 Version Information: Microsoft .NET Framework Version:2.0.50727.3603; ASP.NET Version:2.0.50727.3082

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  • The Challenge with HTML5 – In Pictures

    - by dwahlin
    I love working with Web technologies and am looking forward to the new functionality that HTML5 will ultimately bring to the table (some of which can be used today). Having been through the div versus layer battle back in the IE4 and Netscape 4 days I think we’re headed down that road again as a result of browsers implementing features differently. I’ve been spending a lot of time researching and playing around with HTML5 samples and features (mainly because we’re already seeing demand for training on HTML5) and there’s a lot of great stuff there that will truly revolutionize web applications as we know them. However, browsers just aren’t there yet and many people outside of the development world don’t really feel a need to upgrade their browser if it’s working reasonably well (Mom and Dad come to mind) so it’s going to be awhile. There’s a nice test site at http://www.HTML5Test.com that runs through different HTML5 features and scores how well they’re supported. They don’t test for everything and are very clear about that on the site: “The HTML5 test score is only an indication of how well your browser supports the upcoming HTML5 standard and related specifications. It does not try to test all of the new features offered by HTML5, nor does it try to test the functionality of each feature it does detect. Despite these shortcomings we hope that by quantifying the level of support users and web developers will get an idea of how hard the browser manufacturers work on improving their browsers and the web as a development platform. The score is calculated by testing for the many new features of HTML5. Each feature is worth one or more points. Apart from the main HTML5 specification and other specifications created the W3C HTML Working Group, this test also awards points for supporting related drafts and specifications. Some of these specifications were initially part of HTML5, but are now further developed by other W3C working groups. WebGL is also part of this test despite not being developed by the W3C, because it extends the HTML5 canvas element with a 3d context. The test also awards bonus points for supporting audio and video codecs and supporting SVG or MathML embedding in a plain HTML document. These test do not count towards the total score because HTML5 does not specify any required audio or video codec. Also SVG and MathML are not required by HTML5, the specification only specifies rules for how such content should be embedded inside a plain HTML file. Please be aware that the specifications that are being tested are still in development and could change before receiving an official status. In the future new tests will be added for the pieces of the specification that are currently still missing. The maximum number of points that can be scored is 300 at this moment, but this is a moving goalpost.” It looks like their tests haven’t been updated since June, but the numbers are pretty scary as a developer because it means I’m going to have to do a lot of browser sniffing before assuming a particular feature is available to use. Not that much different from what we do today as far as browser sniffing you say? I’d have to disagree since HTML5 takes it to a whole new level. In today’s world we have script libraries such as jQuery (my personal favorite), Prototype, script.aculo.us, YUI Library, MooTools, etc. that handle the heavy lifting for us. Until those libraries handle all of the key HTML5 features available it’s going to be a challenge. Certain features such as Canvas are supported fairly well across most of the major browsers while other features such as audio and video are hit or miss depending upon what codec you want to use. Run the tests yourself to see what passes and what fails for different browsers. You can also view the HTML5 Test Suite Conformance Results at http://test.w3.org/html/tests/reporting/report.htm (a work in progress). The table below lists the scores that the HTML5Test site returned for different browsers I have installed on my desktop PC and laptop. A specific list of tests run and features supported are given when you go to the site. Note that I went ahead and tested the IE9 beta and it didn’t do nearly as good as I expected it would, but it’s not officially out yet so I expect that number will change a lot. Am I opposed to HTML5 as a result of these tests? Of course not - I’m actually really excited about what it offers.  However, I’m trying to be realistic and feel it'll definitely add a new level of headache to the Web application development process having been through something like this many years ago. On the flipside, developers that are able to target a specific browser (typically Intranet apps) or master the cross-browser issues are going to release some pretty sweet applications. Check out http://html5gallery.com/ for a look at some of the more cutting-edge sites out there that use HTML5. Also check out the http://www.beautyoftheweb.com site that Microsoft put together to showcase IE9. Chrome 8 Safari 5 for Windows     Opera 10 Firefox 3.6     Internet Explorer 9 Beta (Note that it’s still beta) Internet Explorer 8

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  • New Product: Oracle Java ME Embedded 3.2 – Small, Smart, Connected

    - by terrencebarr
    The Internet of Things (IoT) is coming. And, with todays launch of the Oracle Java ME Embedded 3.2 product, Java is going to play an even greater role in it. Java in the Internet of Things By all accounts, intelligent embedded devices are penetrating the world around us – driving industrial processes, monitoring environmental conditions, providing better health care, analyzing and processing data, and much more. And these devices are becoming increasingly connected, adding another dimension of utility. Welcome to the Internet of Things. As I blogged yesterday, this is a huge opportunity for the Java technology and ecosystem. To enable and utilize these billions of devices effectively you need a programming model, tools, and protocols which provide a feature-rich, consistent, scalable, manageable, and interoperable platform.  Java technology is ideally suited to address these technical and business problems, enabling you eliminate many of the typical challenges in designing embedded solutions. By using Java you can focus on building smarter, more valuable embedded solutions faster. To wit, Java technology is already powering around 10 billion devices worldwide. Delivering on this vision and accelerating the growth of embedded Java solutions, Oracle is today announcing a brand-new product: Oracle Java Micro Edition (ME) Embedded 3.2, accompanied by an update release of the Java ME Software Development Kit (SDK) to version 3.2. What is Oracle Java ME Embedded 3.2? Oracle Java ME Embedded 3.2 is a complete Java runtime client, optimized for ARM architecture connected microcontrollers and other resource-constrained systems. The product provides dedicated embedded functionality and is targeted for low-power, limited memory devices requiring support for a range of network services and I/O interfaces.  What features and APIs are provided by Oracle Java ME Embedded 3.2? Oracle Java ME Embedded 3.2 is a Java ME runtime based on CLDC 1.1 (JSR-139) and IMP-NG (JSR-228). The runtime and virtual machine (VM) are highly optimized for embedded use. Also included in the product are the following optional JSRs and Oracle APIs: File I/O API’s (JSR-75)  Wireless Messaging API’s (JSR-120) Web Services (JSR-172) Security and Trust Services subset (JSR-177) Location API’s (JSR-179) XML API’s (JSR-280)  Device Access API Application Management System (AMS) API AccessPoint API Logging API Additional embedded features are: Remote application management system Support for continuous 24×7 operation Application monitoring, auto-start, and system recovery Application access to peripheral interfaces such as GPIO, I2C, SPIO, memory mapped I/O Application level logging framework, including option for remote logging Headless on-device debugging – source level Java application debugging over IP Connection Remote configuration of the Java VM What type of platforms are targeted by Oracle Java ME 3.2 Embedded? The product is designed for embedded, always-on, resource-constrained, headless (no graphics/no UI), connected (wired or wireless) devices with a variety of peripheral I/O.  The high-level system requirements are as follows: System based on ARM architecture SOCs Memory footprint (approximate) from 130 KB RAM/350KB ROM (for a minimal, customized configuration) to 700 KB RAM/1500 KB ROM (for the full, standard configuration)  Very simple embedded kernel, or a more capable embedded OS/RTOS At least one type of network connection (wired or wireless) The initial release of the product is delivered as a device emulation environment for x86/Windows desktop computers, integrated with the Java ME SDK 3.2. A standard binary of Oracle Java ME Embedded 3.2 for ARM KEIL development boards based on ARM Cortex M-3/4 (KEIL MCBSTM32F200 using ST Micro SOC STM32F207IG) will soon be available for download from the Oracle Technology Network (OTN).  What types of applications can I develop with Oracle Java ME Embedded 3.2? The Oracle Java ME Embedded 3.2 product is a full-featured embedded Java runtime supporting applications based on the IMP-NG application model, which is derived from the well-known MIDP 2 application model. The runtime supports execution of multiple concurrent applications, remote application management, versatile connectivity, and a rich set of APIs and features relevant for embedded use cases, including the ability to interact with peripheral I/O directly from Java applications. This rich feature set, coupled with familiar and best-in class software development tools, allows developers to quickly build and deploy sophisticated embedded solutions for a wide range of use cases. Target markets well supported by Oracle Java ME Embedded 3.2 include wireless modules for M2M, industrial and building control, smart grid infrastructure, home automation, and environmental sensors and tracking. What tools are available for embedded application development for Oracle Java ME Embedded 3.2? Along with the release of Oracle Java ME Embedded 3.2, Oracle is also making available an updated version of the Java ME Software Development Kit (SDK), together with plug-ins for the NetBeans and Eclipse IDEs, to deliver a complete development environment for embedded application development.  OK – sounds great! Where can I find out more? And how do I get started? There is a complete set of information, data sheet, API documentation, “Getting Started Guide”, FAQ, and download links available: For an overview of Oracle Embeddable Java, see here. For the Oracle Java ME Embedded 3.2 press release, see here. For the Oracle Java ME Embedded 3.2 data sheet, see here. For the Oracle Java ME Embedded 3.2 landing page, see here. For the Oracle Java ME Embedded 3.2 documentation page, including a “Getting Started Guide” and FAQ, see here. For the Oracle Java ME SDK 3.2 landing and download page, see here. Finally, to ask more questions, please see the OTN “Java ME Embedded” forum To get started, grab the “Getting Started Guide” and download the Java ME SDK 3.2, which includes the Oracle Java ME Embedded 3.2 device emulation.  Can I learn more about Oracle Java ME Embedded 3.2 at JavaOne and/or Java Embedded @ JavaOne? Glad you asked Both conferences, JavaOne and Java Embedded @ JavaOne, will feature a host of content and information around the new Oracle Java ME Embedded 3.2 product, from technical and business sessions, to hands-on tutorials, and demos. Stay tuned, I will post details shortly. Cheers, – Terrence Filed under: Mobile & Embedded Tagged: "Oracle Java ME Embedded", Connected, embedded, Embedded Java, Java Embedded @ JavaOne, JavaOne, Smart

