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  • Clever recording using AVFoundation

    - by martin
    Hello I am working on my master thesis and I am programming app for iOS using AVFoundation framework. I can make by myself session and attach devices to it and record video with sound. The main problem is that I need continous recording (3hours or longer). After three hours user will stop recording and user will choose time eg. 15 mins (max 30 mins) and only this last 15 mins will be stored to iphone memory. Is it possible to 'cut' video while recording or should I record it eg. in 10 minutes block and then delete old video segments and last two segments connect to one bigger? Will perform these connections (stop recording, start new recording and then connect these two segments) lags in final long video segment? Is there any way to perform this 'clever' recording? Thank you for any ideas.

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  • Log a user in to an ASP.net application using Windows Authentication without using Windows Authentic

    - by Rising Star
    I have an ASP.net application I'm developing authentication for. I am using an existing cookie-based log on system to log users in to the system. The application runs as an anonymous account and then checks the cookie when the user wants to do something restricted. This is working fine. However, there is one caveat: I've been told that for each page that connects to our SQL server, I need to make it so that the user connects using an Active Directory account. because the system I'm using is cookie based, the user isn't logged in to Active Directory. Therefore, I use impersonation to connect to the server as a specific account. However, the powers that be here don't like impersonation; they say that it clutters up the code. I agree, but I've found no way around this. It seems that the only way that a user can be logged in to an ASP.net application is by either connecting with Internet Explorer from a machine where the user is logged in with their Active Directory account or by typing an Active Directory username and password. Neither of these two are workable in my application. I think it would be nice if I could make it so that when a user logs in and receives the cookie (which actually comes from a separate log on application, by the way), there could be some code run which tells the application to perform all network operations as the user's Active Directory account, just as if they had typed an Active Directory username and password. It seems like this ought to be possible somehow, but the solution evades me. How can I make this work? Update To those who have responded so far, I apologize for the confusion I have caused. The responses I've received indicate that you've misunderstood the question, so please allow me to clarify. I have no control over the requirement that users must perform network operations (such as SQL queries) using Active Directory accounts. I've been told several times (online and in meat-space) that this is an unusual requirement and possibly bad practice. I also have no control over the requirement that users must log in using the existing cookie-based log on application. I understand that in an ideal MS ecosystem, I would simply dis-allow anonymous access in my IIS settings and users would log in using Windows Authentication. This is not the case. The current system is that as far as IIS is concerned, the user logs in anonymously (even though they supply credentials which result in the issuance of a cookie) and we must programmatically check the cookie to see if the user has access to any restricted resources. In times past, we have simply used a single SQL account to perform all queries. My direct supervisor (who has many years of experience with this sort of thing) wants to change this. He says that if each user has his own AD account to perform SQL queries, it gives us more of a trail to follow if someone tries to do something wrong. The closest thing I've managed to come up with is using WIF to give the user a claim to a specific Active Directory account, but I still have to use impersonation because even still, the ASP.net process presents anonymous credentials to the SQL server. It boils down to this: Can I log users in with Active Directory accounts in my ASP.net application without having the users manually enter their AD credentials? (Windows Authentication)

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  • Using Supervisord, how can I start a brand new worker via supervisorctl without restarting other workers?

    - by cballou
    Let's say I have a number of existing workers running in supervisord. I want to add a new worker to the group as well as start the new worker. I perform the following steps: I modify the file /etc/supervisor/supervisord.conf and add the new worker config Back on the command line, I enter sudo supervisorctl I run reread to read the new configuration file settings. Attempting to run start workers:exampleWorkerName gives the error workers:"exampleWorkerName": ERROR (no such process) So, my question is, how can I start this new worker process without affecting my other existing workers? I'd rather not perform a supervisorctl reload or /etc/init.d/supervisord restart command.

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  • How to Reinstalling MSSQL Server 2008 with SP1? (Windows 7)

    - by user23884
    I am using Windows 7 Ultimate x64. I had earlier installed SQL server 2008 with SP1 with Visual Studio 2008 Team System with sp1. Now that VS2010 is out I wanted to install it so I uninstalled visual studio then MSSLQ Server 2008 SP1 and then SQL Server 2008 as suggested here: h**p://mark.michaelis.net/Blog/SQLServer2008InstallNightmare.aspx But now when I try to reinstall it I am unable to get it right I am getting the ERROR: “Attempted to perform an unauthorized operation.” (Following is part of the log file): 2010-04-16 04:54:57 Slp: Sco: Attempting to replace account with sid in security descriptor D:(A;CI;KR;;;S-1-5-21-2213424280-2581054173-1939225444-1027) 2010-04-16 04:54:57 Slp: ReplaceAccountWithSidInSddl -- SDDL to be processed: D:(A;CI;KR;;;S-1-5-21-2213424280-2581054173-1939225444-1027) 2010-04-16 04:54:57 Slp: ReplaceAccountWithSidInSddl -- SDDL to be returned: D:(A;CI;KR;;;S-1-5-21-2213424280-2581054173-1939225444-1027) 2010-04-16 04:54:57 Slp: Prompting user if they want to retry this action due to the following failure: 2010-04-16 04:54:57 Slp: ---------------------------------------- 2010-04-16 04:54:57 Slp: The following is an exception stack listing the exceptions in outermost to innermost order 2010-04-16 04:54:57 Slp: Inner exceptions are being indented 2010-04-16 04:54:57 Slp: 2010-04-16 04:54:57 Slp: Exception type: Microsoft.SqlServer.Configuration.Sco.ScoException 2010-04-16 04:54:57 Slp: Message: 2010-04-16 04:54:57 Slp: Attempted to perform an unauthorized operation. 2010-04-16 04:54:57 Slp: Data: 2010-04-16 04:54:57 Slp: WatsonData = Microsoft SQL Server 2010-04-16 04:54:57 Slp: DisableRetry = true 2010-04-16 04:54:57 Slp: Inner exception type: System.UnauthorizedAccessException 2010-04-16 04:54:57 Slp: Message: 2010-04-16 04:54:57 Slp: Attempted to perform an unauthorized operation. 2010-04-16 04:54:57 Slp: Stack: 2010-04-16 04:54:57 Slp: at System.Security.AccessControl.Win32.GetSecurityInfo(ResourceType resourceType, String name, SafeHandle handle, AccessControlSections accessControlSections, RawSecurityDescriptor& resultSd) 2010-04-16 04:54:57 Slp: at System.Security.AccessControl.NativeObjectSecurity.CreateInternal(ResourceType resourceType, Boolean isContainer, String name, SafeHandle handle, AccessControlSections includeSections, Boolean createByName, ExceptionFromErrorCode exceptionFromErrorCode, Object exceptionContext) 2010-04-16 04:54:57 Slp: at Microsoft.SqlServer.Configuration.Sco.SqlRegistrySecurity..ctor(ResourceType resourceType, SafeRegistryHandle handle, AccessControlSections includeSections) 2010-04-16 04:54:57 Slp: at Microsoft.SqlServer.Configuration.Sco.SqlRegistrySecurity.Create(InternalRegistryKey key) 2010-04-16 04:54:57 Slp: at Microsoft.SqlServer.Configuration.Sco.InternalRegistryKey.SetSecurityDescriptor(String sddl, Boolean overwrite) 2010-04-16 04:54:57 Slp: ---------------------------------------- 2010-04-16 10:37:19 Slp: User has chosen to cancel this action 2010-04-16 10:37:19 Slp: Watson Bucket 2 Original Parameter Values 2010-04-16 10:37:19 Slp: Parameter 0 : SQL2008@RTM@ 2010-04-16 10:37:19 Slp: Parameter 2 : System.Security.AccessControl.Win32.GetSecurityInfo 2010-04-16 10:37:19 Slp: Parameter 3 : Microsoft.SqlServer.Configuration.Sco.ScoException@1211@1 2010-04-16 10:37:19 Slp: Parameter 4 : System.UnauthorizedAccessException@-2147024891 2010-04-16 10:37:19 Slp: Parameter 5 : SqlBrowserConfigAction_install_ConfigNonRC 2010-04-16 10:37:19 Slp: Parameter 7 : Microsoft SQL Server 2010-04-16 10:37:19 Slp: Parameter 8 : Microsoft SQL Server 2010-04-16 10:37:19 Slp: Final Parameter Values I have googled around for the error given error but all I could find is to regedit and reset permissions on certain reg keys but I don’t see any reg keys with access problem in the log file the log file can be download here: http://www.mediafire.com/?dznizytjznn. Please guys help me out here I am a developer and I cannot afford an OS reinstallation! Thanks in advance…

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  • Lookup Active Directory entry by implicit UPN

    - by Michael-O
    In our company exists a forest-wide UPN suffix company.com and almost all user accounts have the explicit UPN set to [email protected]. This value is also set in the Active Directory userPrincipalName attribute. Now we have an application where users perform authentication through Kerberos. So we are given the Kerberos principal, i.e. implicit UPN. We'd like to look up that user and retrieve several LDAP attributes. Since iUPN and userPrincipalName do not match anymore, the lookup is not possible. Is there any "official" way to retrieve a mapping from the Active Direcory? My workaround is to perform a LDAP bind against the realm component and search for the sAMAccountName attribute which matches the user id component of the iUPN. Searching for the mere sAMAccountName in the forest is not possible because the value is unique in the domain only.

