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  • Fluent NHibernate Automapping with RIA services

    - by VexXtreme
    Hi guys I've encountered a slight problem recently, or rather a lack of understanding of how NHibernate automapping works with RIA data services. Namely, I don't understand how to use Association and Include attributes. For instance, I've created two tables in my database and corresponding classes (that NHibernate correctly fills). The problem is, RIA doesn't generate properties (collections) bound by foreign key to other tables, on the client side, although I've defined them in my classes in my domain model... it generates just properties that belong to their own class, on the client side. I assume that these attributes aren't necessary since NHibernate automapper is supposed to fill those collections on it's own... I'm quite confused as to how this works. And I don't understand why RIA simply skips properties such as public virtual IList<Medication> Medications{ get; set; } during autogeneration. Any input is appreciated Thanks

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  • Silverlight RelativeSource of TemplatedParent Binding within a DataTemplate, Is it possible?

    - by Matt.M
    I'm trying to make a bar graph Usercontrol. I'm creating each bar using a DataTemplate. The problem is in order to compute the height of each bar, I first need to know the height of its container (the TemplatedParent). Unfortunately what I have: Height="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=Height, Converter={StaticResource HeightConverter}, Mode=OneWay}" Does not work. Each time a value of NaN is returned to my Converter. Does RelativeSource={RelativeSource TemplatedParent} not work in this context? What else can I do to allow my DataTemplate to "talk" to the element it is being applied to? Incase it helps here is the barebones DataTemplate: <DataTemplate x:Key="BarGraphTemplate"> <Grid Width="30"> <Rectangle HorizontalAlignment="Center" Stroke="Black" Width="20" Height="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=Height, Converter={StaticResource HeightConverter}, Mode=OneWay}" VerticalAlignment="Bottom" /> </Grid> </DataTemplate>

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  • Silverlight 4 MediaElement play sound

    - by NealWalters
    I converted a local sound file to a resource, which built this in my XAML: <UserControl.Resources> <my:Uri x:Key="SoundFiles">file:///c:/Audio/HebrewDemo/Shalom.wav</my:Uri> </UserControl.Resources> I did this by pasting a local disk mp3 filename into source, then clicked on the "dot" by source and chose "Extract Value to Resource". When I run, it tells me that "Uri" is not valid, and sure enough, in the Intellisense, I see other elements that start with "uri" but not just URI by itself. In the real world I want to specify a dynamic mp3 file name. For example, I might have a database of foreign language words used for flashcards, I want to play a sound file on a URL. But I thought I would try to walk before running...

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  • Ops Center 12c - Provisioning Solaris Using a Card-Based NIC

    - by scottdickson
    It's been a long time since last I added something here, but having some conversations this last week, I got inspired to update things. I've been spending a lot of time with Ops Center for managing and installing systems these days.  So, I suspect a number of my upcoming posts will be in that area. Today, I want to look at how to provision Solaris using Ops Center when your network is not connected to one of the built-in NICs.  We'll talk about how this can work for both Solaris 10 and Solaris 11, since they are pretty similar.  In both cases, WANboot is a key piece of the story. Here's what I want to do:  I have a Sun Fire T2000 server with a Quad-GbE nxge card installed.  The only network is connected to port 2 on that card rather than the built-in network interfaces.  I want to install Solaris on it across the network, either Solaris 10 or Solaris 11.  I have met with a lot of customers lately who have a similar architecture.  Usually, they have T4-4 servers with the network connected via 10GbE connections. Add to this mix the fact that I use Ops Center to manage the systems in my lab, so I really would like to add this to Ops Center.  If possible, I would like this to be completely hands free.  I can't quite do that yet. Close, but not quite. WANBoot or Old-Style NetBoot? When a system is installed from the network, it needs some help getting the process rolling.  It has to figure out what its network configuration (IP address, gateway, etc.) ought to be.  It needs to figure out what server is going to help it boot and install, and it needs the instructions for the installation.  There are two different ways to bootstrap an installation of Solaris on SPARC across the network.   The old way uses a broadcast of RARP or more recently DHCP to obtain the IP configuration and the rest of the information needed.  The second is to explicitly configure this information in the OBP and use WANBoot for installation WANBoot has a number of benefits over broadcast-based installation: it is not restricted to a single subnet; it does not require special DHCP configuration or DHCP helpers; it uses standard HTTP and HTTPS protocols which traverse firewalls much more easily than NFS-based package installation.  But, WANBoot is not available on really old hardware and WANBoot requires the use o Flash Archives in Solaris 10.  Still, for many people, this is a great approach. As it turns out, WANBoot is necessary if you plan to install using a NIC on a card rather than a built-in NIC. Identifying Which Network Interface to Use One of the trickiest aspects to this process, and the one that actually requires manual intervention to set up, is identifying how the OBP and Solaris refer to the NIC that we want to use to boot.  The OBP already has device aliases configured for the built-in NICs called net, net0, net1, net2, net3.  The device alias net typically points to net0 so that when you issue the command  "boot net -v install", it uses net0 for the boot.  Our task is to figure out the network instance for the NIC we want to use.  We will need to get to the OBP console of the system we want to install in order to figure out what the network should be called.  I will presume you know how to get to the ok prompt.  Once there, we have to see what networks the OBP sees and identify which one is associated with our NIC using the OBP command show-nets. SunOS Release 5.11 Version 11.0 64-bit Copyright (c) 1983, 2011, Oracle and/or its affiliates. All rights reserved. {4} ok banner Sun Fire T200, No Keyboard Copyright (c) 1998, 2010, Oracle and/or its affiliates. All rights reserved. OpenBoot 4.30.4.b, 32640 MB memory available, Serial #69057548. Ethernet address 0:14:4f:1d:bc:c, Host ID: 841dbc0c. {4} ok show-nets a) /pci@7c0/pci@0/pci@2/network@0,1 b) /pci@7c0/pci@0/pci@2/network@0 c) /pci@780/pci@0/pci@8/network@0,3 d) /pci@780/pci@0/pci@8/network@0,2 e) /pci@780/pci@0/pci@8/network@0,1 f) /pci@780/pci@0/pci@8/network@0 g) /pci@780/pci@0/pci@1/network@0,1 h) /pci@780/pci@0/pci@1/network@0 q) NO SELECTION Enter Selection, q to quit: d /pci@780/pci@0/pci@8/network@0,2 has been selected. Type ^Y ( Control-Y ) to insert it in the command line. e.g. ok nvalias mydev ^Y for creating devalias mydev for /pci@780/pci@0/pci@8/network@0,2 {4} ok devalias ... net3 /pci@7c0/pci@0/pci@2/network@0,1 net2 /pci@7c0/pci@0/pci@2/network@0 net1 /pci@780/pci@0/pci@1/network@0,1 net0 /pci@780/pci@0/pci@1/network@0 net /pci@780/pci@0/pci@1/network@0 ... name aliases By looking at the devalias and the show-nets output, we can see that our Quad-GbE card must be the device nodes starting with  /pci@780/pci@0/pci@8/network@0.  The cable for our network is plugged into the 3rd slot, so the device address for our network must be /pci@780/pci@0/pci@8/network@0,2. With that, we can create a device alias for our network interface.  Naming the device alias may take a little bit of trial and error, especially in Solaris 11 where the device alias seems to matter more with the new virtualized network stack. So far in my testing, since this is the "next" network interface to be used, I have found success in naming it net4, even though it's a NIC in the middle of a card that might, by rights, be called net6 (assuming the 0th interface on the card is the next interface identified by Solaris and this is the 3rd interface on the card).  So, we will call it net4.  We need to assign a device alias to it: {4} ok nvalias net4 /pci@780/pci@0/pci@8/network@0,2 {4} ok devalias net4 /pci@780/pci@0/pci@8/network@0,2 ... We also may need to have the MAC for this particular interface, so let's get it, too.  To do this, we go to the device and interrogate its properties. {4} ok cd /pci@780/pci@0/pci@8/network@0,2 {4} ok .properties assigned-addresses 82060210 00000000 03000000 00000000 01000000 82060218 00000000 00320000 00000000 00008000 82060220 00000000 00328000 00000000 00008000 82060230 00000000 00600000 00000000 00100000 local-mac-address 00 21 28 20 42 92 phy-type mif ... From this, we can see that the MAC for this interface is  00:21:28:20:42:92.  We will need this later. This is all we need to do at the OBP.  Now, we can configure Ops Center to use this interface. Network Boot in Solaris 10 Solaris 10 turns out to be a little simpler than Solaris 11 for this sort of a network boot.  Since WANBoot in Solaris 10 fetches a specified In order to install the system using Ops Center, it is necessary to create a OS Provisioning profile and its corresponding plan.  I am going to presume that you already know how to do this within Ops Center 12c and I will just cover the differences between a regular profile and a profile that can use an alternate interface. Create a OS Provisioning profile for Solaris 10 as usual.  However, when you specify the network resources for the primary network, click on the name of the NIC, probably GB_0, and rename it to GB_N/netN, where N is the instance number you used previously in creating the device alias.  This is where the trial and error may come into play.  You may need to try a few instance numbers before you, the OBP, and Solaris all agree on the instance number.  Mark this as the boot network. For Solaris 10, you ought to be able to then apply the OS Provisioning profile to the server and it should install using that interface.  And if you put your cards in the same slots and plug the networks into the same NICs, this profile is reusable across multiple servers. Why This Works If you watch the console as Solaris boots during the OSP process, Ops Center is going to look for the device alias netN.  Since WANBoot requires a device alias called just net, Ops Center uses the value of your netN device alias and assigns that device to the net alias.  That means that boot net will automatically use this device.  Very cool!  Here's a trace from the console as Ops Center provisions a server: Sun Sun Fire T200, No KeyboardCopyright (c) 1998, 2010, Oracle and/or its affiliates. All rights reserved.OpenBoot 4.30.4.b, 32640 MB memory available, Serial #69057548.Ethernet address 0:14:4f:1d:bc:c, Host ID: 841dbc0c.auto-boot? =            false{0} ok  {0} ok printenv network-boot-argumentsnetwork-boot-arguments =  host-ip=10.140.204.234,router-ip=10.140.204.1,subnet-mask=255.255.254.0,hostname=atl-sewr-52,client-id=0100144F1DBC0C,file=http://10.140.204.22:5555/cgi-bin/wanboot-cgi{0} ok {0} ok devalias net net                      /pci@780/pci@0/pci@1/network@0{0} ok devalias net4 net4                     /pci@780/pci@0/pci@8/network@0,2{0} ok devalias net /pci@780/pci@0/pci@8/network@0,2{0} ok setenv network-boot-arguments host-ip=10.140.204.234,router-ip=10.140.204.1,subnet-mask=255.255.254.0,hostname=atl-sewr-52,client-id=0100144F1DBC0C,file=http://10.140.204.22:8004/cgi-bin/wanboot-cginetwork-boot-arguments =  host-ip=10.140.204.234,router-ip=10.140.204.1,subnet-mask=255.255.254.0,hostname=atl-sewr-52,client-id=0100144F1DBC0C,file=http://10.140.204.22:8004/cgi-bin/wanboot-cgi{0} ok {0} ok boot net - installBoot device: /pci@780/pci@0/pci@8/network@0,2  File and args: - install/pci@780/pci@0/pci@8/network@0,2: 1000 Mbps link up<time unavailable> wanboot info: WAN boot messages->console<time unavailable> wanboot info: configuring /pci@780/pci@0/pci@8/network@0,2 See what happened?  Ops Center looked for the network device alias called net4 that we specified in the profile, took the value from it, and made it the net device alias for the boot.  Pretty cool! WANBoot and Solaris 11 Solaris 11 requires an additional step since the Automated Installer in Solaris 11 uses the MAC address of the network to figure out which manifest to use for system installation.  In order to make sure this is available, we have to take an extra step to associate the MAC of the NIC on the card with the host.  So, in addition to creating the device alias like we did above, we also have to declare to Ops Center that the host has this new MAC. Declaring the NIC Start out by discovering the hardware as usual.  Once you have discovered it, take a look under the Connectivity tab to see what networks it has discovered.  In the case of this system, it shows the 4 built-in networks, but not the networks on the additional cards.  These are not directly visible to the system controller.  In order to add the additional network interface to the hardware asset, it is necessary to Declare it.  We will declare that we have a server with this additional NIC, but we will also  specify the existing GB_0 network so that Ops Center can associate the right resources together.  The GB_0 acts as sort of a key to tie our new declaration to the old system already discovered.  Go to the Assets tab, select All Assets, and then in the Actions tab, select Add Asset.  Rather than going through a discovery this time, we will manually declare a new asset. When we declare it, we will give the hostname, IP address, system model that match those that have already been discovered.  Then, we will declare both GB_0 with its existing MAC and the new GB_4 with its MAC.  Remember that we collected the MAC for GB_4 when we created its device alias. After you declare the asset, you will see the new NIC in the connectivity tab for the asset.  You will notice that only the NICs you listed when you declared it are seen now.  If you want Ops Center to see all of the existing NICs as well as the additional one, declare them as well.  Add the other GB_1, GB_2, GB_3 links and their MACs just as you did GB_0 and GB_4.  Installing the OS  Once you have declared the asset, you can create an OS Provisioning profile for Solaris 11 in the same way that you did for Solaris 10.  The only difference from any other provisioning profile you might have created already is the network to use for installation.  Again, use GB_N/netN where N is the interface number you used for your device alias and in your declaration.  And away you go.  When the system boots from the network, the automated installer (AI) is able to see which system manifest to use, based on the new MAC that was associated, and the system gets installed. {0} ok {0} ok printenv network-boot-argumentsnetwork-boot-arguments =  host-ip=10.140.204.234,router-ip=10.140.204.1,subnet-mask=255.255.254.0,hostname=atl-sewr-52,client-id=01002128204292,file=http://10.140.204.22:5555/cgi-bin/wanboot-cgi{0} ok {0} ok devalias net net                      /pci@780/pci@0/pci@1/network@0{0} ok devalias net4 net4                     /pci@780/pci@0/pci@8/network@0,2{0} ok devalias net /pci@780/pci@0/pci@8/network@0,2{0} ok setenv network-boot-arguments host-ip=10.140.204.234,router-ip=10.140.204.1,subnet-mask=255.255.254.0,hostname=atl-sewr-52,client-id=01002128204292,file=http://10.140.204.22:5555/cgi-bin/wanboot-cginetwork-boot-arguments =  host-ip=10.140.204.234,router-ip=10.140.204.1,subnet-mask=255.255.254.0,hostname=atl-sewr-52,client-id=01002128204292,file=http://10.140.204.22:5555/cgi-bin/wanboot-cgi{0} ok {0} ok boot net - installBoot device: /pci@780/pci@0/pci@8/network@0,2  File and args: - install/pci@780/pci@0/pci@8/network@0,2: 1000 Mbps link up<time unavailable> wanboot info: WAN boot messages->console<time unavailable> wanboot info: configuring /pci@780/pci@0/pci@8/network@0,2...SunOS Release 5.11 Version 11.0 64-bitCopyright (c) 1983, 2011, Oracle and/or its affiliates. All rights reserved.Remounting root read/writeProbing for device nodes ...Preparing network image for useDownloading solaris.zlib--2012-02-17 15:10:17--  http://10.140.204.22:5555/var/js/AI/sparc//solaris.zlibConnecting to 10.140.204.22:5555... connected.HTTP request sent, awaiting response... 200 OKLength: 126752256 (121M) [text/plain]Saving to: `/tmp/solaris.zlib'100%[======================================>] 126,752,256 28.6M/s   in 4.4s    2012-02-17 15:10:21 (27.3 MB/s) - `/tmp/solaris.zlib' saved [126752256/126752256] Conclusion So, why go to all of this trouble?  More and more, I find that customers are wiring their data center to only use higher speed networks - 10GbE only to the hosts.  Some customers are moving aggressively toward consolidated networks combining storage and network on CNA NICs.  All of this means that network-based provisioning cannot rely exclusively on the built-in network interfaces.  So, it's important to be able to provision a system using other than the built-in networks.  Turns out, that this is pretty straight-forward for both Solaris 10 and Solaris 11 and fits into the Ops Center deployment process quite nicely. Hopefully, you will be able to use this as you build out your own private cloud solutions with Ops Center.