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  • Tweaking a few URL validation settings on ASP.NET v4.0

    - by Carlyle Dacosta
    ASP.NET has a few default settings for URLs out of the box. These can be configured quite easily in the web.config file within the  <system.web>/<httpRuntime> configuration section. Some of these are: <httpRuntime maxUrlLength=”<number here>”. This number should be an integer value (defaults to 260 characters). The value must be greater than or equal to zero, though obviously small values will lead to an un-useable website. This attribute gates the length of the Url without query string. <httpRuntime maxQueryStringLength=”<number here>”. This number should be an integer value (defaults to 2048 characters). The value must be greater than or equal to zero, though obviously small values will lead to an un-useable website. <httpRuntime requestPathInvalidCharacters=”List of characters you need included in ASP.NETs validation checks”. By default the characters are “<,>,*,%,&,:,\,?”. However once can easily change this by setting by modifying web.config. Remember, these characters can be specified in a variety of formats. For example, I want the character ‘!’ to be included in ASP.NETs URL validation logic. So I set the following: <httpRuntime requestPathInvalidCharacters=”<,>,*,%,&,:,\,?,!”. A character could also be specified in its xml encoded form. ‘&lt;;’ would mean the ‘<’ sign). I could specify the ‘!’ in its xml encoded unicode format such as requestPathInvalidCharacters=”<,>,*,%,&,:,\,?,$#x0021;” or I could specify it in its unicode encoded form or in the “<,>,*,%,&,:,\,?,%u0021” format. The following settings can be applied at Root Web.Config level, App Web.config level, Folder level or within a location tag: <location path="some path here"> <system.web> <httpRuntime maxUrlLength="" maxQueryStringLength="" requestPathInvalidChars="" .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } If any of the above settings fail request validation, an Http 400 “Bad Request” HttpException is thrown. These can be easily handled on the Application_Error handler on Global.asax.   Also, a new attribute in <httpRuntime /> called “relaxedUrlToFileSystemMapping” has been added with a default of false. <httpRuntime … relaxedUrlToFileSystemMapping="true|false" /> When the relaxedUrlToFileSystemMapping attribute is set to false inbound Urls still need to be valid NTFS file paths. For example Urls (sans query string) need to be less than 260 characters; no path segment within a Url can use old-style DOS device names (LPT1, COM1, etc…); Urls must be valid Windows file paths. A url like “http://digg.com/http://cnn.com” should work with this attribute set to true (of course a few characters will need to be unblocked by removing them from requestPathInvalidCharacters="" above). Managed configuration for non-NTFS-compliant Urls is determined from the first valid configuration path found when walking up the path segments of the Url. For example, if the request Url is "/foo/bar/baz/<blah>data</blah>", and there is a web.config in the "/foo/bar" directory, then the managed configuration for the request comes from merging the configuration hierarchy to include the web.config from "/foo/bar". The value of the public property HttpRequest.PhysicalPath is set to [physical file path of the application root] + "REQUEST_URL_IS_NOT_A_VALID_FILESYSTEM_PATH". For example, given a request Url like "/foo/bar/baz/<blah>data</blah>", where the application root is "/foo/bar" and the physical file path for that root is "c:\inetpub\wwwroot\foo\bar", then PhysicalPath would be "c:\inetpub\wwwroot\foo\bar\ REQUEST_URL_IS_NOT_A_VALID_FILESYSTEM_PATH". Carl Dacosta ASP.NET QA Team

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  • Feedback on "market manipulation", a peripheral game mechanic for a satirical MMO

    - by BerndBrot
    This question asks for feedback on a specific game-mechanic. Since there is not one right feedback on a game mechanic, I tried to provide enough context and guidelines to still make it possible for users to rate answers and to accept an answer as the best answer (following these criteria from Writer.SE's meta website). Please comment if you have any suggestions on how I could improve the question in that regard. So, let's begin with the game itself and some of its elements which are relevant for this question. Context I'm working on a satirical, text-based multiplayer adventure and role-playing game set in modern-day London. The game resolves around the concept of sin and features a myriad of (venomous) allusions to all the things that go wrong in this world. Players can choose between character classes like bullshit artist (consultant), bankster, lawyer, mobster, celebrity, politician, etc. In order to complete the game, the player has to live so sinfully with regard to any of the seven deadly sins that a demon is willing to offer them a contract of sponsorship. On their quest to live a sinful live, characters explore more and more locations of modern-day London (on a GoogleMap), fight "monsters" like insurance sales agents or Jehovah's Witnesses, and complete quests, like building a PowerPoint presentation out of marketing buzz words or keeping up a number of substance abuse effects in order to progress on the gluttony path. Battles are turn based with both combatants having a deck of cards, with which they try to make their enemy give in to temptations of all sorts. Tempted enemies sometimes become contacts (an item drop mechanic), which can be exploited for various benefits, depending on their area of influence (finance, underworld, bureaucracy, etc.), level of influence, and kind of sway that the player has over them (bribed, seduced, threatened, etc.) Once a contract has been exploited, the player loses that contact. Most actions require turns. Turns are limited, but refill each day. Criteria A number of peripheral game mechanics are supposed to represent real world abuses and mischief in a humorous way integrate real world data and events to strengthen the feeling of relevance of the game's humor with regard to real world problems add fun ways of interacting with other players add ways for players to express themselves through game-play Market manipulation is one such peripheral game mechanic and should fulfill all of these goals. Market manipulation This is my initial design of the mechanic: Players can enter the London Stock Exchange (LSE) (without paying a turn) LSE displays the stock prices of a number of companies in industries like weapons or tobacco as well as some derivatives based on wheat and corn. The stock prices are calculated based on the actual stock prices of these companies and derivatives (in real time) any market manipulations that were conducted by the players any market corrections of the system Players can buy and sell shares with cash, a resource in the game, at current in-game market value (without paying a turn). Players can manipulate the market, i.e. let the price of a share either rise or fall, by some amount, over a certain period of time. Manipulating the market requires 1 turn A contact in the financial sector (see above). The higher the level of influence of the contact, the stronger the effect of the manipulation on the stock price, and/or the shorter it takes for the manipulation to manifest itself. Market manipulation also adds a crime to the player's record. (There are a multitude of ways to take care of that, but it is still another "cost" of market manipulations.) The system continuously corrects market manipulations by letting the in-game prices converge towards their real world counterparts at a rate of 2% of the difference between the two per hour. Because of this market correction mechanism, pushing up prices (and screwing down prices) becomes increasingly difficult the higher (lower) the price already is. Whenever food prices reach a certain level, in-game stories are posted about hunger catastrophes happening somewhere far, far away (maybe with links to real world news stories). Whenever a player sells a certain number of shares with a sufficiently high margin, they are mentioned in that day's in-game financial news. Since the number of stock options is very limited, players will inevitably collide in their efforts to manipulate the market in their favor. Hopefully, it will also be a fun side-arena for guilds and covenants to fight each other. Question(s) What do you think of this mechanism given the criteria for peripheral game mechanics that I specified for my game? Do you have any ideas how the mechanic could be improved with regard to these criteria (or otherwise)? Could it be improved to allow for more expressive game-play, or involve an allusion to some other real world madness (like short selling, leveraging, or some other banking magic)? Are there any game-theoretic problems with this mechanic, like maybe certain dominant individual strategies that, collectively, lead to every player profiting and thus eliminating the idea of market manipulation PVP? Also, if you like (or dislike) this question, feel free to participate in the discussion on GDSE meta: "Should we be more lax with regard to SE's question/answer format to make game design questions possible?"

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  • Tweaking a few URL validation settings on ASP.NET v4.0

    - by Carlyle Dacosta
    ASP.NET has a few default settings for URLs out of the box. These can be configured quite easily in the web.config file within the  <system.web>/<httpRuntime> configuration section. Some of these are: <httpRuntime maxUrlLength=”<number here>” This number should be an integer value (defaults to 260 characters). The value must be greater than or equal to zero, though obviously small values will lead to an un-useable website. This attribute gates the length of the Url without query string. <httpRuntime maxQueryStringLength=”<number here>”. This number should be an integer value (defaults to 2048 characters). The value must be greater than or equal to zero, though obviously small values will lead to an un-useable website. <httpRuntime requestPathInvalidCharacters=”List of characters you need included in ASP.NETs validation checks” /> By default the characters are “<,>,*,%,&,:,\,?”. However once can easily change this by setting by modifying web.config. Remember, these characters can be specified in a variety of formats. For example, I want the character ‘!’ to be included in ASP.NETs URL validation logic. So I set the following: <httpRuntime requestPathInvalidCharacters=”<,>,*,%,&,:,\,?,!”. A character could also be specified in its xml encoded form. ‘&lt;;’ would mean the ‘<’ sign). I could specify the ‘!’ in its xml encoded unicode format such as requestPathInvalidCharacters=”<,>,*,%,&,:,\,?,$#x0021;” or I could specify it in its unicode encoded form or in the “<,>,*,%,&,:,\,?,%u0021” format. The following settings can be applied at Root Web.Config level, App Web.config level, Folder level or within a location tag: <location path="some path here"> <system.web> <httpRuntime maxUrlLength="" maxQueryStringLength="" requestPathInvalidChars="" /> .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } If any of the above settings fail request validation, an Http 400 “Bad Request” HttpException is thrown. These can be easily handled on the Application_Error handler on Global.asax.   Also, a new attribute in <httpRuntime /> called “relaxedUrlToFileSystemMapping” has been added with a default of false. <httpRuntime … relaxedUrlToFileSystemMapping="true|false" /> When the relaxedUrlToFileSystemMapping attribute is set to false inbound Urls still need to be valid NTFS file paths. For example Urls (sans query string) need to be less than 260 characters; no path segment within a Url can use old-style DOS device names (LPT1, COM1, etc…); Urls must be valid Windows file paths. A url like “http://digg.com/http://cnn.com” should work with this attribute set to true (of course a few characters will need to be unblocked by removing them from requestPathInvalidCharacters="" above). Managed configuration for non-NTFS-compliant Urls is determined from the first valid configuration path found when walking up the path segments of the Url. For example, if the request Url is "/foo/bar/baz/<blah>data</blah>", and there is a web.config in the "/foo/bar" directory, then the managed configuration for the request comes from merging the configuration hierarchy to include the web.config from "/foo/bar". The value of the public property HttpRequest.PhysicalPath is set to [physical file path of the application root] + "REQUEST_URL_IS_NOT_A_VALID_FILESYSTEM_PATH". For example, given a request Url like "/foo/bar/baz/<blah>data</blah>", where the application root is "/foo/bar" and the physical file path for that root is "c:\inetpub\wwwroot\foo\bar", then PhysicalPath would be "c:\inetpub\wwwroot\foo\bar\ REQUEST_URL_IS_NOT_A_VALID_FILESYSTEM_PATH".

