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• Bluetooth DUN Tethering fails

  - by tacone

  I have an HTC Desire HD, with Android Froyo (2.2) and PDANet installed. I am using Ubuntu 10.10. I cannot tether it over Bluetooth either with Network Manager or BlueMan. (note, I installed Blueman only after failing with NetWork manager, and I even tried the last version from the PPA). With both my device is discovered, paired, setup. But connecting always fail. Network manager says it cannot get the details of my device Blueman says Connection Refused (111) Here are some relevant entries from syslog. Mar 11 22:13:00 tacone-macbook bluetoothd[2242]: Bluetooth deamon 4.69 Mar 11 22:13:00 tacone-macbook bluetoothd[2243]: Starting SDP server Mar 11 22:13:00 tacone-macbook bluetoothd[2243]: Starting experimental netlink support Mar 11 22:13:00 tacone-macbook bluetoothd[2243]: Failed to find Bluetooth netlink family Mar 11 22:13:00 tacone-macbook bluetoothd[2243]: Failed to init netlink plugin Mar 11 22:13:00 tacone-macbook kernel: [ 158.284357] Bluetooth: L2CAP ver 2.14 Mar 11 22:13:00 tacone-macbook kernel: [ 158.284361] Bluetooth: L2CAP socket layer initialized Mar 11 22:13:00 tacone-macbook kernel: [ 158.446781] Bluetooth: BNEP (Ethernet Emulation) ver 1.3 Mar 11 22:13:00 tacone-macbook kernel: [ 158.446784] Bluetooth: BNEP filters: protocol multicast Mar 11 22:13:00 tacone-macbook bluetoothd[2243]: HCI dev 0 registered Mar 11 22:13:00 tacone-macbook kernel: [ 158.569481] Bluetooth: SCO (Voice Link) ver 0.6 Mar 11 22:13:00 tacone-macbook kernel: [ 158.569484] Bluetooth: SCO socket layer initialized Mar 11 22:13:00 tacone-macbook bluetoothd[2243]: HCI dev 0 up Mar 11 22:13:00 tacone-macbook bluetoothd[2243]: Starting security manager 0 Mar 11 22:13:00 tacone-macbook bluetoothd[2243]: ioctl(HCIUNBLOCKADDR): Invalid argument (22) Mar 11 22:13:00 tacone-macbook kernel: [ 158.818600] Bluetooth: RFCOMM TTY layer initialized Mar 11 22:13:00 tacone-macbook kernel: [ 158.818607] Bluetooth: RFCOMM socket layer initialized Mar 11 22:13:00 tacone-macbook kernel: [ 158.818610] Bluetooth: RFCOMM ver 1.11 Mar 11 22:13:00 tacone-macbook bluetoothd[2243]: probe failed with driver input-headset for device /org/bluez/2242/hci0/dev_F8_DB_7F_AF_6B_EE Mar 11 22:13:00 tacone-macbook bluetoothd[2243]: Adapter /org/bluez/2242/hci0 has been enabled Mar 11 22:13:00 tacone-macbook pulseaudio[1757]: bluetooth-util.c: Error from ListDevices reply: org.freedesktop.DBus.Error.AccessDenied Mar 11 22:13:00 tacone-macbook NetworkManager[1247]: <warn> bluez error getting adapter properties: Rejected send message, 1 matched rules; type="method_call", sender=":1.4" (uid=0 pid=1247 comm="NetworkManager) interface="org.bluez.Adapter" member="GetProperties" error name="(unset)" requested_reply=0 destination="org.bluez" (uid=0 pid=2242 comm="/usr/sbin/bluetoothd)) Mar 11 22:13:00 tacone-macbook bluetoothd[2243]: return_link_keys (sba=00:23:6C:B5:03:6F, dba=00:23:6C:C0:F1:B0) Mar 11 22:13:00 tacone-macbook pulseaudio[1757]: bluetooth-util.c: Error from GetProperties reply: org.freedesktop.DBus.Error.AccessDenied Mar 11 22:15:02 tacone-macbook bluetoothd[2243]: Discovery session 0x2262d7c0 with :1.45 activated Mar 11 22:15:15 tacone-macbook bluetoothd[2243]: Stopping discovery Mar 11 22:15:15 tacone-macbook pulseaudio[1757]: bluetooth-util.c: Error from GetProperties reply: org.freedesktop.DBus.Error.AccessDenied Mar 11 22:15:16 tacone-macbook bluetoothd[2243]: link_key_request (sba=00:23:6C:B5:03:6F, dba=F8:DB:7F:AF:6B:EE) Mar 11 22:15:16 tacone-macbook bluetoothd[2243]: io_capa_request (sba=00:23:6C:B5:03:6F, dba=F8:DB:7F:AF:6B:EE) Mar 11 22:15:17 tacone-macbook bluetoothd[2243]: io_capa_response (sba=00:23:6C:B5:03:6F, dba=F8:DB:7F:AF:6B:EE) Mar 11 22:15:18 tacone-macbook bluetoothd[2243]: Stopping discovery Mar 11 22:15:28 tacone-macbook bluetoothd[2243]: link_key_notify (sba=00:23:6C:B5:03:6F, dba=F8:DB:7F:AF:6B:EE, type=5) Mar 11 22:15:28 tacone-macbook kernel: [ 306.585725] l2cap_recv_acldata: Unexpected continuation frame (len 0) Mar 11 22:15:28 tacone-macbook kernel: [ 306.630757] l2cap_recv_acldata: Unexpected continuation frame (len 0) Mar 11 22:15:28 tacone-macbook bluetoothd[2243]: Authentication requested Mar 11 22:15:28 tacone-macbook bluetoothd[2243]: link_key_request (sba=00:23:6C:B5:03:6F, dba=F8:DB:7F:AF:6B:EE) Mar 11 22:15:28 tacone-macbook kernel: [ 306.784829] l2cap_recv_acldata: Unexpected continuation frame (len 0) Mar 11 22:15:28 tacone-macbook kernel: [ 306.857861] l2cap_recv_acldata: Unexpected continuation frame (len 0) Mar 11 22:15:29 tacone-macbook bluetoothd[2243]: probe failed with driver input-headset for device /org/bluez/2242/hci0/dev_F8_DB_7F_AF_6B_EE Mar 11 22:15:29 tacone-macbook pulseaudio[1757]: bluetooth-util.c: Error from GetProperties reply: org.freedesktop.DBus.Error.AccessDenied Mar 11 22:15:29 tacone-macbook pulseaudio[1757]: last message repeated 8 times Mar 11 22:15:29 tacone-macbook bluetoothd[2243]: Stopping discovery Mar 11 22:15:30 tacone-macbook modem-manager: (tty/rfcomm0): could not get port's parent device Mar 11 22:15:30 tacone-macbook modem-manager: (rfcomm0) opening serial device... Mar 11 22:15:30 tacone-macbook modem-manager: (rfcomm0): probe requested by plugin 'Generic' Mar 11 22:15:43 tacone-macbook modem-manager: (rfcomm0) closing serial device... Mar 11 22:15:43 tacone-macbook modem-manager: (rfcomm0) opening serial device... Mar 11 22:15:49 tacone-macbook modem-manager: (rfcomm0) closing serial device... Mar 11 22:16:15 tacone-macbook modem-manager: (tty/rfcomm0): could not get port's parent device Mar 11 22:16:19 tacone-macbook kernel: [ 357.375108] l2cap_recv_acldata: Unexpected continuation frame (len 0) Mar 11 22:16:24 tacone-macbook bluetoothd[2243]: link_key_request (sba=00:23:6C:B5:03:6F, dba=F8:DB:7F:AF:6B:EE) Mar 11 22:16:24 tacone-macbook kernel: [ 362.169506] l2cap_recv_acldata: Unexpected continuation frame (len 0) Mar 11 22:16:24 tacone-macbook kernel: [ 362.215529] l2cap_recv_acldata: Unexpected continuation frame (len 0) Mar 11 22:16:24 tacone-macbook bluetoothd[2243]: link_key_request (sba=00:23:6C:B5:03:6F, dba=F8:DB:7F:AF:6B:EE) Mar 11 22:16:24 tacone-macbook kernel: [ 362.281559] l2cap_recv_acldata: Unexpected continuation frame (len 0) Mar 11 22:16:24 tacone-macbook kernel: [ 362.330588] l2cap_recv_acldata: Unexpected continuation frame (len 0) Mar 11 22:16:24 tacone-macbook modem-manager: (tty/rfcomm0): could not get port's parent device Any help ? PS: tethering via USB or WiFi is not an option, I need to do it over Bluetooth.