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  • Distributed Nagios Installation

    - by kruczkowski
    I'm looking for a plug-in or product that will act as a remote probe and perform tests then send back the results to the central Nagios server. Reason for this is that I'd like to monitor internal systems and servers at customers, but don't want to allow all the traffic passing the firewalls. Ideally I'd like a soft-probe that would be installed and then perform the tests and send back the results (via SSH) to the central Nagios installation. Does anyone know of a product or plug-in that would offer such service? If not Nagios, is there any other monitoring system that does such a thing (ideally open-source)?

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  • How to prevent Windows Home server waking for backup

    - by Andronicus
    Since changing the motherboard in my Windows home server it has been switching itself on every night to perform a scheduled backup. I don't want this to happen though, I want to switch the server on using Wake on lan, but I want to manually perform backups if/when required. I know I can disable backups of each computer, and the machine wont turn on, but I want to allow manually triggered backups, or automatic backups if the homeserver is on, but if its in sleep mode, I wish it to stay in that state unless I wake it. How can this be achieved?

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  • Unable to copy and paste (or cut and paste) photos already reduced in size from Word document into a

    - by Simon Child
    Hello I cannot copy photos and paste them from a word document into the text of an email on my Sony Laptop having already substantially redcued the size of the photos using Microsoft Office Picture Manager. I can readily manage to perform this functjon from my work place PC but am presently working mostly from home. I am trying to email photos and text using a btinternet.com email address but have checked that I cannot perform the task using my alternate googlemail email address either. I can obviously highlight the relevant photographs but whenever I try to copy or cut them into the email text the paste function is disabled. Assistance would be much appreciated. Kind regards Simon

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  • apache - subdomains are slower?

    - by matthewsteiner
    Using apache benchmark, I ran the exact same php application at my root domain and a subdomain. Even with multiple tests and high request numbers, the requests per second perform extremely differently. I mean something like this: example.com - 1200 requests per second bench.example.com - 50 requests per second What could be affecting this? These aren't using databases or anything, just mainly getting a simple page displaying. But it's the same app for both of them, and I'm wondering why they perform so differently. Ideas?

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  • Database backup regardless of backup made through a control panel?

    - by developer
    I know that all CMS or CMC platforms have some sort of walkthrough for their users to fully backup and restore the database or the whole website. While we all can perform such backups (and there are even plugins which automate the whole procedure) and restore them in necessity (such as when we migrate to a new server), one can also backup the whole website by means of such control panels as Directadmin or Cpanel. Now, I just want to know if it is necessary for us to do database or website backups the way they are described by a specific CMC or CMS developer even after we perform a whole website backup in a control panel such as DA? An example of such CMS platforms is moodle. Moodle Docs describes how we can backup and restore moodle in here. So do we, out of necessity, have to make the backup the way described, or we can simply do it the Control panel way? Thanks

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  • Ubuntu apt-get install (--download-only) executed from another machine on behalf of mine

    - by Maroloccio
    I have a server on a network segment with no direct or indirect access to the Internet. I want to perform an: apt-get install <package_name> Is there a way to somehow delegate the process of downloading the required files to another machine by exporting the server configuration so as to satisfy all dependencies while running: apt-get install --download-only <package_name> Can, in effect, apt-get install read a configuration from an exported archive rather than from the local package database? Can the list of packages to be downloaded be retrieved, along with an installation script to perform the installation, instead of the actual packages? (a further level of indirection which would help me schedule this with wget at appropriate times...)

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  • Printing Booklet Page Size in Adobe Reader 4-in-1

    - by Justin Nathanael Waters
    So I have a 70 page pdf document that I'm trying to condense to a small booklet. I tried creating a formula to manually to perform it but it got ugly fast. 35,36,34,37,17,54,16,55,33,38,32,39,15,56,14,57,31,40,30,41,13,58,12,59 29,42,28,43,11,60,10,61,27,44,26,45,9,62,8,63,25,46,24,47,7,64,6,65 23,48,22,49,5,66,4,67,21,50,20,51,3,68,2,69,19,52,18,53,1,70 Once I print the booklet I should be able to cut the sheets in half and set the bottom half behind the top and staple it for a simple book. Which means Page 1 should have pages 35,36,17,54,34,37,16,55 Page 2 should have pages 33,38,15,56,32,39,14,57 And several pages later Page 9 should have pages 19,52,1,70,18,53 But manually doing this is a headache and it seems like the booklet function should contain functionality that can perform this. I'm using a commercial Konica Minolta C452

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  • Hyper-V R2 as a VM on another virtual OS

    - by Tim
    I am trying to perform Microsoft Platform testing for a vendor application. The problem I have is that it requires the test be done on Windows Server 2008 as a VM on Hyper-V R2. Currently, I have access to a virtual server with just Hyper-V and also have access to an ESXi server. The crazy idea (which may just show how little I know about how virtualization technology works) is to install Hyper-V R2 as a VM onto one of these other servers. Then create a VM for Windows Server 2008 on this Hyper-V R2 VM. I can not just upgrade the current Hyper-V server as the VMs currently running would need to be taken off-line and are system critical (and I don't have rights to perform this upgrade). Has anyone tried this? Will this even work?

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  • ruby on rails server is intermittently slow

    - by Richard
    My rails installation was chugging along nicely. Last night we had to perform a hot-patch with was really a standard deploy of some exception code. Once capistrano finished the operation one of our admins discovered that there were two long running passenger processes. While we have deployed release over the past two weeks it would appear that these processes have been here and alive the whole time. Granted they could have been zombies or any other artifact and at this point we do not know what state they were in. Which leads me to the question: There are so many moving parts between the rails application and the OS/hardware that being a SME is probably no longer possible. So; how does a sysadmin perform root-cause analysis with any certainty? And: When do I just start rebooting servers?

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  • Forward Request to Multiple Servers

    - by cactuarz
    We have 2 servers. One is old server and another is the new one. Currently we about doing a migration because the old server is not capable enough to handle everyday requests. The specs are: Old server Ubuntu 10.04 Nginx as Reverse Proxy Apache WSGI Python/Django New Server Ubuntu 10.04 Nginx Gunicorn Python/Django Celery+Redis Our manager asked us to research if the old server can perform multiple forwarding to all incoming request, for example, set Nginx of old server to forward all request to both old and new server. The purpose is to perform unit testing to new server using old server as comparer, see if the new server is ready to take over the role. Please help, if there is an idea, or must install some engine, or what we do is impossible. Many thanks.

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  • Eclipse style autohotkey commands

    - by Ph4g3
    Is autohotkey capable of interpreting hotkeys in the style of Ctrl + Shift + W, W? I would assume a script like the following would work: ^+W:: ; Windows hotkeys (Ctrl + Shift + W) O:: Run Outlook ; Subsequent 'o' pressed => Run outlook E:: Run Explorer ; return From the documentation I note that these are called vertically stacked hotkeys and cause each line to perform the same action. In the case above, I think Ctrl+Shift+W and o will both cause outlook to be launched, whereas pressing e would cause explorer to be launched. What I would like is Ctrl+Shift+W, O runs outlook and Ctrl+Shift+W, e runs windows explorer. Is there any way to cause a hotkey to perform context specific actions (much like in Eclipse), where I can press Ctrl+Shift+W to activate a block of specific hotkeys?

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  • How come Core i7 (desktop) dominates Xeon (server)?

    - by grant tailor
    I have been using this performance benchmark results to select what CPUs to use on my web server and to my surprise, looks like Core i7 CPUs dominates the list pushing Xeon CPUs into the bush. Why is this? Why is Intel making the Core i7 perform better than the Xeon. Are Desktop CPUs supposed to perform better than server grade Xeon CPUs? I really don't get this and will like to know what you think or why this is so. Also I am thinking about getting a new web server and thinking between the i7-2600 VS the Xeon E3-1245. The i7-2600 is higher up in the performance benchmark but I am thinking the Xeon E3-1245 is server grade. What do you guys think? Should I go for the i7-2600? Or is the Xeon E3-1245 a server grade CPU for a reason?

