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• www-data can upload a file but cant move it after the upload action

  - by user70058

  I am currently running Apache and PHP on Ubuntu. I have a page where a user is supposed to upload a profile image. The action on the backend is supposed to work like this: Upload file to user directory -- WORKS! Refer to the uploaded file and create a thumbnail in directory thumbs -- DOES NOT WORK www-data has write access to directory thumbs. My guess is that www-data for some reason does not have proper access to the file that was uploaded. UPLOADED FILE PERMISSIONS -rw-r--r-- 1 www-data www-data 47057 Feb 8 23:24 0181c6e0973eb19cb0d98521a6fe1d9e71cd6daa.jpg THUMBS DIRECTORY PERMISSIONS drwxr-sr-x 2 www-data www-data 4096 Feb 8 23:23 thumbs Im at lost here. I'm new to Ubuntu as well. Any help would be greatly appreciated!

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• Syncing Data with a Server using Silverlight and HTTP Polling Duplex

  - by dwahlin

  Many applications have the need to stay in-sync with data provided by a service. Although web applications typically rely on standard polling techniques to check if data has changed, Silverlight provides several interesting options for keeping an application in-sync that rely on server “push” technologies. A few years back I wrote several blog posts covering different “push” technologies available in Silverlight that rely on sockets or HTTP Polling Duplex. We recently had a project that looked like it could benefit from pushing data from a server to one or more clients so I thought I’d revisit the subject and provide some updates to the original code posted. If you’ve worked with AJAX before in Web applications then you know that until browsers fully support web sockets or other duplex (bi-directional communication) technologies that it’s difficult to keep applications in-sync with a server without relying on polling. The problem with polling is that you have to check for changes on the server on a timed-basis which can often be wasteful and take up unnecessary resources. With server “push” technologies, data can be pushed from the server to the client as it changes. Once the data is received, the client can update the user interface as appropriate. Using “push” technologies allows the client to listen for changes from the data but stay 100% focused on client activities as opposed to worrying about polling and asking the server if anything has changed. Silverlight provides several options for pushing data from a server to a client including sockets, TCP bindings and HTTP Polling Duplex.  Each has its own strengths and weaknesses as far as performance and setup work with HTTP Polling Duplex arguably being the easiest to setup and get going.  In this article I’ll demonstrate how HTTP Polling Duplex can be used in Silverlight 4 applications to push data and show how you can create a WCF server that provides an HTTP Polling Duplex binding that a Silverlight client can consume.   What is HTTP Polling Duplex? Technologies that allow data to be pushed from a server to a client rely on duplex functionality. Duplex (or bi-directional) communication allows data to be passed in both directions.  A client can call a service and the server can call the client. HTTP Polling Duplex (as its name implies) allows a server to communicate with a client without forcing the client to constantly poll the server. It has the benefit of being able to run on port 80 making setup a breeze compared to the other options which require specific ports to be used and cross-domain policy files to be exposed on port 943 (as with sockets and TCP bindings). Having said that, if you’re looking for the best speed possible then sockets and TCP bindings are the way to go. But, they’re not the only game in town when it comes to duplex communication. The first time I heard about HTTP Polling Duplex (initially available in Silverlight 2) I wasn’t exactly sure how it was any better than standard polling used in AJAX applications. I read the Silverlight SDK, looked at various resources and generally found the following definition unhelpful as far as understanding the actual benefits that HTTP Polling Duplex provided: "The Silverlight client periodically polls the service on the network layer, and checks for any new messages that the service wants to send on the callback channel. The service queues all messages sent on the client callback channel and delivers them to the client when the client polls the service." Although the previous definition explained the overall process, it sounded as if standard polling was used. Fortunately, Microsoft’s Scott Guthrie provided me with a more clear definition several years back that explains the benefits provided by HTTP Polling Duplex quite well (used with his permission): "The [HTTP Polling Duplex] duplex support does use polling in the background to implement notifications – although the way it does it is different than manual polling. It initiates a network request, and then the request is effectively “put to sleep” waiting for the server to respond (it doesn’t come back immediately). The server then keeps the connection open but not active until it has something to send back (or the connection times out after 90 seconds – at which point the duplex client will connect again and wait). This way you are avoiding hitting the server repeatedly – but still get an immediate response when there is data to send." After hearing Scott’s definition the light bulb went on and it all made sense. A client makes a request to a server to check for changes, but instead of the request returning immediately, it parks itself on the server and waits for data. It’s kind of like waiting to pick up a pizza at the store. Instead of calling the store over and over to check the status, you sit in the store and wait until the pizza (the request data) is ready. Once it’s ready you take it back home (to the client). This technique provides a lot of efficiency gains over standard polling techniques even though it does use some polling of its own as a request is initially made from a client to a server. So how do you implement HTTP Polling Duplex in your Silverlight applications? Let’s take a look at the process by starting with the server. Creating an HTTP Polling Duplex WCF Service Creating a WCF service that exposes an HTTP Polling Duplex binding is straightforward as far as coding goes. Add some one way operations into an interface, create a client callback interface and you’re ready to go. The most challenging part comes into play when configuring the service to properly support the necessary binding and that’s more of a cut and paste operation once you know the configuration code to use. To create an HTTP Polling Duplex service you’ll need to expose server-side and client-side interfaces and reference the System.ServiceModel.PollingDuplex assembly (located at C:\Program Files (x86)\Microsoft SDKs\Silverlight\v4.0\Libraries\Server on my machine) in the server project. For the demo application I upgraded a basketball simulation service to support the latest polling duplex assemblies. The service simulates a simple basketball game using a Game class and pushes information about the game such as score, fouls, shots and more to the client as the game changes over time. Before jumping too far into the game push service, it’s important to discuss two interfaces used by the service to communicate in a bi-directional manner. The first is called IGameStreamService and defines the methods/operations that the client can call on the server (see Listing 1). The second is IGameStreamClient which defines the callback methods that a server can use to communicate with a client (see Listing 2).   [ServiceContract(Namespace = "Silverlight", CallbackContract = typeof(IGameStreamClient))] public interface IGameStreamService { [OperationContract(IsOneWay = true)] void GetTeamData(); } Listing 1. The IGameStreamService interface defines server operations that can be called on the server.   [ServiceContract] public interface IGameStreamClient { [OperationContract(IsOneWay = true)] void ReceiveTeamData(List<Team> teamData); [OperationContract(IsOneWay = true, AsyncPattern=true)] IAsyncResult BeginReceiveGameData(GameData gameData, AsyncCallback callback, object state); void EndReceiveGameData(IAsyncResult result); } Listing 2. The IGameStreamClient interfaces defines client operations that a server can call.   The IGameStreamService interface is decorated with the standard ServiceContract attribute but also contains a value for the CallbackContract property.  This property is used to define the interface that the client will expose (IGameStreamClient in this example) and use to receive data pushed from the service. Notice that each OperationContract attribute in both interfaces sets the IsOneWay property to true. This means that the operation can be called and passed data as appropriate, however, no data will be passed back. Instead, data will be pushed back to the client as it’s available.  Looking through the IGameStreamService interface you can see that the client can request team data whereas the IGameStreamClient interface allows team and game data to be received by the client. One interesting point about the IGameStreamClient interface is the inclusion of the AsyncPattern property on the BeginReceiveGameData operation. I initially created this operation as a standard one way operation and it worked most of the time. However, as I disconnected clients and reconnected new ones game data wasn’t being passed properly. After researching the problem more I realized that because the service could take up to 7 seconds to return game data, things were getting hung up. By setting the AsyncPattern property to true on the BeginReceivedGameData operation and providing a corresponding EndReceiveGameData operation I was able to get around this problem and get everything running properly. I’ll provide more details on the implementation of these two methods later in this post. Once the interfaces were created I moved on to the game service class. The first order of business was to create a class that implemented the IGameStreamService interface. Since the service can be used by multiple clients wanting game data I added the ServiceBehavior attribute to the class definition so that I could set its InstanceContextMode to InstanceContextMode.Single (in effect creating a Singleton service object). Listing 3 shows the game service class as well as its fields and constructor.   [ServiceBehavior(ConcurrencyMode = ConcurrencyMode.Multiple, InstanceContextMode = InstanceContextMode.Single)] public class GameStreamService : IGameStreamService { object _Key = new object(); Game _Game = null; Timer _Timer = null; Random _Random = null; Dictionary<string, IGameStreamClient> _ClientCallbacks = new Dictionary<string, IGameStreamClient>(); static AsyncCallback _ReceiveGameDataCompleted = new AsyncCallback(ReceiveGameDataCompleted); public GameStreamService() { _Game = new Game(); _Timer = new Timer { Enabled = false, Interval = 2000, AutoReset = true }; _Timer.Elapsed += new ElapsedEventHandler(_Timer_Elapsed); _Timer.Start(); _Random = new Random(); }} Listing 3. The GameStreamService implements the IGameStreamService interface which defines a callback contract that allows the service class to push data back to the client. By implementing the IGameStreamService interface, GameStreamService must supply a GetTeamData() method which is responsible for supplying information about the teams that are playing as well as individual players.  GetTeamData() also acts as a client subscription method that tracks clients wanting to receive game data.  Listing 4 shows the GetTeamData() method. public void GetTeamData() { //Get client callback channel var context = OperationContext.Current; var sessionID = context.SessionId; var currClient = context.GetCallbackChannel<IGameStreamClient>(); context.Channel.Faulted += Disconnect; context.Channel.Closed += Disconnect; IGameStreamClient client; if (!_ClientCallbacks.TryGetValue(sessionID, out client)) { lock (_Key) { _ClientCallbacks[sessionID] = currClient; } } currClient.ReceiveTeamData(_Game.GetTeamData()); //Start timer which when fired sends updated score information to client if (!_Timer.Enabled) { _Timer.Enabled = true; } } Listing 4. The GetTeamData() method subscribes a given client to the game service and returns. The key the line of code in the GetTeamData() method is the call to GetCallbackChannel<IGameStreamClient>().  This method is responsible for accessing the calling client’s callback channel. The callback channel is defined by the IGameStreamClient interface shown earlier in Listing 2 and used by the server to communicate with the client. Before passing team data back to the client, GetTeamData() grabs the client’s session ID and checks if it already exists in the _ClientCallbacks dictionary object used to track clients wanting callbacks from the server. If the client doesn’t exist it adds it into the collection. It then pushes team data from the Game class back to the client by calling ReceiveTeamData().  Since the service simulates a basketball game, a timer is then started if it’s not already enabled which is then used to randomly send data to the client. When the timer fires, game data is pushed down to the client. Listing 5 shows the _Timer_Elapsed() method that is called when the timer fires as well as the SendGameData() method used to send data to the client. void _Timer_Elapsed(object sender, ElapsedEventArgs e) { int interval = _Random.Next(3000, 7000); lock (_Key) { _Timer.Interval = interval; _Timer.Enabled = false; } SendGameData(_Game.GetGameData()); } private void SendGameData(GameData gameData) { var cbs = _ClientCallbacks.Where(cb => ((IContextChannel)cb.Value).State == CommunicationState.Opened); for (int i = 0; i < cbs.Count(); i++) { var cb = cbs.ElementAt(i).Value; try { cb.BeginReceiveGameData(gameData, _ReceiveGameDataCompleted, cb); } catch (TimeoutException texp) { //Log timeout error } catch (CommunicationException cexp) { //Log communication error } } lock (_Key) _Timer.Enabled = true; } private static void ReceiveGameDataCompleted(IAsyncResult result) { try { ((IGameStreamClient)(result.AsyncState)).EndReceiveGameData(result); } catch (CommunicationException) { // empty } catch (TimeoutException) { // empty } } LIsting 5. _Timer_Elapsed is used to simulate time in a basketball game. When _Timer_Elapsed() fires the SendGameData() method is called which iterates through the clients wanting to be notified of changes. As each client is identified, their respective BeginReceiveGameData() method is called which ultimately pushes game data down to the client. Recall that this method was defined in the client callback interface named IGameStreamClient shown earlier in Listing 2. Notice that BeginReceiveGameData() accepts _ReceiveGameDataCompleted as its second parameter (an AsyncCallback delegate defined in the service class) and passes the client callback as the third parameter. The initial version of the sample application had a standard ReceiveGameData() method in the client callback interface. However, sometimes the client callbacks would work properly and sometimes they wouldn’t which was a little baffling at first glance. After some investigation I realized that I needed to implement an asynchronous pattern for client callbacks to work properly since 3 – 7 second delays are occurring as a result of the timer. Once I added the BeginReceiveGameData() and ReceiveGameDataCompleted() methods everything worked properly since each call was handled in an asynchronous manner. The final task that had to be completed to get the server working properly with HTTP Polling Duplex was adding configuration code into web.config. In the interest of brevity I won’t post all of the code here since the sample application includes everything you need. However, Listing 6 shows the key configuration code to handle creating a custom binding named pollingDuplexBinding and associate it with the service’s endpoint.   <bindings> <customBinding> <binding name="pollingDuplexBinding"> <binaryMessageEncoding /> <pollingDuplex maxPendingSessions="2147483647" maxPendingMessagesPerSession="2147483647" inactivityTimeout="02:00:00" serverPollTimeout="00:05:00"/> <httpTransport /> </binding> </customBinding> </bindings> <services> <service name="GameService.GameStreamService" behaviorConfiguration="GameStreamServiceBehavior"> <endpoint address="" binding="customBinding" bindingConfiguration="pollingDuplexBinding" contract="GameService.IGameStreamService"/> <endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange" /> </service> </services>   Listing 6. Configuring an HTTP Polling Duplex binding in web.config and associating an endpoint with it. Calling the Service and Receiving “Pushed” Data Calling the service and handling data that is pushed from the server is a simple and straightforward process in Silverlight. Since the service is configured with a MEX endpoint and exposes a WSDL file, you can right-click on the Silverlight project and select the standard Add Service Reference item. After the web service proxy is created you may notice that the ServiceReferences.ClientConfig file only contains an empty configuration element instead of the normal configuration elements created when creating a standard WCF proxy. You can certainly update the file if you want to read from it at runtime but for the sample application I fed the service URI directly to the service proxy as shown next: var address = new EndpointAddress("http://localhost.:5661/GameStreamService.svc"); var binding = new PollingDuplexHttpBinding(); _Proxy = new GameStreamServiceClient(binding, address); _Proxy.ReceiveTeamDataReceived += _Proxy_ReceiveTeamDataReceived; _Proxy.ReceiveGameDataReceived += _Proxy_ReceiveGameDataReceived; _Proxy.GetTeamDataAsync(); This code creates the proxy and passes the endpoint address and binding to use to its constructor. It then wires the different receive events to callback methods and calls GetTeamDataAsync().  Calling GetTeamDataAsync() causes the server to store the client in the server-side dictionary collection mentioned earlier so that it can receive data that is pushed.  As the server-side timer fires and game data is pushed to the client, the user interface is updated as shown in Listing 7. Listing 8 shows the _Proxy_ReceiveGameDataReceived() method responsible for handling the data and calling UpdateGameData() to process it.   Listing 7. The Silverlight interface. Game data is pushed from the server to the client using HTTP Polling Duplex. void _Proxy_ReceiveGameDataReceived(object sender, ReceiveGameDataReceivedEventArgs e) { UpdateGameData(e.gameData); } private void UpdateGameData(GameData gameData) { //Update Score this.tbTeam1Score.Text = gameData.Team1Score.ToString(); this.tbTeam2Score.Text = gameData.Team2Score.ToString(); //Update ball visibility if (gameData.Action != ActionsEnum.Foul) { if (tbTeam1.Text == gameData.TeamOnOffense) { AnimateBall(this.BB1, this.BB2); } else //Team 2 { AnimateBall(this.BB2, this.BB1); } } if (this.lbActions.Items.Count > 9) this.lbActions.Items.Clear(); this.lbActions.Items.Add(gameData.LastAction); if (this.lbActions.Visibility == Visibility.Collapsed) this.lbActions.Visibility = Visibility.Visible; } private void AnimateBall(Image onBall, Image offBall) { this.FadeIn.Stop(); Storyboard.SetTarget(this.FadeInAnimation, onBall); Storyboard.SetTarget(this.FadeOutAnimation, offBall); this.FadeIn.Begin(); } Listing 8. As the server pushes game data, the client’s _Proxy_ReceiveGameDataReceived() method is called to process the data. In a real-life application I’d go with a ViewModel class to handle retrieving team data, setup data bindings and handle data that is pushed from the server. However, for the sample application I wanted to focus on HTTP Polling Duplex and keep things as simple as possible.   Summary Silverlight supports three options when duplex communication is required in an application including TCP bindins, sockets and HTTP Polling Duplex. In this post you’ve seen how HTTP Polling Duplex interfaces can be created and implemented on the server as well as how they can be consumed by a Silverlight client. HTTP Polling Duplex provides a nice way to “push” data from a server while still allowing the data to flow over port 80 or another port of your choice.   Sample Application Download

