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  • This Week in Geek History: Zelda Turns 25, Birth of the Printing Press, and the Unveiling of ENIAC

    - by Jason Fitzpatrick
    Every week we bring you interesting highlights from the history of geekdom. This week we take a look at The Legend of Zelda’s 25th anniversary, the Gutenberg press, and the unveiling of primitive super computer ENIAC. Latest Features How-To Geek ETC Should You Delete Windows 7 Service Pack Backup Files to Save Space? What Can Super Mario Teach Us About Graphics Technology? Windows 7 Service Pack 1 is Released: But Should You Install It? How To Make Hundreds of Complex Photo Edits in Seconds With Photoshop Actions How to Enable User-Specific Wireless Networks in Windows 7 How to Use Google Chrome as Your Default PDF Reader (the Easy Way) Reclaim Vertical UI Space by Moving Your Tabs to the Side in Firefox Wind and Water: Puzzle Battles – An Awesome Game for Linux and Windows How Star Wars Changed the World [Infographic] Tabs Visual Manager Adds Thumbnailed Tab Switching to Chrome Daisies and Rye Swaying in the Summer Wind Wallpaper Read On Phone Pushes Data from Your Desktop to the Appropriate Android App

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  • Finding a Relative Path in .NET

    - by Rick Strahl
    Here’s a nice and simple path utility that I’ve needed in a number of applications: I need to find a relative path based on a base path. So if I’m working in a folder called c:\temp\templates\ and I want to find a relative path for c:\temp\templates\subdir\test.txt I want to receive back subdir\test.txt. Or if I pass c:\ I want to get back ..\..\ – in other words always return a non-hardcoded path based on some other known directory. I’ve had a routine in my library that does this via some lengthy string parsing routines, but ran into some Uri processing today that made me realize that this code could be greatly simplified by using the System.Uri class instead. Here’s the simple static method: /// <summary> /// Returns a relative path string from a full path based on a base path /// provided. /// </summary> /// <param name="fullPath">The path to convert. Can be either a file or a directory</param> /// <param name="basePath">The base path on which relative processing is based. Should be a directory.</param> /// <returns> /// String of the relative path. /// /// Examples of returned values: /// test.txt, ..\test.txt, ..\..\..\test.txt, ., .., subdir\test.txt /// </returns> public static string GetRelativePath(string fullPath, string basePath ) { // ForceBasePath to a path if (!basePath.EndsWith("\\")) basePath += "\\"; Uri baseUri = new Uri(basePath); Uri fullUri = new Uri(fullPath); Uri relativeUri = baseUri.MakeRelativeUri(fullUri); // Uri's use forward slashes so convert back to backward slashes return relativeUri.ToString().Replace("/", "\\"); } You can then call it like this: string relPath = FileUtils.GetRelativePath("c:\temp\templates","c:\temp\templates\subdir\test.txt") It’s not exactly rocket science but it’s useful in many scenarios where you’re working with files based on an application base directory. Right now I’m working on a templating solution (using the Razor Engine) where templates live in a base directory and are supplied as relative paths to that base directory. Resolving these relative paths both ways is important in order to properly check for existance of files and their change status in this case. Not the kind of thing you use every day, but useful to remember.© Rick Strahl, West Wind Technologies, 2005-2010Posted in .NET  CSharp  

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  • AspNetCompatibility in WCF Services &ndash; easy to trip up

    - by Rick Strahl
    This isn’t the first time I’ve hit this particular wall: I’m creating a WCF REST service for AJAX callbacks and using the WebScriptServiceHostFactory host factory in the service: <%@ ServiceHost Language="C#" Service="WcfAjax.BasicWcfService" CodeBehind="BasicWcfService.cs" Factory="System.ServiceModel.Activation.WebScriptServiceHostFactory" %>   to avoid all configuration. Because of the Factory that creates the ASP.NET Ajax compatible format via the custom factory implementation I can then remove all of the configuration settings that typically get dumped into the web.config file. However, I do want ASP.NET compatibility so I still leave in: <system.serviceModel> <serviceHostingEnvironment aspNetCompatibilityEnabled="true"/> </system.serviceModel> in the web.config file. This option allows you access to the HttpContext.Current object to effectively give you access to most of the standard ASP.NET request and response features. This is not recommended as a primary practice but it can be useful in some scenarios and in backwards compatibility scenerios with ASP.NET AJAX Web Services. Now, here’s where things get funky. Assuming you have the setting in web.config, If you now declare a service like this: [ServiceContract(Namespace = "DevConnections")] #if DEBUG [ServiceBehavior(IncludeExceptionDetailInFaults = true)] #endif public class BasicWcfService (or by using an interface that defines the service contract) you’ll find that the service will not work when an AJAX call is made against it. You’ll get a 500 error and a System.ServiceModel.ServiceActivationException System error. Worse even with the IncludeExceptionDetailInFaults enabled you get absolutely no indication from WCF what the problem is. So what’s the problem?  The issue is that once you specify aspNetCompatibilityEnabled=”true” in the configuration you *have to* specify the AspNetCompatibilityRequirements attribute and one of the modes that enables or at least allows for it. You need either Required or Allow: [AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Required)] without it the service will simply fail without further warning. It will also fail if you set the attribute value to NotAllowed. The following also causes the service to fail as above: [AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.NotAllowed)] This is not totally unreasonable but it’s a difficult issue to debug especially since the configuration setting is global – if you have more than one service and one requires traditional ASP.NET access and one doesn’t then both must have the attribute specified. This is one reason why you’d want to avoid using this functionality unless absolutely necessary. WCF REST provides some basic access to some of the HTTP features after all, although what’s there is severely limited. I also wish that ServiceActivation errors would provide more error information. Getting an Activation error without further info on what actually is wrong is pretty worthless especially when it is a technicality like a mismatched configuration/attribute setting like this.© Rick Strahl, West Wind Technologies, 2005-2010Posted in ASP.NET  WCF  AJAX  

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  • SnagIt Live Writer Plug-in updated

    - by Rick Strahl
    I've updated my free SnagIt Live Writer plug-in again as there have been a few issues with the new release of SnagIt 11. It appears that TechSmith has trimmed the COM object and removed a bunch of redundant functionality which has broken the older plug-in. I also updated the layout and added SnagIt's latest icons to the form. Finally I've moved the source code to Github for easier browsing and downloading for anybody interested and easier updating for me. This plug-in is not new - I created it a number of years back, but I use the hell out it both for my blogging and for a few internal apps that with MetaWebLogApi to update online content. The plug-in makes it super easy to add captured image content directly into a post and upload it to the server. What does it do? Once installed the plug-in shows up in the list of plug-ins. When you click it launches a SnagIt Capture Dialog: Typically you set the capture settings once, and then save your settings. After that a single click or ENTER press gets you off capturing. If you choose the Show in SnagIt preview window option, the image you capture is is displayed in the preview editor to mark up images, which is one of SnagIt's great strengths IMHO. The image editor has a bunch of really nice effects for framing and marking up and highlighting of images that is really sweet. Here's a capture from a previous image in the SnagIt editor where I applied the saw tooth cutout effect: Images are saved to disk and can optionally be deleted immediately, since Live Writer creates copies of original images in its own folders before uploading the files. No need to keep the originals around typically. The plug-in works with SnagIt Versions 7 and later. It's a simple thing of course - nothing magic here, but incredibly useful at least to me. If you're using Live Writer and you own a copy of SnagIt do yourself a favor and grab this and install it as a plug-in. Resources: SnagIt Windows Live Writer Plug-in Installer Source Code on GitHub Buy SnagIt© Rick Strahl, West Wind Technologies, 2005-2012 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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  • A Small Utility to Delete Files recursively by Date

    - by Rick Strahl
    It's funny, but for me the following seems to be a recurring theme: Every few months or years I end up with a host of files on my server that need pruning selectively and often under program control. Today I realized that my SQL Server logs on my server were really piling up and nearly ran my backup drive out of drive space. So occasionally I need to check on that server drive and clean out files. Now with a bit of work this can be done with PowerShell or even a complicated DOS batch file, but heck, to me it's always easier to just create a small Console application that handles this sort of thing with a full command line parser and a few extra options, plus in the end I end up with code that I can actually modify and add features to as is invariably the case. No more searching for a script each time :-) So for my typical copy needs the requirements are: Need to recursively delete files Need to be able to specify a filespec (ie. *.bak) Be able to specify a cut off date before which to delete files And it'd be nice to have an option to send files to the Recycle bin just in case for operator error :-)(and yes that came in handy as I blew away my entire database backup folder by accident - oops!) The end result is a small Console file copy utility that I popped up on Github: https://github.com/RickStrahl/DeleteFiles The source code is up there along with the binary file you can just run. Creating DeleteFiles It's pretty easy to create a simple utility like DeleteFiles of course, so I'm not going to spend any talking about how it works. You can check it out in the repository or download and compile it. The nice thing about using a full programming language like C over something like PowerShell or batch file is that you can make short work of the recursive tree walking that's required to make this work. There's very little code, but there's also a very small, self-contained command line parser in there that might be useful that can be plugged into any project - I've been using it quite a bit for just about any Console application I've been building. If you're like me and don't have the patience or the persistence (that funky syntax requires some 'sticking with it' that I simply can't get over) to get into Powershell coding, having an executable file that I can just copy around or keep in my Utility directory is the only way I'll ever get to reuse this functionality without going on a wild search each time :-) Anyway, hope some of you might find this useful. © Rick Strahl, West Wind Technologies, 2005-2012Posted in Windows  CSharp   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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  • Nagios3: Conditional operators for service checks?

    - by Dave
    I'm trying to setup Nagios to monitor my various using hostgroups to define 'machine roles', against which I run services to check the machines by role. However, I'd like to use conditional operators that would enable me to run the service check against an intersection of two host groups, rather than their unions... i.e. using &&, ||, or () operators. For example, imagine I have the following servers: www-eu: Linux WWW (Apache) server, in the EU www-us: Windows WWW (IIS) server, in the US (West coast) ftp-eu: Linux FTP server, in the EU ftp-us: Windows FTP server, in the US I would want to create the following host groups: US-Servers: www-us, ftp-us EU-Servers: www-eu, ftp-eu WWW-Servers: www-us, www-eu FTP-Servers: ftp-us, ftp-eu Now say I'm interested in checking the HTTP response time for my web servers. Then let's say this particular Nagios service is running from the US (West Coast), and that I have a command called *check_http_response_time*. This command will check the responsiveness of the HTTP server, which I can provide an argument which defines the max response time before raising critical. My command might look like: check_http_response_time $HOSTNAME$ 50 Now traditionally, I can run my checks by specifying a list of host or hostgroups. define service{ use local-service hostgroup_name WWW-Servers # Servers = www-us, www-eu servicegroups WWW Checks service_description Check HTTP Response Time check_command check_http_response_time!50 } However, with the above service definition, given my Nagios service is in US West, I could reasonably expect that my EU server will return critical. Really, I want different thresholds for each region (50 for US West, 200 for EU.) I would have to permutate my service for each host and set their custom threshold, or alternatively permutate out my service groups by role & region (i.e. WWW-Servers-EU), and run my specific thresholds against those. Though the latter is better, both are much messier than I'd like... What I would love, and what this post is asking for, is a way to use hostgroups to perform an intersection using conditional logic, rather than a simple union. It might look like: define service{ use local-service hostgroup_name WWW-Servers && US-Servers servicegroups WWW Checks service_description Check HTTP Response Time check_command check_http_response_time!50 } It then would run the check only against servers that are in both WWW-Servers and US-Servers, in my example, just www-us. The benefits of such a feature would be significant for Nagios services configured for large-scale. Is this feature available? If it isn't, will it be available in the future? Is there an alternative way to accomplish this given the most recent Nagios version? Any tips/suggestions are most appreciated! Dave

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  • question on GWT and dockpanel , sizing and resizing

    - by molleman
    Hello guys, question on dock panels within gwt So i want the dockpanel to take up the whole size of the browser window dockPanel.setSize("100%", "100%"); if this correct Next Question, i am going to add a north panel , that will be 100px high and take up the whole width of the browser topPanel.setSize("100%", "100px"); dockPanel.add(topPanel, DockPanel.NORTH); is this correct, then i want to add a west panel that is 200px wide and the whole length of the browser up to just under the north panel westSideStackPanel.setSize("200px","100%") mainPanel.add(westSideStackPanel,DockPanel.WEST); i have created all this but when i look at my dockpanel there is a big gap between the west panel and the north panel the whole way accross the screen. why would this be? The north panel stays at 100px, and then there is a gap of about 100px high the whole width of the screen.

