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  • Session Report: What’s New in JSF: A Complete Tour of JSF 2.2

    - by Janice J. Heiss
    On Wednesday, Ed Burns, Consulting Staff Member at Oracle, presented a session, CON3870 -- “What’s New in JSF: A Complete Tour of JSF 2.2,” in which he provided an update on recent developments in JavaServer Faces 2.2. He began by emphasizing that, “JavaServer Faces 2.2 continues the evolution of the Java EE standard user interface technology. Like previous releases, this iteration is very community-driven and transparent.” He pointed out that since JSF was introduced at the 2001 JavaOne Keynote, it has had a long and successful run and has found a home in applications where the UI logic resides entirely on the server where the model and UI logic is. In such cases, the browser performs fairly simple functions. However, developers can take advantage of the power of browsers, something that Project Avatar is focused on by letting developers author their applications so the UI logic is running on the client and communicating to the back end via RESTful web services. “Most importantly,” remarked Burns, “JSF 2.2 offers a really good migration path because even in the scope of one application you could have an app written with JSF that has its UI logic on the server and, on a gradual basis, you could migrate parts of the app over to use client-side technologies. This can be done at any level of granularity – per page or per collection of pages. It all depends on what you want to do.” His presentation, which focused on the basic new features of JSF 2.2, began by restating the scope of JSF and encouraged attendees to check out Roger Kitain’s session: CON5133 “Techniques for Responsive Real-Time Web UIs.” Burns explained that JSF has endured because, “We still need web apps that are maintainable, localizable, quick to build, accessible, secure, look great and are fun to use.” It is used on every continent – the curious can go here to check out where its unofficial usage is tracked. He emphasized the significance of the UI logic being substantially on the server. This: Separates Component Semantics from Rendering, Allows components to “own” their little patch of the UI -- encode/decode, And offers a well-defined lifecycle: Inversion of Control. Burns reminded attendees that JSR-344, the spec for JSF 2.2, is now on Java Community Process 2.8, a revised version of the JCP that allows for more openness and transparency. He then offered some tools for community access to JSF 2.2:    * Public java.net projects spec http://jsf-spec.java.net/ impl http://jsf.java.net/ Open Source: GPL+Classpath Exception    * Mailing Lists [email protected]                                Public readable archive, JSPA signed member read/write [email protected]                                     Public readable archive, any java.net member read/write                         All mail sent to jsr344-experts is sent to users. * Issue Tracker spec http://jsf-spec.java.net/issues/ impl http://jsf.java.net/issues/ JSF 2.2, which is JSR 344, has a Public Review Draft planned by December 2012 with no need for a Renewal Ballot. The Early Draft Review of JSR 344 was published on December 8, 2011. Interested developers are encouraged to offer their input. Six Big Ticket Features of JSF 2.2 Burns summarized the six big ticket features of JSF 2.2:* HTML5 Friendly Markup Support Pass through attributes and elements * Faces Flows* Cross Site Request Forgery Protection* Loading Facelets via ResourceHandler* File Upload Component* Multi-Templating He explained that he called it “HTML 5 friendly” because there is really nothing HTML 5 specific about it -- it could be 4. But it enables developers to use new elements that are present in HTML5 without having a JSF component library that is written to take advantage of those specifically. It gives the page author the ability to use plain HTML5 to write their page, but to still take advantage of the server-side available in JSF. He presented a demo showing JSF 2.2’s ability to leverage the expressiveness of HTML5. Burns then explained the significance of face flows, which offer function points and quantify how much work has taken place, something of great value to JSF users. He went on to talk about JSF 2.2.’s cross-site request forgery protection (CSRF) and offered details about how it protects applications against attack. Then he talked about JSF 2.2’s File Upload Component and explained that the final specification will have Ajax and non-Ajax support. The current milestone has non-Ajax support implemented. He then went on to explain its capacity to add facelets through ResourceHandler. Previously, JSF 2.0 added Facelets and ResourceHandler as disparate units; now in JSF 2.2 the two concepts are unified. Finally, he explained the concept of multi-templating in JSF 2.2 and went on to discuss more medium-level features of the release. For an easy, low maintenance way of staying in touch with JSF developments go to JSF’s Twitter page where every month or so, important updates are offered.

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  • Postfix mail server: can't connect via POP/IMAP

    - by MelkerOVan
    I've followed this guide on setting up a mail server on my dedicated server. I've been able to send mails from the php application I'm using and the linux commandline (using telnet, php, etc). The problem is that I cannot connect to the server via IMAP/POP which I've setup using Courier. I've tried using thunderbird but it complains that the username or password is wrong. I doubt it is the username/password but I don't know how to trouble shoot this. Edit: Here's the messages in mail.log: Jan 9 22:43:38 mail authdaemond: received auth request, service=imap, authtype=login Jan 9 22:43:38 mail authdaemond: authmysql: trying this module Jan 9 22:43:38 mail authdaemond: SQL query: SELECT id, crypt, "", uid, gid, home, "", "", name, "" FROM users WHERE id = '[email protected]' AND (enabled=1) Jan 9 22:43:38 mail authdaemond: password matches successfully Jan 9 22:43:38 mail authdaemond: authmysql: sysusername=<null>, sysuserid=5000, sysgroupid=5000, homedir=/var/spool/mail/virtual, [email protected], fullname=peter, maildir=<null>, quota=<null>, options=<null> Jan 9 22:43:38 mail authdaemond: authmysql: clearpasswd=<null>, passwd=6SrBcYq65l8QU Jan 9 22:43:38 mail authdaemond: Authenticated: sysusername=<null>, sysuserid=5000, sysgroupid=5000, homedir=/var/spool/mail/virtual, [email protected], fullname=peter, maildir=<null>, quota=<null>, options=<null> Jan 9 22:43:38 mail authdaemond: Authenticated: clearpasswd=peter, passwd=6SrBcYq65l8QU Jan 9 22:43:38 mail imapd: chdir Maildir: No such file or directory

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  • Mail server: can't connect via POP/IMAP

    - by MelkerOVan
    I've followed this guide on setting up a mail server on my dedicated server. I've been able to send mails from the php application I'm using and the linux commandline (using telnet, php, etc). The problem is that I cannot connect to the server via IMAP/POP which I've setup using Courier. I've tried using thunderbird but it complains that the username or password is wrong. I doubt it is the username/password but I don't know how to trouble shoot this. Edit: Here's the messages in mail.log: Jan 9 22:43:38 mail authdaemond: received auth request, service=imap, authtype=login Jan 9 22:43:38 mail authdaemond: authmysql: trying this module Jan 9 22:43:38 mail authdaemond: SQL query: SELECT id, crypt, "", uid, gid, home, "", "", name, "" FROM users WHERE id = '[email protected]' AND (enabled=1) Jan 9 22:43:38 mail authdaemond: password matches successfully Jan 9 22:43:38 mail authdaemond: authmysql: sysusername=<null>, sysuserid=5000, sysgroupid=5000, homedir=/var/spool/mail/virtual, [email protected], fullname=peter, maildir=<null>, quota=<null>, options=<null> Jan 9 22:43:38 mail authdaemond: authmysql: clearpasswd=<null>, passwd=password Jan 9 22:43:38 mail authdaemond: Authenticated: sysusername=<null>, sysuserid=5000, sysgroupid=5000, homedir=/var/spool/mail/virtual, [email protected], fullname=peter, maildir=<null>, quota=<null>, options=<null> Jan 9 22:43:38 mail authdaemond: Authenticated: clearpasswd=peter, passwd=password Jan 9 22:43:38 mail imapd: chdir Maildir: No such file or directory

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  • Is this simple XOR encrypted communication absolutely secure?

