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• Five Best Practices for Going Mobile

  - by kellsey.ruppel

  76% of IT decision makers indicate mobile trends will have a high to extremely high impact on their organization. Has your organization gone mobile? Looking for some ideas on how to get started? John Brunswick shares his Best Practices for Going Mobile. Mobile technology has gone from nice-to-have to a cornerstone of user engagement. Mobile access enables social networking, decision support, purchasing, content consumption, and location-based searching, extending experiences beyond what is available in traditional desktop computing.  Organizations rushing to ensure their brand's mobile availability may have taken a tactical approach to implementation, but strategically approaching mobile can enable greater returns on a similar investment and subsequent mobile projects. Here are some strategic considerations for delivering products, services, and information to mobile constituents.  Who, Why, and What? Ask yourself these key questions: who are you attempting to engage through the channel, and why are they engaging you through this channel? What experience will satisfy their needs? What outcome will support your core business? Will you be informing and/or transacting with this person?  Mobile Behavior. Mobile users generally engage for a very specific purpose. Ensure that access to information, services, and products is streamlined. Arriving on a mobile site through search only to be asked to search again frustrates users.  Mobile Is Broad. After establishing the audience and goal, review technology requirements to support them. Do you need a mobile Website, native mobile application, or both? Do you need to support multiple devices? Know the difference between native mobile and mobile Web.  Social Strategy. Users are more likely to trust reviews from peers than marketing information from a vendor. If you are selling products or services, be sure to make social integration part of your strategy.  Content Management. Consider a shared content platform strategy for Web and mobile projects. Fresh, consistent content is important for high-quality experiences. Read more from John Brunswick.We'll also be talking mobile strategies and how you can transform your portal experience and optimize online engagement -- making your portals more interactive and more engaging across multiple channels in a webcast tomorrow. We hope you'll join us!

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• Error installing RVM

  - by Dbugger

  I am following this guide, but this is the output I receive. What am the problem? dbugger@mercury:~$ \curl -sSL https://get.rvm.io | bash -s stable --rails Downloading https://github.com/wayneeseguin/rvm/archive/stable.tar.gz Upgrading the RVM installation in /home/dbugger/.rvm/ RVM PATH line found in /home/dbugger/.profile /home/dbugger/.bashrc /home/dbugger/.zshrc. RVM sourcing line found in /home/dbugger/.bash_profile /home/dbugger/.zlogin. Upgrade of RVM in /home/dbugger/.rvm/ is complete. # Enrique, # # Thank you for using RVM! # We sincerely hope that RVM helps to make your life easier and more enjoyable!!! # # ~Wayne, Michal & team. In case of problems: http://rvm.io/help and https://twitter.com/rvm_io Upgrade Notes: * No new notes to display. rvm 1.25.27 (stable) by Wayne E. Seguin <[email protected]>, Michal Papis <[email protected]> [https://rvm.io/] Searching for binary rubies, this might take some time. No binary rubies available for: ubuntu/14.04/x86_64/ruby-2.1.2. Continuing with compilation. Please read 'rvm help mount' to get more information on binary rubies. Checking requirements for ubuntu. Installing requirements for ubuntu. Updating system.......... Installing required packages: gawk, libreadline6-dev, libssl-dev, libyaml-dev, libsqlite3-dev, sqlite3.... Error running 'requirements_debian_libs_install gawk libreadline6-dev libssl-dev libyaml-dev libsqlite3-dev sqlite3', showing last 15 lines of /home/dbugger/.rvm/log/1401804140_ruby-2.1.2/package_install_gawk_libreadline6-dev_libssl-dev_libyaml-dev_libsqlite3-dev_sqlite3.log ++ /scripts/functions/utility : __rvm_try_sudo() 405 > sudo -p '%p password required for '\''apt-get --no-install-recommends --yes install gawk libreadline6-dev libssl-dev libyaml-dev libsqlite3-dev sqlite3'\'': ' apt-get --no-install-recommends --yes install gawk libreadline6-dev libssl-dev libyaml-dev libsqlite3-dev sqlite3 Reading package lists... Building dependency tree... Reading state information... Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation: The following packages have unmet dependencies: libssl-dev : Depends: libssl1.0.0 (= 1.0.1f-1ubuntu2) but 1.0.1f-1ubuntu2.1 is to be installed E: Unable to correct problems, you have held broken packages. ++ /scripts/functions/utility : __rvm_try_sudo() 405 > return 100 ++ /scripts/functions/requirements/ubuntu : requirements_debian_libs_install() 36 > return 100 Requirements installation failed with status: 100.

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• OWB 11gR2 &ndash; OMB and File Editing

  - by David Allan

  Here we will see how we can use the IDE for editing OMB scripts. The 11gR2 release is based on the common Oracle platform IDE used also by JDeveloper. It comes with a bunch of standard behavior for editing and rendering code. One of the lesser known things is that if you drop a text file into OWB you can edit it. So you can drop your tcl scripts right into OWB and edit in-place, and don’t need another IDE like Eclipse just for this task. Cool, so you have the file here. There may be no line numbers, you can toggle line numbers on by right clicking in the gutter. If we edit the file within the OWB IDE, the save is a little different from normal. OWB doesn’t normally manipulate files so things like ctrl-s to save, saves the OWB objects, but if you edit a file the closing of the file will ask if you want to save it – check it out. Now we enter the realm of ‘he who dares’…. Note the IDE doesn’t know about tcl files out of the box, so you see above there is no syntax highlighting. The code is identified by the extension… .java is java, .html is HTML etc. With OWB, the OMB scripts are tcl, we usually have .tcl extension on these files. One of the things we can do to trick up the syntax highlighting is to simply rename the file to have a .java suffix, then all of a sudden we get syntax highlighting, see the illustration here where side by side we see a the file with a .java extension and a .tcl extension. Not ideal pretending to be .java but gets us a way to having something more useful than notepad. We can then change the syntax highlighting such that we get Eclipse like highlighting within the IDE from the Tools Preferences option; You then get the Eclipse like rendering albeit using a little tweak on the file names… Might be useful if you are doing any kind of heavy duty OMB script development and just want a single IDE. The OMBPlus panel is then at hand for executing and testing it out.

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• Web Apps vs Web Services: 302s and 401s are not always good Friends

  - by Your DisplayName here!

  It is not very uncommon to have web sites that have web UX and services content. The UX part maybe uses WS-Federation (or some other redirect based mechanism). That means whenever an authorization error occurs (401 status code), this is picked by the corresponding redirect module and turned into a redirect (302) to the login page. All is good. But in services, when you emit a 401, you typically want that status code to travel back to the client agent, so it can do error handling. These two approaches conflict. If you think (like me) that you should separate UX and services into separate apps, you don’t need to read on. Just do it ;) If you need to mix both mechanisms in a single app – here’s how I solved it for a project. I sub classed the redirect module – this was in my case the WIF WS-Federation HTTP module and modified the OnAuthorizationFailed method. In there I check for a special HttpContext item, and if that is present, I suppress the redirect. Otherwise everything works as normal: class ServiceAwareWSFederationAuthenticationModule : WSFederationAuthenticationModule {     protected override void OnAuthorizationFailed(AuthorizationFailedEventArgs e)     {         base.OnAuthorizationFailed(e);         var isService = HttpContext.Current.Items[AdvertiseWcfInHttpPipelineBehavior.DefaultLabel];         if (isService != null)         {             e.RedirectToIdentityProvider = false;         }     } } Now the question is, how do you smuggle that value into the HttpContext. If it is a MVC based web service, that’s easy of course. In the case of WCF, one approach that worked for me was to set it in a service behavior (dispatch message inspector to be exact): public void BeforeSendReply( ref Message reply, object correlationState) {     if (HttpContext.Current != null)     {         HttpContext.Current.Items[DefaultLabel] = true;     } } HTH

