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  • How to Inserting message into View that depends on session value. ASP.NET MVC. Best practice

    - by Andrew Florko
    User have to populate multistep questionnaire web-forms and step messages depend on the option chosen by user at the very beginning. Messages are stored in web.config file. I use asp.net mvc project, strong typed views and keep business logic separated from controller in static class. I don't want to make business logic dependency on web.config. Well, I have to insert message into view that depends on session value. There are at least 2 options how to implement this: View model has property that is populated in controller/businessLogic and rendered in view like <%: Model.HelpMessage1 %>. I have to pass web.config values from controller to businessLogic that makes business logic methods signature too complex. I don't want to make configuration source abstract (in order to let business logic read configuration values from its methods directly) also. Create static helper class that is called from view like <%: ViewHelper.HelpMessage1(Model.Option1) %>. But in this case logic what to show seems to be separated into two classes: business logic & viewHelper. What will you suggest? Thank you in advance!

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  • Coding style in .NET: whether to refactor into new method or not?

    - by Dione
    Hi As you aware, in .NET code-behind style, we already use a lot of function to accommodate those _Click function, _SelectedIndexChanged function etc etc. In our team there are some developer that make a function in the middle of .NET function, for example: public void Button_Click(object sender, EventArgs e) {     some logic here..     some logic there..     DoSomething();     DoSomethingThere();     another logic here..     DoOtherSomething(); } private void DoSomething() { } private void DoSomethingThere() { } private void DoOtherSomething() { } public void DropDown_SelectedIndexChanged() { } public void OtherButton_Click() { } and the function listed above is only used once in that function and not used anywhere else in the page, or called from other part of the solution. They said it make the code more tidier by grouping them and extract them into additional sub-function. I can understand if the sub-function is use over and over again in the code, but if it is only use once, then I think it is not really a good idea to extract them into sub-function, as the code getting bigger and bigger, when you look into the page and trying to understand the logic or to debug by skimming through line by line, it will make you confused by jumping from main function to the sub-function then to main function and to sub-function again. I know this kind of grouping by method is better when you writing old ASP or Cold fusion style, but I am not sure if this kind of style is better for .NET or not. Question is: which is better when you developing .NET, is grouping similar logic into a sub-method better (although they only use once), or just put them together inside main function and add //explanation here on the start of the logic is better? Hope my question is clear enough. Thanks.

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  • How to safely reboot via First Boot script