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• ODI and OBIEE 11g Integration

  - by David Allan

  Here we will see some of the connectivity options to OBIEE 11g using the JDBC driver. You’ll see based upon some connection properties how the physical or presentation layers can be utilized. In the integrators guide for OBIEE 11g you will find a brief statement indicating that there actually is a JDBC driver for OBIEE. In OBIEE 11g its now possible to connect directly to the physical layer, Venkat has an informative post here on this topic. In ODI 11g the Oracle BI technology is shipped with the product along with KMs for reverse engineering, and using OBIEE models for a data source. When you install OBIEE in 11g a light weight demonstration application is preinstalled in the server, when you open this in the BI Administration tool we see the regular 3 panel view within the administration tool. To interrogate this system via JDBC (just like ODI does using the KMs) need a couple of things; the JDBC driver from OBIEE 11g, a java client program and the credentials. In my java client program I want to connect to the OBIEE system, when I connect I can interrogate what the JDBC driver presents for the metadata. The metadata projected via the JDBC connection’s DatabaseMetadata changes depending on whether the property NQ_SESSION.SELECTPHYSICAL is set when the java client connects. Let’s use the sample app to illustrate. I have a java client program here that will print out the tables in the DatabaseMetadata, it will also output the catalog and schema. For example if I execute without any special JDBC properties as follows; java -classpath .;%BIHOMEDIR%\clients\bijdbc.jar meta_jdbc oracle.bi.jdbc.AnaJdbcDriver jdbc:oraclebi://localhost:9703/ weblogic mypass Then I get the following returned representing the presentation layer, the sample I used is XML, and has no schema; Catalog Schema Table Sample Sales Lite null Base Facts Sample Sales Lite null Calculated Facts …     Sample Targets Lite null Base Facts …     Now if I execute with the only difference being the JDBC property NQ_SESSION.SELECTPHYSICAL with the value Yes, then I see a different set of values representing the physical layer in OBIEE; java -classpath .;%BIHOMEDIR%\clients\bijdbc.jar meta_jdbc oracle.bi.jdbc.AnaJdbcDriver jdbc:oraclebi://localhost:9703/ weblogic mypass NQ_SESSION.SELECTPHYSICAL=Yes The following is returned; Catalog Schema Table Sample App Lite Data null D01 Time Day Grain Sample App Lite Data null F10 Revenue Facts (Order grain) …     System DB (Update me)     …     If this was a database system such as Oracle, the catalog value would be the OBIEE database name and the schema would be the Oracle database schema. Other systems which have real catalog structure such as SQLServer would use its catalog value. Its this ‘Catalog’ and ‘Schema’ value that is important when integration OBIEE with ODI. For the demonstration application in OBIEE 11g, the following illustration shows how the information from OBIEE is related via the JDBC driver through to ODI. In the XML example above, within ODI’s physical schema definition on the right, we leave the schema blank since the XML data source has no schema. When I did this at first, I left the default value that ODI places in the Schema field since which was ‘<Undefined>’ (like image below) but this string is actually used in the RKM so ended up not finding any tables in this schema! Entering an empty string resolved this. Below we see a regular Oracle database example that has the database, schema, physical table structure, and how this is defined in ODI.   Remember back to the physical versus presentation layer usage when we passed the special property, well to do this in ODI, the data server has a panel for properties where you can define key/value pairs. So if you want to select physical objects from the OBIEE server, then you must set this property. An additional changed in ODI 11g is the OBIEE connection pool support, this has been implemented via a ‘Connection Pool’ flex field for the Oracle BI data server. So here you set the connection pool name from the OBIEE system that you specifically want to use and this is used by the Oracle BI to Oracle (DBLINK) LKM, so if you are using this you must set this flex field. Hopefully a useful insight into some of the mechanics of how this hangs together.

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• Getting WCF Services in a Silverlight solution to play nice on deployment

  - by brendonpage

  I have come across 2 issues with deploying WCF services in a Silverlight solution, admittedly the one is more of a hiccup, and only occurs if you take the easy way out and reference your services through visual studio. The First Issue This occurs when you deploy your WFC services to an IIS server. When browse to the services using your web browser, you are greeted with “This collection already contains an address with scheme http.  There can be at most one address per scheme in this collection.”. When you make a call to this service from your Silverlight application, you get the extremely helpful “NotFound” error, this error message can be found in the error property of the event arguments on the complete event handler for that call. As it did with me this will leave most people scratching their head, because the very same services work just fine on the ASP.NET Development Web Server and on my local IIS server. Now I’m no server/hosting/IIS expert so I did a bit of searching when I first encountered this issue. I found out this happens because IIS supports multiple address bindings per protocol (http/https/ftp … etc) per web site, but WCF only supports binding to one address per protocol. This causes a problem when the WCF service is hosted on a site with multiple address bindings, because IIS provides all of the bindings to the host factory when running the service. While this problem occurs mainly on shared hosting solutions, it is not limited to shared hosting, it just seems like all shared hosting providers setup sites on their servers with multiple address bindings. For interests sake I added functionality to the example project attached to this post to dump the addresses given to the WCF service by IIS into a log file. This was the output on the shared hosting solution I use: http://mydomain.co.za/Services/TestService.svc http://www.mydomain.co.za/Services/TestService.svc http://mydomain-co-za.win13.wadns.net/Services/TestService.svc http://win13/Services/TestService.svc As you can see all these addresses are for the http protocol, which is where it all goes wrong for WCF. Fixes for the First Issue There are a few ways to get around this. The first being the easiest, target .NET 4! Yes that's right in .NET 4 WCF services support multiple addresses per protocol. This functionality is enabled by an option, which is on by default if you create a new project, you will need to turn on if you are upgrading to .NET 4. To do this set the multipleSiteBindingsEnabled property of the serviceHostingEnviroment tag in the web.config file to true, as shown below: <system.serviceModel>     <serviceHostingEnvironment multipleSiteBindingsEnabled="true" /> </system.serviceModel> Beware this ONLY works in .NET 4, so if you don’t have a server with .NET 4 installed on that you can deploy to, you will need to employ one of the other work a rounds. The second option will work for .NET 3.5 & 4. For this option all you need to do is modify the web.config file and add baseAddressPrefixFilters to the serviceHostingEnviroment tag as shown below: <system.serviceModel>     <serviceHostingEnvironment>         <baseAddressPrefixFilters>              <add prefix="http://www.mydomain.co.za"/>         </baseAddressPrefixFilters>     </serviceHostingEnvironment> </system.serviceModel> These will be used to filter the list of base addresses that IIS provides to the host factory. When specifying these prefix filters be sure to specify filters which will only allow 1 result through, otherwise the entire exercise will be pointless. There is however a problem with this work a round, you are only allowed to specify 1 prefix filter per protocol. Which means you can’t add filters for all your environments, this will therefore add to the list of things to do before deploying or switching dev machines. The third option is the one I currently employ, it will work for .NET 3, 3.5 & 4, although it is not needed for .NET 4. For this option you create a custom host factory which inherits from the ServiceHostFactory class. In the implementation of the ServiceHostFactory you employ logic to figure out which of the base addresses, that are give by IIS, to use when creating the service host. The logic you use to do this is completely up to you, I have seen quite a few solutions that simply statically reference an index from the list of base addresses, this works for most situations but falls short in others. For instance, if the order of the base addresses where to change, it might end up returning an address that only resolves on the servers local network, like the last one in the example I gave at the beginning. Another instance, if a request comes in on a different protocol, like https, you will be creating the service host using an address which is on the incorrect protocol, like http. To reliably find the correct address to use, I use the address that the service was requested on. To accomplish this I use the HttpContext, which requires the service to operate with AspNetCompatibilityRequirements set on. If for some reason running you services with AspNetCompatibilityRequirements on isn’t an option, you can still use this method, you will just have to come up with your own logic for selecting the correct address. First you will need to enable AspNetCompatibilityRequirements for your hosting environment, to do this you will need to set it to true in the web.config file as shown below: <system.serviceModel>     <serviceHostingEnvironment AspNetCompatibilityRequirements="true" /> </system.serviceModel> You will then need to mark any services that are going to use the custom host factory, to allow AspNetCompatibilityRequirements, as shown below: [AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)] public class TestService { } Now for the custom host factory, this is where the logic lives that selects the correct address to create service host with. The one i use is shown below: public class CustomHostFactory : ServiceHostFactory { protected override ServiceHost CreateServiceHost(Type serviceType, Uri[] baseAddresses) { // // Compose a prefix filter based on the requested uri // string prefixFilter = HttpContext.Current.Request.Url.Scheme + "://" + HttpContext.Current.Request.Url.DnsSafeHost; if (!HttpContext.Current.Request.Url.IsDefaultPort) { prefixFilter += ":" + HttpContext.Current.Request.Url.Port.ToString() + "/"; } // // Find a base address that matches the prefix filter // foreach (Uri baseAddress in baseAddresses) { if (baseAddress.OriginalString.StartsWith(prefixFilter)) { return new ServiceHost(serviceType, baseAddress); } } // // Throw exception if no matching base address was found // throw new Exception("Custom Host Factory: No base address matching '" + prefixFilter + "' was found."); } } The most important line in the custom host factory is the one that returns a new service host. This has to return a service host that specifies only one base address per protocol. Since I filter by the address the request came on in, I only need to create the service host with one address, since this address will always be of the correct protocol. Now you have a custom host factory you have to tell your services to use it. To do this you view the markup of the service by right clicking on it in the solution explorer and choosing “View Markup”. Then you add/set the value of the Factory property to the full namespace path of you custom host factory, as shown below. And that is it done, the service will now use the specified custom host factory. The Second Issue As I mentioned earlier this issue is more of a hiccup, but I thought worthy of a mention so I included it. This issue only occurs when you add a service reference to a Silverlight project. Visual Studio will generate a lot of code for you, part of that generated code is the ServiceReferences.ClientConfig file. This file stores the endpoint configuration that is used when accessing your services using the generated proxy classes. Here is what that file looks like: <configuration>     <system.serviceModel>         <bindings>             <customBinding>                 <binding name="CustomBinding_TestService">                     <binaryMessageEncoding />                     <httpTransport maxReceivedMessageSize="2147483647" maxBufferSize="2147483647" />                 </binding>                 <binding name="CustomBinding_BrokenService">                     <binaryMessageEncoding />                     <httpTransport maxReceivedMessageSize="2147483647" maxBufferSize="2147483647" />                 </binding>             </customBinding>         </bindings>         <client>             <endpoint address="http://localhost:49347/services/TestService.svc"                 binding="customBinding" bindingConfiguration="CustomBinding_TestService"                 contract="TestService.TestService" name="CustomBinding_TestService" />             <endpoint address="http://localhost:49347/Services/BrokenService.svc"                 binding="customBinding" bindingConfiguration="CustomBinding_BrokenService"                 contract="BrokenService.BrokenService" name="CustomBinding_BrokenService" />         </client>     </system.serviceModel> </configuration> As you will notice the addresses for the end points are set to the addresses of the services you added the service references from, so unless you are adding the service references from your live services, you will have to change these addresses before you deploy. This is little more than an annoyance really, but it adds to the list of things to do before you can deploy, and if left unchecked that list can get out of control. Fix for the Second Issue The way you would usually access a service added this way is to create an instance of the proxy class like so: BrokenServiceClient proxy = new BrokenServiceClient(); Closer inspection of these generated proxy classes reveals that there are a few overloaded constructors, one of which allows you to specify the end point address to use when creating the proxy. From here all you have to do is come up with some logic that will provide you with the relative path to your services. Since my WCF services are usually hosted in the same project as my Silverlight app I use the class shown below: public class ServiceProxyHelper { /// <summary> /// Create a broken service proxy /// </summary> /// <returns>A broken service proxy</returns> public static BrokenServiceClient CreateBrokenServiceProxy() { Uri address = new Uri(Application.Current.Host.Source, "../Services/BrokenService.svc"); return new BrokenServiceClient("CustomBinding_BrokenService", address.AbsoluteUri); } } Then I will create an instance of the proxy class using my service helper class like so: BrokenServiceClient proxy = ServiceProxyHelper.CreateBrokenServiceProxy(); The way this works is “Application.Current.Host.Source” will return the URL to the ClientBin folder the Silverlight app is hosted in, the “../Services/BrokenService.svc” is then used as the relative path to the service from the ClientBin folder, combined by the Uri object this gives me the URL to my service. The “CustomBinding_BrokenService” is a reference to the end point configuration in the ServiceReferences.ClientConfig file. Yes this means you still need the ServiceReferences.ClientConfig file. All this is doing is using a different end point address than the one specified in the ServiceReferences.ClientConfig file, all the other settings form the ServiceReferences.ClientConfig file are still used when creating the proxy. I have uploaded an example project which covers the custom host factory solution from the first issue and everything from the second issue. I included the code to write a list of base addresses to a log file in my implementation of the custom host factory, this is not need for the custom host factory to function and can safely be removed. Download (WCFServicesDeploymentExample.zip)