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  • Leaks on Wikis: "Corporations...You're Next!" Oracle Desktop Virtualization Can Help.

    - by adam.hawley
    Between all the press coverage on the unauthorized release of 251,287 diplomatic documents and on previous extensive releases of classified documents on the events in Iraq and Afghanistan, one could be forgiven for thinking massive leaks are really an issue for governments, but it is not: It is an issue for corporations as well. In fact, corporations are apparently set to be the next big target for things like Wikileaks. Just the threat of such a release against one corporation recently caused the price of their stock to drop 3% after the leak organization claimed to have 5GB of information from inside the company, with the implication that it might be damaging or embarrassing information. At the moment of this blog anyway, we don't know yet if that is true or how they got the information but how did the diplomatic cable leak happen? For the diplomatic cables, according to press reports, a private in the military, with some appropriate level of security clearance (that is, he apparently had the correct level of security clearance to be accessing the information...he reportedly didn't "hack" his way through anything to get to the documents which might have raised some red flags...), is accused of accessing the material and copying it onto a writeable CD labeled "Lady Gaga" and walking out the door with it. Upload and... Done. In the same article, the accused is quoted as saying "Information should be free. It belongs in the public domain." Now think about all the confidential information in your company or non-profit... from credit card information, to phone records, to customer or donor lists, to corporate strategy documents, product cost information, etc, etc.... And then think about that last quote above from what was a very junior level person in the organization...still feeling comfortable with your ability to control all your information? So what can you do to guard against these types of breaches where there is no outsider (or even insider) intrusion to detect per se, but rather someone with malicious intent is physically walking out the door with data that they are otherwise allowed to access in their daily work? A major first step it to make it physically, logistically much harder to walk away with the information. If the user with malicious intent has no way to copy to removable or moble media (USB sticks, thumb drives, CDs, DVDs, memory cards, or even laptop disk drives) then, as a practical matter it is much more difficult to physically move the information outside the firewall. But how can you control access tightly and reliably and still keep your hundreds or even thousands of users productive in their daily job? Oracle Desktop Virtualization products can help.Oracle's comprehensive suite of desktop virtualization and access products allow your applications and, most importantly, the related data, to stay in the (highly secured) data center while still allowing secure access from just about anywhere your users need to be to be productive.  Users can securely access all the data they need to do their job, whether from work, from home, or on the road and in the field, but fully configurable policies set up centrally by privileged administrators allow you to control whether, for instance, they are allowed to print documents or use USB devices or other removable media.  Centrally set policies can also control not only whether they can download to removable devices, but also whether they can upload information (see StuxNet for why that is important...)In fact, by using Sun Ray Client desktop hardware, which does not contain any disk drives, or removable media drives, even theft of the desktop device itself would not make you vulnerable to data loss, unlike a laptop that can be stolen with hundreds of gigabytes of information on its disk drive.  And for extreme security situations, Sun Ray Clients even come standard with the ability to use fibre optic ethernet networking to each client to prevent the possibility of unauthorized monitoring of network traffic.But even without Sun Ray Client hardware, users can leverage Oracle's Secure Global Desktop software or the Oracle Virtual Desktop Client to securely access server-resident applications, desktop sessions, or full desktop virtual machines without persisting any application data on the desktop or laptop being used to access the information.  And, again, even in this context, the Oracle products allow you to control what gets uploaded, downloaded, or printed for example.Another benefit of Oracle's Desktop Virtualization and access products is the ability to rapidly and easily shut off user access centrally through administrative polices if, for example, an employee changes roles or leaves the company and should no longer have access to the information.Oracle's Desktop Virtualization suite of products can help reduce operating expense and increase user productivity, and those are good reasons alone to consider their use.  But the dynamics of today's world dictate that security is one of the top reasons for implementing a virtual desktop architecture in enterprises.For more information on these products, view the webpages on www.oracle.com and the Oracle Technology Network website.

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  • Using HTML 5 SessionState to save rendered Page Content