    - by unixman
    With the cost and performance benefits of the SPARC T4 and SPARC T5 systems undeniably validated, the banking sector is actively moving to Solaris 11.  I was recently asked to help a banking customer of ours look at migrating some of their Solaris 10 logic over to Solaris 11.  While we've introduced a number of holistic improvements in Solaris 11, in terms of how we ease long-term software lifecycle management, it is important to appreciate that customers may not be able to move all of their Solaris 10 scripts and procedures at once; there are years of scripts that reflect fine-tuned requirements of proprietary banking software that gets layered on top of the operating system. One of these requirements is to go through a cycle of reboots, after the system is installed, in order to ensure appropriate software dependencies and various configuration files are in-place. While Solaris 10 introduced a facility that aids here, namely SMF, many of our customers simply haven't yet taken the time to take advantage of this - proceeding with logic that, while functional, without further analysis has an appearance of not being optimal in terms of taking advantage of all the niceties bundled in Solaris 11 at no extra cost. When looking at Solaris 11, we recognize that one of the vehicles that bridges the gap between getting the operating system image payload delivered, and the customized banking software installed, is a notion of a First Boot script.  I had a working example of this at one of the Oracle OpenWorld sessions a few years ago - we've since improved our documentation and have introduced sections where this is described in better detail.   If you're looking at this for the first time and you've not worked with IPS and SMF previously, you might get the sense that the tasks are daunting.   There is a set of technologies involved that are jointly engineered in order to make the process reliable, predictable and extensible. As you go down the path of writing your first boot script, you'll be faced with a need to wrap it into a SMF service and then packaged into a IPS package. The IPS package would then need to be placed onto your IPS repository, in order to subsequently be made available to all of your AI (Automated Install) clients (i.e. the systems that you're installing Solaris and your software onto).     With this blog post, I wanted to create a single place that outlines the entire process (simplistically), and provide a hint of how a good old "at" command may make the requirement of forcing an initial reboot handy. The syntax and references to commands here is based on running this on a version of Solaris 11 that has been updated since its initial release in 2011 (i.e. I am writing this on Solaris 11.1) Assuming you've built an AI server (see this How To article for an example), you might be asking yourself: "Ok, I've got some logic that I need executed AFTER Solaris is deployed and I need my own little script that would make that happen. How do I go about hooking that script into the Solaris 11 AI framework?"  You might start here, in Chapter 13 of the "Installing Oracle Solaris 11.1 Systems" guide, which talks about "Running a Custom Script During First Boot".  And as you do, you'll be confronted with command that might be unfamiliar to you if you're new to Solaris 11, like our dear new friend: svcbundle svcbundle is an aide to creating manifests and profiles.  It is awesome, but don't let its awesomeness overwhelm you. (See this How To article by my colleague Glynn Foster for a nice working example).  In order to get your script's logic integrated into the Solaris 11 deployment process, you need to wrap your (shell) script into 2 manifests -  a SMF service manifest and a IPS package manifest.  ....and if you're new to XML, well then -- buckle up We have some examples of small first boot scripts shown here, as templates to build upon. Necessary structure of the script, particularly in leveraging SMF interfaces, is key. I won't go into that here as that is covered nicely in the doc link above.    Let's say your script ends up looking like this (btw: if things appear to be cut-off in your browser, just select them, copy and paste into your editor and it'll be grabbed - the source gets captured eventhough the browser may not render it "correctly" - ah, computers). #!/bin/sh # Load SMF shell support definitions . /lib/svc/share/smf_include.sh # If nothing to do, exit with temporary disable completed=`svcprop -p config/completed site/first-boot-script-svc:default` [ "${completed}" = "true" ] && \ smf_method_exit $SMF_EXIT_TEMP_DISABLE completed "Configuration completed" # Obtain the active BE name from beadm: The active BE on reboot has an R in # the third column of 'beadm list' output. Its name is in column one. bename=`beadm list -Hd|nawk -F ';' '$3 ~ /R/ {print $1}'` beadm create ${bename}.orig echo "Original boot environment saved as ${bename}.orig" # ---- Place your one-time configuration tasks here ---- # For example, if you have to pull some files from your own pre-existing system: /usr/bin/wget -P /var/tmp/ $PULL_DOWN_ADDITIONAL_SCRIPTS_FROM_A_CORPORATE_SYSTEM /usr/bin/chmod 755 /var/tmp/$SCRIPTS_THAT_GOT_PULLED_DOWN_IN_STEP_ABOVE # Clearly the above 2 lines represent some logic that you'd have to customize to fit your needs. # # Perhaps additional things you may want to do here might be of use, like # (gasp!) configuring ssh server for root login and X11 forwarding (for testing), and the like... # # Oh and by the way, after we're done executing all of our proprietary scripts we need to reboot # the system in accordance with our operational software requirements to ensure all layered bits # get initialized properly and pull-in their own modules and components in the right sequence, # subsequently. # We need to set a "time bomb" reboot, that would take place upon completion of this script. # We already know that *this* script depends on multi-user-server SMF milestone, so it should be # safe for us to schedule a reboot for 5 minutes from now. The "at" job get scheduled in the queue # while our little script continues thru the rest of the logic. /usr/bin/at now + 5 minutes <<REBOOT /usr/bin/sync /usr/sbin/reboot REBOOT # ---- End of your customizations ---- # Record that this script's work is done svccfg -s site/first-boot-script-svc:default setprop config/completed = true svcadm refresh site/first-boot-script-svc:default smf_method_exit $SMF_EXIT_TEMP_DISABLE method_completed "Configuration completed"  ...and you're happy with it and are ready to move on. Where do you go and what do you do? The next step is creating the IPS package for your script. Since running the logic of your script constitutes a service, you need to create a service manifest. This is described here, in the middle of Chapter 13 of "Creating an IPS package for the script and service".  Assuming the name of your shell script is first-boot-script.sh, you could end up doing the following: $ cd some_working_directory_for_this_project$ mkdir -p proto/lib/svc/manifest/site$ mkdir -p proto/opt/site $ cp first-boot-script.sh proto/opt/site  Then you would create the service manifest  file like so: $ svcbundle -s service-name=site/first-boot-script-svc \ -s start-method=/opt/site/first-boot-script.sh \ -s instance-property=config:completed:boolean:false -o \ first-boot-script-svc-manifest.xml   ...as described here, and place it into the directory hierarchy above. But before you place it into the directory, make sure to inspect the manifest and adjust the appropriate service dependencies.  That is to say, you want to properly specify what milestone should be reached before your service runs.  There's a <dependency> section that looks like this, before you modify it: <dependency restart_on="none" type="service" name="multi_user_dependency" grouping="require_all"> <service_fmri value="svc:/milestone/multi-user"/>  </dependency>  So if you'd like to have your service run AFTER the multi-user-server milestone has been reached (i.e. later, as multi-user-server has more dependencies then multi-user and our intent to reboot the system may have significant ramifications if done prematurely), you would modify that section to read:  <dependency restart_on="none" type="service" name="multi_user_server_dependency" grouping="require_all"> <service_fmri value="svc:/milestone/multi-user-server"/>  </dependency> Save the file and validate it: $ svccfg validate first-boot-script-svc-manifest.xml Assuming there are no errors returned, copy the file over into the directory hierarchy: $ cp first-boot-script-svc-manifest.xml proto/lib/svc/manifest/site Now that we've created the service manifest (.xml), create the package manifest (.p5m) file named: first-boot-script.p5m.  Populate it as follows: set name=pkg.fmri value=first-boot-script-AT-1-DOT-0,5.11-0 set name=pkg.summary value="AI first-boot script" set name=pkg.description value="Script that runs at first boot after AI installation" set name=info.classification value=\ "org.opensolaris.category.2008:System/Administration and Configuration" file lib/svc/manifest/site/first-boot-script-svc-manifest.xml \ path=lib/svc/manifest/site/first-boot-script-svc-manifest.xml owner=root \ group=sys mode=0444 dir path=opt/site owner=root group=sys mode=0755 file opt/site/first-boot-script.sh path=opt/site/first-boot-script.sh \ owner=root group=sys mode=0555 Now we are going to publish this package into a IPS repository. If you don't have one yet, don't worry. You have 2 choices: You can either  publish this package into your mirror of the Oracle Solaris IPS repo or create your own customized repo.  The best practice is to create your own customized repo, leaving your mirror of the Oracle Solaris IPS repo untouched.  From this point, you have 2 choices as well - you can either create a repo that will be accessible by your clients via HTTP or via NFS.  Since HTTP is how the default Solaris repo is accessed, we'll go with HTTP for your own IPS repo.   This nice and comprehensive How To by Albert White describes how to create multiple internal IPS repos for Solaris 11. We'll zero in on the basic elements for our needs here: We'll create the IPS repo directory structure hanging off a separate ZFS file system, and we'll tie it into an instance of pkg.depotd. We do this because we want our IPS repo to be accessible to our AI clients through HTTP, and the pkg.depotd SMF service bundled in Solaris 11 can help us do this. We proceed as follows: # zfs create rpool/export/MyIPSrepo # pkgrepo create /export/MyIPSrepo # svccfg -s pkg/server add MyIPSrepo # svccfg -s pkg/server:MyIPSrepo addpg pkg application # svccfg -s pkg/server:MyIPSrepo setprop pkg/port=10081 # svccfg -s pkg/server:MyIPSrepo setprop pkg/inst_root=/export/MyIPSrepo # svccfg -s pkg/server:MyIPSrepo addpg general framework # svccfg -s pkg/server:MyIPSrepo addpropvalue general/complete astring: MyIPSrepo # svccfg -s pkg/server:MyIPSrepo addpropvalue general/enabled boolean: true # svccfg -s pkg/server:MyIPSrepo setprop pkg/readonly=true # svccfg -s pkg/server:MyIPSrepo setprop pkg/proxy_base = astring: http://your_internal_websrvr/MyIPSrepo # svccfg -s pkg/server:MyIPSrepo setprop pkg/threads = 200 # svcadm refresh application/pkg/server:MyIPSrepo # svcadm enable application/pkg/server:MyIPSrepo Now that the IPS repo is created, we need to publish our package into it: # pkgsend publish -d ./proto -s /export/MyIPSrepo first-boot-script.p5m If you find yourself making changes to your script, remember to up-rev the version in the .p5m file (which is your IPS package manifest), and re-publish the IPS package. Next, you need to go to your AI install server (which might be the same machine) and modify the AI manifest to include a reference to your newly created package.  We do that by listing an additional publisher, which would look like this (replacing the IP address and port with your own, from the "svccfg" commands up above): <publisher name="firstboot"> <origin name="http://192.168.1.222:10081"/> </publisher>  Further down, in the  <software_data action="install">  section add: <name>pkg:/first-boot-script</name> Make sure to update your Automated Install service with the new AI manifest via installadm update-manifest command.  Don't forget to boot your client from the network to watch the entire process unfold and your script get tested.  Once the system makes the initial reboot, the first boot script will be executed and whatever logic you've specified in it should be executed, too, followed by a nice reboot. When the system comes up, your service should stay in a disabled state, as specified by the tailing lines of your SMF script - this is normal and should be left as is as it helps provide an auditing trail for you.   Because the reboot is quite a significant action for the system, you may want to add additional logic to the script that actually places and then checks for presence of certain lock files in order to avoid doing a reboot unnecessarily. You may also want to, alternatively, remove the SMF service entirely - if you're unsure of the potential for someone to try and accidentally enable that service -- eventhough its role in life is to only run once upon the system's first boot. That is how I spent a good chunk of my pre-Halloween time this week, hope yours was just as SPARCkly^H^H^H^H fun!    

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  • ASP.NET XML parsing error only on FireFox..

    - by Broken Link
    I get this wired error only when I try to access the web page in FireFox.. IE works just fine.. XML Parsing Error: not well-formed Location: http://localhost/site/Home.aspx Line Number 1, Column 2:<%@ Page Language="C#" MasterPageFile="~/Site1.Master" AutoEventWireup="true" CodeBehind="Home.aspx.cs" Am I missing something?

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  • Fluent | Nhibernate multiple inheritance mapping?

    - by Broken Pipe
    I'm trying to map this classes: public interface IBusinessObject { Guid Id { get; set; } } public class Product { public virtual Guid Id { get; set; } public virtual int ProductTypeId { get; set; } } public class ProductWeSell : Product, IBusinessObject { } public class ProductWeDontSell : Product { } Using this Fluent mapping code: public class IBusinessObjectMap : ClassMap<IBusinessObject> { public IBusinessObjectMap() { Id(t => t.Id).GeneratedBy.Guid(); Table("BusinessObject"); } } public class ProductMap : ClassMap<Product> { public ProductMap() { Id(t => t.Id); DiscriminateSubClassesOnColumn("ProductTypeId", "null").Nullable(); } } public class ProductWeSellMap : SubclassMap<ProductWeSell> { public ProductWeSellMap() { DiscriminatorValue(1); KeyColumn("Id"); } } public class ProductWeDontSellMap : SubclassMap<ProductWeDontSell> { public ProductWeDontSellMap() { DiscriminatorValue(2); KeyColumn("Id"); } } But I get {"Duplicate class/entity mapping ProductWeSell"} error. And if we take a look at generated HBM, indeed it's duplicated, but i have no idea how to write this mapping without duplicating it if it's possible at all. Produced hbm: <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2"> <class xmlns="urn:nhibernate-mapping-2.2" name="IBusinessObject" table="BusinessObject"> <joined-subclass name="ProductWeSell" table="ProductWeSell"/> </class> </hibernate-mapping> <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2"> <class xmlns="urn:nhibernate-mapping-2.2" discriminator-value="null" name="Product" table="Product"> <discriminator type="String"> <column name="ProductTypeId" not-null="false" /> </discriminator> <subclass name="ProductWeDontSell" discriminator-value="2" /> <subclass name="ProductWeSell" discriminator-value="1" /> </class> </hibernate-mapping> So far I was unable to figure out how to map this using fluent Nhibernate (i haven't tried mapping this using hmb files). Any help appreciated Fluent or HBM files. The thing I'm trying to solve look identical to this topic: NHibernate inheritance mapping question