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  • How to update correctly an Entity Model after changes of database structure?

    - by Slauma
    I've made some changes in the table structure and especially the relationships between tables in my SQL Server database. Now I want to update my Entity model based on this new database structure. Right clicking on the edmx file I find the option "Update model from database". But when I do this I get kind of a 50% update: The new columns appear in the Entity classes but I am confused about a lot of navigation properties which are still there in the model although the corresponding foreign key relationships do not exist anymore in the database. Am I doing something wrong? Or is there another option to update the model including deletion of navigation properties? Or do I have to delete those navigation properties manually in the model files? I am using Entity Framework Version 1 (VS 2008 SP1). Thanks for help in advance!

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  • nunit-console.exe problem with Mono

    - by prosseek
    I could make a dll for NUnit (http://stackoverflow.com/questions/2967726/nunit-test-under-mono), but when I tried to run in with nunit-console.exe I get the following error message. Runtime Environment - OS Version: Unix 10.3.0.0 CLR Version: 2.0.50727.1433 ( 2.6.4 (tarball Thu Apr 22 13:24:33 MDT 2010) ) ProcessModel: Default DomainUsage: Single Execution Runtime: mono-2.0 ** (/Users/smcho/bin/NUnit-2.5.5.10112/bin/net-2.0/nunit-console.exe:36800): WARNING **: The following assembly referenced from /private/var/folders/m4/m4u1hmP+FHOQaiZbHj1UCk+++TI/-Tmp-/nunit20/ShadowCopyCache/36800_634111616836311880/Tests_-22323139/assembly/shadow/54274fc2/118e035c_45a94c9e_00000001/mut.dll could not be loaded: Assembly: nunit.framework (assemblyref_index=1) Version: 2.5.5.10112 Public Key: 96d09a1eb7f44a77 System error: Invalid argument ** (/Users/smcho/bin/NUnit-2.5.5.10112/bin/net-2.0/nunit-console.exe:36800): WARNING **: Could not load file or assembly 'nunit.framework, Version=2.5.5.10112, Culture=neutral, PublicKeyToken=96d09a1eb7f44a77' or one of its dependencies. What might be wrong? I have nunit.framework.dll under /Users/smcho/bin/NUnit-2.5.5.10112/bin/net-2.0/framework, but it doesn't seem to know about this.