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  • php str_replace and \b word boundary

    - by Barry
    Hi, I am trying to use str_replace, but can't figure out how to use \b for word boundary: <?php $str = "East Northeast winds 20 knots"; $search = array("North", "North Northeast", "Northeast", "East Northeast", "East", "East Southeast", "SouthEast", "South Southeast", "South", "South Southwest", "Southwest", "West Southwest", "West", "West Northwest", "Northwest", "North Northwest"); $replace = array("N", "NNE", "NE", "ENE", "E", "ESE", "SE", "SSE", "S", "SSW", "SW", "WSW", "W", "WNW", "NW", "NNW"); $abbr = str_replace($search, $replace, $str); echo $abbr; // this example echoes "E Neast winds 20 knots" since \b word boundary is not used // how to apply word boundary so that is seeks the exact words to replace? // the text to replace could be anywhere (start, middle, end) of string // this example should output "ENE winds 20 knots" ?>

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  • Different ways to query this search in SQL?

    - by Bart Terrell
    I am teaching myself MS-SQL and I am trying to find different ways to find the Count of Paid and Unpaid Claims for 2012 grouped by Region from these 3 tables. If there is a returned date, the claim is unpaid if the returned date is null then the claim is paid. I will attach the code I have ran, but I am not sure if there are better ways to do it. Thanks. Here is the code: SET dateformat ymd; CREATE TABLE Claims ( ClaimID INT, SubID INT, [Claim Date] DATETIME ); CREATE TABLE Phoneship ( ClaimID INT, [Shipping Number] INT, [Claim Date] DATETIME, [Ship Date] DATETIME, [Returned Date] DATETIME ); CREATE TABLE Enrollment ( SubID INT, Enrollment_Date DATETIME, Channel NVARCHAR(255), Region NVARCHAR(255), Status FLOAT, Drop_Date DATETIME ); INSERT INTO [Phoneship] ([ClaimID], [Shipping Number], [Claim Date], [Ship Date], [Returned Date]) VALUES (102, 201, '2011-10-13 00:00:00', '2011-10-14 00:00:00', NULL); INSERT INTO [Phoneship] ([ClaimID], [Shipping Number], [Claim Date], [Ship Date], [Returned Date]) VALUES (103, 202, '2011-11-02 00:00:00', '2011-11-03 00:00:00', '2011-11-20 00:00:00'); INSERT INTO [Phoneship] ([ClaimID], [Shipping Number], [Claim Date], [Ship Date], [Returned Date]) VALUES (103, 203, '2011-11-02 00:00:00', '2011-11-22 00:00:00', NULL); INSERT INTO [Phoneship] ([ClaimID], [Shipping Number], [Claim Date], [Ship Date], [Returned Date]) VALUES (105, 204, '2012-01-16 00:00:00', '2012-01-17 00:00:00', NULL); INSERT INTO [Phoneship] ([ClaimID], [Shipping Number], [Claim Date], [Ship Date], [Returned Date]) VALUES (106, 205, '2012-02-15 00:00:00', '2012-02-16 00:00:00', '2012-02-26 00:00:00'); INSERT INTO [Phoneship] ([ClaimID], [Shipping Number], [Claim Date], [Ship Date], [Returned Date]) VALUES (106, 206, '2012-02-15 00:00:00', '2012-02-27 00:00:00', '2012-03-06 00:00:00'); INSERT INTO [Phoneship] ([ClaimID], [Shipping Number], [Claim Date], [Ship Date], [Returned Date]) VALUES (107, 207, '2012-03-12 00:00:00', '2012-03-13 00:00:00', NULL); INSERT INTO [Phoneship] ([ClaimID], [Shipping Number], [Claim Date], [Ship Date], [Returned Date]) VALUES (108, 208, '2012-05-11 00:00:00', '2012-05-12 00:00:00', NULL); INSERT INTO [Phoneship] ([ClaimID], [Shipping Number], [Claim Date], [Ship Date], [Returned Date]) VALUES (109, 209, '2012-05-13 00:00:00', '2012-05-14 00:00:00', '2012-05-28 00:00:00'); INSERT INTO [Phoneship] ([ClaimID], [Shipping Number], [Claim Date], [Ship Date], [Returned Date]) VALUES (109, 210, '2012-05-13 00:00:00', '2012-05-30 00:00:00', NULL); INSERT INTO [Claims] ([ClaimID], [SubID], [Claim Date]) VALUES (101, 12345678, '2011-03-06 00:00:00'); INSERT INTO [Claims] ([ClaimID], [SubID], [Claim Date]) VALUES (102, 12347190, '2011-10-13 00:00:00'); INSERT INTO [Claims] ([ClaimID], [SubID], [Claim Date]) VALUES (103, 12348723, '2011-11-02 00:00:00'); INSERT INTO [Claims] ([ClaimID], [SubID], [Claim Date]) VALUES (104, 12349745, '2011-11-09 00:00:00'); INSERT INTO [Claims] ([ClaimID], [SubID], [Claim Date]) VALUES (105, 12347190, '2012-01-16 00:00:00'); INSERT INTO [Claims] ([ClaimID], [SubID], [Claim Date]) VALUES (106, 12349234, '2012-02-15 00:00:00'); INSERT INTO [Claims] ([ClaimID], [SubID], [Claim Date]) VALUES (107, 12350767, '2012-03-12 00:00:00'); INSERT INTO [Claims] ([ClaimID], [SubID], [Claim Date]) VALUES (108, 12350256, '2012-05-11 00:00:00'); INSERT INTO [Claims] ([ClaimID], [SubID], [Claim Date]) VALUES (109, 12347701, '2012-05-13 00:00:00'); INSERT INTO [Claims] ([ClaimID], [SubID], [Claim Date]) VALUES (110, 12350256, '2012-05-15 00:00:00'); INSERT INTO [Claims] ([ClaimID], [SubID], [Claim Date]) VALUES (111, 12350767, '2012-06-30 00:00:00'); INSERT INTO [Enrollment] ([SubID], [Enrollment_Date], [Channel], [Region], [Status], [Drop_Date]) VALUES (12345678, '2011-01-05 00:00:00', 'Retail', 'Southeast', 1, NULL); INSERT INTO [Enrollment] ([SubID], [Enrollment_Date], [Channel], [Region], [Status], [Drop_Date]) VALUES (12346178, '2011-03-13 00:00:00', 'Indirect Dealers', 'West', 1, NULL); INSERT INTO [Enrollment] ([SubID], [Enrollment_Date], [Channel], [Region], [Status], [Drop_Date]) VALUES (12346679, '2011-05-19 00:00:00', 'Indirect Dealers', 'Southeast', 0, '2012-03-15 00:00:00'); INSERT INTO [Enrollment] ([SubID], [Enrollment_Date], [Channel], [Region], [Status], [Drop_Date]) VALUES (12347190, '2011-07-25 00:00:00', 'Retail', 'Northeast', 0, '2012-05-21 00:00:00'); INSERT INTO [Enrollment] ([SubID], [Enrollment_Date], [Channel], [Region], [Status], [Drop_Date]) VALUES (12347701, '2011-08-14 00:00:00', 'Indirect Dealers', 'West', 1, NULL); INSERT INTO [Enrollment] ([SubID], [Enrollment_Date], [Channel], [Region], [Status], [Drop_Date]) VALUES (12348212, '2011-09-30 00:00:00', 'Retail', 'West', 1, NULL); INSERT INTO [Enrollment] ([SubID], [Enrollment_Date], [Channel], [Region], [Status], [Drop_Date]) VALUES (12348723, '2011-10-20 00:00:00', 'Retail', 'Southeast', 1, NULL); INSERT INTO [Enrollment] ([SubID], [Enrollment_Date], [Channel], [Region], [Status], [Drop_Date]) VALUES (12349234, '2012-01-06 00:00:00', 'Indirect Dealers', 'West', 0, '2012-02-14 00:00:00'); INSERT INTO [Enrollment] ([SubID], [Enrollment_Date], [Channel], [Region], [Status], [Drop_Date]) VALUES (12349745, '2012-01-26 00:00:00', 'Retail', 'Northeast', 0, '2012-04-15 00:00:00'); INSERT INTO [Enrollment] ([SubID], [Enrollment_Date], [Channel], [Region], [Status], [Drop_Date]) VALUES (12350256, '2012-02-11 00:00:00', 'Retail', 'Southeast', 1, NULL); INSERT INTO [Enrollment] ([SubID], [Enrollment_Date], [Channel], [Region], [Status], [Drop_Date]) VALUES (12350767, '2012-03-02 00:00:00', 'Indirect Dealers', 'West', 1, NULL); INSERT INTO [Enrollment] ([SubID], [Enrollment_Date], [Channel], [Region], [Status], [Drop_Date]) VALUES (12351278, '2012-04-18 00:00:00', 'Retail', 'Midwest', 1, NULL); INSERT INTO [Enrollment] ([SubID], [Enrollment_Date], [Channel], [Region], [Status], [Drop_Date]) VALUES (12351789, '2012-05-08 00:00:00', 'Indirect Dealers', 'West', 0, '2012-07-04 00:00:00'); INSERT INTO [Enrollment] ([SubID], [Enrollment_Date], [Channel], [Region], [Status], [Drop_Date]) VALUES (12352300, '2012-06-24 00:00:00', 'Retail', 'Midwest', 1, NULL); INSERT INTO [Enrollment] ([SubID], [Enrollment_Date], [Channel], [Region], [Status], [Drop_Date]) VALUES (12352811, '2012-06-25 00:00:00', 'Retail', 'Southeast', 1, NULL); And Query1 SELECT Count(ClaimID) AS 'Paid Claim', (SELECT Count(ClaimID) FROM dbo.phoneship WHERE [returned date] IS NOT NULL) AS 'Unpaid Claim' FROM dbo.Phoneship WHERE [Returned Date] IS NULL GROUP BY claimid Query2 SELECT Count(*) AS 'Paid Claims', (SELECT Count(*) FROM dbo.Phoneship WHERE [Returned Date] IS NOT NULL) AS 'Unpaid Claims' FROM dbo.Phoneship WHERE [Returned Date] IS NULL; Query3 Select Distinct(C.[Shipping Number]), Count(C.ClaimID) AS 'COUNT ClaimID', A.Region, A.SubID From dbo.HSEnrollment A Inner Join dbo.Claims B On A.SubId = B.SubId Inner Join dbo.Phoneship C On B.ClaimID = C.ClaimID Where C.[Returned Date] IS NULL Group By A.Region, A.Subid, C.ClaimID, C.[Shipping Number] Order By A.Region

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  • Calculating the union of 2 longitudal intervals (that may wrap around 180 degrees)

    - by timpatt
    The story: I have a LatLongBounds class that represents an area on the surface of the earth by a latitudinal interval (bounded by north & south - not important to this question) and a longitudinal interval (bounded by east and west; both normalized to a range [-180, 180] - negative being a westerly direction). In order to be able to represent an area that straddles the 180 degree meridian the value of west may be set to be greater than east (eg. the range west = 170, east = -170 will straddle said meridian). In effect the longitudinal interval may wrap around at 180 degrees (or equivalently -180 degrees). My Question: Does anyone have any suggestions as to how I can calculate the union of two longitudinal intervals that may wrap around at 180 degrees. Thanks.