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  • Nant task sysinfo verbose - fails

    - by Broken Link
    Nant.core.dll : 0.86.2898.0 I can not get the following tag working on my machine. <sysinfo verbose="true" /> <sysinfo /> It gives me the following error. If I comment out those two lines I'm able to build. I google'd but not much help. Any idea? NAnt 0.85 (Build 0.85.1932.0; rc3; 4/16/2005) Copyright (C) 2001-2005 Gerry Shaw http://nant.sourceforge.net Buildfile: file:///C:/xyz/source/Default.build Target framework: Microsoft .NET Framework 1.1 Target(s) specified: all [tstamp] Thursday, July 30, 2009 3:10:24 PM. [sysinfo] Setting system information properties under sys.* BUILD FAILED Property name 'sys.env.Zen Managed Workstation' is invalid. Total time: 0 seconds.

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  • URL with no query parameters - How to distinguish.

    - by Broken Link
    Env: .NET 1.1 I got into this situation. Where I need to give a URL that someone could redirect them to our page. When they redirect they also need to tell us, what message I need to display on the page. Initially I thought of something like this. http://example.com/a.aspx?reason=100 http://example.com/a.aspx?reason=101 ... http://example.com/a.aspx?reason=115 So when we get this url based on 'reason' we can display different message. But the problem turns out to be that they can not send any query parameters at all. They want 15 difference URL's since they can't send query params. It doesn't make any sense to me to created 15 pages just to display a message. Any smart ideas,that have one URL and pass the 'reason' thru some means? EDIT: Options I'm thinking based on Answers Try HttpRequest.PathInfo or Second option I was thinking was to have a httphanlder read read the path like this - HttpContext.Request.Path based on path act. Ofcourse I will have some 15 entries like this in web.config. <add verb="*" path="reason1.ashx" type="WebApplication1.Class1, WebApplication1" /> <add verb="*" path="reason2.ashx" type="WebApplication1.Class1, WebApplication1" /> Does that look clean?

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  • NHibernate parent-childs save redundant sql update executed

    - by Broken Pipe
    I'm trying to save (insert) parent object with a collection of child objects, all objects are new. I prefer to manually specify what to save\update and when so I do not use any cascade saves in mappings and flush sessions by myself. So basically I save this object graph like: session.Save(Parent) foreach (var child in Parent.Childs) { session.Save(child); } session.Flush() I expect this code to insert Parent row, then each child row, however NHibernate executes this SQL: INSERT INTO PARENT.... INSERT INTO CHILD .... UPDATE CHILD SET ParentId=@1 WHERE Id=@2 This update statement is absolutely unnecessary, ParentId was already set correctly in INSERT. How do I get rid of it? Performance is very important for me.

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  • How to implement GCM in Google AppEngine?

    - by Broken System
    I'm a PHP Developer and Web Designer. In my work a partner asked me if I could set up a Google Cloud Messaging server. I read the documentation but couldn't find a clear tutorial to set up this server. I got no knowleadge about Java so it makes my job harder. I could "compile" a war file using ant as GCM Demo Tutorial says. But I can't deploy it to my AppEngine server to try it out (It's my first time using AppEngine too). Could you give me some steps to create my own GCM server? Sorry about my bad english. Thanks!

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  • ControlTemplate for ItemsControl with remove button near each item

    - by Broken Pipe
    I'm trying to figure out hot to create ItemsControl which contains Button near each Item, clicking on it removes this item from ItemsControl. I'm new to Silverlight|WPF is it possible to create this using just ControlTemplate? I tried to create inherited ListBox with ControlTemplate that renders button near each item and then i was supposed to hook to click event get item and remove it, but I neither found a way to render button near each item, neither how to subscribe to events from ControlTemplate ;-)

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  • Basic data alignment question

    - by Broken Logic
    I've been playing around to see how my computer works under the hood. What I'm interested in is seeing is what happens on the stack inside a function. To do this I've written the following toy program: #include <stdio.h> void __cdecl Test1(char a, unsigned long long b, char c) { char c1; unsigned long long b1; char a1; c1 = 'b'; b1 = 4; a1 = 'r'; printf("%d %d - %d - %d %d Total: %d\n", (long)&b1 - (long)&a1, (long)&c1 - (long)&b1, (long)&a - (long)&c1, (long)&b - (long)&a, (long)&c - (long)&b, (long)&c - (long)&a1 ); }; struct TestStruct { char a; unsigned long long b; char c; }; void __cdecl Test2(char a, unsigned long long b, char c) { TestStruct locals; locals.a = 'b'; locals.b = 4; locals.c = 'r'; printf("%d %d - %d - %d %d Total: %d\n", (long)&locals.b - (long)&locals.a, (long)&locals.c - (long)&locals.b, (long)&a - (long)&locals.c, (long)&b - (long)&a, (long)&c - (long)&b, (long)&c - (long)&locals.a ); }; int main() { Test1('f', 0, 'o'); Test2('f', 0, 'o'); return 0; } And this spits out the following: 9 19 - 13 - 4 8 Total: 53 8 8 - 24 - 4 8 Total: 52 The function args are well behaved but as the calling convention is specified, I'd expect this. But the local variables are a bit wonky. My question is, why wouldn't these be the same? The second call seems to produce a more compact and better aligned stack. Looking at the ASM is unenlightening (at least to me), as the variable addresses are still aliased there. So I guess this is really a question about the assembler itself allocates the stack to local variables. I realise that any specific answer is likely to be platform specific. I'm more interested in a general explanation unless this quirk really is platform specific. For the record though, I'm compiling with VS2010 on a 64bit Intel machine.

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  • Jquery dialog box - doesn't fade out before closing

    - by Broken Link
    I have div(box) on my page and I'm using this script to display div as dialog box. Inside that div I have a hyper link, On click of the hyper link I want to fade out the dialog box and close.. The content of the dialog fades out, but the border of the dialog box remains same. If I add $("#box").dialog('close') to the click function after fadeto there is no effect.. it just closes the dialog box completely. Any help? using jquery-ui-1.7.2 <script type="text/javascript"> $(document).ready(function(){ $("a#later").click(function () { $("#box").fadeTo('slow', 0); }) }); $(function () { $("#box").dialog({ autoOpen: true, width: 500, modal: true, }); }); </script>

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  • How can I keep the the logic to translate a ViewModel's values to a Where clause to apply to a linq query out of My Controller?