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  • Windows Azure: General Availability of Web Sites + Mobile Services, New AutoScale + Alerts Support, No Credit Card Needed for MSDN

    - by ScottGu
    This morning we released a major set of updates to Windows Azure.  These updates included: Web Sites: General Availability Release of Windows Azure Web Sites with SLA Mobile Services: General Availability Release of Windows Azure Mobile Services with SLA Auto-Scale: New automatic scaling support for Web Sites, Cloud Services and Virtual Machines Alerts/Notifications: New email alerting support for all Compute Services (Web Sites, Mobile Services, Cloud Services, and Virtual Machines) MSDN: No more credit card requirement for sign-up All of these improvements are now available to use immediately (note: some are still in preview).  Below are more details about them. Web Sites: General Availability Release of Windows Azure Web Sites I’m incredibly excited to announce the General Availability release of Windows Azure Web Sites. The Windows Azure Web Sites service is perfect for hosting a web presence, building customer engagement solutions, and delivering business web apps.  Today’s General Availability release means we are taking off the “preview” tag from the Free and Standard (formerly called reserved) tiers of Windows Azure Web Sites.  This means we are providing: A 99.9% monthly SLA (Service Level Agreement) for the Standard tier Microsoft Support available on a 24x7 basis (with plans that range from developer plans to enterprise Premier support) The Free tier runs in a shared compute environment and supports up to 10 web sites. While the Free tier does not come with an SLA, it works great for rapid development and testing and enables you to quickly spike out ideas at no cost. The Standard tier, which was called “Reserved” during the preview, runs using dedicated per-customer VM instances for great performance, isolation and scalability, and enables you to host up to 500 different Web sites within them.  You can easily scale your Standard instances on-demand using the Windows Azure Management Portal.  You can adjust VM instance sizes from a Small instance size (1 core, 1.75GB of RAM), up to a Medium instance size (2 core, 3.5GB of RAM), or Large instance (4 cores and 7 GB RAM).  You can choose to run between 1 and 10 Standard instances, enabling you to easily scale up your web backend to 40 cores of CPU and 70GB of RAM: Today’s release also includes general availability support for custom domain SSL certificate bindings for web sites running using the Standard tier. Customers will be able to utilize certificates they purchase for their custom domains and use either SNI or IP based SSL encryption. SNI encryption is available for all modern browsers and does not require an IP address.  SSL certificates can be used for individual sites or wild-card mapped across multiple sites (we charge extra for the use of a SSL cert – but the fee is per-cert and not per site which means you pay once for it regardless of how many sites you use it with).  Today’s release also includes the following new features: Auto-Scale support Today’s Windows Azure release adds preview support for Auto-Scaling web sites.  This enables you to setup automatic scale rules based on the activity of your instances – allowing you to automatically scale down (and save money) when they are below a CPU threshold you define, and automatically scale up quickly when traffic increases.  See below for more details. 64-bit and 32-bit mode support You can now choose to run your standard tier instances in either 32-bit or 64-bit mode (previously they only ran in 32-bit mode).  This enables you to address even more memory within individual web applications. Memory dumps Memory dumps can be very useful for diagnosing issues and debugging apps. Using a REST API, you can now get a memory dump of your sites, which you can then use for investigating issues in Visual Studio Debugger, WinDbg, and other tools. Scaling Sites Independently Prior to today’s release, all sites scaled up/down together whenever you scaled any site in a sub-region. So you may have had to keep your proof-of-concept or testing sites in a separate sub-region if you wanted to keep them in the Free tier. This will no longer be necessary.  Windows Azure Web Sites can now mix different tier levels in the same geographic sub-region. This allows you, for example, to selectively move some of your sites in the West US sub-region up to Standard tier when they require the features, scalability, and SLA of the Standard tier. Full pricing details on Windows Azure Web Sites can be found here.  Note that the “Shared Tier” of Windows Azure Web Sites remains in preview mode (and continues to have discounted preview pricing).  Mobile Services: General Availability Release of Windows Azure Mobile Services I’m incredibly excited to announce the General Availability release of Windows Azure Mobile Services.  Mobile Services is perfect for building scalable cloud back-ends for Windows 8.x, Windows Phone, Apple iOS, Android, and HTML/JavaScript applications.  Customers We’ve seen tremendous adoption of Windows Azure Mobile Services since we first previewed it last September, and more than 20,000 customers are now running mobile back-ends in production using it.  These customers range from startups like Yatterbox, to university students using Mobile Services to complete apps like Sly Fox in their spare time, to media giants like Verdens Gang finding new ways to deliver content, and telcos like TalkTalk Business delivering the up-to-the-minute information their customers require.  In today’s Build keynote, we demonstrated how TalkTalk Business is using Windows Azure Mobile Services to deliver service, outage and billing information to its customers, wherever they might be. Partners When we unveiled the source control and Custom API features I blogged about two weeks ago, we enabled a range of new scenarios, one of which is a more flexible way to work with third party services.  The following blogs, samples and tutorials from our partners cover great ways you can extend Mobile Services to help you build rich modern apps: New Relic allows developers to monitor and manage the end-to-end performance of iOS and Android applications connected to Mobile Services. SendGrid eliminates the complexity of sending email from Mobile Services, saving time and money, while providing reliable delivery to the inbox. Twilio provides a telephony infrastructure web service in the cloud that you can use with Mobile Services to integrate phone calls, text messages and IP voice communications into your mobile apps. Xamarin provides a Mobile Services add on to make it easy building cross-platform connected mobile aps. Pusher allows quickly and securely add scalable real-time messaging functionality to Mobile Services-based web and mobile apps. Visual Studio 2013 and Windows 8.1 This week during //build/ keynote, we demonstrated how Visual Studio 2013, Mobile Services and Windows 8.1 make building connected apps easier than ever. Developers building Windows 8 applications in Visual Studio can now connect them to Windows Azure Mobile Services by simply right clicking then choosing Add Connected Service. You can either create a new Mobile Service or choose existing Mobile Service in the Add Connected Service dialog. Once completed, Visual Studio adds a reference to Mobile Services SDK to your project and generates a Mobile Services client initialization snippet automatically. Add Push Notifications Push Notifications and Live Tiles are a key to building engaging experiences. Visual Studio 2013 and Mobile Services make it super easy to add push notifications to your Windows 8.1 app, by clicking Add a Push Notification item: The Add Push Notification wizard will then guide you through the registration with the Windows Store as well as connecting your app to a new or existing mobile service. Upon completion of the wizard, Visual Studio will configure your mobile service with the WNS credentials, as well as add sample logic to your client project and your mobile service that demonstrates how to send push notifications to your app. Server Explorer Integration In Visual Studio 2013 you can also now view your Mobile Services in the the Server Explorer. You can add tables, edit, and save server side scripts without ever leaving Visual Studio, as shown on the image below: Pricing With today’s general availability release we are announcing that we will be offering Mobile Services in three tiers – Free, Standard, and Premium.  Each tier is metered using a simple pricing model based on the # of API calls (bandwidth is included at no extra charge), and the Standard and Premium tiers are backed by 99.9% monthly SLAs.  You can elastically scale up or down the number of instances you have of each tier to increase the # of API requests your service can support – allowing you to efficiently scale as your business grows. The following table summarizes the new pricing model (full pricing details here):   You can find the full details of the new pricing model here. Build Conference Talks The //BUILD/ conference will be packed with sessions covering every aspect of developing connected applications with Mobile Services. The best part is that, even if you can’t be with us in San Francisco, every session is being streamed live. Be sure not to miss these talks: Mobile Services – Soup to Nuts — Josh Twist Building Cross-Platform Apps with Windows Azure Mobile Services — Chris Risner Connected Windows Phone Apps made Easy with Mobile Services — Yavor Georgiev Build Connected Windows 8.1 Apps with Mobile Services — Nick Harris Who’s that user? Identity in Mobile Apps — Dinesh Kulkarni Building REST Services with JavaScript — Nathan Totten Going Live and Beyond with Windows Azure Mobile Services — Kirill Gavrylyuk , Paul Batum Protips for Windows Azure Mobile Services — Chris Risner AutoScale: Dynamically scale up/down your app based on real-world usage One of the key benefits of Windows Azure is that you can dynamically scale your application in response to changing demand. In the past, though, you have had to either manually change the scale of your application, or use additional tooling (such as WASABi or MetricsHub) to automatically scale your application. Today, we’re announcing that AutoScale will be built-into Windows Azure directly.  With today’s release it is now enabled for Cloud Services, Virtual Machines and Web Sites (Mobile Services support will come soon). Auto-scale enables you to configure Windows Azure to automatically scale your application dynamically on your behalf (without any manual intervention) so you can achieve the ideal performance and cost balance. Once configured it will regularly adjust the number of instances running in response to the load in your application. Currently, we support two different load metrics: CPU percentage Storage queue depth (Cloud Services and Virtual Machines only) We’ll enable automatic scaling on even more scale metrics in future updates. When to use Auto-Scale The following are good criteria for services/apps that will benefit from the use of auto-scale: The service/app can scale horizontally (e.g. it can be duplicated to multiple instances) The service/app load changes over time If your app meets these criteria, then you should look to leverage auto-scale. How to Enable Auto-Scale To enable auto-scale, simply navigate to the Scale tab in the Windows Azure Management Portal for the app/service you wish to enable.  Within the scale tab turn the Auto-Scale setting on to either CPU or Queue (for Cloud Services and VMs) to enable Auto-Scale.  Then change the instance count and target CPU settings to configure the Auto-Scale ranges you want to maintain. The image below demonstrates how to enable Auto-Scale on a Windows Azure Web-Site.  I’ve configured the web-site so that it will run using between 1 and 5 VM instances.  The exact # used will depend on the aggregate CPU of the VMs using the 40-70% range I’ve configured below.  If the aggregate CPU goes above 70%, then Windows Azure will automatically add new VMs to the pool (up to the maximum of 5 instances I’ve configured it to use).  If the aggregate CPU drops below 40% then Windows Azure will automatically start shutting down VMs to save me money: Once you’ve turned auto-scale on, you can return to the Scale tab at any point and select Off to manually set the number of instances. Using the Auto-Scale Preview With today’s update you can now, in just a few minutes, have Windows Azure automatically adjust the number of instances you have running  in your apps to keep your service performant at an even better cost. Auto-scale is being released today as a preview feature, and will be free until General Availability. During preview, each subscription is limited to 10 separate auto-scale rules across all of the resources they have (Web sites, Cloud services or Virtual Machines). If you hit the 10 limit, you can disable auto-scale for any resource to enable it for another. Alerts and Notifications Starting today we are now providing the ability to configure threshold based alerts on monitoring metrics. This feature is available for compute services (cloud services, VM, websites and mobiles services). Alerts provide you the ability to get proactively notified of active or impending issues within your application.  You can define alert rules for: Virtual machine monitoring metrics that are collected from the host operating system (CPU percentage, network in/out, disk read bytes/sec and disk write bytes/sec) and on monitoring metrics from monitoring web endpoint urls (response time and uptime) that you have configured. Cloud service monitoring metrics that are collected from the host operating system (same as VM), monitoring metrics from the guest VM (from performance counters within the VM) and on monitoring metrics from monitoring web endpoint urls (response time and uptime) that you have configured. For Web Sites and Mobile Services, alerting rules can be configured on monitoring metrics from monitoring endpoint urls (response time and uptime) that you have configured. Creating Alert Rules You can add an alert rule for a monitoring metric by navigating to the Setting -> Alerts tab in the Windows Azure Management Portal. Click on the Add Rule button to create an alert rule. Give the alert rule a name and optionally add a description. Then pick the service which you want to define the alert rule on: The next step in the alert creation wizard will then filter the monitoring metrics based on the service you selected:   Once created the rule will show up in your alerts list within the settings tab: The rule above is defined as “not activated” since it hasn’t tripped over the CPU threshold we set.  If the CPU on the above machine goes over the limit, though, I’ll get an email notifying me from an Windows Azure Alerts email address ([email protected]). And when I log into the portal and revisit the alerts tab I’ll see it highlighted in red.  Clicking it will then enable me to see what is causing it to fail, as well as view the history of when it has happened in the past. Alert Notifications With today’s initial preview you can now easily create alerting rules based on monitoring metrics and get notified on active or impending issues within your application that require attention. During preview, each subscription is limited to 10 alert rules across all of the services that support alert rules. No More Credit Card Requirement for MSDN Subscribers Earlier this month (during TechEd 2013), Windows Azure announced that MSDN users will get Windows Azure Credits every month that they can use for any Windows Azure services they want. You can read details about this in my previous Dev/Test blog post. Today we are making further updates to enable an easier Windows Azure signup for MSDN users. MSDN users will now not be required to provide payment information (e.g. no credit card) during sign-up, so long as they use the service within the included monetary credit for the billing period. For usage beyond the monetary credit, they can enable overages by providing the payment information and remove the spending limit. This enables a super easy, one page sign-up experience for MSDN users.  Simply sign-up for your Windows Azure trial using the same Microsoft ID that you use to manage your MSDN account, then complete the one page sign-up form below and you will be able to spend your free monthly MSDN credits (up to $150 each month) on any Windows Azure resource for dev/test:   This makes it trivially easy for every MDSN customer to start using Windows Azure today.  If you haven’t signed up yet, I definitely recommend checking it out. Summary Today’s release includes a ton of great features that enable you to build even better cloud solutions.  If you don’t already have a Windows Azure account, you can sign-up for a free trial and start using all of the above features today.  Then visit the Windows Azure Developer Center to learn more about how to build apps with it. 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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  • Visual Studio 2010 Beta start without debugging Console wont stay open