    - by user3123061
    Say Alice have 4GB USB flash memory and Peter also have 4GB USB flash memory. They once meet and save on both of memories two files named alice_to_peter.key (2GB) and peter_to_alice.key (2GB) which is randomly generated bits. Then they never meet again and communicate electronicaly. Alice also maintains variable called alice_pointer and Peter maintains variable called peter_pointer which is both initially set to zero. Then when Alice needs to send message to Peter they do: encrypted_message_to_peter[n] = message_to_peter[n] XOR alice_to_peter.key[alice_pointer + n] Where n i n-th byte of message. Then alice_pointer is attached at begining of the encrypted message and (alice_pointer + encrypted message) is sent to Peter and then alice_pointer is incremented by length of message (and for maximum security can be used part of key erased) Peter receives encrypted_message, reads alice_pointer stored at beginning of message and do this: message_to_peter[n] = encrypted_message_to_peter[n] XOR alice_to_peter.key[alice_pointer + n] And for maximum security after reading of message also erases used part of key. - EDIT: In fact this step with this simple algorithm (without integrity check and authentication) decreases security, see Paulo Ebermann post below. When Peter needs to send message to Alice they do analogical steps with peter_to_alice.key and with peter_pointer. With this trivial schema they can send for next 50 years each day 2GB / (50 * 365) = cca 115kB of encrypted data in both directions. If they need more data to send, they simple use larger memory for keys for example with today 2TB harddiscs (1TB keys) is possible to exchange next 50years 60MB/day ! (thats practicaly lots of data for example with using compression its more than hour of high quality voice communication) It Seems to me there is no way for attacker to read encrypted message without keys even if they have infinitely fast computer. because even with infinitely fast computer with brute force they get ever possible message that can fit to length of message, but this is astronomical amount of messages and attacker dont know which of them is actual message. I am right? Is this communication schema really absolutely secure? And if its secure, has this communication method its own name? (I mean XOR encryption is well-known, but whats name of this concrete practical application with use large memories at both communication sides for keys? I am humbly expecting that this application has been invented someone before me :-) ) Note: If its absolutely secure then its amazing because with today low cost large memories it is practicaly much cheeper way of secure communication than expensive quantum cryptography and with equivalent security! EDIT: I think it will be more and more practical in future with lower a lower cost of memories. It can solve secure communication forever. Today you have no certainty if someone succesfuly atack to existing ciphers one year later and make its often expensive implementations unsecure. In many cases before comunication exist step where communicating sides meets personaly, thats time to generate large keys. I think its perfect for military communication for example for communication with submarines which can have installed harddrive with large keys and military central can have harddrive for each submarine they have. It can be also practical in everyday life for example for control your bank account because when you create your account you meet with bank etc.

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  • error in auth.log but can login; LDAP/PAM

    - by Peter
    I have a server running OpenLDAP. When I start a ssh-session I can log in without problems, but an error appears in the logs. This only happens when I log in with a LDAP account (so not with a system account such as root). Any help to eliminate these errors would be much appreciated. The relevant piece from /var/log/auth.log sshd[6235]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=example.com user=peter sshd[6235]: Accepted password for peter from 192.168.1.2 port 2441 ssh2 sshd[6235]: pam_unix(sshd:session): session opened for user peter by (uid=0) pam common-session session [default=1] pam_permit.so session required pam_unix.so session optional pam_ldap.so session required pam_mkhomedir.so skel=/etc/skel umask=0022 session required pam_limits.so session required pam_unix.so session optional pam_ldap.so pam common-auth auth [success=1 default=ignore] pam_ldap.so auth required pam_unix.so nullok_secure use_first_pass auth required pam_permit.so session required pam_mkhomedir.so skel=/etc/skel umask=0022 silent auth sufficient pam_unix.so nullok_secure use_first_pass auth requisite pam_succeed_if.so uid >= 1000 quiet auth sufficient pam_ldap.so use_first_pass auth required pam_deny.so pam common-account account [success=2 new_authtok_reqd=done default=ignore] pam_ldap.so account [success=1 default=ignore] pam_unix.so account required pam_unix.so account sufficient pam_succeed_if.so uid < 1000 quiet account [default=bad success=ok user_unknown=ignore] pam_ldap.so account required pam_permit.so account sufficient pam_ldap.so account sufficient pam_unix.so

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  • Silverlight Cream for June 21, 2011 -- #1110

    - by Dave Campbell
    In this Issue: Colin Eberhardt, Kunal Chowdhury(-2-), Peter Kuhn(-2-, -3-), Mike Gold, WindowsPhoneGeek, Nigel Sampson, Paul Sheriff, Dhananjay Kumar, and Erno de Weerd. Above the Fold: Silverlight: "Silverlight Debug Helper" Peter Kuhn3 WP7: "Metro In Motion #8 – AutoCompleteBox Reveal Animation" Colin Eberhardt Shoutouts: Check out the Top 5 from my friends at SilverlightShow from last week: SilverlightShow for June 13 - 19, 2011 From SilverlightCream.com: Metro In Motion #8 – AutoCompleteBox Reveal Animation Colin Eberhardt found yet another 'Metro In Motion' to duplicate... this one is the auto-complete effect seen in the WP7 email client... check out the video on the post! Windows Phone 7 (Mango) Tutorial - 16 - How to Create a WP7 Alarm Application? Kunal Chowdhury has a couple more of his Mango tutorials up... number 16 (!) is on creating an Alarm app using scheduled tasks. Windows Phone 7 (Mango) Tutorial - 17 - How to Create a WP7 Reminder Application? Kunal Chowdhury's latest is number 17 in the Mango series and he's discussing the Reminder class which is part of the Scheduler namespace. Silverlight Debug Helper Peter Kuhn has deployed a new version of his "Silverlight Debug Helper"... this time he's added support for FireFox and Chrome. Getting ready for the Windows Phone 7 Exam 70-599 (Part 3) Peter Kuhn also has Part 3 of his series posted at SilverlightShow on getting ready for the WP7 exam. XNA for Silverlight developers: Part 13 - Mango (2) Finally, Peter Kuhn's latest XNA for Silverlight developers tutorial is up at SilverlightShow and is the 2nd Mango post for game devs. Detecting Altitude using the WP7 Phone WindowsPhoneGeek apparently turned the reigns of his blog over to Mike Gold for this post about Altitude detection on the WP7. Windows Phone Mango: Getting Started with MVVM in 10 Minutes If you're out there and still haven't gotten your head around MVVM, or want to take another look at why you're beating yourself up doing it [ :) ]... WindowsPhoneGeek has a quick write-up on MVVM and WP7.1 apps Creating app promotional videos Nigel Sampson details how he uses Expression Encoder to produce the app videos he has on his blog for his WP7* apps. Sort Data in Windows Phone using Collection View Source Paul Sheriff's latest post is up, and is another WP7 post. This time on how to sort the data you consume by using a CollectionViewSource object in XAML and not write any code! Viewing Flickr Images on Windows 7.1 Phone or Mango Phone Dhananjay Kumar has a tutorial up for WP7.1 showing how to use the Flickr REST service to display images on your device. Windows Phone 7: Drawing graphics for your application with Inkscape – Part II: Icons Part 2 of Erno de Weerd's Trilogy on Drawing graphics for your WP7* apps in Inkscape is up... this tutorial is all about icons... good stuff! Stay in the 'Light! Twitter SilverlightNews | Twitter WynApse | WynApse.com | Tagged Posts | SilverlightCream Join me @ SilverlightCream | Phoenix Silverlight User Group Technorati Tags: Silverlight    Silverlight 3    Silverlight 4    Windows Phone MIX10