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  • What&rsquo;s New in ASP.NET 4.0 Part Two: WebForms and Visual Studio Enhancements

    - by Rick Strahl
    In the last installment I talked about the core changes in the ASP.NET runtime that I’ve been taking advantage of. In this column, I’ll cover the changes to the Web Forms engine and some of the cool improvements in Visual Studio that make Web and general development easier. WebForms The WebForms engine is the area that has received most significant changes in ASP.NET 4.0. Probably the most widely anticipated features are related to managing page client ids and of ViewState on WebForm pages. Take Control of Your ClientIDs Unique ClientID generation in ASP.NET has been one of the most complained about “features” in ASP.NET. Although there’s a very good technical reason for these unique generated ids - they guarantee unique ids for each and every server control on a page - these unique and generated ids often get in the way of client-side JavaScript development and CSS styling as it’s often inconvenient and fragile to work with the long, generated ClientIDs. In ASP.NET 4.0 you can now specify an explicit client id mode on each control or each naming container parent control to control how client ids are generated. By default, ASP.NET generates mangled client ids for any control contained in a naming container (like a Master Page, or a User Control for example). The key to ClientID management in ASP.NET 4.0 are the new ClientIDMode and ClientIDRowSuffix properties. ClientIDMode supports four different ClientID generation settings shown below. For the following examples, imagine that you have a Textbox control named txtName inside of a master page control container on a WebForms page. <%@Page Language="C#"      MasterPageFile="~/Site.Master"     CodeBehind="WebForm2.aspx.cs"     Inherits="WebApplication1.WebForm2"  %> <asp:Content ID="content"  ContentPlaceHolderID="content"               runat="server"               ClientIDMode="Static" >       <asp:TextBox runat="server" ID="txtName" /> </asp:Content> The four available ClientIDMode values are: AutoID This is the existing behavior in ASP.NET 1.x-3.x where full naming container munging takes place. <input name="ctl00$content$txtName" type="text"        id="ctl00_content_txtName" /> This should be familiar to any ASP.NET developer and results in fairly unpredictable client ids that can easily change if the containership hierarchy changes. For example, removing the master page changes the name in this case, so if you were to move a block of script code that works against the control to a non-Master page, the script code immediately breaks. Static This option is the most deterministic setting that forces the control’s ClientID to use its ID value directly. No naming container naming at all is applied and you end up with clean client ids: <input name="ctl00$content$txtName"         type="text" id="txtName" /> Note that the name property which is used for postback variables to the server still is munged, but the ClientID property is displayed simply as the ID value that you have assigned to the control. This option is what most of us want to use, but you have to be clear on that because it can potentially cause conflicts with other controls on the page. If there are several instances of the same naming container (several instances of the same user control for example) there can easily be a client id naming conflict. Note that if you assign Static to a data-bound control, like a list child control in templates, you do not get unique ids either, so for list controls where you rely on unique id for child controls, you’ll probably want to use Predictable rather than Static. I’ll write more on this a little later when I discuss ClientIDRowSuffix. Predictable The previous two values are pretty self-explanatory. Predictable however, requires some explanation. To me at least it’s not in the least bit predictable. MSDN defines this value as follows: This algorithm is used for controls that are in data-bound controls. The ClientID value is generated by concatenating the ClientID value of the parent naming container with the ID value of the control. If the control is a data-bound control that generates multiple rows, the value of the data field specified in the ClientIDRowSuffix property is added at the end. For the GridView control, multiple data fields can be specified. If the ClientIDRowSuffix property is blank, a sequential number is added at the end instead of a data-field value. Each segment is separated by an underscore character (_). The key that makes this value a bit confusing is that it relies on the parent NamingContainer’s ClientID to build its own ClientID value. This effectively means that the value is not predictable at all but rather very tightly coupled to the parent naming container’s ClientIDMode setting. For my simple textbox example, if the ClientIDMode property of the parent naming container (Page in this case) is set to “Predictable” you’ll get this: <input name="ctl00$content$txtName" type="text"         id="content_txtName" /> which gives an id that based on walking up to the currently active naming container (the MasterPage content container) and starting the id formatting from there downward. Think of this as a semi unique name that’s guaranteed unique only for the naming container. If, on the other hand, the Page is set to “AutoID” you get the following with Predictable on txtName: <input name="ctl00$content$txtName" type="text"         id="ctl00_content_txtName" /> The latter is effectively the same as if you specified AutoID because it inherits the AutoID naming from the Page and Content Master Page control of the page. But again - predictable behavior always depends on the parent naming container and how it generates its id, so the id may not always be exactly the same as the AutoID generated value because somewhere in the NamingContainer chain the ClientIDMode setting may be set to a different value. For example, if you had another naming container in the middle that was set to Static you’d end up effectively with an id that starts with the NamingContainers id rather than the whole ctl000_content munging. The most common use for Predictable is likely to be for data-bound controls, which results in each data bound item getting a unique ClientID. Unfortunately, even here the behavior can be very unpredictable depending on which data-bound control you use - I found significant differences in how template controls in a GridView behave from those that are used in a ListView control. For example, GridView creates clean child ClientIDs, while ListView still has a naming container in the ClientID, presumably because of the template container on which you can’t set ClientIDMode. Predictable is useful, but only if all naming containers down the chain use this setting. Otherwise you’re right back to the munged ids that are pretty unpredictable. Another property, ClientIDRowSuffix, can be used in combination with ClientIDMode of Predictable to force a suffix onto list client controls. For example: <asp:GridView runat="server" ID="gvItems"              AutoGenerateColumns="false"             ClientIDMode="Static"              ClientIDRowSuffix="Id">     <Columns>     <asp:TemplateField>         <ItemTemplate>             <asp:Label runat="server" id="txtName"                        Text='<%# Eval("Name") %>'                   ClientIDMode="Predictable"/>         </ItemTemplate>     </asp:TemplateField>     <asp:TemplateField>         <ItemTemplate>         <asp:Label runat="server" id="txtId"                     Text='<%# Eval("Id") %>'                     ClientIDMode="Predictable" />         </ItemTemplate>     </asp:TemplateField>     </Columns>  </asp:GridView> generates client Ids inside of a column in the master page described earlier: <td>     <span id="txtName_0">Rick</span> </td> where the value after the underscore is the ClientIDRowSuffix field - in this case “Id” of the item data bound to the control. Note that all of the child controls require ClientIDMode=”Predictable” in order for the ClientIDRowSuffix to be applied, and the parent GridView controls need to be set to Static either explicitly or via Naming Container inheritance to give these simple names. It’s a bummer that ClientIDRowSuffix doesn’t work with Static to produce this automatically. Another real problem is that other controls process the ClientIDMode differently. For example, a ListView control processes the Predictable ClientIDMode differently and produces the following with the Static ListView and Predictable child controls: <span id="ctrl0_txtName_0">Rick</span> I couldn’t even figure out a way using ClientIDMode to get a simple ID that also uses a suffix short of falling back to manually generated ids using <%= %> expressions instead. Given the inconsistencies inside of list controls using <%= %>, ids for the ListView might not be a bad idea anyway. Inherit The final setting is Inherit, which is the default for all controls except Page. This means that controls by default inherit the parent naming container’s ClientIDMode setting. For more detailed information on ClientID behavior and different scenarios you can check out a blog post of mine on this subject: http://www.west-wind.com/weblog/posts/54760.aspx. ClientID Enhancements Summary The ClientIDMode property is a welcome addition to ASP.NET 4.0. To me this is probably the most useful WebForms feature as it allows me to generate clean IDs simply by setting ClientIDMode="Static" on either the page or inside of Web.config (in the Pages section) which applies the setting down to the entire page which is my 95% scenario. For the few cases when it matters - for list controls and inside of multi-use user controls or custom server controls) - I can use Predictable or even AutoID to force controls to unique names. For application-level page development, this is easy to accomplish and provides maximum usability for working with client script code against page controls. ViewStateMode Another area of large criticism for WebForms is ViewState. ViewState is used internally by ASP.NET to persist page-level changes to non-postback properties on controls as pages post back to the server. It’s a useful mechanism that works great for the overall mechanics of WebForms, but it can also cause all sorts of overhead for page operation as ViewState can very quickly get out of control and consume huge amounts of bandwidth in your page content. ViewState can also wreak havoc with client-side scripting applications that modify control properties that are tracked by ViewState, which can produce very unpredictable results on a Postback after client-side updates. Over the years in my own development, I’ve often turned off ViewState on pages to reduce overhead. Yes, you lose some functionality, but you can easily implement most of the common functionality in non-ViewState workarounds. Relying less on heavy ViewState controls and sticking with simpler controls or raw HTML constructs avoids getting around ViewState problems. In ASP.NET 3.x and prior, it wasn’t easy to control ViewState - you could turn it on or off and if you turned it off at the page or web.config level, you couldn’t turn it back on for specific controls. In short, it was an all or nothing approach. With ASP.NET 4.0, the new ViewStateMode property gives you more control. It allows you to disable ViewState globally either on the page or web.config level and then turn it back on for specific controls that might need it. ViewStateMode only works when EnableViewState="true" on the page or web.config level (which is the default). You can then use ViewStateMode of Disabled, Enabled or Inherit to control the ViewState settings on the page. If you’re shooting for minimal ViewState usage, the ideal situation is to set ViewStateMode to disabled on the Page or web.config level and only turn it back on particular controls: <%@Page Language="C#"      CodeBehind="WebForm2.aspx.cs"     Inherits="Westwind.WebStore.WebForm2"        ClientIDMode="Static"                ViewStateMode="Disabled"     EnableViewState="true"  %> <!-- this control has viewstate  --> <asp:TextBox runat="server" ID="txtName"  ViewStateMode="Enabled" />       <!-- this control has no viewstate - it inherits  from parent container --> <asp:TextBox runat="server" ID="txtAddress" /> Note that the EnableViewState="true" at the Page level isn’t required since it’s the default, but it’s important that the value is true. ViewStateMode has no effect if EnableViewState="false" at the page level. The main benefit of ViewStateMode is that it allows you to more easily turn off ViewState for most of the page and enable only a few key controls that might need it. For me personally, this is a perfect combination as most of my WebForm apps can get away without any ViewState at all. But some controls - especially third party controls - often don’t work well without ViewState enabled, and now it’s much easier to selectively enable controls rather than the old way, which required you to pretty much turn off ViewState for all controls that you didn’t want ViewState on. Inline HTML Encoding HTML encoding is an important feature to prevent cross-site scripting attacks in data entered by users on your site. In order to make it easier to create HTML encoded content, ASP.NET 4.0 introduces a new Expression syntax using <%: %> to encode string values. The encoding expression syntax looks like this: <%: "<script type='text/javascript'>" +     "alert('Really?');</script>" %> which produces properly encoded HTML: &lt;script type=&#39;text/javascript&#39; &gt;alert(&#39;Really?