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• Partial Submit vs. Auto Submit

  - by Frank Nimphius

  Partial Submit ADF Faces adds the concept of partial form submit to JavaServer Faces 1.2 and beyond. A partial submit actually is a form submit that does not require a page refresh and only updates components in the view that are referenced from the command component PartialTriggers property. Another option for refreshing a component in response to a partial submit is call AdfContext.getCurrentInstance.addPartialTarget(component_instance_handle_goes_here)in a managed bean. If a form contains required fields that the user left empty invoking the partial submit, then errors are shown for each of the field as the full form gets submitted. Autosubmit An input component that has its autosubmit property set to true also performs a partial submit of the form. However, this time it doesn't submit the entire form but only the component that triggers the submit plus components referenced it in their PartialTriggers property. For example, consider a form that has three input fields inpA, inpB and inpC with autosubmit=true set on inpA and required=true set on inpB and inpC. use case 1: Running the view, entering data into inpA and then tabbing out of the field will submit the content for inpA but not for inpB and inpC. Further more, none of the required field settings on inpB and inpC causes an error. use case 2: You change the configuration of inpC and set its PartialTriggers property to point to the ID of component inpA. When rerunning the sample, entering a value into inpA and tabbing out of the field will now submit the inpA and inpC fields and thus show an error for the missing required value on inpC. Internally, using autosubmit=true on an input component sets the event root to just this field, which good to have in case of dependent field validation or behavior. The event root can extended to include other components by using the Partial Triggers property on these components to point to the input field that has autosubmit=true defined. PartialSubmit vs. AutoSubmit Partial submit set on a command component submits the whole form and leaves it to the developer to decide which UI component is refreshed in response. Client side required field validation (as well as the server side equivalent) is not disabled by executed in this scenario. Setting immediate=true on the command item to skip validation doesn't help as it would also skip the model update. Auto submit is a functionality on the input components and also performs a partial form submit. However, in addition an event root is defined that narrows the scope for the submitted data and thus the components that are validated on the request. To read more about this topic, see: http://docs.oracle.com/cd/E23943_01/web.1111/b31973/af_lifecycle.htm#CIAHCFJF

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• How can I keep directories in sync

  - by Guillaume Boudreau

  I have a directory, dirA, that users can work in: they can create, modify, rename and delete files & sub-directores in dirA. I want to keep another directory, dirB, in sync with dirA. What I'd like, is a discussion on finding a working algorithm that would achieve the above, with the limitations listed below. Requirements: 1. Something asynchronous - I don't want to stop file operations in dirA while I work in dirB. 2. I can't assume that I can just blindly rsync dirA to dirB on regular interval - dirA could contain millions of files & directories, and terrabytes of data. Completely walking the dirA tree could take hours. Those two requirements makes this really difficult. Having it asynchronous means that when I start working on a specific file from dirA, it might have moved a lot since it appeared. And the second limitation means that I really need to watch dirA, and work on atomic file operations that I notice. Current (broken) implementation: 1. Log all file & directory operations in dirA. 2. Using a separate process, read that log, and 'repeat' all the logged operations in dirB. Why is it broken: echo 1 > dirA/file1 # Allow the 'log reader' process to create dirB/file1: log = "write dirA/file1"; action = cp dirA/file1 dirB/file1; result = OK echo 1 > dirA/file2 mv dirA/file1 dirA/file3 mv dirA/file2 dirA/file1 rm dirA/file3 # End result: file1 contains '1' # 'log reader' process starts working on the 4 above file operations: log = "write file2"; action = cp dirA/file2 dirB/file2; result = failed: there is no dirA/file2 log = "rename file1 file3"; action = mv dirB/file1 dirB/file3; result = OK log = "rename file2 file1"; action = mv dirB/file2 dirB/file1; result = failed: there is no dirB/file2 log = "delete file3"; action = rm dirB/file3; result = OK # End result in dirB: no more files! Another broken example: echo 1 > dirA/dir1/file1 mv dirA/dir1 dirA/dir2 # 'log reader' process starts working on the 2 above file operations: log = "write file1"; action = cp dirA/dir1/file1 dirB/dir1/file1; result = failed: there is no dirA/dir1/file1 log = "rename dir1 dir2"; action = mv dirB/dir1 dirB/dir2; result = failed: there is no dirA/dir1 # End result if dirB: nothing!

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• Code Analysis Rule Sets in Visual Studio 2010

  - by Anthony Trudeau

  Microsoft Visual Studio 2010 introduces the concept of rule sets when configuring code analysis.  This is a valuable change from Visual Studio 2008 that I didn't even realize I wanted.  Visual Studio 2008 by default selected all rules and then you had to remove rules on an item by item basis. The rule sets fall into logical groups including "Microsoft All Rules", "Microsoft Basic Correctness Rules", "Microsoft Security Rules", et al.  And within the project properties you can select one rule set, multiple rule sets, or you can define your own rule set based upon another. Selecting a single rule set is obviously the easiest option.  The default rule set when you create a new project is the "Microsoft Minimum Recommended Rules".  However, in my opinion the recommended rules are just too permissive.  For that reason you might want to change your rule set to "Microsoft All Rules" until you get around to creating your own rule set; or alternately you can select multiple rule sets which is an option from the rule set combo box.  The Visual Studio documentation has comprehensive help on what is contained within the rule sets. Creating your own rule set is easy if not obvious.  You need to start a rule set from an existing rule set.  To get started select a rule set in the combo box within the Code Analysis tab of the project properties.  I selected the "Microsoft All Rules" for my rule set, but you may find it easier to start with the "Microsoft Minimum Recommended Rules" if your rules are on the more permissive side. Once your rule set is selected click the Open button.  This will display a dialog that is similar in composition to the rules selection from Visual Studio 2008.  Browsing through the tree view you can select or deselect individual rules within their categories; and you can indicate that the rules are flagged as errors instead of the default which is a warning.  A nice touch to the form is that you get a help pane when you select an individual rule.  That helped me considerably when I first configured my rule set. Once you have finished selecting your rules click the Save tool button, specify a location and name, and click the Save button on the Save As dialog.  Once you're back on the Code Analysis tab you'll choose the Browse option within the combo box and open the file you just created.

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• Less Can Be More In E-Commerce

  - by Michael Hylton

  Today’s consumers are inundated with product choices and vendors. Visit your favorite electronics retailer and see the vast assortment of flat panel televisions. Or the variety of detergents at the supermarket. All of this can be daunting for the average consumer who is looking for the products and services that interest them.  In a study titled “Choice is Demotivating: Can One Desire Too Much of a Good Thing”, the author, Sheena Iyengar found that participants actually reported greater subsequent satisfaction with their selections and wrote better essays when their original set of options had been limited. The same can be said for e-commerce and your website. Being able to quickly convert shoppers into buyers with effective merchandising is what makes leading businesses successful. You want to engage each individual visitor with the most-relevant content to drive higher conversions and order values while decreasing abandonment, but predicting what will resonate with each customer is difficult. In a world of choices, online merchandizing tools can help personalize, streamline, and refine what your customers view when they browse your online catalog. The key to being effective is to align your products and content as closely as possible with the customer’s needs. The goal on the home page is to promote your brand and push visitors farther into the site. The home page is often the starting point for repeat customers as well as for new visitors hoping to address their current product needs. As the customer selects different filters and narrows the choices, valuable information is being provided to the retailer about the customer’s current need—regardless of previous search behavior or what other customers with a similar demographic profile have purchased. Together with search pages, category browse pages are among the primary options available to customers as a means of finding products on your site. Once a customer reaches the product detail page, it is clear what that person desires, regardless of the segment the customer falls into. However, don’t disregard campaign-based promotions completely. A campaign targeted to all customers but featuring rule-driven promotions tied to the product can be effective. Click here to learn more about merchandizing techniques so what your customer sees if half full and not half empty.