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  • Devoxx UK JCP & Adopt-a-JSR activities

    - by Heather VanCura
    Devoxx UK starts this week!  The JCP Program is organizing many activities throughout the conference, including some tables in the Hackergarten area on 12-13 June.  Topics include Java EE, Data Grids, Java SE 8 (Lambdas and Date & Time API), Money & Currency API and OpenJDK.  We will have two book signings by Richard Warburton and Peter Pilgrim during the Hackergarten - free signed copy of their books at these times - first come, first served (limited quantities available).  Thursday night is the party and the Birds of a Feather (BoF) sessions - come with your favorite questions and topics related to the JCP, Adopt-a-JSR and Adopt OpenJDK Programs!  See below for the schedule of activities; I will fill in details for each session tomorrow.    Thursday 12 June 10:20 - 12:50 Java EE -- Arun Gupta 13:30-17:00 Lambdas/Date & Time API --Richard Warburton & Raoul-Gabriel Urma (also a book signing with Richard Warburon during the afternoon break) 14:30-17:30 Data Grids - Peter Lawrey 14:30-18:00 Money & Currency -- Anatole Tresch 18:45 Adopt OpenJDK BoF session (Java EE BoF runs concurrently) 19:45 JCP & Adopt-a-JSR BoF session Friday 13 June 10:20-13:00 OpenJDK -- Mani Sarkar  10:20- 14:30 Money & Currency -- Anatole Tresch 10:20 - 13:00 Java EE -- Peter Pilgrim 13:00-13:30 Peter Pilgrim Java EE 7 Book signing sponsored by JCP @ lunch time 13:30 - 15:30 JCP.Next/JSR 364 -- Heather VanCura

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  • Get client IP address

    - by Peter Larsson
    Up until now, I have used convuluted approaches to get the current user client IP-address. This weekend I browsed Books Online for SQL Server 2008 R2 (November CTP) and found this new cool function! SELECT  CONNECTIONPROPERTY('net_transport') AS net_transport,         CONNECTIONPROPERTY('protocol_type') AS protocol_type,         CONNECTIONPROPERTY('auth_scheme') AS auth_scheme,         CONNECTIONPROPERTY('local_net_address') AS local_net_address,         CONNECTIONPROPERTY('local_tcp_port') AS local_tcp_port,         CONNECTIONPROPERTY('client_net_address') AS client_net_address  //Peter

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  • GNU Smalltalk package

    - by Peter
    I've installed the GNU Smalltalk package and can get to the SmallTalk command line with the command 'gst'. However, I can't start the visual gst browser using the command: $ gst-browser When I try, this is what I get: peter@peredur:~$ gst-browser Object: CFunctionDescriptor new: 1 "<0x40488720>" error: Invalid C call-out gdk_colormap_get_type SystemExceptions.CInterfaceError(Smalltalk.Exception)>>signal (ExcHandling.st:254) SystemExceptions.CInterfaceError class(Smalltalk.Exception class)>>signal: (ExcHandling.st:161) Smalltalk.CFunctionDescriptor(Smalltalk.CCallable)>>callInto: (CCallable.st:165) GdkColormap class>>getType (GTK.star#VFS.ZipFile/Funcs.st:1) optimized [] in GLib class>>registerAllTypes (GTK.star#VFS.ZipFile/GtkDecl.st:78) Smalltalk.OrderedCollection>>do: (OrderColl.st:68) GLib class>>registerAllTypes (GTK.star#VFS.ZipFile/GtkDecl.st:78) Smalltalk.UndefinedObject>>executeStatements (GTK.star#VFS.ZipFile/GtkImpl.st:1078) Object: CFunctionDescriptor new: 1 "<0x404a7c28>" error: Invalid C call-out gtk_window_new SystemExceptions.CInterfaceError(Exception)>>signal (ExcHandling.st:254) SystemExceptions.CInterfaceError class(Exception class)>>signal: (ExcHandling.st:161) CFunctionDescriptor(CCallable)>>callInto: (CCallable.st:165) GTK.GtkWindow class>>new: (GTK.star#VFS.ZipFile/Funcs.st:1) VisualGST.GtkDebugger(VisualGST.GtkMainWindow)>>initialize (VisualGST.star#VFS.ZipFile/GtkMainWindow.st:131) VisualGST.GtkDebugger class(VisualGST.GtkMainWindow class)>>openSized: (VisualGST.star#VFS.ZipFile/GtkMainWindow.st:19) [] in VisualGST.GtkDebugger class>>open: (VisualGST.star#VFS.ZipFile/Debugger/GtkDebugger.st:16) [] in BlockClosure>>forkDebugger (DebugTools.star#VFS.ZipFile/DebugTools.st:380) [] in Process>>onBlock:at:suspend: (Process.st:392) BlockClosure>>on:do: (BlkClosure.st:193) [] in Process>>onBlock:at:suspend: (Process.st:393) BlockClosure>>ensure: (BlkClosure.st:269) [] in Process>>onBlock:at:suspend: (Process.st:370) [] in BlockClosure>>asContext: (BlkClosure.st:179) BlockContext class>>fromClosure:parent: (BlkContext.st:68) Everything hangs at this point until I hit ^C, after which, I get: Object: CFunctionDescriptor new: 1 "<0x404a7c28>" error: Invalid C call-out gtk_window_new SystemExceptions.CInterfaceError(Exception)>>signal (ExcHandling.st:254) SystemExceptions.CInterfaceError class(Exception class)>>signal: (ExcHandling.st:161) CFunctionDescriptor(CCallable)>>callInto: (CCallable.st:165) GTK.GtkWindow class>>new: (GTK.star#VFS.ZipFile/Funcs.st:1) VisualGST.GtkDebugger(VisualGST.GtkMainWindow)>>initialize (VisualGST.star#VFS.ZipFile/GtkMainWindow.st:131) VisualGST.GtkDebugger class(VisualGST.GtkMainWindow class)>>openSized: (VisualGST.star#VFS.ZipFile/GtkMainWindow.st:19) [] in VisualGST.GtkDebugger class>>open: (VisualGST.star#VFS.ZipFile/Debugger/GtkDebugger.st:16) [] in BlockClosure>>forkDebugger (DebugTools.star#VFS.ZipFile/DebugTools.st:380) [] in Process>>onBlock:at:suspend: (Process.st:392) BlockClosure>>on:do: (BlkClosure.st:193) [] in Process>>onBlock:at:suspend: (Process.st:393) BlockClosure>>ensure: (BlkClosure.st:269) [] in Process>>onBlock:at:suspend: (Process.st:370) [] in BlockClosure>>asContext: (BlkClosure.st:179) BlockContext class>>fromClosure:parent: (BlkContext.st:68) peter@peredur:~$ Is there a problem with this package?