&#39;);&lt;/script&gt; Effectively this is a shortcut to: <%= HttpUtility.HtmlEncode( "<script type='text/javascript'>" + "alert('Really?');</script>") %> Of course the <%: %> syntax can also evaluate expressions just like <%= %> so the more common scenario applies this expression syntax against data your application is displaying. Here’s an example displaying some data model values: <%: Model.Address.Street %> This snippet shows displaying data from your application’s data store or more importantly, from data entered by users. Anything that makes it easier and less verbose to HtmlEncode text is a welcome addition to avoid potential cross-site scripting attacks. Although I listed Inline HTML Encoding here under WebForms, anything that uses the WebForms rendering engine including ASP.NET MVC, benefits from this feature. ScriptManager Enhancements The ASP.NET ScriptManager control in the past has introduced some nice ways to take programmatic and markup control over script loading, but there were a number of shortcomings in this control. The ASP.NET 4.0 ScriptManager has a number of improvements that make it easier to control script loading and addresses a few of the shortcomings that have often kept me from using the control in favor of manual script loading. The first is the AjaxFrameworkMode property which finally lets you suppress loading the ASP.NET AJAX runtime. Disabled doesn’t load any ASP.NET AJAX libraries, but there’s also an Explicit mode that lets you pick and choose the library pieces individually and reduce the footprint of ASP.NET AJAX script included if you are using the library. There’s also a new EnableCdn property that forces any script that has a new WebResource attribute CdnPath property set to a CDN supplied URL. If the script has this Attribute property set to a non-null/empty value and EnableCdn is enabled on the ScriptManager, that script will be served from the specified CdnPath. [assembly: WebResource(    "Westwind.Web.Resources.ww.jquery.js",    "application/x-javascript",    CdnPath =  "http://mysite.com/scripts/ww.jquery.min.js")] Cool, but a little too static for my taste since this value can’t be changed at runtime to point at a debug script as needed, for example. Assembly names for loading scripts from resources can now be simple names rather than fully qualified assembly names, which make it less verbose to reference scripts from assemblies loaded from your bin folder or the assembly reference area in web.config: <asp:ScriptManager runat="server" id="Id"          EnableCdn="true"         AjaxFrameworkMode="disabled">     <Scripts>         <asp:ScriptReference          Name="Westwind.Web.Resources.ww.jquery.js"         Assembly="Westwind.Web" />     </Scripts>        </asp:ScriptManager> The ScriptManager in 4.0 also supports script combining via the CompositeScript tag, which allows you to very easily combine scripts into a single script resource served via ASP.NET. Even nicer: You can specify the URL that the combined script is served with. Check out the following script manager markup that combines several static file scripts and a script resource into a single ASP.NET served resource from a static URL (allscripts.js): <asp:ScriptManager runat="server" id="Id"          EnableCdn="true"         AjaxFrameworkMode="disabled">     <CompositeScript          Path="~/scripts/allscripts.js">         <Scripts>             <asp:ScriptReference                    Path="~/scripts/jquery.js" />             <asp:ScriptReference                    Path="~/scripts/ww.jquery.js" />             <asp:ScriptReference            Name="Westwind.Web.Resources.editors.js"                 Assembly="Westwind.Web" />         </Scripts>     </CompositeScript> </asp:ScriptManager> When you render this into HTML, you’ll see a single script reference in the page: <script src="scripts/allscripts.debug.js"          type="text/javascript"></script> All you need to do to make this work is ensure that allscripts.js and allscripts.debug.js exist in the scripts folder of your application - they can be empty but the file has to be there. This is pretty cool, but you want to be real careful that you use unique URLs for each combination of scripts you combine or else browser and server caching will easily screw you up royally. The script manager also allows you to override native ASP.NET AJAX scripts now as any script references defined in the Scripts section of the ScriptManager trump internal references. So if you want custom behavior or you want to fix a possible bug in the core libraries that normally are loaded from resources, you can now do this simply by referencing the script resource name in the Name property and pointing at System.Web for the assembly. Not a common scenario, but when you need it, it can come in real handy. Still, there are a number of shortcomings in this control. For one, the ScriptManager and ClientScript APIs still have no common entry point so control developers are still faced with having to check and support both APIs to load scripts so that controls can work on pages that do or don’t have a ScriptManager on the page. The CdnUrl is static and compiled in, which is very restrictive. And finally, there’s still no control over where scripts get loaded on the page - ScriptManager still injects scripts into the middle of the HTML markup rather than in the header or optionally the footer. This, in turn, means there is little control over script loading order, which can be problematic for control developers. MetaDescription, MetaKeywords Page Properties There are also a number of additional Page properties that correspond to some of the other features discussed in this column: ClientIDMode, ClientTarget and ViewStateMode. Another minor but useful feature is that you can now directly access the MetaDescription and MetaKeywords properties on the Page object to set the corresponding meta tags programmatically. Updating these values programmatically previously required either <%= %> expressions in the page markup or dynamic insertion of literal controls into the page. You can now just set these properties programmatically on the Page object in any Control derived class on the page or the Page itself: Page.MetaKeywords = "ASP.NET,4.0,New Features"; Page.MetaDescription = "This article discusses the new features in ASP.NET 4.0"; Note, that there’s no corresponding ASP.NET tag for the HTML Meta element, so the only way to specify these values in markup and access them is via the @Page tag: <%@Page Language="C#"      CodeBehind="WebForm2.aspx.cs"     Inherits="Westwind.WebStore.WebForm2"      ClientIDMode="Static"                MetaDescription="Article that discusses what's                      new in ASP.NET 4.0"     MetaKeywords="ASP.NET,4.0,New Features" %> Nothing earth shattering but quite convenient. Visual Studio 2010 Enhancements for Web Development For Web development there are also a host of editor enhancements in Visual Studio 2010. Some of these are not Web specific but they are useful for Web developers in general. Text Editors Throughout Visual Studio 2010, the text editors have all been updated to a new core engine based on WPF which provides some interesting new features for various code editors including the nice ability to zoom in and out with Ctrl-MouseWheel to quickly change the size of text. There are many more API options to control the editor and although Visual Studio 2010 doesn’t yet use many of these features, we can look forward to enhancements in add-ins and future editor updates from the various language teams that take advantage of the visual richness that WPF provides to editing. On the negative side, I’ve noticed that occasionally the code editor and especially the HTML and JavaScript editors will lose the ability to use various navigation keys like arrows, back and delete keys, which requires closing and reopening the documents at times. This issue seems to be well documented so I suspect this will be addressed soon with a hotfix or within the first service pack. Overall though, the code editors work very well, especially given that they were re-written completely using WPF, which was one of my big worries when I first heard about the complete redesign of the editors. Multi-Targeting Visual Studio now targets all versions of the .NET framework from 2.0 forward. You can use Visual Studio 2010 to work on your ASP.NET 2, 3.0 and 3.5 applications which is a nice way to get your feet wet with the new development environment without having to make changes to existing applications. It’s nice to have one tool to work in for all the different versions. Multi-Monitor Support One cool feature of Visual Studio 2010 is the ability to drag windows out of the Visual Studio environment and out onto the desktop including onto another monitor easily. Since Web development often involves working with a host of designers at the same time - visual designer, HTML markup window, code behind and JavaScript editor - it’s really nice to be able to have a little more screen real estate to work on each of these editors. Microsoft made a welcome change in the environment. IntelliSense Snippets for HTML and JavaScript Editors The HTML and JavaScript editors now finally support IntelliSense scripts to create macro-based template expansions that have been in the core C# and Visual Basic code editors since Visual Studio 2005. Snippets allow you to create short XML-based template definitions that can act as static macros or real templates that can have replaceable values that can be embedded into the expanded text. The XML syntax for these snippets is straight forward and it’s pretty easy to create custom snippets manually. You can easily create snippets using XML and store them in your custom snippets folder (C:\Users\rstrahl\Documents\Visual Studio 2010\Code Snippets\Visual Web Developer\My HTML Snippets and My JScript Snippets), but it helps to use one of the third-party tools that exist to simplify the process for you. I use SnippetEditor, by Bill McCarthy, which makes short work of creating snippets interactively (http://snippeteditor.codeplex.com/). Note: You may have to manually add the Visual Studio 2010 User specific Snippet folders to this tool to see existing ones you’ve created. Code snippets are some of the biggest time savers and HTML editing more than anything deals with lots of repetitive tasks that lend themselves to text expansion. Visual Studio 2010 includes a slew of built-in snippets (that you can also customize!) and you can create your own very easily. If you haven’t done so already, I encourage you to spend a little time examining your coding patterns and find the repetitive code that you write and convert it into snippets. I’ve been using CodeRush for this for years, but now you can do much of the basic expansion natively for HTML and JavaScript snippets. jQuery Integration Is Now Native jQuery is a popular JavaScript library and recently Microsoft has recently stated that it will become the primary client-side scripting technology to drive higher level script functionality in various ASP.NET Web projects that Microsoft provides. In Visual Studio 2010, the default full project template includes jQuery as part of a new project including the support files that provide IntelliSense (-vsdoc files). IntelliSense support for jQuery is now also baked into Visual Studio 2010, so unlike Visual Studio 2008 which required a separate download, no further installs are required for a rich IntelliSense experience with jQuery. Summary ASP.NET 4.0 brings many useful improvements to the platform, but thankfully most of the changes are incremental changes that don’t compromise backwards compatibility and they allow developers to ease into the new features one feature at a time. None of the changes in ASP.NET 4.0 or Visual Studio 2010 are monumental or game changers. The bigger features are language and .NET Framework changes that are also optional. This ASP.NET and tools release feels more like fine tuning and getting some long-standing kinks worked out of the platform. It shows that the ASP.NET team is dedicated to paying attention to community feedback and responding with changes to the platform and development environment based on this feedback. If you haven’t gotten your feet wet with ASP.NET 4.0 and Visual Studio 2010, there’s no reason not to give it a shot now - the ASP.NET 4.0 platform is solid and Visual Studio 2010 works very well for a brand new release. Check it out. © Rick Strahl, West Wind Technologies, 2005-2010Posted in ASP.NET  