    - by Rick Strahl
    HTML 5 SessionState and LocalStorage are very useful and super easy to use to manage client side state. For building rich client side or SPA style applications it's a vital feature to be able to cache user data as well as HTML content in order to swap pages in and out of the browser's DOM. What might not be so obvious is that you can also use the sessionState and localStorage objects even in classic server rendered HTML applications to provide caching features between pages. These APIs have been around for a long time and are supported by most relatively modern browsers and even all the way back to IE8, so you can use them safely in your Web applications. SessionState and LocalStorage are easy The APIs that make up sessionState and localStorage are very simple. Both object feature the same API interface which  is a simple, string based key value store that has getItem, setItem, removeitem, clear and  key methods. The objects are also pseudo array objects and so can be iterated like an array with  a length property and you have array indexers to set and get values with. Basic usage  for storing and retrieval looks like this (using sessionStorage, but the syntax is the same for localStorage - just switch the objects):// set var lastAccess = new Date().getTime(); if (sessionStorage) sessionStorage.setItem("myapp_time", lastAccess.toString()); // retrieve in another page or on a refresh var time = null; if (sessionStorage) time = sessionStorage.getItem("myapp_time"); if (time) time = new Date(time * 1); else time = new Date(); sessionState stores data that is browser session specific and that has a liftetime of the active browser session or window. Shut down the browser or tab and the storage goes away. localStorage uses the same API interface, but the lifetime of the data is permanently stored in the browsers storage area until deleted via code or by clearing out browser cookies (not the cache). Both sessionStorage and localStorage space is limited. The spec is ambiguous about this - supposedly sessionStorage should allow for unlimited size, but it appears that most WebKit browsers support only 2.5mb for either object. This means you have to be careful what you store especially since other applications might be running on the same domain and also use the storage mechanisms. That said 2.5mb worth of character data is quite a bit and would go a long way. The easiest way to get a feel for how sessionState and localStorage work is to look at a simple example. You can go check out the following example online in Plunker: http://plnkr.co/edit/0ICotzkoPjHaWa70GlRZ?p=preview which looks like this: Plunker is an online HTML/JavaScript editor that lets you write and run Javascript code and similar to JsFiddle, but a bit cleaner to work in IMHO (thanks to John Papa for turning me on to it). The sample has two text boxes with counts that update session/local storage every time you click the related button. The counts are 'cached' in Session and Local storage. The point of these examples is that both counters survive full page reloads, and the LocalStorage counter survives a complete browser shutdown and restart. Go ahead and try it out by clicking the Reload button after updating both counters and then shutting down the browser completely and going back to the same URL (with the same browser). What you should see is that reloads leave both counters intact at the counted values, while a browser restart will leave only the local storage counter intact. The code to deal with the SessionStorage (and LocalStorage not shown here) in the example is isolated into a couple of wrapper methods to simplify the code: function getSessionCount() { var count = 0; if (sessionStorage) { var count = sessionStorage.getItem("ss_count"); count = !count ? 0 : count * 1; } $("#txtSession").val(count); return count; } function setSessionCount(count) { if (sessionStorage) sessionStorage.setItem("ss_count", count.toString()); } These two functions essentially load and store a session counter value. The two key methods used here are: sessionStorage.getItem(key); sessionStorage.setItem(key,stringVal); Note that the value given to setItem and return by getItem has to be a string. If you pass another type you get an error. Don't let that limit you though - you can easily enough store JSON data in a variable so it's quite possible to pass complex objects and store them into a single sessionStorage value:var user = { name: "Rick", id="ricks", level=8 } sessionStorage.setItem("app_user",JSON.stringify(user)); to retrieve it:var user = sessionStorage.getItem("app_user"); if (user) user = JSON.parse(user); Simple! If you're using the Chrome Developer Tools (F12) you can also check out the session and local storage state on the Resource tab:   You can also use this tool to refresh or remove entries from storage. What we just looked at is a purely client side implementation where a couple of counters are stored. For rich client centric AJAX applications sessionStorage and localStorage provide a very nice and simple API to store application state while the application is running. But you can also use these storage mechanisms to manage server centric HTML applications when you combine server rendering with some JavaScript to perform client side data caching. You can both store some state information and data on the client (ie. store a JSON object and carry it forth between server rendered HTML requests) or you can use it for good old HTTP based caching where some rendered HTML is saved and then restored later. Let's look at the latter with a real life example. Why do I need Client-side Page Caching for Server Rendered HTML? I don't know about you, but in a lot of my existing server driven applications I have lists that display a fair amount of data. Typically these lists contain links to then drill down into more specific data either for viewing or editing. You can then click on a link and go off to a detail page that provides more concise content. So far so good. But now you're done with the detail page and need to get back to the list, so you click on a 'bread crumbs trail' or an application level 'back to list' button and… …you end up back at the top of the list - the scroll position, the current selection in some cases even filters conditions - all gone with the wind. You've left behind the state of the list and are starting from scratch in your browsing of the list from the top. Not cool! Sound familiar? This a pretty common scenario with server rendered HTML content where it's so common to display lists to drill into, only to lose state in the process of returning back to the original list. Look at just about any traditional forums application, or even StackOverFlow to see what I mean here. Scroll down a bit to look at a post or entry, drill in then use the bread crumbs or tab to go back… In some cases returning to the top of a list is not a big deal. On StackOverFlow that sort of works because content is turning around so quickly you probably want to actually look at the top posts. Not always though - if you're browsing through a list of search topics you're interested in and drill in there's no way back to that position. Essentially anytime you're actively browsing the items in the list, that's when state becomes important and if it's not handled the user experience can be really disrupting. Content Caching If you're building client centric SPA style applications this is a fairly easy to solve problem - you tend to render the list once and then update the page content to overlay the detail content, only hiding the list temporarily until it's used again later. It's relatively easy to accomplish this simply by hiding content on the page and later making it visible again. But if you use server rendered content, hanging on to all the detail like filters, selections and scroll position is not quite as easy. Or is it??? This is where sessionStorage comes in handy. What if we just save the rendered content of a previous page, and then restore it when we return to this page based on a special flag that tells us to use the cached version? Let's see how we can do this. A real World Use Case Recently my local ISP asked me to help out with updating an ancient classifieds application. They had a very busy, local classifieds app that was originally an ASP classic application. The old app was - wait for it: frames based - and even though I lobbied against it, the decision was made to keep the frames based layout to allow rapid browsing of the hundreds of posts that are made on a daily basis. The primary reason they wanted this was precisely for the ability to quickly browse content item by item. While I personally hate working with Frames, I have to admit that the UI actually works well with the frames layout as long as you're running on a large desktop screen. You can check out the frames based desktop site here: http://classifieds.gorge.net/ However when I rebuilt the app I also added a secondary view that doesn't use frames. The main reason for this of course was for mobile displays which work horribly with frames. So there's a somewhat mobile friendly interface to the interface, which ditches the frames and uses some responsive design tweaking for mobile capable operation: http://classifeds.gorge.net/mobile  (or browse the base url with your browser width under 800px)   Here's what the mobile, non-frames view looks like:   As you can see this means that the list of classifieds posts now is a list and there's a separate page for drilling down into the item. And of course… originally we ran into that usability issue I mentioned earlier where the browse, view detail, go back to the list cycle resulted in lost list state. Originally in mobile mode you scrolled through the list, found an item to look at and drilled in to display the item detail. Then you clicked back to the list and BAM - you've lost your place. Because there are so many items added on a daily basis the full list is never fully loaded, but rather there's a "Load Additional Listings"  entry at the button. Not only did we originally lose our place when coming back to the list, but any 'additionally loaded' items are no longer there because the list was now rendering  as if it was the first page hit. The additional listings, and any filters, the selection of an item all were lost. Major Suckage! Using Client SessionStorage to cache Server Rendered Content To work around this problem I decided to cache the rendered page content from the list in SessionStorage. Anytime the list renders or is updated with Load Additional Listings, the page HTML is cached and stored in Session Storage. Any back links from the detail page or the login or write entry forms then point back to the list page with a back=true query string parameter. If the server side sees this parameter it doesn't render the part of the page that is cached. Instead the client side code retrieves the data from the sessionState cache and simply inserts it into the page. It sounds pretty simple, and the overall the process is really easy, but there are a few gotchas that I'll discuss in a minute. But first let's look at the implementation. Let's start with the server side here because that'll give a quick idea of the doc structure. As I mentioned the server renders data from an ASP.NET MVC view. On the list page when returning to the list page from the display page (or a host of other pages) looks like this: https://classifieds.gorge.net/list?back=True The query string value is a flag, that indicates whether the server should render the HTML. Here's what the top level MVC Razor view for the list page looks like:@model MessageListViewModel @{ ViewBag.Title = "Classified Listing"; bool isBack = !string.IsNullOrEmpty(Request.QueryString["back"]); } <form method="post" action="@Url.Action("list")"> <div id="SizingContainer"> @if (!isBack) { @Html.Partial("List_CommandBar_Partial", Model) <div id="PostItemContainer" class="scrollbox" xstyle="-webkit-overflow-scrolling: touch;"> @Html.Partial("List_Items_Partial", Model) @if (Model.RequireLoadEntry) { <div class="postitem loadpostitems" style="padding: 15px;"> <div id="LoadProgress" class="smallprogressright"></div> <div class="control-progress"> Load additional listings... </div> </div> } </div> } </div> </form> As you can see the query string triggers a conditional block that if set is simply not rendered. The content inside of #SizingContainer basically holds  the entire page's HTML sans the headers and scripts, but including the filter options and menu at the top. In this case this makes good sense - in other situations the fact that the menu or filter options might be dynamically updated might make you only cache the list rather than essentially the entire page. In this particular instance all of the content works and produces the proper result as both the list along with any filter conditions in the form inputs are restored. Ok, let's move on to the client. On the client there are two page level functions that deal with saving and restoring state. Like the counter example I showed earlier, I like to wrap the logic to save and restore values from sessionState into a separate function because they are almost always used in several places.page.saveData = function(id) { if (!sessionStorage) return; var data = { id: id, scroll: $("#PostItemContainer").scrollTop(), html: $("#SizingContainer").html() }; sessionStorage.setItem("list_html",JSON.stringify(data)); }; page.restoreData = function() { if (!sessionStorage) return; var data = sessionStorage.getItem("list_html"); if (!data) return null; return JSON.parse(data); }; The data that is saved is an object which contains an ID which is the selected element when the user clicks and a scroll position. These two values are used to reset the scroll position when the data is used from the cache. Finally the html from the #SizingContainer element is stored, which makes for the bulk of the document's HTML. In this application the HTML captured could be a substantial bit of data. If you recall, I mentioned that the server side code renders a small chunk of data initially and then gets more data if the user reads through the first 50 or so items. The rest of the items retrieved can be rather sizable. Other than the JSON deserialization that's Ok. Since I'm using SessionStorage the storage space has no immediate limits. Next is the core logic to handle saving and restoring the page state. At first though this would seem pretty simple, and in some cases it might be, but as the following code demonstrates there are a few gotchas to watch out for. Here's the relevant code I use to save and restore:$( function() { … var isBack = getUrlEncodedKey("back", location.href); if (isBack) { // remove the back key from URL setUrlEncodedKey("back", "", location.href); var data = page.restoreData(); // restore from sessionState if (!data) { // no data - force redisplay of the server side default list window.location = "list"; return; } $("#SizingContainer").html(data.html); var el = $(".postitem[data-id=" + data.id + "]"); $(".postitem").removeClass("highlight"); el.addClass("highlight"); $("#PostItemContainer").scrollTop(data.scroll); setTimeout(function() { el.removeClass("highlight"); }, 2500); } else if (window.noFrames) page.saveData(null); // save when page loads $("#SizingContainer").on("click", ".postitem", function() { var id = $(this).attr("data-id"); if (!id) return true; if (window.noFrames) page.saveData(id); var contentFrame = window.parent.frames["Content"]; if (contentFrame) contentFrame.location.href = "show/" + id; else window.location.href = "show/" + id; return false; }); … The code starts out by checking for the back query string flag which triggers restoring from the client cache. If cached the cached data structure is read from sessionStorage. It's important here to check if data was returned. If the user had back=true on the querystring but there is no cached data, he likely bookmarked this page or otherwise shut down the browser and came back to this URL. In that case the server didn't render any detail and we have no cached data, so all we can do is redirect to the original default list view using window.location. If we continued the page would render no data - so make sure to always check the cache retrieval result. Always! If there is data the it's loaded and the data.html data is restored back into the document by simply injecting the HTML back into the document's #SizingContainer element:$("#SizingContainer").html(data.html); It's that simple and it's quite quick even with a fully loaded list of additional items and on a phone. The actual HTML data is stored to the cache on every page load initially and then again when the user clicks on an element to navigate to a particular listing. The former ensures that the client cache always has something in it, and the latter updates with additional information for the selected element. For the click handling I use a data-id attribute on the list item (.postitem) in the list and retrieve the id from that. That id is then used to navigate to the actual entry as well as storing that Id value in the saved cached data. The id is used to reset the selection by searching for the data-id value in the restored elements. The overall process of this save/restore process is pretty straight forward and it doesn't require a bunch of code, yet it yields a huge improvement in the usability of the site on mobile devices (or anybody who uses the non-frames view). Some things to watch out for As easy as it conceptually seems to simply store and retrieve cached content, you have to be quite aware what type of content you are caching. The code above is all that's specific to cache/restore cycle and it works, but it took a few tweaks to the rest of the script code and server code to make it all work. There were a few gotchas that weren't immediately obvious. Here are a few things to pay attention to: Event Handling Logic Timing of manipulating DOM events Inline Script Code Bookmarking to the Cache Url when no cache exists Do you have inline script code in your HTML? That script code isn't going to run if you restore from cache and simply assign or it may not run at the time you think it would normally in the DOM rendering cycle. JavaScript Event Hookups The biggest issue I ran into with this approach almost immediately is that originally I had various static event handlers hooked up to various UI elements that are now cached. If you have an event handler like:$("#btnSearch").click( function() {…}); that works fine when the page loads with server rendered HTML, but that code breaks when you now load the HTML from cache. Why? Because the elements you're trying to hook those events to may not actually be there - yet. Luckily there's an easy workaround for this by using deferred events. With jQuery you can use the .on() event handler instead:$("#SelectionContainer").on("click","#btnSearch", function() {…}); which monitors a parent element for the events and checks for the inner selector elements to handle events on. This effectively defers to runtime event binding, so as more items are added to the document bindings still work. For any cached content use deferred events. Timing of manipulating DOM Elements Along the same lines make sure that your DOM manipulation code follows the code that loads the cached content into the page so that you don't manipulate DOM elements that don't exist just yet. Ideally you'll want to check for the condition to restore cached content towards the top of your script code, but that can be tricky if you have components or other logic that might not all run in a straight line. Inline Script Code Here's another small problem I ran into: I use a DateTime Picker widget I built a while back that relies on the jQuery date time picker. I also created a helper function that allows keyboard date navigation into it that uses JavaScript logic. Because MVC's limited 'object model' the only way to embed widget content into the page is through inline script. This code broken when I inserted the cached HTML into the page because the script code was not available when the component actually got injected into the page. As the last bullet - it's a matter of timing. There's no good work around for this - in my case I pulled out the jQuery date picker and relied on native <input type="date" /> logic instead - a better choice these days anyway, especially since this view is meant to be primarily to serve mobile devices which actually support date input through the browser (unlike desktop browsers of which only WebKit seems to support it). Bookmarking Cached Urls When you cache HTML content you have to make a decision whether you cache on the client and also not render that same content on the server. In the Classifieds app I didn't render server side content so if the user comes to the page with back=True and there is no cached content I have to a have a Plan B. Typically this happens when somebody ends up bookmarking the back URL. The easiest and safest solution for this scenario is to ALWAYS check the cache result to make sure it exists and if not have a safe URL to go back to - in this case to the plain uncached list URL which amounts to effectively redirecting. This seems really obvious in hindsight, but it's easy to overlook and not see a problem until much later, when it's not obvious at all why the page is not rendering anything. Don't use <body> to replace Content Since we're practically replacing all the HTML in the page it may seem tempting to simply replace the HTML content of the <body> tag. Don't. The body tag usually contains key things that should stay in the page and be there when it loads. Specifically script tags and elements and possibly other embedded content. It's best to create a top level DOM element specifically as a placeholder container for your cached content and wrap just around the actual content you want to replace. In the app above the #SizingContainer is that container. Other Approaches The approach I've used for this application is kind of specific to the existing server rendered application we're running and so it's just one approach you can take with caching. However for server rendered content caching this is a pattern I've used in a few apps to retrofit some client caching into list displays. In this application I took the path of least resistance to the existing server rendering logic. Here are a few other ways that come to mind: Using Partial HTML Rendering via AJAXInstead of rendering the page initially on the server, the page would load empty and the client would render the UI by retrieving the respective HTML and embedding it into the page from a Partial View. This effectively makes the initial rendering and the cached rendering logic identical and removes the server having to decide whether this request needs to be rendered or not (ie. not checking for a back=true switch). All the logic related to caching is made on the client in this case. Using JSON Data and Client RenderingThe hardcore client option is to do the whole UI SPA style and pull data from the server and then use client rendering or databinding to pull the data down and render using templates or client side databinding with knockout/angular et al. As with the Partial Rendering approach the advantage is that there's no difference in the logic between pulling the data from cache or rendering from scratch other than the initial check for the cache request. Of course if the app is a  full on SPA app, then caching may not be required even - the list could just stay in memory and be hidden and reactivated. I'm sure there are a number of other ways this can be handled as well especially using  AJAX. AJAX rendering might simplify the logic, but it also complicates search engine optimization since there's no content loaded initially. So there are always tradeoffs and it's important to look at all angles before deciding on any sort of caching solution in general. State of the Session SessionState and LocalStorage are easy to use in client code and can be integrated even with server centric applications to provide nice caching features of content and data. In this post I've shown a very specific scenario of storing HTML content for the purpose of remembering list view data and state and making the browsing experience for lists a bit more friendly, especially if there's dynamically loaded content involved. If you haven't played with sessionStorage or localStorage I encourage you to give it a try. There's a lot of cool stuff that you can do with this beyond the specific scenario I've covered here… Resources Overview of localStorage (also applies to sessionStorage) Web Storage Compatibility Modernizr Test Suite© Rick Strahl, West Wind Technologies, 2005-2013Posted in JavaScript  HTML5  ASP.NET  MVC   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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  • Silverlight Firestarter Wrap Up and WCF RIA Services Talk Sample Code

