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• How much overhead is there in persistent connections?

  - by nynex

  Ok so I'm musing over a little side project I want to start. Essentially its a multi-session web based FTP client. Multi-session in that you can log into several FTP servers at the same time and perform operations like moving a file from one FTP server to another. I'm doing this mainly to brush up on the new webdev technologies, particularly websockets. I'm using node.js + socket.io to keep a persistent bi-directional connection between the web browser and the web server. The web server will also have persistent connections to each FTP server the user has logged into. So if there are 100 concurrent users each logged into 5 ftp accounts, the web server will have 100 websocket connections + 500 ftp connections. Is servicing 600 connections a lot? I know it depends on the hardware resources of the server but is something like this doable on a budget? Are there more efficient means of doing something like this? I know its unlikely that this project will really get popular but I want it to scale well regardless. Thanks for any help, I've still got a lot to learn.

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• Unit testing to prove balanced tree

  - by Darrel Hoffman

  I've just built a self-balancing tree (red-black) in Java (language should be irrelevant for this question though), and I'm trying to come up with a good means of testing that it's properly balanced. I've tested all the basic tree operations, but I can't think of a way to test that it is indeed well and truly balanced. I've tried inserting a large dictionary of words, both pre-sorted and un-sorted. With a balanced tree, those should take roughly the same amount of time, but an unbalanced tree would take significantly longer on the already-sorted list. But I don't know how to go about testing for that in any reasonable, reproducible way. (I've tried doing millisecond tests on these, but there's no noticeable difference - probably because my source data is too small.) Is there a better way to be sure that the tree is really balanced? Say, by looking at the tree after it's created and seeing how deep it goes? (That is, without modifying the tree itself by adding a depth field to each node, which is just wasteful if you don't need it for anything other than testing.)

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• How to represent a graph with multiple edges allowed between nodes and edges that can selectively disappear

  - by Pops

  I'm trying to figure out what sort of data structure to use for modeling some hypothetical, idealized network usage. In my scenario, a number of users who are hostile to each other are all trying to form networks of computers where all potential connections are known. The computers that one user needs to connect may not be the same as the ones another user needs to connect, though; user 1 might need to connect computers A, B and D while user 2 might need to connect computers B, C and E. Image generated with the help of NCTM Graph Creator I think the core of this is going to be an undirected cyclic graph, with nodes representing computers and edges representing Ethernet cables. However, due to the nature of the scenario, there are a few uncommon features that rule out adjacency lists and adjacency matrices (at least, without non-trivial modifications): edges can become restricted-use; that is, if one user acquires a given network connection, no other user may use that connection in the example, the green user cannot possibly connect to computer A, but the red user has connected B to E despite not having a direct link between them in some cases, a given pair of nodes will be connected by more than one edge in the example, there are two independent cables running from D to E, so the green and blue users were both able to connect those machines directly; however, red can no longer make such a connection if two computers are connected by more than one cable, each user may own no more than one of those cables I'll need to do several operations on this graph, such as: determining whether any particular pair of computers is connected for a given user identifying the optimal path for a given user to connect target computers identifying the highest-latency computer connection for a given user (i.e. longest path without branching) My first thought was to simply create a collection of all of the edges, but that's terrible for searching. The best thing I can think to do now is to modify an adjacency list so that each item in the list contains not only the edge length but also its cost and current owner. Is this a sensible approach? Assuming space is not a concern, would it be reasonable to create multiple copies of the graph (one for each user) rather than a single graph?

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• FP for simulation and modelling

  - by heaptobesquare

  I'm about to start a simulation/modelling project. I already know that OOP is used for this kind of projects. However, studying Haskell made me consider using the FP paradigm for modelling a system of components. Let me elaborate: Let's say I have a component of type A, characterised by a set of data (a parameter like temperature or pressure,a PDE and some boundary conditions,etc.) and a component of type B, characterised by a different set of data(different or same parameter, different PDE and boundary conditions). Let's also assume that the functions/methods that are going to be applied on each component are the same (a Galerkin method for example). If I were to use an OOP approach, I would create two objects that would encapsulate each type's data, the methods for solving the PDE(inheritance would be used here for code reuse) and the solution to the PDE. On the other hand, if I were to use an FP approach, each component would be broken down to data parts and the functions that would act upon the data in order to get the solution for the PDE. This approach seems simpler to me assuming that linear operations on data would be trivial and that the parameters are constant. What if the parameters are not constant(for example, temperature increases suddenly and therefore cannot be immutable)? In OOP, the object's (mutable) state can be used. I know that Haskell has Monads for that. To conclude, would implementing the FP approach be actually simpler,less time consuming and easier to manage (add a different type of component or new method to solve the pde) compared to the OOP one? I come from a C++/Fortran background, plus I'm not a professional programmer, so correct me on anything that I've got wrong.