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  • An Xml Serializable PropertyBag Dictionary Class for .NET

    - by Rick Strahl
    I don't know about you but I frequently need property bags in my applications to store and possibly cache arbitrary data. Dictionary<T,V> works well for this although I always seem to be hunting for a more specific generic type that provides a string key based dictionary. There's string dictionary, but it only works with strings. There's Hashset<T> but it uses the actual values as keys. In most key value pair situations for me string is key value to work off. Dictionary<T,V> works well enough, but there are some issues with serialization of dictionaries in .NET. The .NET framework doesn't do well serializing IDictionary objects out of the box. The XmlSerializer doesn't support serialization of IDictionary via it's default serialization, and while the DataContractSerializer does support IDictionary serialization it produces some pretty atrocious XML. What doesn't work? First off Dictionary serialization with the Xml Serializer doesn't work so the following fails: [TestMethod] public void DictionaryXmlSerializerTest() { var bag = new Dictionary<string, object>(); bag.Add("key", "Value"); bag.Add("Key2", 100.10M); bag.Add("Key3", Guid.NewGuid()); bag.Add("Key4", DateTime.Now); bag.Add("Key5", true); bag.Add("Key7", new byte[3] { 42, 45, 66 }); TestContext.WriteLine(this.ToXml(bag)); } public string ToXml(object obj) { if (obj == null) return null; StringWriter sw = new StringWriter(); XmlSerializer ser = new XmlSerializer(obj.GetType()); ser.Serialize(sw, obj); return sw.ToString(); } The error you get with this is: System.NotSupportedException: The type System.Collections.Generic.Dictionary`2[[System.String, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089],[System.Object, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]] is not supported because it implements IDictionary. Got it! BTW, the same is true with binary serialization. Running the same code above against the DataContractSerializer does work: [TestMethod] public void DictionaryDataContextSerializerTest() { var bag = new Dictionary<string, object>(); bag.Add("key", "Value"); bag.Add("Key2", 100.10M); bag.Add("Key3", Guid.NewGuid()); bag.Add("Key4", DateTime.Now); bag.Add("Key5", true); bag.Add("Key7", new byte[3] { 42, 45, 66 }); TestContext.WriteLine(this.ToXmlDcs(bag)); } public string ToXmlDcs(object value, bool throwExceptions = false) { var ser = new DataContractSerializer(value.GetType(), null, int.MaxValue, true, false, null); MemoryStream ms = new MemoryStream(); ser.WriteObject(ms, value); return Encoding.UTF8.GetString(ms.ToArray(), 0, (int)ms.Length); } This DOES work but produces some pretty heinous XML (formatted with line breaks and indentation here): <ArrayOfKeyValueOfstringanyType xmlns="http://schemas.microsoft.com/2003/10/Serialization/Arrays" xmlns:i="http://www.w3.org/2001/XMLSchema-instance"> <KeyValueOfstringanyType> <Key>key</Key> <Value i:type="a:string" xmlns:a="http://www.w3.org/2001/XMLSchema">Value</Value> </KeyValueOfstringanyType> <KeyValueOfstringanyType> <Key>Key2</Key> <Value i:type="a:decimal" xmlns:a="http://www.w3.org/2001/XMLSchema">100.10</Value> </KeyValueOfstringanyType> <KeyValueOfstringanyType> <Key>Key3</Key> <Value i:type="a:guid" xmlns:a="http://schemas.microsoft.com/2003/10/Serialization/">2cd46d2a-a636-4af4-979b-e834d39b6d37</Value> </KeyValueOfstringanyType> <KeyValueOfstringanyType> <Key>Key4</Key> <Value i:type="a:dateTime" xmlns:a="http://www.w3.org/2001/XMLSchema">2011-09-19T17:17:05.4406999-07:00</Value> </KeyValueOfstringanyType> <KeyValueOfstringanyType> <Key>Key5</Key> <Value i:type="a:boolean" xmlns:a="http://www.w3.org/2001/XMLSchema">true</Value> </KeyValueOfstringanyType> <KeyValueOfstringanyType> <Key>Key7</Key> <Value i:type="a:base64Binary" xmlns:a="http://www.w3.org/2001/XMLSchema">Ki1C</Value> </KeyValueOfstringanyType> </ArrayOfKeyValueOfstringanyType> Ouch! That seriously hurts the eye! :-) Worse though it's extremely verbose with all those repetitive namespace declarations. It's good to know that it works in a pinch, but for a human readable/editable solution or something lightweight to store in a database it's not quite ideal. Why should I care? As a little background, in one of my applications I have a need for a flexible property bag that is used on a free form database field on an otherwise static entity. Basically what I have is a standard database record to which arbitrary properties can be added in an XML based string field. I intend to expose those arbitrary properties as a collection from field data stored in XML. The concept is pretty simple: When loading write the data to the collection, when the data is saved serialize the data into an XML string and store it into the database. When reading the data pick up the XML and if the collection on the entity is accessed automatically deserialize the XML into the Dictionary. (I'll talk more about this in another post). While the DataContext Serializer would work, it's verbosity is problematic both for size of the generated XML strings and the fact that users can manually edit this XML based property data in an advanced mode. A clean(er) layout certainly would be preferable and more user friendly. Custom XMLSerialization with a PropertyBag Class So… after a bunch of experimentation with different serialization formats I decided to create a custom PropertyBag class that provides for a serializable Dictionary. It's basically a custom Dictionary<TType,TValue> implementation with the keys always set as string keys. The result are PropertyBag<TValue> and PropertyBag (which defaults to the object type for values). The PropertyBag<TType> and PropertyBag classes provide these features: Subclassed from Dictionary<T,V> Implements IXmlSerializable with a cleanish XML format ToXml() and FromXml() methods to export and import to and from XML strings Static CreateFromXml() method to create an instance It's simple enough as it's merely a Dictionary<string,object> subclass but that supports serialization to a - what I think at least - cleaner XML format. The class is super simple to use: [TestMethod] public void PropertyBagTwoWayObjectSerializationTest() { var bag = new PropertyBag(); bag.Add("key", "Value"); bag.Add("Key2", 100.10M); bag.Add("Key3", Guid.NewGuid()); bag.Add("Key4", DateTime.Now); bag.Add("Key5", true); bag.Add("Key7", new byte[3] { 42,45,66 } ); bag.Add("Key8", null); bag.Add("Key9", new ComplexObject() { Name = "Rick", Entered = DateTime.Now, Count = 10 }); string xml = bag.ToXml(); TestContext.WriteLine(bag.ToXml()); bag.Clear(); bag.FromXml(xml); Assert.IsTrue(bag["key"] as string == "Value"); Assert.IsInstanceOfType( bag["Key3"], typeof(Guid)); Assert.IsNull(bag["Key8"]); //Assert.IsNull(bag["Key10"]); Assert.IsInstanceOfType(bag["Key9"], typeof(ComplexObject)); } This uses the PropertyBag class which uses a PropertyBag<string,object> - which means it returns untyped values of type object. I suspect for me this will be the most common scenario as I'd want to store arbitrary values in the PropertyBag rather than one specific type. The same code with a strongly typed PropertyBag<decimal> looks like this: [TestMethod] public void PropertyBagTwoWayValueTypeSerializationTest() { var bag = new PropertyBag<decimal>(); bag.Add("key", 10M); bag.Add("Key1", 100.10M); bag.Add("Key2", 200.10M); bag.Add("Key3", 300.10M); string xml = bag.ToXml(); TestContext.WriteLine(bag.ToXml()); bag.Clear(); bag.FromXml(xml); Assert.IsTrue(bag.Get("Key1") == 100.10M); Assert.IsTrue(bag.Get("Key3") == 300.10M); } and produces typed results of type decimal. The types can be either value or reference types the combination of which actually proved to be a little more tricky than anticipated due to null and specific string value checks required - getting the generic typing right required use of default(T) and Convert.ChangeType() to trick the compiler into playing nice. Of course the whole raison d'etre for this class is the XML serialization. You can see in the code above that we're doing a .ToXml() and .FromXml() to serialize to and from string. The XML produced for the first example looks like this: <?xml version="1.0" encoding="utf-8"?> <properties> <item> <key>key</key> <value>Value</value> </item> <item> <key>Key2</key> <value type="decimal">100.10</value> </item> <item> <key>Key3</key> <value type="___System.Guid"> <guid>f7a92032-0c6d-4e9d-9950-b15ff7cd207d</guid> </value> </item> <item> <key>Key4</key> <value type="datetime">2011-09-26T17:45:58.5789578-10:00</value> </item> <item> <key>Key5</key> <value type="boolean">true</value> </item> <item> <key>Key7</key> <value type="base64Binary">Ki1C</value> </item> <item> <key>Key8</key> <value type="nil" /> </item> <item> <key>Key9</key> <value type="___Westwind.Tools.Tests.PropertyBagTest+ComplexObject"> <ComplexObject> <Name>Rick</Name> <Entered>2011-09-26T17:45:58.5789578-10:00</Entered> <Count>10</Count> </ComplexObject> </value> </item> </properties>   The format is a bit cleaner than the DataContractSerializer. Each item is serialized into <key> <value> pairs. If the value is a string no type information is written. Since string tends to be the most common type this saves space and serialization processing. All other types are attributed. Simple types are mapped to XML types so things like decimal, datetime, boolean and base64Binary are encoded using their Xml type values. All other types are embedded with a hokey format that describes the .NET type preceded by a three underscores and then are encoded using the XmlSerializer. You can see this best above in the ComplexObject encoding. For custom types this isn't pretty either, but it's more concise than the DCS and it works as long as you're serializing back and forth between .NET clients at least. The XML generated from the second example that uses PropertyBag<decimal> looks like this: <?xml version="1.0" encoding="utf-8"?> <properties> <item> <key>key</key> <value type="decimal">10</value> </item> <item> <key>Key1</key> <value type="decimal">100.10</value> </item> <item> <key>Key2</key> <value type="decimal">200.10</value> </item> <item> <key>Key3</key> <value type="decimal">300.10</value> </item> </properties>   How does it work As I mentioned there's nothing fancy about this solution - it's little more than a subclass of Dictionary<T,V> that implements custom Xml Serialization and a couple of helper methods that facilitate getting the XML in and out of the class more easily. But it's proven very handy for a number of projects for me where dynamic data storage is required. Here's the code: /// <summary> /// Creates a serializable string/object dictionary that is XML serializable /// Encodes keys as element names and values as simple values with a type /// attribute that contains an XML type name. Complex names encode the type /// name with type='___namespace.classname' format followed by a standard xml /// serialized format. The latter serialization can be slow so it's not recommended /// to pass complex types if performance is critical. /// </summary> [XmlRoot("properties")] public class PropertyBag : PropertyBag<object> { /// <summary> /// Creates an instance of a propertybag from an Xml string /// </summary> /// <param name="xml">Serialize</param> /// <returns></returns> public static PropertyBag CreateFromXml(string xml) { var bag = new PropertyBag(); bag.FromXml(xml); return bag; } } /// <summary> /// Creates a serializable string for generic types that is XML serializable. /// /// Encodes keys as element names and values as simple values with a type /// attribute that contains an XML type name. Complex names encode the type /// name with type='___namespace.classname' format followed by a standard xml /// serialized format. The latter serialization can be slow so it's not recommended /// to pass complex types if performance is critical. /// </summary> /// <typeparam name="TValue">Must be a reference type. For value types use type object</typeparam> [XmlRoot("properties")] public class PropertyBag<TValue> : Dictionary<string, TValue>, IXmlSerializable { /// <summary> /// Not implemented - this means no schema information is passed /// so this won't work with ASMX/WCF services. /// </summary> /// <returns></returns> public System.Xml.Schema.XmlSchema GetSchema() { return null; } /// <summary> /// Serializes the dictionary to XML. Keys are /// serialized to element names and values as /// element values. An xml type attribute is embedded /// for each serialized element - a .NET type /// element is embedded for each complex type and /// prefixed with three underscores. /// </summary> /// <param name="writer"></param> public void WriteXml(System.Xml.XmlWriter writer) { foreach (string key in this.Keys) { TValue value = this[key]; Type type = null; if (value != null) type = value.GetType(); writer.WriteStartElement("item"); writer.WriteStartElement("key"); writer.WriteString(key as string); writer.WriteEndElement(); writer.WriteStartElement("value"); string xmlType = XmlUtils.MapTypeToXmlType(type); bool isCustom = false; // Type information attribute if not string if (value == null) { writer.WriteAttributeString("type", "nil"); } else if (!string.IsNullOrEmpty(xmlType)) { if (xmlType != "string") { writer.WriteStartAttribute("type"); writer.WriteString(xmlType); writer.WriteEndAttribute(); } } else { isCustom = true; xmlType = "___" + value.GetType().FullName; writer.WriteStartAttribute("type"); writer.WriteString(xmlType); writer.WriteEndAttribute(); } // Actual deserialization if (!isCustom) { if (value != null) writer.WriteValue(value); } else { XmlSerializer ser = new XmlSerializer(value.GetType()); ser.Serialize(writer, value); } writer.WriteEndElement(); // value writer.WriteEndElement(); // item } } /// <summary> /// Reads the custom serialized format /// </summary> /// <param name="reader"></param> public void ReadXml(System.Xml.XmlReader reader) { this.Clear(); while (reader.Read()) { if (reader.NodeType == XmlNodeType.Element && reader.Name == "key") { string xmlType = null; string name = reader.ReadElementContentAsString(); // item element reader.ReadToNextSibling("value"); if (reader.MoveToNextAttribute()) xmlType = reader.Value; reader.MoveToContent(); TValue value; if (xmlType == "nil") value = default(TValue); // null else if (string.IsNullOrEmpty(xmlType)) { // value is a string or object and we can assign TValue to value string strval = reader.ReadElementContentAsString(); value = (TValue) Convert.ChangeType(strval, typeof(TValue)); } else if (xmlType.StartsWith("___")) { while (reader.Read() && reader.NodeType != XmlNodeType.Element) { } Type type = ReflectionUtils.GetTypeFromName(xmlType.Substring(3)); //value = reader.ReadElementContentAs(type,null); XmlSerializer ser = new XmlSerializer(type); value = (TValue)ser.Deserialize(reader); } else value = (TValue)reader.ReadElementContentAs(XmlUtils.MapXmlTypeToType(xmlType), null); this.Add(name, value); } } } /// <summary> /// Serializes this dictionary to an XML string /// </summary> /// <returns>XML String or Null if it fails</returns> public string ToXml() { string xml = null; SerializationUtils.SerializeObject(this, out xml); return xml; } /// <summary> /// Deserializes from an XML string /// </summary> /// <param name="xml"></param> /// <returns>true or false</returns> public bool FromXml(string xml) { this.Clear(); // if xml string is empty we return an empty dictionary if (string.IsNullOrEmpty(xml)) return true; var result = SerializationUtils.DeSerializeObject(xml, this.GetType()) as PropertyBag<TValue>; if (result != null) { foreach (var item in result) { this.Add(item.Key, item.Value); } } else // null is a failure return false; return true; } /// <summary> /// Creates an instance of a propertybag from an Xml string /// </summary> /// <param name="xml"></param> /// <returns></returns> public static PropertyBag<TValue> CreateFromXml(string xml) { var bag = new PropertyBag<TValue>(); bag.FromXml(xml); return bag; } } } The code uses a couple of small helper classes SerializationUtils and XmlUtils for mapping Xml types to and from .NET, both of which are from the WestWind,Utilities project (which is the same project where PropertyBag lives) from the West Wind Web Toolkit. The code implements ReadXml and WriteXml for the IXmlSerializable implementation using old school XmlReaders and XmlWriters (because it's pretty simple stuff - no need for XLinq here). Then there are two helper methods .ToXml() and .FromXml() that basically allow your code to easily convert between XML and a PropertyBag object. In my code that's what I use to actually to persist to and from the entity XML property during .Load() and .Save() operations. It's sweet to be able to have a string key dictionary and then be able to turn around with 1 line of code to persist the whole thing to XML and back. Hopefully some of you will find this class as useful as I've found it. It's a simple solution to a common requirement in my applications and I've used the hell out of it in the  short time since I created it. Resources You can find the complete code for the two classes plus the helpers in the Subversion repository for Westwind.Utilities. You can grab the source files from there or download the whole project. You can also grab the full Westwind.Utilities assembly from NuGet and add it to your project if that's easier for you. PropertyBag Source Code SerializationUtils and XmlUtils Westwind.Utilities Assembly on NuGet (add from Visual Studio) © Rick Strahl, West Wind Technologies, 2005-2011Posted in .NET  CSharp   Tweet (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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  • 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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  • Component must be a valid peer (when i remove frame.add(Component);)