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  • How come i7 (desktop) dominates Xeon (server)?

    - by grant tailor
    I have been using this performance benchmark results http://www.cpubenchmark.net/high_end_cpus.html to select what CPUs to use on my web server and to my surprise...looks like i7 CPUs dominates the list pushing Xeon CPUs into the bush. Why is this? Why is Intel making the i7 perform better than the Xeon. Are Desktop CPUs supposed to perform better than server grade Xeon CPUs? I really don't get this and will like to know what you think or why this is so. Also i am thinking about getting a new web server and thinking between the i7-2600 VS the Xeon E3-1245. The i7-2600 is higher up in the performance benchmark but i am thinking the Xeon E3-1245 is server grade...so what do you guys think? Should i go for the i7-2600? Or is the Xeon E3-1245 a server grade CPU for a reason?

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  • Parallelism in .NET – Part 4, Imperative Data Parallelism: Aggregation

    - by Reed
    In the article on simple data parallelism, I described how to perform an operation on an entire collection of elements in parallel.  Often, this is not adequate, as the parallel operation is going to be performing some form of aggregation. Simple examples of this might include taking the sum of the results of processing a function on each element in the collection, or finding the minimum of the collection given some criteria.  This can be done using the techniques described in simple data parallelism, however, special care needs to be taken into account to synchronize the shared data appropriately.  The Task Parallel Library has tools to assist in this synchronization. The main issue with aggregation when parallelizing a routine is that you need to handle synchronization of data.  Since multiple threads will need to write to a shared portion of data.  Suppose, for example, that we wanted to parallelize a simple loop that looked for the minimum value within a dataset: double min = double.MaxValue; foreach(var item in collection) { double value = item.PerformComputation(); min = System.Math.Min(min, value); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } This seems like a good candidate for parallelization, but there is a problem here.  If we just wrap this into a call to Parallel.ForEach, we’ll introduce a critical race condition, and get the wrong answer.  Let’s look at what happens here: // Buggy code! Do not use! double min = double.MaxValue; Parallel.ForEach(collection, item => { double value = item.PerformComputation(); min = System.Math.Min(min, value); }); This code has a fatal flaw: min will be checked, then set, by multiple threads simultaneously.  Two threads may perform the check at the same time, and set the wrong value for min.  Say we get a value of 1 in thread 1, and a value of 2 in thread 2, and these two elements are the first two to run.  If both hit the min check line at the same time, both will determine that min should change, to 1 and 2 respectively.  If element 1 happens to set the variable first, then element 2 sets the min variable, we’ll detect a min value of 2 instead of 1.  This can lead to wrong answers. Unfortunately, fixing this, with the Parallel.ForEach call we’re using, would require adding locking.  We would need to rewrite this like: // Safe, but slow double min = double.MaxValue; // Make a "lock" object object syncObject = new object(); Parallel.ForEach(collection, item => { double value = item.PerformComputation(); lock(syncObject) min = System.Math.Min(min, value); }); This will potentially add a huge amount of overhead to our calculation.  Since we can potentially block while waiting on the lock for every single iteration, we will most likely slow this down to where it is actually quite a bit slower than our serial implementation.  The problem is the lock statement – any time you use lock(object), you’re almost assuring reduced performance in a parallel situation.  This leads to two observations I’ll make: When parallelizing a routine, try to avoid locks. That being said: Always add any and all required synchronization to avoid race conditions. These two observations tend to be opposing forces – we often need to synchronize our algorithms, but we also want to avoid the synchronization when possible.  Looking at our routine, there is no way to directly avoid this lock, since each element is potentially being run on a separate thread, and this lock is necessary in order for our routine to function correctly every time. However, this isn’t the only way to design this routine to implement this algorithm.  Realize that, although our collection may have thousands or even millions of elements, we have a limited number of Processing Elements (PE).  Processing Element is the standard term for a hardware element which can process and execute instructions.  This typically is a core in your processor, but many modern systems have multiple hardware execution threads per core.  The Task Parallel Library will not execute the work for each item in the collection as a separate work item. Instead, when Parallel.ForEach executes, it will partition the collection into larger “chunks” which get processed on different threads via the ThreadPool.  This helps reduce the threading overhead, and help the overall speed.  In general, the Parallel class will only use one thread per PE in the system. Given the fact that there are typically fewer threads than work items, we can rethink our algorithm design.  We can parallelize our algorithm more effectively by approaching it differently.  Because the basic aggregation we are doing here (Min) is communitive, we do not need to perform this in a given order.  We knew this to be true already – otherwise, we wouldn’t have been able to parallelize this routine in the first place.  With this in mind, we can treat each thread’s work independently, allowing each thread to serially process many elements with no locking, then, after all the threads are complete, “merge” together the results. This can be accomplished via a different set of overloads in the Parallel class: Parallel.ForEach<TSource,TLocal>.  The idea behind these overloads is to allow each thread to begin by initializing some local state (TLocal).  The thread will then process an entire set of items in the source collection, providing that state to the delegate which processes an individual item.  Finally, at the end, a separate delegate is run which allows you to handle merging that local state into your final results. To rewriting our routine using Parallel.ForEach<TSource,TLocal>, we need to provide three delegates instead of one.  The most basic version of this function is declared as: public static ParallelLoopResult ForEach<TSource, TLocal>( IEnumerable<TSource> source, Func<TLocal> localInit, Func<TSource, ParallelLoopState, TLocal, TLocal> body, Action<TLocal> localFinally ) The first delegate (the localInit argument) is defined as Func<TLocal>.  This delegate initializes our local state.  It should return some object we can use to track the results of a single thread’s operations. The second delegate (the body argument) is where our main processing occurs, although now, instead of being an Action<T>, we actually provide a Func<TSource, ParallelLoopState, TLocal, TLocal> delegate.  This delegate will receive three arguments: our original element from the collection (TSource), a ParallelLoopState which we can use for early termination, and the instance of our local state we created (TLocal).  It should do whatever processing you wish to occur per element, then return the value of the local state after processing is completed. The third delegate (the localFinally argument) is defined as Action<TLocal>.  This delegate is passed our local state after it’s been processed by all of the elements this thread will handle.  This is where you can merge your final results together.  This may require synchronization, but now, instead of synchronizing once per element (potentially millions of times), you’ll only have to synchronize once per thread, which is an ideal situation. Now that I’ve explained how this works, lets look at the code: // Safe, and fast! double min = double.MaxValue; // Make a "lock" object object syncObject = new object(); Parallel.ForEach( collection, // First, we provide a local state initialization delegate. () => double.MaxValue, // Next, we supply the body, which takes the original item, loop state, // and local state, and returns a new local state (item, loopState, localState) => { double value = item.PerformComputation(); return System.Math.Min(localState, value); }, // Finally, we provide an Action<TLocal>, to "merge" results together localState => { // This requires locking, but it's only once per used thread lock(syncObj) min = System.Math.Min(min, localState); } ); Although this is a bit more complicated than the previous version, it is now both thread-safe, and has minimal locking.  This same approach can be used by Parallel.For, although now, it’s Parallel.For<TLocal>.  When working with Parallel.For<TLocal>, you use the same triplet of delegates, with the same purpose and results. Also, many times, you can completely avoid locking by using a method of the Interlocked class to perform the final aggregation in an atomic operation.  The MSDN example demonstrating this same technique using Parallel.For uses the Interlocked class instead of a lock, since they are doing a sum operation on a long variable, which is possible via Interlocked.Add. By taking advantage of local state, we can use the Parallel class methods to parallelize algorithms such as aggregation, which, at first, may seem like poor candidates for parallelization.  Doing so requires careful consideration, and often requires a slight redesign of the algorithm, but the performance gains can be significant if handled in a way to avoid excessive synchronization.