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• What does (Lua) game scripting mean?

  - by Gerenuk

  I've read that Lua is often used for embedded scripting and in particular game for scripting. I find it hard to picture how it is used exactly. Can you describe why and for which features and for which audience it is used? This questions isn't specifically addressing Lua, but rather any embedded scripting that serves a purpose similar to Lua scripting. Is it used for end-users to make custom adjustments? Is it used for game developers to speed up creation of game logic (levels, AI, ...)? Is it used to script game framework code since scripting can be faster? Basically I'm wondering how deep between plain configuration and framework logic such scripting usage goes. And how much scripting is done. A few configuration lines or a considerable amount?

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• Question about how to use strong typed dataset in N-tier application for .NET

  - by sb

  Hello All, I need some expert advice on strong typed data sets in ADO.NET that are generated by the Visual Studio. Here are the details. Thank you in advance. I want to write a N-tier application where Presentation layer is in C#/windows forms, Business Layer is a Web service and Data Access Layer is SQL db. So, I used Visual Studio 2005 for this and created 3 projects in a solution. project 1 is the Data access layer. In this I have used visual studio data set generator to create a strong typed data set and table adapter (to test I created this on the customers table in northwind). The data set is called NorthWindDataSet and the table inside is CustomersTable. project 2 has the web service which exposes only 1 method which is GetCustomersDataSet. This uses the project1 library's table adapter to fill the data set and return it to the caller. To be able to use the NorthWindDataSet and table adapter, I added a reference to the project 1. project 3 is a win forms app and this uses the web service as a reference and calls that service to get the data set. In the process of building this application, in the PL, I added a reference to the DataSet generated above in the project 1 and in form's load I call the web service and assign the received DataSet from the web service to this dataset. But I get the error: "Cannot implicitly convert type 'PL.WebServiceLayerReference.NorthwindDataSet' to 'BL.NorthwindDataSet' e:\My Documents\Visual Studio 2008\Projects\DataSetWebServiceExample\PL\Form1.cs". Both the data sets are same but because I added references from different locations, I am getting the above error I think. So, what I did was I added a reference to project 1 (which defines the data set) to project 3 (the UI) and used the web service to get the DataSet and assing to the right type, now when the project 3 (which has the web form) runs, I get the below runtime exception. "System.InvalidOperationException: There is an error in XML document (1, 5058). --- System.Xml.Schema.XmlSchemaException: Multiple definition of element 'http://tempuri.org/NorthwindDataSet.xsd:Customers' causes the content model to become ambiguous. A content model must be formed such that during validation of an element information item sequence, the particle contained directly, indirectly or implicitly therein with which to attempt to validate each item in the sequence in turn can be uniquely determined without examining the content or attributes of that item, and without any information about the items in the remainder of the sequence." I think this might be because of some cross referenceing errors. My question is, is there a way to use the visual studio generated DataSets in such a way that I can use the same DataSet in all layers (for reuse) but separate the Table Adapter logic to the Data Access Layer so that the front end is abstracted from all this by the web service? If I have hand write the code I loose the goodness the data set generator gives and also if there are columns added later I need to add it by hand etc so I want to use the visual studio wizard as much as possible. thanks for any help on this. sb

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• Unit testing is… well, flawed.

  - by Dewald Galjaard

  Hey someone had to say it. I clearly recall my first IT job. I was appointed Systems Co-coordinator for a leading South African retailer at store level. Don’t get me wrong, there is absolutely nothing wrong with an honest day’s labor and in fact I highly recommend it, however I’m obliged to refer to the designation cautiously; in reality all I had to do was monitor in-store prices and two UNIX front line controllers. If anything went wrong – I only had to phone it in… Luckily that wasn’t all I did. My duties extended to some other interesting annual occurrence – stock take. Despite a bit more curious affair, it was still a tedious process that took weeks of preparation and several nights to complete.  Then also I remember that no matter how elaborate our planning was, the entire exercise would be rendered useless if we couldn’t get the basics right – that being the act of counting. Sounds simple right? We’ll with a store which could potentially carry over tens of thousands of different items… we’ll let’s just say I believe that’s when I first became a coffee addict. In those days the act of counting stock was a very humble process. Nothing like we have today. A staff member would be assigned a bin or shelve filled with items he or she had to sort then count. Thereafter they had to record their findings on a complementary piece of paper. Every night I would manage several teams. Each team was divided into two groups - counters and auditors. Both groups had the same task, only auditors followed shortly on the heels of the counters, recounting stock levels, making sure the original count correspond to their findings. It was a simple yet hugely responsible orchestration of people and thankfully there was one fundamental and golden rule I could always abide by to ensure things run smoothly – No-one was allowed to audit their own work. Nope, not even on nights when I didn’t have enough staff available. This meant I too at times had to get up there and get counting, or have the audit stand over until the next evening. The reason for this was obvious - late at night and with so much to do we were prone to make some mistakes, then on the recount, without a fresh set of eyes, you were likely to repeat the offence. Now years later this rule or guideline still holds true as we develop software (as far removed as software development from counting stock may be). For some reason it is a fundamental guideline we’re simply ignorant of. We write our code, we write our tests and thus commit the same horrendous offence. Yes, the procedure of writing unit tests as practiced in most development houses today – is flawed. Most if not all of the tests we write today exercise application logic – our logic. They are based on the way we believe an application or method should/may/will behave or function. As we write our tests, our unit tests mirror our best understanding of the inner workings of our application code. Unfortunately these tests will therefore also include (or be unaware of) any imperfections and errors on our part. If your logic is flawed as you write your initial code, chances are, without a fresh set of eyes, you will commit the same error second time around too. Not even experience seems to be a suitable solution. It certainly helps to have deeper insight, but is that really the answer we should be looking for? Is that really failsafe? What about code review? Code review is certainly an answer. You could have one developer coding away and another (or team) making sure the logic is sound. The practice however has its obvious drawbacks. Firstly and mainly it is resource intensive and from what I’ve seen in most development houses, given heavy deadlines, this guideline is seldom adhered to. Hardly ever do we have the resources, money or time readily available. So what other options are out there? A quest to find some solution revealed a project by Microsoft Research called PEX. PEX is a framework which creates several test scenarios for each method or class you write, automatically. Think of it as your own personal auditor. Within a few clicks the framework will auto generate several unit tests for a given class or method and save them to a single project. PEX help to audit your work. It lends a fresh set of eyes to any project you’re working on and best of all; it is cost effective and fast. Check them out at http://research.microsoft.com/en-us/projects/pex/ In upcoming posts we’ll dive deeper into how it works and how it can help you.   Certainly there are more similar frameworks out there and I would love to hear from you. Please share your experiences and insights.

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• Any Good Cocos2d Pause Menu Library

  - by Mahbubur R Aaman

  Background : From http://code.google.com/p/cocos2d-iphone/issues/detail?id=173 Scenes/Nodes doesn't support the CocosNodeOpacity protocol. From http://playsnackgames.com/blog/2011/09/cocos2d-tutorial-creating-a-reusable-pause-layer/ Cocos2d offers a simple method to pause and resume itself, but these methods stop the CCDirector (the class that manages most aspects of a Cocos2d’s app lifetime) from running actions and lower the fps to 5 to conserve battery life. Related issues http://www.cocos2d-iphone.org/forum/topic/4368 http://www.cocos2d-iphone.org/forum/topic/151 http://stackoverflow.com/questions/5852354/cocos2d-engine-pause-resume http://stackoverflow.com/questions/11878450/how-to-pause-a-layer-in-cocos2d-2-0 Question : Is there any Good Cocos2d Pause Menu Library solving these tricky issues? This will save many hours of Game Developer's life.