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• Oracle Enterprise Data Quality Adds Global Address Verification Capabilities for Greater Accuracy and Broader Location Coverage

  - by Mala Narasimharajan

  Data quality – has many flavors to it.  Product, Customer – you name the data domain and there’s data quality associated with it.  Address verification and data quality are a little different.  in that there is a tremendous amount of variation as well as nuance attached to it.  Specifically, what makes address verification challenging is that more often than not, addresses are incomplete, riddled with misspellings, incorrect postal codes are assigned to locations or non-address items are present.  Almost all data has locations, and accurate locations power a wealth of business processes: Customer Relationship Management, data quality, delivery of materials, goods or services, fraud detection, insurance risk assessment, data analytics, store and territory planning, and much more. Oracle Address Verification Server provides location-based services as well as deeper parsing and analysis capabilities for Oracle Enterprise Data Quality.  Specifically, Pre-integrated with the EDQ platform, Oracle Address Verification Server provides robust parsing, validation, as well as specialized location information for over 240 countries – all populated countries on Earth.  Oracle Enterprise Data Quality (EDQ) is a data quality platform, dedicated to address the distinct challenges of customer and product data quality, and performs advanced data profiling to identify and measure poor quality data and identify rule requirements, as well as semantic and pattern-based recognition to accurately parse and standardize data that is poorly structured.   EDQ is integrated with Oracle Master Data Management, including Oracle Customer Hub and Oracle Product Hub, as well as Oracle Data Integrator Enterprise Edition and Oracle CRM.  Address Verification Server provides key address verification services for Oracle CRM and Oracle Customer Hub.  In addition, Address Verification Server provides greater accuracy when handling address data due to its expanded sources and extensible knowledge repository, solid parsing across locales and countries as well as  adept handling of extraneous data in address fields.  For more information on Oracle Address Verification Server visit:  http://bit.ly/GMUE4H and http://bit.ly/GWf7U6

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• Ubuntu boots in read-only filesystem after upgrade!

  - by akatzbreaker

  I got a serious problem here: I recently upgraded to the Latest Version of Ubuntu. Now, I boot to my Ubuntu Partition, and I get a Low-Graphics error! I boot to a Recovery-Mode to see what the Problem is. Then, I try to Fix any Damaged Packages, to run fsck but nothing solved the Problem. Then, from the Recovery Menu, I open a Root Shell. I try to create a File and I understand that the Filesystem is Read-Only. Then, I run: mount -o remount,rw / and it Worked for that Terminal Session! When I go back to recovery, I select to resume Boot Normally but I get the Same Error! a I also tried to Boot to my Root Shell again, remount as Read-Write and Start Gnome from there. It Worked! (But the user is ROOT, and is quite Dangerous!) However, I can't do all this proccess at every boot! Any Solution? (Note that when I try to create a new File in my Ubuntu Partition from another OS, I don't get any Errors!)

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• External hard drive failing, is backup recovery possible?

  - by backitup

  I have a Seagate Freeagent external hard drive. While I was backing it up on Windows XP my pc crashed and I received the horrifying "Delayed Write Error" when I rebooted citing "$MFT" and a few other files. I tried to unmount it, but to no avail. Now my pc just crashes when I try to access it via Windows. In Ubuntu I am able to view it through disk utility. SMART status is "DISK FAILURE IMMINENT". Fdisk doesn't work, and the SMART tests fail on "Reallocated Sector Count". Is there any way for me to rescue any of my data. I can still access the drive but as soon as I do that it crashes.