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  • Validating a linked item&rsquo;s data template in Sitecore

    - by Kyle Burns
    I’ve been doing quite a bit of work in Sitecore recently and last week I encountered a situation that it appears many others have hit.  I was working with a field that had been configured originally as a grouped droplink, but now needed to be updated to support additional levels of hierarchy in the folder structure.  If you’ve done any work in Sitecore that statement makes sense, but if not it may seem a bit cryptic.  Sitecore offers a number of different field types and a subset of these field types focus on providing links either to other items on the content tree or to content that is not stored in Sitecore.  In the case of the grouped droplink, the field is configured with a “root” folder and each direct descendant of this folder is considered to be a header for a grouping of other items and displayed in a dropdown.  A picture is worth a thousand words, so consider the following piece of a content tree: If I configure a grouped droplink field to use the “Current” folder as its datasource, the control that gets to my content author looks like this: This presents a nicely organized display and limits the user to selecting only the direct grandchildren of the folder root.  It also presents the limitation that struck as we were thinking through the content architecture and how it would hold up over time – the authors cannot further organize content under the root folder because of the structure required for the dropdown to work.  Over time, not allowing the hierarchy to go any deeper would prevent out authors from being able to organize their content in a way that it would be found when needed, so the grouped droplink data type was not going to fit the bill. I needed to look for an alternative data type that allowed for selection of a single item and limited my choices to descendants of a specific node on the content tree.  After looking at the options available for links in Sitecore and considering them against each other, one option stood out as nearly perfect – the droptree.  This field type stores its data identically to the droplink and allows for the selection of zero or one items under a specific node in the content tree.  By changing my data template to use droptree instead of grouped droplink, the author is now presented with the following when selecting a linked item: Sounds great, but a did say almost perfect – there’s still one flaw.  The code intended to display the linked item is expecting the selection to use a specific data template (or more precisely it makes certain assumptions about the fields that will be present), but the droptree does nothing to prevent the author from selecting a folder (since folders are items too) instead of one of the items contained within a folder.  I looked to see if anyone had already solved this problem.  I found many people discussing the problem, but the closest that I found to a solution was the statement “the best thing would probably be to create a custom validator” with no further discussion in regards to what this validator might look like.  I needed to create my own validator to ensure that the user had not selected a folder.  Since so many people had the same issue, I decided to make the validator as reusable as possible and share it here. The validator that I created inherits from StandardValidator.  In order to make the validator more intuitive to developers that are familiar with the TreeList controls in Sitecore, I chose to implement the following parameters: ExcludeTemplatesForSelection – serves as a “deny list”.  If the data template of the selected item is in this list it will not validate IncludeTemplatesForSelection – this can either be empty to indicate that any template not contained in the exclusion list is acceptable or it can contain the list of acceptable templates Now that I’ve explained the parameters and the purpose of the validator, I’ll let the code do the rest of the talking: 1: /// <summary> 2: /// Validates that a link field value meets template requirements 3: /// specified using the following parameters: 4: /// - ExcludeTemplatesForSelection: If present, the item being 5: /// based on an excluded template will cause validation to fail. 6: /// - IncludeTemplatesForSelection: If present, the item not being 7: /// based on an included template will cause validation to fail 8: /// 9: /// ExcludeTemplatesForSelection trumps IncludeTemplatesForSelection 10: /// if the same value appears in both lists. Lists are comma seperated 11: /// </summary> 12: [Serializable] 13: public class LinkItemTemplateValidator : StandardValidator 14: { 15: public LinkItemTemplateValidator() 16: { 17: } 18:   19: /// <summary> 20: /// Serialization constructor is required by the runtime 21: /// </summary> 22: /// <param name="info"></param> 23: /// <param name="context"></param> 24: public LinkItemTemplateValidator(SerializationInfo info, StreamingContext context) : base(info, context) { } 25:   26: /// <summary> 27: /// Returns whether the linked item meets the template 28: /// constraints specified in the parameters 29: /// </summary> 30: /// <returns> 31: /// The result of the evaluation. 32: /// </returns> 33: protected override ValidatorResult Evaluate() 34: { 35: if (string.IsNullOrWhiteSpace(ControlValidationValue)) 36: { 37: return ValidatorResult.Valid; // let "required" validation handle 38: } 39:   40: var excludeString = Parameters["ExcludeTemplatesForSelection"]; 41: var includeString = Parameters["IncludeTemplatesForSelection"]; 42: if (string.IsNullOrWhiteSpace(excludeString) && string.IsNullOrWhiteSpace(includeString)) 43: { 44: return ValidatorResult.Valid; // "allow anything" if no params 45: } 46:   47: Guid linkedItemGuid; 48: if (!Guid.TryParse(ControlValidationValue, out linkedItemGuid)) 49: { 50: return ValidatorResult.Valid; // probably put validator on wrong field 51: } 52:   53: var item = GetItem(); 54: var linkedItem = item.Database.GetItem(new ID(linkedItemGuid)); 55:   56: if (linkedItem == null) 57: { 58: return ValidatorResult.Valid; // this validator isn't for broken links 59: } 60:   61: var exclusionList = (excludeString ?? string.Empty).Split(','); 62: var inclusionList = (includeString ?? string.Empty).Split(','); 63:   64: if ((inclusionList.Length == 0 || inclusionList.Contains(linkedItem.TemplateName)) 65: && !exclusionList.Contains(linkedItem.TemplateName)) 66: { 67: return ValidatorResult.Valid; 68: } 69:   70: Text = GetText("The field \"{0}\" specifies an item which is based on template \"{1}\". This template is not valid for selection", GetFieldDisplayName(), linkedItem.TemplateName); 71:   72: return GetFailedResult(ValidatorResult.FatalError); 73: } 74:   75: protected override ValidatorResult GetMaxValidatorResult() 76: { 77: return ValidatorResult.FatalError; 78: } 79:   80: public override string Name 81: { 82: get { return @"LinkItemTemplateValidator"; } 83: } 84: }   In this blog entry, I have shared some code that I found useful in solving a problem that seemed fairly common.  Hopefully the next person that is looking for this answer finds it useful as well.

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  • Screen shots and documentation on the cheap

    - by Kyle Burns
    Occasionally I am surprised to open up my toolbox and find a great tool that I've had for years and never noticed.  The other day I had just such an experience with Windows Server 2008.  A co-worker of mine was squinting to read to screenshots that he had taken using the "Print Screen, paste" method in WordPad and asked me if there was a better tool available at a reasonable cost.  My first instinct was to take a look at CamStudio for him, but I also knew that he had an immediate need to take some more screenshots, so I decided to check and see if the Snipping Tool found in Windows 7 is also available in Windows Server 2008.  I clicked the Start button and typed “snip” into the search bar and while the Snipping Tool did not come up, a Control Panel item labeled “Record steps to reproduce a problem” did. The application behind the Control Panel entry was “Problem Steps Recorder” (PSR.exe) and I have confirmed that it is available in Windows 7 and Windows Server 2008 R2 but have not checked other platforms.  It presents a pretty minimal and intuitive interface in providing a “Start Record”, “Stop Record”, and “Add Comment” button.  The “Start Record” button shockingly starts recording and, sure enough, the “Stop Record” button stops recording.  The “Add Comment” button prompts for a comment and for you to highlight the area of the screen to which your comment is related.  Once you’re done recording, the tool outputs an MHT file packaged in a ZIP archive.  This file contains a series of screen shots depicting the user’s interactions and giving timestamps and descriptive text (such as “User left click on “Test” in “My Page – Windows Internet Explorer”) as well as the comments they made along the way and some diagnostics about the applications captured. The Problem Steps Recorder looks like a simple solution to the most common of my needs for documentation that can turn “I can’t understand how to make it do what you’re reporting” to “Oh, I see what you’re talking about and will fix it right away”.  I you’re like me and haven’t yet discovered this tool give it a whirl and see for yourself.