    - by Mr. Manager
    This same problem keeps cropping up. I have a viewModel that doesn't have any persistent backing. It is just a ViewModel to generate a search input form. I want to build a large where clause from the values the user entered. If the Action Accepts as a parameter SearchViewModel How do I do this without passing my viewModel to my service layer? Service shouldn't know about ViewModels right? Oh and if I serialize it, then it would be a big string and the key/values would be strongly typed. SearchViewModel this is just a snippet. [Display(Name="Address")] public string AddressKeywords { get; set; } /// <summary> /// Gets or sets the census. /// </summary> public string Census { get; set; } /// <summary> /// Gets or sets the lot block sub. /// </summary> public string LotBlockSub { get; set; } /// <summary> /// Gets or sets the owner keywords. /// </summary> [Display(Name="Owner")] public string OwnerKeywords { get; set; } In my controller action I was thinking of something like this. but I would think all this logic doesn't belong in my Controller. ActionResult GetSearchResults(SearchViewModel model){ var query = service.GetAllParcels(); if(model.Census != null){ query = query.Where(x=>x.Census == model.Census); } if (model.OwnerKeywords != null){ query = query.Where(x=>x.Owners == model.OwnerKeywords); } return View(query.ToList()); }

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  • SQL SERVER – Validating Unique Columnname Across Whole Database

    - by pinaldave
    I sometimes come across very strange requirements and often I do not receive a proper explanation of the same. Here is the one of those examples. Asker: “Our business requirement is when we add new column we want it unique across current database.” Pinal: “Why do you have such requirement?” Asker: “Do you know the solution?” Pinal: “Sure I can come up with the answer but it will help me to come up with an optimal answer if I know the business need.” Asker: “Thanks – what will be the answer in that case.” Pinal: “Honestly I am just curious about the reason why you need your column name to be unique across database.” (Silence) Pinal: “Alright – here is the answer – I guess you do not want to tell me reason.” Option 1: Check if Column Exists in Current Database IF EXISTS (  SELECT * FROM sys.columns WHERE Name = N'NameofColumn') BEGIN SELECT 'Column Exists' -- add other logic END ELSE BEGIN SELECT 'Column Does NOT Exists' -- add other logic END Option 2: Check if Column Exists in Current Database in Specific Table IF EXISTS (  SELECT * FROM sys.columns WHERE Name = N'NameofColumn' AND OBJECT_ID = OBJECT_ID(N'tableName')) BEGIN SELECT 'Column Exists' -- add other logic END ELSE BEGIN SELECT 'Column Does NOT Exists' -- add other logic END I guess user did not want to share the reason why he had a unique requirement of having column name unique across databases. Here is my question back to you – have you faced a similar situation ever where you needed unique column name across a database. If not, can you guess what could be the reason for this kind of requirement?  Additional Reference: SQL SERVER – Query to Find Column From All Tables of Database Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL System Table, SQL Tips and Tricks, T SQL, Technology

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  • Input of mouseclick not always registered in XNA Update method

    - by LordrAider
    I have a problem that not all inputs of my mouse events seem to be registered. The update logic is checking a 2 dimensional array of 10x10 . It's logic for a jewel matching game. So when i switch my jewel I can't click on another jewel for like half a second. I tested it with a click counter variable and it doesn't hit the debugger when i click the second time after the jewel switch. Only if I do the second click after waiting half a second longer. Could it be that the update logic is too heavy that while he is executing update logic my click is happening and he doesn't register it? What am I not seeing here :)? Or doing wrong. It is my first game. My function of the update methode looks like this. public void UpdateBoard() { MouseState currentMouseState; currentMouseState = Mouse.GetState(); if (currentMouseState.LeftButton == ButtonState.Pressed && prevMouseState.LeftButton != ButtonState.Pressed) { UpdatingLogic = true; // this.CheckDropJewels(currentMouseState); //this.CheckMatches(3); //this.RemoveMatches(); this.CheckForSwitch(currentMouseState); this.MarkJewel(currentMouseState); UpdatingLogic = false; //reIndexMissingJewels = true; reIndexSwitchedJewels = true; } prevMouseState = currentMouseState; this.ReIndex(); this.UpdateJewels(); }

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  • Avoiding bloated Domain Objects

    - by djcredo
    We're trying to move data from our bloated Service layer into our Domain layer using a DDD approach. We currently have a lot of business logic in our services, which is spread out all over the place and doesn't benefit from inheritance. We have a central Domain class which is the focus of most of our work - a Trade. The Trade object will know how to price itself, how to estimate risk, validate itself, etc. We can then replace conditionals with polymorphism. Eg: SimpleTrade will price itself one way, but ComplexTrade will price itself another. However, we are worried that this will bloat the Trade class(s). It really should be in charge of its own processing but the class size is going to increase exponentially as more features are added. So we have choices: Put processing logic in Trade class. Processing logic is now polymorphic based on the type of the trade, but Trade class is now has multiple responsibilites (pricing, risk, etc) and is large Put processing logic into other class such as TradePricingService. No longer polymorphic with the Trade inheritance tree, but classes are smaller and easier to test. What would be the suggested approach?

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  • Model View Controller² [closed]

    - by user694971
    I am working on a quite complex web application in Go and I tried to stay in an MVC pattern. However, I ended up having a structure isomorphic to this: /boilerplate The usual boilerplate an application needs to survive in the wilderness /db Layer talking to an SQL DB /helpers Helpers /logic Backend logic, not directly affiliated with any routes, sessions etc. /templates View /web Glue between /logic and /templates. In more dynamic languages the size of /web would be next to zero. But Go doesn't exactly have a RoR integrated so I need a lot of helper structures to feed the templates with data, to process GET/POST parameters and session information. I remember once reading about patterns similar to MVC with one extra letter but Wiki-searching I couldn't find it right now. (BTW currently /logic also contains data retrieval from API services to fill some hash maps; this is no simple task, but that probably belongs into the model, right?) So question: is this structure considered sane? Or does it need some bending to be tagged MVC app?

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  • The Incremental Architect&rsquo;s Napkin - #5 - Design functions for extensibility and readability