    - by dwahlin
    I had a great time attending and speaking at the Silverlight Firestarter event up in Redmond on December 2, 2010. In addition to getting a chance to hang out with a lot of cool people from Microsoft such as Scott Guthrie, John Papa, Tim Heuer, Brian Goldfarb, John Allwright, David Pugmire, Jesse Liberty, Jeff Handley, Yavor Georgiev, Jossef Goldberg, Mike Cook and many others, I also had a chance to chat with a lot of people attending the event and hear about what projects they’re working on which was awesome. If you didn’t get a chance to look through all of the new features coming in Silverlight 5 check out John Papa’s post on the subject. While at the Silverlight Firestarter event I gave a presentation on WCF RIA Services and wanted to get the code posted since several people have asked when it’d be available. The talk can be viewed by clicking the image below. Code from the talk follows as well as additional links. I had a few people ask about the green bracelet on my left hand since it looks like something you’d get from a waterpark. It was used to get us access down a little hall that led backstage and allowed us to go backstage during the event. I thought it looked kind of dorky but it was required to get through security. Sample Code from My WCF RIA Services Talk (To login to the 2 apps use “user” and “P@ssw0rd”. Make sure to do a rebuild of the projects in Visual Studio before running them.) View All Silverlight Firestarter Talks and Scott Guthrie’s Keynote WCF RIA Services SP1 Beta for Silverlight 4 WCF RIA Services Code Samples (including some SP1 samples) Improved binding support in EntitySet and EntityCollection with SP1 (Kyle McClellan’s Blog) Introducing an MVVM-Friendly DomainDataSource: The DomainCollectionView (Kyle McClellan’s Blog) I’ve had the chance to speak at a lot of conferences but never with as many cameras, streaming capabilities, people watching live and overall hype involved. Over 1000 people registered to attend the conference in person at the Microsoft campus and well over 15,000 to watch it through the live stream.  The event started for me on Tuesday afternoon with a flight up to Seattle from Phoenix. My flight was delayed 1 1/2 hours (I seem to be good at booking delayed flights) so I didn’t get up there until almost 8 PM. John Papa did a tech check at 9 PM that night and I was scheduled for 9:30 PM. We basically plugged in my laptop backstage (amazing number of servers, racks and audio devices back there) and made sure everything showed up properly on the projector and the machines recording the presentation. In addition to a dedicated show director, there were at least 5 tech people back stage and at least that many up in the booth running lights, audio, cameras, and other aspects of the show. I wish I would’ve taken a picture of the backstage setup since it was pretty massive – servers all over the place. I definitely gained a new appreciation for how much work goes into these types of events. Here’s what the room looked like right before my tech check– not real exciting at this point. That’s Yavor Georgiev (who spoke on WCF Services at the Firestarter) in the background. We had plenty of monitors to reference during the presentation. Two monitors for slides (right and left side) and a notes monitor. The 4th monitor showed the time and they’d type in notes to us as we talked (such as “You’re over time!” in my case since I went around 4 minutes over :-)). Wednesday morning I went back on campus at Microsoft and watched John Papa film a few Silverlight TV episodes with Dave Campbell and Ryan Plemons.   Next I had the chance to watch the dry run of the keynote with Scott Guthrie and John Papa. We were all blown away by the demos shown since they were even better than expected. Starting at 1 PM on Wednesday I went over to Building 35 and listened to Yavor Georgiev (WCF Services), Jaime Rodriguez (Windows Phone 7), Jesse Liberty (Data Binding) and Jossef Goldberg and Mike Cook (Silverlight Performance) give their different talks and we all shared feedback with each other which was a lot of fun. Jeff Handley from the RIA Services team came afterwards and listened to me give a dry run of my WCF RIA Services talk. He had some great feedback that I really appreciated getting. That night I hung out with John Papa and Ward Bell and listened to John walk through his keynote demos. I also got a sneak peak of the gift given to Dave Campbell for all his work with Silverlight Cream over the years. It’s a poster signed by all of the key people involved with Silverlight: Thursday morning I got up fairly early to get to the event center by 8 AM for speaker pictures. It was nice and quiet at that point although outside the room there was a huge line of people waiting to get in.     At around 8:30 AM everyone was let in and the main room was filled quickly. Two other overflow rooms in the Microsoft conference center (Building 33) were also filled to capacity. At around 9 AM Scott Guthrie kicked off the event and all the excitement started! From there it was all a blur but it was definitely a lot of fun. All of the sessions for the Silverlight Firestarter were recorded and can be watched here (including the keynote). Corey Schuman, John Papa and I also released 11 lab exercises and associated videos to help people get started with Silverlight. Definitely check them out if you’re interested in learning more! Level 100: Getting Started Lab 01 - WinForms and Silverlight Lab 02 - ASP.NET and Silverlight Lab 03 - XAML and Controls Lab 04 - Data Binding Level 200: Ready for More Lab 05 - Migrating Apps to Out-of-Browser Lab 06 - Great UX with Blend Lab 07 - Web Services and Silverlight Lab 08 - Using WCF RIA Services Level 300: Take me Further Lab 09 - Deep Dive into Out-of-Browser Lab 10 - Silverlight Patterns: Using MVVM Lab 11 - Silverlight and Windows Phone 7

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  • Smarter, Faster, Cheaper: The Insurance Industry’s Dream