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• Making Spring Data JPA work with DataNucleus (GAE) (Spring Boot)

  - by xybrek

  There are several hints that Spring Data works with Google App Engine like: http://tommysiu.blogspot.com/2014/01/spring-data-on-gae-part-1.html http://blog.eisele.net/2009/07/spring-300m3-on-google-appengine-with.html Much of the examples are not "Spring Boot" so I've been trying to retrofit things with it. However, I've been stuck with this error for days and days: [INFO] Caused by: java.lang.NullPointerException [INFO] at org.datanucleus.api.jpa.metamodel.SingularAttributeImpl.isVersion(SingularAttributeImpl.java:79) [INFO] at org.springframework.data.jpa.repository.support.JpaMetamodelEntityInformation.findVersionAttribute(JpaMetamodelEntityInformation.java:102) [INFO] at org.springframework.data.jpa.repository.support.JpaMetamodelEntityInformation.<init>(JpaMetamodelEntityInformation.java:79) [INFO] at org.springframework.data.jpa.repository.support.JpaEntityInformationSupport.getMetadata(JpaEntityInformationSupport.java:65) [INFO] at org.springframework.data.jpa.repository.support.JpaRepositoryFactory.getEntityInformation(JpaRepositoryFactory.java:149) [INFO] at org.springframework.data.jpa.repository.support.JpaRepositoryFactory.getTargetRepository(JpaRepositoryFactory.java:88) [INFO] at org.springframework.data.jpa.repository.support.JpaRepositoryFactory.getTargetRepository(JpaRepositoryFactory.java:68) [INFO] at org.springframework.data.repository.core.support.RepositoryFactorySupport.getRepository(RepositoryFactorySupport.java:158) [INFO] at org.springframework.data.repository.core.support.RepositoryFactoryBeanSupport.initAndReturn(RepositoryFactoryBeanSupport.java:224) [INFO] at org.springframework.data.repository.core.support.RepositoryFactoryBeanSupport.afterPropertiesSet(RepositoryFactoryBeanSupport.java:210) [INFO] at org.springframework.data.jpa.repository.support.JpaRepositoryFactoryBean.afterPropertiesSet(JpaRepositoryFactoryBean.java:92) [INFO] at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory$6.run(AbstractAutowireCapableBeanFactory.java:1602) [INFO] at java.security.AccessController.doPrivileged(Native Method) [INFO] at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1599) [INFO] at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1549) [INFO] ... 40 more Where, I'm trying to use Spring Data JPA with DataNucleus/AppEngine: @Configuration @ComponentScan @EnableJpaRepositories @EnableTransactionManagement class JpaApplicationConfig { private static final Logger logger = Logger .getLogger(JpaApplicationConfig.class.getName()); @Bean public EntityManagerFactory entityManagerFactory() { logger.info("Loading Entity Manager..."); return Persistence .createEntityManagerFactory("transactions-optional"); } @Bean public PlatformTransactionManager transactionManager() { logger.info("Loading Transaction Manager..."); final JpaTransactionManager txManager = new JpaTransactionManager(); txManager.setEntityManagerFactory(entityManagerFactory()); return txManager; } } I've tested Persistence.createEntityManagerFactory("transactions-optional"); to see if the app can persist using this EMF, well, it does, so I am sure that this EMF works fine. The problem is the "wiring" up with the Spring Data JPA, can anybody help?

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• Parse and read data frame in C?

  - by user253656

  I am writing a program that reads the data from the serial port on Linux. The data are sent by another device with the following frame format: |start | Command | Data | CRC | End | |0x02 | 0x41 | (0-127 octets) | | 0x03| ---------------------------------------------------- The Data field contains 127 octets as shown and octet 1,2 contains one type of data; octet 3,4 contains another data. I need to get these data I know how to write and read data to and from a serial port in Linux, but it is just to write and read a simple string (like "ABD") My issue is that I do not know how to parse the data frame formatted as above so that I can: get the data in octet 1,2 in the Data field get the data in octet 3,4 in the Data field get the value in CRC field to check the consistency of the data Here the sample snip code that read and write a simple string from and to a serial port in Linux: int writeport(int fd, char *chars) { int len = strlen(chars); chars[len] = 0x0d; // stick a <CR> after the command chars[len+1] = 0x00; // terminate the string properly int n = write(fd, chars, strlen(chars)); if (n < 0) { fputs("write failed!\n", stderr); return 0; } return 1; } int readport(int fd, char *result) { int iIn = read(fd, result, 254); result[iIn-1] = 0x00; if (iIn < 0) { if (errno == EAGAIN) { printf("SERIAL EAGAIN ERROR\n"); return 0; } else { printf("SERIAL read error %d %s\n", errno, strerror(errno)); return 0; } } return 1; } Does anyone please have some ideas? Thanks all.

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• Oracle Coherence, Split-Brain and Recovery Protocols In Detail