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• Less Can Be More In E-Commerce

  - by Michael Hylton

  Today’s consumers are inundated with product choices and vendors. Visit your favorite electronics retailer and see the vast assortment of flat panel televisions. Or the variety of detergents at the supermarket. All of this can be daunting for the average consumer who is looking for the products and services that interest them.  In a study titled “Choice is Demotivating: Can One Desire Too Much of a Good Thing”, the author, Sheena Iyengar found that participants actually reported greater subsequent satisfaction with their selections and wrote better essays when their original set of options had been limited. The same can be said for e-commerce and your website. Being able to quickly convert shoppers into buyers with effective merchandising is what makes leading businesses successful. You want to engage each individual visitor with the most-relevant content to drive higher conversions and order values while decreasing abandonment, but predicting what will resonate with each customer is difficult. In a world of choices, online merchandizing tools can help personalize, streamline, and refine what your customers view when they browse your online catalog. The key to being effective is to align your products and content as closely as possible with the customer’s needs. The goal on the home page is to promote your brand and push visitors farther into the site. The home page is often the starting point for repeat customers as well as for new visitors hoping to address their current product needs. As the customer selects different filters and narrows the choices, valuable information is being provided to the retailer about the customer’s current need—regardless of previous search behavior or what other customers with a similar demographic profile have purchased. Together with search pages, category browse pages are among the primary options available to customers as a means of finding products on your site. Once a customer reaches the product detail page, it is clear what that person desires, regardless of the segment the customer falls into. However, don’t disregard campaign-based promotions completely. A campaign targeted to all customers but featuring rule-driven promotions tied to the product can be effective. Click here to learn more about merchandizing techniques so what your customer sees if half full and not half empty.

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• Why would more CPU cores on virtual machine slow compile times?

  - by Sid

  [edit#2] If anyone from VMWare can hit me up with a copy of VMWare Fusion, I'd be more than happy to do the same as a VirtualBox vs VMWare comparison. Somehow I suspect the VMWare hypervisor will be better tuned for hyperthreading (see my answer too) I'm seeing something curious. As I increase the number of cores on my Windows 7 x64 virtual machine, the overall compile time increases instead of decreasing. Compiling is usually very well suited for parallel processing as in the middle part (post dependency mapping) you can simply call a compiler instance on each of your .c/.cpp/.cs/whatever file to build partial objects for the linker to take over. So I would have imagined that compiling would actually scale very well with # of cores. But what I'm seeing is: 8 cores: 1.89 sec 4 cores: 1.33 sec 2 cores: 1.24 sec 1 core: 1.15 sec Is this simply a design artifact due to a particular vendor's hypervisor implementation (type2:virtualbox in my case) or something more pervasive across more VMs to make hypervisor implementations more simpler? With so many factors, I seem to be able to make arguments both for and against this behavior - so if someone knows more about this than me, I'd be curious to read your answer. Thanks Sid [edit:addressing comments] @MartinBeckett: Cold compiles were discarded. @MonsterTruck: Couldn't find an opensource project to compile directly. Would be great but can't screwup my dev env right now. @Mr Lister, @philosodad: Have 8 hw threads, using VirtualBox, so should be 1:1 mapping without emulation @Thorbjorn: I have 6.5GB for the VM and a smallish VS2012 project - it's quite unlikely that I'm swapping in/out trashing the page file. @All: If someone can point to an open source VS2010/VS2012 project, that might be a better community reference than my (proprietary) VS2012 project. Orchard and DNN seem to need environment tweaking to compile in VS2012. I really would like to see if someone with VMWare Fusion also sees this (for VMWare vs VirtualBox compartmentalization) Test details: Hardware: Macbook Pro Retina CPU : Core i7 @ 2.3Ghz (quad core, hyper threaded = 8 cores in windows task manager) Memory : 16 GB Disk : 256GB SSD Host OS: Mac OS X 10.8 VM type: VirtualBox 4.1.18 (type 2 hypervisor) Guest OS: Windows 7 x64 SP1 Compiler: VS2012 compiling a solution with 3 C# Azure projects Compile times measure by VS2012 plugin called 'VSCommands' All tests run 5 times, first 2 runs discarded, last 3 averaged

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• Best Creational Pattern for loggers in a multi-threaded system?

  - by Dipan Mehta

  This is a follow up question on my past questions : Concurrency pattern of logger in multithreaded application As suggested by others, I am putting this question separately. As the learning from the last question. In a multi-threaded environment, the logger should be made thread safe and probably asynchronous (where in messages are queued while a background thread does writing releasing the requesting object thread). The logger could be signleton or it can be a per-group logger which is a generalization of the above. Now, the question that arise is how does logger should be assigned to the object? There are two options I can think of: 1. Object requesting for the logger: Should each of the object call some global API such as get_logger()? Such an API returns "the" singleton or the group logger. However, I feel this involves assumption about the Application environment to implement the logger -which I think is some kind of coupling. If the same object needs to be used by other application - this new application also need to implement such a method. 2. Assign logger through some known API The other alternative approach is to create a kind of virtual class which is implemented by application based on App's own structure and assign the object sometime in the constructor. This is more generalized method. Unfortunately, when there are so many objects - and rather a tree of objects passing on the logger objects to each level is quite messy. My question is there a better way to do this? If you need to pick any one of the above, which approach is would you pick and why? Other questions remain open about how to configure them: How do objects' names or ID are assigned so that will be used for printing on the log messages (as the module names) How do these objects find the appropriate properties (such as log levels, and other such parameters) In the first approach, the central API needs to deal with all this varieties. In the second approach - there needs to be additional work. Hence, I want to understand from the real experience of people, as to how to write logger effectively in such an environment.

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• Programming Language, Turing Completeness and Turing Machine

  - by Amumu

  A programming language is said to be Turing Completeness if it can successfully simulate a universal TM. Let's take functional programming language for example. In functional programming, function has highest priority over anything. You can pass functions around like any primitives or objects. This is called first class function. In functional programming, your function does not produce side effect i.e. output strings onto screen, change the state of variables outside of its scope. Each function has a copy of its own objects if the objects are passed from the outside, and the copied objects are returned once the function finishes its job. Each function written purely in functional style is completely independent to anything outside of it. Thus, the complexity of the overall system is reduced. This is referred as referential transparency. In functional programming, each function can have its local variables kept its values even after the function exits. This is done by the garbage collector. The value can be reused the next time the function is called again. This is called memoization. A function usually should solve only one thing. It should model only one algorithm to answer a problem. Do you think that a function in a functional language with above properties simulate a Turing Machines? Functions (= algorithms = Turing Machines) are able to be passed around as input and returned as output. TM also accepts and simulate other TMs Memoization models the set of states of a Turing Machine. The memorized variables can be used to determine states of a TM (i.e. which lines to execute, what behavior should it take in a give state ...). Also, you can use memoization to simulate your internal tape storage. In language like C/C++, when a function exits, you lose all of its internal data (unless you store it elsewhere outside of its scope). The set of symbols are the set of all strings in a programming language, which is the higher level and human-readable version of machine code (opcode) Start state is the beginning of the function. However, with memoization, start state can be determined by memoization or if you want, switch/if-else statement in imperative programming language. But then, you can't Final accepting state when the function returns a value, or rejects if an exception happens. Thus, the function (= algorithm = TM) is decidable. Otherwise, it's undecidable. I'm not sure about this. What do you think? Is my thinking true on all of this? The reason I bring function in functional programming because I think it's closer to the idea of TM. What experience with other programming languages do you have which make you feel the idea of TM and the ideas of Computer Science in general? Can you specify how you think?