    - by Ralf Westphal
    Originally posted on: http://geekswithblogs.net/theArchitectsNapkin/archive/2014/08/24/the-incremental-architectrsquos-napkin---5---design-functions-for.aspx The functionality of programs is entered via Entry Points. So what we´re talking about when designing software is a bunch of functions handling the requests represented by and flowing in through those Entry Points. Designing software thus consists of at least three phases: Analyzing the requirements to find the Entry Points and their signatures Designing the functionality to be executed when those Entry Points get triggered Implementing the functionality according to the design aka coding I presume, you´re familiar with phase 1 in some way. And I guess you´re proficient in implementing functionality in some programming language. But in my experience developers in general are not experienced in going through an explicit phase 2. “Designing functionality? What´s that supposed to mean?” you might already have thought. Here´s my definition: To design functionality (or functional design for short) means thinking about… well, functions. You find a solution for what´s supposed to happen when an Entry Point gets triggered in terms of functions. A conceptual solution that is, because those functions only exist in your head (or on paper) during this phase. But you may have guess that, because it´s “design” not “coding”. And here is, what functional design is not: It´s not about logic. Logic is expressions (e.g. +, -, && etc.) and control statements (e.g. if, switch, for, while etc.). Also I consider calling external APIs as logic. It´s equally basic. It´s what code needs to do in order to deliver some functionality or quality. Logic is what´s doing that needs to be done by software. Transformations are either done through expressions or API-calls. And then there is alternative control flow depending on the result of some expression. Basically it´s just jumps in Assembler, sometimes to go forward (if, switch), sometimes to go backward (for, while, do). But calling your own function is not logic. It´s not necessary to produce any outcome. Functionality is not enhanced by adding functions (subroutine calls) to your code. Nor is quality increased by adding functions. No performance gain, no higher scalability etc. through functions. Functions are not relevant to functionality. Strange, isn´t it. What they are important for is security of investment. By introducing functions into our code we can become more productive (re-use) and can increase evolvability (higher unterstandability, easier to keep code consistent). That´s no small feat, however. Evolvable code can hardly be overestimated. That´s why to me functional design is so important. It´s at the core of software development. To sum this up: Functional design is on a level of abstraction above (!) logical design or algorithmic design. Functional design is only done until you get to a point where each function is so simple you are very confident you can easily code it. Functional design an logical design (which mostly is coding, but can also be done using pseudo code or flow charts) are complementary. Software needs both. If you start coding right away you end up in a tangled mess very quickly. Then you need back out through refactoring. Functional design on the other hand is bloodless without actual code. It´s just a theory with no experiments to prove it. But how to do functional design? An example of functional design Let´s assume a program to de-duplicate strings. The user enters a number of strings separated by commas, e.g. a, b, a, c, d, b, e, c, a. And the program is supposed to clear this list of all doubles, e.g. a, b, c, d, e. There is only one Entry Point to this program: the user triggers the de-duplication by starting the program with the string list on the command line C:\>deduplicate "a, b, a, c, d, b, e, c, a" a, b, c, d, e …or by clicking on a GUI button. This leads to the Entry Point function to get called. It´s the program´s main function in case of the batch version or a button click event handler in the GUI version. That´s the physical Entry Point so to speak. It´s inevitable. What then happens is a three step process: Transform the input data from the user into a request. Call the request handler. Transform the output of the request handler into a tangible result for the user. Or to phrase it a bit more generally: Accept input. Transform input into output. Present output. This does not mean any of these steps requires a lot of effort. Maybe it´s just one line of code to accomplish it. Nevertheless it´s a distinct step in doing the processing behind an Entry Point. Call it an aspect or a responsibility - and you will realize it most likely deserves a function of its own to satisfy the Single Responsibility Principle (SRP). Interestingly the above list of steps is already functional design. There is no logic, but nevertheless the solution is described - albeit on a higher level of abstraction than you might have done yourself. But it´s still on a meta-level. The application to the domain at hand is easy, though: Accept string list from command line De-duplicate Present de-duplicated strings on standard output And this concrete list of processing steps can easily be transformed into code:static void Main(string[] args) { var input = Accept_string_list(args); var output = Deduplicate(input); Present_deduplicated_string_list(output); } Instead of a big problem there are three much smaller problems now. If you think each of those is trivial to implement, then go for it. You can stop the functional design at this point. But maybe, just maybe, you´re not so sure how to go about with the de-duplication for example. Then just implement what´s easy right now, e.g.private static string Accept_string_list(string[] args) { return args[0]; } private static void Present_deduplicated_string_list( string[] output) { var line = string.Join(", ", output); Console.WriteLine(line); } Accept_string_list() contains logic in the form of an API-call. Present_deduplicated_string_list() contains logic in the form of an expression and an API-call. And then repeat the functional design for the remaining processing step. What´s left is the domain logic: de-duplicating a list of strings. How should that be done? Without any logic at our disposal during functional design you´re left with just functions. So which functions could make up the de-duplication? Here´s a suggestion: De-duplicate Parse the input string into a true list of strings. Register each string in a dictionary/map/set. That way duplicates get cast away. Transform the data structure into a list of unique strings. Processing step 2 obviously was the core of the solution. That´s where real creativity was needed. That´s the core of the domain. But now after this refinement the implementation of each step is easy again:private static string[] Parse_string_list(string input) { return input.Split(',') .Select(s => s.Trim()) .ToArray(); } private static Dictionary<string,object> Compile_unique_strings(string[] strings) { return strings.Aggregate( new Dictionary<string, object>(), (agg, s) => { agg[s] = null; return agg; }); } private static string[] Serialize_unique_strings( Dictionary<string,object> dict) { return dict.Keys.ToArray(); } With these three additional functions Main() now looks like this:static void Main(string[] args) { var input = Accept_string_list(args); var strings = Parse_string_list(input); var dict = Compile_unique_strings(strings); var output = Serialize_unique_strings(dict); Present_deduplicated_string_list(output); } I think that´s very understandable code: just read it from top to bottom and you know how the solution to the problem works. It´s a mirror image of the initial design: Accept string list from command line Parse the input string into a true list of strings. Register each string in a dictionary/map/set. That way duplicates get cast away. Transform the data structure into a list of unique strings. Present de-duplicated strings on standard output You can even re-generate the design by just looking at the code. Code and functional design thus are always in sync - if you follow some simple rules. But about that later. And as a bonus: all the functions making up the process are small - which means easy to understand, too. So much for an initial concrete example. Now it´s time for some theory. Because there is method to this madness ;-) The above has only scratched the surface. Introducing Flow Design Functional design starts with a given function, the Entry Point. Its goal is to describe the behavior of the program when the Entry Point is triggered using a process, not an algorithm. An algorithm consists of logic, a process on the other hand consists just of steps or stages. Each processing step transforms input into output or a side effect. Also it might access resources, e.g. a printer, a database, or just memory. Processing steps thus can rely on state of some sort. This is different from Functional Programming, where functions are supposed to not be stateful and not cause side effects.[1] In its simplest form a process can be written as a bullet point list of steps, e.g. Get data from user Output result to user Transform data Parse data Map result for output Such a compilation of steps - possibly on different levels of abstraction - often is the first artifact of functional design. It can be generated by a team in an initial design brainstorming. Next comes ordering the steps. What should happen first, what next etc.? Get data from user Parse data Transform data Map result for output Output result to user That´s great for a start into functional design. It´s better than starting to code right away on a given function using TDD. Please get me right: TDD is a valuable practice. But it can be unnecessarily hard if the scope of a functionn is too large. But how do you know beforehand without investing some thinking? And how to do this thinking in a systematic fashion? My recommendation: For any given function you´re supposed to implement first do a functional design. Then, once you´re confident you know the processing steps - which are pretty small - refine and code them using TDD. You´ll see that´s much, much easier - and leads to cleaner code right away. For more information on this approach I call “Informed TDD” read my book of the same title. Thinking before coding is smart. And writing down the solution as a bunch of functions possibly is the simplest thing you can do, I´d say. It´s more according to the KISS (Keep It Simple, Stupid) principle than returning constants or other trivial stuff TDD development often is started with. So far so good. A simple ordered list of processing steps will do to start with functional design. As shown in the above example such steps can easily be translated into functions. Moving from design to coding thus is simple. However, such a list does not scale. Processing is not always that simple to be captured in a list. And then the list is just text. Again. Like code. That means the design is lacking visuality. Textual representations need more parsing by your brain than visual representations. Plus they are limited in their “dimensionality”: text just has one dimension, it´s sequential. Alternatives and parallelism are hard to encode in text. In addition the functional design using numbered lists lacks data. It´s not visible what´s the input, output, and state of the processing steps. That´s why functional design should be done using a lightweight visual notation. No tool is necessary to draw such designs. Use pen and paper; a flipchart, a whiteboard, or even a napkin is sufficient. Visualizing processes The building block of the functional design notation is a functional unit. I mostly draw it like this: Something is done, it´s clear what goes in, it´s clear what comes out, and it´s clear what the processing step requires in terms of state or hardware. Whenever input flows into a functional unit it gets processed and output is produced and/or a side effect occurs. Flowing data is the driver of something happening. That´s why I call this approach to functional design Flow Design. It´s about data flow instead of control flow. Control flow like in algorithms is of no concern to functional design. Thinking about control flow simply is too low level. Once you start with control flow you easily get bogged down by tons of details. That´s what you want to avoid during design. Design is supposed to be quick, broad brush, abstract. It should give overview. But what about all the details? As Robert C. Martin rightly said: “Programming is abot detail”. Detail is a matter of code. Once you start coding the processing steps you designed you can worry about all the detail you want. Functional design does not eliminate all the nitty gritty. It just postpones tackling them. To me that´s also an example of the SRP. Function design has the responsibility to come up with a solution to a problem posed by a single function (Entry Point). And later coding has the responsibility to implement the solution down to the last detail (i.e. statement, API-call). TDD unfortunately mixes both responsibilities. It´s just coding - and thereby trying to find detailed implementations (green phase) plus getting the design right (refactoring). To me that´s one reason why TDD has failed to deliver on its promise for many developers. Using functional units as building blocks of functional design processes can be depicted very easily. Here´s the initial process for the example problem: For each processing step draw a functional unit and label it. Choose a verb or an “action phrase” as a label, not a noun. Functional design is about activities, not state or structure. Then make the output of an upstream step the input of a downstream step. Finally think about the data that should flow between the functional units. Write the data above the arrows connecting the functional units in the direction of the data flow. Enclose the data description in brackets. That way you can clearly see if all flows have already been specified. Empty brackets mean “no data is flowing”, but nevertheless a signal is sent. A name like “list” or “strings” in brackets describes the data content. Use lower case labels for that purpose. A name starting with an upper case letter like “String” or “Customer” on the other hand signifies a data type. If you like, you also can combine descriptions with data types by separating them with a colon, e.g. (list:string) or (strings:string[]). But these are just suggestions from my practice with Flow Design. You can do it differently, if you like. Just be sure to be consistent. Flows wired-up in this manner I call one-dimensional (1D). Each functional unit just has one input and/or one output. A functional unit without an output is possible. It´s like a black hole sucking up input without producing any output. Instead it produces side effects. A functional unit without an input, though, does make much sense. When should it start to work? What´s the trigger? That´s why in the above process even the first processing step has an input. If you like, view such 1D-flows as pipelines. Data is flowing through them from left to right. But as you can see, it´s not always the same data. It get´s transformed along its passage: (args) becomes a (list) which is turned into (strings). The Principle of Mutual Oblivion A very characteristic trait of flows put together from function units is: no functional units knows another one. They are all completely independent of each other. Functional units don´t know where their input is coming from (or even when it´s gonna arrive). They just specify a range of values they can process. And they promise a certain behavior upon input arriving. Also they don´t know where their output is going. They just produce it in their own time independent of other functional units. That means at least conceptually all functional units work in parallel. Functional units don´t know their “deployment context”. They now nothing about the overall flow they are place in. They are just consuming input from some upstream, and producing output for some downstream. That makes functional units very easy to test. At least as long as they don´t depend on state or resources. I call this the Principle of Mutual Oblivion (PoMO). Functional units are oblivious of others as well as an overall context/purpose. They are just parts of a whole focused on a single responsibility. How the whole is built, how a larger goal is achieved, is of no concern to the single functional units. By building software in such a manner, functional design interestingly follows nature. Nature´s building blocks for organisms also follow the PoMO. The cells forming your body do not know each other. Take a nerve cell “controlling” a muscle cell for example:[2] The nerve cell does not know anything about muscle cells, let alone the specific muscel cell it is “attached to”. Likewise the muscle cell does not know anything about nerve cells, let a lone a specific nerve cell “attached to” it. Saying “the nerve cell is controlling the muscle cell” thus only makes sense when viewing both from the outside. “Control” is a concept of the whole, not of its parts. Control is created by wiring-up parts in a certain way. Both cells are mutually oblivious. Both just follow a contract. One produces Acetylcholine (ACh) as output, the other consumes ACh as input. Where the ACh is going, where it´s coming from neither cell cares about. Million years of evolution have led to this kind of division of labor. And million years of evolution have produced organism designs (DNA) which lead to the production of these different cell types (and many others) and also to their co-location. The result: the overall behavior of an organism. How and why this happened in nature is a mystery. For our software, though, it´s clear: functional and quality requirements needs to be fulfilled. So we as developers have to become “intelligent designers” of “software cells” which we put together to form a “software organism” which responds in satisfying ways to triggers from it´s environment. My bet is: If nature gets complex organisms working by following the PoMO, who are we to not apply this recipe for success to our much simpler “machines”? So my rule is: Wherever there is functionality to be delivered, because there is a clear Entry Point into software, design the functionality like nature would do it. Build it from mutually oblivious functional units. That´s what Flow Design is about. In that way it´s even universal, I´d say. Its notation can also be applied to biology: Never mind labeling the functional units with nouns. That´s ok in Flow Design. You´ll do that occassionally for functional units on a higher level of abstraction or when their purpose is close to hardware. Getting a cockroach to roam your bedroom takes 1,000,000 nerve cells (neurons). Getting the de-duplication program to do its job just takes 5 “software cells” (functional units). Both, though, follow the same basic principle. Translating functional units into code Moving from functional design to code is no rocket science. In fact it´s straightforward. There are two simple rules: Translate an input port to a function. Translate an output port either to a return statement in that function or to a function pointer visible to that function. The simplest translation of a functional unit is a function. That´s what you saw in the above example. Functions are mutually oblivious. That why Functional Programming likes them so much. It makes them composable. Which is the reason, nature works according to the PoMO. Let´s be clear about one thing: There is no dependency injection in nature. For all of an organism´s complexity no DI container is used. Behavior is the result of smooth cooperation between mutually oblivious building blocks. Functions will often be the adequate translation for the functional units in your designs. But not always. Take for example the case, where a processing step should not always produce an output. Maybe the purpose is to filter input. Here the functional unit consumes words and produces words. But it does not pass along every word flowing in. Some words are swallowed. Think of a spell checker. It probably should not check acronyms for correctness. There are too many of them. Or words with no more than two letters. Such words are called “stop words”. In the above picture the optionality of the output is signified by the astrisk outside the brackets. It means: Any number of (word) data items can flow from the functional unit for each input data item. It might be none or one or even more. This I call a stream of data. Such behavior cannot be translated into a function where output is generated with return. Because a function always needs to return a value. So the output port is translated into a function pointer or continuation which gets passed to the subroutine when called:[3]void filter_stop_words( string word, Action<string> onNoStopWord) { if (...check if not a stop word...) onNoStopWord(word); } If you want to be nitpicky you might call such a function pointer parameter an injection. And technically you´re right. Conceptually, though, it´s not an injection. Because the subroutine is not functionally dependent on the continuation. Firstly continuations are procedures, i.e. subroutines without a return type. Remember: Flow Design is about unidirectional data flow. Secondly the name of the formal parameter is chosen in a way as to not assume anything about downstream processing steps. onNoStopWord describes a situation (or event) within the functional unit only. Translating output ports into function pointers helps keeping functional units mutually oblivious in cases where output is optional or produced asynchronically. Either pass the function pointer to the function upon call. Or make it global by putting it on the encompassing class. Then it´s called an event. In C# that´s even an explicit feature.class Filter { public void filter_stop_words( string word) { if (...check if not a stop word...) onNoStopWord(word); } public event Action<string> onNoStopWord; } When to use a continuation and when to use an event dependens on how a functional unit is used in flows and how it´s packed together with others into classes. You´ll see examples further down the Flow Design road. Another example of 1D functional design Let´s see Flow Design once more in action using the visual notation. How about the famous word wrap kata? Robert C. Martin has posted a much cited solution including an extensive reasoning behind his TDD approach. So maybe you want to compare it to Flow Design. The function signature given is:string WordWrap(string text, int maxLineLength) {...} That´s not an Entry Point since we don´t see an application with an environment and users. Nevertheless it´s a function which is supposed to provide a certain functionality. The text passed in has to be reformatted. The input is a single line of arbitrary length consisting of words separated by spaces. The output should consist of one or more lines of a maximum length specified. If a word is longer than a the maximum line length it can be split in multiple parts each fitting in a line. Flow Design Let´s start by brainstorming the process to accomplish the feat of reformatting the text. What´s needed? Words need to be assembled into lines Words need to be extracted from the input text The resulting lines need to be assembled into the output text Words too long to fit in a line need to be split Does sound about right? I guess so. And it shows a kind of priority. Long words are a special case. So maybe there is a hint for an incremental design here. First let´s tackle “average words” (words not longer than a line). Here´s the Flow Design for this increment: The the first three bullet points turned into functional units with explicit data added. As the signature requires a text is transformed into another text. See the input of the first functional unit and the output of the last functional unit. In between no text flows, but words and lines. That´s good to see because thereby the domain is clearly represented in the design. The requirements are talking about words and lines and here they are. But note the asterisk! It´s not outside the brackets but inside. That means it´s not a stream of words or lines, but lists or sequences. For each text a sequence of words is output. For each sequence of words a sequence of lines is produced. The asterisk is used to abstract from the concrete implementation. Like with streams. Whether the list of words gets implemented as an array or an IEnumerable is not important during design. It´s an implementation detail. Does any processing step require further refinement? I don´t think so. They all look pretty “atomic” to me. And if not… I can always backtrack and refine a process step using functional design later once I´ve gained more insight into a sub-problem. Implementation The implementation is straightforward as you can imagine. The processing steps can all be translated into functions. Each can be tested easily and separately. Each has a focused responsibility. And the process flow becomes just a sequence of function calls: Easy to understand. It clearly states how word wrapping works - on a high level of abstraction. And it´s easy to evolve as you´ll see. Flow Design - Increment 2 So far only texts consisting of “average words” are wrapped correctly. Words not fitting in a line will result in lines too long. Wrapping long words is a feature of the requested functionality. Whether it´s there or not makes a difference to the user. To quickly get feedback I decided to first implement a solution without this feature. But now it´s time to add it to deliver the full scope. Fortunately Flow Design automatically leads to code following the Open Closed Principle (OCP). It´s easy to extend it - instead of changing well tested code. How´s that possible? Flow Design allows for extension of functionality by inserting functional units into the flow. That way existing functional units need not be changed. The data flow arrow between functional units is a natural extension point. No need to resort to the Strategy Pattern. No need to think ahead where extions might need to be made in the future. I just “phase in” the remaining processing step: Since neither Extract words nor Reformat know of their environment neither needs to be touched due to the “detour”. The new processing step accepts the output of the existing upstream step and produces data compatible with the existing downstream step. Implementation - Increment 2 A trivial implementation checking the assumption if this works does not do anything to split long words. The input is just passed on: Note how clean WordWrap() stays. The solution is easy to understand. A developer looking at this code sometime in the future, when a new feature needs to be build in, quickly sees how long words are dealt with. Compare this to Robert C. Martin´s solution:[4] How does this solution handle long words? Long words are not even part of the domain language present in the code. At least I need considerable time to understand the approach. Admittedly the Flow Design solution with the full implementation of long word splitting is longer than Robert C. Martin´s. At least it seems. Because his solution does not cover all the “word wrap situations” the Flow Design solution handles. Some lines would need to be added to be on par, I guess. But even then… Is a difference in LOC that important as long as it´s in the same ball park? I value understandability and openness for extension higher than saving on the last line of code. Simplicity is not just less code, it´s also clarity in design. But don´t take my word for it. Try Flow Design on larger problems and compare for yourself. What´s the easier, more straightforward way to clean code? And keep in mind: You ain´t seen all yet ;-) There´s more to Flow Design than described in this chapter. In closing I hope I was able to give you a impression of functional design that makes you hungry for more. To me it´s an inevitable step in software development. Jumping from requirements to code does not scale. And it leads to dirty code all to quickly. Some thought should be invested first. Where there is a clear Entry Point visible, it´s functionality should be designed using data flows. Because with data flows abstraction is possible. For more background on why that´s necessary read my blog article here. For now let me point out to you - if you haven´t already noticed - that Flow Design is a general purpose declarative language. It´s “programming by intention” (Shalloway et al.). Just write down how you think the solution should work on a high level of abstraction. This breaks down a large problem in smaller problems. And by following the PoMO the solutions to those smaller problems are independent of each other. So they are easy to test. Or you could even think about getting them implemented in parallel by different team members. Flow Design not only increases evolvability, but also helps becoming more productive. All team members can participate in functional design. This goes beyon collective code ownership. We´re talking collective design/architecture ownership. Because with Flow Design there is a common visual language to talk about functional design - which is the foundation for all other design activities.   PS: If you like what you read, consider getting my ebook “The Incremental Architekt´s Napkin”. It´s where I compile all the articles in this series for easier reading. I like the strictness of Function Programming - but I also find it quite hard to live by. And it certainly is not what millions of programmers are used to. Also to me it seems, the real world is full of state and side effects. So why give them such a bad image? That´s why functional design takes a more pragmatic approach. State and side effects are ok for processing steps - but be sure to follow the SRP. Don´t put too much of it into a single processing step. ? Image taken from www.physioweb.org ? My code samples are written in C#. C# sports typed function pointers called delegates. Action is such a function pointer type matching functions with signature void someName(T t). Other languages provide similar ways to work with functions as first class citizens - even Java now in version 8. I trust you find a way to map this detail of my translation to your favorite programming language. I know it works for Java, C++, Ruby, JavaScript, Python, Go. And if you´re using a Functional Programming language it´s of course a no brainer. ? Taken from his blog post “The Craftsman 62, The Dark Path”. ?