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• DevExpress XAF, Behavior Driven Development (BDD), Domain Driven Development (DDD) and more&ndash;Introduction

  - by Patrick Liekhus

  OK.  I admit it.  I have been horrible at this blogging thing.  However, I have made a commitment to get better at it so here goes.  I have many crazy ideas when it comes to coding and how to make my processes better and now is the time to get them down on paper and get your feedback.  Now, these ideas might not be nearly as wild and crazy as Charlie Sheen, but at least they help me get through my coding assignments. So let’s start by laying out the vision and objectives of this exercise.  I have been trying to come up with the best set of tools, tips and practices so I can get a small team to be as productive as possible without burning out my resources.  My thoughts tend to lean towards the coding practices first as this is what I have been doing for years.  However, as one looks at the process as a whole, we need to remember to keep the users in mind.  If we don’t have a user to accept our application, do we really have an application in the first place? I have been using a commercial framework from DevExpress called eXpress Application Framework (XAF) with their eXpress Persistent Objects (XPO) behind the scenes for a few years.  We have had tremendous success with it and even implemented a code generation layer to save us some time.  Now we want more!!! My goals here are to create a technical stack that employs as many UI’s as possible, while being true to the layers and documenting the process along the way.  I will continue to have a series of these posts that will walk through each step as I work on it.  Right now here is what I have planned: Defining the solution SCRUM/Agile Story Planning Overview of Architectural Plan Feature Driven Development Domain Driven Development Persistence Layer with XPO Windows UI with XAF/XPO Web UI with XAF/XPO OData Services Layer Windows Mobile UI Android UI iPhone UI Blackberry UI Excel UI Outlook UI Lessons Learned I will explain the solution that I plan to implement in the next post.  Thanks again and let me know what you think.

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• Visualize flowchart diagram with multiple end symbols

  - by platzhirsch

  I am looking for a standardize way to visualize the following hierarchical logic: The state of the thread is represented by the answers to the hierarchical set of question You can read this listing like a flowchart, you iterate over the questions decide, go one step deeper and so on. Therefore I thought the best way to visualize it, using a flowchart. The problem is, in this hierarchical set it is possible to end in more than one state and its totally valid. I have never seen a flowchart where you can enter more than one state. Is it still possible and I am missing the right symbol to present this logic or are flowchart not fitting anyway? What other graphical representation could I use, is there something fitting in UML? A non-deterministic state machine seems not to be intuitive enough, transfering it into a deterministic state machine would result in to many states, and so on.

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• Investigation: Can different combinations of components effect Dataflow performance?

  - by jamiet

  Introduction The Dataflow task is one of the core components (if not the core component) of SQL Server Integration Services (SSIS) and often the most misunderstood. This is not surprising, its an incredibly complicated beast and we’re abstracted away from that complexity via some boxes that go yellow red or green and that have some lines drawn between them. Example dataflow In this blog post I intend to look under that facade and get into some of the nuts and bolts of the Dataflow Task by investigating how the decisions we make when building our packages can affect performance. I will do this by comparing the performance of three dataflows that all have the same input, all produce the same output, but which all operate slightly differently by way of having different transformation components. I also want to use this blog post to challenge a common held opinion that I see perpetuated over and over again on the SSIS forum. That is, that people assume adding components to a dataflow will be detrimental to overall performance. Its not surprising that people think this –it is intuitive to think that more components means more work- however this is not a view that I share. I have always been of the opinion that there are many factors affecting dataflow duration and the number of components is actually one of the less important ones; having said that I have never proven that assertion and that is one reason for this investigation. I have actually seen evidence that some people think dataflow duration is simply a function of number of rows and number of components. I’ll happily call that one out as a myth even without any investigation!  The Setup I have a 2GB datafile which is a list of 4731904 (~4.7million) customer records with various attributes against them and it contains 2 columns that I am going to use for categorisation: [YearlyIncome] [BirthDate] The data file is a SSIS raw format file which I chose to use because it is the quickest way of getting data into a dataflow and given that I am testing the transformations, not the source or destination adapters, I want to minimise external influences as much as possible. In the test I will split the customers according to month of birth (12 of those) and whether or not their yearly income is above or below 50000 (2 of those); in other words I will be splitting them into 24 discrete categories and in order to do it I shall be using different combinations of SSIS’ Conditional Split and Derived Column transformation components. The 24 datapaths that occur will each input to a rowcount component, again because this is the least resource intensive means of terminating a datapath. The test is being carried out on a Dell XPS Studio laptop with a quad core (8 logical Procs) Intel Core i7 at 1.73GHz and Samsung SSD hard drive. Its running SQL Server 2008 R2 on Windows 7. The Variables Here are the three combinations of components that I am going to test:     One Conditional Split - A single Conditional Split component CSPL Split by Month of Birth and income category that will use expressions on [YearlyIncome] & [BirthDate] to send each row to one of 24 outputs. This next screenshot displays the expression logic in use: Derived Column & Conditional Split - A Derived Column component DER Income Category that adds a new column [IncomeCategory] which will contain one of two possible text values {“LessThan50000”,”GreaterThan50000”} and uses [YearlyIncome] to determine which value each row should get. A Conditional Split component CSPL Split by Month of Birth and Income Category then uses that new column in conjunction with [BirthDate] to determine which of the same 24 outputs to send each row to. Put more simply, I am separating the Conditional Split of #1 into a Derived Column and a Conditional Split. The next screenshots display the expression logic in use: DER Income Category         CSPL Split by Month of Birth and Income Category       Three Conditional Splits - A Conditional Split component that produces two outputs based on [YearlyIncome], one for each Income Category. Each of those outputs will go to a further Conditional Split that splits the input into 12 outputs, one for each month of birth (identical logic in each). In this case then I am separating the single Conditional Split of #1 into three Conditional Split components. The next screenshots display the expression logic in use: CSPL Split by Income Category         CSPL Split by Month of Birth 1& 2       Each of these combinations will provide an input to one of the 24 rowcount components, just the same as before. For illustration here is a screenshot of the dataflow containing three Conditional Split components: As you can these dataflows have a fair bit of work to do and remember that they’re doing that work for 4.7million rows. I will execute each dataflow 10 times and use the average for comparison. I foresee three possible outcomes: The dataflow containing just one Conditional Split (i.e. #1) will be quicker There is no significant difference between any of them One of the two dataflows containing multiple transformation components will be quicker Regardless of which of those outcomes come to pass we will have learnt something and that makes this an interesting test to carry out. Note that I will be executing the dataflows using dtexec.exe rather than hitting F5 within BIDS. The Results and Analysis The table below shows all of the executions, 10 for each dataflow. It also shows the average for each along with a standard deviation. All durations are in seconds. I’m pasting a screenshot because I frankly can’t be bothered with the faffing about needed to make a presentable HTML table. It is plain to see from the average that the dataflow containing three conditional splits is significantly faster, the other two taking 43% and 52% longer respectively. This seems strange though, right? Why does the dataflow containing the most components outperform the other two by such a big margin? The answer is actually quite logical when you put some thought into it and I’ll explain that below. Before progressing, a side note. The standard deviation for the “Three Conditional Splits” dataflow is orders of magnitude smaller – indicating that performance for this dataflow can be predicted with much greater confidence too. The Explanation I refer you to the screenshot above that shows how CSPL Split by Month of Birth and salary category in the first dataflow is setup. Observe that there is a case for each combination of Month Of Date and Income Category – 24 in total. These expressions get evaluated in the order that they appear and hence if we assume that Month of Date and Income Category are uniformly distributed in the dataset we can deduce that the expected number of expression evaluations for each row is 12.5 i.e. 1 (the minimum) + 24 (the maximum) divided by 2 = 12.5. Now take a look at the screenshots for the second dataflow. We are doing one expression evaluation in DER Income Category and we have the same 24 cases in CSPL Split by Month of Birth and Income Category as we had before, only the expression differs slightly. In this case then we have 1 + 12.5 = 13.5 expected evaluations for each row – that would account for the slightly longer average execution time for this dataflow. Now onto the third dataflow, the quick one. CSPL Split by Income Category does a maximum of 2 expression evaluations thus the expected number of evaluations per row is 1.5. CSPL Split by Month of Birth 1 & CSPL Split by Month of Birth 2 both have less work to do than the previous Conditional Split components because they only have 12 cases to test for thus the expected number of expression evaluations is 6.5 There are two of them so total expected number of expression evaluations for this dataflow is 6.5 + 6.5 + 1.5 = 14.5. 14.5 is still more than 12.5 & 13.5 though so why is the third dataflow so much quicker? Simple, the conditional expressions in the first two dataflows have two boolean predicates to evaluate – one for Income Category and one for Month of Birth; the expressions in the Conditional Split in the third dataflow however only have one predicate thus they are doing a lot less work. To sum up, the difference in execution times can be attributed to the difference between: MONTH(BirthDate) == 1 && YearlyIncome <= 50000 and MONTH(BirthDate) == 1 In the first two dataflows YearlyIncome <= 50000 gets evaluated an average of 12.5 times for every row whereas in the third dataflow it is evaluated once and once only. Multiply those 11.5 extra operations by 4.7million rows and you get a significant amount of extra CPU cycles – that’s where our duration difference comes from. The Wrap-up The obvious point here is that adding new components to a dataflow isn’t necessarily going to make it go any slower, moreover you may be able to achieve significant improvements by splitting logic over multiple components rather than one. Performance tuning is all about reducing the amount of work that needs to be done and that doesn’t necessarily mean use less components, indeed sometimes you may be able to reduce workload in ways that aren’t immediately obvious as I think I have proven here. Of course there are many variables in play here and your mileage will most definitely vary. I encourage you to download the package and see if you get similar results – let me know in the comments. The package contains all three dataflows plus a fourth dataflow that will create the 2GB raw file for you (you will also need the [AdventureWorksDW2008] sample database from which to source the data); simply disable all dataflows except the one you want to test before executing the package and remember, execute using dtexec, not within BIDS. If you want to explore dataflow performance tuning in more detail then here are some links you might want to check out: Inequality joins, Asynchronous transformations and Lookups Destination Adapter Comparison Don’t turn the dataflow into a cursor SSIS Dataflow – Designing for performance (webinar) Any comments? Let me know! @Jamiet