    - by Jenna Danko
    On June 3rd, I saw the Gaylord Resort Centre in Washington D.C. become the hub of C level executives and managers of insurance carriers for the IASA 2013 Conference.  Insurance Accounting/Regulation and Technology sessions took the focus, but there were plenty of tertiary sessions for career development, which complemented the overall strong networking side of the conference.  As an exhibitor, Oracle, along with several hundred other product providers, welcomed the opportunity to display and demonstrate our solutions and we were encouraged by hustle and bustle of the exhibition floor.  The IASA organizers had pre-arranged fast track tours whereby interested conference delegates could sign up for a series of like-themed presentations from Vendors, giving them a level of 'Speed Dating' introductions to possible solutions and services.  Oracle participated in a number of these, which were very well subscribed.  Clearly, the conference had a strong business focus; however, attendees saw technology as a key enabler to get their processes done smarter, faster and cheaper.  As we navigated through the exhibition, it became clear from the inquiries that came to us that insurance carriers are gravitating to a number of focus areas: Navigating the maze of upcoming regulatory reporting changes. For US carriers with European holdings, Solvency II carries a myriad of rules and reporting requirements. Alignment across the globe of the Own Risk and Solvency Assessment (ORSA) processes brings to the fore the National Insurance of Insurance commissioners' (NAIC) recent guidance manual publication. Doing more with less and to certainly expect more from technology for less dollars. The overall cost of IT, in particular hardware, has dropped in real terms (though the appetite for more has risen: more CPU, more RAM, more storage), but software has seen less change. Clearly, customers expect either to pay less or get a lot more from their software solutions for the same buck. Doing things smarter – A recognition that with the advance of technology to stand still no longer means you are technically going backwards. Technology and, in particular technology interactions with human business processes, has undergone incredible change over the past 5 years. Consumer usage (iPhones, etc.) has been at the forefront, but now at the Enterprise level ever more effective technology exploitation is beginning to take place. That data and, in particular gleaning knowledge from data, is refining and improving business processes.  Organizations are now consuming more data than ever before, and it is set to grow exponentially for some time to come.  Amassing large volumes of data is one thing, but effectively analyzing that data is another.  It is the results of such analysis that leads to improvements both in terms of insurance product offerings and the processes to support them. Regulatory Compliance, damned if you do and damned if you don’t! Clearly, around the globe at lot is changing from a regulatory perspective and it is evident that in terms of regulatory requirements, whilst there is a greater convergence across jurisdictions bringing uniformity, there is also a lot of work to be done in the next 5 years. Just like the big data, hidden behind effective regulatory compliance there often lies golden nuggets that can give competitive advantages. From Oracle's perspective, our Rating Engine, Billing, Document Management and Insurance Analytics solutions on display served to strike up good conversations and, as is always the case at conferences, it was a great opportunity to meet and speak with existing Oracle customers that we might not have otherwise caught up with for a while. Fortunately, I was able to catch up on a few sessions at the close of the Exhibition.  The speaker quality was high and the audience asked challenging, but pertinent, questions.  During Dr. Jackie Freiberg’s keynote “Bye Bye Business as Usual,” the author discussed 8 strategies to help leaders create a culture where teams consistently deliver innovative ideas by disrupting the status quo.  The very first strategy: Get wired for innovation.  Freiberg admitted that folks in the insurance and financial services industry understand and know innovation is important, but oftentimes they are slow adopters.  Today, technology and innovation go hand in hand. In speaking to delegates during and after the conference, a high degree of satisfaction could be measured from their positive comments of speaker sessions and the exhibitors. I suspect many will be back in 2014 with Indianapolis as the conference location. Did you attend the IASA Conference in Washington D.C.?  If so, I would love to hear your comments. Andrew Collins is the Director, Solvency II of Oracle Financial Services. He can be reached at andrew.collins AT oracle.com.