    - by boyd
    i have this code here for creating and drawing array of pixels into an image import javax.swing.JFrame; import java.awt.Canvas; import java.awt.Graphics; import java.awt.image.BufferStrategy; import java.awt.image.BufferedImage; import java.awt.image.DataBufferInt; public class test extends Canvas implements Runnable{ private static final long serialVersionUID = 1L; public static int WIDTH = 800; public static int HEIGHT = 600; public boolean running=true; public int[] pixels; public BufferedImage img; public static JFrame frame; private Thread thread; public static void main(String[] arg) { test wind = new test(); frame = new JFrame("WINDOW"); frame.add(wind); frame.setVisible(true); frame.setSize(WIDTH, HEIGHT); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); wind.init(); } public void init(){ thread=new Thread(this); thread.start(); img=new BufferedImage(WIDTH, HEIGHT,BufferedImage.TYPE_INT_RGB); pixels=((DataBufferInt)img.getRaster().getDataBuffer()).getData(); } public void run(){ while(running){ render(); try { thread.sleep(55); } catch (InterruptedException e) { e.printStackTrace(); } } } public void render(){ BufferStrategy bs=this.getBufferStrategy(); if(bs==null){ createBufferStrategy(4); return; } drawRect(0,0,150,150); Graphics g= bs.getDrawGraphics(); g.drawImage(img, 0, 0, WIDTH, HEIGHT, null); g.dispose(); bs.show(); } private void drawRect(int x, int y, int w, int h) { for(int i=x;i<w;i++) for(int j=x;j<h;j++) pixels[i+j*WIDTH]=346346; } } Why i get "Component must be a valid peer" error when i remove the line: frame.add(wind); Why I want to remove it? Because I want to create a frame using a class object(from another file) and use the code Window myWindow= new Window() to do exactly the same thing BTW: who knows Java and understands what i wrote please send me a message with your skype or yahoo messenger id.I want to cooperate with you for a project (graphics engine for games)

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  • Removing the XML Formatter from ASP.NET Web API Applications

    - by Rick Strahl
    ASP.NET Web API's default output format is supposed to be JSON, but when I access my Web APIs using the browser address bar I'm always seeing an XML result instead. When working on AJAX application I like to test many of my AJAX APIs with the browser while working on them. While I can't debug all requests this way, GET requests are easy to test in the browser especially if you have JSON viewing options set up in your various browsers. If I preview a Web API request in most browsers I get an XML response like this: Why is that? Web API checks the HTTP Accept headers of a request to determine what type of output it should return by looking for content typed that it has formatters registered for. This automatic negotiation is one of the great features of Web API because it makes it easy and transparent to request different kinds of output from the server. In the case of browsers it turns out that most send Accept headers that look like this (Chrome in this case): Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8 Web API inspects the entire list of headers from left to right (plus the quality/priority flag q=) and tries to find a media type that matches its list of supported media types in the list of formatters registered. In this case it matches application/xml to the Xml formatter and so that's what gets returned and displayed. To verify that Web API indeed defaults to JSON output by default you can open the request in Fiddler and pop it into the Request Composer, remove the application/xml header and see that the output returned comes back in JSON instead. An accept header like this: Accept: text/html,application/xhtml+xml,*/*;q=0.9 or leaving the Accept header out altogether should give you a JSON response. Interestingly enough Internet Explorer 9 also displays JSON because it doesn't include an application/xml Accept header: Accept: text/html, application/xhtml+xml, */* which for once actually seems more sensible. Removing the XML Formatter We can't easily change the browser Accept headers (actually you can by delving into the config but it's a bit of a hassle), so can we change the behavior on the server? When working on AJAX applications I tend to not be interested in XML results and I always want to see JSON results at least during development. Web API uses a collection of formatters and you can go through this list and remove the ones you don't want to use - in this case the XmlMediaTypeFormatter. To do this you can work with the HttpConfiguration object and the static GlobalConfiguration object used to configure it: protected void Application_Start(object sender, EventArgs e) { // Action based routing (used for RPC calls) RouteTable.Routes.MapHttpRoute( name: "StockApi", routeTemplate: "stocks/{action}/{symbol}", defaults: new { symbol = RouteParameter.Optional, controller = "StockApi" } ); // WebApi Configuration to hook up formatters and message handlers RegisterApis(GlobalConfiguration.Configuration); } public static void RegisterApis(HttpConfiguration config) { // remove default Xml handler var matches = config.Formatters .Where(f = f.SupportedMediaTypes .Where(m = m.MediaType.ToString() == "application/xml" || m.MediaType.ToString() == "text/xml") .Count() 0) .ToList() ; foreach (var match in matches) config.Formatters.Remove(match); } } That LINQ code is quite a mouthful of nested collections, but it does the trick to remove the formatter based on the content type. You can also look for the specific formatter (XmlMediatTypeFormatter) by its type name which is simpler, but it's better to search for the supported types as this will work even if there are other custom formatters added. Once removed, now the browser request results in a JSON response: It's a simple solution to a small debugging task that's made my life easier. Maybe you find it useful too…© Rick Strahl, West Wind Technologies, 2005-2012Posted in Web Api  ASP.NET   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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  • DevConnections Slides and Samples Posted

    - by Rick Strahl
    I’ve posted the slides and samples to my DevConnections Sessions for anyone interested. I had a lot of fun with my sessions this time around mainly because the sessions picked were a little off the beaten track (well, the handlers/modules and e-commerce sessions anyway). For those of you that attended I hope you found the sessions useful. For the rest of you – you can check out the slides and samples if you like. Here’s what was covered: Introduction to jQuery with ASP.NET This session covered mostly the client side of jQuery demonstrated on a small sample page with a variety of incrementally built up examples of selection and page manipulation. This session also introduces some of the basics of AJAX communication talking to ASP.NET. When I do this session it never turns out exactly the same way and this time around the examples were on the more basic side and purely done with hands on demonstrations rather than walk throughs of more complex examples. Alas this session always feels like it needs another half an hour to get through the full sortiment of functionality. The slides and samples cover a wider variety of topics and there are many examples that demonstrate more advanced operations like interacting with WCF REST services, using client templating and building rich client only windowed interfaces. Download Low Level ASP.NET: Handlers and Modules This session was a look at the ASP.NET pipeline and it discusses some of the ASP.NET base architecture and key components from HttpRuntime on up through the various modules and handlers that make up the ASP.NET/IIS pipeline. This session is fun as there are a number of cool examples that demonstrate the power and flexibility of ASP.NET, but some of the examples were external and interfacing with other technologies so they’re not actually included in the downloadable samples. However, there are still a few cool ones in there – there’s an image resizing handler, an image overlay module that stamps images with Sample if loaded from a certain folder, an OpenID authentication module (which failed during the demo due to the crappy internet connection at DevConnections this year :-}), Response filtering using a generic filter stream component, a generic error handler and a few others. The slides cover a lot of the ASP.NET pipeline flow and various HttpRuntime components. Download Electronic Payment Processing in ASP.NET Applications This session covered the business end and integration of electronic credit card processing and PayPal. A good part of this session deals with what’s involved in payment processing, getting signed up and who you have to deal with for your merchant account. We then took a look at integration of credit card processing via some generic components provided with the session that allow processing using a unified class interface with specific implementations for several of the most common gateway providers including Authorize.NET, PayFlowPro, LinkPoint, BluePay etc. We also briefly looked at PayPal Classic implementation which provides a quick and cheap if not quite as professional mechanism for taking payments online. The samples provide the Credit Card processing wrappers for the various gateway providers as well as a PayPal helper class to generate the PayPal redirect urls as well as helper code for dealing with IPN callbacks. Download Hope some of you will find the material useful. Enjoy.© Rick Strahl, West Wind Technologies, 2005-2010Posted in ASP.NET  

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  • Displaying JSON in your Browser

    - by Rick Strahl
    Do you work with AJAX requests a lot and need to quickly check URLs for JSON results? Then you probably know that it’s a fairly big hassle to examine JSON results directly in the browser. Yes, you can use FireBug or Fiddler which work pretty well for actual AJAX requests, but if you just fire off a URL for quick testing in the browser you usually get hit by the Save As dialog and the download manager, followed by having to open the saved document in a text editor in FireFox. Enter JSONView which allows you to simply display JSON results directly in the browser. For example, imagine I have a URL like this: http://localhost/westwindwebtoolkitweb/RestService.ashx?Method=ReturnObject&format=json&Name1=Rick&Name2=John&date=12/30/2010 typed directly into the browser and that that returns a complex JSON object. With JSONView the result looks like this: No fuss, no muss. It just works. Here the result is an array of Person objects that contain additional address child objects displayed right in the browser. JSONView basically adds content type checking for application/json results and when it finds a JSON result takes over the rendering and formats the display in the browser. Note that it re-formats the raw JSON as well for a nicer display view along with collapsible regions for objects. You can still use View Source to see the raw JSON string returned. For me this is a huge time-saver. As I work with AJAX result data using GET and REST style URLs quite a bit it’s a big timesaver. To quickly and easily display JSON is a key feature in my development day and JSONView for all its simplicity fits that bill for me. If you’re doing AJAX development and you often review URL based JSON results do yourself a favor and pick up a copy of JSONView. Other Browsers JSONView works only with FireFox – what about other browsers? Chrome Chrome actually displays raw JSON responses as plain text without any plug-ins. There’s no plug-in or configuration needed, it just works, although you won’t get any fancy formatting. [updated from comments] There’s also a port of JSONView available for Chrome from here: https://chrome.google.com/webstore/detail/chklaanhfefbnpoihckbnefhakgolnmc It looks like it works just about the same as the JSONView plug-in for FireFox. Thanks for all that pointed this out… Internet Explorer Internet Explorer probably has the worst response to JSON encoded content: It displays an error page as it apparently tries to render JSON as XML: Yeah that seems real smart – rendering JSON as an XML document. WTF? To get at the actual JSON output, you can use View Source. To get IE to display JSON directly as text you can add a Mime type mapping in the registry:   Create a new application/json key in: HKEY_CLASSES_ROOT\MIME\Database\ContentType\application/json Add a string value of CLSID with a value of {25336920-03F9-11cf-8FD0-00AA00686F13} Add a DWORD value of Encoding with a value of 80000 I can’t take credit for this tip – found it here first on Sky Sander’s Blog. Note that the CLSID can be used for just about any type of text data you want to display as plain text in the IE. It’s the in-place display mechanism and it should work for most text content. For example it might also be useful for looking at CSS and JS files inside of the browser instead of downloading those documents as well. © Rick Strahl, West Wind Technologies, 2005-2011Posted in ASP.NET  AJAX  

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  • Visual Studio 2010 Beta 2 Startup Failures