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  • HTML5 Form Validation

    - by Stephen.Walther
    The latest versions of Google Chrome (16+), Mozilla Firefox (8+), and Internet Explorer (10+) all support HTML5 client-side validation. It is time to take HTML5 validation seriously. The purpose of the blog post is to describe how you can take advantage of HTML5 client-side validation regardless of the type of application that you are building. You learn how to use the HTML5 validation attributes, how to perform custom validation using the JavaScript validation constraint API, and how to simulate HTML5 validation on older browsers by taking advantage of a jQuery plugin. Finally, we discuss the security issues related to using client-side validation. Using Client-Side Validation Attributes The HTML5 specification discusses several attributes which you can use with INPUT elements to perform client-side validation including the required, pattern, min, max, step, and maxlength attributes. For example, you use the required attribute to require a user to enter a value for an INPUT element. The following form demonstrates how you can make the firstName and lastName form fields required: <!DOCTYPE html> <html > <head> <title>Required Demo</title> </head> <body> <form> <label> First Name: <input required title="First Name is Required!" /> </label> <label> Last Name: <input required title="Last Name is Required!" /> </label> <button>Register</button> </form> </body> </html> If you attempt to submit this form without entering a value for firstName or lastName then you get the validation error message: Notice that the value of the title attribute is used to display the validation error message “First Name is Required!”. The title attribute does not work this way with the current version of Firefox. If you want to display a custom validation error message with Firefox then you need to include an x-moz-errormessage attribute like this: <input required title="First Name is Required!" x-moz-errormessage="First Name is Required!" /> The pattern attribute enables you to validate the value of an INPUT element against a regular expression. For example, the following form includes a social security number field which includes a pattern attribute: <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Pattern</title> </head> <body> <form> <label> Social Security Number: <input required pattern="^d{3}-d{2}-d{4}$" title="###-##-####" /> </label> <button>Register</button> </form> </body> </html> The regular expression in the form above requires the social security number to match the pattern ###-##-####: Notice that the input field includes both a pattern and a required validation attribute. If you don’t enter a value then the regular expression is never triggered. You need to include the required attribute to force a user to enter a value and cause the value to be validated against the regular expression. Custom Validation You can take advantage of the HTML5 constraint validation API to perform custom validation. You can perform any custom validation that you need. The only requirement is that you write a JavaScript function. For example, when booking a hotel room, you might want to validate that the Arrival Date is in the future instead of the past: <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Constraint Validation API</title> </head> <body> <form> <label> Arrival Date: <input id="arrivalDate" type="date" required /> </label> <button>Submit Reservation</button> </form> <script type="text/javascript"> var arrivalDate = document.getElementById("arrivalDate"); arrivalDate.addEventListener("input", function() { var value = new Date(arrivalDate.value); if (value < new Date()) { arrivalDate.setCustomValidity("Arrival date must be after now!"); } else { arrivalDate.setCustomValidity(""); } }); </script> </body> </html> The form above contains an input field named arrivalDate. Entering a value into the arrivalDate field triggers the input event. The JavaScript code adds an event listener for the input event and checks whether the date entered is greater than the current date. If validation fails then the validation error message “Arrival date must be after now!” is assigned to the arrivalDate input field by calling the setCustomValidity() method of the validation constraint API. Otherwise, the validation error message is cleared by calling setCustomValidity() with an empty string. HTML5 Validation and Older Browsers But what about older browsers? For example, what about Apple Safari and versions of Microsoft Internet Explorer older than Internet Explorer 10? What the world really needs is a jQuery plugin which provides backwards compatibility for the HTML5 validation attributes. If a browser supports the HTML5 validation attributes then the plugin would do nothing. Otherwise, the plugin would add support for the attributes. Unfortunately, as far as I know, this plugin does not exist. I have not been able to find any plugin which supports both the required and pattern attributes for older browsers, but does not get in the way of these attributes in the case of newer browsers. There are several jQuery plugins which provide partial support for the HTML5 validation attributes including: · jQuery Validation — http://docs.jquery.com/Plugins/Validation · html5Form — http://www.matiasmancini.com.ar/jquery-plugin-ajax-form-validation-html5.html · h5Validate — http://ericleads.com/h5validate/ The jQuery Validation plugin – the most popular JavaScript validation library – supports the HTML5 required attribute, but it does not support the HTML5 pattern attribute. Likewise, the html5Form plugin does not support the pattern attribute. The h5Validate plugin provides the best support for the HTML5 validation attributes. The following page illustrates how this plugin supports both the required and pattern attributes: <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>h5Validate</title> <style type="text/css"> .validationError { border: solid 2px red; } .validationValid { border: solid 2px green; } </style> </head> <body> <form id="customerForm"> <label> First Name: <input id="firstName" required /> </label> <label> Social Security Number: <input id="ssn" required pattern="^d{3}-d{2}-d{4}$" title="Expected pattern is ###-##-####" /> </label> <input type="submit" /> </form> <script type="text/javascript" src="Scripts/jquery-1.4.4.min.js"></script> <script type="text/javascript" src="Scripts/jquery.h5validate.js"></script> <script type="text/javascript"> // Enable h5Validate plugin $("#customerForm").h5Validate({ errorClass: "validationError", validClass: "validationValid" }); // Prevent form submission when errors $("#customerForm").submit(function (evt) { if ($("#customerForm").h5Validate("allValid") === false) { evt.preventDefault(); } }); </script> </body> </html> When an input field fails validation, the validationError CSS class is applied to the field and the field appears with a red border. When an input field passes validation, the validationValid CSS class is applied to the field and the field appears with a green border. From the perspective of HTML5 validation, the h5Validate plugin is the best of the plugins. It adds support for the required and pattern attributes to browsers which do not natively support these attributes such as IE9. However, this plugin does not include everything in my wish list for a perfect HTML5 validation plugin. Here’s my wish list for the perfect back compat HTML5 validation plugin: 1. The plugin would disable itself when used with a browser which natively supports HTML5 validation attributes. The plugin should not be too greedy – it should not handle validation when a browser could do the work itself. 2. The plugin should simulate the same user interface for displaying validation error messages as the user interface displayed by browsers which natively support HTML5 validation. Chrome, Firefox, and Internet Explorer all display validation errors in a popup. The perfect plugin would also display a popup. 3. Finally, the plugin would add support for the setCustomValidity() method and the other methods of the HTML5 validation constraint API. That way, you could implement custom validation in a standards compatible way and you would know that it worked across all browsers both old and new. Security It would be irresponsible of me to end this blog post without mentioning the issue of security. It is important to remember that any client-side validation — including HTML5 validation — can be bypassed. You should use client-side validation with the intention to create a better user experience. Client validation is great for providing a user with immediate feedback when the user is in the process of completing a form. However, client-side validation cannot prevent an evil hacker from submitting unexpected form data to your web server. You should always enforce your validation rules on the server. The only way to ensure that a required field has a value is to verify that the required field has a value on the server. The HTML5 required attribute does not guarantee anything. Summary The goal of this blog post was to describe the support for validation contained in the HTML5 standard. You learned how to use both the required and the pattern attributes in an HTML5 form. We also discussed how you can implement custom validation by taking advantage of the setCustomValidity() method. Finally, I discussed the available jQuery plugins for adding support for the HTM5 validation attributes to older browsers. Unfortunately, I am unaware of any jQuery plugin which provides a perfect solution to the problem of backwards compatibility.

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  • Heaps of Trouble?