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• [EF + Oracle]Object Context

  - by JTorrecilla

  Prologue After EF episodes I and II, we are going to see the Object Context. What is Object Context? It is a class which manages the DB connection, and the different Entities of our model. When Visual Studio creates the EF model, like I explain previously, also generates a Class that extends ObjectContext. ObjectContext provides: - DB connection - Add, update and delete functions. - Object Sets of Entities. - State of Pending Changes. This class will give a function, for each Entity, like  Esta clase va a contar con una función, para cada entidad, del tipo “AddTo{ENTITY}({Entity_Type } value)”, which are going to add a Entity to the related ObjectSet. In addition, it has a property, for each Entity, like “ObjectSet<TEntity> Entity”, does will keep the related record set. It will be filled with the CreateObjectSet<TEntity> function of Base class (ObjectContext). What is an ObjectSet? It is a class that allows us to manage the Entity Set from a Type. It inherits from: · ObjectQuery<TEntity> · IObjectSet<TEntity> · IQueryAble<TEntity · IEnumerable<TEntity · IQueryAble · IEnumerable An ObjectSet is a class property that allows query, insert, delete and update records from a determinate Entity. In following chapters we will see how to query Entities. LazyLoadingEnabled A very important property of the Context is “LazyLoadingEnabled”. This Boolean property lets indicate if the data loading is lazy, in other words, the Object will not be created and query until not be needed. Finally In this post we have seen what the VS generated context is, some of the characteristics, and where to see Entity data. In next chapters we will see, CRUD operations, and how to query ObjectSets.

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• I'm a Subversion geek, why should I consider or not consider Mercurial or Git or any other DVCS?

  - by user2567

  I try to understand the benefits of distributed version control system (DVCS). I found Subversion Re-education and this article by Martin Fowler very useful. Mercurial and others DVCS promote a new way of working on code with changesets and local commits. It prevents from merging hell and other collaboration issues We are not affected by this as I practice continuous integration and working alone in a private branch is not an option, unless we are experimenting. We use a branch for every major version, in which we fix bugs merged from the trunk. Mercurial allows you to have lieutenants I understand this can be useful for very large projects like Linux, but I don't see the value in small and highly collaborative teams (5 to 7 people). Mercurial is faster, takes less disk space and full local copy allows faster logs & diffs operations. I'm not concerned by this either, as I didn't notice speed or space problems with SVN even with very large projects I'm working on. I'm seeking for your personal experiences and/or opinions from former SVN geeks. Especially regarding the changesets concept and overall performance boost you measured. UPDATE (12th Jan): I'm now convinced that it worth a try. UPDATE (12th Jun): I kissed Mercurial and I liked it. The taste of his cherry local commits. I kissed Mercurial just to try it. I hope my SVN Server don't mind it. It felt so wrong. It felt so right. Don't mean I'm in love tonight. FINAL UPDATE (29th Jul): I had the privilege to review Eric Sink's next book called Version Control by Example. He finished to convince me. I'll go for Mercurial.

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• 724% Return on an SFA project with Oracle Sales Cloud and Marketing Cloud combined!

  - by Richard Lefebvre

  Oracle Sales Cloud and Marketing Cloud customer Apex IT gained just that?a 724% return on investment (ROI) when it implemented these Oracle Cloud solutions in its fast-moving, rapidly-growing business. Apex IT was just announced as a winner of the Nucleus Research 11th annual Technology ROI Awards. The award, given by the analyst firm, highlights organizations that have successfully leveraged IT deployments to maximize value per dollar spent. Fast Facts: Return on Investment – 724% Payback – 2 months Average annual benefit – $91,534 Cost : Benefit Ratio – 1:48 Business Benefits In addition to the ROI and cost metrics the award calls out improvements in Apex IT’s business operations—across both Sales and Marketing teams: Improved ability to identify new opportunities and focus sales resources on higher-probability deals Reduced administration and manual lead tracking—resulting in more time selling and a net new client increase of 46% Increased campaign productivity for both Marketing and Sales, including Oracle Marketing Cloud’s automation of campaign tracking and nurture programs Improved margins with more structured and disciplined sales processes—resulting in more effective deal negotiations Read the full Apex IT ROI Case Study. You also can learn more about Apex IT’s business, including the company’s work with Oracle Sales and Marketing Cloud on behalf of its clients. You can point your prospects and customers to the CX blog for a similar recap of the Apex IT award and a link to the Case Study.