    - by Rick Strahl
    I’ve been working with VS 2010 Beta 2 for a while now and while it works Ok most of the time it seems the environment is very, very fragile when it comes to crashes and installed packages. Specifically I’ve been working just fine for days, then when VS 2010 crashes it will not re-start. Instead I get the good old Application cannot start dialog: Other failures I’ve seen bring forth other just as useful dialogs with information overload like Operation cannot be performed which for me specifically happens when trying to compile any project. After a bit of digging around and a post to Microsoft Connect the solution boils down to resetting the VS.NET environment. The Application Cannot Start issue stems from a package load failure of some sort, so the work around for this is typically: c:\program files\Visual Studio 2010\Common7\IDE\devenv.exe /ResetSkipPkgs In most cases that should do the trick. If it doesn’t and the error doesn’t go away the more drastic: c:\program files\Visual Studio 2010\Common7\IDE\devenv.exe /ResetSettings is required which resets all settings in VS to its installation defaults. Between these two I’ve always been able to get VS to startup and run properly. BTW it’s handy to keep a list of command line options for Visual Studio around: http://msdn.microsoft.com/en-us/library/xee0c8y7%28VS.100%29.aspx Note that the /? option in VS 2010 doesn’t display all the options available but rather displays the ‘demo version’ message instead, so the above should be helpful. Also note that unless you install Visual C++ the Visual Studio Command Prompt icon is not automatically installed so you may have to navigate manually to the appropriate folder above. Cannot Build Failures If you get the Cannot compile error dialog, there is another thing that have worked for me: Change your project build target from Debug to Release (or whatever – just change it) and compile again. If that doesn’t work doing the reset steps above will do it for me. It appears this failure comes from some sort of interference of other versions of Visual Studio installed on the system and running another version first. Resetting the build target explicitly seems to reset the build providers to a normalized state so that things work in many cases. But not all. Worst case – resetting settings will do it. The bottom line for working in VS 2010 has been – don’t get too attached to your custom settings as they will get blown away quite a bit. I’ve probably been through 20 or more of these VS resets although I’ve been working with it quite a bit on an internal project. It’s kind of frustrating to see this kind of high level instability in a Beta 2 product which is supposedly the last public beta they will put out. On the other hand this beta has been otherwise rather stable and performance is roughly equivalent to VS 2008. Although I mention the crash above – crashes I’ve seen have been relatively rare and no more frequent than in VS 2008 it seems. Given the drastic UI changes in VS 2010 (using WPF for the shell and editor) I’m actually impressed that the product is as stable as it is at this point. Also I was seriously worried about text quality going to a WPF model, but thankfully WPF 4.0 addresses the blurry text issue with native font rendering to render text on non-cleartype enabled systems crisply. Anyway I hope that these notes are helpful to some of you playing around with the beta and running into problems. Hopefully you won’t need them :-}© Rick Strahl, West Wind Technologies, 2005-2010

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  • Amazon Product Advertising API SOAP Namespace Changes

    - by Rick Strahl
    About two months ago (twowards the end of February 2012 I think) Amazon decided to change the namespace of the Product Advertising API. The error that would come up was: <ItemSearchResponse > was not expected. If you've used the Amazon Product Advertising API you probably know that Amazon has made it a habit to break the services every few years or so and I guess last month was about the time for another one. Basically the service namespace of the document has been changed and responses from the service just failed outright even though the rest of the schema looks fine. Now I looked around for a while trying to find a recent update to the Product Advertising API - something semi-official looking but everything is dated around 2009. Really??? And it's not just .NET - the newest thing on the sample/APIs is dated early 2011 and a handful of 2010 samples. There are newer full APIs for the 'cloud' offerings, but the Product Advertising API apparently isn't part of that. After searching for quite a bit trying to trace this down myself and trying some of the newer samples (which also failed) I found an obscure forum post that describes the solution of getting past the namespace issue. FWIW, I've been using an old version of the Product Advertising API using the old Microsoft WSE3 services (pre-WCF), which provides some of the WS* security features required by the Amazon service. The fix for this code is to explicitly override the namespace declaration on each of the imported service method signatures. The old service namespace (at least on my build) was: http://webservices.amazon.com/AWSECommerceService/2009-03-31 and it should be changed to: http://webservices.amazon.com/AWSECommerceService/2011-08-01 Change it on the class header:[Microsoft.Web.Services3.Messaging.SoapService("http://webservices.amazon.com/AWSECommerceService/2011-08-01")] [System.Xml.Serialization.XmlIncludeAttribute(typeof(Property[]))] [System.Xml.Serialization.XmlIncludeAttribute(typeof(BrowseNode[]))] [System.Xml.Serialization.XmlIncludeAttribute(typeof(TransactionItem[]))] public partial class AWSECommerceService : Microsoft.Web.Services3.Messaging.SoapClient { and on all method signatures:[Microsoft.Web.Services3.Messaging.SoapMethodAttribute("http://soap.amazon.com/ItemSearch")] [return: System.Xml.Serialization.XmlElementAttribute("ItemSearchResponse", Namespace="http://webservices.amazon.com/AWSECommerceService/2011-08-01")] public ItemSearchResponse ItemSearch(ItemSearch ItemSearch1) { Microsoft.Web.Services3.SoapEnvelope results = base.SendRequestResponse("ItemSearch", ItemSearch1); return ((ItemSearchResponse)(results.GetBodyObject(typeof(ItemSearchResponse), this.SoapServiceAttribute.TargetNamespace))); } It's easy to do with a Search and Replace on the above strings. Amazon Services <rant> FWIW, I've not been impressed by Amazon's service offerings. While the services work well, their documentation and tool support is absolutely horrendous. I was recently working with a customer on an old AWS application and their old API had been completely removed with a new API that wasn't even a close match. One old API call resulted in requiring three different APIs to perform the same functionality. We had to re-write the entire piece from scratch essentially. The documentation was downright wrong, and incomplete and so scattered it was next to impossible to follow. The examples weren't examples at all - they're mockups of real service calls with fake data that didn't even provide everything that was required to make same service calls work. Additionally there appears to be just about no public support from Amazon, only peer support which is sparse at best - and getting a hold of somebody at Amazon, even for pay seems to be mythical task. It's a terrible business model they have going. I can't see why anybody would put themselves through this sort of customer and development experience. Sad really, but an experience we see more and more these days. Nobody puts in the time to document anything anymore, leaving it to devs to figure this stuff out over and over again… </rant>© Rick Strahl, West Wind Technologies, 2005-2012Posted in CSharp  Web Services   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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  • WCF REST Service Activation Errors when AspNetCompatibility is enabled

    - by Rick Strahl
    I’m struggling with an interesting problem with WCF REST since last night and I haven’t been able to track this down. I have a WCF REST Service set up and when accessing the .SVC file it crashes with a version mismatch for System.ServiceModel: Server Error in '/AspNetClient' Application. Could not load type 'System.ServiceModel.Activation.HttpHandler' from assembly 'System.ServiceModel, Version=3.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'.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.TypeLoadException: Could not load type 'System.ServiceModel.Activation.HttpHandler' from assembly 'System.ServiceModel, Version=3.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'.Source Error: An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below. Stack Trace: [TypeLoadException: Could not load type 'System.ServiceModel.Activation.HttpHandler' from assembly 'System.ServiceModel, Version=3.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'.] System.RuntimeTypeHandle.GetTypeByName(String name, Boolean throwOnError, Boolean ignoreCase, Boolean reflectionOnly, StackCrawlMarkHandle stackMark, Boolean loadTypeFromPartialName, ObjectHandleOnStack type) +0 System.RuntimeTypeHandle.GetTypeByName(String name, Boolean throwOnError, Boolean ignoreCase, Boolean reflectionOnly, StackCrawlMark& stackMark, Boolean loadTypeFromPartialName) +95 System.RuntimeType.GetType(String typeName, Boolean throwOnError, Boolean ignoreCase, Boolean reflectionOnly, StackCrawlMark& stackMark) +54 System.Type.GetType(String typeName, Boolean throwOnError, Boolean ignoreCase) +65 System.Web.Compilation.BuildManager.GetType(String typeName, Boolean throwOnError, Boolean ignoreCase) +69 System.Web.Configuration.HandlerFactoryCache.GetTypeWithAssert(String type) +38 System.Web.Configuration.HandlerFactoryCache.GetHandlerType(String type) +13 System.Web.Configuration.HandlerFactoryCache..ctor(String type) +19 System.Web.HttpApplication.GetFactory(String type) +81 System.Web.MaterializeHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +223 System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +184 Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.1 What’s really odd about this is that it crashes only if it runs inside of IIS (it works fine in Cassini) and only if ASP.NET Compatibility is enabled in web.config:<serviceHostingEnvironment aspNetCompatibilityEnabled="true" multipleSiteBindingsEnabled="true" /> Arrrgh!!!!! After some experimenting and some help from Glenn Block and his team mates I was able to track down the problem in ApplicationHost.config. Specifically the problem was that there were multiple *.svc mappings in the ApplicationHost.Config file and the older 2.0 runtime specific versions weren’t marked for the proper runtime. Because these handlers show up at the top of the list they execute first resulting in assembly load errors for the wrong version assembly. To fix this problem I ended up making a couple changes in applicationhost.config. On the machine level root’s Handler mappings I had an entry that looked like this:<add name="svc-Integrated" path="*.svc" verb="*" type="System.ServiceModel.Activation.HttpHandler, System.ServiceModel, Version=3.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" preCondition="integratedMode" /> and it needs to be changed to this:<add name="svc-Integrated" path="*.svc" verb="*" type="System.ServiceModel.Activation.HttpHandler, System.ServiceModel, Version=3.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" preCondition="integratedMode,runtimeVersionv2.0" />Notice the explicit runtime version assignment in the preCondition attribute which is key to keep ASP.NET 4.0 from executing that handler. The key here is that the runtime version needs to be set explicitly so that the various *.svc handlers don’t fire only in the order defined which in case of a .NET 4.0 app with the original setting would result in an incompatible version of System.ComponentModel to load.What was really hard to track this down is that even when looking in the debugger when launching the Web app, the AppDomain assembly loads showed System.ServiceModel V4.0 starting up just fine. Apparently the ASP.NET runtime load occurs at a different point and that’s when things break.So how did this break? According to the Microsoft folks it’s some older tools that got installed that change the default service handlers. There’s a blog entry that points at this problem with more detail:http://blogs.iis.net/webtopics/archive/2010/04/28/system-typeloadexception-for-system-servicemodel-activation-httpmodule-in-asp-net-4.aspxNote that I tried running aspnet_regiis and that did not fix the problem for me. I had to manually change the entries in applicationhost.config.   © Rick Strahl, West Wind Technologies, 2005-2011Posted in AJAX   ASP.NET  WCF  

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  • Restricting Input in HTML Textboxes to Numeric Values

    - by Rick Strahl
    Ok, here’s a fairly basic one – how to force a textbox to accept only numeric input. Somebody asked me this today on a support call so I did a few quick lookups online and found the solutions listed rather unsatisfying. The main problem with most of the examples I could dig up was that they only include numeric values, but that provides a rather lame user experience. You need to still allow basic operational keys for a textbox – navigation keys, backspace and delete, tab/shift tab and the Enter key - to work or else the textbox will feel very different than a standard text box. Yes there are plug-ins that allow masked input easily enough but most are fixed width which is difficult to do with plain number input. So I took a few minutes to write a small reusable plug-in that handles this scenario. Imagine you have a couple of textboxes on a form like this: <div class="containercontent"> <div class="label">Enter a number:</div> <input type="text" name="txtNumber1" id="txtNumber1" value="" class="numberinput" /> <div class="label">Enter a number:</div> <input type="text" name="txtNumber2" id="txtNumber2" value="" class="numberinput" /> </div> and you want to restrict input to numbers. Here’s a small .forceNumeric() jQuery plug-in that does what I like to see in this case: [Updated thanks to Elijah Manor for a couple of small tweaks for additional keys to check for] <script type="text/javascript"> $(document).ready(function () { $(".numberinput").forceNumeric(); }); // forceNumeric() plug-in implementation jQuery.fn.forceNumeric = function () { return this.each(function () { $(this).keydown(function (e) { var key = e.which || e.keyCode; if (!e.shiftKey && !e.altKey && !e.ctrlKey && // numbers key >= 48 && key <= 57 || // Numeric keypad key >= 96 && key <= 105 || // comma, period and minus key == 190 || key == 188 || key == 109 || // Backspace and Tab and Enter key == 8 || key == 9 || key == 13 || // Home and End key == 35 || key == 36 || // left and right arrows key == 37 || key == 39 || // Del and Ins key == 46 || key == 45) return true; return false; }); }); } </script> With the plug-in in place in your page or an external .js file you can now simply use a selector to apply it: $(".numberinput").forceNumeric(); The plug-in basically goes through each selected element and hooks up a keydown() event handler. When a key is pressed the handler is fired and the keyCode of the event object is sent. Recall that jQuery normalizes the JavaScript Event object between browsers. The code basically white-lists a few key codes and rejects all others. It returns true to indicate the keypress is to go through or false to eat the keystroke and not process it which effectively removes it. Simple and low tech, and it works without too much change of typical text box behavior.© Rick Strahl, West Wind Technologies, 2005-2011Posted in JavaScript  jQuery  HTML  