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  • Using Sitecore RenderingContext Parameters as MVC controller action arguments

    - by Kyle Burns
    I have been working with the Technical Preview of Sitecore 6.6 on a project and have been for the most part happy with the way that Sitecore (which truly is an MVC implementation unto itself) has been expanded to support ASP.NET MVC. That said, getting up to speed with the combined platform has not been entirely without stumbles and today I want to share one area where Sitecore could have really made things shine from the "it just works" perspective. A couple days ago I was asked by a colleague about the usage of the "Parameters" field that is defined on Sitecore's Controller Rendering data template. Based on the standard way that Sitecore handles a field named Parameters, I was able to deduce that the field expected key/value pairs separated by the "&" character, but beyond that I wasn't sure and didn't see anything from a documentation perspective to guide me, so it was time to dig and find out where the data in the field was made available. My first thought was that it would be really nice if Sitecore handled the parameters in this field consistently with the way that ASP.NET MVC handles the various parameter collections on the HttpRequest object and automatically maps them to parameters of the action method executing. Being the hopeful sort, I configured a name/value pair on one of my renderings, added a parameter with matching name to the controller action and fired up the bugger to see... that the parameter was not populated. Having established that the field's value was not going to be presented to me the way that I had hoped it would, the next assumption that I would work on was that Sitecore would handle this field similar to how they handle other similar data and would plug it into some ambient object that I could reference from within the controller method. After a considerable amount of guessing, testing, and cracking code open with Redgate's Reflector (a must-have companion to Sitecore documentation), I found that the most direct way to access the parameter was through the ambient RenderingContext object using code similar to: string myArgument = string.Empty; var rc = Sitecore.Mvc.Presentation.RenderingContext.CurrentOrNull; if (rc != null) {     var parms = rc.Rendering.Parameters;     myArgument = parms["myArgument"]; } At this point, we know how this field is used out of the box from Sitecore and can provide information from Sitecore's Content Editor that will be available when the controller action is executing, but it feels a little dirty. In order to properly test the action method I would have to do a lot of setup work and possible use an isolation framework such as Pex and Moles to get at a value that my action method is dependent upon. Notice I said that my method is dependent upon the value but in order to meet that dependency I've accepted another dependency upon Sitecore's RenderingContext.  I'm a big believer in, when possible, ensuring that any piece of code explicitly advertises dependencies using the method signature, so I found myself still wanting this to work the same as if the parameters were in the request route, querystring, or form by being able to add a myArgument parameter to the action method and have this parameter populated by the framework. Lucky for us, the ASP.NET MVC framework is extremely flexible and provides some easy to grok and use extensibility points. ASP.NET MVC is able to provide information from the request as input parameters to controller actions because it uses objects which implement an interface called IValueProvider and have been registered to service the application. The most basic statement of responsibility for an IValueProvider implementation is "I know about some data which is indexed by key. If you hand me the key for a piece of data that I know about I give you that data". When preparing to invoke a controller action, the framework queries registered IValueProvider implementations with the name of each method argument to see if the ValueProvider can supply a value for the parameter. (the rest of this post will assume you're working along and make a lot more sense if you do) Let's pull Sitecore out of the equation for a second to simplify things and create an extremely simple IValueProvider implementation. For this example, I first create a new ASP.NET MVC3 project in Visual Studio, selecting "Internet Application" and otherwise taking defaults (I'm assuming that anyone reading this far in the post either already knows how to do this or will need to take a quick run through one of the many available basic MVC tutorials such as the MVC Music Store). Once the new project is created, go to the Index action of HomeController.  This action sets a Message property on the ViewBag to "Welcome to ASP.NET MVC!" and invokes the View, which has been coded to display the Message. For our example, we will remove the hard coded message from this controller (although we'll leave it just as hard coded somewhere else - this is sample code). For the first step in our exercise, add a string parameter to the Index action method called welcomeMessage and use the value of this argument to set the ViewBag.Message property. The updated Index action should look like: public ActionResult Index(string welcomeMessage) {     ViewBag.Message = welcomeMessage;     return View(); } This represents the entirety of the change that you will make to either the controller or view.  If you run the application now, the home page will display and no message will be presented to the user because no value was supplied to the Action method. Let's now write a ValueProvider to ensure this parameter gets populated. We'll start by creating a new class called StaticValueProvider. When the class is created, we'll update the using statements to ensure that they include the following: using System.Collections.Specialized; using System.Globalization; using System.Web.Mvc; With the appropriate using statements in place, we'll update the StaticValueProvider class to implement the IValueProvider interface. The System.Web.Mvc library already contains a pretty flexible dictionary-like implementation called NameValueCollectionValueProvider, so we'll just wrap that and let it do most of the real work for us. The completed class looks like: public class StaticValueProvider : IValueProvider {     private NameValueCollectionValueProvider _wrappedProvider;     public StaticValueProvider(ControllerContext controllerContext)     {         var parameters = new NameValueCollection();         parameters.Add("welcomeMessage", "Hello from the value provider!");         _wrappedProvider = new NameValueCollectionValueProvider(parameters, CultureInfo.InvariantCulture);     }     public bool ContainsPrefix(string prefix)     {         return _wrappedProvider.ContainsPrefix(prefix);     }     public ValueProviderResult GetValue(string key)     {         return _wrappedProvider.GetValue(key);     } } Notice that the only entry in the collection matches the name of the argument to our HomeController's Index action.  This is the important "secret sauce" that will make things work. We've got our new value provider now, but that's not quite enough to be finished. Mvc obtains IValueProvider instances using factories that are registered when the application starts up. These factories extend the abstract ValueProviderFactory class by initializing and returning the appropriate implementation of IValueProvider from the GetValueProvider method. While I wouldn't do so in production code, for the sake of this example, I'm going to add the following class definition within the StaticValueProvider.cs source file: public class StaticValueProviderFactory : ValueProviderFactory {     public override IValueProvider GetValueProvider(ControllerContext controllerContext)     {         return new StaticValueProvider(controllerContext);     } } Now that we have a factory, we can register it by adding the following line to the end of the Application_Start method in Global.asax.cs: ValueProviderFactories.Factories.Add(new StaticValueProviderFactory()); If you've done everything right to this point, you should be able to run the application and be presented with the home page reading "Hello from the value provider!". Now that you have the basics of the IValueProvider down, you have everything you need to enhance your Sitecore MVC implementation by adding an IValueProvider that exposes values from the ambient RenderingContext's Parameters property. I'll provide the code for the IValueProvider implementation (which should look VERY familiar) and you can use the work we've already done as a reference to create and register the factory: public class RenderingContextValueProvider : IValueProvider {     private NameValueCollectionValueProvider _wrappedProvider = null;     public RenderingContextValueProvider(ControllerContext controllerContext)     {         var collection = new NameValueCollection();         var rc = RenderingContext.CurrentOrNull;         if (rc != null && rc.Rendering != null)         {             foreach(var parameter in rc.Rendering.Parameters)             {                 collection.Add(parameter.Key, parameter.Value);             }         }         _wrappedProvider = new NameValueCollectionValueProvider(collection, CultureInfo.InvariantCulture);         }     public bool ContainsPrefix(string prefix)     {         return _wrappedProvider.ContainsPrefix(prefix);     }     public ValueProviderResult GetValue(string key)     {         return _wrappedProvider.GetValue(key);     } } In this post I've discussed the MVC IValueProvider used to map data to controller action method arguments and how this can be integrated into your Sitecore 6.6 MVC solution.