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• NFS users getting a laggy GUI expierence

  - by elzilrac

  I am setting up a system (ubuntu 12.04) that uses ldap, pam, and autofs to load users and their home folders from a remote server. One of the options for login is sitting down at the machine and starting a GUI session. Programs such as chormium (browser) that preform many read/write operations in the ~/.cache and ~/.config files are slowing down the GUI experience as well as putting strain of the NFS server that is causing other users to have problems. Ubuntu had the handy-dandy XDG_CONFIG_HOME and XDG_CACHE_HOME variables that can be set to change the default location of .cache and .config from the home folder to somewhere else. There are several places to set them, but most of them are not optimal. /etc/environment pros: will work across all shells cons: cannot use variables like $USER so that you can't make users have different new locations for .cache and .config. Every users' new location would be the same directory. /etc/bash.bashrc pros: $USER works, so you can place them in different folders cons: only gets run for bash compatible shells ~/.pam_environment pros: works regardless of shell cons: cannot use system variables (like $USER), has it's own syntax, and has to be created for every user

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• Is there a simple, flat, XML-based query-able data storage solution? [closed]

  - by alex gray

  I have been in long pursuit of an XML-based query-able data store, and despite continued searches and evaluations, I have yet to find a solution that meets the my needs, which include: Data is wholly contained within XML nodes, in flat text files. There is a "native" - or at least unobtrusive - method with which to perform Create/Read/Update/Delete (CRUD) operations onto the "schema". I would consider access via http, XHR, javascript, PHP, BASH, or PERL to be unobtrusive, dependent on the complexity of the set of dependencies. Server-side file-system reads and writes. A client-side interface element, accessible in any browser without a plug-in. Some extra, preferred (but optional) requirements include: Respond to simple SQL, or similarly syntax queries. Serve the data on a bare bones https server, with no "extra stuff", either via XMLHTTPRequest, HTTP proper, or JSON. A few thoughts: What I'm looking for may be possible via some Java server implementations, but for the sake of this question, please do not suggest that - unless it meets ALL the requirements. Java, especially on the client-side is not really an option, nor is it appealing from a development viewpoint.* I know walking the filesystem is a stretch, and I've heard it's possible with XPATH or XSLT, but as far as I know, that's not ready for primetime, nor even yet a recommendation. However the ability to recursively traverse the filesystem is needed for such a system to be of useful facility. At this point, I have basically implemented what I described via, of all things, CGI and Bash, but there has to be an easier way. Thoughts?

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• Ternary and Artificial Intelligence

  - by user2957844

  Not much of a programmer myself, however I have been thinking about the future of AI. If a fully functional AI is programmed in a binary environment as is used in current computing, would that create a bit of a black and white personality? As in just yes/no, on/off, 1/0? I will use the Skynet computer from the Terminator series as a bad analogy; it is brought online and comes to the conclusion that humanity should just be destroyed so the problem is resolved, basically its only options were; fire the missiles or not. (The films do not really go into what its moves would be after doing such a thing, but that goes into the realms of AI evolution so does not really fit with this question.) It may also have been badly programmed. Now, the human mind has been akin to a ternary system which allows our "out of the box" thinking along with all the other wonderful things our minds can do. So, would it not be more prudent to create a functional ternary system and program an AI using it so the resulting personality would be able to benefit from the third "maybe" (so to speak) option? I understand that in binary there are ways to get around the whole yes/no etc. way of things, however the basic operations are still just 1's and 0's. Again with using the above bad Skynet analogy; if it could have had that third "maybe" option as part of its core system, it may have decided to not launch due to being able to make sense of the intricacies of human nature and the politics of such a move etc. In effect, my question is; Would an AI benefit more from ternary computing as opposed to binary due to the inclusion of -1, or 2, dependent on the system ("maybe," as I call it)?