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• Load and Web Performance Testing using Visual Studio Ultimate 2010-Part 2

  - by Tarun Arora

  Welcome back, in part 1 of Load and Web Performance Testing using Visual Studio 2010 I talked about why Performance Testing the application is important, the test tools available in Visual Studio Ultimate 2010 and various test rig topologies. In this blog post I’ll get into the details of web performance & load tests as well as why it’s important to follow a goal based pattern while performance testing your application. Tools => Options => Test Tools Have you visited the treasures of Visual Studio Menu bar tools => Options => Test Tools lately? The options to enable disable prompts on creating, editing, deleting or running manual/automated tests can be controller from here. The default test project language and default test types created on a new test project creation could be selected/unselected from here. Ever wondered how you can change the default limit of 25 test results, this can again be changed from here. If you record a lot of Web Tests and wish for the web test recorder to start with “that” URL populated, well this again can be specified from here. If you haven’t so far, I would urge you to spend 2 minutes in the test tools options.   Test Menu => Ready Steady Test Action! The Test tools are under the Test Menu in Visual Studio, apart from being able to create a new Test and Test List you can also load an existing vsmdi file. You can also manage your test controllers from here. A solution can have one or more test setting files, but there can only be one active test settings file at any time. Again, this selection can be done from here.  You can open the various test windows from under the windows option from the test menu. If you open the Test view window you will see that you have the option to group the tests by work items, project, test type, etc. You can set these properties by right clicking a test in the test list and choosing properties from the context menu.    So, what is a vsmdi file? vsmdi stands for Visual Studio Test Metadata File. Placed under the Solution Items this file keeps track of the list of unit tests in your solution. If you open the vsmdi file as an xml file you will see a series of Test Links nested with in the list Test List tags along with the Run Configuration tag. When in visual studio you run tests, the IDE looks at the vsmdi file to see what tests need to be run. You also have the option of using the vsmdi file in your team builds to specify which tests need to run as part of the build. Refer here for a walkthrough from a fellow blogger on how to use the vsmdi file in the team builds. Web Performance Test – The Truth! In Visual Studio 2010 “Web Tests” have been renamed to “Web Performance Tests”. Apart from renaming this test type there have been several improvements to this test type in visual studio 2010. I am very active on the MSDN Visual Studio And Load Testing forum and a frequent question from many users is “Do Web Tests support Pages that run JavaScript?” I will start with a little bit of background before answering this question. Web Performance Tests operate at the HTTP Layer, but why? To enable you to generate high loads with a relatively low amount of hardware, Web performance tests are driven at the protocol layer rather than instantiating a browser.The most common source of confusion is that users do not realize Web Performance Tests work at the HTTP layer. The tool adds to that misconception. After all, you record in IE, and when running a Web test you can select which browser to use, and then the result viewer shows the results in a browser window. So that means the tests run through the browser, right? NO! The Web test engine works at the HTTP layer, and does not instantiate a browser. What does that mean? In the diagram below, you can see there are no browsers running when the engine is sending and receiving requests. Does that mean I can’t test pages that use Java script? The best example for java script generating HTTP traffic is AJAX calls. The most common example of browser plugins are Silverlight or Flash. The Web test recorder will record HTTP traffic from AJAX calls and from most (but not all) browser plugins. This means you will still be able to web performance test pages that use java script or plugin and play back the results but the playback engine will not show the java script or plug in results in the ‘browser control’. If you want to test the page behaviour as a result of the java script or plug in consider using Coded UI Tests. This page looks like it failed, when in fact it succeeded! Looking closely at the response, and subsequent requests, it is clear the operation succeeded. As stated above, the reason why the browser control is pasting this message is because java script has been disabled in this control. So, to reiterate, the web performance test recorder: - Sends and receives data at the HTTP layer. - Does NOT run a browser. - Does NOT run java script. - Does NOT host ActiveX controls or plugins. There is a great series of blog posts from Ed Glas, i would highly recommend his blog to any one performing Load/Performance testing through Visual Studio. Demo – Web Performance Test [Demo] - Visual Studio Ultimate 2010: Test Settings and Configuration   [Demo]–Visual Studio Ultimate 2010: Web Performance Test   In this short video I try and answer the following questions, Why is performance Testing important? How does Visual Studio Help you performance Test your applications? How do i record a web performance test? How do make a web performance test data driven, transaction driven, loop driven, convert to code, add validations? Best practices for recording Web Performance Tests. I have a web performance test, what next? Creating the Web Performance Test was the first step towards load testing your application. Now that we have the base test we can test the page behaviour when N-users access the page. Have you ever had the head of business call you and mention that the marketing team has done a fantastic job and are expecting increased traffic on the web site, can the website survive the weekend with that additional load? This is the perfect opportunity to capacity test your application to see how your website holds up under various levels of load, you can work the results backwards to see how much hardware you may need to scale up your application to survive the weekend. Apart from that it is always a good idea to have some benchmarks around how the application performs under light loads for short duration, under heavy load for long duration and soak test the application run a constant load for a very week or two to record the effects of constant load for really long durations, this is a great way of identifying how your application handles the default IIS application pool reset which by default is configured to once every 25 hours. These bench marks will act as the perfect yard stick to measure performance gains when you start making improvements. BUT there are some best practices! => Goal Based Load Testing Approach Since the subject is vast and there are a lot of things to measure and analyse, … it is very easy to get distracted from the real goal!  You can optimize your application once you know where the pain points are. There is no point performing a load test of 5000 users if your intranet application will only have a 100 simultaneous users, it is important to keep focussed on the real goals of the project. So the idea is to have a user story around your load testing scenarios and test realistically. So it is recommended that you follow the below outline, It is an Iterative process, refine your objectives, identify the key scenarios, what is the expected workload, key metrics you want to report, record the web performance tests, simulate load and analyse results. Is your application already deployed in Production? This is great! You can analyse the IIS Logs to understand the user behaviour… But what are IIS LOGS? The IIS logs allow you to record events for each application and Web site on the Web server. You can create separate logs for each of your applications and Web sites. Logging information in IIS goes beyond the scope of the event logging or performance monitoring features provided by Windows. The IIS logs can include information, such as who has visited your site, what the visitor viewed, and when the information was last viewed. You can use the IIS logs to identify any attempts to gain unauthorized access to your Web server. How to configure IIS LOGS? For those Ninjas who already have IIS Logs configured (by the way its on by default) and need a way to analyse the IIS Logs, can use the Windows IIS Utility – Log Parser. Log Parser is a very powerful tool that provides a generic SQL-like language on top of many types of data like IIS Logs, Event Viewer entries, XML files, CSV files, File System and others; and it allows you to export the result of the queries to many output formats such as CSV, XML, SQL Server, Charts and others; and it works well with IIS 5, 6, 7 and 7.5. Frequently used Log Parser queries. Demo – Load Test [Demo]–Visual Studio Ultimate 2010: Load Testing   In this short video I try and answer the following questions, - Types of Performance Testing? - Perform Goal driven Load Testing, analyse Test Run Result and Generate a report? Recap A quick recap of what we have covered so far,     Thank you for taking the time out and reading this blog post, in part III of this blog series I’ll be getting into the details of Test Result Analysis, Test Result Drill through, Test Report Generation, Test Run Comparison, and the Asp.net Profiler. If you enjoyed the post, remember to subscribe to http://feeds.feedburner.com/TarunArora. Questions/Feedback/Suggestions, etc please leave a comment. See you on in Part III   Share this post : CodeProject

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• SQL SERVER – Monday Morning Puzzle – Query Returns Results Sometimes but Not Always

  - by pinaldave

  The amount of email I receive sometime it is impossible for me to answer every email. Nonetheless I try to answer pretty much every email I receive. However, quite often I receive such questions in email that I have no answer to them because either emails are not complete or they are out of my domain expertise. In recent times I received one email which had only one or two lines but indeed attracted my attention to it. The question was bit vague but it indeed made me think. The answer was not straightforward so I had to keep on writing the answer as I remember it. However, after writing the answer I do not feel satisfied. Let me put this question in front of you and see if we all can come up with a comprehensive answer. Question: I am beginner with SQL Server. I have one query, it sometime returns a result and sometime it does not return me the result. Where should I start looking for a solution and what kind of information I should send to you so you can help me with solving. I have no clue, please guide me. Well, if you read the question, it is indeed incomplete and it does not contain much of the information at all. I decided to help him and here is the answer, which I started to compose. Answer: As there are not much information in the original question, I am not confident what will solve your problem. However, here are the few things which you can try to look at and see if that solves your problem. Check parameter which is passed to the query. Is the parameter changing at various executions? Check connection string – is there some kind of logic around it? Do you have a non-deterministic component in your query logic? (In other words – does your result is based on current date time or any other time based function?) Are you facing time out while running your query? Is there any error in error log? What is the business logic in your query? Do you have all the valid permissions to all the objects used in the query? Are permissions changing or query accessing a different object in various executions? (Add your suggestions here) Meanwhile, have you ever faced this situation? If yes, do share your experience in the comment area. I will send a copy of my book SQL Server Interview Questions and Answers to one of the most interesting comment. The winner will be announced by next Monday.  Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Interview Questions and Answers, SQL Puzzle, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• Does it make sense to use ORM in Android development?