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  • Build Dependencies and Silverlight 4

    - by Kyle Burns
    At my current position, I’ve been doing quite a bit of Silverlight development and have also been working with TFS2010 build services to enable continuous integration.  One of the critical pieces of a successful continuous build setup (and also one of the benefits of having one) is that the build system should be able to “get latest” against the source repository and immediately build with no errors.  This can break down both in an automated build scenario and a “new guy” scenario when the solution has external dependencies that may not be present in the build environment. The method that I use to address the dependency issue is to store all of the binaries upon which my solution depends in a folder under the solution root called “Reference Items”.  I keep this folder as part of the solution and check all of the binaries into source control so when I get the latest version of the solution from source control all of the binaries are downloaded to my machine as well and gets me closer to the ideal where a new developer installs the development IDE, get latest and can immediately build and run unit tests before jumping into coding the feature of the day. This all sounds pretty good (and it is), but a little while back I ran into one of those little hiccups that requires a little manual intervention.  The issue that I ran into is that with Silverlight (at least version 4), the behavior of the “Add Reference” command when adding reference to a DLL that is present in the GAC is to omit the HintPath element that it includes with regular .Net projects, so even if the DLL is setting in the Reference Items folder and downloaded to the build machine it cannot be found at compile time and the build will fail. To work around this behavior, you need to be comfortable editing the XML project files generated by Visual Studio (in my case this is typically a .csproj file).  Simply open the project file in your favorite text editor, find the Reference element that refers to the component, and modify the XML to include the HintPath.  Here’s a before and after example of the component that ultimately led me to the investigation behind this post: Before: <Reference Include="Telerik.Windows.Controls, Version=2011.2.920.1040, Culture=neutral, PublicKeyToken=5803cfa389c90ce7, processorArchitecture=MSIL" /> After: <Reference Include="Telerik.Windows.Controls, Version=2011.2.920.1040, Culture=neutral, PublicKeyToken=5803cfa389c90ce7, processorArchitecture=MSIL">       <HintPath>..\Reference Items\Telerik.Windows.Controls.dll</HintPath>     </Reference>

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  • Cant access ephemeral storage on Amazon ubuntu instance

    - by matt burns
    I want to utilise my ephemeral storage as mentioned in this question but I seem to be falling at the first hurdle. I can't even see /mnt: ~$ df -ah Filesystem Size Used Avail Use% Mounted on /dev/xvda1 8.0G 855M 6.8G 12% / proc 0 0 0 - /proc sysfs 0 0 0 - /sys none 0 0 0 - /sys/fs/fuse/connections none 0 0 0 - /sys/kernel/debug none 0 0 0 - /sys/kernel/security udev 288M 8.0K 288M 1% /dev devpts 0 0 0 - /dev/pts tmpfs 119M 152K 118M 1% /run none 5.0M 0 5.0M 0% /run/lock none 296M 0 296M 0% /run/shm This is from a vanilla instance of an ubuntu AMI (12.04-amd64-server-20120424 ami-a29943cb) I'm not bothered about resizing the partition, I just want to be able to use the space for writing temp files.

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  • When is my View too smart?

    - by Kyle Burns
    In this posting, I will discuss the motivation behind keeping View code as thin as possible when using patterns such as MVC, MVVM, and MVP.  Once the motivation is identified, I will examine some ways to determine whether a View contains logic that belongs in another part of the application.  While the concepts that I will discuss are applicable to most any pattern which favors a thin View, any concrete examples that I present will center on ASP.NET MVC. Design patterns that include a Model, a View, and other components such as a Controller, ViewModel, or Presenter are not new to application development.  These patterns have, in fact, been around since the early days of building applications with graphical interfaces.  The reason that these patterns emerged is simple – the code running closest to the user tends to be littered with logic and library calls that center around implementation details of showing and manipulating user interface widgets and when this type of code is interspersed with application domain logic it becomes difficult to understand and much more difficult to adequately test.  By removing domain logic from the View, we ensure that the View has a single responsibility of drawing the screen which, in turn, makes our application easier to understand and maintain. I was recently asked to take a look at an ASP.NET MVC View because the developer reviewing it thought that it possibly had too much going on in the view.  I looked at the .CSHTML file and the first thing that occurred to me was that it began with 40 lines of code declaring member variables and performing the necessary calculations to populate these variables, which were later either output directly to the page or used to control some conditional rendering action (such as adding a class name to an HTML element or not rendering another element at all).  This exhibited both of what I consider the primary heuristics (or code smells) indicating that the View is too smart: Member variables – in general, variables in View code are an indication that the Model to which the View is being bound is not sufficient for the needs of the View and that the View has had to augment that Model.  Notable exceptions to this guideline include variables used to hold information specifically related to rendering (such as a dynamically determined CSS class name or the depth within a recursive structure for indentation purposes) and variables which are used to facilitate looping through collections while binding. Arithmetic – as with member variables, the presence of arithmetic operators within View code are an indication that the Model servicing the View is insufficient for its needs.  For example, if the Model represents a line item in a sales order, it might seem perfectly natural to “normalize” the Model by storing the quantity and unit price in the Model and multiply these within the View to show the line total.  While this does seem natural, it introduces a business rule to the View code and makes it impossible to test that the rounding of the result meets the requirement of the business without executing the View.  Within View code, arithmetic should only be used for activities such as incrementing loop counters and calculating element widths. In addition to the two characteristics of a “Smart View” that I’ve discussed already, this View also exhibited another heuristic that commonly indicates to me the need to refactor a View and make it a bit less smart.  That characteristic is the existence of Boolean logic that either does not work directly with properties of the Model or works with too many properties of the Model.  Consider the following code and consider how logic that does not work directly with properties of the Model is just another form of the “member variable” heuristic covered earlier: @if(DateTime.Now.Hour < 12) {     <div>Good Morning!</div> } else {     <div>Greetings</div> } This code performs business logic to determine whether it is morning.  A possible refactoring would be to add an IsMorning property to the Model, but in this particular case there is enough similarity between the branches that the entire branching structure could be collapsed by adding a Greeting property to the Model and using it similarly to the following: <div>@Model.Greeting</div> Now let’s look at some complex logic around multiple Model properties: @if (ModelPageNumber + Model.NumbersToDisplay == Model.PageCount         || (Model.PageCount != Model.CurrentPage             && !Model.DisplayValues.Contains(Model.PageCount))) {     <div>There's more to see!</div> } In this scenario, not only is the View code difficult to read (you shouldn’t have to play “human compiler” to determine the purpose of the code), but it also complex enough to be at risk for logical errors that cannot be detected without executing the View.  Conditional logic that requires more than a single logical operator should be looked at more closely to determine whether the condition should be evaluated elsewhere and exposed as a single property of the Model.  Moving the logic above outside of the View and exposing a new Model property would simplify the View code to: @if(Model.HasMoreToSee) {     <div>There’s more to see!</div> } In this posting I have briefly discussed some of the more prominent heuristics that indicate a need to push code from the View into other pieces of the application.  You should now be able to recognize these symptoms when building or maintaining Views (or the Models that support them) in your applications.

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  • Why do we (really) program to interfaces?