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• How can I solve the same problems a CB-architecture is trying to solve without using hacks? [on hold]

  - by Jefffrey

  A component based system's goal is to solve the problems that derives from inheritance: for example the fact that some parts of the code (that are called components) are reused by very different classes that, hypothetically, would lie in a very different branch of the inheritance tree. That's a very nice concept, but I've found out that CBS is often hard to accomplish without using ugly hacks. Implementations of this system are often far from clean. But I don't want to discuss this any further. My question is: how can I solve the same problems a CBS try to solve with a very clean interface? (possibly with examples, there are a lot of abstract talks about the "perfect" design already). Here's an example I was going for before realizing I was just reinventing inheritance again: class Human { public: Position position; Movement movement; Sprite sprite; // other human specific components }; class Zombie { Position position; Movement movement; Sprite sprite; // other zombie specific components }; After writing that I realized I needed an interface, otherwise I would have needed N containers for N different types of objects (or to use boost::variant to gather them all together). So I've thought of polymorphism (move what systems do in a CBS design into class specific functions): class Entity { public: virtual void on_event(Event) {} // not pure virtual on purpose virtual void on_update(World) {} virtual void on_draw(Window) {} }; class Human { private: Position position; Movement movement; Sprite sprite; public: virtual void on_event(Event) { ... } virtual void on_update(World) { ... } virtual void on_draw(Window) { ... } }; class Zombie { private: Position position; Movement movement; Sprite sprite; public: virtual void on_event(Event) { ... } virtual void on_update(World) { ... } virtual void on_draw(Window) { ... } }; Which was nice, except for the fact that now the outside world would not even be able to know where a Human is positioned (it does not have access to its position member). That would be useful to track the player position for collision detection or if on_update the Zombie would want to track down its nearest human to move towards him. So I added const Position& get_position() const; to both the Zombie and Human classes. And then I realized that both functionality were shared, so it should have gone to the common base class: Entity. Do you notice anything? Yes, with that methodology I would have a god Entity class full of common functionality (which is the thing I was trying to avoid in the first place).

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• Some More New ADF Features in JDeveloper 11.1.2

  - by Steven Davelaar

  The official list of new features in JDeveloper 11.1.2 is documented here. While playing with JDeveloper 11.1.2 and scanning the web user interface developer's guide for 11.1.2, I noticed some additional new features in ADF Faces, small but might come in handy:  You can use the af:formatString and af:formatNamed constructs in EL expressions to use substituation variables. For example: <af:outputText value="#{af:formatString('The current user is: {0}',someBean.currentUser)}"/> See section 3.5.2 in web user interface guide for more info. A new ADF Faces Client Behavior tag: af:checkUncommittedDataBehavior. See section 20.3 in web user interface guide for more info. For this tag to work, you also need to set the  uncommittedDataWarning  property on the af:document tag. And this property has quite some issues as you can read here. I did a quick test, the alert is shown for a button that is on the same page, however, if you have a menu in a shell page with dynamic regions, then clicking on another menu item does not raise the alert if you have pending changes in the currently displayed region. For now, the JHeadstart implementation of pending changes still seems the best choice (will blog about that soon). New properties on the af:document tag: smallIconSource creates a so-called favicon that is displayed in front of the URL in the browser address bar. The largeIconSource property specifies the icon used by a mobile device when bookmarking the page to the home page. See section 9.2.5 in web user interface guide for more info. Also notice the failedConnectionText property which I didn't know but was already available in JDeveloper 11.1.1.4. The af:showDetail tag has a new property handleDisclosure which you can set to client for faster rendering. In JDeveloper 11.1.1.x, an expression like #{bindings.JobId.inputValue} would return the internal list index number when JobId was a list binding. To get the actual JobId attribute value, you needed to use #{bindings.JobId.attributeValue}. In JDeveloper 11.1.2 this is no longer needed, the #{bindings.JobId.inputValue} expression will return the attribute value corresponding with the selected index in the choice list. Did you discover other "hidden" new features? Please add them as comment to this blog post so everybody can benefit. 

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• Samba fails to install

  - by jschoen

  I am running XBMC, which is built around Ubuntu 10.04. It does not come with samba pre-installed, and I need to share some media with a couple other boxes. I followed the Think Geek directions found here. I had it all set up a couple days ago, and thought I was in the clear. I rebooted this evening and when it came back up Samba was not started. I determined this by trying access the samba shares, and it would return there was an connecting to the server. I can ssh into it, so I know it is connected. In my inifinite wisdom, I figured I just messed something up and would just uninstall and reinstall. So I did: sudo apt-get purge samba and sudo apt-get purge smbfs. Then tried to follow the tutorial above again. The what I get after running sudo apt-get install samba smbfs is Reading package lists... Done Building dependency tree Reading state information... Done Suggested packages: openbsd-inetd inet-superserver smbldap-tools ldb-tools ufw smbclient The following NEW packages will be installed: samba smbfs 0 upgraded, 2 newly installed, 0 to remove and 5 not upgraded. Need to get 0B/8,131kB of archives. After this operation, 22.6MB of additional disk space will be used. Preconfiguring packages ... Selecting previously deselected package samba. (Reading database ... 57098 files and directories currently installed.) Unpacking samba (from .../samba_2%3a3.4.7~dfsg-1ubuntu3.2_i386.deb)... Selecting previously deselected package smbfs. Unpacking smbfs (from .../smbfs_2%3a3.4.7~dfsg-1ubuntu3.2_i386.deb) ... Processing triggers for ureadahead ... Setting up samba (2:3.4.7~dfsg-1ubuntu3.2) ... Generating /etc/default/samba... update-alternatives: using /usr/bin/smbstatus.samba3 to provide /usr/bin/smbstatus (smbstatus) in auto mode. smbd start/running, process 2963 **start: Job failed to start** Setting up smbfs (2:3.4.7~dfsg-1ubuntu3.2) ... The bold is my own emphasis. So I am not sure what I messed up here, or how to get back to where it was. Though I am pretty sure I made it worse than it is. I found where the logs are located, /var/logs, and found this line that seems to be the culprit. Jan 29 11:59:34 XBMCLive smbd[2806]: error opening config file So it seems to not create the configuration files. Is there a way to get samba to try to recreate them again?