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  • Opening the Internet Settings Dialog and using Windows Default Network Settings via Code

    - by Rick Strahl
    Ran into a question from a client the other day that asked how to deal with Internet Connection settings for running  HTTP requests. In this case this is an old FoxPro app and it's using WinInet to handle the actual HTTP connection. Another client asked a similar question about using the IE Web Browser control and configuring connection properties. Regardless of platform or tools used to do HTTP connections, you can probably configure custom connection and proxy settings in your application to configure http connection settings manually. However, this is a repetitive process for each application requires you to track system information in your application which is undesirable. Often it's much easier to rely on the system wide proxy settings that Windows provides via the Internet Settings dialog. The dialog is a Control Panel applet (inetcpl.cpl) and is the same dialog that you see when you pop up Internet Explorer's Options dialog: This dialog controls the Windows connection properties that determine how the Windows HTTP stack connects to the Internet and how Proxy's are used if configured. Depending on how the HTTP client is configured - it can typically inherit and use these global settings. Loading the Settings Dialog Programmatically The settings dialog is a Control Panel applet with the name of: inetcpl.cpl and you can use any Shell execution mechanism (Run dialog, ShellExecute API, Process.Start() in .NET etc.) to invoke the dialog. Changes made there are immediately reflected in any applications that use the default connection settings. In .NET you can simply do this to bring up the Internet Settings dialog with the Connection tab enabled: Process.Start("inetcpl.cpl",",4"); In FoxPro you can simply use the RUN command to execute inetcpl.cpl: lcCmd = "inetcpl.cpl ,4" RUN &lcCmd Using the Default Connection/Proxy Settings When using WinInet you specify the Http connect type in the call to InternetOpen() like this (FoxPro code here): hInetConnection=; InternetOpen(THIS.cUserAgent,0,; THIS.chttpproxyname,THIS.chttpproxybypass,0) The second parameter of 0 specifies that the default system proxy settings should be used and it uses the settings from the Internet Settings Connections tab. Other connection options for HTTP connections include 1 - direct (no proxies and ignore system settings), 3 - explicit Proxy specification. In most situations a connection mode setting of 0 should work. In .NET HTTP connections by default are direct connections and so you need to explicitly specify a default proxy or proxy configuration to use. The easiest way to do this is on the application level in the config file: <configuration> <system.net> <defaultProxy> <proxy bypassonlocal="False" autoDetect="True" usesystemdefault="True" /> </defaultProxy> </system.net> </configuration> You can do the same sort of thing in code specifying the proxy explicitly and using System.Net.WebProxy.GetDefaultProxy(). So when making HTTP calls to Web Services or using the HttpWebRequest class you can set the proxy with: StoreService.Proxy = WebProxy.GetDefaultProxy(); All of this is pretty easy to deal with and in my opinion is a way better choice to managing connection settings than having to track this stuff in your own application. Plus if you use default settings, most of the time it's highly likely that the connection settings are already properly configured making further configuration rare.© Rick Strahl, West Wind Technologies, 2005-2011Posted in Windows  HTTP  .NET  FoxPro   Tweet (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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  • ASP.NET Routing not working on IIS 7.0

    - by Rick Strahl
    I ran into a nasty little problem today when deploying an application using ASP.NET 4.0 Routing to my live server. The application and its Routing were working just fine on my dev machine (Windows 7 and IIS 7.5), but when I deployed (Windows 2008 R1 and IIS 7.0) Routing would just not work. Every time I hit a routed url IIS would just throw up a 404 error: This is an IIS error, not an ASP.NET error so this doesn’t actually come from ASP.NET’s routing engine but from IIS’s handling of expressionless URLs. Note that it’s clearly falling through all the way to the StaticFile handler which is the last handler to fire in the typical IIS handler list. In other words IIS is trying to parse the extension less URL and not firing it into ASP.NET but failing. As I mentioned on my local machine this all worked fine and to make sure local and live setups match I re-copied my Web.config, double checked handler mappings in IIS and re-copied the actual application assemblies to the server. It all looked exactly matched. However no workey on the server with IIS 7.0!!! Finally, totally by chance, I remembered the runAllManagedModulesForAllRequests attribute flag on the modules key in web.config and set it to true: <system.webServer> <modules runAllManagedModulesForAllRequests="true"> <add name="ScriptCompressionModule" type="Westwind.Web.ScriptCompressionModule,Westwind.Web" /> </modules> </system.webServer> And lo and behold, Routing started working on the live server and IIS 7.0! This seems really obvious now of course, but the really tricky thing about this is that on IIS 7.5 this key is not necessary. So on my Windows 7 machine ASP.NET Routing was working just fine without the key set. However on IIS 7.0 on my live server the same missing setting was not working. On IIS 7.0 this key must be present or Routing will not work. Oddly on IIS 7.5 it appears that you can’t even turn off the behavior – setting runtAllManagedModuleForAllRequests="false" had no effect at all and Routing continued to work just fine even with the flag set to false, which is NOT what I would have expected. Kind of disappointing too that Windows Server 2008 (R1) can’t be upgraded to IIS 7.5. It sure seems like that should have been possible since the OS server core changes in R2 are pretty minor. For the future I really hope Microsoft will allow updating IIS versions without tying them explicitly to the OS. It looks like that with the release of IIS Express Microsoft has taken some steps to untie some of those tight OS links from IIS. Let’s hope that’s the case for the future – it sure is nice to run the same IIS version on dev and live boxes, but upgrading live servers is too big a deal to do just because an updated OS release came out. Moral of the story – never assume that your dev setup will work as is on the live setup. It took me forever to figure this out because I assumed that because my web.config on the local machine was fine and working and I copied all relevant web.config data to the server it can’t be the configuration settings. I was looking everywhere but in the .config file forever before getting desperate and remembering the flag when I accidentally checked the intellisense settings in the modules key. Never assume anything. The other moral is: Try to keep your dev machine and server OS’s in sync whenever possible. Maybe it’s time to upgrade to Windows Server 2008 R2 after all. More info on Extensionless URLs in IIS Want to find out more exactly on how extensionless Urls work on IIS 7? The check out  How ASP.NET MVC Routing Works and its Impact on the Performance of Static Requests which goes into great detail on the complexities of the process. Thanks to Jeff Graves for pointing me at this article – a great linked reference for this topic!© Rick Strahl, West Wind Technologies, 2005-2011Posted in IIS7  Windows  

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  • Odd MVC 4 Beta Razor Designer Issue

    - by Rick Strahl
    This post is a small cry for help along with an explanation of a problem that is hard to describe on twitter or even a connect bug and written in hopes somebody has seen this before and any ideas on what might cause this. Lots of helpful people had comments on Twitter for me, but they all assumed that the code doesn't run, which is not the case - it's a designer issue. A few days ago I started getting some odd problems in my MVC 4 designer for an app I've been working on for the past 2 weeks. Basically the MVC 4 Razor designer keeps popping me errors, about the call signature to various Html Helper methods being incorrect. It also complains about the ViewBag object and not supporting dynamic requesting to load assemblies into the project. Here's what the designer errors look like: You can see the red error underlines under the ViewBag and an Html Helper I plopped in at the top to demonstrate the behavior. Basically any HtmlHelper I'm accessing is showing the same errors. Note that the code *runs just fine* - it's just the designer that is complaining with Errors. What's odd about this is that *I think* this started only a few days ago and nothing consequential that I can think of has happened to the project or overall installations. These errors aren't critical since the code runs but pretty annoying especially if you're building and have .csHtml files open in Visual Studio mixing these fake errors with real compiler errors. What I've checked Looking at the errors it indeed looks like certain references are missing. I can't make sense of the Html Helpers error, but certainly the ViewBag dynamic error looks like System.Core or Microsoft.CSharp assemblies are missing. Rest assured they are there and the code DOES run just fine at runtime. This is a designer issue only. I went ahead and checked the namespaces that MVC has access to in Razor which lives in the Views folder's web.config file: /Views/web.config For good measure I added <system.web.webPages.razor> <host factoryType="System.Web.Mvc.MvcWebRazorHostFactory, System.Web.Mvc, <split for layout> Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" /> <pages pageBaseType="System.Web.Mvc.WebViewPage"> <namespaces> <add namespace="System.Web.Mvc" /> <add namespace="System.Web.Mvc.Ajax" /> <add namespace="System.Web.Mvc.Html" /> <add namespace="System.Web.Routing" /> <add namespace="System.Linq" /> <add namespace="System.Linq.Expressions" /> <add namespace="ClassifiedsBusiness" /> <add namespace="ClassifiedsWeb"/> <add namespace="Westwind.Utilities" /> <add namespace="Westwind.Web" /> <add namespace="Westwind.Web.Mvc" /> </namespaces> </pages> </system.web.webPages.razor> For good measure I added System.Linq and System.Linq.Expression on which some of the Html.xxxxFor() methods rely, but no luck. So, has anybody seen this before? Any ideas on what might be causing these issues only at design time rather, when the final compiled code runs just fine?© Rick Strahl, West Wind Technologies, 2005-2012Posted in Razor  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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  • IIS not starting: The process cannot access the file because it is being used by another process

    - by Rick Strahl
    Ok, apparently a few people knew about this issue, but it is new to me and has caused me nearly an hour to track down today. What happened is that I’ve been working all day doing some final pre-deployment testing of several tools on my local dev machine. In the process I’ve been starting and stopping several IIS 7 Web sites. At some point I was done and just wanted to start my Default Web Site again and found this  little gem of an error message popping up: The process cannot access the file because it is being used by another process. (Exception from HRESULT: 0x80070020) A lot of headless running around ensued after this, trying to figure out why IIS wouldn’t start. Oddly some sites started right up, others didn’t. I killed INetInfo, all worker processes, tried IISReset a million times and even rebooted – all to no avail. What gives? Skype, you evil Bastard! As it turns out the culprit is – drum roll please - Skype!  What, you may ask, does Skype have to do with IIS and Web Requests? It looks like recent versions of Skype have an option to run over Port 80 and 443 to allow running over corporate firewalls. Which is actually a nice feature that lets Skype work just about anywhere. What’s not so cool is that IIS fails to start up when another application is already using the same port that a Web site is mapped to. In the case of my dev site that’d be port 80 and Skype was hogging it. To fix this issue you can stop Skype from using port 80 and 443 which quickly fixes the problem. Or stop Skype. Duh! To permanently fix the problem in Skype find the option on the Options | Connection tab and uncheck the Use port 80/443 option: Oddly I haven’t run into this problem even though my setup hasn’t changed in quite some time. It appears that it’s bad startup timing that causes this problem to occur. Whatever the circumstance was, Skype somehow ended up starting before IIS.  If Skype is started after IIS has started it will automatically opt for other ports and not use port 80 and so there’s no problem. It’s easy to demonstrate this behavior if you’re looking for it: Stop IIS Stop Skype Start Skype and make a test call Start IIS And voila your error is ready for you! This really shouldn’t be a problem except that it would be really nice if IIS could give a more helpful error message when it can fire up a site because a port is blocked. “The process cannot access a file” is really not a very helpful error message in this scenario… I/O port / file ah what the heck it’s all the same to Windows. Right! I’ve run into this situation quite a bit with other, albeit more obvious applications like running Apache on the local machine for testing and then trying to run an IIS application. Same situation,  although it’s been a while – pre IIS 7 and I think previous versions of IIS actually gave more useful error messages for port blockages and that would be helpful. On the way to figuring this out I ran into some pretty humorous forum posts though with people ragging on why the hell you would be running IIS. Or Skype. The misinformed paranoia police out in full force so to say :-). It’ll be nice to start running IIS Express once Visual Studio 2010 SP1 gets released. Anyway, no surprise that Skype didn’t jump out at me as the culprit right away and I was left fumbling for a while until the Internet came to the rescue. I’m not the first to have found this for sure – I posted a message on Twitter and dozens of people replied they’d run into this before as well. Seems worth mentioning again though – since I’m sure to forget that this happened in a year from now when I hit that same error. Maybe I’ll even find this blog post to remind me…© Rick Strahl, West Wind Technologies, 2005-2011Posted in IIS7  Windows  

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