    - by CousinVinny
    I want to keep the console (output) window open to view the output of the project I am working on. I have enabled the start without debugging option and added the button to the debugging toolbar, but alas it fails to keep it open nicely like in visual studio 2008. I have to add cin.getline() etc etc etc to get it to stay open, but I don't want to type it. Any suggestions as to alter it Visual Studio 2010 to keep it open, or any debugging tricks to make it easier to view output for longer than a flash. Visual Studio used to have a "Press any key to continue prompt" I want it back...

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  • Nullable One To One Relationships with Integer Keys in LINQ-to-SQL

    - by Craig Walker
    I have two objects (Foo and Bar) that have a one-to-zero-or-one relationship between them. So, Foo has a nullable foreign key reference to Bar.ID and a (nullbusted) unique index to enforce the "1" side. Bar.ID is an int, and so Foo.BarID is a nullable int. The problem occurs in the LINQ-to-SQL DBML mapping of .NET types to SQL datatypes. Since int is not a nullable type in .NET, it gets wrapped in a Nullable<int>. However, this is not the same type as int, and so Visual Studio gives me this error message when I try to create the OneToOne Association between them: Cannot create an association "Bar_Foo". Properties do not have matching types: "ID", "BarID". Is there a way around this?

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  • Scheduling runtime-specified Activity in Workflow 4 RC

    - by johnny g
    Hi, so I have this requirement to kick off Activities provided to me at run-time. To facilitate this, I have set up a WorkflowService that receives Activities as Xaml, hydrates them, and kicks them off. Sounds simple enough ... ... this is my WorkflowService in Xaml <Activity x:Class="Workflow.Services.WorkflowService.WorkflowService" ... xmlns:local1="clr-namespace:Workflow.Activities" > <Sequence sap:VirtualizedContainerService.HintSize="277,272"> <Sequence.Variables> <Variable x:TypeArguments="local:Workflow" Name="Workflow" /> </Sequence.Variables> <sap:WorkflowViewStateService.ViewState> <scg3:Dictionary x:TypeArguments="x:String, x:Object"> <x:Boolean x:Key="IsExpanded">True</x:Boolean> </scg3:Dictionary> </sap:WorkflowViewStateService.ViewState> <p:Receive CanCreateInstance="True" DisplayName="ReceiveSubmitWorkflow" sap:VirtualizedContainerService.HintSize="255,86" OperationName="SubmitWorkflow" ServiceContractName="IWorkflowService"> <p:ReceiveParametersContent> <OutArgument x:TypeArguments="local:Workflow" x:Key="workflow">[Workflow]</OutArgument> </p:ReceiveParametersContent> </p:Receive> <local1:InvokeActivity Activity="[ActivityXamlServices.Load(New System.IO.StringReader(Workflow.Xaml))]" sap:VirtualizedContainerService.HintSize="255,22" /> </Sequence> </Activity> ... which, except for repetitive use of "Workflow" is pretty straight forward. In fact, it's just a Sequence with a Receive and [currently] a custom Activity called InvokeActivity. Get to that in a bit. Receive Activity accepts a custom type, [DataContract] public class Workflow { [DataMember] public string Xaml { get; set; } } which contains a string whose contents are to be interpreted as Xaml. You can see the VB expression that then converts this Xaml to an Activity and passes it on. Now this second bit, the custom InvokeActivity is where I have questions. First question: 1) given an arbitrary task, provided at runtime [as described above] is it possible to kick off this Activity using Activities that ship with WF4RC, out of the box? I'm fairly new, and thought I did a good job going through the API and existing documentation, but may as well ask :) Second: 2) my first attempt at implementing a custom InvokeActivity looked like this public sealed class InvokeActivity : NativeActivity { private static readonly ILog _log = LogManager.GetLogger (typeof (InvokeActivity)); public InArgument<Activity> Activity { get; set; } public InvokeActivity () { _log.DebugFormat ("Instantiated."); } protected override void Execute (NativeActivityContext context) { Activity activity = Activity.Get (context); _log.DebugFormat ("Scheduling activity [{0}]...", activity.DisplayName); // throws exception to lack of metadata! :( ActivityInstance instance = context.ScheduleActivity (activity, OnComplete, OnFault); _log.DebugFormat ( "Scheduled activity [{0}] with instance id [{1}].", activity.DisplayName, instance.Id); } protected override void CacheMetadata (NativeActivityMetadata metadata) { // how does one add InArgument<T> to metadata? not easily // is my first guess base.CacheMetadata (metadata); } // private methods private void OnComplete ( NativeActivityContext context, ActivityInstance instance) { _log.DebugFormat ( "Scheduled activity [{0}] with instance id [{1}] has [{2}].", instance.Activity.DisplayName, instance.Id, instance.State); } private void OnFault ( NativeActivityFaultContext context, Exception exception, ActivityInstance instance) { _log.ErrorFormat ( @"Scheduled activity [{0}] with instance id [{1}] has faulted in state [{2}] {3}", instance.Activity.DisplayName, instance.Id, instance.State, exception.ToStringFullStackTrace ()); } } Which attempts to schedule the specified Activity within the current context. Unfortunately, however, this fails. When I attempt to schedule said Activity, the runtime returns with the following exception The provided activity was not part of this workflow definition when its metadata was being processed. The problematic activity named 'DynamicActivity' was provided by the activity named 'InvokeActivity'. Right, so the "dynamic" Activity provided at runtime is not a member of InvokeActivitys metadata. Googled and came across this. Couldn't sort out how to specify an InArgument<Activity> to metadata cache, so my second question is, naturally, how does one address this issue? Is it ill advised to use context.ScheduleActivity (...) in this manner? Third and final, 3) I have settled on this [simpler] solution for the time being, public sealed class InvokeActivity : NativeActivity { private static readonly ILog _log = LogManager.GetLogger (typeof (InvokeActivity)); public InArgument<Activity> Activity { get; set; } public InvokeActivity () { _log.DebugFormat ("Instantiated."); } protected override void Execute (NativeActivityContext context) { Activity activity = Activity.Get (context); _log.DebugFormat ("Invoking activity [{0}] ...", activity.DisplayName); // synchronous execution ... a little less than ideal, this // seems heavy handed, and not entirely semantic-equivalent // to what i want. i really want to invoke this runtime // activity as if it were one of my own, not a separate // process - wrong mentality? WorkflowInvoker.Invoke (activity); _log.DebugFormat ("Invoked activity [{0}].", activity.DisplayName); } } Which simply invokes specified task synchronously within its own runtime instance thingy [use of WF4 vernacular is certainly questionable]. Eventually, I would like to tap into WF's tracking and possibly persistance facilities. So my third and final question is, in terms of what I would like to do [ie kick off arbitrary workflows inbound from client applications] is this the preferred method? Alright, thanks in advance for your time and consideration :)

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  • Weighted random selection using Walker's Alias Method (c# implementation)