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• Error while removing the new kernel 2.6.37

  - by Tarek

  Hi! I tried to install the new kernel but something went wrong and I'm trying to remove it now. The error massege is: mhd@Tarek-Laptop:~$ sudo apt-get install -f Reading package lists... Done Building dependency tree Reading state information... Done The following packages will be REMOVED: linux-image-2.6.37-020637-generic 0 upgraded, 0 newly installed, 1 to remove and 9 not upgraded. 1 not fully installed or removed. After this operation, 111MB disk space will be freed. Do you want to continue [Y/n]? y (Reading database ... 188780 files and directories currently installed.) Removing linux-image-2.6.37-020637-generic ... Examining /etc/kernel/postrm.d . run-parts: executing /etc/kernel/postrm.d/initramfs-tools 2.6.37-020637-generic /boot/vmlinuz-2.6.37-020637-generic run-parts: executing /etc/kernel/postrm.d/zz-update-grub 2.6.37-020637-generic /boot/vmlinuz-2.6.37-020637-generic /etc/default/grub: 33: Syntax error: EOF in backquote substitution run-parts: /etc/kernel/postrm.d/zz-update-grub exited with return code 2 Failed to process /etc/kernel/postrm.d at /var/lib/dpkg/info/linux-image-2.6.37-020637-generic.postrm line 328. dpkg: error processing linux-image-2.6.37-020637-generic (--remove): subprocess installed post-removal script returned error exit status 1 Errors were encountered while processing: linux-image-2.6.37-020637-generic E: Sub-process /usr/bin/dpkg returned an error code (1) The previous unsloved error is on this bug. This is my grub configuration file: # If you change this file, run 'update-grub' afterwards to update # /boot/grub/grub.cfg. GRUB_DEFAULT=0 #GRUB_HIDDEN_TIMEOUT=0 GRUB_HIDDEN_TIMEOUT_QUIET=true GRUB_TIMEOUT=10 GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian` RUB_CMDLINE_LINUX_DEFAULT="quiet splash nomodeset video=uvesafb:mode_option=1024x768-24,mtrr=3,scroll=ywrap" video=uvesafb:mode_option=>>1024x768-24<<,mtrr=3,scroll=ywrap" GRUB_CMDLINE_LINUX=" vga=792 splash" # Uncomment to enable BadRAM filtering, modify to suit your needs # This works with Linux (no patch required) and with any kernel that obtains # the memory map information from GRUB (GNU Mach, kernel of FreeBSD ...) #GRUB_BADRAM="0x01234567,0xfefefefe,0x89abcdef,0xefefefef" # Uncomment to disable graphical terminal (grub-pc only) #GRUB_TERMINAL=console # The resolution used on graphical terminal # note that you can use only modes which your graphic card supports via VBE # you can see them in real GRUB with the command `vbeinfo' GRUB_GFXMODE=1024x768-24 # Uncomment if you don't want GRUB to pass "root=UUID=xxx" parameter to Linux #GRUB_DISABLE_LINUX_UUID=true # Uncomment to disable generation of recovery mode menu entries #GRUB_DISABLE_LINUX_RECOVERY="true" # Uncomment to get a beep at grub start #GRUB_INIT_TUNE="480 440 1" thank you for answering.

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• Would someone please explain Octree Collisions to me?

  - by A-Type

  I've been reading everything I can find on the subject and I feel like the pieces are just about to fall into place, but I just can't quite get it. I'm making a space game, where collisions will occur between planets, ships, asteroids, and the sun. Each of these objects can be subdivided into 'chunks', which I have implemented to speed up rendering (the vertices can and will change often at runtime, so I've separated the buffers). These subdivisions also have bounding primitives to test for collision. All of these objects are made of blocks (yeah, it's that kind of game). Blocks can also be tested for rough collisions, though they do not have individual bounding primitives for memory reasons. I think the rough testing seems to be sufficient, though. So, collision needs to be fairly precise; at block resolution. Some functions rely on two blocks colliding. And, of course, attacking specific blocks is important. Now what I am struggling with is filtering my collision pairs. As I said, I've read a lot about Octrees, but I'm having trouble applying it to my situation as many tutorials are vague with very little code. My main issues are: Are Octrees recalculated each frame, or are they stored in memory and objects are shuffled into different divisions as they move? Despite all my reading I still am not clear on this... the vagueness of it all has been frustrating. How far do Octrees subdivide? Planets in my game are quite large, while asteroids are smaller. Do I subdivide to the size of the planet, or asteroid (where planet is in multiple divisions)? Or is the limit something else entirely, like number of elements in the division? Should I load objects into the octrees as 'chunks' or in the whole, then break into chunks later? This could be specific to my implementation, I suppose. I was going to ask about how big my root needed to be, but I did manage to find this question, and the second answer seems sufficient for me. I'm afraid I don't really get what he means by adding new nodes and doing subdivisions upon adding new objects, probably because I'm confused about whether the tree is maintained in memory or recalculated per-frame.

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• How to Remove Extensions From, and Force the Trailing Slash at the End of URLs?

  - by Kronbernkzion

  Example of current file structure: example.com/foo.php example.com/bar.html example.com/directory/ example.com/directory/foo.php example.com/directory/bar.html example.com/cgi-bin/directory/foo.cgi I would like to remove HTML, PHP and CGI extensions from, and then force the trailing slash at the end of URLs. So, it could look like this: example.com/foo/ example.com/bar/ example.com/directory/ example.com/directory/foo/ example.com/directory/bar/ example.com/cgi-bin/directory/foo/ I am very frustrated because I've searched for 17 hours straight for solution and visited more than a few hundred pages on various blogs and forums. I'm not joking. So I think I've done my research. Here is the code that sits in my .htaccess file right now: RewriteCond %{REQUEST_FILENAME} !-d RewriteCond %{REQUEST_FILENAME}\.html -f RewriteRule ^(([^/]+/)*[^./]+)/$ $1.html RewriteCond %{REQUEST_FILENAME} !-f RewriteCond %{REQUEST_FILENAME} !-d RewriteCond %{REQUEST_URI} !(\.[a-zA-Z0-9]|/)$ RewriteRule (.*)$ /$1/ [R=301,L] As you can see, this code only removes .html (and I'm not very happy with it because I think it could be done a lot simpler). I can remove the extension from PHP files when I rename them to .html through .htaccess, but that's not what I want. I want to remove it straight. This is the first thing I don't know how to do. The second thing is actually very annoying. My .htaccess file with code above, adds .html/ to every string entered after example.com/directory/foo/. So if I enter example.com/directory/foo/bar (obviously /bar doesn't exist since foo is a file), instead of just displaying message that page is not found, it converts it to example.com/directory/foo/bar.html/, then searches for a file for a few seconds and then displays the not found message. This, of course, is bad behavior. So, once again, I need the code in .htaccess to do the following things: Remove .html extension Remove .php extension Remove .cgi extension Force the trailing slash at the end of URLs Requests should behave correctly (no adding trailing slashes or extensions to strings if file or directory doesn't exist on server) Code should be as simple as possible I would very much appreciate any help. And to first person that gives me the solution, I'll send two $50 iTunes Store gift cards for US store. If this offends anyone, I am truly sorry and I apologize. Thanks in advance.

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• How to resolve concurrent ramp collisions in 2d platformer?