  - by Ricardo Ferreira

  This article provides a high level conceptual overview of Split-Brain scenarios in distributed systems. It will focus on a specific example of cluster communication failure and recovery in Oracle Coherence. This includes a discussion on the witness protocol (used to remove failed cluster members) and the panic protocol (used to resolve Split-Brain scenarios). Note that the removal of cluster members does not necessarily indicate a Split-Brain condition. Oracle Coherence does not (and cannot) detect a Split-Brain as it occurs, the condition is only detected when cluster members that previously lost contact with each other regain contact. Cluster Topology and Configuration In order to create an good didactic for the article, let's assume a cluster topology and configuration. In this example we have a six member cluster, consisting of one JVM on each physical machine. The member IDs are as follows: Member ID  IP Address  1  10.149.155.76  2  10.149.155.77  3  10.149.155.236  4  10.149.155.75  5  10.149.155.79  6  10.149.155.78 Members 1, 2, and 3 are connected to a switch, and members 4, 5, and 6 are connected to a second switch. There is a link between the two switches, which provides network connectivity between all of the machines. Member 1 is the first member to join this cluster, thus making it the senior member. Member 6 is the last member to join this cluster. Here is a log snippet from Member 6 showing the complete member set: 2010-02-26 15:27:57.390/3.062 Oracle Coherence GE 3.5.3/465p2 <Info> (thread=main, member=6): Started DefaultCacheServer... SafeCluster: Name=cluster:0xDDEB Group{Address=224.3.5.3, Port=35465, TTL=4} MasterMemberSet ( ThisMember=Member(Id=6, Timestamp=2010-02-26 15:27:58.635, Address=10.149.155.78:8088, MachineId=1102, Location=process:228, Role=CoherenceServer) OldestMember=Member(Id=1, Timestamp=2010-02-26 15:27:06.931, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer) ActualMemberSet=MemberSet(Size=6, BitSetCount=2 Member(Id=1, Timestamp=2010-02-26 15:27:06.931, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer) Member(Id=2, Timestamp=2010-02-26 15:27:17.847, Address=10.149.155.77:8088, MachineId=1101, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:296, Role=CoherenceServer) Member(Id=3, Timestamp=2010-02-26 15:27:24.892, Address=10.149.155.236:8088, MachineId=1260, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:32459, Role=CoherenceServer) Member(Id=4, Timestamp=2010-02-26 15:27:39.574, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer) Member(Id=5, Timestamp=2010-02-26 15:27:49.095, Address=10.149.155.79:8088, MachineId=1103, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:3229, Role=CoherenceServer) Member(Id=6, Timestamp=2010-02-26 15:27:58.635, Address=10.149.155.78:8088, MachineId=1102, Location=process:228, Role=CoherenceServer) ) RecycleMillis=120000 RecycleSet=MemberSet(Size=0, BitSetCount=0 ) ) At approximately 15:30, the connection between the two switches is severed: Thirty seconds later (the default packet timeout in development mode) the logs indicate communication failures across the cluster. In this example, the communication failure was caused by a network failure. In a production setting, this type of communication failure can have many root causes, including (but not limited to) network failures, excessive GC, high CPU utilization, swapping/virtual memory, and exceeding maximum network bandwidth. In addition, this type of failure is not necessarily indicative of a split brain. Any communication failure will be logged in this fashion. Member 2 logs a communication failure with Member 5: 2010-02-26 15:30:32.638/196.928 Oracle Coherence GE 3.5.3/465p2 <Warning> (thread=PacketPublisher, member=2): Timeout while delivering a packet; requesting the departure confirmation for Member(Id=5, Timestamp=2010-02-26 15:27:49.095, Address=10.149.155.79:8088, MachineId=1103, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:3229, Role=CoherenceServer) by MemberSet(Size=2, BitSetCount=2 Member(Id=1, Timestamp=2010-02-26 15:27:06.931, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer) Member(Id=4, Timestamp=2010-02-26 15:27:39.574, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer) ) The Coherence clustering protocol (TCMP) is a reliable transport mechanism built on UDP. In order for the protocol to be reliable, it requires an acknowledgement (ACK) for each packet delivered. If a packet fails to be acknowledged within the configured timeout period, the Coherence cluster member will log a packet timeout (as seen in the log message above). When this occurs, the cluster member will consult with other members to determine who is at fault for the communication failure. If the witness members agree that the suspect member is at fault, the suspect is removed from the cluster. If the witnesses unanimously disagree, the accuser is removed. This process is known as the witness protocol. Since Member 2 cannot communicate with Member 5, it selects two witnesses (Members 1 and 4) to determine if the communication issue is with Member 5 or with itself (Member 2). However, Member 4 is on the switch that is no longer accessible by Members 1, 2 and 3; thus a packet timeout for member 4 is recorded as well: 2010-02-26 15:30:35.648/199.938 Oracle Coherence GE 3.5.3/465p2 <Warning> (thread=PacketPublisher, member=2): Timeout while delivering a packet; requesting the departure confirmation for Member(Id=4, Timestamp=2010-02-26 15:27:39.574, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer) by MemberSet(Size=2, BitSetCount=2 Member(Id=1, Timestamp=2010-02-26 15:27:06.931, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer) Member(Id=6, Timestamp=2010-02-26 15:27:58.635, Address=10.149.155.78:8088, MachineId=1102, Location=process:228, Role=CoherenceServer) ) Member 1 has the ability to confirm the departure of member 4, however Member 6 cannot as it is also inaccessible. At the same time, Member 3 sends a request to remove Member 6, which is followed by a report from Member 3 indicating that Member 6 has departed the cluster: 2010-02-26 15:30:35.706/199.996 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Cluster, member=2): MemberLeft request for Member 6 received from Member(Id=3, Timestamp=2010-02-26 15:27:24.892, Address=10.149.155.236:8088, MachineId=1260, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:32459, Role=CoherenceServer) 2010-02-26 15:30:35.709/199.999 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Cluster, member=2): MemberLeft notification for Member 6 received from Member(Id=3, Timestamp=2010-02-26 15:27:24.892, Address=10.149.155.236:8088, MachineId=1260, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:32459, Role=CoherenceServer) The log for Member 3 determines how Member 6 departed the cluster: 2010-02-26 15:30:35.161/191.694 Oracle Coherence GE 3.5.3/465p2 <Warning> (thread=PacketPublisher, member=3): Timeout while delivering a packet; requesting the departure confirmation for Member(Id=6, Timestamp=2010-02-26 15:27:58.635, Address=10.149.155.78:8088, MachineId=1102, Location=process:228, Role=CoherenceServer) by MemberSet(Size=2, BitSetCount=2 Member(Id=1, Timestamp=2010-02-26 15:27:06.931, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer) Member(Id=2, Timestamp=2010-02-26 15:27:17.847, Address=10.149.155.77:8088, MachineId=1101, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:296, Role=CoherenceServer) ) 2010-02-26 15:30:35.165/191.698 Oracle Coherence GE 3.5.3/465p2 <Info> (thread=Cluster, member=3): Member departure confirmed by MemberSet(Size=2, BitSetCount=2 Member(Id=1, Timestamp=2010-02-26 15:27:06.931, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer) Member(Id=2, Timestamp=2010-02-26 15:27:17.847, Address=10.149.155.77:8088, MachineId=1101, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:296, Role=CoherenceServer) ); removing Member(Id=6, Timestamp=2010-02-26 15:27:58.635, Address=10.149.155.78:8088, MachineId=1102, Location=process:228, Role=CoherenceServer) In this case, Member 3 happened to select two witnesses that it still had connectivity with (Members 1 and 2) thus resulting in a simple decision to remove Member 6. Given the departure of Member 6, Member 2 is left with a single witness to confirm the departure of Member 4: 2010-02-26 15:30:35.713/200.003 Oracle Coherence GE 3.5.3/465p2 <Info> (thread=Cluster, member=2): Member departure confirmed by MemberSet(Size=1, BitSetCount=2 Member(Id=1, Timestamp=2010-02-26 15:27:06.931, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer) ); removing Member(Id=4, Timestamp=2010-02-26 15:27:39.574, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer) In the meantime, Member 4 logs a missing heartbeat from the senior member. This message is also logged on Members 5 and 6. 2010-02-26 15:30:07.906/150.453 Oracle Coherence GE 3.5.3/465p2 <Info> (thread=PacketListenerN, member=4): Scheduled senior member heartbeat is overdue; rejoining multicast group. Next, Member 4 logs a TcpRing failure with Member 2, thus resulting in the termination of Member 2: 2010-02-26 15:30:21.421/163.968 Oracle Coherence GE 3.5.3/465p2 <D4> (thread=Cluster, member=4): TcpRing: Number of socket exceptions exceeded maximum; last was "java.net.SocketTimeoutException: connect timed out"; removing the member: 2 For quick process termination detection, Oracle Coherence utilizes a feature called TcpRing which is a sparse collection of TCP/IP-based connections between different members in the cluster. Each member in the cluster is connected to at least one other member, which (if at all possible) is running on a different physical box. This connection is not used for any data transfer, only heartbeat communications are sent once a second per each link. If a certain number of exceptions are thrown while trying to re-establish a connection, the member throwing the exceptions is removed from the cluster. Member 5 logs a packet timeout with Member 3 and cites witnesses Members 4 and 6: 2010-02-26 15:30:29.791/165.037 Oracle Coherence GE 3.5.3/465p2 <Warning> (thread=PacketPublisher, member=5): Timeout while delivering a packet; requesting the departure confirmation for Member(Id=3, Timestamp=2010-02-26 15:27:24.892, Address=10.149.155.236:8088, MachineId=1260, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:32459, Role=CoherenceServer) by MemberSet(Size=2, BitSetCount=2 Member(Id=4, Timestamp=2010-02-26 15:27:39.574, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer) Member(Id=6, Timestamp=2010-02-26 15:27:58.635, Address=10.149.155.78:8088, MachineId=1102, Location=process:228, Role=CoherenceServer) ) 2010-02-26 15:30:29.798/165.044 Oracle Coherence GE 3.5.3/465p2 <Info> (thread=Cluster, member=5): Member departure confirmed by MemberSet(Size=2, BitSetCount=2 Member(Id=4, Timestamp=2010-02-26 15:27:39.574, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer) Member(Id=6, Timestamp=2010-02-26 15:27:58.635, Address=10.149.155.78:8088, MachineId=1102, Location=process:228, Role=CoherenceServer) ); removing Member(Id=3, Timestamp=2010-02-26 15:27:24.892, Address=10.149.155.236:8088, MachineId=1260, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:32459, Role=CoherenceServer) Eventually we are left with two distinct clusters consisting of Members 1, 2, 3 and Members 4, 5, 6, respectively. In the latter cluster, Member 4 is promoted to senior member. The connection between the two switches is restored at 15:33. Upon the restoration of the connection, the cluster members immediately receive cluster heartbeats from the two senior members. In the case of Members 1, 2, and 3, the following is logged: 2010-02-26 15:33:14.970/369.066 Oracle Coherence GE 3.5.3/465p2 <Warning> (thread=Cluster, member=1): The member formerly known as Member(Id=4, Timestamp=2010-02-26 15:30:35.341, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer) has been forcefully evicted from the cluster, but continues to emit a cluster heartbeat; henceforth, the member will be shunned and its messages will be ignored. Likewise for Members 4, 5, and 6: 2010-02-26 15:33:14.343/336.890 Oracle Coherence GE 3.5.3/465p2 <Warning> (thread=Cluster, member=4): The member formerly known as Member(Id=1, Timestamp=2010-02-26 15:30:31.64, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer) has been forcefully evicted from the cluster, but continues to emit a cluster heartbeat; henceforth, the member will be shunned and its messages will be ignored. This message indicates that a senior heartbeat is being received from members that were previously removed from the cluster, in other words, something that should not be possible. For this reason, the recipients of these messages will initially ignore them. After several iterations of these messages, the existence of multiple clusters is acknowledged, thus triggering the panic protocol to reconcile this situation. When the presence of more than one cluster (i.e. Split-Brain) is detected by a Coherence member, the panic protocol is invoked in order to resolve the conflicting clusters and consolidate into a single cluster. The protocol consists of the removal of smaller clusters until there is one cluster remaining. In the case of equal size clusters, the one with the older Senior Member will survive. Member 1, being the oldest member, initiates the protocol: 2010-02-26 15:33:45.970/400.066 Oracle Coherence GE 3.5.3/465p2 <Warning> (thread=Cluster, member=1): An existence of a cluster island with senior Member(Id=4, Timestamp=2010-02-26 15:27:39.574, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer) containing 3 nodes have been detected. Since this Member(Id=1, Timestamp=2010-02-26 15:27:06.931, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer) is the senior of an older cluster island, the panic protocol is being activated to stop the other island's senior and all junior nodes that belong to it. Member 3 receives the panic: 2010-02-26 15:33:45.803/382.336 Oracle Coherence GE 3.5.3/465p2 <Error> (thread=Cluster, member=3): Received panic from senior Member(Id=1, Timestamp=2010-02-26 15:27:06.931, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer) caused by Member(Id=4, Timestamp=2010-02-26 15:27:39.574, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer) Member 4, the senior member of the younger cluster, receives the kill message from Member 3: 2010-02-26 15:33:44.921/367.468 Oracle Coherence GE 3.5.3/465p2 <Error> (thread=Cluster, member=4): Received a Kill message from a valid Member(Id=3, Timestamp=2010-02-26 15:27:24.892, Address=10.149.155.236:8088, MachineId=1260, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:32459, Role=CoherenceServer); stopping cluster service. In turn, Member 4 requests the departure of its junior members 5 and 6: 2010-02-26 15:33:44.921/367.468 Oracle Coherence GE 3.5.3/465p2 <Error> (thread=Cluster, member=4): Received a Kill message from a valid Member(Id=3, Timestamp=2010-02-26 15:27:24.892, Address=10.149.155.236:8088, MachineId=1260, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:32459, Role=CoherenceServer); stopping cluster service. 2010-02-26 15:33:43.343/349.015 Oracle Coherence GE 3.5.3/465p2 <Error> (thread=Cluster, member=6): Received a Kill message from a valid Member(Id=4, Timestamp=2010-02-26 15:27:39.574, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer); stopping cluster service. Once Members 4, 5, and 6 restart, they rejoin the original cluster with senior member 1. The log below is from Member 4. Note that it receives a different member id when it rejoins the cluster. 2010-02-26 15:33:44.921/367.468 Oracle Coherence GE 3.5.3/465p2 <Error> (thread=Cluster, member=4): Received a Kill message from a valid Member(Id=3, Timestamp=2010-02-26 15:27:24.892, Address=10.149.155.236:8088, MachineId=1260, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:32459, Role=CoherenceServer); stopping cluster service. 2010-02-26 15:33:46.921/369.468 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Cluster, member=4): Service Cluster left the cluster 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Invocation:InvocationService, member=4): Service InvocationService left the cluster 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=OptimisticCache, member=4): Service OptimisticCache left the cluster 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=ReplicatedCache, member=4): Service ReplicatedCache left the cluster 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=DistributedCache, member=4): Service DistributedCache left the cluster 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Invocation:Management, member=4): Service Management left the cluster 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Cluster, member=4): Member 6 left service Management with senior member 5 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Cluster, member=4): Member 6 left service DistributedCache with senior member 5 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Cluster, member=4): Member 6 left service ReplicatedCache with senior member 5 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Cluster, member=4): Member 6 left service OptimisticCache with senior member 5 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Cluster, member=4): Member 6 left service InvocationService with senior member 5 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Cluster, member=4): Member(Id=6, Timestamp=2010-02-26 15:33:47.046, Address=10.149.155.78:8088, MachineId=1102, Location=process:228, Role=CoherenceServer) left Cluster with senior member 4 2010-02-26 15:33:49.218/371.765 Oracle Coherence GE 3.5.3/465p2 <Info> (thread=main, member=n/a): Restarting cluster 2010-02-26 15:33:49.421/371.968 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Cluster, member=n/a): Service Cluster joined the cluster with senior service member n/a 2010-02-26 15:33:49.625/372.172 Oracle Coherence GE 3.5.3/465p2 <Info> (thread=Cluster, member=n/a): This Member(Id=5, Timestamp=2010-02-26 15:33:50.499, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer, Edition=Grid Edition, Mode=Development, CpuCount=2, SocketCount=1) joined cluster "cluster:0xDDEB" with senior Member(Id=1, Timestamp=2010-02-26 15:27:06.931, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer, Edition=Grid Edition, Mode=Development, CpuCount=2, SocketCount=2) Cool isn't it?