    - by Chuck Norris
    I was looking for this algorithm (algorithm which will randomly select from a list of elements where each element has different probability of being picked (weight) ) and found only python and c implementations, after I did a C# one, a bit different (but I think simpler) I thought I should share it, and ask your opinion ? this is it: using System; using System.Collections.Generic; using System.Linq; namespace ChuckNorris { class Program { static void Main(string[] args) { var oo = new Dictionary<string, int> { {"A",7}, {"B",1}, {"C",9}, {"D",8}, {"E",11}, }; var rnd = new Random(); var pick = rnd.Next(oo.Values.Sum()); var sum = 0; var res = ""; foreach (var o in oo) { sum += o.Value; if(sum >= pick) { res = o.Key; break; } } Console.WriteLine("result is "+ res); } } } if anyone can remake it in f# please post your code

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  • To get the parent node of a treeview in the TreeViewDragDropTarget in Silverlight

    - by Ramya
    Hi, I have created a TreeViewDragDropTarget like this, <controlsToolKit:TreeViewDragDropTarget msWindows:DragDrop.AllowDrop="False" ItemDroppedOnTarget="TreeViewDragDropTarget_ItemDroppedOnTarget" ItemDragCompleted="TreeViewDragDropTarget_ItemDragCompleted" AllowedSourceEffects="Copy"> <controlsToolKit:TreeViewDragDropTarget.Resources> <common:HierarchicalDataTemplate x:Key="hierarchicalTemplate" ItemsSource="{Binding ChildNode}"> <TextBlock Text="{Binding MainText, Mode=TwoWay}" TextWrapping="Wrap"/> </common:HierarchicalDataTemplate> </controlsToolKit:TreeViewDragDropTarget.Resources> <controls:TreeView x:Name="MainTreeView" BorderThickness="1" ItemTemplate="{StaticResource hierarchicalTemplate}" Background="Transparent" Cursor="Hand" BorderBrush="{x:Null}" VerticalAlignment="Top"/> </controlsToolKit:TreeViewDragDropTarget> All I am doing is dropping some text into the nodes of the treeview. I want to find the parent node of the drop target. How do I do it?

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  • SQL SERVER – SSMS: Memory Usage By Memory Optimized Objects Report

    - by Pinal Dave
    At conferences and at speaking engagements at the local UG, there is one question that keeps on coming which I wish were never asked. The question around, “Why is SQL Server using up all the memory and not releasing even when idle?” Well, the answer can be long and with the release of SQL Server 2014, this got even more complicated. This release of SQL Server 2014 has the option of introducing In-Memory OLTP which is completely new concept and our dependency on memory has increased multifold. In reality, nothing much changes but we have memory optimized objects (Tables and Stored Procedures) additional which are residing completely in memory and improving performance. As a DBA, it is humanly impossible to get a hang of all the innovations and the new features introduced in the next version. So today’s blog is around the report added to SSMS which gives a high level view of this new feature addition. This reports is available only from SQL Server 2014 onwards because the feature was introduced in SQL Server 2014. Earlier versions of SQL Server Management Studio would not show the report in the list. If we try to launch the report on the database which is not having In-Memory File group defined, then we would see the message in report. To demonstrate, I have created new fresh database called MemoryOptimizedDB with no special file group. Here is the query used to identify whether a database has memory-optimized file group or not. SELECT TOP(1) 1 FROM sys.filegroups FG WHERE FG.[type] = 'FX' Once we add filegroup using below command, we would see different version of report. USE [master] GO ALTER DATABASE [MemoryOptimizedDB] ADD FILEGROUP [IMO_FG] CONTAINS MEMORY_OPTIMIZED_DATA GO The report is still empty because we have not defined any Memory Optimized table in the database.  Total allocated size is shown as 0 MB. Now, let’s add the folder location into the filegroup and also created few in-memory tables. We have used the nomenclature of IMO to denote “InMemory Optimized” objects. USE [master] GO ALTER DATABASE [MemoryOptimizedDB] ADD FILE ( NAME = N'MemoryOptimizedDB_IMO', FILENAME = N'E:\Program Files\Microsoft SQL Server\MSSQL12.SQL2014\MSSQL\DATA\MemoryOptimizedDB_IMO') TO FILEGROUP [IMO_FG] GO You may have to change the path based on your SQL Server configuration. Below is the script to create the table. USE MemoryOptimizedDB GO --Drop table if it already exists. IF OBJECT_ID('dbo.SQLAuthority','U') IS NOT NULL DROP TABLE dbo.SQLAuthority GO CREATE TABLE dbo.SQLAuthority ( ID INT IDENTITY NOT NULL, Name CHAR(500)  COLLATE Latin1_General_100_BIN2 NOT NULL DEFAULT 'Pinal', CONSTRAINT PK_SQLAuthority_ID PRIMARY KEY NONCLUSTERED (ID), INDEX hash_index_sample_memoryoptimizedtable_c2 HASH (Name) WITH (BUCKET_COUNT = 131072) ) WITH (MEMORY_OPTIMIZED = ON, DURABILITY = SCHEMA_AND_DATA) GO As soon as above script is executed, table and index both are created. If we run the report again, we would see something like below. Notice that table memory is zero but index is using memory. This is due to the fact that hash index needs memory to manage the buckets created. So even if table is empty, index would consume memory. More about the internals of how In-Memory indexes and tables work will be reserved for future posts. Now, use below script to populate the table with 10000 rows INSERT INTO SQLAuthority VALUES (DEFAULT) GO 10000 Here is the same report after inserting 1000 rows into our InMemory table.    There are total three sections in the whole report. Total Memory consumed by In-Memory Objects Pie chart showing memory distribution based on type of consumer – table, index and system. Details of memory usage by each table. The information about all three is taken from one single DMV, sys.dm_db_xtp_table_memory_stats This DMV contains memory usage statistics for both user and system In-Memory tables. If we query the DMV and look at data, we can easily notice that the system tables have negative object IDs.  So, to look at user table memory usage, below is the over-simplified version of query. USE MemoryOptimizedDB GO SELECT OBJECT_NAME(OBJECT_ID), * FROM sys.dm_db_xtp_table_memory_stats WHERE OBJECT_ID > 0 GO This report would help DBA to identify which in-memory object taking lot of memory which can be used as a pointer for designing solution. I am sure in future we will discuss at lengths the whole concept of In-Memory tables in detail over this blog. To read more about In-Memory OLTP, have a look at In-Memory OLTP Series at Balmukund’s Blog. Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Server Management Studio, SQL Tips and Tricks, T SQL Tagged: SQL Memory, SQL Reports

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  • HttpRuntime.Cache scavenging default behavior?

    - by Rire1979
    When adding items using the default insert method Insert(key, value) and as such using the default behavior of HttpRuntime.Cache, when does the scavenging take place? The limit on the application pool that hosts my application is 0 (unlimited)... but I see no way to find out how big the cache can get before scavenging occurs? The problem is I am caching a potentially very large amount of data but I have limited memory on the server and I want to avoid recycling of the app pool. I am asking in the context of IIS6 and IIS7. Thank you.

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  • ADO Entity Framework 4 to WPF Datagrid. DatagridComboBox nightmare.

    - by Jason
    The WPF datagrid -seems- like it's going to work, but the combobox implementation does not work straight from the designer. So I'm left wandering around in the XAML randomly changing things trying to get it to work. The problems are numerous. I want to display a foreign key relationship (with drop down) instead of a bunch of numbers for a selection. It seems like it shouldn't be this hard. I can get the right values to show up (their description instead of an ID), but the table freaks out thinking that all the values have been modified. If I select a drop down, it refuses to allow me to edit anything else. I want to chalk this up as a .NET bug, but since I'm new to WPF datagrids, it's probably just me. Here is the code. <DataGridComboBoxColumn Header="Make Up" ItemsSource="{Binding Source={StaticResource materialMakeUpTypesViewSource}}" DisplayMemberPath="Description" TextBinding="{Binding Path=MaterialMakeUpType.Description}" SelectedItemBinding="{Binding Path=MaterialMakeUpType.Description}" SelectedValueBinding="{Binding Path=MaterialMakeUpType.ID}" />

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  • Add/remove Cake named URL parameter for a link

    - by sibidiba
    Using CakePHP 1.3 there are named parameters in the URL like .../name:value/... These are used for example by pagination links .../page:2/key:date/sort:desc/... How to generate links with HtmlHelper::link() adding/deleting such named parameters from the current URL? Basically I want create links to add/remove/modify the category:ID named parameter in the current URL. It must not touch the URL, anchor, other named parameters, GET parameters in the URL. Or how can I pass named parameters to HtmlHelper::link()?

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  • OAuth in C# as a client

    - by Redth
    Hi, I've been given 6 bits of information to access some data from a website: Website Json Url (eg: http://somesite.com/items/list.json) OAuth Authorization Url (eg: http://somesite.com/oauth/authorization) OAuth Request Url (eg: http://somesite.com/oauth/request) OAuth Access Url (eg: http://somesite.com/oauth/access) Client Key (eg: 12345678) Client Secret (eg: abcdefghijklmnop) Now, I've looked at DotNetOpenAuth and OAuth.NET libraries, and while I'm sure they are very capable of doing what I need, I just can't figure out how to use either in this way. Could someone post some sample code of how to consume the Url (Point 1.) in either library (or any other way that may work just as well)? Thanks!

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  • Spring - adding BindingResult to newly created model attribute

    - by Max
    My task is - to create a model attribute by given request parameters, to validate it (in same method) and to give it whole to the View. I was given this code: //Create the model attribute by request parameters Promotion promotion = Promotions.get(someRequestParam); //Add the attribute to the model modelMap.addAttribute("promotion", promotion); if (!promotion.validate()) { BindingResult errors = new BeanPropertyBindingResult(promotion, "promotion"); errors.reject("promotion.invalid"); //TODO: This is the part I don't like model.put(BindingResult.MODEL_KEY_PREFIX + "promotion", errors); } This thing sure works, but that part with creating key with MODEL_KEY_PREFIX and attribute name looks very hackish and not a Spring style to me. Is there a way to make the same thing prettier?