    - by Paul White NZ
    If you’re not already a regular reader of Brad Schulz’s blog, you’re missing out on some great material.  In his latest entry, he is tasked with optimizing a query run against tables that have no indexes at all.  The problem is, predictably, that performance is not very good.  The catch is that we are not allowed to create any indexes (or even new statistics) as part of our optimization efforts. In this post, I’m going to look at the problem from a slightly different angle, and present an alternative solution to the one Brad found.  Inevitably, there’s going to be some overlap between our entries, and while you don’t necessarily need to read Brad’s post before this one, I do strongly recommend that you read it at some stage; he covers some important points that I won’t cover again here. The Example We’ll use data from the AdventureWorks database, copied to temporary unindexed tables.  A script to create these structures is shown below: CREATE TABLE #Custs ( CustomerID INTEGER NOT NULL, TerritoryID INTEGER NULL, CustomerType NCHAR(1) COLLATE SQL_Latin1_General_CP1_CI_AI NOT NULL, ); GO CREATE TABLE #Prods ( ProductMainID INTEGER NOT NULL, ProductSubID INTEGER NOT NULL, ProductSubSubID INTEGER NOT NULL, Name NVARCHAR(50) COLLATE SQL_Latin1_General_CP1_CI_AI NOT NULL, ); GO CREATE TABLE #OrdHeader ( SalesOrderID INTEGER NOT NULL, OrderDate DATETIME NOT NULL, SalesOrderNumber NVARCHAR(25) COLLATE SQL_Latin1_General_CP1_CI_AI NOT NULL, CustomerID INTEGER NOT NULL, ); GO CREATE TABLE #OrdDetail ( SalesOrderID INTEGER NOT NULL, OrderQty SMALLINT NOT NULL, LineTotal NUMERIC(38,6) NOT NULL, ProductMainID INTEGER NOT NULL, ProductSubID INTEGER NOT NULL, ProductSubSubID INTEGER NOT NULL, ); GO INSERT #Custs ( CustomerID, TerritoryID, CustomerType ) SELECT C.CustomerID, C.TerritoryID, C.CustomerType FROM AdventureWorks.Sales.Customer C WITH (TABLOCK); GO INSERT #Prods ( ProductMainID, ProductSubID, ProductSubSubID, Name ) SELECT P.ProductID, P.ProductID, P.ProductID, P.Name FROM AdventureWorks.Production.Product P WITH (TABLOCK); GO INSERT #OrdHeader ( SalesOrderID, OrderDate, SalesOrderNumber, CustomerID ) SELECT H.SalesOrderID, H.OrderDate, H.SalesOrderNumber, H.CustomerID FROM AdventureWorks.Sales.SalesOrderHeader H WITH (TABLOCK); GO INSERT #OrdDetail ( SalesOrderID, OrderQty, LineTotal, ProductMainID, ProductSubID, ProductSubSubID ) SELECT D.SalesOrderID, D.OrderQty, D.LineTotal, D.ProductID, D.ProductID, D.ProductID FROM AdventureWorks.Sales.SalesOrderDetail D WITH (TABLOCK); The query itself is a simple join of the four tables: SELECT P.ProductMainID AS PID, P.Name, D.OrderQty, H.SalesOrderNumber, H.OrderDate, C.TerritoryID FROM #Prods P JOIN #OrdDetail D ON P.ProductMainID = D.ProductMainID AND P.ProductSubID = D.ProductSubID AND P.ProductSubSubID = D.ProductSubSubID JOIN #OrdHeader H ON D.SalesOrderID = H.SalesOrderID JOIN #Custs C ON H.CustomerID = C.CustomerID ORDER BY P.ProductMainID ASC OPTION (RECOMPILE, MAXDOP 1); Remember that these tables have no indexes at all, and only the single-column sampled statistics SQL Server automatically creates (assuming default settings).  The estimated query plan produced for the test query looks like this (click to enlarge): The Problem The problem here is one of cardinality estimation – the number of rows SQL Server expects to find at each step of the plan.  The lack of indexes and useful statistical information means that SQL Server does not have the information it needs to make a good estimate.  Every join in the plan shown above estimates that it will produce just a single row as output.  Brad covers the factors that lead to the low estimates in his post. In reality, the join between the #Prods and #OrdDetail tables will produce 121,317 rows.  It should not surprise you that this has rather dire consequences for the remainder of the query plan.  In particular, it makes a nonsense of the optimizer’s decision to use Nested Loops to join to the two remaining tables.  Instead of scanning the #OrdHeader and #Custs tables once (as it expected), it has to perform 121,317 full scans of each.  The query takes somewhere in the region of twenty minutes to run to completion on my development machine. A Solution At this point, you may be thinking the same thing I was: if we really are stuck with no indexes, the best we can do is to use hash joins everywhere. We can force the exclusive use of hash joins in several ways, the two most common being join and query hints.  A join hint means writing the query using the INNER HASH JOIN syntax; using a query hint involves adding OPTION (HASH JOIN) at the bottom of the query.  The difference is that using join hints also forces the order of the join, whereas the query hint gives the optimizer freedom to reorder the joins at its discretion. Adding the OPTION (HASH JOIN) hint results in this estimated plan: That produces the correct output in around seven seconds, which is quite an improvement!  As a purely practical matter, and given the rigid rules of the environment we find ourselves in, we might leave things there.  (We can improve the hashing solution a bit – I’ll come back to that later on). Faster Nested Loops It might surprise you to hear that we can beat the performance of the hash join solution shown above using nested loops joins exclusively, and without breaking the rules we have been set. The key to this part is to realize that a condition like (A = B) can be expressed as (A <= B) AND (A >= B).  Armed with this tremendous new insight, we can rewrite the join predicates like so: SELECT P.ProductMainID AS PID, P.Name, D.OrderQty, H.SalesOrderNumber, H.OrderDate, C.TerritoryID FROM #OrdDetail D JOIN #OrdHeader H ON D.SalesOrderID >= H.SalesOrderID AND D.SalesOrderID <= H.SalesOrderID JOIN #Custs C ON H.CustomerID >= C.CustomerID AND H.CustomerID <= C.CustomerID JOIN #Prods P ON P.ProductMainID >= D.ProductMainID AND P.ProductMainID <= D.ProductMainID AND P.ProductSubID = D.ProductSubID AND P.ProductSubSubID = D.ProductSubSubID ORDER BY D.ProductMainID OPTION (RECOMPILE, LOOP JOIN, MAXDOP 1, FORCE ORDER); I’ve also added LOOP JOIN and FORCE ORDER query hints to ensure that only nested loops joins are used, and that the tables are joined in the order they appear.  The new estimated execution plan is: This new query runs in under 2 seconds. Why Is It Faster? The main reason for the improvement is the appearance of the eager Index Spools, which are also known as index-on-the-fly spools.  If you read my Inside The Optimiser series you might be interested to know that the rule responsible is called JoinToIndexOnTheFly. An eager index spool consumes all rows from the table it sits above, and builds a index suitable for the join to seek on.  Taking the index spool above the #Custs table as an example, it reads all the CustomerID and TerritoryID values with a single scan of the table, and builds an index keyed on CustomerID.  The term ‘eager’ means that the spool consumes all of its input rows when it starts up.  The index is built in a work table in tempdb, has no associated statistics, and only exists until the query finishes executing. The result is that each unindexed table is only scanned once, and just for the columns necessary to build the temporary index.  From that point on, every execution of the inner side of the join is answered by a seek on the temporary index – not the base table. A second optimization is that the sort on ProductMainID (required by the ORDER BY clause) is performed early, on just the rows coming from the #OrdDetail table.  The optimizer has a good estimate for the number of rows it needs to sort at that stage – it is just the cardinality of the table itself.  The accuracy of the estimate there is important because it helps determine the memory grant given to the sort operation.  Nested loops join preserves the order of rows on its outer input, so sorting early is safe.  (Hash joins do not preserve order in this way, of course). The extra lazy spool on the #Prods branch is a further optimization that avoids executing the seek on the temporary index if the value being joined (the ‘outer reference’) hasn’t changed from the last row received on the outer input.  It takes advantage of the fact that rows are still sorted on ProductMainID, so if duplicates exist, they will arrive at the join operator one after the other. The optimizer is quite conservative about introducing index spools into a plan, because creating and dropping a temporary index is a relatively expensive operation.  It’s presence in a plan is often an indication that a useful index is missing. I want to stress that I rewrote the query in this way primarily as an educational exercise – I can’t imagine having to do something so horrible to a production system. Improving the Hash Join I promised I would return to the solution that uses hash joins.  You might be puzzled that SQL Server can create three new indexes (and perform all those nested loops iterations) faster than it can perform three hash joins.  The answer, again, is down to the poor information available to the optimizer.  Let’s look at the hash join plan again: Two of the hash joins have single-row estimates on their build inputs.  SQL Server fixes the amount of memory available for the hash table based on this cardinality estimate, so at run time the hash join very quickly runs out of memory. This results in the join spilling hash buckets to disk, and any rows from the probe input that hash to the spilled buckets also get written to disk.  The join process then continues, and may again run out of memory.  This is a recursive process, which may eventually result in SQL Server resorting to a bailout join algorithm, which is guaranteed to complete eventually, but may be very slow.  The data sizes in the example tables are not large enough to force a hash bailout, but it does result in multiple levels of hash recursion.  You can see this for yourself by tracing the Hash Warning event using the Profiler tool. The final sort in the plan also suffers from a similar problem: it receives very little memory and has to perform multiple sort passes, saving intermediate runs to disk (the Sort Warnings Profiler event can be used to confirm this).  Notice also that because hash joins don’t preserve sort order, the sort cannot be pushed down the plan toward the #OrdDetail table, as in the nested loops plan. Ok, so now we understand the problems, what can we do to fix it?  We can address the hash spilling by forcing a different order for the joins: SELECT P.ProductMainID AS PID, P.Name, D.OrderQty, H.SalesOrderNumber, H.OrderDate, C.TerritoryID FROM #Prods P JOIN #Custs C JOIN #OrdHeader H ON H.CustomerID = C.CustomerID JOIN #OrdDetail D ON D.SalesOrderID = H.SalesOrderID ON P.ProductMainID = D.ProductMainID AND P.ProductSubID = D.ProductSubID AND P.ProductSubSubID = D.ProductSubSubID ORDER BY D.ProductMainID OPTION (MAXDOP 1, HASH JOIN, FORCE ORDER); With this plan, each of the inputs to the hash joins has a good estimate, and no hash recursion occurs.  The final sort still suffers from the one-row estimate problem, and we get a single-pass sort warning as it writes rows to disk.  Even so, the query runs to completion in three or four seconds.  That’s around half the time of the previous hashing solution, but still not as fast as the nested loops trickery. Final Thoughts SQL Server’s optimizer makes cost-based decisions, so it is vital to provide it with accurate information.  We can’t really blame the performance problems highlighted here on anything other than the decision to use completely unindexed tables, and not to allow the creation of additional statistics. I should probably stress that the nested loops solution shown above is not one I would normally contemplate in the real world.  It’s there primarily for its educational and entertainment value.  I might perhaps use it to demonstrate to the sceptical that SQL Server itself is crying out for an index. Be sure to read Brad’s original post for more details.  My grateful thanks to him for granting permission to reuse some of his material. Paul White Email: [email protected] Twitter: @PaulWhiteNZ