  - by Shaun Inman

  A bit about the physics engine: Bodies are all rectangles. Bodies are sorted at the beginning of every update loop based on the body-in-motion's horizontal and vertical velocity (to avoid sticky walls/floors). Solid bodies are resolved by testing the body-in-motion's new X with the old Y and adjusting if necessary before testing the new X with the new Y, again adjusting if necessary. Works great. Ramps (rectangles with a flag set indicating bottom-left, bottom-right, etc) are resolved by calculating the ratio of penetration along the x-axis and setting a new Y accordingly (with some checks to make sure the body-in-motion isn't attacking from the tall or flat side, in which case the ramp is treated as a normal rectangle). This also works great. Side-by-side ramps, eg. \/ and /\, work fine but things get jittery and unpredictable when a top-down ramp is directly above a bottom-up ramp, eg. < or > or when a bottom-up ramp runs right up to the ceiling/top-down ramp runs right down to the floor. I've been able to lock it down somewhat by detecting whether the body-in-motion hadFloor when also colliding with a top-down ramp or hadCeiling when also colliding with a bottom-up ramp then resolving by calculating the ratio of penetration along the y-axis and setting the new X accordingly (the opposite of the normal behavior). But as soon as the body-in-motion jumps the hasFloor flag becomes false, the first ramp resolution pushes the body into collision with the second ramp and collision resolution becomes jittery again for a few frames. I'm sure I'm making this more complicated than it needs to be. Can anyone recommend a good resource that outlines the best way to address this problem? (Please don't recommend I use something like Box2d or Chipmunk. Also, "redesign your levels" isn't an answer; the body-in-motion may at times be riding another body-in-motion, eg. a platform, that pushes it into a ramp so I'd like to be able to resolve this properly.) Thanks!

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• Best way to implement a simple bullet trajectory

  - by AirieFenix

  I searched and searched and although it's a fair simple question, I don't find the proper answer but general ideas (which I already have). I have a top-down game and I want to implement a gun which shoots bullets that follow a simple path (no physics nor change of trajectory, just go from A to B thing). a: vector of the position of the gun/player. b: vector of the mouse position (cross-hair). w: the vector of the bullet's trajectory. So, w=b-a. And the position of the bullet = [x=x0+speed*time*normalized w.x , y=y0+speed*time * normalized w.y]. I have the constructor: public Shot(int shipX, int shipY, int mouseX, int mouseY) { //I get mouse with Gdx.input.getX()/getY() ... this.shotTime = TimeUtils.millis(); this.posX = shipX; this.posY = shipY; //I used aVector = aVector.nor() here before but for some reason didn't work float tmp = (float) (Math.pow(mouseX-shipX, 2) + Math.pow(mouseY-shipY, 2)); tmp = (float) Math.sqrt(Math.abs(tmp)); this.vecX = (mouseX-shipX)/tmp; this.vecY = (mouseY-shipY)/tmp; } And here I update the position and draw the shot: public void drawShot(SpriteBatch batch) { this.lifeTime = TimeUtils.millis() - this.shotTime; //position = positionBefore + v*t this.posX = this.posX + this.vecX*this.lifeTime*speed*Gdx.graphics.getDeltaTime(); this.posY = this.posY + this.vecY*this.lifeTime*speed*Gdx.graphics.getDeltaTime(); ... } Now, the behavior of the bullet seems very awkward, not going exactly where my mouse is (it's like the mouse is 30px off) and with a random speed. I know I probably need to open the old algebra book from college but I'd like somebody says if I'm in the right direction (or points me to it); if it's a calculation problem, a code problem or both. Also, is it possible that Gdx.input.getX() gives me non-precise position? Because when I draw the cross-hair it also draws off the cursor position. Sorry for the long post and sorry if it's a very basic question. Thanks!

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• What Precalculus knowledge is required before learning Discrete Math Computer Science topics?

  - by Ein Doofus

  Below I've listed the chapters from a Precalculus book as well as the author recommended Computer Science chapters from a Discrete Mathematics book. Although these chapters are from two specific books on these subjects I believe the topics are generally the same between any Precalc or Discrete Math book. What Precalculus topics should one know before starting these Discrete Math Computer Science topics?: Discrete Mathematics CS Chapters 1.1 Propositional Logic 1.2 Propositional Equivalences 1.3 Predicates and Quantifiers 1.4 Nested Quantifiers 1.5 Rules of Inference 1.6 Introduction to Proofs 1.7 Proof Methods and Strategy 2.1 Sets 2.2 Set Operations 2.3 Functions 2.4 Sequences and Summations 3.1 Algorithms 3.2 The Growths of Functions 3.3 Complexity of Algorithms 3.4 The Integers and Division 3.5 Primes and Greatest Common Divisors 3.6 Integers and Algorithms 3.8 Matrices 4.1 Mathematical Induction 4.2 Strong Induction and Well-Ordering 4.3 Recursive Definitions and Structural Induction 4.4 Recursive Algorithms 4.5 Program Correctness 5.1 The Basics of Counting 5.2 The Pigeonhole Principle 5.3 Permutations and Combinations 5.6 Generating Permutations and Combinations 6.1 An Introduction to Discrete Probability 6.4 Expected Value and Variance 7.1 Recurrence Relations 7.3 Divide-and-Conquer Algorithms and Recurrence Relations 7.5 Inclusion-Exclusion 8.1 Relations and Their Properties 8.2 n-ary Relations and Their Applications 8.3 Representing Relations 8.5 Equivalence Relations 9.1 Graphs and Graph Models 9.2 Graph Terminology and Special Types of Graphs 9.3 Representing Graphs and Graph Isomorphism 9.4 Connectivity 9.5 Euler and Hamilton Ptahs 10.1 Introduction to Trees 10.2 Application of Trees 10.3 Tree Traversal 11.1 Boolean Functions 11.2 Representing Boolean Functions 11.3 Logic Gates 11.4 Minimization of Circuits 12.1 Language and Grammars 12.2 Finite-State Machines with Output 12.3 Finite-State Machines with No Output 12.4 Language Recognition 12.5 Turing Machines Precalculus Chapters R.1 The Real-Number System R.2 Integer Exponents, Scientific Notation, and Order of Operations R.3 Addition, Subtraction, and Multiplication of Polynomials R.4 Factoring R.5 Rational Expressions R.6 Radical Notation and Rational Exponents R.7 The Basics of Equation Solving 1.1 Functions, Graphs, Graphers 1.2 Linear Functions, Slope, and Applications 1.3 Modeling: Data Analysis, Curve Fitting, and Linear Regression 1.4 More on Functions 1.5 Symmetry and Transformations 1.6 Variation and Applications 1.7 Distance, Midpoints, and Circles 2.1 Zeros of Linear Functions and Models 2.2 The Complex Numbers 2.3 Zeros of Quadratic Functions and Models 2.4 Analyzing Graphs of Quadratic Functions 2.5 Modeling: Data Analysis, Curve Fitting, and Quadratic Regression 2.6 Zeros and More Equation Solving 2.7 Solving Inequalities 3.1 Polynomial Functions and Modeling 3.2 Polynomial Division; The Remainder and Factor Theorems 3.3 Theorems about Zeros of Polynomial Functions 3.4 Rational Functions 3.5 Polynomial and Rational Inequalities 4.1 Composite and Inverse Functions 4.2 Exponential Functions and Graphs 4.3 Logarithmic Functions and Graphs 4.4 Properties of Logarithmic Functions 4.5 Solving Exponential and Logarithmic Equations 4.6 Applications and Models: Growth and Decay 5.1 Systems of Equations in Two Variables 5.2 System of Equations in Three Variables 5.3 Matrices and Systems of Equations 5.4 Matrix Operations 5.5 Inverses of Matrices 5.6 System of Inequalities and Linear Programming 5.7 Partial Fractions 6.1 The Parabola 6.2 The Circle and Ellipse 6.3 The Hyperbola 6.4 Nonlinear Systems of Equations

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• iwlwifi on lenovo z570 disabled by hardware switch