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  • value types in the vm

    - by john.rose
    value types in the vm p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Times} p.p2 {margin: 0.0px 0.0px 14.0px 0.0px; font: 14.0px Times} p.p3 {margin: 0.0px 0.0px 12.0px 0.0px; font: 14.0px Times} p.p4 {margin: 0.0px 0.0px 15.0px 0.0px; font: 14.0px Times} p.p5 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Courier} p.p6 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Courier; min-height: 17.0px} p.p7 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Times; min-height: 18.0px} p.p8 {margin: 0.0px 0.0px 0.0px 36.0px; text-indent: -36.0px; font: 14.0px Times; min-height: 18.0px} p.p9 {margin: 0.0px 0.0px 12.0px 0.0px; font: 14.0px Times; min-height: 18.0px} p.p10 {margin: 0.0px 0.0px 12.0px 0.0px; font: 14.0px Times; color: #000000} li.li1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Times} li.li7 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Times; min-height: 18.0px} span.s1 {font: 14.0px Courier} span.s2 {color: #000000} span.s3 {font: 14.0px Courier; color: #000000} ol.ol1 {list-style-type: decimal} Or, enduring values for a changing world. Introduction A value type is a data type which, generally speaking, is designed for being passed by value in and out of methods, and stored by value in data structures. The only value types which the Java language directly supports are the eight primitive types. Java indirectly and approximately supports value types, if they are implemented in terms of classes. For example, both Integer and String may be viewed as value types, especially if their usage is restricted to avoid operations appropriate to Object. In this note, we propose a definition of value types in terms of a design pattern for Java classes, accompanied by a set of usage restrictions. We also sketch the relation of such value types to tuple types (which are a JVM-level notion), and point out JVM optimizations that can apply to value types. This note is a thought experiment to extend the JVM’s performance model in support of value types. The demonstration has two phases.  Initially the extension can simply use design patterns, within the current bytecode architecture, and in today’s Java language. But if the performance model is to be realized in practice, it will probably require new JVM bytecode features, changes to the Java language, or both.  We will look at a few possibilities for these new features. An Axiom of Value In the context of the JVM, a value type is a data type equipped with construction, assignment, and equality operations, and a set of typed components, such that, whenever two variables of the value type produce equal corresponding values for their components, the values of the two variables cannot be distinguished by any JVM operation. Here are some corollaries: A value type is immutable, since otherwise a copy could be constructed and the original could be modified in one of its components, allowing the copies to be distinguished. Changing the component of a value type requires construction of a new value. The equals and hashCode operations are strictly component-wise. If a value type is represented by a JVM reference, that reference cannot be successfully synchronized on, and cannot be usefully compared for reference equality. A value type can be viewed in terms of what it doesn’t do. We can say that a value type omits all value-unsafe operations, which could violate the constraints on value types.  These operations, which are ordinarily allowed for Java object types, are pointer equality comparison (the acmp instruction), synchronization (the monitor instructions), all the wait and notify methods of class Object, and non-trivial finalize methods. The clone method is also value-unsafe, although for value types it could be treated as the identity function. Finally, and most importantly, any side effect on an object (however visible) also counts as an value-unsafe operation. A value type may have methods, but such methods must not change the components of the value. It is reasonable and useful to define methods like toString, equals, and hashCode on value types, and also methods which are specifically valuable to users of the value type. Representations of Value Value types have two natural representations in the JVM, unboxed and boxed. An unboxed value consists of the components, as simple variables. For example, the complex number x=(1+2i), in rectangular coordinate form, may be represented in unboxed form by the following pair of variables: /*Complex x = Complex.valueOf(1.0, 2.0):*/ double x_re = 1.0, x_im = 2.0; These variables might be locals, parameters, or fields. Their association as components of a single value is not defined to the JVM. Here is a sample computation which computes the norm of the difference between two complex numbers: double distance(/*Complex x:*/ double x_re, double x_im,         /*Complex y:*/ double y_re, double y_im) {     /*Complex z = x.minus(y):*/     double z_re = x_re - y_re, z_im = x_im - y_im;     /*return z.abs():*/     return Math.sqrt(z_re*z_re + z_im*z_im); } A boxed representation groups component values under a single object reference. The reference is to a ‘wrapper class’ that carries the component values in its fields. (A primitive type can naturally be equated with a trivial value type with just one component of that type. In that view, the wrapper class Integer can serve as a boxed representation of value type int.) The unboxed representation of complex numbers is practical for many uses, but it fails to cover several major use cases: return values, array elements, and generic APIs. The two components of a complex number cannot be directly returned from a Java function, since Java does not support multiple return values. The same story applies to array elements: Java has no ’array of structs’ feature. (Double-length arrays are a possible workaround for complex numbers, but not for value types with heterogeneous components.) By generic APIs I mean both those which use generic types, like Arrays.asList and those which have special case support for primitive types, like String.valueOf and PrintStream.println. Those APIs do not support unboxed values, and offer some problems to boxed values. Any ’real’ JVM type should have a story for returns, arrays, and API interoperability. The basic problem here is that value types fall between primitive types and object types. Value types are clearly more complex than primitive types, and object types are slightly too complicated. Objects are a little bit dangerous to use as value carriers, since object references can be compared for pointer equality, and can be synchronized on. Also, as many Java programmers have observed, there is often a performance cost to using wrapper objects, even on modern JVMs. Even so, wrapper classes are a good starting point for talking about value types. If there were a set of structural rules and restrictions which would prevent value-unsafe operations on value types, wrapper classes would provide a good notation for defining value types. This note attempts to define such rules and restrictions. Let’s Start Coding Now it is time to look at some real code. Here is a definition, written in Java, of a complex number value type. @ValueSafe public final class Complex implements java.io.Serializable {     // immutable component structure:     public final double re, im;     private Complex(double re, double im) {         this.re = re; this.im = im;     }     // interoperability methods:     public String toString() { return "Complex("+re+","+im+")"; }     public List<Double> asList() { return Arrays.asList(re, im); }     public boolean equals(Complex c) {         return re == c.re && im == c.im;     }     public boolean equals(@ValueSafe Object x) {         return x instanceof Complex && equals((Complex) x);     }     public int hashCode() {         return 31*Double.valueOf(re).hashCode()                 + Double.valueOf(im).hashCode();     }     // factory methods:     public static Complex valueOf(double re, double im) {         return new Complex(re, im);     }     public Complex changeRe(double re2) { return valueOf(re2, im); }     public Complex changeIm(double im2) { return valueOf(re, im2); }     public static Complex cast(@ValueSafe Object x) {         return x == null ? ZERO : (Complex) x;     }     // utility methods and constants:     public Complex plus(Complex c)  { return new Complex(re+c.re, im+c.im); }     public Complex minus(Complex c) { return new Complex(re-c.re, im-c.im); }     public double abs() { return Math.sqrt(re*re + im*im); }     public static final Complex PI = valueOf(Math.PI, 0.0);     public static final Complex ZERO = valueOf(0.0, 0.0); } This is not a minimal definition, because it includes some utility methods and other optional parts.  The essential elements are as follows: The class is marked as a value type with an annotation. The class is final, because it does not make sense to create subclasses of value types. The fields of the class are all non-private and final.  (I.e., the type is immutable and structurally transparent.) From the supertype Object, all public non-final methods are overridden. The constructor is private. Beyond these bare essentials, we can observe the following features in this example, which are likely to be typical of all value types: One or more factory methods are responsible for value creation, including a component-wise valueOf method. There are utility methods for complex arithmetic and instance creation, such as plus and changeIm. There are static utility constants, such as PI. The type is serializable, using the default mechanisms. There are methods for converting to and from dynamically typed references, such as asList and cast. The Rules In order to use value types properly, the programmer must avoid value-unsafe operations.  A helpful Java compiler should issue errors (or at least warnings) for code which provably applies value-unsafe operations, and should issue warnings for code which might be correct but does not provably avoid value-unsafe operations.  No such compilers exist today, but to simplify our account here, we will pretend that they do exist. A value-safe type is any class, interface, or type parameter marked with the @ValueSafe annotation, or any subtype of a value-safe type.  If a value-safe class is marked final, it is in fact a value type.  All other value-safe classes must be abstract.  The non-static fields of a value class must be non-public and final, and all its constructors must be private. Under the above rules, a standard interface could be helpful to define value types like Complex.  Here is an example: @ValueSafe public interface ValueType extends java.io.Serializable {     // All methods listed here must get redefined.     // Definitions must be value-safe, which means     // they may depend on component values only.     List<? extends Object> asList();     int hashCode();     boolean equals(@ValueSafe Object c);     String toString(); } //@ValueSafe inherited from supertype: public final class Complex implements ValueType { … The main advantage of such a conventional interface is that (unlike an annotation) it is reified in the runtime type system.  It could appear as an element type or parameter bound, for facilities which are designed to work on value types only.  More broadly, it might assist the JVM to perform dynamic enforcement of the rules for value types. Besides types, the annotation @ValueSafe can mark fields, parameters, local variables, and methods.  (This is redundant when the type is also value-safe, but may be useful when the type is Object or another supertype of a value type.)  Working forward from these annotations, an expression E is defined as value-safe if it satisfies one or more of the following: The type of E is a value-safe type. E names a field, parameter, or local variable whose declaration is marked @ValueSafe. E is a call to a method whose declaration is marked @ValueSafe. E is an assignment to a value-safe variable, field reference, or array reference. E is a cast to a value-safe type from a value-safe expression. E is a conditional expression E0 ? E1 : E2, and both E1 and E2 are value-safe. Assignments to value-safe expressions and initializations of value-safe names must take their values from value-safe expressions. A value-safe expression may not be the subject of a value-unsafe operation.  In particular, it cannot be synchronized on, nor can it be compared with the “==” operator, not even with a null or with another value-safe type. In a program where all of these rules are followed, no value-type value will be subject to a value-unsafe operation.  Thus, the prime axiom of value types will be satisfied, that no two value type will be distinguishable as long as their component values are equal. More Code To illustrate these rules, here are some usage examples for Complex: Complex pi = Complex.valueOf(Math.PI, 0); Complex zero = pi.changeRe(0);  //zero = pi; zero.re = 0; ValueType vtype = pi; @SuppressWarnings("value-unsafe")   Object obj = pi; @ValueSafe Object obj2 = pi; obj2 = new Object();  // ok List<Complex> clist = new ArrayList<Complex>(); clist.add(pi);  // (ok assuming List.add param is @ValueSafe) List<ValueType> vlist = new ArrayList<ValueType>(); vlist.add(pi);  // (ok) List<Object> olist = new ArrayList<Object>(); olist.add(pi);  // warning: "value-unsafe" boolean z = pi.equals(zero); boolean z1 = (pi == zero);  // error: reference comparison on value type boolean z2 = (pi == null);  // error: reference comparison on value type boolean z3 = (pi == obj2);  // error: reference comparison on value type synchronized (pi) { }  // error: synch of value, unpredictable result synchronized (obj2) { }  // unpredictable result Complex qq = pi; qq = null;  // possible NPE; warning: “null-unsafe" qq = (Complex) obj;  // warning: “null-unsafe" qq = Complex.cast(obj);  // OK @SuppressWarnings("null-unsafe")   Complex empty = null;  // possible NPE qq = empty;  // possible NPE (null pollution) The Payoffs It follows from this that either the JVM or the java compiler can replace boxed value-type values with unboxed ones, without affecting normal computations.  Fields and variables of value types can be split into their unboxed components.  Non-static methods on value types can be transformed into static methods which take the components as value parameters. Some common questions arise around this point in any discussion of value types. Why burden the programmer with all these extra rules?  Why not detect programs automagically and perform unboxing transparently?  The answer is that it is easy to break the rules accidently unless they are agreed to by the programmer and enforced.  Automatic unboxing optimizations are tantalizing but (so far) unreachable ideal.  In the current state of the art, it is possible exhibit benchmarks in which automatic unboxing provides the desired effects, but it is not possible to provide a JVM with a performance model that assures the programmer when unboxing will occur.  This is why I’m writing this note, to enlist help from, and provide assurances to, the programmer.  Basically, I’m shooting for a good set of user-supplied “pragmas” to frame the desired optimization. Again, the important thing is that the unboxing must be done reliably, or else programmers will have no reason to work with the extra complexity of the value-safety rules.  There must be a reasonably stable performance model, wherein using a value type has approximately the same performance characteristics as writing the unboxed components as separate Java variables. There are some rough corners to the present scheme.  Since Java fields and array elements are initialized to null, value-type computations which incorporate uninitialized variables can produce null pointer exceptions.  One workaround for this is to require such variables to be null-tested, and the result replaced with a suitable all-zero value of the value type.  That is what the “cast” method does above. Generically typed APIs like List<T> will continue to manipulate boxed values always, at least until we figure out how to do reification of generic type instances.  Use of such APIs will elicit warnings until their type parameters (and/or relevant members) are annotated or typed as value-safe.  Retrofitting List<T> is likely to expose flaws in the present scheme, which we will need to engineer around.  Here are a couple of first approaches: public interface java.util.List<@ValueSafe T> extends Collection<T> { … public interface java.util.List<T extends Object|ValueType> extends Collection<T> { … (The second approach would require disjunctive types, in which value-safety is “contagious” from the constituent types.) With more transformations, the return value types of methods can also be unboxed.  