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• Call DB Stored Procedure using @NamedStoredProcedureQuery Injection

  - by anwilson

  Oracle Database Stored Procedure can be called from EJB business layer to perform complex DB specific operations. This approach will avoid overhead from frequent network hits which could impact end-user result. DB Stored Procedure can be invoked from EJB Session Bean business logic using org.eclipse.persistence.queries.StoredProcedureCall API. Using this approach requires more coding to handle the Session and Arguments of the Stored Procedure, thereby increasing effort on maintenance. EJB 3.0 introduces @NamedStoredProcedureQuery Injection to call Database Stored Procedure as NamedQueries. This blog will take you through the steps to call Oracle Database Stored Procedure using @NamedStoredProcedureQuery.EMP_SAL_INCREMENT procedure available in HR schema will be used in this sample.Create Entity from EMPLOYEES table.Add @NamedStoredProcedureQuery above @NamedQueries to Employees.java with definition as given below - @NamedStoredProcedureQuery(name="Employees.increaseEmpSal", procedureName = "EMP_SAL_INCREMENT", resultClass=void.class, resultSetMapping = "", returnsResultSet = false, parameters = { @StoredProcedureParameter(name = "EMP_ID", queryParameter = "EMPID"), @StoredProcedureParameter(name = "SAL_INCR", queryParameter = "SALINCR")} ) Observe how Stored Procedure's arguments are handled easily in  @NamedStoredProcedureQuery using @StoredProcedureParameter.Expose Entity Bean by creating a Session Facade.Business method need to be added to Session Bean to access the Stored Procedure exposed as NamedQuery. public void salaryRaise(Long empId, Long salIncrease) throws Exception { try{ Query query = em.createNamedQuery("Employees.increaseEmpSal"); query.setParameter("EMPID", empId); query.setParameter("SALINCR", salIncrease); query.executeUpdate(); } catch(Exception ex){ throw ex; } } Expose business method through Session Bean Remote Interface. void salaryRaise(Long empId, Long salIncrease) throws Exception; Session Bean Client is required to invoke the method exposed through remote interface.Call exposed method in Session Bean Client main method. final Context context = getInitialContext(); SessionEJB sessionEJB = (SessionEJB)context.lookup("Your-JNDI-lookup"); sessionEJB.salaryRaise(new Long(200), new Long(1000)); Deploy Session BeanRun Session Bean Client.Salary of Employee with Id 200 will be increased by 1000.

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• 11.10 system crashes for no apparent reason [closed]

  - by varanoid

  I'm relatively new to Linux, and while I know a fair amount about computers and programming, it certainly isn't my specialty. I have a dual boot with Windows 7, and it has been working very well for me until recently. Just randomly the computer will freeze. The last time I was smart enough to keep the System Monitor open when it happened, and it looks like at the time of freezing "bash" and a bunch of other processes that I don't recognize seem to have flooded the memory. So it looks like my memory is getting overloaded and this is what is crashing the system, but I honestly have no idea what could be doing it. Generally I have a bunch of programs running, but they don't take much RAM or CPU: Transmission, Libre Office Writer, Firefox, Empathy, and Banshee. Sometimes I also have Text Editor and Terminal open, but it crashes regardless. When it crashes, it seems that all of the programs are working fine but things like windows, the taskbar, and operations like Alt+Tab just stop working properly or at all. Sometimes the mouse and keyboard freeze and I have to power off manually. Other than that I don't know what the problem is. The only irregularity I've experienced is that I can't download "Debian package management system" even though other updates download fine.

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• How to force ADF to speak your language (or any common language)

  - by Blueberry Coder

  When I started working for Oracle, one of the first tasks I was given was to contribute some content to a great ADF course Frank and Chris are building. Among other things, they asked me to work on a module about Internationalization. While doing research work, I unearthed a little gem I had overlooked all those years. JDeveloper, as you may know, speaks your language - as long as your language is English, that is. Oracle ADF, on the other hand, is a citizen of the world. It is available in more than 25 different languages. But while this is a wonderful feature for end users, it is rather cumbersome for developers. Why is that? Have you ever tried to search the OTN forums for a solution with a non-English error message as your query? I have, once. But how can you force ADF to use English for its logging operations? Playing with your system settings will not help, unfortunately. By default, ADF will output its error messages in the selected locale for the operating system account the application server runs on. The only way to change this behavior is to pass initialization parameters to the JVM used by the application server. It is even possible to specify the language and country/region separately. In the example below, we choose English and the United States respectively. -Duser.language=en -Duser.country=US In the case of WebLogic Server, it is possible to add such parameters in setDomainEnv.sh (or .cmd) to apply the settings to all the managed servers present on a node. In the coming weeks, I will write a few posts about other internationalization issues. Is there anything you would like me to cover? Let me know in the comments.

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• Oracle OpenWorld Recap - A Walk in the Clouds (and heat in San Francisco)!