    - by Kyle Burns
    One of the earliest lessons I was taught in Enterprise development was "always program against an interface".  This was back in the VB6 days and I quickly learned that no code would be allowed to move to the QA server unless my business objects and data access objects each are defined as an interface and have a matching implementation class.  Why?  "It's more reusable" was one answer.  "It doesn't tie you to a specific implementation" a slightly more knowing answer.  And let's not forget the discussion ending "it's a standard".  The problem with these responses was that senior people didn't really understand the reason we were doing the things we were doing and because of that, we were entirely unable to realize the intent behind the practice - we simply used interfaces and had a bunch of extra code to maintain to show for it. It wasn't until a few years later that I finally heard the term "Inversion of Control".  Simply put, "Inversion of Control" takes the creation of objects that used to be within the control (and therefore a responsibility of) of your component and moves it to some outside force.  For example, consider the following code which follows the old "always program against an interface" rule in the manner of many corporate development shops: 1: ICatalog catalog = new Catalog(); 2: Category[] categories = catalog.GetCategories(); In this example, I met the requirement of the rule by declaring the variable as ICatalog, but I didn't hit "it doesn't tie you to a specific implementation" because I explicitly created an instance of the concrete Catalog object.  If I want to test the functionality of the code I just wrote I have to have an environment in which Catalog can be created along with any of the resources upon which it depends (e.g. configuration files, database connections, etc) in order to test my functionality.  That's a lot of setup work and one of the things that I think ultimately discourages real buy-in of unit testing in many development shops. So how do I test my code without needing Catalog to work?  A very primitive approach I've seen is to change the line the instantiates catalog to read: 1: ICatalog catalog = new FakeCatalog();   once the test is run and passes, the code is switched back to the real thing.  This obviously poses a huge risk for introducing test code into production and in my opinion is worse than just keeping the dependency and its associated setup work.  Another popular approach is to make use of Factory methods which use an object whose "job" is to know how to obtain a valid instance of the object.  Using this approach, the code may look something like this: 1: ICatalog catalog = CatalogFactory.GetCatalog();   The code inside the factory is responsible for deciding "what kind" of catalog is needed.  This is a far better approach than the previous one, but it does make projects grow considerably because now in addition to the interface, the real implementation, and the fake implementation(s) for testing you have added a minimum of one factory (or at least a factory method) for each of your interfaces.  Once again, developers say "that's too complicated and has me writing a bunch of useless code" and quietly slip back into just creating a new Catalog and chalking any test failures up to "it will probably work on the server". This is where software intended specifically to facilitate Inversion of Control comes into play.  There are many libraries that take on the Inversion of Control responsibilities in .Net and most of them have many pros and cons.  From this point forward I'll discuss concepts from the standpoint of the Unity framework produced by Microsoft's Patterns and Practices team.  I'm primarily focusing on this library because it questions about it inspired this posting. At Unity's core and that of most any IoC framework is a catalog or registry of components.  This registry can be configured either through code or using the application's configuration file and in the most simple terms says "interface X maps to concrete implementation Y".  It can get much more complicated, but I want to keep things at the "what does it do" level instead of "how does it do it".  The object that exposes most of the Unity functionality is the UnityContainer.  This object exposes methods to configure the catalog as well as the Resolve<T> method which is used to obtain an instance of the type represented by T.  When using the Resolve<T> method, Unity does not necessarily have to just "new up" the requested object, but also can track dependencies of that object and ensure that the entire dependency chain is satisfied. There are three basic ways that I have seen Unity used within projects.  Those are through classes directly using the Unity container, classes requiring injection of dependencies, and classes making use of the Service Locator pattern. The first usage of Unity is when classes are aware of the Unity container and directly call its Resolve method whenever they need the services advertised by an interface.  The up side of this approach is that IoC is utilized, but the down side is that every class has to be aware that Unity is being used and tied directly to that implementation. Many developers don't like the idea of as close a tie to specific IoC implementation as is represented by using Unity within all of your classes and for the most part I agree that this isn't a good idea.  As an alternative, classes can be designed for Dependency Injection.  Dependency Injection is where a force outside the class itself manipulates the object to provide implementations of the interfaces that the class needs to interact with the outside world.  This is typically done either through constructor injection where the object has a constructor that accepts an instance of each interface it requires or through property setters accepting the service providers.  When using dependency, I lean toward the use of constructor injection because I view the constructor as being a much better way to "discover" what is required for the instance to be ready for use.  During resolution, Unity looks for an injection constructor and will attempt to resolve instances of each interface required by the constructor, throwing an exception of unable to meet the advertised needs of the class.  The up side of this approach is that the needs of the class are very clearly advertised and the class is unaware of which IoC container (if any) is being used.  The down side of this approach is that you're required to maintain the objects passed to the constructor as instance variables throughout the life of your object and that objects which coordinate with many external services require a lot of additional constructor arguments (this gets ugly and may indicate a need for refactoring). The final way that I've seen and used Unity is to make use of the ServiceLocator pattern, of which the Patterns and Practices team has also provided a Unity-compatible implementation.  When using the ServiceLocator, your class calls ServiceLocator.Retrieve in places where it would have called Resolve on the Unity container.  Like using Unity directly, it does tie you directly to the ServiceLocator implementation and makes your code aware that dependency injection is taking place, but it does have the up side of giving you the freedom to swap out the underlying IoC container if necessary.  I'm not hugely concerned with hiding IoC entirely from the class (I view this as a "nice to have"), so the single biggest problem that I see with the ServiceLocator approach is that it provides no way to proactively advertise needs in the way that constructor injection does, allowing more opportunity for difficult to track runtime errors. This blog entry has not been intended in any way to be a definitive work on IoC, but rather as something to spur thought about why we program to interfaces and some ways to reach the intended value of the practice instead of having it just complicate your code.  I hope that it helps somebody begin or continue a journey away from being a "Cargo Cult Programmer".

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  • Stop trying to be perfect

    - by Kyle Burns
    Yes, Bob is my uncle too.  I also think the points in the Manifesto for Software Craftsmanship (manifesto.softwarecraftsmanship.org) are all great.  What amazes me is that tend to confuse the term “well crafted” with “perfect”.  I'm about to say something that will make Quality Assurance managers and many development types as well until you think about it as a craftsman – “Stop trying to be perfect”. Now let me explain what I mean.  Building software, as with building almost anything, often involves a series of trade-offs where either one undesired characteristic is accepted as necessary to achieve another desired one (or maybe stave off one that is even less desirable) or a desirable characteristic is sacrificed for the same reasons.  This implies that perfection itself is unattainable.  What is attainable is “sufficient” and I think that this really goes to the heart both of what people are trying to do with Agile and with the craftsmanship movement.  Simply put, sufficient software drives the greatest business value.   I've been in many meetings where “how can we keep anything from ever going wrong” has become the thing that holds us in analysis paralysis.  I've also been the guy trying way too hard to perfect some function to make sure that every edge case is accounted for.  Somewhere in there, something a drill instructor said while I was in boot camp occurred to me.  In response to being asked a question by another recruit having to do with some edge case (I can barely remember the context), he said “What if grasshoppers had machine guns?  Would the birds still **** with them?”  It sounds funny, but there's a lot of wisdom in those words.   “Sufficient” is different for every situation and it’s important to understand what sufficient means in the context of the work you’re doing.  If I’m writing a timesheet application (and please shoot me if I am), I’m going to have a much higher tolerance for imperfection than if you’re writing software to control life support systems on spacecraft.  I’m also likely to have less need for high volume performance than if you’re writing software to control stock trading transactions.   I’d encourage anyone who has read this far to instead of trying to be perfect, try to create software that is sufficient in every way.  If you’re working to make a component that is sufficient “better”, ask yourself if there is any component left that is not yet sufficient.  If the answer is “yes” you’re working on the wrong thing and need to adjust.  If the answer is “no”, why aren’t you shipping and delivering business value?