  - by Heinzi

  Does it make sense to use an ORM in Android development or is the framework optimized for a tighter coupling between the UI and the DB layer? Background: I've just started with Android development, and my first instinct (coming from a .net background) was to look for a small object-relational mapper and other tools that help reduce boilerplate clode (e.g. POJOs + OrmLite + Lombok). However, while developing my first toy application I stumbled upon a UI class that explicitly requires a database cursor: AlphabetIndexer. That made me wonder if maybe the Android library is not suited for a strict decoupling of UI and DB layer and that I will miss out on a lot of useful, time-saving features if I try to use POJOs everywhere (instead of direct database access). Clarification: I'm quite aware of the advantages of using ORM in general, I'm specifically interested in how well the Android class library plays along with it.

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• ROA on top of SOA

  - by Vaibhav Pujari

  I already have a stable Service Oriented Architecture for my application which exposes services as API calls. (the verbs) Now, I need to build a Resource Oriented Architecture to expose a RESTful API to interact with the application objects. (the nouns) What are the best practices to reuse the existing services: - without any persistence inside my new code. - without putting unnecessary logic into the REST layer i.e. it should ideally just leverage the services provided by SOA API. I want this layer to be as thin as possible. - without modifying the existing SOA API - allow easy extension of the REST API i.e. it should be easy to add more resources without changing the (yet to be written) core code. (I want to make resource names and their associated actions configurable so more contributors can easily add resources without a need to understand my module) Any advices/suggestions how to achieve this? Edit: Adding more info My Stack: My existing stacks is in Java. But since I plan to just use the services, I don't think that should affect the design of new REST code. I am planning to implement the new REST code in PHP. How well the services map to resources? Some services are mapped well i.e. there are services for creating, updating application objects. But for other application objects, there are no direct services available. More importantly, there are actions beyond just create, update etc. that apply to application objects. And I would like to provide some way for these actions to be exposed through REST. Since these are verbs, how do I deal with them? Where exactly I need help? I would appreciate any help towards high level design to accomplish the task along-with making the framework extendible. For instance, tomorrow there are some new services added to my SOA layer, I want to make sure it is easy for a fresh developer to write a REST call by simply registering a new resource (in a config file/db) and write code for connecting it with SOA calls. Just like plugin.

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• C#: Why Decorate When You Can Intercept

  - by James Michael Hare

  We've all heard of the old Decorator Design Pattern (here) or used it at one time or another either directly or indirectly.  A decorator is a class that wraps a given abstract class or interface and presents the same (or a superset) public interface but "decorated" with additional functionality.   As a really simplistic example, consider the System.IO.BufferedStream, it itself is a descendent of System.IO.Stream and wraps the given stream with buffering logic while still presenting System.IO.Stream's public interface:   1: Stream buffStream = new BufferedStream(rawStream); Now, let's take a look at a custom-code example.  Let's say that we have a class in our data access layer that retrieves a list of products from a database:  1: // a class that handles our CRUD operations for products 2: public class ProductDao 3: { 4: ... 5:  6: // a method that would retrieve all available products 7: public IEnumerable<Product> GetAvailableProducts() 8: { 9: var results = new List<Product>(); 10:  11: // must create the connection 12: using (var con = _factory.CreateConnection()) 13: { 14: con.ConnectionString = _productsConnectionString; 15: con.Open(); 16:  17: // create the command 18: using (var cmd = _factory.CreateCommand()) 19: { 20: cmd.Connection = con; 21: cmd.CommandText = _getAllProductsStoredProc; 22: cmd.CommandType = CommandType.StoredProcedure; 23:  24: // get a reader and pass back all results 25: using (var reader = cmd.ExecuteReader()) 26: { 27: while(reader.Read()) 28: { 29: results.Add(new Product 30: { 31: Name = reader["product_name"].ToString(), 32: ... 33: }); 34: } 35: } 36: } 37: }            38:  39: return results; 40: } 41: } Yes, you could use EF or any myriad other choices for this sort of thing, but the germaine point is that you have some operation that takes a non-trivial amount of time.  What if, during the production day I notice that my application is performing slowly and I want to see how much of that slowness is in the query versus my code.  Well, I could easily wrap the logic block in a System.Diagnostics.Stopwatch and log the results to log4net or other logging flavor of choice: 1:     // a class that handles our CRUD operations for products 2:     public class ProductDao 3:     { 4:         private static readonly ILog _log = LogManager.GetLogger(typeof(ProductDao)); 5:         ... 6:         7:         // a method that would retrieve all available products 8:         public IEnumerable<Product> GetAvailableProducts() 9:         { 10:             var results = new List<Product>(); 11:             var timer = Stopwatch.StartNew(); 12:             13:             // must create the connection 14:             using (var con = _factory.CreateConnection()) 15:             { 16:                 con.ConnectionString = _productsConnectionString; 17:                 18:                 // and all that other DB code... 19:                 ... 20:             } 21:             22:             timer.Stop(); 23:             24:             if (timer.ElapsedMilliseconds > 5000) 25:             { 26:                 _log.WarnFormat("Long query in GetAvailableProducts() took {0} ms", 27:                     timer.ElapsedMillseconds); 28:             } 29:             30:             return results; 31:         } 32:     } In my eye, this is very ugly.  It violates Single Responsibility Principle (SRP), which says that a class should only ever have one responsibility, where responsibility is often defined as a reason to change.  This class (and in particular this method) has two reasons to change: If the method of retrieving products changes. If the method of logging changes. Well, we could “simplify” this using the Decorator Design Pattern (here).  If we followed the pattern to the letter, we'd need to create a base decorator that implements the DAOs public interface and forwards to the wrapped instance.  So let's assume we break out the ProductDAO interface into IProductDAO using your refactoring tool of choice (Resharper is great for this). Now, ProductDao will implement IProductDao and get rid of all logging logic: 1:     public class ProductDao : IProductDao 2:     { 3:         // this reverts back to original version except for the interface added 4:     } 5:  And we create the base Decorator that also implements the interface and forwards all calls: 1:     public class ProductDaoDecorator : IProductDao 2:     { 3:         private readonly IProductDao _wrappedDao; 4:         5:         // constructor takes the dao to wrap 6:         public ProductDaoDecorator(IProductDao wrappedDao) 7:         { 8:             _wrappedDao = wrappedDao; 9:         } 10:         11:         ... 12:         13:         // and then all methods just forward their calls 14:         public IEnumerable<Product> GetAvailableProducts() 15:         { 16:             return _wrappedDao.GetAvailableProducts(); 17:         } 18:     } This defines our base decorator, then we can create decorators that add items of interest, and for any methods we don't decorate, we'll get the default behavior which just forwards the call to the wrapper in the base decorator: 1:     public class TimedThresholdProductDaoDecorator : ProductDaoDecorator 2:     { 3:         private static readonly ILog _log = LogManager.GetLogger(typeof(TimedThresholdProductDaoDecorator)); 4:         5:         public TimedThresholdProductDaoDecorator(IProductDao wrappedDao) : 6:             base(wrappedDao) 7:         { 8:         } 9:         10:         ... 11:         12:         public IEnumerable<Product> GetAvailableProducts() 13:         { 14:             var timer = Stopwatch.StartNew(); 15:             16:             var results = _wrapped.GetAvailableProducts(); 17:             18:             timer.Stop(); 19:             20:             if (timer.ElapsedMilliseconds > 5000) 21:             { 22:                 _log.WarnFormat("Long query in GetAvailableProducts() took {0} ms", 23:                     timer.ElapsedMillseconds); 24:             } 25:             26:             return results; 27:         } 28:     } Well, it's a bit better.  Now the logging is in its own class, and the database logic is in its own class.  But we've essentially multiplied the number of classes.  We now have 3 classes and one interface!  Now if you want to do that same logging decorating on all your DAOs, imagine the code bloat!  Sure, you can simplify and avoid creating the base decorator, or chuck it all and just inherit directly.  But regardless all of these have the problem of tying the logging logic into the code itself. Enter the Interceptors.  Things like this to me are a perfect example of when it's good to write an Interceptor using your class library of choice.  Sure, you could design your own perfectly generic decorator with delegates and all that, but personally I'm a big fan of Castle's Dynamic Proxy (here) which is actually used by many projects including Moq. What DynamicProxy allows you to do is intercept calls into any object by wrapping it with a proxy on the fly that intercepts the method and allows you to add functionality.  Essentially, the code would now look like this using DynamicProxy: 1: // Note: I like hiding DynamicProxy behind the scenes so users 2: // don't have to explicitly add reference to Castle's libraries. 3: public static class TimeThresholdInterceptor 4: { 5: // Our logging handle 6: private static readonly ILog _log = LogManager.GetLogger(typeof(TimeThresholdInterceptor)); 7:  8: // Handle to Castle's proxy generator 9: private static readonly ProxyGenerator _generator = new ProxyGenerator(); 10:  11: // generic form for those who prefer it 12: public static object Create<TInterface>(object target, TimeSpan threshold) 13: { 14: return Create(typeof(TInterface), target, threshold); 15: } 16:  17: // Form that uses type instead 18: public static object Create(Type interfaceType, object target, TimeSpan threshold) 19: { 20: return _generator.CreateInterfaceProxyWithTarget(interfaceType, target, 21: new TimedThreshold(threshold, level)); 22: } 23:  24: // The interceptor that is created to intercept the interface calls. 25: // Hidden as a private inner class so not exposing Castle libraries. 26: private class TimedThreshold : IInterceptor 27: { 28: // The threshold as a positive timespan that triggers a log message. 29: private readonly TimeSpan _threshold; 30:  31: // interceptor constructor 32: public TimedThreshold(TimeSpan threshold) 33: { 34: _threshold = threshold; 35: } 36:  37: // Intercept functor for each method invokation 38: public void Intercept(IInvocation invocation) 39: { 40: // time the method invocation 41: var timer = Stopwatch.StartNew(); 42:  43: // the Castle magic that tells the method to go ahead 44: invocation.Proceed(); 45:  46: timer.Stop(); 47:  48: // check if threshold is exceeded 49: if (timer.Elapsed > _threshold) 50: { 51: _log.WarnFormat("Long execution in {0} took {1} ms", 52: invocation.Method.Name, 53: timer.ElapsedMillseconds); 54: } 55: } 56: } 57: } Yes, it's a bit longer, but notice that: This class ONLY deals with logging long method calls, no DAO interface leftovers. This class can be used to time ANY class that has an interface or virtual methods. Personally, I like to wrap and hide the usage of DynamicProxy and IInterceptor so that anyone who uses this class doesn't need to know to add a Castle library reference.  As far as they are concerned, they're using my interceptor.  If I change to a new library if a better one comes along, they're insulated. Now, all we have to do to use this is to tell it to wrap our ProductDao and it does the rest: 1: // wraps a new ProductDao with a timing interceptor with a threshold of 5 seconds 2: IProductDao dao = TimeThresholdInterceptor.Create<IProductDao>(new ProductDao(), 5000); Automatic decoration of all methods!  You can even refine the proxy so that it only intercepts certain methods. This is ideal for so many things.  These are just some of the interceptors we've dreamed up and use: Log parameters and returns of methods to XML for auditing. Block invocations to methods and return default value (stubbing). Throw exception if certain methods are called (good for blocking access to deprecated methods). Log entrance and exit of a method and the duration. Log a message if a method takes more than a given time threshold to execute. Whether you use DynamicProxy or some other technology, I hope you see the benefits this adds.  Does it completely eliminate all need for the Decorator pattern?  No, there may still be cases where you want to decorate a particular class with functionality that doesn't apply to the world at large. But for all those cases where you are using Decorator to add functionality that's truly generic.  I strongly suggest you give this a try!