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  • Class-Level Model Validation with EF Code First and ASP.NET MVC 3

    - by ScottGu
    Earlier this week the data team released the CTP5 build of the new Entity Framework Code-First library.  In my blog post a few days ago I talked about a few of the improvements introduced with the new CTP5 build.  Automatic support for enforcing DataAnnotation validation attributes on models was one of the improvements I discussed.  It provides a pretty easy way to enable property-level validation logic within your model layer. You can apply validation attributes like [Required], [Range], and [RegularExpression] – all of which are built-into .NET 4 – to your model classes in order to enforce that the model properties are valid before they are persisted to a database.  You can also create your own custom validation attributes (like this cool [CreditCard] validator) and have them be automatically enforced by EF Code First as well.  This provides a really easy way to validate property values on your models.  I showed some code samples of this in action in my previous post. Class-Level Model Validation using IValidatableObject DataAnnotation attributes provides an easy way to validate individual property values on your model classes.  Several people have asked - “Does EF Code First also support a way to implement class-level validation methods on model objects, for validation rules than need to span multiple property values?”  It does – and one easy way you can enable this is by implementing the IValidatableObject interface on your model classes. IValidatableObject.Validate() Method Below is an example of using the IValidatableObject interface (which is built-into .NET 4 within the System.ComponentModel.DataAnnotations namespace) to implement two custom validation rules on a Product model class.  The two rules ensure that: New units can’t be ordered if the Product is in a discontinued state New units can’t be ordered if there are already more than 100 units in stock We will enforce these business rules by implementing the IValidatableObject interface on our Product class, and by implementing its Validate() method like so: The IValidatableObject.Validate() method can apply validation rules that span across multiple properties, and can yield back multiple validation errors. Each ValidationResult returned can supply both an error message as well as an optional list of property names that caused the violation (which is useful when displaying error messages within UI). Automatic Validation Enforcement EF Code-First (starting with CTP5) now automatically invokes the Validate() method when a model object that implements the IValidatableObject interface is saved.  You do not need to write any code to cause this to happen – this support is now enabled by default. This new support means that the below code – which violates one of our above business rules – will automatically throw an exception (and abort the transaction) when we call the “SaveChanges()” method on our Northwind DbContext: In addition to reactively handling validation exceptions, EF Code First also allows you to proactively check for validation errors.  Starting with CTP5, you can call the “GetValidationErrors()” method on the DbContext base class to retrieve a list of validation errors within the model objects you are working with.  GetValidationErrors() will return a list of all validation errors – regardless of whether they are generated via DataAnnotation attributes or by an IValidatableObject.Validate() implementation.  Below is an example of proactively using the GetValidationErrors() method to check (and handle) errors before trying to call SaveChanges(): ASP.NET MVC 3 and IValidatableObject ASP.NET MVC 2 included support for automatically honoring and enforcing DataAnnotation attributes on model objects that are used with ASP.NET MVC’s model binding infrastructure.  ASP.NET MVC 3 goes further and also honors the IValidatableObject interface.  This combined support for model validation makes it easy to display appropriate error messages within forms when validation errors occur.  To see this in action, let’s consider a simple Create form that allows users to create a new Product: We can implement the above Create functionality using a ProductsController class that has two “Create” action methods like below: The first Create() method implements a version of the /Products/Create URL that handles HTTP-GET requests - and displays the HTML form to fill-out.  The second Create() method implements a version of the /Products/Create URL that handles HTTP-POST requests - and which takes the posted form data, ensures that is is valid, and if it is valid saves it in the database.  If there are validation issues it redisplays the form with the posted values.  The razor view template of our “Create” view (which renders the form) looks like below: One of the nice things about the above Controller + View implementation is that we did not write any validation logic within it.  The validation logic and business rules are instead implemented entirely within our model layer, and the ProductsController simply checks whether it is valid (by calling the ModelState.IsValid helper method) to determine whether to try and save the changes or redisplay the form with errors. The Html.ValidationMessageFor() helper method calls within our view simply display the error messages our Product model’s DataAnnotations and IValidatableObject.Validate() method returned.  We can see the above scenario in action by filling out invalid data within the form and attempting to submit it: Notice above how when we hit the “Create” button we got an error message.  This was because we ticked the “Discontinued” checkbox while also entering a value for the UnitsOnOrder (and so violated one of our business rules).  You might ask – how did ASP.NET MVC know to highlight and display the error message next to the UnitsOnOrder textbox?  It did this because ASP.NET MVC 3 now honors the IValidatableObject interface when performing model binding, and will retrieve the error messages from validation failures with it. The business rule within our Product model class indicated that the “UnitsOnOrder” property should be highlighted when the business rule we hit was violated: Our Html.ValidationMessageFor() helper method knew to display the business rule error message (next to the UnitsOnOrder edit box) because of the above property name hint we supplied: Keeping things DRY ASP.NET MVC and EF Code First enables you to keep your validation and business rules in one place (within your model layer), and avoid having it creep into your Controllers and Views.  Keeping the validation logic in the model layer helps ensure that you do not duplicate validation/business logic as you add more Controllers and Views to your application.  It allows you to quickly change your business rules/validation logic in one single place (within your model layer) – and have all controllers/views across your application immediately reflect it.  This help keep your application code clean and easily maintainable, and makes it much easier to evolve and update your application in the future. Summary EF Code First (starting with CTP5) now has built-in support for both DataAnnotations and the IValidatableObject interface.  This allows you to easily add validation and business rules to your models, and have EF automatically ensure that they are enforced anytime someone tries to persist changes of them to a database.  ASP.NET MVC 3 also now supports both DataAnnotations and IValidatableObject as well, which makes it even easier to use them with your EF Code First model layer – and then have the controllers/views within your web layer automatically honor and support them as well.  This makes it easy to build clean and highly maintainable applications. You don’t have to use DataAnnotations or IValidatableObject to perform your validation/business logic.  You can always roll your own custom validation architecture and/or use other more advanced validation frameworks/patterns if you want.  But for a lot of applications this built-in support will probably be sufficient – and provide a highly productive way to build solutions. Hope this helps, Scott P.S. In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu