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• Pre-filtering and shaping OData feeds using WCF Data Services and the Entity Framework - Part 1

  - by rajbk

  The Open Data Protocol, referred to as OData, is a new data-sharing standard that breaks down silos and fosters an interoperative ecosystem for data consumers (clients) and producers (services) that is far more powerful than currently possible. It enables more applications to make sense of a broader set of data, and helps every data service and client add value to the whole ecosystem. WCF Data Services (previously known as ADO.NET Data Services), then, was the first Microsoft technology to support the Open Data Protocol in Visual Studio 2008 SP1. It provides developers with client libraries for .NET, Silverlight, AJAX, PHP and Java. Microsoft now also supports OData in SQL Server 2008 R2, Windows Azure Storage, Excel 2010 (through PowerPivot), and SharePoint 2010. Many other other applications in the works. * This post walks you through how to create an OData feed, define a shape for the data and pre-filter the data using Visual Studio 2010, WCF Data Services and the Entity Framework. A sample project is attached at the bottom of Part 2 of this post. Pre-filtering and shaping OData feeds using WCF Data Services and the Entity Framework - Part 2 Create the Web Application File –› New –› Project, Select “ASP.NET Empty Web Application” Add the Entity Data Model Right click on the Web Application in the Solution Explorer and select “Add New Item..” Select “ADO.NET Entity Data Model” under "Data”. Name the Model “Northwind” and click “Add”.   In the “Choose Model Contents”, select “Generate Model From Database” and click “Next”   Define a connection to your database containing the Northwind database in the next screen. We are going to expose the Products table through our OData feed. Select “Products” in the “Choose your Database Object” screen.   Click “Finish”. We are done creating our Entity Data Model. Save the Northwind.edmx file created. Add the WCF Data Service Right click on the Web Application in the Solution Explorer and select “Add New Item..” Select “WCF Data Service” from the list and call the service “DataService” (creative, huh?). Click “Add”.   Enable Access to the Data Service Open the DataService.svc.cs class. The class is well commented and instructs us on the next steps. public class DataService : DataService< /* TODO: put your data source class name here */ > { // This method is called only once to initialize service-wide policies. public static void InitializeService(DataServiceConfiguration config) { // TODO: set rules to indicate which entity sets and service operations are visible, updatable, etc. // Examples: // config.SetEntitySetAccessRule("MyEntityset", EntitySetRights.AllRead); // config.SetServiceOperationAccessRule("MyServiceOperation", ServiceOperationRights.All); config.DataServiceBehavior.MaxProtocolVersion = DataServiceProtocolVersion.V2; } } Replace the comment that starts with “/* TODO:” with “NorthwindEntities” (the entity container name of the Model we created earlier).  WCF Data Services is initially locked down by default, FTW! No data is exposed without you explicitly setting it. You have explicitly specify which Entity sets you wish to expose and what rights are allowed by using the SetEntitySetAccessRule. The SetServiceOperationAccessRule on the other hand sets rules for a specified operation. Let us define an access rule to expose the Products Entity we created earlier. We use the EnititySetRights.AllRead since we want to give read only access. Our modified code is shown below. public class DataService : DataService<NorthwindEntities> { public static void InitializeService(DataServiceConfiguration config) { config.SetEntitySetAccessRule("Products", EntitySetRights.AllRead); config.DataServiceBehavior.MaxProtocolVersion = DataServiceProtocolVersion.V2; } } We are done setting up our ODataFeed! Compile your project. Right click on DataService.svc and select “View in Browser” to see the OData feed. To view the feed in IE, you must make sure that "Feed Reading View" is turned off. You set this under Tools -› Internet Options -› Content tab.   If you navigate to “Products”, you should see the Products feed. Note also that URIs are case sensitive. ie. Products work but products doesn’t.   Filtering our data OData has a set of system query operations you can use to perform common operations against data exposed by the model. For example, to see only Products in CategoryID 2, we can use the following request: /DataService.svc/Products?$filter=CategoryID eq 2 At the time of this writing, supported operations are $orderby, $top, $skip, $filter, $expand, $format†, $select, $inlinecount. Pre-filtering our data using Query Interceptors The Product feed currently returns all Products. We want to change that so that it contains only Products that have not been discontinued. WCF introduces the concept of interceptors which allows us to inject custom validation/policy logic into the request/response pipeline of a WCF data service. We will use a QueryInterceptor to pre-filter the data so that it returns only Products that are not discontinued. To create a QueryInterceptor, write a method that returns an Expression<Func<T, bool>> and mark it with the QueryInterceptor attribute as shown below. [QueryInterceptor("Products")] public Expression<Func<Product, bool>> OnReadProducts() { return o => o.Discontinued == false; } Viewing the feed after compilation will only show products that have not been discontinued. We also confirm this by looking at the WHERE clause in the SQL generated by the entity framework. SELECT [Extent1].[ProductID] AS [ProductID], ... ... [Extent1].[Discontinued] AS [Discontinued] FROM [dbo].[Products] AS [Extent1] WHERE 0 = [Extent1].[Discontinued] Other examples of Query/Change interceptors can be seen here including an example to filter data based on the identity of the authenticated user. We are done pre-filtering our data. In the next part of this post, we will see how to shape our data. Pre-filtering and shaping OData feeds using WCF Data Services and the Entity Framework - Part 2 Foot Notes * http://msdn.microsoft.com/en-us/data/aa937697.aspx † $format did not work for me. The way to get a Json response is to include the following in the  request header “Accept: application/json, text/javascript, */*” when making the request. This is easily done with most JavaScript libraries.

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• Big Data Matters with ODI12c

  - by Madhu Nair

  contributed by Mike Eisterer On October 17th, 2013, Oracle announced the release of Oracle Data Integrator 12c (ODI12c).  This release signifies improvements to Oracle’s Data Integration portfolio of solutions, particularly Big Data integration. Why Big Data = Big Business Organizations are gaining greater insights and actionability through increased storage, processing and analytical benefits offered by Big Data solutions.  New technologies and frameworks like HDFS, NoSQL, Hive and MapReduce support these benefits now. As further data is collected, analytical requirements increase and the complexity of managing transformations and aggregations of data compounds and organizations are in need for scalable Data Integration solutions. ODI12c provides enterprise solutions for the movement, translation and transformation of information and data heterogeneously and in Big Data Environments through: The ability for existing ODI and SQL developers to leverage new Big Data technologies. A metadata focused approach for cataloging, defining and reusing Big Data technologies, mappings and process executions. Integration between many heterogeneous environments and technologies such as HDFS and Hive. Generation of Hive Query Language. Working with Big Data using Knowledge Modules  ODI12c provides developers with the ability to define sources and targets and visually develop mappings to effect the movement and transformation of data.  As the mappings are created, ODI12c leverages a rich library of prebuilt integrations, known as Knowledge Modules (KMs).  These KMs are contextual to the technologies and platforms to be integrated.  Steps and actions needed to manage the data integration are pre-built and configured within the KMs.  The Oracle Data Integrator Application Adapter for Hadoop provides a series of KMs, specifically designed to integrate with Big Data Technologies.  The Big Data KMs include: Check Knowledge Module Reverse Engineer Knowledge Module Hive Transform Knowledge Module Hive Control Append Knowledge Module File to Hive (LOAD DATA) Knowledge Module File-Hive to Oracle (OLH-OSCH) Knowledge Module  Nothing to beat an Example: To demonstrate the use of the KMs which are part of the ODI Application Adapter for Hadoop, a mapping may be defined to move data between files and Hive targets.  The mapping is defined by dragging the source and target into the mapping, performing the attribute (column) mapping (see Figure 1) and then selecting the KM which will govern the process.  In this mapping example, movie data is being moved from an HDFS source into a Hive table.  Some of the attributes, such as “CUSTID to custid”, have been mapped over. Figure 1  Defining the Mapping Before the proper KM can be assigned to define the technology for the mapping, it needs to be added to the ODI project.  The Big Data KMs have been made available to the project through the KM import process.   Generally, this is done prior to defining the mapping. Figure 2  Importing the Big Data Knowledge Modules Following the import, the KMs are available in the Designer Navigator. v\:* {behavior:url(#default#VML);} o\:* {behavior:url(#default#VML);} w\:* {behavior:url(#default#VML);} .shape {behavior:url(#default#VML);} Normal 0 false false false EN-US ZH-TW X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Calibri","sans-serif"; mso-bidi-font-family:"Times New Roman";} Figure 3  The Project View in Designer, Showing Installed IKMs Once the KM is imported, it may be assigned to the mapping target.  This is done by selecting the Physical View of the mapping and examining the Properties of the Target.  In this case MOVIAPP_LOG_STAGE is the target of our mapping. Figure 4  Physical View of the Mapping and Assigning the Big Data Knowledge Module to the Target Alternative KMs may have been selected as well, providing flexibility and abstracting the logical mapping from the physical implementation.  Our mapping may be applied to other technologies as well. The mapping is now complete and is ready to run.  We will see more in a future blog about running a mapping to load Hive. To complete the quick ODI for Big Data Overview, let us take a closer look at what the IKM File to Hive is doing for us.  ODI provides differentiated capabilities by defining the process and steps which normally would have to be manually developed, tested and implemented into the KM.  As shown in figure 5, the KM is preparing the Hive session, managing the Hive tables, performing the initial load from HDFS and then performing the insert into Hive.  HDFS and Hive options are selected graphically, as shown in the properties in Figure 4. Figure 5  Process and Steps Managed by the KM What’s Next Big Data being the shape shifting business challenge it is is fast evolving into the deciding factor between market leaders and others. Now that an introduction to ODI and Big Data has been provided, look for additional blogs coming soon using the Knowledge Modules which make up the Oracle Data Integrator Application Adapter for Hadoop: Importing Big Data Metadata into ODI, Testing Data Stores and Loading Hive Targets Generating Transformations using Hive Query language Loading Oracle from Hadoop Sources For more information now, please visit the Oracle Data Integrator Application Adapter for Hadoop web site, http://www.oracle.com/us/products/middleware/data-integration/hadoop/overview/index.html Do not forget to tune in to the ODI12c Executive Launch webcast on the 12th to hear more about ODI12c and GG12c. Normal 0 false false false EN-US ZH-TW X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Calibri","sans-serif"; mso-bidi-font-family:"Times New Roman";}

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• Real or False Recovery? Economic 'tea-leaves'

  - by [email protected]

  "Information-technology is allowing the city's economy to speak to us in lots of different ways," Mr. Egan said. "We just need to find new ways of listening." Source: "New Way to Read Economy" WSJ_ARTICLE  April 8th, Carli Tuna, Blog by ARC's Steve Banker Apr 12, 2010 Alan Greenspan used cardboard box purchases and other 'source-commodity' indicators. The Carli Tuna WSJ article said that truck diesel fuel sales are a reliable indicator. What factor do you and your company use as future forward indicators? .. is it quotes, perhaps calls into the call center or sales activity?  Is your business moving to the internet and your supply chain driven by your iStore?  How do your distributors, retailers and supply chain partners provide the 'side-line' signals to you to either ramp up or contract production? With competition being only one click away, organizations need to know with higher degrees of certainty, what the econmic 'tea-leaves' are telling us and how firms need to react with production and shipping forecasts.  Firms using the latest forecasting and supply chain analytical (Bus.Intelligence) tools and technologies appear to be leading their markets "Had we been aware of that data in 2008," Mr. Leamer said, "we would have made a different call." .        