This may require significant bytecode-level transformations, and would work best in the presence of a bytecode representation for multiple value groups, which I have proposed elsewhere under the title “Tuples in the VM”. But for starters, the JVM can apply this transformation under the covers, to internally compiled methods.  This would give a way to express multiple return values and structured return values, which is a significant pain-point for Java programmers, especially those who work with low-level structure types favored by modern vector and graphics processors.  The lack of multiple return values has a strong distorting effect on many Java APIs. Even if the JVM fails to unbox a value, there is still potential benefit to the value type.  Clustered computing systems something have copy operations (serialization or something similar) which apply implicitly to command operands.  When copying JVM objects, it is extremely helpful to know when an object’s identity is important or not.  If an object reference is a copied operand, the system may have to create a proxy handle which points back to the original object, so that side effects are visible.  Proxies must be managed carefully, and this can be expensive.  On the other hand, value types are exactly those types which a JVM can “copy and forget” with no downside. Array types are crucial to bulk data interfaces.  (As data sizes and rates increase, bulk data becomes more important than scalar data, so arrays are definitely accompanying us into the future of computing.)  Value types are very helpful for adding structure to bulk data, so a successful value type mechanism will make it easier for us to express richer forms of bulk data. Unboxing arrays (i.e., arrays containing unboxed values) will provide better cache and memory density, and more direct data movement within clustered or heterogeneous computing systems.  They require the deepest transformations, relative to today’s JVM.  There is an impedance mismatch between value-type arrays and Java’s covariant array typing, so compromises will need to be struck with existing Java semantics.  It is probably worth the effort, since arrays of unboxed value types are inherently more memory-efficient than standard Java arrays, which rely on dependent pointer chains. It may be sufficient to extend the “value-safe” concept to array declarations, and allow low-level transformations to change value-safe array declarations from the standard boxed form into an unboxed tuple-based form.  Such value-safe arrays would not be convertible to Object[] arrays.  Certain connection points, such as Arrays.copyOf and System.arraycopy might need additional input/output combinations, to allow smooth conversion between arrays with boxed and unboxed elements. Alternatively, the correct solution may have to wait until we have enough reification of generic types, and enough operator overloading, to enable an overhaul of Java arrays. Implicit Method Definitions The example of class Complex above may be unattractively complex.  I believe most or all of the elements of the example class are required by the logic of value types. If this is true, a programmer who writes a value type will have to write lots of error-prone boilerplate code.  On the other hand, I think nearly all of the code (except for the domain-specific parts like plus and minus) can be implicitly generated. Java has a rule for implicitly defining a class’s constructor, if no it defines no constructors explicitly.  Likewise, there are rules for providing default access modifiers for interface members.  Because of the highly regular structure of value types, it might be reasonable to perform similar implicit transformations on value types.  Here’s an example of a “highly implicit” definition of a complex number type: public class Complex implements ValueType {  // implicitly final     public double re, im;  // implicitly public final     //implicit methods are defined elementwise from te fields:     //  toString, asList, equals(2), hashCode, valueOf, cast     //optionally, explicit methods (plus, abs, etc.) would go here } In other words, with the right defaults, a simple value type definition can be a one-liner.  The observant reader will have noticed the similarities (and suitable differences) between the explicit methods above and the corresponding methods for List<T>. Another way to abbreviate such a class would be to make an annotation the primary trigger of the functionality, and to add the interface(s) implicitly: public @ValueType class Complex { … // implicitly final, implements ValueType (But to me it seems better to communicate the “magic” via an interface, even if it is rooted in an annotation.) Implicitly Defined Value Types So far we have been working with nominal value types, which is to say that the sequence of typed components is associated with a name and additional methods that convey the intention of the programmer.  A simple ordered pair of floating point numbers can be variously interpreted as (to name a few possibilities) a rectangular or polar complex number or Cartesian point.  The name and the methods convey the intended meaning. But what if we need a truly simple ordered pair of floating point numbers, without any further conceptual baggage?  Perhaps we are writing a method (like “divideAndRemainder”) which naturally returns a pair of numbers instead of a single number.  Wrapping the pair of numbers in a nominal type (like “QuotientAndRemainder”) makes as little sense as wrapping a single return value in a nominal type (like “Quotient”).  What we need here are structural value types commonly known as tuples. For the present discussion, let us assign a conventional, JVM-friendly name to tuples, roughly as follows: public class java.lang.tuple.$DD extends java.lang.tuple.Tuple {      double $1, $2; } Here the component names are fixed and all the required methods are defined implicitly.  The supertype is an abstract class which has suitable shared declarations.  The name itself mentions a JVM-style method parameter descriptor, which may be “cracked” to determine the number and types of the component fields. The odd thing about such a tuple type (and structural types in general) is it must be instantiated lazily, in response to linkage requests from one or more classes that need it.  The JVM and/or its class loaders must be prepared to spin a tuple type on demand, given a simple name reference, $xyz, where the xyz is cracked into a series of component types.  (Specifics of naming and name mangling need some tasteful engineering.) Tuples also seem to demand, even more than nominal types, some support from the language.  (This is probably because notations for non-nominal types work best as combinations of punctuation and type names, rather than named constructors like Function3 or Tuple2.)  At a minimum, languages with tuples usually (I think) have some sort of simple bracket notation for creating tuples, and a corresponding pattern-matching syntax (or “destructuring bind”) for taking tuples apart, at least when they are parameter lists.  Designing such a syntax is no simple thing, because it ought to play well with nominal value types, and also with pre-existing Java features, such as method parameter lists, implicit conversions, generic types, and reflection.  That is a task for another day. Other Use Cases Besides complex numbers and simple tuples there are many use cases for value types.  Many tuple-like types have natural value-type representations. These include rational numbers, point locations and pixel colors, and various kinds of dates and addresses. Other types have a variable-length ‘tail’ of internal values. The most common example of this is String, which is (mathematically) a sequence of UTF-16 character values. Similarly, bit vectors, multiple-precision numbers, and polynomials are composed of sequences of values. Such types include, in their representation, a reference to a variable-sized data structure (often an array) which (somehow) represents the sequence of values. The value type may also include ’header’ information. Variable-sized values often have a length distribution which favors short lengths. In that case, the design of the value type can make the first few values in the sequence be direct ’header’ fields of the value type. In the common case where the header is enough to represent the whole value, the tail can be a shared null value, or even just a null reference. Note that the tail need not be an immutable object, as long as the header type encapsulates it well enough. This is the case with String, where the tail is a mutable (but never mutated) character array. Field types and their order must be a globally visible part of the API.  The structure of the value type must be transparent enough to have a globally consistent unboxed representation, so that all callers and callees agree about the type and order of components  that appear as parameters, return types, and array elements.  This is a trade-off between efficiency and encapsulation, which is forced on us when we remove an indirection enjoyed by boxed representations.  A JVM-only transformation would not care about such visibility, but a bytecode transformation would need to take care that (say) the components of complex numbers would not get swapped after a redefinition of Complex and a partial recompile.  Perhaps constant pool references to value types need to declare the field order as assumed by each API user. This brings up the delicate status of private fields in a value type.  It must always be possible to load, store, and copy value types as coordinated groups, and the JVM performs those movements by moving individual scalar values between locals and stack.  If a component field is not public, what is to prevent hostile code from plucking it out of the tuple using a rogue aload or astore instruction?  Nothing but the verifier, so we may need to give it more smarts, so that it treats value types as inseparable groups of stack slots or locals (something like long or double). My initial thought was to make the fields always public, which would make the security problem moot.  But public is not always the right answer; consider the case of String, where the underlying mutable character array must be encapsulated to prevent security holes.  I believe we can win back both sides of the tradeoff, by training the verifier never to split up the components in an unboxed value.  Just as the verifier encapsulates the two halves of a 64-bit primitive, it can encapsulate the the header and body of an unboxed String, so that no code other than that of class String itself can take apart the values. Similar to String, we could build an efficient multi-precision decimal type along these lines: public final class DecimalValue extends ValueType {     protected final long header;     protected private final BigInteger digits;     public DecimalValue valueOf(int value, int scale) {         assert(scale >= 0);         return new DecimalValue(((long)value << 32) + scale, null);     }     public DecimalValue valueOf(long value, int scale) {         if (value == (int) value)             return valueOf((int)value, scale);         return new DecimalValue(-scale, new BigInteger(value));     } } Values of this type would be passed between methods as two machine words. Small values (those with a significand which fits into 32 bits) would be represented without any heap data at all, unless the DecimalValue itself were boxed. (Note the tension between encapsulation and unboxing in this case.  It would be better if the header and digits fields were private, but depending on where the unboxing information must “leak”, it is probably safer to make a public revelation of the internal structure.) Note that, although an array of Complex can be faked with a double-length array of double, there is no easy way to fake an array of unboxed DecimalValues.  (Either an array of boxed values or a transposed pair of homogeneous arrays would be reasonable fallbacks, in a current JVM.)  Getting the full benefit of unboxing and arrays will require some new JVM magic. Although the JVM emphasizes portability, system dependent code will benefit from using machine-level types larger than 64 bits.  For example, the back end of a linear algebra package might benefit from value types like Float4 which map to stock vector types.  This is probably only worthwhile if the unboxing arrays can be packed with such values. More Daydreams A more finely-divided design for dynamic enforcement of value safety could feature separate marker interfaces for each invariant.  An empty marker interface Unsynchronizable could cause suitable exceptions for monitor instructions on objects in marked classes.  More radically, a Interchangeable marker interface could cause JVM primitives that are sensitive to object identity to raise exceptions; the strangest result would be that the acmp instruction would have to be specified as raising an exception. @ValueSafe public interface ValueType extends java.io.Serializable,         Unsynchronizable, Interchangeable { … public class Complex implements ValueType {     // inherits Serializable, Unsynchronizable, Interchangeable, @ValueSafe     … It seems possible that Integer and the other wrapper types could be retro-fitted as value-safe types.  This is a major change, since wrapper objects would be unsynchronizable and their references interchangeable.  It is likely that code which violates value-safety for wrapper types exists but is uncommon.  It is less plausible to retro-fit String, since the prominent operation String.intern is often used with value-unsafe code. We should also reconsider the distinction between boxed and unboxed values in code.  The design presented above obscures that distinction.  As another thought experiment, we could imagine making a first class distinction in the type system between boxed and unboxed representations.  Since only primitive types are named with a lower-case initial letter, we could define that the capitalized version of a value type name always refers to the boxed representation, while the initial lower-case variant always refers to boxed.  For example: complex pi = complex.valueOf(Math.PI, 0); Complex boxPi = pi;  // convert to boxed myList.add(boxPi); complex z = myList.get(0);  // unbox Such a convention could perhaps absorb the current difference between int and Integer, double and Double. It might also allow the programmer to express a helpful distinction among array types. As said above, array types are crucial to bulk data interfaces, but are limited in the JVM.  Extending arrays beyond the present limitations is worth thinking about; for example, the Maxine JVM implementation has a hybrid object/array type.  Something like this which can also accommodate value type components seems worthwhile.  On the other hand, does it make sense for value types to contain short arrays?  And why should random-access arrays be the end of our design process, when bulk data is often sequentially accessed, and it might make sense to have heterogeneous streams of data as the natural “jumbo” data structure.  These considerations must wait for another day and another note. More Work It seems to me that a good sequence for introducing such value types would be as follows: Add the value-safety restrictions to an experimental version of javac. Code some sample applications with value types, including Complex and DecimalValue. Create an experimental JVM which internally unboxes value types but does not require new bytecodes to do so.  Ensure the feasibility of the performance model for the sample applications. Add tuple-like bytecodes (with or without generic type reification) to a major revision of the JVM, and teach the Java compiler to switch in the new bytecodes without code changes. A staggered roll-out like this would decouple language changes from bytecode changes, which is always a convenient thing. A similar investigation should be applied (concurrently) to array types.  In this case, it seems to me that the starting point is in the JVM: Add an experimental unboxing array data structure to a production JVM, perhaps along the lines of Maxine hybrids.  No bytecode or language support is required at first; everything can be done with encapsulated unsafe operations and/or method handles. Create an experimental JVM which internally unboxes value types but does not require new bytecodes to do so.  Ensure the feasibility of the performance model for the sample applications. Add tuple-like bytecodes (with or without generic type reification) to a major revision of the JVM, and teach the Java compiler to switch in the new bytecodes without code changes. That’s enough musing me for now.  Back to work!

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