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  • Recreating OMS instances in a HA environment when instances on all nodes are lost

    - by rnigam
    Oracle highly recommends deploying EM in a HA environment. The best practices for HA deployments, backup and housekeeping of your Enterprise Manager environment are documented in the Oracle Enterprise Manager Advanced Configuration Guide. It is imperative that there is a good disaster recovery plan in place for your EM deployment. In this post I want to talk about a customer who failed to do the correct planning and housekeeping for EM and landed in a situation where we the all the OMSes were nearly blown away had we not jumped to help. We recently hit an issue at a customer site where we had a two node OMS setup of the Enterprise Manager and a RAC Database being used as the EM repository. An accidental delete of the OMS oracle home left us with a single node deployment. While we were trying to figure out a possible path to recover the first node, the second node was rebooted under a maintenance window. What followed was a complete site outage as the Admin and managed servers would not start on either of the nodes. In my situation there were - No backups of the Oracle Homes from any node - No OMS Configuration snapshots (created using the “emctl exportconfig oms” command) and the instance home was completely lost on node 1 which also had the Admin Server  We did however have: - A copy of the emkey.ora that I found under the OMS_ORACLE_HOME/ of the second node (NOTE: it is a bad practice to have your emkey present under the OMS Oracle home directory on the same server as the OMS. The backup of the emkey should be maintained on some other server. In this case however it was a savior in my situation since there were no backups - The oms oracle home on the second node but missing a number of files and had a number of changes done to the files in the home. There were a number of attempts to start the server by modifying various files based on the Weblogic server logs to have atleast node up and running but all of them failed. Here is how you can recover from this scenario: Follow these steps: STEP 1: Check status of emkey.ora Check whether the emkey exists is present in the EM repository or not. Run the following command: $OMS_ORACLE_HOME/bin/emctl status emkey If the output is something like this below then you are good to go and the key is present in the repository ./emctl status emkey Oracle Enterprise Manager 11g Release 1 Grid Control Copyright (c) 1996, 2010 Oracle Corporation. All rights reserved. Enter Enterprise Manager Root (SYSMAN) Password : The EMKey is configured properly. Here are the messages that you might see as the emctl status emkey output depending upon whether the EM Admin Server is up and if the key is configured properly: Case1:  AdminServer is up, emkey is proper in CredStore & not in repos. This is same as the output of the command shown above:The EMKey is configured properly Case 2: AdminServer is up, emkey is proper in CredStore & exists in repos:The EMKey is configured properly, but is not secure. Secure the EMKey by running "emctl config emkey -remove_from_repos".Case 3: AdminServer is down or emkey is corrupted in CredStore) & (emkey exists in repos): The EMKey exists in the Management Repository, but is not configured properly or is corrupted in the credential store.Configure the EMKey by running "emctl config emkey -copy_to_credstore".Case 4: (AdminServer is down or emkey is corrupted in CredStore) & (emkey does not exist in repos): The EMKey is not configured properly or is corrupted in the credential store and does not exist in the Management Repository. To correct the problem:1) Get the backed up emkey.ora file.2) Configure the emkey by running "emctl config emkey -copy_to_credstore_from_file". If not the key was not secured properly, we will have to be put in the repository before proceeding. Look at the next step 2 for doing this There may be cases (like mine) where running emctl may give errors like the following: $OMS_ORACLE_HOME/bin/emctl status emkey Exception in thread “Main Thread” java.lang.NoClassDefFoundError: oracle/security/pki/OracleWallet At oracle.sysman.emctl.config.oms.EMKeyCmds.main (EMKeyCmds.java:658) Just move to the next step to put the key back in the repository STEP 2: Put emkey.ora back in the repository Skip this step if your emkey.ora is present in the repository. If not, you need to put the key back in the repository See if you can run the following command (with sample output): $OMS_ORACLE_HOME/bin/emctl config emkey –copy_to_repos Oracle Enterprise Manager 11g Release 1 Grid Control Copyright (c) 1996, 2010 Oracle Corporation. All rights reserved. The EMKey has been copied to the Management Repository. This operation will cause the EMKey to become unsecure. After the required operation has been completed, secure the EMKey by running "emctl config emkey -remove_from_repos". Typically the key is present under $OMS_ORACLE_HOME/sysman/config directory before being removed after the install as a best practice. If you hit any errors while running emctl commands like the one mentioned in step 1, jump to step 3 and we will take care of the emkey.ora in Step 5 STEP 3: Get the port information Check for the existing port information in the emd.properties file under EM_INSTANCE_DIRECTORY (typically gc_inst directory right above the Middleware home where you have deployed em. For eg. /u01/app/oracle/product/gc_inst in case your oms home is /u01/app/oracle/product/Middleware/oms11g) In my case I got the information from the emgc.properties present in the gc_inst on the second node. If you can run emctl you may want to try the following command as well $OMS_ORACLE_HOME/bin/emctl status oms –details Note this information as this will be used in the next step STEP 4: Perform cleanup on Node 1 Note the oracle home of the Weblogic and OMS, get the list of applied patches in the homes (using opatch lsinventory command), take a backup copy of the home just in case we need it and then de-install/remove oracle homes, update inventory and cleanup processes on the first node STEP 5: Perform Software Only Installation of OMS on Node 1 Perform Weblogic 10.3.2 installation exactly under the same location as present in the earlier installation. Perform software only installation of the OMS using the following command. This will not run any configuration assistants and bypass all user interface validations runInstaller –noconfig -validationaswarnings Select the “Additional OMS” option while performing the installation. Provide the same path for OMS and Instance directories like the previous installation Use the port information collected in Step 3 while performing the installation. Once the installation is complete run the allroot.sh script to complete the binary deployment STEP 6: Apply one-off patches At this point you can apply any patches to the OMS Oracle Home previously. You only need to run opatch to install the patch in the home and not required to run the SQLs STEP 7: Copy EM key This step is only required if you were not able to use emctl command to put the emkey back into the EM repository in STEP 2 Copy the emkey.ora file of the old installation you have under $OMS_ORACLE_HOME/sysman/config directory of the newly installed OMS STEP 8: Configure Grid Control Domain Run the following command to configure the EM domain and OMS. Note that you need to use a different GC Domain name than what you used earlier. For example I have used GCDOMAIN11 as the new domain name when my previous domain name was GCDOMAIN $OMS_ORACLE_HOME/bin/omsca new –AS_USERNAME weblogic –EM_DOMAIN_NAME GCDOMAIN11 –NM_USER nodemanager -nostart This command as shown below will prompt for a number of inputs like Admin Server hostname, port, password, etc. Verify if the defaults shown are correct by pressing enter or provide a new value STEP 9: Run Add-ON Configuration Assistant After this step run the following add-on configuration assistant. This was used in my case to configure the virtualization add-on $OMS_ORACLE_HOME/addonca -oui -omsonly -name vt -install gc STEP 10: Start the OMS Now start the OMS using $OMS_ORACLE_HOME/bin/emctl start oms In a multi-node setup like mine you would either have a software load balancer or DNS round robin (using a virtual host name that resolves to one of multiple OMS hostnames) being used for load balancing. Secure the OMS against the SLB or DNS virtual hostname using the following $ OMS_HOME/bin/emctl secure oms -host slb.example.com -secure_port 1159 -slb_port 1159 -slb_console_port 443 STEP 11: Configure the Agent From the $AGENT_ORACLE_HOME/bin run the ./agentca –f At this point you should have your OMS on node 1 fully re-covered. Clean up node 2 and use the normal Additional OMS installation process documented in the official installation guide to add the additional OMS on node 2 Summary It took us nearly a little over two days to completely recover the environment with some other non-EM related issues that hit us along the way as well. In the end a situation like this could have been completely avoided had the proper housekeeping and backup of the Enterprise Manager Deployment been done in the first place. This is going to a topic that we cover in the next post. In the meantime please do refer to the Oracle Enterprise Manager Advanced Configuration Guide for planning your EM installation, backup and housekeeping procedures. This can be found here: http://download.oracle.com/docs/cd/E11857_01/index.htm Thanks This post would not have been possible without Raj Aggarwal, Prasad Chebrolu and Ravikumar Basa who helped to recover the environment and provided all the support we needed