  - by Kevin Gallagher

  It was working fine with windows 7. The hardware switch is not disabled. I've toggled it back and forth dozens of times. The wifi light never turns on and it always lists as hardware disabled. I have the latest updates installed. I've been searching for solutions, but none of them seem to work for me. I've tried removing acer-wmi. I've tried setting 11n_disable=1. I've tried resetting the bios. I've tried using rfkill to unblock (only removes soft block). I've rebooted dozens of times. The wifi light turns off as soon as grub loads. Edit: I have a usb edimax wireless nic. It shows hardware disabled as well (although rfkill lists as unblocked). If I unload iwlwifi the usb nic works fine. uname -a `Linux xxx-Ideapad-Z570 3.2.0-55-generic #85-Ubuntu SMP Wed Oct 2 12:29:27 UTC 2013 x86_64 x86_64 x86_64 GNU/Linu`x rfkill list 19: phy18: Wireless LAN Soft blocked: no Hard blocked: yes dmesg [43463.022996] Intel(R) Wireless WiFi Link AGN driver for Linux, in-tree: [43463.023002] Copyright(c) 2003-2011 Intel Corporation [43463.023107] iwlwifi 0000:03:00.0: PCI INT A -> GSI 17 (level, low) -> IRQ 17 [43463.023190] iwlwifi 0000:03:00.0: setting latency timer to 64 [43463.023253] iwlwifi 0000:03:00.0: pci_resource_len = 0x00002000 [43463.023257] iwlwifi 0000:03:00.0: pci_resource_base = ffffc900057c8000 [43463.023261] iwlwifi 0000:03:00.0: HW Revision ID = 0x0 [43463.023797] iwlwifi 0000:03:00.0: irq 43 for MSI/MSI-X [43463.024013] iwlwifi 0000:03:00.0: Detected Intel(R) Centrino(R) Wireless-N 1000 BGN, REV=0x6C [43463.024250] iwlwifi 0000:03:00.0: L1 Enabled; Disabling L0S [43463.045496] iwlwifi 0000:03:00.0: device EEPROM VER=0x15d, CALIB=0x6 [43463.045501] iwlwifi 0000:03:00.0: Device SKU: 0X50 [43463.045504] iwlwifi 0000:03:00.0: Valid Tx ant: 0X1, Valid Rx ant: 0X3 [43463.045542] iwlwifi 0000:03:00.0: Tunable channels: 13 802.11bg, 0 802.11a channels [43463.045744] iwlwifi 0000:03:00.0: RF_KILL bit toggled to disable radio. [43463.047652] iwlwifi 0000:03:00.0: loaded firmware version 39.31.5.1 build 35138 [43463.047823] Registered led device: phy18-led [43463.047895] cfg80211: Ignoring regulatory request Set by core since the driver uses its own custom regulatory domain [43463.048037] ieee80211 phy18: Selected rate control algorithm 'iwl-agn-rs' [43463.055533] ADDRCONF(NETDEV_UP): wlan0: link is not ready nm-tool State: connected (global) - Device: wlan0 ---------------------------------------------------------------- Type: 802.11 WiFi Driver: iwlwifi State: unavailable Default: no HW Address: 74:E5:0B:4A:9F:C2 Capabilities: Wireless Properties WEP Encryption: yes WPA Encryption: yes WPA2 Encryption: yes Wireless Access Points lshw -C network *-network DISABLED description: Wireless interface product: Centrino Wireless-N 1000 [Condor Peak] vendor: Intel Corporation physical id: 0 bus info: pci@0000:03:00.0 logical name: wlan0 version: 00 serial: 74:e5:0b:4a:9f:c2 width: 64 bits clock: 33MHz capabilities: pm msi pciexpress bus_master cap_list ethernet physical wireless configuration: broadcast=yes driver=iwlwifi driverversion=3.2.0-55-generic firmware=39.31.5.1 build 35138 latency=0 link=no multicast=yes wireless=IEEE 802.11bg resources: irq:43 memory:f1500000-f1501fff lspci 03:00.0 Network controller: Intel Corporation Centrino Wireless-N 1000 [Condor Peak]

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• ZFS for Database Log Files

  - by user12620111

  I've been troubled by drop outs in CPU usage in my application server, characterized by the CPUs suddenly going from close to 90% CPU busy to almost completely CPU idle for a few seconds. Here is an example of a drop out as shown by a snippet of vmstat data taken while the application server is under a heavy workload. # vmstat 1  kthr      memory            page            disk          faults      cpu  r b w   swap  free  re  mf pi po fr de sr s3 s4 s5 s6   in   sy   cs us sy id  1 0 0 130160176 116381952 0 16 0 0 0 0  0  0  0  0  0 207377 117715 203884 70 21 9  12 0 0 130160160 116381936 0 25 0 0 0 0 0  0  0  0  0 200413 117162 197250 70 20 9  11 0 0 130160176 116381920 0 16 0 0 0 0 0  0  1  0  0 203150 119365 200249 72 21 7  8 0 0 130160176 116377808 0 19 0 0 0 0  0  0  0  0  0 169826 96144 165194 56 17 27  0 0 0 130160176 116377800 0 16 0 0 0 0  0  0  0  0  1 10245 9376 9164 2  1 97  0 0 0 130160176 116377792 0 16 0 0 0 0  0  0  0  0  2 15742 12401 14784 4 1 95  0 0 0 130160176 116377776 2 16 0 0 0 0  0  0  1  0  0 19972 17703 19612 6 2 92  14 0 0 130160176 116377696 0 16 0 0 0 0 0  0  0  0  0 202794 116793 199807 71 21 8  9 0 0 130160160 116373584 0 30 0 0 0 0  0  0 18  0  0 203123 117857 198825 69 20 11 This behavior occurred consistently while the application server was processing synthetic transactions: HTTP requests from JMeter running on an external machine. I explored many theories trying to explain the drop outs, including: Unexpected JMeter behavior Network contention Java Garbage Collection Application Server thread pool problems Connection pool problems Database transaction processing Database I/O contention Graphing the CPU %idle led to a breakthrough: Several of the drop outs were 30 seconds apart. With that insight, I went digging through the data again and looking for other outliers that were 30 seconds apart. In the database server statistics, I found spikes in the iostat "asvc_t" (average response time of disk transactions, in milliseconds) for the disk drive that was being used for the database log files. Here is an example:                     extended device statistics     r/s    w/s   kr/s   kw/s wait actv wsvc_t asvc_t  %w  %b device     0.0 2053.6    0.0 8234.3  0.0  0.2    0.0    0.1   0  24 c3t60080E5...F4F6d0s0     0.0 2162.2    0.0 8652.8  0.0  0.3    0.0    0.1   0  28 c3t60080E5...F4F6d0s0     0.0 1102.5    0.0 10012.8  0.0  4.5    0.0    4.1   0  69 c3t60080E5...F4F6d0s0     0.0   74.0    0.0 7920.6  0.0 10.0    0.0  135.1   0 100 c3t60080E5...F4F6d0s0     0.0  568.7    0.0 6674.0  0.0  6.4    0.0   11.2   0  90 c3t60080E5...F4F6d0s0     0.0 1358.0    0.0 5456.0  0.0  0.6    0.0    0.4   0  55 c3t60080E5...F4F6d0s0     0.0 1314.3    0.0 5285.2  0.0  0.7    0.0    0.5   0  70 c3t60080E5...F4F6d0s0 Here is a little more information about my database configuration: The database and application server were running on two different SPARC servers. Storage for the database was on a storage array connected via 8 gigabit Fibre Channel Data storage and log file were on different physical disk drives Reliable low latency I/O is provided by battery backed NVRAM Highly available: Two Fibre Channel links accessed via MPxIO Two Mirrored cache controllers The log file physical disks were mirrored in the storage device Database log files on a ZFS Filesystem with cutting-edge technologies, such as copy-on-write and end-to-end checksumming Why would I be getting service time spikes in my high-end storage? First, I wanted to verify that the database log disk service time spikes aligned with the application server CPU drop outs, and they did: At first, I guessed that the disk service time spikes might be related to flushing the write through cache on the storage device, but I was unable to validate that theory. After searching the WWW for a while, I decided to try using a separate log device: # zpool add ZFS-db-41 log c3t60080E500017D55C000015C150A9F8A7d0 The ZFS log device is configured in a similar manner as described above: two physical disks mirrored in the storage array. This change to the database storage configuration eliminated the application server CPU drop outs: Here is the zpool configuration: # zpool status ZFS-db-41   pool: ZFS-db-41  state: ONLINE  scan: none requested config:         NAME                                     STATE         ZFS-db-41                                ONLINE           c3t60080E5...F4F6d0  ONLINE         logs           c3t60080E5...F8A7d0  ONLINE Now, the I/O spikes look like this:                     extended device statistics                  r/s    w/s   kr/s   kw/s wait actv wsvc_t asvc_t  %w  %b device     0.0 1053.5    0.0 4234.1  0.0  0.8    0.0    0.7   0  75 c3t60080E5...F8A7d0s0                     extended device statistics                  r/s    w/s   kr/s   kw/s wait actv wsvc_t asvc_t  %w  %b device     0.0 1131.8    0.0 4555.3  0.0  0.8    0.0    0.7   0  76 c3t60080E5...F8A7d0s0                     extended device statistics                  r/s    w/s   kr/s   kw/s wait actv wsvc_t asvc_t  %w  %b device     0.0 1167.6    0.0 4682.2  0.0  0.7    0.0    0.6   0  74 c3t60080E5...F8A7d0s0     0.0  162.2    0.0 19153.9  0.0  0.7    0.0    4.2   0  12 c3t60080E5...F4F6d0s0                     extended device statistics                  r/s    w/s   kr/s   kw/s wait actv wsvc_t asvc_t  %w  %b device     0.0 1247.2    0.0 4992.6  0.0  0.7    0.0    0.6   0  71 c3t60080E5...F8A7d0s0     0.0   41.0    0.0   70.0  0.0  0.1    0.0    1.6   0   2 c3t60080E5...F4F6d0s0                     extended device statistics                  r/s    w/s   kr/s   kw/s wait actv wsvc_t asvc_t  %w  %b device     0.0 1241.3    0.0 4989.3  0.0  0.8    0.0    0.6   0  75 c3t60080E5...F8A7d0s0                     extended device statistics                  r/s    w/s   kr/s   kw/s wait actv wsvc_t asvc_t  %w  %b device     0.0 1193.2    0.0 4772.9  0.0  0.7    0.0    0.6   0  71 c3t60080E5...F8A7d0s0 We can see the steady flow of 4k writes to the ZIL device from O_SYNC database log file writes. The spikes are from flushing the transaction group. Like almost all problems that I run into, once I thoroughly understand the problem, I find that other people have documented similar experiences. Thanks to all of you who have documented alternative approaches. Saved for another day: now that the problem is obvious, I should try "zfs:zfs_immediate_write_sz" as recommended in the ZFS Evil Tuning Guide. References: The ZFS Intent Log Solaris ZFS, Synchronous Writes and the ZIL Explained ZFS Evil Tuning Guide: Cache Flushes ZFS Evil Tuning Guide: Tuning ZFS for Database Performance