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  • netbeans editor loses focus on editor and gives it to the menubar

    - by aboutblank
    Hi all, I am newbie of using Netbeans and i have Netbeans 6.5 on XP. So, here is my problem: when i am working on Netbeans and switch to an another task and then come back later, editor of the Netbeans losts the focus and the menubar gains it. I don't want to press ALT key again to re-focus on the editor. I made some search on help contents of the Netbeans and google and i couldn't find any solution. Have any of you got an idea to solve this problem? By the way, i am sorry about my unfluent English. Have a nice day!

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  • Install Control Center Agent on Oracle Application Server

    - by qianqian.wu
    Control Center Agent (CCA) The Control Center Agent is the OWB component that runs the Template Mappings in the Oracle Containers for J2EE (OC4J) server; also referred to as the J2EE Runtime. The Control Center Agent provides a Java-based runtime environment that can be installed on Oracle and non-Oracle database hosts. The Control Center Agent provides fundamental infrastructure for the heterogeneous, Code Template-based mapping support and Web services-related features of OWB in this release. In Oracle Warehouse Builder 11gR2 the Control Center Agent, by default will run in the built-in OC4J that is bundled in the Oracle Home. Besides that, you also have ability to install the Control Center Agent in an Oracle Application Server install. In this article, you will find step-by-step instructions how to install the Control Center Agent on an Oracle Application Server instance. The instructions cover the following tasks: Task 1: Install and Configure the Application Server Task 2: Deploy the Control Center Agent to the Application Server Task 3: Optional Configuration Tasks   Task 1: Install and Configure the Application Server Before configuring the Application Server, you need to install it from Oracle Application Server CD-ROM, or by downloading the installation program from Oracle Technology Network (OTN). Once the installation is completed, you are ready to configure the Application Server. The purpose of the configuration task is to make sure the Control Center Agent ear file can be deployed and runs in the Application Server successfully. The essential configuration tasks are outlined below: · Modify the OC4J Startup Script · Set up Control Center Agent Server Side Logging · Set up Audit Table Data Source · Copy ct_permissions.properties File · Set up Security Roles for Control Center Agent · Create JMS Queues · Install JDBC Drivers to OC4J Modify the OC4J Startup Script The OC4J startup script “opmn.xml” is located in Application Server configuration directory, $AS_HOME/opmn/conf. $AS_HOME stands for the root home directory of the application server. Open the file opmn.xml in a text editor, and alter the contents of the file as displayed in the following sample. You need to make sure that: The MaxPerSize is set to 128M. This is to ensure that you allocate enough PermGen space to OC4J to run Control Center Agent. This will prevent java.lang.OutOfMemoryError when running the agent. The Python.path sets the path for the Python library files used by the Control Center Agent: jython_lib.zip and jython_owblib.jar. These two files are in the $OWB_HOME/owb/lib/int directory, where $OWB_HOME is the directory where owb is installed. · The km_security_needed determines whether restrictions will be applied to the kinds of operating system commands allowed to be executed by the OWB Code Template script executed by Control Center Agent. Setting km_security_needed to “true” enforces such restriction while setting it to “false” removes such restrictions. Set up Control Center Agent Server Side Logging Ensure that you are in the Application Server configuration directory, $AS_HOME/j2ee/home/config. Open the file j2ee-logging.xml in a text editor and add the following lines to the log handler section. The jrt-internal-log-handler is the handler used by Control Center Agent runtime logger to create log files. Then add the following entry into the loggers section to create the logger for Control Center Agent runtime auditing. Set up Audit Table Data Source To enable Audit Table logging, a managed data source and connection pool need to be set up before Control Center Agent deployment. Ensure that you are in the Application Server configuration directory, $AS_HOME/j2ee/home/config. Open the file data-sources.xml in a text editor. Define the audit data source shown below in the file, <managed-data-source name="AuditDS" connection-pool-name="OWBSYS Audit   Connection Pool" jndi-name="jdbc/AuditDS"/> <connection-pool name="OWBSYS Audit Connection Pool">   <connection-factory factory-class="oracle.jdbc.pool.OracleDataSource"     user="owbsys_audit" password="owbsys_audit"     url="jdbc:oracle:thin:@//localhost:1521/ORCL"/> </connection-pool> Copy ct_permissions.properties File The ct_permissions.properties can be obtained from $OWB_HOME /owb/jrt/config/ directory. You need to copy the file to $AS_HOME/j2ee/home/config directory.This properties file takes effect when the setting km-security is set to true in Control Center Agent. By default the ALLOWED_CMD is commented out in ct_permissions.properties file. This prevents all system command from being invoked from scripts executed in Control Center Agent (when km-security is set to true). To allow certain system commands to be invoked, ALLOWED_CMD needs to be uncommented out, and the system commands (allowed to be invoked) need to be added to the ALLOWED_CMD. Set up Security Roles for Control Center Agent You can set up the Control Center Agent security roles through Oracle Enterprise Manager. In a web browser, navigate to Enterprise Manager Homepage (e.g. http://hostname:8889/em). 1. Log in using the oc4jadmin credentials. After the Cluster Topology page is loaded, click home (the OC4J instance). This takes you to the home page of the OC4J instance. On the OC4J home screen, click the Administration tab. On the Administration Tasks screen, expand Security. Click the task icon next to Security Providers. 2. On Security Providers page click on the button “Instance Level Security”. On Instance Level Security page, go to “Realms” tab. You will see a row for the default realm “jazn.com” in the results table. It has a “Roles” column and a “Users” column. Click on the number in “Roles” column. In the “Roles” page it will display all the roles available for the realm. Click on “Create” button to create a new role “OWB_J2EE_ EXECUTOR”. 3. On the Add Role screen, enter Name OWB_J2EE_EXECUTOR, and click OK. 4. Follow the same steps as before, and create a new role “OWB_J2EE_OPERATOR”. 5. Assign role “oc4j-administrators” and “OWB_J2EE_EXECUTOR” to the role “OWB_J2EE_OPERATOR” by moving these roles from “Available Roles” and click “OK” to save. 6. Go back to Instance Level Security page and create a new role “OWB_J2EE_ADMINISTRATOR”. 7. Assign roles “OWB_J2EE_ OPERATOR” and “OWB_J2EE_EXECUTOR” to the role “OWB_J2EE_ ADMINISTRATOR” by moving these roles from “Available Roles” and click “OK” to save. 8.Go back to Instance Level Security page. This time, click on the number in “Users” column for the realm “jazn.com”. In the “Users” page, it shows all the users defined for this realm. Locate the user “oc4jadmin” in the results table and click on it. 9. Assign the roles “OWB_J2EE_ADMINISTRATOR” and “oc4j-app-administrators” to this user by moving the role from the “Available Roles” selection box to “Selected Roles” box and click “Apply” to save. 10. Go back to Instance Level Security page and create a new role “OWB_INTERNAL_USERS”, assign no user or role to this role. Simply click “OK” to create this role. Now you have finished creating the security roles required for Control Center Agent. Create JMS Queues You need to create two JMS queues for Control Center Agent: owbQueue and abort_owbQueue. 1. Now go to OC4J home Page. On the OC4J home screen, click the Administration tab. On the Administration Tasks screen, expand Services and then expand Enterprise Messaging Service. Click the task icon next to JMS Destinations. 2. On JMS Destinations page, click “Create New” button to create a new JMS queue. On Add Destination page, choose “Queue” as Destination Type. Put “owbQueue” as Destination Name. Select “In Memory Persistence Only” as the Persistence Type and put “jms/owbQueue” as JNDI Location and click on “OK” to finish. 3. Follow the same instruction as above to create the owb_abortQueue. Now you have finished creating the JMS queues required for Control Center Agent. Install JDBC Drivers to OC4J In order to execute Code Templates using commercial databases other than Oracle, e.g. DB2, SQL Server etc, the corresponding jdbc driver files need to be added to $AS_HOME/j2ee/home/applib directory. 1. To install other JDBC drivers to OC4J, first obtain the .jar file containing the JDBC driver. All the external JDBC drivers .jar files can be found in the directory: $OWB_HOME/owb/lib/ext/. For DB2, the files needed are db2jcc.jar and db2jcc_license_cu.jar. For SQL Server the file is sqljdbc.jar. For sunopsis JDBC drivers, the file needed is snpsxmlo.jar. 2. Copy the required JDBC driver file into the directory $AS_HOME/j2ee/home/applib. Now you have finished the Application Server configuration. To make the configuration to take an effect, you need to restart the Application Server.   Task 2: Deploy the Control Center Agent to the Application Server Now you can deploy the Control Center Agent to the Application Server. In a web browser, navigate to Enterprise Manager Homepage (e.g. http://hostname:8889/em). 1. Log in using the oc4jadmin credentials. After the Cluster Topology page is loaded, click home (the OC4J instance). This takes you to the home page of the OC4J instance. On the OC4J home screen, click the Applications tab. Click Deploy to begin deploying Control Center Agent. 2. On the Deploy: Select Archive screen, under Archive, select Archive is present on local host. Upload the archive to the server where Application Server Control is running. Click Browse and locate the jrt.ear file in the $OWB_HOME/owb/jrt/applications directory. Under Deployment Plan, select Automatically create a new deployment plan. Click Next. 3. Wait for the ear file to be uploaded to Application Server. On the Deploy: Application Attributes screen, enter Application Name jrt, and Context Root jrt. Leave the other attributes at their default values. Click Next. 4. On Deploy: Deployment Settings screen, leave all attributes at their default values, and click Deploy. This will take about 1 minute or so and when the application is deployed successfully, a confirmation message will be displayed. Now the Control Center Agent is started automatically. Go back to OC4J home page and click on Applications tab to make sure the deployed application jrt is showing in the applications list.   Task 3: Optional Configuration Tasks The optional configuration tasks contain: · Secure Control Center Agent Web Service · Setting the PATH Environment Variable Secure Control Center Agent Web Service If you want to use JRTWebService with a secure website, you need to do the following steps, 1. Create a file “secure-web-site.xml” in the $AS_HOME/j2ee/home/config directory. The file can be obtained from $OWB_HOME/owb/jrt/config directory. A sample secure-web-site.xml is shown as below. We need to modify the “protocol” to “https”, and “secure” to “true”, also choose an port as the secure http port. Also we need to add the entry “ssl-config” in the file. Remember to use the absolute path for the key store file. 2. Modify the file “server.xml” that is located at $AS_HOME/j2ee/home/config directory. Then add the <web-site> element in the file for the secure-web-site. 3. Create a key store file “serverkeystore.jks” in the $AS_HOME/j2ee/home/config directory. The file can be obtained from $OWB_HOME/owb/jrt/config directory. After the three files are altered, restart the application server. Now you can access the JRTWebService in SSL way through https://hostname:4443/jrt/webservice. Setting the PATH Environment Variable Sometimes, some system commands such as linux ls, sh etc, can not be executed successfully during the script execution due to they are not found in PATH. To ensure they work normally, you can setup the environment variable PATH. Let’s navigate to the Enterprise Manager Homepage. 1. Go to OC4J home screen and click the Administration tab. Expand Administration Tasks, then expand Properties. Click the task icon next to Server Properties. 2. On the Server Properties screen, scroll down to Environment Variables section. Under Environment Variables, click Add Another Row. Enter PATH in Name, and fill Value with directories that contain the system commands. Click Apply.   After you work through this article, I believe you have developed a deeper understanding of the Control Center Agent installation process, and you can apply this knowledge in other installation plan such as Control Center Agent installation on Standalone OC4J.