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  • Metro: Query Selectors

    - by Stephen.Walther
    The goal of this blog entry is to explain how to perform queries using selectors when using the WinJS library. In particular, you learn how to use the WinJS.Utilities.query() method and the QueryCollection class to retrieve and modify the elements of an HTML document. Introduction to Selectors When you are building a Web application, you need some way of easily retrieving elements from an HTML document. For example, you might want to retrieve all of the input elements which have a certain class. Or, you might want to retrieve the one and only element with an id of favoriteColor. The standard way of retrieving elements from an HTML document is by using a selector. Anyone who has ever created a Cascading Style Sheet has already used selectors. You use selectors in Cascading Style Sheets to apply formatting rules to elements in a document. For example, the following Cascading Style Sheet rule changes the background color of every INPUT element with a class of .required in a document to the color red: input.red { background-color: red } The “input.red” part is the selector which matches all INPUT elements with a class of red. The W3C standard for selectors (technically, their recommendation) is entitled “Selectors Level 3” and the standard is located here: http://www.w3.org/TR/css3-selectors/ Selectors are not only useful for adding formatting to the elements of a document. Selectors are also useful when you need to apply behavior to the elements of a document. For example, you might want to select a particular BUTTON element with a selector and add a click handler to the element so that something happens whenever you click the button. Selectors are not specific to Cascading Style Sheets. You can use selectors in your JavaScript code to retrieve elements from an HTML document. jQuery is famous for its support for selectors. Using jQuery, you can use a selector to retrieve matching elements from a document and modify the elements. The WinJS library enables you to perform the same types of queries as jQuery using the W3C selector syntax. Performing Queries with the WinJS.Utilities.query() Method When using the WinJS library, you perform a query using a selector by using the WinJS.Utilities.query() method.  The following HTML document contains a BUTTON and a DIV element: <!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>Application1</title> <!-- WinJS references --> <link href="//Microsoft.WinJS.0.6/css/ui-dark.css" rel="stylesheet"> <script src="//Microsoft.WinJS.0.6/js/base.js"></script> <script src="//Microsoft.WinJS.0.6/js/ui.js"></script> <!-- Application1 references --> <link href="/css/default.css" rel="stylesheet"> <script src="/js/default.js"></script> </head> <body> <button>Click Me!</button> <div style="display:none"> <h1>Secret Message</h1> </div> </body> </html> The document contains a reference to the following JavaScript file named \js\default.js: (function () { "use strict"; var app = WinJS.Application; app.onactivated = function (eventObject) { if (eventObject.detail.kind === Windows.ApplicationModel.Activation.ActivationKind.launch) { WinJS.Utilities.query("button").listen("click", function () { WinJS.Utilities.query("div").clearStyle("display"); }); } }; app.start(); })(); The default.js script uses the WinJS.Utilities.query() method to retrieve all of the BUTTON elements in the page. The listen() method is used to wire an event handler to the BUTTON click event. When you click the BUTTON, the secret message contained in the hidden DIV element is displayed. The clearStyle() method is used to remove the display:none style attribute from the DIV element. Under the covers, the WinJS.Utilities.query() method uses the standard querySelectorAll() method. This means that you can use any selector which is compatible with the querySelectorAll() method when using the WinJS.Utilities.query() method. The querySelectorAll() method is defined in the W3C Selectors API Level 1 standard located here: http://www.w3.org/TR/selectors-api/ Unlike the querySelectorAll() method, the WinJS.Utilities.query() method returns a QueryCollection. We talk about the methods of the QueryCollection class below. Retrieving a Single Element with the WinJS.Utilities.id() Method If you want to retrieve a single element from a document, instead of matching a set of elements, then you can use the WinJS.Utilities.id() method. For example, the following line of code changes the background color of an element to the color red: WinJS.Utilities.id("message").setStyle("background-color", "red"); The statement above matches the one and only element with an Id of message. For example, the statement matches the following DIV element: <div id="message">Hello!</div> Notice that you do not use a hash when matching a single element with the WinJS.Utilities.id() method. You would need to use a hash when using the WinJS.Utilities.query() method to do the same thing like this: WinJS.Utilities.query("#message").setStyle("background-color", "red"); Under the covers, the WinJS.Utilities.id() method calls the standard document.getElementById() method. The WinJS.Utilities.id() method returns the result as a QueryCollection. If no element matches the identifier passed to WinJS.Utilities.id() then you do not get an error. Instead, you get a QueryCollection with no elements (length=0). Using the WinJS.Utilities.children() method The WinJS.Utilities.children() method enables you to retrieve a QueryCollection which contains all of the children of a DOM element. For example, imagine that you have a DIV element which contains children DIV elements like this: <div id="discussContainer"> <div>Message 1</div> <div>Message 2</div> <div>Message 3</div> </div> You can use the following code to add borders around all of the child DIV element and not the container DIV element: var discussContainer = WinJS.Utilities.id("discussContainer").get(0); WinJS.Utilities.children(discussContainer).setStyle("border", "2px dashed red");   It is important to understand that the WinJS.Utilities.children() method only works with a DOM element and not a QueryCollection. Notice that the get() method is used to retrieve the DOM element which represents the discussContainer. Working with the QueryCollection Class Both the WinJS.Utilities.query() method and the WinJS.Utilities.id() method return an instance of the QueryCollection class. The QueryCollection class derives from the base JavaScript Array class and adds several useful methods for working with HTML elements: addClass(name) – Adds a class to every element in the QueryCollection. clearStyle(name) – Removes a style from every element in the QueryCollection. conrols(ctor, options) – Enables you to create controls. get(index) – Retrieves the element from the QueryCollection at the specified index. getAttribute(name) – Retrieves the value of an attribute for the first element in the QueryCollection. hasClass(name) – Returns true if the first element in the QueryCollection has a certain class. include(items) – Includes a collection of items in the QueryCollection. listen(eventType, listener, capture) – Adds an event listener to every element in the QueryCollection. query(query) – Performs an additional query on the QueryCollection and returns a new QueryCollection. removeClass(name) – Removes a class from the every element in the QueryCollection. removeEventListener(eventType, listener, capture) – Removes an event listener from every element in the QueryCollection. setAttribute(name, value) – Adds an attribute to every element in the QueryCollection. setStyle(name, value) – Adds a style attribute to every element in the QueryCollection. template(templateElement, data, renderDonePromiseContract) – Renders a template using the supplied data.  toggleClass(name) – Toggles the specified class for every element in the QueryCollection. Because the QueryCollection class derives from the base Array class, it also contains all of the standard Array methods like forEach() and slice(). Summary In this blog post, I’ve described how you can perform queries using selectors within a Windows Metro Style application written with JavaScript. You learned how to return an instance of the QueryCollection class by using the WinJS.Utilities.query(), WinJS.Utilities.id(), and WinJS.Utilities.children() methods. You also learned about the methods of the QueryCollection class.

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  • Is recursion really bad?