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  • Obtaining positional information in the IEnumerable Select extension method

    - by Kyle Burns
    This blog entry is intended to provide a narrow and brief look into a way to use the Select extension method that I had until recently overlooked. Every developer who is using IEnumerable extension methods to work with data has been exposed to the Select extension method, because it is a pretty critical piece of almost every query over a collection of objects.  The method is defined on type IEnumerable and takes as its argument a function that accepts an item from the collection and returns an object which will be an item within the returned collection.  This allows you to perform transformations on the source collection.  A somewhat contrived example would be the following code that transforms a collection of strings into a collection of anonymous objects: 1: var media = new[] {"book", "cd", "tape"}; 2: var transformed = media.Select( item => 3: { 4: Media = item 5: } ); This code transforms the array of strings into a collection of objects which each have a string property called Media. If every developer using the LINQ extension methods already knows this, why am I blogging about it?  I’m blogging about it because the method has another overload that I hadn’t seen before I needed it a few weeks back and I thought I would share a little about it with whoever happens upon my blog.  In the other overload, the function defined in the first overload as: 1: Func<TSource, TResult> is instead defined as: 1: Func<TSource, int, TResult>   The additional parameter is an integer representing the current element’s position in the enumerable sequence.  I used this information in what I thought was a pretty cool way to compare collections and I’ll probably blog about that sometime in the near future, but for now we’ll continue with the contrived example I’ve already started to keep things simple and show how this works.  The following code sample shows how the positional information could be used in an alternating color scenario.  I’m using a foreach loop because IEnumerable doesn’t have a ForEach extension, but many libraries do add the ForEach extension to IEnumerable so you can update the code if you’re using one of these libraries or have created your own. 1: var media = new[] {"book", "cd", "tape"}; 2: foreach (var result in media.Select( 3: (item, index) => 4: new { Item = item, Index = index })) 5: { 6: Console.ForegroundColor = result.Index % 2 == 0 7: ? ConsoleColor.Blue : ConsoleColor.Yellow; 8: Console.WriteLine(result.Item); 9: }

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  • How do I start my career on a 3-year-old degree [on hold]

    - by Gabriel Burns
    I received my bachelor's degree in Com S (second major in math) in December 2011. I didn't have the best GPA (I was excellent at programming projects and had a deep understanding of CS concepts, but school is generally not the best format for displaying my strengths), and my only internship was with a now-defunct startup. After graduation I applied for several jobs, had a fair number of interviews, but never got hired. After a while, I got somewhat discouraged, and though I still said I was looking, and occasionally applied for something, my pace slowed down considerably. I remain convinced that software development is the right path for me, and that I could make a real contribution to someones work force, but I'm at a loss as to how I can convince anyone of this. My major problems are as follows. Lack of professional experience-- a problem for every entry-level programmer, I suppose, but everyone seems to want someone with a couple of years under their belt. Rustiness-- I've not really done any programming in about a year, and since school all I've really done is various programming competitions and puzzles. (codechef, hackerrank, etc.) I need a way to sharpen my skills. Long term unemployment-- while I had a basic fast-food job after I graduated, I've been truly unemployed for about a year now. Furthermore, no one has ever hired me as a programmer, and any potential employer is liable to wonder why. Old References-- my references are all college professors and one supervisor from my internship, none of whom I've had any contact with since I graduated. Confidence-- I have no doubt that I could be a good professional programmer, and make just about any employer glad that they hired me, but I'm aware of my red flags as a candidate, and have a hard time heading confidently into an interview. How can I overcome these problems and keep my career from being over before it starts?

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  • Where's the source code?

    - by Kyle Burns
    I've been contacted by several people through this blog asking about the missing source code for the "Beginning Windows 8 Application Development - XAML Edition" book (the book is available at http://www.amazon.com/gp/product/1430245662/http://www.amazon.com/gp/product/1430245662/) and wanted to share this with others who may have come to this blog looking for it but may not have communicated with me.  The publisher (Apress) does know that the source code is not posted on the book's product page and will be correcting it.  Apress is located in New York City and things were slowed down a little bit last week due to the storm, but I've been assured they will be correcting the product page as soon as they can.  Thanks to everyone who has bought the book and I especially appreciate your patience.

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  • Why might changes be populated from one NSManagedObjectContext to another without an explicit merge?

    - by Mike Laurence
    I'm working on an object import feature that utilizes multiple threads/NSManagedObjectContexts, using http://www.mac-developer-network.com/columns/coredata/may2009/ as my guide (note that I am developing for iPhone). For some reason, when I save one of my contexts the other is immediately updated with the changes, even though I have commented out my calls to mergeChangesFromContextDidSaveNotification. Are there any reasons the contexts might be merging into one another without an explicit call? Here a log of what's going on: // 1.) Main context is saved with "Peter Gabriel" // 2.) Test context is created, begins with same contents as main context // 3.) Main context is inserted with "Spoon" // 4.) Test context is inserted with "Phoenix" // Contents at this point: CoreTest[4341:903] Artists in main context: ( "Peter Gabriel", "Spoon" ) CoreTest[4341:903] Artists in test context: ( "Peter Gabriel", "Phoenix" ) // 5.) testContext is saved // New contents of contexts: CoreTest[4341:903] Artists in main context: ( "Peter Gabriel", "Phoenix", "Spoon" ) CoreTest[4341:903] Artists in test context: ( "Peter Gabriel", "Phoenix" ) As you can see, the test context is saved midway through, and the main context suddenly has the new objects from the test context, even though I haven't performed the whole NSManagedObjectContextDidSaveNotification/mergeChangesFromContext combo. My understanding is that no changes will ever be merged unless done so explicitly... does anyone know what's going on here?

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  • How to perform a Linq2Sql query on the following dataset

    - by Bas
    I have the following tables: Person(Id, FirstName, LastName) { (1, "John", "Doe"), (2, "Peter", "Svendson") (3, "Ola", "Hansen") (4, "Mary", "Pettersen") } Sports(Id, Name) { (1, "Tennis") (2, "Soccer") (3, "Hockey") } SportsPerPerson(Id, PersonId, SportsId) { (1, 1, 1) (2, 1, 3) (3, 2, 2) (4, 2, 3) (5, 3, 2) (6, 4, 1) (7, 4, 2) (8, 4, 3) } Looking at the tables, we can conclude the following facts: John plays Tennis John plays Hockey Peter plays Soccer Peter plays Hockey Ola plays Soccer Mary plays Tennis Mary plays Soccer Mary plays Hockey Now I would like to create a Linq2Sql query which retrieves the following: Get all Persons who play Hockey and Soccer Executing the query should return: Peter and Mary Anyone has any idea's on how to approach this in Linq2Sql?

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  • Eye-Infinity across 3 displays with a Radeon 6800

    - by Peter G Mac.
    So I purchased a computer recently and have been trying to customise the display. Radeon HD 6800 series Ubuntu 10.10. I have three 22inch 1080P lcd monitors that are mounted together. Everything is working smooth. How do I get the 'big-desktop' display where I have one enormous display across all monitors? Linux - ATI Catalyst Control Center 11.2 does not give me an option to 'group' my profiles like the pictures on their site show with Windows. I have been searching all over for help. Much Obliged, -Peter

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  • Concatenate Gridview Data

    - by zahid mahmood
    I have a gridview with following Data CustomerName item qty tom sugar 1 kg Peter Rice 2 Kg Jhone Sugar .5 kg tom Rice 5 Kg Peter Tea .5 Kg tom Tea 1 kg now I want to display data with the following format: tom sugar 1kg, Rice 5 kg, Tea 1 kg Peter Rice 1kg, Tea .5 kg Jhone Sugar .5kg how to achieve this

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  • PHP: form action on same page, still show same until refresh

    - by Karem
    Yes, Im having a little edit profile page, index.php?mode=profile. Lets take the username in the editprofile form as example. The username is already in the username-field. So i changed from "Peter" to "Tom" and press save. The action is ?mode=profile&edit=true. So now when i have pressed save it has updated the column in the db from Peter to Tom. But this field keeps having the value "Peter" until if i do press refresh (or f5), then "Tom" will appear. Like it hasnt updated in the database anything, although it did but it still shows Peter until next refresh.. like it caches, but it shouldnt cache nothing? Any help on this? Is it because its on the same "page" / file? what can i do

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