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  • Google Reader API HTTP Response parsing (Objective C)

    - by JustinXXVII
    Using the API, trying to get items in a specific feed returns this: {“direction”:”ltr”,”id”:”feed/http://arstechnica.com/index.rssx”,”title”:”Ars Technica”,”description”:”The Art of Technology”,”self”:[{"href":"http://www.google.com/reader/api/0/stream/contents/feed/http://arstechnica.com/index.rssx?ot\u003d1273193172856169\u0026r\u003dn\u0026xt\u003duser/-/state/com.google/read\u0026n\u003d4\u0026ck\u003d1273193873\u0026client\u003diPadReader"}],”alternate”:[{"href":"http://arstechnica.com/index.php","type":"text/html"}],”updated”:1273193873,”items”:[]} They look like key/value pairs but it’s plain text with UTF8 String encoding and won’t encode into a dictionary. I’m using Objective-C and I’m not sure where to go from here. So far I’ve been able to parse the XML response for unread items, but parsing the plain-text doesn’t look feasible. What is your practice?

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  • Django ORM: Ordering w/ aggregate functions — None special treatment

    - by deno
    Hi, I'm doing query like that: SomeObject.objects.annotate(something=Avg('something')).order_by(something).all() Now, I normally have an aggregate field in my model that I use with Django signals to keep in sync, however in this case perfomance isn't an issue so I thought I'd keep it simple and just use subqueries. This approach, however, presented an unexpected issue: It all works grate if aggregate function results are like this: [5.0, 4.0, 6.0 … (etc, just numbers)] However if you mix in some Nones than it's being ordered like this: [None, 5.0, 4.0 …] The issue is that None has higher value than any number, while it should have value at most of 0. I'm using PostgreSQL and haven't tested w/ other DBs. I haven't actually checked what query is generated etc. I worked it around by just sorting in memory: sorted(…, key=lambda _:_.avg_rating if _.avg_rating is not None else 0) So I'm just curious if you know a way to do it w/ just Django ORM. Perhaps .where? or something… Kind regards

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  • ASP.NET and HTML5 Local Storage

    - by Stephen Walther
    My favorite feature of HTML5, hands-down, is HTML5 local storage (aka DOM storage). By taking advantage of HTML5 local storage, you can dramatically improve the performance of your data-driven ASP.NET applications by caching data in the browser persistently. Think of HTML5 local storage like browser cookies, but much better. Like cookies, local storage is persistent. When you add something to browser local storage, it remains there when the user returns to the website (possibly days or months later). Importantly, unlike the cookie storage limitation of 4KB, you can store up to 10 megabytes in HTML5 local storage. Because HTML5 local storage works with the latest versions of all modern browsers (IE, Firefox, Chrome, Safari), you can start taking advantage of this HTML5 feature in your applications right now. Why use HTML5 Local Storage? I use HTML5 Local Storage in the JavaScript Reference application: http://Superexpert.com/JavaScriptReference The JavaScript Reference application is an HTML5 app that provides an interactive reference for all of the syntax elements of JavaScript (You can read more about the application and download the source code for the application here). When you open the application for the first time, all of the entries are transferred from the server to the browser (all 300+ entries). All of the entries are stored in local storage. When you open the application in the future, only changes are transferred from the server to the browser. The benefit of this approach is that the application performs extremely fast. When you click the details link to view details on a particular entry, the entry details appear instantly because all of the entries are stored on the client machine. When you perform key-up searches, by typing in the filter textbox, matching entries are displayed very quickly because the entries are being filtered on the local machine. This approach can have a dramatic effect on the performance of any interactive data-driven web application. Interacting with data on the client is almost always faster than interacting with the same data on the server. Retrieving Data from the Server In the JavaScript Reference application, I use Microsoft WCF Data Services to expose data to the browser. WCF Data Services generates a REST interface for your data automatically. Here are the steps: Create your database tables in Microsoft SQL Server. For example, I created a database named ReferenceDB and a database table named Entities. Use the Entity Framework to generate your data model. For example, I used the Entity Framework to generate a class named ReferenceDBEntities and a class named Entities. Expose your data through WCF Data Services. I added a WCF Data Service to my project and modified the data service class to look like this:   using System.Data.Services; using System.Data.Services.Common; using System.Web; using JavaScriptReference.Models; namespace JavaScriptReference.Services { [System.ServiceModel.ServiceBehavior(IncludeExceptionDetailInFaults = true)] public class EntryService : DataService<ReferenceDBEntities> { // This method is called only once to initialize service-wide policies. public static void InitializeService(DataServiceConfiguration config) { config.UseVerboseErrors = true; config.SetEntitySetAccessRule("*", EntitySetRights.All); config.DataServiceBehavior.MaxProtocolVersion = DataServiceProtocolVersion.V2; } // Define a change interceptor for the Products entity set. [ChangeInterceptor("Entries")] public void OnChangeEntries(Entry entry, UpdateOperations operations) { if (!HttpContext.Current.Request.IsAuthenticated) { throw new DataServiceException("Cannot update reference unless authenticated."); } } } }     The WCF data service is named EntryService. Notice that it derives from DataService<ReferenceEntitites>. Because it derives from DataService<ReferenceEntities>, the data service exposes the contents of the ReferenceEntitiesDB database. In the code above, I defined a ChangeInterceptor to prevent un-authenticated users from making changes to the database. Anyone can retrieve data through the service, but only authenticated users are allowed to make changes. After you expose data through a WCF Data Service, you can use jQuery to retrieve the data by performing an Ajax call. For example, I am using an Ajax call that looks something like this to retrieve the JavaScript entries from the EntryService.svc data service: $.ajax({ dataType: "json", url: “/Services/EntryService.svc/Entries”, success: function (result) { var data = callback(result["d"]); } });     Notice that you must unwrap the data using result[“d”]. After you unwrap the data, you have a JavaScript array of the entries. I’m transferring all 300+ entries from the server to the client when the application is opened for the first time. In other words, I transfer the entire database from the server to the client, once and only once, when the application is opened for the first time. The data is transferred using JSON. Here is a fragment: { "d" : [ { "__metadata": { "uri": "http://superexpert.com/javascriptreference/Services/EntryService.svc/Entries(1)", "type": "ReferenceDBModel.Entry" }, "Id": 1, "Name": "Global", "Browsers": "ff3_6,ie8,ie9,c8,sf5,es3,es5", "Syntax": "object", "ShortDescription": "Contains global variables and functions", "FullDescription": "<p>\nThe Global object is determined by the host environment. In web browsers, the Global object is the same as the windows object.\n</p>\n<p>\nYou can use the keyword <code>this</code> to refer to the Global object when in the global context (outside of any function).\n</p>\n<p>\nThe Global object holds all global variables and functions. For example, the following code demonstrates that the global <code>movieTitle</code> variable refers to the same thing as <code>window.movieTitle</code> and <code>this.movieTitle</code>.\n</p>\n<pre>\nvar movieTitle = \"Star Wars\";\nconsole.log(movieTitle === this.movieTitle); // true\nconsole.log(movieTitle === window.movieTitle); // true\n</pre>\n", "LastUpdated": "634298578273756641", "IsDeleted": false, "OwnerId": null }, { "__metadata": { "uri": "http://superexpert.com/javascriptreference/Services/EntryService.svc/Entries(2)", "type": "ReferenceDBModel.Entry" }, "Id": 2, "Name": "eval(string)", "Browsers": "ff3_6,ie8,ie9,c8,sf5,es3,es5", "Syntax": "function", "ShortDescription": "Evaluates and executes JavaScript code dynamically", "FullDescription": "<p>\nThe following code evaluates and executes the string \"3+5\" at runtime.\n</p>\n<pre>\nvar result = eval(\"3+5\");\nconsole.log(result); // returns 8\n</pre>\n<p>\nYou can rewrite the code above like this:\n</p>\n<pre>\nvar result;\neval(\"result = 3+5\");\nconsole.log(result);\n</pre>", "LastUpdated": "634298580913817644", "IsDeleted": false, "OwnerId": 1 } … ]} I worried about the amount of time that it would take to transfer the records. According to Google Chome, it takes about 5 seconds to retrieve all 300+ records on a broadband connection over the Internet. 5 seconds is a small price to pay to avoid performing any server fetches of the data in the future. And here are the estimated times using different types of connections using Fiddler: Notice that using a modem, it takes 33 seconds to download the database. 33 seconds is a significant chunk of time. So, I would not use the approach of transferring the entire database up front if you expect a significant portion of your website audience to connect to your website with a modem. Adding Data to HTML5 Local Storage After the JavaScript entries are retrieved from the server, the entries are stored in HTML5 local storage. Here’s the reference documentation for HTML5 storage for Internet Explorer: http://msdn.microsoft.com/en-us/library/cc197062(VS.85).aspx You access local storage by accessing the windows.localStorage object in JavaScript. This object contains key/value pairs. For example, you can use the following JavaScript code to add a new item to local storage: <script type="text/javascript"> window.localStorage.setItem("message", "Hello World!"); </script>   You can use the Google Chrome Storage tab in the Developer Tools (hit CTRL-SHIFT I in Chrome) to view items added to local storage: After you add an item to local storage, you can read it at any time in the future by using the window.localStorage.getItem() method: <script type="text/javascript"> window.localStorage.setItem("message", "Hello World!"); </script>   You only can add strings to local storage and not JavaScript objects such as arrays. Therefore, before adding a JavaScript object to local storage, you need to convert it into a JSON string. In the JavaScript Reference application, I use a wrapper around local storage that looks something like this: function Storage() { this.get = function (name) { return JSON.parse(window.localStorage.getItem(name)); }; this.set = function (name, value) { window.localStorage.setItem(name, JSON.stringify(value)); }; this.clear = function () { window.localStorage.clear(); }; }   If you use the wrapper above, then you can add arbitrary JavaScript objects to local storage like this: var store = new Storage(); // Add array to storage var products = [ {name:"Fish", price:2.33}, {name:"Bacon", price:1.33} ]; store.set("products", products); // Retrieve items from storage var products = store.get("products");   Modern browsers support the JSON object natively. If you need the script above to work with older browsers then you should download the JSON2.js library from: https://github.com/douglascrockford/JSON-js The JSON2 library will use the native JSON object if a browser already supports JSON. Merging Server Changes with Browser Local Storage When you first open the JavaScript Reference application, the entire database of JavaScript entries is transferred from the server to the browser. Two items are added to local storage: entries and entriesLastUpdated. The first item contains the entire entries database (a big JSON string of entries). The second item, a timestamp, represents the version of the entries. Whenever you open the JavaScript Reference in the future, the entriesLastUpdated timestamp is passed to the server. Only records that have been deleted, updated, or added since entriesLastUpdated are transferred to the browser. The OData query to get the latest updates looks like this: http://superexpert.com/javascriptreference/Services/EntryService.svc/Entries?$filter=(LastUpdated%20gt%20634301199890494792L) If you remove URL encoding, the query looks like this: http://superexpert.com/javascriptreference/Services/EntryService.svc/Entries?$filter=(LastUpdated gt 634301199890494792L) This query returns only those entries where the value of LastUpdated > 634301199890494792 (the version timestamp). The changes – new JavaScript entries, deleted entries, and updated entries – are merged with the existing entries in local storage. The JavaScript code for performing the merge is contained in the EntriesHelper.js file. The merge() method looks like this:   merge: function (oldEntries, newEntries) { // concat (this performs the add) oldEntries = oldEntries || []; var mergedEntries = oldEntries.concat(newEntries); // sort this.sortByIdThenLastUpdated(mergedEntries); // prune duplicates (this performs the update) mergedEntries = this.pruneDuplicates(mergedEntries); // delete mergedEntries = this.removeIsDeleted(mergedEntries); // Sort this.sortByName(mergedEntries); return mergedEntries; },   The contents of local storage are then updated with the merged entries. I spent several hours writing the merge() method (much longer than I expected). I found two resources to be extremely useful. First, I wrote extensive unit tests for the merge() method. I wrote the unit tests using server-side JavaScript. I describe this approach to writing unit tests in this blog entry. The unit tests are included in the JavaScript Reference source code. Second, I found the following blog entry to be super useful (thanks Nick!): http://nicksnettravels.builttoroam.com/post/2010/08/03/OData-Synchronization-with-WCF-Data-Services.aspx One big challenge that I encountered involved timestamps. I originally tried to store an actual UTC time as the value of the entriesLastUpdated item. I quickly discovered that trying to work with dates in JSON turned out to be a big can of worms that I did not want to open. Next, I tried to use a SQL timestamp column. However, I learned that OData cannot handle the timestamp data type when doing a filter query. Therefore, I ended up using a bigint column in SQL and manually creating the value when a record is updated. I overrode the SaveChanges() method to look something like this: public override int SaveChanges(SaveOptions options) { var changes = this.ObjectStateManager.GetObjectStateEntries( EntityState.Modified | EntityState.Added | EntityState.Deleted); foreach (var change in changes) { var entity = change.Entity as IEntityTracking; if (entity != null) { entity.LastUpdated = DateTime.Now.Ticks; } } return base.SaveChanges(options); }   Notice that I assign Date.Now.Ticks to the entity.LastUpdated property whenever an entry is modified, added, or deleted. Summary After building the JavaScript Reference application, I am convinced that HTML5 local storage can have a dramatic impact on the performance of any data-driven web application. If you are building a web application that involves extensive interaction with data then I recommend that you take advantage of this new feature included in the HTML5 standard.