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• Visualize flowchart diagram with multiple end symbols

  - by platzhirsch

  I am looking for a standardize way to visualize the following hierarchical logic: The state of the thread is represented by the answers to the hierarchical set of question You can read this listing like a flowchart, you iterate over the questions decide, go one step deeper and so on. Therefore I thought the best way to visualize it, using a flowchart. The problem is, in this hierarchical set it is possible to end in more than one state and its totally valid. I have never seen a flowchart where you can enter more than one state. Is it still possible and I am missing the right symbol to present this logic or are flowchart not fitting anyway? What other graphical representation could I use, is there something fitting in UML? A non-deterministic state machine seems not to be intuitive enough, transfering it into a deterministic state machine would result in to many states, and so on.

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• Big Data – Buzz Words: What is Hadoop – Day 6 of 21

  - by Pinal Dave

  In yesterday’s blog post we learned what is NoSQL. In this article we will take a quick look at one of the four most important buzz words which goes around Big Data – Hadoop. What is Hadoop? Apache Hadoop is an open-source, free and Java based software framework offers a powerful distributed platform to store and manage Big Data. It is licensed under an Apache V2 license. It runs applications on large clusters of commodity hardware and it processes thousands of terabytes of data on thousands of the nodes. Hadoop is inspired from Google’s MapReduce and Google File System (GFS) papers. The major advantage of Hadoop framework is that it provides reliability and high availability. What are the core components of Hadoop? There are two major components of the Hadoop framework and both fo them does two of the important task for it. Hadoop MapReduce is the method to split a larger data problem into smaller chunk and distribute it to many different commodity servers. Each server have their own set of resources and they have processed them locally. Once the commodity server has processed the data they send it back collectively to main server. This is effectively a process where we process large data effectively and efficiently. (We will understand this in tomorrow’s blog post). Hadoop Distributed File System (HDFS) is a virtual file system. There is a big difference between any other file system and Hadoop. When we move a file on HDFS, it is automatically split into many small pieces. These small chunks of the file are replicated and stored on other servers (usually 3) for the fault tolerance or high availability. (We will understand this in the day after tomorrow’s blog post). Besides above two core components Hadoop project also contains following modules as well. Hadoop Common: Common utilities for the other Hadoop modules Hadoop Yarn: A framework for job scheduling and cluster resource management There are a few other projects (like Pig, Hive) related to above Hadoop as well which we will gradually explore in later blog posts. A Multi-node Hadoop Cluster Architecture Now let us quickly see the architecture of the a multi-node Hadoop cluster. A small Hadoop cluster includes a single master node and multiple worker or slave node. As discussed earlier, the entire cluster contains two layers. One of the layer of MapReduce Layer and another is of HDFC Layer. Each of these layer have its own relevant component. The master node consists of a JobTracker, TaskTracker, NameNode and DataNode. A slave or worker node consists of a DataNode and TaskTracker. It is also possible that slave node or worker node is only data or compute node. The matter of the fact that is the key feature of the Hadoop. In this introductory blog post we will stop here while describing the architecture of Hadoop. In a future blog post of this 31 day series we will explore various components of Hadoop Architecture in Detail. Why Use Hadoop? There are many advantages of using Hadoop. Let me quickly list them over here: Robust and Scalable – We can add new nodes as needed as well modify them. Affordable and Cost Effective – We do not need any special hardware for running Hadoop. We can just use commodity server. Adaptive and Flexible – Hadoop is built keeping in mind that it will handle structured and unstructured data. Highly Available and Fault Tolerant – When a node fails, the Hadoop framework automatically fails over to another node. Why Hadoop is named as Hadoop? In year 2005 Hadoop was created by Doug Cutting and Mike Cafarella while working at Yahoo. Doug Cutting named Hadoop after his son’s toy elephant. Tomorrow In tomorrow’s blog post we will discuss Buzz Word – MapReduce. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Big Data, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL

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• Documentation in Oracle Retail Merchandising System (RMS) and Oracle Retail Fiscal Management System (ORFM), Release 13.2.4

  - by Oracle Retail Documentation Team

  The Patch Release 13.2.4 of the Oracle Retail Merchandising System (RMS) and its module, Oracle Retail Fiscal Management (ORFM)  is now available from My Oracle Support. End User Documentation Enhancements The following summarize the highlights of changes made to the documentation in conjunction with the new Brazil-related functionality: Foundation chapter in the Oracle Retail Merchandising System (RMS)/Sales Audit (ReSA) Brazil Localization User GuideThis chapter was updated with a non-base Localization Flexible Attribution Solution (LFAS) section that addresses the addition of several new custom attributes to Items and Suppliers through non-base LFAS for Brazil; it also addresses the extension of the Retail Tax Integration Layer (RTIL) through the Oracle Retail Merchandising System (RMS), and Oracle Retail Fiscal Management System (ORFM).  ORFM User GuideThe Purchase Order chapter was updated to include schedule related updates for a Nota Fiscal. The Fiscal Documents chapter was updated to include information on creating a new NF and searching for details using Vendor Product Number. Oracle Retail Fiscal Management/RMS Brazil Localization Implementation GuideThe Implementation Checklist chapter was updated with a note on multi-currency functionality. The Batch Processes chapter was updated with information on the NF EDI batch. The following summarize the highlights of changes made to the documentation in conjunction with the new technical certifications (see the RMS 13.2.4 Release Notes for more information): Installation Guides for RMS and for ORFM/RMS BrazilThese installation guides were updated extensively to account for the multiple technical certification enhancements in 13.2.4. White Paper: How to Upgrade from WebLogic11g 10.3.3 to WebLogic11g 10.3.4  (Doc ID: 1432575.1)See the previous blog entry regarding this new White Paper. New Documents on My Oracle Support for Brazil Localization Overview and Interfaces Tax Vendor Integration (Doc ID: 1424048.1)Oracle chooses to integrate with a third party tax expert to delivery the Brazilian solution. Oracle has built the Retail Tax Integration layer (RTIL) as the key integration component to support the integration of Oracle suite of products with external tax vendors. This paper addresses the RTIL integration interfaces with TaxWeb, providing guidance on the typical integration interfaces and operations that must be supported by other tax solutions in the Brazilian market. Oracle Retail Fiscal Management/RMS Brazil Localization: Localization Flexible Attribute Solution (LFAS) (Doc ID: 1418509.1)The white paper covers the definition of custom attributes in Localization Flexible Attribute Solution (LFAS) and enables retailers to perform data conversion changes. Retailers can add several new custom attributes to Items and Suppliers through non-base LFAS for Brazil and extend Retail Tax Integration Layer (RTIL) through the Oracle Retail Merchandising System (RMS), and Oracle Retail Fiscal Management System (RFM). Documents Published in RMS and ORFM Release 13.2.4 Oracle Retail Merchandising System Release Notes Oracle Retail Merchandising System Installation Guide Oracle Retail Merchandising System User Guide and Online Help Oracle Retail Sales Audit (ReSA) User Guide and Online Help Oracle Retail Merchandising System Operations Guide Oracle Retail Merchandising System Data Model Oracle Retail Merchandising Batch Schedule Oracle Retail Merchandising Implementation Guide Oracle Retail POS Suite 13.4.1 / Merchandising Operations Management13.2.4 Implementation Guide Oracle Retail Fiscal Management Data Model Oracle Retail Fiscal Management/RMS Brazil Localization Installation Guide Oracle Retail Fiscal Management/RMS Brazil Localization Implementation Guide Oracle Retail Fiscal Management User Guide and Online Help

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• Newbie worried about CASE tool.