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  • Tool to identify Internet Explorer rendering differences with css

    - by Bakaburg
    I develop website using chrome and mac os as development environment. Since my audience is pretty specific I don't feel the necessity for too much backward compatibility with IE8 and less. However to my great dismay, even IE9 looks totally broken... I would like to know if there's on the web a tool that could tell me what probably went wrong with IE, that is a webapp that parse the rendered css and check which rules are probably totally broken in IE9.

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  • Compared to Firefox 4 and Google Chrome 10, what can't IE9 do?

    - by ClosureCowboy
    If a website works in Firefox 4 and in Google Chrome 10, what could potentially cause that website not to work (broken layout or broken JavaScript) in IE9? What limitations and differences does IE9 have, aside from vendor-specific stylesheet rules? Yes, that is a painfully vague question — that's because I am not asking this question from the perspective of someone with a specific problem! I'm asking this question from the perspective of someone with a working website who does not have access to IE9.

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  • /usr/bin/python (Python 2.4) was deleted on CentOS 5. I compiled from source but yum is still broken. How can I get everything back to the way it was?

    - by Maxwell
    I saw a lot of other questions like this but none of them answered the exact part I am having trouble with (actually installing the Python RPM). Someone on my system deleted /usr/bin/python and /usr/bin/python2.4 on my 64 bit CentOS 5.8 installation. I recompiled Python 2.4 from source, but now whenever I try to yum install anything I get the following error: [root@cerulean-OW1 ~]# yum install httpd There was a problem importing one of the Python modules required to run yum. The error leading to this problem was: No module named yum Please install a package which provides this module, or verify that the module is installed correctly. It's possible that the above module doesn't match the current version of Python, which is: 2.4 (#1, Dec 16 2012, 09:16:56) [GCC 4.1.2 20080704 (Red Hat 4.1.2-52)] If you cannot solve this problem yourself, please go to the yum faq at: http://wiki.linux.duke.edu/YumFaq I checked http://wiki.linux.duke.edu/YumFaq and it said the following: If you are getting a message that yum itself is the missing module then you probably installed it incorreclty (or installed the source rpm using make/make install). If possible, find a prebuilt rpm that will work for your system like one from Fedora or CentOS. Or, you can download the srpm and do a rpmbuild --rebuild yum*.src.rpm I tried going to http://rpm.pbone.net/index.php3/stat/4/idpl/17838875/dir/centos_5/com/python-2.4.3-46.el5.x86_64.rpm.html to install Python, which resulted in the following error: [root@cerulean-OW1 ~]# rpm -Uvh python-2.4.3-46.el5.x86_64.rpm error: Failed dependencies: python-libs-x86_64 = 2.4.3-46.el5 is needed by python-2.4.3-46.el5.x86_64 So I tried installing python-libs-x86_64, which resulted in the following: [root@cerulean-OW1 ~]# rpm -Uvh python-libs-2.4.3-46.el5_8.2.x86_64.rpm warning: python-libs-2.4.3-46.el5_8.2.x86_64.rpm: Header V3 DSA signature: NOKEY, key ID 192a7d7d Preparing... ########################################### [100%] package python-libs-2.4.3-46.el5_8.2.x86_64 is already installed file /usr/lib64/libpython2.4.so.1.0 from install of python-libs-2.4.3-46.el5_8.2.x86_64 conflicts with file from package python-libs-2.4.3-46.el5_8.2.x86_64

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  • Reproducible file corruption for files on windows share

    - by bbuser
    We have about 40 file servers in our intranet to distribute software packages. The servers have names like example01, example02 etc. Every name resolves to a single IP-address (A-record) and the IP resolves back to that name (PTR) for every single server. The thing is, that for a certain file (mypackage.cab) I get different results depending on whether I use: \\192.0.2.01\fs\pkg\X12345678 or \\example01.foo\fs\pkg\X12345678 While in one case the file is correct in the other case the file has exactly the right size, but it is all zeros. For a certain combination of client and server I can reproduce this reliably. It doesn´t matter if I download in Windows Explorer, via robocopy or even from Linux with smbclient. It´s always the same, one file corrupt, the other ok. It happens only for certain combinations of clients and servers, not others. For example: client01 example01.foo -> OK (192.0.2.01 is also OK) client01 example02.foo -> broken (but 192.0.2.02 is OK) client02 example01.foo -> broken (but 192.0.2.01 is OK) client02 example02.foo -> OK (192.0.2.02 is also OK) client03 example06.foo -> OK (but 192.0.2.06 is broken) client03 example07.foo -> OK (192.0.2.07 is also OK) etc... In some cases I get the broken file when I use the IP address in other cases when I use the name. For every client the majority of servers is Ok, but from every client I tested I have at least 4 cases of broken files. All this happens only for mypackage.cab (about 5k in size), it never happened for any of the other files in the same directory. Confused? Certainly I am. Any idea what can cause this or any idea what to try to figure it out is welcome. Clients are Windows XP. Servers are NetApp filers I don´t have access to. I can (and will) contact the filer team again, but first I have to have an idea what is going on.

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