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  • Auto_increment values in InnoDB?

    - by Timmy
    I've been using InnoDB for a project, and relying on auto_increment. This is not a problem for most of the tables, but for tables with deletion, this might be an issue: AUTO_INCREMENT Handling in InnoDB particularly this part: AUTO_INCREMENT column named ai_col: After a server startup, for the first insert into a table t, InnoDB executes the equivalent of this statement: SELECT MAX(ai_col) FROM t FOR UPDATE; InnoDB increments by one the value retrieved by the statement and assigns it to the column and to the auto-increment counter for the table. This is a problem because while it ensures that within the table, the key is unique, there are foreign keys to this table where those keys are no longer unique. The mysql server does/should not restart often, but this is breaking. Are there any easy ways around this?

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  • Comments on Comments

    - by Joe Mayo
    I almost tweeted a reply to Capar Kleijne's question about comments on Twitter, but realized that my opinion exceeded 140 characters. The following is based upon my experience with extremes and approaches that I find useful in code comments. There are a couple extremes that I've seen and reasons why people go the distance in each approach. The most common extreme is no comments in the code at all.  A few bad reasons why this happens is because a developer is in a hurry, sloppy, or is interested in job preservation. The unfortunate result is that the code is difficult to understand and hard to maintain. The drawbacks to no comments in code are a primary reason why teachers drill the need for commenting code into our heads.  This viewpoint assumes the lack of comments are bad because the code is bad, but there is another reason for not commenting that is gaining more popularity. I've heard/and read that code should be self documenting. Following this thought pattern, if code is well written with meaningful names, there should not be a reason for comments.  An addendum to this argument is that comments are often neglected and get out-of-date, but the code is what is kept up-to-date. Presumably, if code contained very good naming, it would be easy to maintain.  This is a noble perspective and I like the practice of meaningful naming of identifiers. However, I think it's also an extreme approach that doesn't cover important cases.  i.e. If an identifier is named badly (subjective differences in opinion) or not changed appropriately during maintenance, then the badly named identifier is no more useful than a stale comment. These were the two no-comment extremes, so let's look at the too many comments extreme. On a regular basis, I'll see cases where the code is over-commented; not nearly as often as the no-comment scenarios, but still prevalent.  These are examples of where every single line in the code is commented.  These comments make the code harder to read because they get in the way of the algorithm.  In most cases, the comments parrot what each line of code does.  If a developer understands the language, then most statements are immediately intuitive.  i.e. what use is it to say that I'm assigning foo to bar when it's clear what the code is doing. I think that over-commenting code is a waste of time that slows down initial development and maintenance.  Understandably, the developer's intentions are admirable because they've had it beaten into their heads that they must comment. However, I think it's an extreme and prefer a more moderate approach. I don't think the extremes do justice to code because each can make maintenance harder.  No comments on bad code is obviously a problem, but the other two extremes are subtle and require qualification to address properly. The problem I see with the code-as-documentation approach is that it doesn't lift the developer out of the algorithm to identify dependencies, intentions, and hacks. Any developer can read code and follow an algorithm, but they still need to know where it fits into the big picture of the application. Because of indirections with language features like interfaces, delegates, and virtual members, code can become complex.  Occasionally, it's useful to point out a nuance or reason why a piece of code is there. i.e. If you've building an app that communicates via HTTP, you'll have certain headers to include for the endpoint, and it could be useful to point out why the code for setting those header values is there and how they affect the application. An argument against this could be that you should extract that code into a separate method with a meaningful name to describe the scenario.  My problem with such an approach would be that your code base becomes even more difficult to navigate and work with because you have all of this extra code just to make the code more meaningful. My opinion is that a simple and well-stated comment stating the reasons and intention for the code is more natural and convenient to the initial developer and maintainer.  I just don't agree with the approach of going out of the way to avoid making a comment.  I'm also concerned that some developers would take this approach as an excuse to not comment their bad code. Another area where I like comments is on documentation comments.  Java has it and so does C# and VB.  It's convenient because we can build automated tools that extract these comments.  These extracted comments are often much better than no documentation at all.  The "go read the code" answer always doesn't fulfill the need for a quick summary of an API. To summarize, I think that the extremes of no comments and too many comments are less than desirable approaches. I prefer documentation comments to explain each class and member (API level) and code comments as necessary to supplement well-written code. Joe

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