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• JavaScript Data Binding Frameworks

  - by dwahlin

  Data binding is where it’s at now days when it comes to building client-centric Web applications. Developers experienced with desktop frameworks like WPF or web frameworks like ASP.NET, Silverlight, or others are used to being able to take model objects containing data and bind them to UI controls quickly and easily. When moving to client-side Web development the data binding story hasn’t been great since neither HTML nor JavaScript natively support data binding. This means that you have to write code to place data in a control and write code to extract it. Although it’s certainly feasible to do it from scratch (many of us have done it this way for years), it’s definitely tedious and not exactly the best solution when it comes to maintenance and re-use. Over the last few years several different script libraries have been released to simply the process of binding data to HTML controls. In fact, the subject of data binding is becoming so popular that it seems like a new script library is being released nearly every week. Many of the libraries provide MVC/MVVM pattern support in client-side JavaScript apps and some even integrate directly with server frameworks like Node.js. Here’s a quick list of a few of the available libraries that support data binding (if you like any others please add a comment and I’ll try to keep the list updated): AngularJS MVC framework for data binding (although closely follows the MVVM pattern). Backbone.js MVC framework with support for models, key/value binding, custom events, and more. Derby Provides a real-time environment that runs in the browser an in Node.js. The library supports data binding and templates. Ember Provides support for templates that automatically update as data changes. JsViews Data binding framework that provides “interactive data-driven views built on top of JsRender templates”. jQXB Expression Binder Lightweight jQuery plugin that supports bi-directional data binding support. KnockoutJS MVVM framework with robust support for data binding. For an excellent look at using KnockoutJS check out John Papa’s course on Pluralsight. Meteor End to end framework that uses Node.js on the server and provides support for data binding on  the client. Simpli5 JavaScript framework that provides support for two-way data binding. WinRT with HTML5/JavaScript If you’re building Windows 8 applications using HTML5 and JavaScript there’s built-in support for data binding in the WinJS library.   I won’t have time to write about each of these frameworks, but in the next post I’m going to talk about my (current) favorite when it comes to client-side JavaScript data binding libraries which is AngularJS. AngularJS provides an extremely clean way – in my opinion - to extend HTML syntax to support data binding while keeping model objects (the objects that hold the data) free from custom framework method calls or other weirdness. While I’m writing up the next post, feel free to visit the AngularJS developer guide if you’d like additional details about the API and want to get started using it.

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• Protect Data and Save Money? Learn How Best-in-Class Organizations do Both

  - by roxana.bradescu

  Databases contain nearly two-thirds of the sensitive information that must be protected as part of any organization's overall approach to security, risk management, and compliance. Solutions for protecting data housed in databases vary from encrypting data at the application level to defense-in-depth protection of the database itself. So is there a difference? Absolutely! According to new research from the Aberdeen Group, Best-in-Class organizations experience fewer data breaches and audit deficiencies - at lower cost -- by deploying database security solutions. And the results are dramatic: Aberdeen found that organizations encrypting data within their databases achieved 30% fewer data breaches and 15% greater audit efficiency with 34% less total cost when compared to organizations encrypting data within applications. Join us for a live webcast with Derek Brink, Vice President and Research Fellow at the Aberdeen Group, next week to learn how your organization can become Best-in-Class.

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• Bad Data is Really the Monster

  - by Dain C. Hansen

  Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Calibri","sans-serif"; mso-bidi-font-family:"Times New Roman";} Bad Data is really the monster – is an article written by Bikram Sinha who I borrowed the title and the inspiration for this blog. Sinha writes: “Bad or missing data makes application systems fail when they process order-level data. One of the key items in the supply-chain industry is the product (aka SKU). Therefore, it becomes the most important data element to tie up multiple merchandising processes including purchase order allocation, stock movement, shipping notifications, and inventory details… Bad data can cause huge operational failures and cost millions of dollars in terms of time, resources, and money to clean up and validate data across multiple participating systems. Yes bad data really is the monster, so what do we do about it? Close our eyes and hope it stays in the closet? We’ve tacked this problem for some years now at Oracle, and with our latest introduction of Oracle Enterprise Data Quality along with our integrated Oracle Master Data Management products provides a complete, best-in-class answer to the bad data monster. What’s unique about it? Oracle Enterprise Data Quality also combines powerful data profiling, cleansing, matching, and monitoring capabilities while offering unparalleled ease of use. What makes it unique is that it has dedicated capabilities to address the distinct challenges of both customer and product data quality – [different monsters have different needs of course!]. And the ability to profile data is just as important to identify and measure poor quality data and identify new rules and requirements. Included are semantic and pattern-based recognition to accurately parse and standardize data that is poorly structured. Finally all of the data quality components are integrated with Oracle Master Data Management, including Oracle Customer Hub and Oracle Product Hub, as well as Oracle Data Integrator Enterprise Edition and Oracle CRM. Want to learn more? On Tuesday Nov 15th, I invite you to listen to our webcast on Reduce ERP consolidation risks with Oracle Master Data Management I’ll be joined by our partner iGate Patni and be talking about one specific way to deal with the bad data monster specifically around ERP consolidation. Look forward to seeing you there!

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• Where can I locate business data to use in my application?

  - by Aaron McIver

  This question talks about any and all free public raw data which appeared to have valuable pieces but nothing that really provides what I am looking for. Instead of using a socially defined listing of businesses (foursquare), I would like a business listing data set of registered businesses and associated addresses that could then be searchable based on location (coordinates). The critical need is that the data set should be filterable based on varying criteria (give me all restaurants, coffee shops, etc...). If the data is free that is great but anywhere that sells this type of data would also suffice. Infochimps looked like a possibility but perhaps something a bit more extensive exists. Where can I find a free or for fee data set of registered business that is filterable based on type of business and location?

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• Mounting a Mail Store that is in a Recovery Storage group On Exchange 2003

  - by Kyle Brandt

  If I have a production server with the Mail Store Foo in both the storage group companyName and the Recovery Storage Group, is it okay to Mount Foo in the RSG while it is mounted in companyName so I can extract some mailboxs from the recovery storage group? Basically I am wonder if it is okay to mount it in both Production and the Recovery Storage Groups while the mail server is in production and the particular mail store is in production. Reference: "Once an RSG is restored into and mounted up you can connect to it with ExMerge and read out mailboxes into PST files for merging back into a 'live' store" -- http://serverfault.com/questions/49728/test-restore-of-exchange-dbs-with-the-ms-exchange-plugin-of-netbackup-6

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• HP Recovery Manager failed creating a backup disc

  - by Baehr

  I had to restore my computer (running Windows 7) back to its factory default, so I ran the HP recovery manager disc and chose to reformat my computer. Before doing this I was given an option to backup my current files to a DVD, and I did so; getting the confirmation of a successful DVD burn. Booting up my computer everything looks like it did when I first purchased it (like expected). But when I pop in the backup DVD and run the recovery EXE inside it, the application creates a directory inside C:\System Recovery Files which contains the empty directories: [(^_^)] and Program Data. So essentially what I'm getting out of this is a failure in creating a back-up. Which is not only confusing but incredibly frusterating. Is there any way that I can recover the files lost in the

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• Recovery files from a damage VM?

  - by ejlml

  After search and search again, my VM still can't recovery. Does somebody know how to retrieve the files from the VM? My VM is XP, it can't boot up anymore after my forced quit. In the Mac OS 10.6.2, I try to "get info" the VM file, I can see it is still using 25G space. I try to mount it with VMDK mounter (just right click the VM file and chose open with), it can mount but nothing inside. I also try to use filesalvage to recovery the files after mounted the VM, it can recovery many many files, but the files name and some document become to be symbol. What can I do now? Pls help me, thanks!

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• How likely can my data be recovered after Windows CHKDSK performed on a degraded RAID 5 array?

  - by chrisling106

  Hello there, We have a RAID 5 setup with 3 SATA disks, #2 went down as reported on the pre-POST screen. Unfortunately, for some reason out of my control, the system was rebooted with a degraded RAID :-O Windows XP (64-bit) loaded, CHKDSK ran automatically and done its recovery! From that point onwards, the following error prompts every time even in Safe Mode: lsass.exe - The endpoint format is invalid I took those 3 disks to the data recovery expert and need to wait at least 2-4 days for results. There are 2 VMs on multiple files stored in this RAID 5 array, and there's no backup! Sorry, I just inherited the system from an ex-staff who has left the company 2 months before I joined. How likely the data can be recovered?

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• Recovering data from failed Raid configuration with 4 drives and two raid sets (Asus P6T / Intel ICH10r)

  - by user56365

  I've added the complete detailed version for my question below for those who can help, but want to quickly summarize my question first. I setup two Raid arrays using (4) WD Raptors, a striped set for the OS and 1+0 set for crucial data. After booting once out of the 50 times a cable fell out, the drive wasn't recognized in the array anymore. After trying to fix it, another drive did the same. I now have two drives remaining, luckily with the parity information. I know the striped set is gone, but I need the data on the other set. Can anyone recommend anything to recover the data, or fix the two drives that doesn't allow the raid controller to recognize the drives, even though they are listed on the utility screen as still apart of the configuration but that they are not found? More Details I recently upgraded to a ASUS P6T motherboard with an Intel ICH10R raid controller and changed my previous 4 drive raid array from strictly a Raid 1+0 set to a Raid 0 for the OS/Page/Scratch drive and a Raid 1+0 set for crucial data. I never had problems after upgrading with my configuration, even when a drive died and was replaced. I managed to rebuild the array fine. Unfortunately this time around, a cable came unattached and I booted my system up until the raid status screen with the degraded error. This shouldn't have been a problem, but after I attached the drive it was no longer recognized as a member in the array. Both drives actually show up as a non-member disk. I've spent a very, very long time online trying to find information or support and haven't had much luck. After spending time trying to scan the drive for errors, damaged partition info, etc.. another drive in the set decided it didn't want to be recognized as a part of the array. At this point, I have two out of the four drives still functioning, but the Raid 1+0 array went from degraded to failed and I must find a way to retrieve that data. I think the two drives still in the array have the parity information because they show up as OS (110GB),BACKUP(80GB) and OS:1(110GB),BACKUP(80GB) under windows data management. The other two are simply 74gb Raw unallocated Is it possible recover the data using those two drive only, and which tool would I use? Could it be a simple partition table or any other error that is repairable with hard drive utilities out there? I know the Raid 0 set is done for, but I would assume because the correct drives failed in a 1+0 config to save the data I can retrieve it some how.