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• Creating classed in JavaScript

  - by Renso

  Goal:Creating class instances in JavaScript is not available since you define "classes" in js with object literals. In order to create classical classes like you would in c#, ruby, java, etc, with inheritance and instances.Rather than typical class definitions using object literals, js has a constructor function and the NEW operator that will allow you to new-up a class and optionally provide initial properties to initialize the new object with.The new operator changes the function's context and behavior of the return statement.var Person = function(name) {   this.name = name;};   //Init the personvar dude= new Person("renso");//Validate the instanceassert(dude instanceof Person);When a constructor function is called with the new keyword, the context changes from global window to a new and empty context specific to the instance; "this" will refer in this case to the "dude" context.Here is class pattern that you will need to define your own CLASS emulation library:var Class = function() {   var _class = function() {      this.init.apply(this, arguments);   };   _class.prototype.init = function(){};   return _class;}var Person a new Class();Person.prototype.init = function() {};var person = new Person;In order for the class emulator to support adding functions and properties to static classes as well as object instances of People, change the emulator:var Class = function() {   var _class = function() {      this.init.apply(this, arguments);   };   _class.prototype.init = function(){};   _class.fn = _class.prototype;   _class.fn.parent = _class;   //adding class properties   _class.extend = function(obj) {      var extended = obj.extended;      for(var i in obj) {         _class[i] = obj[i];      };      if(extended) extended(_class);   };   //adding new instances   _class.include = function(obj) {      var included = obj.included;      for(var i in obj) {         _class.fn[i] = obj[i];      };      if(included) included(_class);   };   return _class;}Now you can use it to create and extend your own object instances://adding static functions to the class Personvar Person = new Class();Person.extend({   find: function(name) {/*....*/},      delete: function(id) {/*....*/},});//calling static function findvar person = Person.find('renso');   //adding properties and functions to the class' prototype so that they are available on instances of the class Personvar Person = new Class;Person.extend({   save: function(name) {/*....*/},   delete: function(id) {/*....*/}});var dude = new Person;//calling instance functiondude.save('renso');

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• Pretty URL in ADF Faces of JDeveloper 11.1.2.2

  - by Frank Nimphius

  Many features planned for Oracle JDeveloper 12c find their way into current releases of Oracle JDeveloper 11g R1 and JDeveloper 11g R2. One example of such a feature is "pretty URL" - or "clean URL" as the Oracle JDeveloper 11g R2 (11.1.2.2) documentation puts it. "A.2.3.24 Clean URLs Historically, ADF Faces has used URL parameters to hold information, such as window IDs and state. However, URL parameters can prevent search engines from recognizing when URLs are actually the same, and therefore interfere with analytics. URL parameters can also interfere with bookmarking. By default, ADF Faces removes URL parameters using the HTML5 History Management API. If that API is unavailable, then session cookies are used.You can also manually configure how URL parameters are removed using the context parameter oracle.adf.view.rich.prettyURL.OPTIONS. Set the parameter to off so that no parameters are removed. Set the parameter to useHistoryApi to only use the HTML5 History Management API. If a browser does not support this API, then no parameters will be removed. Set the parameter to useCookies to use session cookies to remove parameters. If the browser does not support cookies, then no parameters will be removed." See: http://docs.oracle.com/cd/E26098_01/web.1112/e16181/ap_config.htm#ADFUI12856 So basically, what this part in the documentation says is: In JDeveloper 11g R2 (11.1.2.2), Oracle ADF Faces automatically removes its internally used dynamic parameters from the URL You can influence the setting with the prettyURL.OPTIONS context option, which however is not recommended you to do because the default behavior is able to detect if the browser client supports HTML 5 History management or not. In the latter case it the uses a session cookie and if this doesn't work, falls back to the "old" URL parameter adding. The information that is not so explicit and clearly mentioned in the documentation is that this is only for ADF Faces parameters (such as _afrLoop, Adf-Window-Id, etc.), but not the ADF controller token (_adf.ctrl-state)! Removing the ADF controller token is an enhancement request that will be implemented in Oracle JDeveloper 12c

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