    - by dotneteer
    After my previous post about the stack space, it appears that there is perception from the feedback that recursion is bad and we should avoid deep recursion. After writing a compiler, I know that the modern computer and compiler are complex enough and one cannot automatically assume that a hand crafted code would out-perform the compiler optimization. The only way is to do some prototype to find out. So why recursive code may not perform as well? Compilers place frames on a stack. In additional to arguments and local variables, compiles also need to place frame and program pointers on the frame, resulting in overheads. So why hand-crafted code may not performance as well? The stack used by a compiler is a simpler data structure and can grow and shrink cleanly. To replace recursion with out own stack, our stack is allocated in the heap that is far more complicated to manage. There could be overhead as well if the compiler needs to mark objects for garbage collection. Compiler also needs to worry about the memory fragmentation. Then there is additional complexity: CPUs have registers and multiple levels of cache. Register access is a few times faster than in-CPU cache access and is a few 10s times than on-board memory access. So it is up to the OS and compiler to maximize the use of register and in-CPU cache. For my particular problem, I did an experiment to rewrite my c# version of recursive code with a loop and stack approach. So here are the outcomes of the two approaches:   Recursive call Loop and Stack Lines of code for the algorithm 17 46 Speed Baseline 3% faster Readability Clean Far more complex So at the end, I was able to achieve 3% better performance with other drawbacks. My message is never assuming your sophisticated approach would automatically work out better than a simpler approach with a modern computer and compiler. Gage carefully before committing to a more complex approach.

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  • Metro: Promises

    - by Stephen.Walther
    The goal of this blog entry is to describe the Promise class in the WinJS library. You can use promises whenever you need to perform an asynchronous operation such as retrieving data from a remote website or a file from the file system. Promises are used extensively in the WinJS library. Asynchronous Programming Some code executes immediately, some code requires time to complete or might never complete at all. For example, retrieving the value of a local variable is an immediate operation. Retrieving data from a remote website takes longer or might not complete at all. When an operation might take a long time to complete, you should write your code so that it executes asynchronously. Instead of waiting for an operation to complete, you should start the operation and then do something else until you receive a signal that the operation is complete. An analogy. Some telephone customer service lines require you to wait on hold – listening to really bad music – until a customer service representative is available. This is synchronous programming and very wasteful of your time. Some newer customer service lines enable you to enter your telephone number so the customer service representative can call you back when a customer representative becomes available. This approach is much less wasteful of your time because you can do useful things while waiting for the callback. There are several patterns that you can use to write code which executes asynchronously. The most popular pattern in JavaScript is the callback pattern. When you call a function which might take a long time to return a result, you pass a callback function to the function. For example, the following code (which uses jQuery) includes a function named getFlickrPhotos which returns photos from the Flickr website which match a set of tags (such as “dog” and “funny”): function getFlickrPhotos(tags, callback) { $.getJSON( "http://api.flickr.com/services/feeds/photos_public.gne?jsoncallback=?", { tags: tags, tagmode: "all", format: "json" }, function (data) { if (callback) { callback(data.items); } } ); } getFlickrPhotos("funny, dogs", function(data) { $.each(data, function(index, item) { console.log(item); }); }); The getFlickr() function includes a callback parameter. When you call the getFlickr() function, you pass a function to the callback parameter which gets executed when the getFlicker() function finishes retrieving the list of photos from the Flickr web service. In the code above, the callback function simply iterates through the results and writes each result to the console. Using callbacks is a natural way to perform asynchronous programming with JavaScript. Instead of waiting for an operation to complete, sitting there and listening to really bad music, you can get a callback when the operation is complete. Using Promises The CommonJS website defines a promise like this (http://wiki.commonjs.org/wiki/Promises): “Promises provide a well-defined interface for interacting with an object that represents the result of an action that is performed asynchronously, and may or may not be finished at any given point in time. By utilizing a standard interface, different components can return promises for asynchronous actions and consumers can utilize the promises in a predictable manner.” A promise provides a standard pattern for specifying callbacks. In the WinJS library, when you create a promise, you can specify three callbacks: a complete callback, a failure callback, and a progress callback. Promises are used extensively in the WinJS library. The methods in the animation library, the control library, and the binding library all use promises. For example, the xhr() method included in the WinJS base library returns a promise. The xhr() method wraps calls to the standard XmlHttpRequest object in a promise. The following code illustrates how you can use the xhr() method to perform an Ajax request which retrieves a file named Photos.txt: var options = { url: "/data/photos.txt" }; WinJS.xhr(options).then( function (xmlHttpRequest) { console.log("success"); var data = JSON.parse(xmlHttpRequest.responseText); console.log(data); }, function(xmlHttpRequest) { console.log("fail"); }, function(xmlHttpRequest) { console.log("progress"); } ) The WinJS.xhr() method returns a promise. The Promise class includes a then() method which accepts three callback functions: a complete callback, an error callback, and a progress callback: Promise.then(completeCallback, errorCallback, progressCallback) In the code above, three anonymous functions are passed to the then() method. The three callbacks simply write a message to the JavaScript Console. The complete callback also dumps all of the data retrieved from the photos.txt file. Creating Promises You can create your own promises by creating a new instance of the Promise class. The constructor for the Promise class requires a function which accepts three parameters: a complete, error, and progress function parameter. For example, the code below illustrates how you can create a method named wait10Seconds() which returns a promise. The progress function is called every second and the complete function is not called until 10 seconds have passed: (function () { "use strict"; var app = WinJS.Application; function wait10Seconds() { return new WinJS.Promise(function (complete, error, progress) { var seconds = 0; var intervalId = window.setInterval(function () { seconds++; progress(seconds); if (seconds > 9) { window.clearInterval(intervalId); complete(); } }, 1000); }); } app.onactivated = function (eventObject) { if (eventObject.detail.kind === Windows.ApplicationModel.Activation.ActivationKind.launch) { wait10Seconds().then( function () { console.log("complete") }, function () { console.log("error") }, function (seconds) { console.log("progress:" + seconds) } ); } } app.start(); })(); All of the work happens in the constructor function for the promise. The window.setInterval() method is used to execute code every second. Every second, the progress() callback method is called. If more than 10 seconds have passed then the complete() callback method is called and the clearInterval() method is called. When you execute the code above, you can see the output in the Visual Studio JavaScript Console. Creating a Timeout Promise In the previous section, we created a custom Promise which uses the window.setInterval() method to complete the promise after 10 seconds. We really did not need to create a custom promise because the Promise class already includes a static method for returning promises which complete after a certain interval. The code below illustrates how you can use the timeout() method. The timeout() method returns a promise which completes after a certain number of milliseconds. WinJS.Promise.timeout(3000).then( function(){console.log("complete")}, function(){console.log("error")}, function(){console.log("progress")} ); In the code above, the Promise completes after 3 seconds (3000 milliseconds). The Promise returned by the timeout() method does not support progress events. Therefore, the only message written to the console is the message “complete” after 10 seconds. Canceling Promises Some promises, but not all, support cancellation. When you cancel a promise, the promise’s error callback is executed. For example, the following code uses the WinJS.xhr() method to perform an Ajax request. However, immediately after the Ajax request is made, the request is cancelled. // Specify Ajax request options var options = { url: "/data/photos.txt" }; // Make the Ajax request var request = WinJS.xhr(options).then( function (xmlHttpRequest) { console.log("success"); }, function (xmlHttpRequest) { console.log("fail"); }, function (xmlHttpRequest) { console.log("progress"); } ); // Cancel the Ajax request request.cancel(); When you run the code above, the message “fail” is written to the Visual Studio JavaScript Console. Composing Promises You can build promises out of other promises. In other words, you can compose promises. There are two static methods of the Promise class which you can use to compose promises: the join() method and the any() method. When you join promises, a promise is complete when all of the joined promises are complete. When you use the any() method, a promise is complete when any of the promises complete. The following code illustrates how to use the join() method. A new promise is created out of two timeout promises. The new promise does not complete until both of the timeout promises complete: WinJS.Promise.join([WinJS.Promise.timeout(1000), WinJS.Promise.timeout(5000)]) .then(function () { console.log("complete"); }); The message “complete” will not be written to the JavaScript Console until both promises passed to the join() method completes. The message won’t be written for 5 seconds (5,000 milliseconds). The any() method completes when any promise passed to the any() method completes: WinJS.Promise.any([WinJS.Promise.timeout(1000), WinJS.Promise.timeout(5000)]) .then(function () { console.log("complete"); }); The code above writes the message “complete” to the JavaScript Console after 1 second (1,000 milliseconds). The message is written to the JavaScript console immediately after the first promise completes and before the second promise completes. Summary The goal of this blog entry was to describe WinJS promises. First, we discussed how promises enable you to easily write code which performs asynchronous actions. You learned how to use a promise when performing an Ajax request. Next, we discussed how you can create your own promises. You learned how to create a new promise by creating a constructor function with complete, error, and progress parameters. Finally, you learned about several advanced methods of promises. You learned how to use the timeout() method to create promises which complete after an interval of time. You also learned how to cancel promises and compose promises from other promises.

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