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• Sybase PowerDesigner Change Many (Find/Replace/Convert) Data Item's Data Types

  - by Andy

  Hello, I have a relatively large Conceptual Data Model in PowerDesigner. After generating a Physical Data Model and seeing the DBMS data types, I need to update all of data types(NUMBER/TEXT) for each data item. I'd like to either do a find/replace within the Conceptual Data Model or somehow map to different data types when creating the Physical Data Model. Ex. Change the auto conversion of Text - Clob, to Text - NVARCHAR(20). Thanks!

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• are there any useful datasets available on the web for data mining?

  - by niko

  Hi, Does anyone know any good resource where example (real) data can be downloaded for experimenting statistics and machine learning techniques such as decision trees etc? Currently I am studying machine learning techniques and it would be very helpful to have real data for evaluating the accuracy of various tools. If anyone knows any good resource (perhaps csv, xls files or any other format) I would be very thankful for a suggestion.

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• Fragmented Log files could be slowing down your database

  - by Fatherjack

  Something that is sometimes forgotten by a lot of DBAs is the fact that database log files get fragmented in the same way that you get fragmentation in a data file. The cause is very different but the effect is the same – too much effort reading and writing data. Data files get fragmented as data is changed through normal system activity, INSERTs, UPDATEs and DELETEs cause fragmentation and most experienced DBAs are monitoring their indexes for fragmentation and dealing with it accordingly. However, you don’t hear about so many working on their log files. How can a log file get fragmented? I’m glad you asked. When you create a database there are at least two files created on the disk storage; an mdf for the data and an ldf for the log file (you can also have ndf files for extra data storage but that’s off topic for now). It is wholly possible to have more than one log file but in most cases there is little point in creating more than one as the log file is written to in a ‘wrap-around’ method (more on that later). When a log file is created at the time that a database is created the file is actually sub divided into a number of virtual log files (VLFs). The number and size of these VLFs depends on the size chosen for the log file. VLFs are also created in the space added to a log file when a log file growth event takes place. Do you have your log files set to auto grow? Then you have potentially been introducing many VLFs into your log file. Let’s get to see how many VLFs we have in a brand new database. USE master GO CREATE DATABASE VLF_Test ON ( NAME = VLF_Test, FILENAME = 'C:\Program Files\Microsoft SQL Server\MSSQL10.ROCK_2008\MSSQL\DATA\VLF_Test.mdf', SIZE = 100, MAXSIZE = 500, FILEGROWTH = 50 ) LOG ON ( NAME = VLF_Test_Log, FILENAME = 'C:\Program Files\Microsoft SQL Server\MSSQL10.ROCK_2008\MSSQL\DATA\VLF_Test_log.ldf', SIZE = 5MB, MAXSIZE = 250MB, FILEGROWTH = 5MB ); go USE VLF_Test go DBCC LOGINFO; The results of this are firstly a new database is created with specified files sizes and the the DBCC LOGINFO results are returned to the script editor. The DBCC LOGINFO results have plenty of interesting information in them but lets first note there are 4 rows of information, this relates to the fact that 4 VLFs have been created in the log file. The values in the FileSize column are the sizes of each VLF in bytes, you will see that the last one to be created is slightly larger than the others. So, a 5MB log file has 4 VLFs of roughly 1.25 MB. Lets alter the CREATE DATABASE script to create a log file that’s a bit bigger and see what happens. Alter the code above so that the log file details are replaced by LOG ON ( NAME = VLF_Test_Log, FILENAME = 'C:\Program Files\Microsoft SQL Server\MSSQL10.ROCK_2008\MSSQL\DATA\VLF_Test_log.ldf', SIZE = 1GB, MAXSIZE = 25GB, FILEGROWTH = 1GB ); With a bigger log file specified we get more VLFs What if we make it bigger again? LOG ON ( NAME = VLF_Test_Log, FILENAME = 'C:\Program Files\Microsoft SQL Server\MSSQL10.ROCK_2008\MSSQL\DATA\VLF_Test_log.ldf', SIZE = 5GB, MAXSIZE = 250GB, FILEGROWTH = 5GB ); This time we see more VLFs are created within our log file. We now have our 5GB log file comprised of 16 files of 320MB each. In fact these sizes fall into all the ranges that control the VLF creation criteria – what a coincidence! The rules that are followed when a log file is created or has it’s size increased are pretty basic. If the file growth is lower than 64MB then 4 VLFs are created If the growth is between 64MB and 1GB then 8 VLFs are created If the growth is greater than 1GB then 16 VLFs are created. Now the potential for chaos comes if the default values and settings for log file growth are used. By default a database log file gets a 1MB log file with unlimited growth in steps of 10%. The database we just created is 6 MB, let’s add some data and see what happens. USE vlf_test go -- we need somewhere to put the data so, a table is in order IF OBJECT_ID('A_Table') IS NOT NULL DROP TABLE A_Table go CREATE TABLE A_Table ( Col_A int IDENTITY, Col_B CHAR(8000) ) GO -- Let's check the state of the log file -- 4 VLFs found EXECUTE ('DBCC LOGINFO'); go -- We can go ahead and insert some data and then check the state of the log file again INSERT A_Table (col_b) SELECT TOP 500 REPLICATE('a',2000) FROM sys.columns AS sc, sys.columns AS sc2 GO -- insert 500 rows and we get 22 VLFs EXECUTE ('DBCC LOGINFO'); go -- Let's insert more rows INSERT A_Table (col_b) SELECT TOP 2000 REPLICATE('a',2000) FROM sys.columns AS sc, sys.columns AS sc2 GO 10 -- insert 2000 rows, in 10 batches and we suddenly have 107 VLFs EXECUTE ('DBCC LOGINFO'); Well, that escalated quickly! Our log file is split, internally, into 107 fragments after a few thousand inserts. The same happens with any logged transactions, I just chose to illustrate this with INSERTs. Having too many VLFs can cause performance degradation at times of database start up, log backup and log restore operations so it’s well worth keeping a check on this property. How do we prevent excessive VLF creation? Creating the database with larger files and also with larger growth steps and actively choosing to grow your databases rather than leaving it to the Auto Grow event can make sure that the growths are made with a size that is optimal. How do we resolve a situation of a database with too many VLFs? This process needs to be done when the database is under little or no stress so that you don’t affect system users. The steps are: BACKUP LOG YourDBName TO YourBackupDestinationOfChoice Shrink the log file to its smallest possible size DBCC SHRINKFILE(FileNameOfTLogHere, TRUNCATEONLY) * Re-size the log file to the size you want it to, taking in to account your expected needs for the coming months or year. ALTER DATABASE YourDBName MODIFY FILE ( NAME = FileNameOfTLogHere, SIZE = TheSizeYouWantItToBeIn_MB) * – If you don’t know the file name of your log file then run sp_helpfile while you are connected to the database that you want to work on and you will get the details you need. The resize step can take quite a while This is already detailed far better than I can explain it by Kimberley Tripp in her blog 8-Steps-to-better-Transaction-Log-throughput.aspx. The result of this will be a log file with a VLF count according to the bullet list above. Knowing when VLFs are being created By complete coincidence while I have been writing this blog (it’s been quite some time from it’s inception to going live) Jonathan Kehayias from SQLSkills.com has written a great article on how to track database file growth using Event Notifications and Service Broker. I strongly recommend taking a look at it as this is going to catch any sneaky auto grows that take place and let you know about them right away. Hassle free monitoring of VLFs If you are lucky or wise enough to be using SQL Monitor or another monitoring tool that let’s you write your own custom metrics then you can keep an eye on this very easily. There is a custom metric for VLFs (written by Stuart Ainsworth) already on the site and there are some others there are very useful so take a moment or two to look around while you are there. Resources MSDN – http://msdn.microsoft.com/en-us/library/ms179355(v=sql.105).aspx Kimberly Tripp from SQLSkills.com – http://www.sqlskills.com/BLOGS/KIMBERLY/post/8-Steps-to-better-Transaction-Log-throughput.aspx Thomas LaRock at Simple-Talk.com – http://www.simple-talk.com/sql/database-administration/monitoring-sql-server-virtual-log-file-fragmentation/ Disclosure I am a Friend of Red Gate. This means that I am more than likely to say good things about Red Gate DBA and Developer tools. No matter how awesome I make them sound, take the time to compare them with other products before you contact the Red Gate sales team to make your order.

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• Big Data: Size isn’t everything

  - by Simon Elliston Ball

  Big Data has a big problem; it’s the word “Big”. These days, a quick Google search will uncover terabytes of negative opinion about the futility of relying on huge volumes of data to produce magical, meaningful insight. There are also many clichéd but correct assertions about the difficulties of correlation versus causation, in massive data sets. In reading some of these pieces, I begin to understand how climatologists must feel when people complain ironically about “global warming” during snowfall. Big Data has a name problem. There is a lot more to it than size. Shape, Speed, and…err…Veracity are also key elements (now I understand why Gartner and the gang went with V’s instead of S’s). The need to handle data of different shapes (Variety) is not new. Data developers have always had to mold strange-shaped data into our reporting systems, integrating with semi-structured sources, and even straying into full-text searching. However, what we lacked was an easy way to add semi-structured and unstructured data to our arsenal. New “Big Data” tools such as MongoDB, and other NoSQL (Not Only SQL) databases, or a graph database like Neo4J, fill this gap. Still, to many, they simply introduce noise to the clean signal that is their sensibly normalized data structures. What about speed (Velocity)? It’s not just high frequency trading that generates data faster than a single system can handle. Many other applications need to make trade-offs that traditional databases won’t, in order to cope with high data insert speeds, or to extract quickly the required information from data streams. Unfortunately, many people equate Big Data with the Hadoop platform, whose batch driven queries and job processing queues have little to do with “velocity”. StreamInsight, Esper and Tibco BusinessEvents are examples of Big Data tools designed to handle high-velocity data streams. Again, the name doesn’t do the discipline of Big Data any favors. Ultimately, though, does analyzing fast moving data produce insights as useful as the ones we get through a more considered approach, enabled by traditional BI? Finally, we have Veracity and Value. In many ways, these additions to the classic Volume, Velocity and Variety trio acknowledge the criticism that without high-quality data and genuinely valuable outputs then data, big or otherwise, is worthless. As a discipline, Big Data has recognized this, and data quality and cleaning tools are starting to appear to support it. Rather than simply decrying the irrelevance of Volume, we need as a profession to focus how to improve Veracity and Value. Perhaps we should just declare the ‘Big’ silent, embrace these new data tools and help develop better practices for their use, just as we did the good old RDBMS? What does Big Data mean to you? Which V gives your business the most pain, or the most value? Do you see these new tools as a useful addition to the BI toolbox, or are they just enabling a dangerous trend to find ghosts in the noise?