  - by Jason Evans

  Hi there. I'm looking for some guidance on CASE tools and whether my concerns are valid. Recently I was in a meeting between my employer and an external software company which have a CASE tool currently in beta. They demonstrated this tool to us, showing how you build a UML model in Enterprise Architect (or something like it) and then, through their tool, that UML model is transformed into a Visual Studio project, with C# files, stored procedures for SQL Server, code for the data layer, WCF stuff, logging code and allsorts. Now, admittedly, I don't see the point in this, as in I'm not convinced it will save that much time (plus it feels like overkill). The tool authors said that a trial of the tool at another company had saved a team there 5 weeks of development time (from 6 weeks down to about 1 week) using this tool. I find the accuracy of that estimate hard to believe. My main concern is whether using this tool is going slow down my productivity. For example - Say I have a UML model which I built a VS solution from. Now, I want to rename a class method to something else; will this mean having to update the UML model first and then rebuilding the code? Is this how case tools normally work? Something I will need to check with the authors is the structure of the generated VS solution. I like the Domain Driven Design way of project structure - Infrstructure, Services, Model, etc. I doubt very much this tool will do that. Also, I've been playing around with Entity Framework Code First and think it's a great way to build the data model. I have nice repositories, unit of work classes and other design patterns that work well with EF. I have data anootations and stuff like that working great. By not having EF (the CASE tool uses it's own data layer code) I'm concerned that this tool's data layer code might not be a nice to integrate in the UoW pattern, repositories, etc. This I will need to verify when I get a closer look at the generated code. What are other people's experiences with CASE tools? Am I being paranoid about nothing? Am I being unfair - are my negativities unfounded? EDIT: I like to use TDD/BDD for building my code, and using a CASE tool looks like it will make this difficult. Again, any feedback on this would be great. Cheers. Jas.

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• Wordpress Installation (on IIS and SQL Server)

  - by Davide Mauri

  To proceed with the installation of Wordpress on SQL Server and IIS, first of all, you need to do the following steps Create a database on SQL Server that will be used by Wordpress Create login that can access to the just created database and put the user into ddladmin, db_datareader, db_datawriter roles Download and unpack Wordpress 3.3.2 (latest version as of 27 May 2012) zip file into a directory of your choice Download the wp-db-abstraction 1.1.4 (latest version as of 27 May 2012) plugin from wordpress.org website Now that the basic action has been done, you can start to setup and configure your Wordpress installation. Unpack and follow the instructions in the README.TXT file to install the Database Abstraction Layer. Mainly you have to: Upload wp-db-abstraction.php and the wp-db-abstraction directory to wp-content/mu-plugins.  This should be parallel to your regular plugins directory.  If the mu-plugins directory does not exist, you must create it. Put the db.php file from inside the wp-db-abstraction.php directory to wp-content/db.php Now you can create an application pool in IIS like the following one Create a website, using the above Application Pool, that points to the folder where you unpacked Wordpress files. Be sure to give the “Write” permission to the IIS account, as pointed out in this (old, but still quite valid) installation manual: http://wordpress.visitmix.com/development/installing-wordpress-on-sql-server#iis Now you’re ready to go. Point your browser to the configured website and the Wordpress installation screen will be there for you. When you’re requested to enter information to connect to MySQL database, simply skip that page, leaving the default values. If you have installed the Database Abstraction Layer, another database installation screen will appear after the one used by MySQL, and here you can enter the configuration information needed to connect to SQL Server. After having finished the installation steps, you should be able to access and navigate your wordpress site.  A final touch, and it’s done: just add the needed rewrite rules http://wordpress.visitmix.com/development/installing-wordpress-on-sql-server#urlrewrite and that’s it! Well. Not really. Unfortunately the current (as of 27 May 2012) version of the Database Abstraction Layer (1.1.4) has some bugs. Luckily they can be quickly fixed: Backslash Fix http://wordpress.org/support/topic/plugin-wp-db-abstraction-fix-problems-with-backslash-usage Select Top 0 Fix Make the change to the file “.\wp-content\mu-plugins\wp-db-abstraction\translations\sqlsrv\translations.php” suggested by “debettap”   http://sourceforge.net/tracker/?func=detail&aid=3485384&group_id=315685&atid=1328061 And now you have a 100% working Wordpress installation on SQL Server! Since I also wanted to take advantage of SQL Server Full Text Search, I’ve created a very simple wordpress plugin to setup full-text search and to use it as website search engine: http://wpfts.codeplex.com/ Enjoy!

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• What is a best practice tier structure of a Java EE 6/7 application?

  - by James Drinkard

  I was attempting to find a best practice for modeling the tiers in a Java EE application yesterday and couldn't come up with anything current. In the past, say java 1.4, it was four tiers: Presentation Tier Web Tier Business Logic Tier DAL (Data Access Layer ) which I always considered a tier and not a layer. After working with Web Services and SOA I thought to add in a services tier, but that may fall under 3. the business logic tier. I did searches for quite a while and reading articles. It seems like Domain Driven Design is becoming more popular, but I couldn't find a diagram on it's tier structure. Anyone have ideas or diagrams on what the proper tier structure is for newer Java EE applications or is it really the same, but more items are ranked under the four I've mentioned?

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• Most efficient way to rebuild a tree structure from data

  - by Ahsan

  Have a question on recursively populating JsTree using the .NET wrapper available via NuGet. Any help would be greatly appreciated. the .NET class JsTree3Node has a property named Children which holds a list of JsTree3Nodes, and the pre-existing table which contains the node structure looks like this NodeId ParentNodeId Data AbsolutePath 1 NULL News /News 2 1 Financial /News/Financial 3 2 StockMarket /News/Financial/StockMarket I have a EF data context from the the database, so my code currently looks like this. var parentNode = new JsTree3Node(Guid.NewGuid().ToString()); foreach(var nodeItem in context.Nodes) { parentNode.Children.Add(nodeItem.Data); // What is the most efficient logic to do this recursively? } as the inline comment says in the above code, what would be the most efficient way to load the JStree data on to the parentNode object. I can change the existing node table to suite the logic so feel free to suggest any changes to improve performance.

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• Given the presentation model pattern, is the view, presentation model, or model responsible for adding child views to an existing view at runtime?

  - by Ryan Taylor

  I am building a Flex 4 based application using the presentation model design pattern. This application will have several different components to it as shown in the image below. The MainView and DashboardView will always be visible and they each have corresponding presentation models and models as necessary. These views are easily created by declaring their MXML in the application root. <s:HGroup width="100%" height="100%"> <MainView width="75% height="100%"/> <DashboardView width="25%" height="100%"/> </s:HGroup> There will also be many WidgetViewN views that can be added to the DashboardView by the user at runtime through a simple drop down list. This will need to be accomplished via ActionScript. The drop down list should always show what WidgetViewN has already been added to the DashboardView. Therefore some state about which WidgetViewN's have been created needs to be stored. Since the list of available WidgetViewN and which ones are added to the DashboardView also need to be accessible from other components in the system I think this needs to be stored in a Model object. My understanding of the presentation model design pattern is that the view is very lean. It contains as close to zero logic as is practical. The view communicates/binds to the presentation model which contains all the necessary view logic. The presentation model is effectively an abstract representation of the view which supports low coupling and eases testability. The presentation model may have one or more models injected in in order to display the necessary information. The models themselves contain no view logic whatsoever. So I have a several questions around this design. Who should be responsible for creating the WidgetViewN components and adding these to the DashboardView? Is this the responsibility of the DashboardView, DashboardPresentationModel, DashboardModel or something else entirely? It seems like the DashboardPresentationModel would be responsible for creating/adding/removing any child views from it's display but how do you do this without passing in the DashboardView to the DashboardPresentationModel? The list of available and visible WidgetViewN components needs to be accessible to a few other components as well. Is it okay for a reference to a WidgetViewN to be stored/referenced in a model? Are there any good examples of the presentation model pattern online in Flex that also include creating child views at runtime?

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• How to document/verify consistent layering?

  - by Morten

  I have recently moved to the dark side: I am now a CUSTOMER of software development -- mainly websites. With this new role comes new concerns. As a programmer i know how solid an application becomes when it is properly layered, and I want to use this knowledge in my new job. I don't want business logic in my presentation layer, and certainly not presentation stuff in my data layer. Thus, I want to be able to demand from my supllier that they document the level of layering, and how neat and consistent the layering is. The big question is: How is the level of layering documented to me as a customer, and is that a reasonable demmand for me to have, so I don't have to look in the code (I'm not supposed to do that anymore)?

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• What to do if I am working on a language that I don't like

  - by Sayem Ahmed

  Hi there, I really don't know if this is the right place to ask this question, but if it isn't, then I guess someone will notify. Anyway, I am working in a software development farm which is currently using PowerBuilder to develop a mid-size ERP solution. The work environment and company management are so great that it may be the best in the whole Bangladesh. Only problem is the technology that are currently being used, which is this PowerBuilder. Now I am a guy who tends to prefer modern development technologies, like DI containers, ORM, TDD, JQuery etc. PowerBuilder is a great tool too, but I couldn' like the application techniques used to build PB applications. These techniques are so inheritance-dependent that many a times these create a great deal of sufferings. I remember two days ago I had to change some processing logic in a core user object and as a result I had to test and re-test all the forms that the application have(apparently, there are almost 20 forms there, each of them with 3-4 kinds of functionalities). Also, learning PB is tough, because online material on this thing is very, very low. I can't afford to read all the documentation that PB provide because I have hard deadlines on the work that I have to do. Another thing with PB is that applications tend to rely on business logic that are implemented on databases which causes debugging to be a nightmare. As a result, I don't feel motivated enough to work in this IDE/System/Framework (or whatever) anymore. My productivity has greatly decreased, and I am not delivering quality code. I think I have the following options available to me - Remain in the current job, keep delivering worse code and let my productivity decrease day by day, taking salaries and bonuses but not delivering quality codes/doing my job the way I should, Search for a new job. At this point number 2 seems a good option, but there are also some issues. As I mentioned before, our management may be the best in the country. Our company owner is himself a software developer with 24 years of experience in software development. He is currently our Team Leader and System Analyst. He is by far the greatest manager and boss I have ever seen. He understands developer's mentality very well(as he IS himself a developer). He is also a great, kind and generous guy. Our company is only a start-up company with 10 developers. Among them, only 3-4 people knows about the business logic behind the ERP, and I am one of them. If I switch my current job, it may hamper the development of this product which I really don't want. I couldn't decide what to do in this situation, so I turned to the community for advice.

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