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• Cluster Node Recovery Using Second Node in Solaris Cluster

  - by Onur Bingul

  Assumptions:Node 0a is the cluster node that has crashed and could not boot anymore.Node 0b is the node in cluster and in production with services active.Both nodes have their boot disk mirrored via SDS/SVM.We have many options to clone the boot disk from node 0b:- make a copy via network using the ufsdump command and pipe to ufsrestore - make a copy inserting the disk locally on node 0b and creating the third mirror with SDS- make a copy inserting the disk locally on node 0b using dd commandIn this procedure we are going to use dd command (from my experience this is the best option).Bare in mind that in the examples provided we work on Sun Fire V240 systems which have SCSI internal disks. In the case of Fibre Channel (FC) internal disks you must pay attention to the unique identifier, or World Wide Name (WWN), associated with each FC disk (in this case take a look at infodoc #40133 in order to recreate the device tree correctly).Procedure:On node 0b the boot disk is c1t0d0 (c1t1d0 mirror) and this is the VTOC:* Partition  Tag  Flags    Sector     Count    Sector  Mount Directory      0      2    00          0   2106432   2106431      1      3    01    2106432  74630784  76737215      2      5    00          0 143349312 143349311      4      7    00   76737216  50340672 127077887      5      4    00  127077888  14683968 141761855      6      0    00  141761856   1058304 142820159      7      0    00  142820160    529152 143349311We will insert the new disk on node 0b and it will be seen as c1t2d0.1) On node 0b we make a copy via dd from disk c1t0d0s2 to disk c1t2d0s2# dd if=/dev/rdsk/c1t0d0s2 of=/dev/rdsk/c1t2d0s2 bs=8192kA copy of a 72GB disk will take approximately about 45 minutes.Note: as an alternative to make identical copy of root over network follow Document ID: 47498Title: Sun[TM] Cluster 3.0: How to Rebuild a node with Veritas Volume Manager2) Perform an fsck on disk c1t2d0 data slices:   1.  fsck -o f /dev/rdsk/c1t2d0s0 (root)   2.  fsck -o f /dev/rdsk/c1t2d0s4 (/var)   3.  fsck -o f /dev/rdsk/c1t2d0s5 (/usr)   4.  fsck -o f /dev/rdsk/c1t2d0s6 (/globaldevices)3) Mount the root file system in order to edit following files for changing the node name:# mount /dev/dsk/c1t2d0s0 /mntChange the hostname from 0b to 0a:# cd /mnt/etc# vi hosts # vi hostname.bge0 # vi hostname.bge2 # vi nodename 4) Change the /mnt/etc/vfstab from the actual:/dev/md/dsk/d201        -       -       swap    -       no      -/dev/md/dsk/d200        /dev/md/rdsk/d200       /       ufs     1       no      -/dev/md/dsk/d205        /dev/md/rdsk/d205       /usr    ufs     1       no      logging/dev/md/dsk/d204        /dev/md/rdsk/d204       /var    ufs     1       no      logging#/dev/md/dsk/d206       /dev/md/rdsk/d206       /globaldevices  ufs     2       yes     loggingswap    -       /tmp    tmpfs   -       yes     -/dev/md/dsk/d206        /dev/md/rdsk/d206       /global/.devices/node@2 ufs     2       noglobalto this (unencapsulate disk from SDS/SVM):/dev/dsk/c1t0d0s1        -       -       swap    -       no      -/dev/dsk/c1t0d0s0       /dev/rdsk/c1t0d0s0       /       ufs     1       no      -/dev/dsk/c1t0d0s5       /dev/rdsk/c1t0d0s5       /usr    ufs     1       no      logging/dev/dsk/c1t0d0s4       /dev/rdsk/c1t0d0s4       /var    ufs     1       no      logging#/dev/md/dsk/d206       /dev/md/rdsk/d206       /globaldevices  ufs     2       yes     loggingswap    -       /tmp    tmpfs   -       yes     -/dev/dsk/c1t0d0s6       /dev/rdsk/c1t0d0s6       /global/.devices/node@1 ufs     2       no globalIt is important that global device partition (slice 6) in the new vfstab will point to the physical partition of the disk (in our case slice 6).Be careful with the name you use for the new disk. In this case we define it as c1t0d0 because we will insert it as target 0 in node 0a.But this could be different based on the configuration you are working on.5) Remove following entry from /mnt/etc/system (part of unencapsulation procedure):rootdev:/pseudo/md@0:0,200,blk6) Correct the link shared -> ../../global/.devices/node@2/dev/md/shared in order to point to the nodeid of node 0a (in our case nodeid 1):# cd /mnt/dev/mdhow it is now.... node 0b has nodeid 2lrwxrwxrwx   1 root     root          42 Mar 10  2005 shared ->../../global/.devices/node@2/dev/md/shared# rm shared# ln -s ../../global/.devices/node@1/dev/md/shared sharedhow is going to be... with nodeid 1 for node 0alrwxrwxrwx   1 root     root          42 Mar 10  2005 shared ->../../global/.devices/node@1/dev/md/shared7) Change nodeid (in our case from 2 to 1):# cd /mnt/etc/cluster# vi nodeid8) Change the file /mnt/etc/path_to_inst in order to reflect the correct nodeid for node 0a:# cd /mnt/etc# vi path_to_instChange entries from node@2 to node@1 with the vi command ":%s/node@2/node@1/g"9) Write the bootblock to the disk... just in case:# /usr/sbin/installboot /usr/platform/sun4u/lib/fs/ufs/bootblk /dev/rdsk/c1t2d0s0Now the disk is ready to be inserted in node 0a in order to bootup the node.10) Bootup node 0a with command "boot -sx"... this is becasue we need to make some changes in ccr files in order to recreate did environment.11) Modify cluster ccr:# cd /etc/cluster/ccr# rm did_instances# rm did_instances.bak# vi directory - remove the did_instances line.# /usr/cluster/lib/sc/ccradm -i /etc/cluster/ccr/directory # grep ccr_gennum /etc/cluster/ccr/directory ccr_gennum -1 # /usr/cluster/lib/sc/ccradm -i /etc/cluster/ccr/infrastructure # grep ccr_gennum /etc/cluster/ccr/infrastructure ccr_gennum -112) Bring the node 0a down again to the ok prompt and then issue the command "boot -r"Now the node will join the cluster and from scstat and metaset command you can verify functionality. Next step is to encapsulate the boot disk in SDS/SVM and create the mirrors.In our case node 0b has metadevice name starting from d200. For this reason on node 0a we need to create metadevice starting from d100. This is just an example, you can have different names.The important thing to remember is that metadevice boot disks have different names on each node.13) Remove metadevice pointing to the boot and mirror disks (inherit from node 0b):# metaclear -r -f d200# metaclear -r -f d201# metaclear -r -f d204# metaclear -r -f d205# metaclear -r -f d206verify from metastat that no metadevices are set for boot and mirror disks.14) Encapsulate the boot disk:# metainit -f d110 1 1 c1t0d0s0# metainit d100 -m d110# metaroot d10015) Reboot node 0a.16) Create all the metadevice for slices remaining on boot disk# metainit -f d111 1 1 c1t0d0s1# metainit d101 -m d111# metainit -f d114 1 1 c1t0d0s4# metainit d104 -m d114# metainit -f d115 1 1 c1t0d0s5# metainit d105 -m d115# metainit -f d116 1 1 c1t0d0s6# metainit d106 -m d11617) Edit the vfstab in order to specifiy metadevices created:old:/dev/dsk/c1t0d0s1        -       -       swap    -       no      -/dev/md/dsk/d100        /dev/md/rdsk/d100       /       ufs     1       no      -/dev/dsk/c1t0d0s5       /dev/rdsk/c1t0d0s5       /usr    ufs     1       no      logging/dev/dsk/c1t0d0s4       /dev/rdsk/c1t0d0s4       /var    ufs     1       no      logging#/dev/md/dsk/d206       /dev/md/rdsk/d206       /globaldevices  ufs     2       yes     loggingswap    -       /tmp    tmpfs   -       yes     -/dev/dsk/c1t0d0s6       /dev/rdsk/c1t0d0s6       /global/.devices/node@1 ufs      2       no  globalnew:/dev/md/dsk/d101        -       -       swap    -       no      -/dev/md/dsk/d100        /dev/md/rdsk/d100       /       ufs     1       no      -/dev/md/dsk/d105        /dev/md/rdsk/d105       /usr    ufs     1       no      logging/dev/md/dsk/d104        /dev/md/rdsk/d104       /var    ufs     1       no      logging#/dev/md/dsk/106       /dev/md/rdsk/d106       /globaldevices  ufs     2       yes     loggingswap    -       /tmp    tmpfs   -       yes     -/dev/md/dsk/d106        /dev/md/rdsk/d106       /global/.devices/node@1 ufs     2       noglobal18) Reboot node 0a in order to check new SDS/SVM boot configuration.19) Label the mirror disk c1t1d0 with the VTOC of boot disk c1t0d0:# prtvtoc /dev/dsk/c1t0d0s2 > /var/tmp/VTOC_c1t0d0 # fmthard -s /var/tmp/VTOC_c1t0d0 /dev/rdsk/c1t1d0s220) Put DB replica on slice 7 of disk c1t1d0:# metadb -a -c 3 /dev/dsk/c1t1d0s721) Create metadevice for mirror disk c1t1d0 and attach the new mirror side:# metainit d120 1 1 c1t1d0s0# metattach d100 d120# metainit d121 1 1 c1t1d0s1# metattach d101 d121# metainit d124 1 1 c1t1d0s4# metattach d104 d124# metainit d125 1 1 c1t1d0s5# metattach d105 d125# metainit d126 1 1 c1t1d0s6# metattach d106 d126

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