  - by Di Seghposs

  Whether you were one of the 50,000 attendees in San Francisco or one of the million+ online attendees – we’d like to thank you for joining us at Oracle OpenWorld last week! With temperatures in the 80s and 90s, attendees traveled the overheated streets to join packed keynotes and general sessions – all to find the information they came in search of – Oracle solutions to address their business requirements and challenges. The buzz of this year’s OpenWorld was all about ‘The Cloud’. And, the financial management team joined in the cloud buzz with Thomas Kurian’s keynote which highlighted our ERP Cloud Service as the most complete cloud service on the market. Offering the full breadth of business operations, including Financial Management, Risk and Control Management, Project Portfolio Management, Procurement, Sourcing, and Inventory Management, Oracle ERP Cloud Service transforms the back office into a collaborative, efficient, and intuitive hub. And, our product marketing expert on Financial Management, Annette Melatti, provided a glimpse of what the office of finance looks like in the 21st century as well as shared what’s next for Oracle’s financial solutions discussing the future of Financial Management with Fusion Financials, E-Business Suite, PeopleSoft and the JD Edwards solutions. There were over 120 sessions from customers, partners, and Oracle experts that addressed financial management solutions along with demo pods and Meet the Experts sessions. We hope you found what you were looking for! Missed any of the keynotes or general sessions? Watch them on demand here. At OpenWorld, we also announced that Lending Club, the leading platform for investing in and obtaining personal loans, has selected Oracle ERP Cloud Service to help improve decision-making, implement robust reporting, and take advantage of the cost savings provided by the cloud. The CFO of Lending Club, Carrie Dolan had mentioned that they “are an innovative, data-intensive, high-growth company and needed a solution and partner that could match us. We conducted a thorough review of our options, and Oracle ERP Cloud Service was the clear winner in terms of capabilities and business value as well as commitment to us as a customer.” Read the entire release here. For now, it’s back to business as we gear up for the second half of our fiscal year and start planning for Oracle OpenWorld 2013!

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• Transformation?

  - by Joe G

  I started working at Oracle in 1997.  Since then, we (and most everyone) have been talking about transforming finance operations....but what does that mean exactly?  From my perspective, I thought it meant eliminate waste and menial tasks and giving your finance team more time to work on more strategic things.  That seems logical and simplistic, but how much progress have finance teams (and their IT departments) really made over the past fifteen years? I have yet to talk to a customer that doesn't have one amusing task that makes me chuckle.  Sometimes they still print hard copies of transactions to "file," or sometimes they print 700 pages of data to "analyze," or sometimes they cut and paste from one or more reports into a spreadsheet.  Upon hearing these things, my first question is always, "Why do you do that?" to which their response is rarely the same.    Sometimes it's related to trust (both the employee and the system).  Sometimes, it's habit-based.  And sometimes it is just impossible to accomplish the end result without some manual effort. I will say that I used to print nearly everything that I needed to review.  Partly, because I liked having the ability to scribble notes on the paper, and partly, because it was uncomfortable to read online.  However, I have changed. Rarely do I print anything anymore.  It's easier for me to read and notate online, and well, I guess I've just changed my habits. So where do you think our resistance to change comes from?  Is it truly deficits in our systems, or is it our own personal resistance to change?  What's your most annoying & untransformed task?

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• Why do VMs need to be "stack machines" or "register machines" etc.?

  - by Prog

  (This is an extremely newbie-ish question). I've been studying a little about Virtual Machines. Turns out a lot of them are designed very similarly to physical or theoretical computers. I read that the JVM for example, is a 'stack machine'. What that means (and correct me if I'm wrong) is that it stores all of it's 'temporary memory' on a stack, and makes operations on this stack for all of it's opcodes. For example, the source code 2 + 3 will be translated to bytecode similar to: push 2 push 3 add My question is this: JVMs are probably written using C/C++ and such. If so, why doesn't the JVM execute the following C code: 2 + 3..? I mean, why does it need a stack, or in other VMs 'registers' - like in a physical computer? The underlying physical CPU takes care of all of this. Why don't VM writers simply execute the interpreted bytecode with 'usual' instructions in the language the VM is programmed with? Why do VMs need to emulate hardware, when the actual hardware already does this for us? Again, very newbie-ish questions. Thanks for your help

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• Should I always encapsulate an internal data structure entirely?

  - by Prog

  Please consider this class: class ClassA{ private Thing[] things; // stores data // stuff omitted public Thing[] getThings(){ return things; } } This class exposes the array it uses to store data, to any client code interested. I did this in an app I'm working on. I had a ChordProgression class that stores a sequence of Chords (and does some other things). It had a Chord[] getChords() method that returned the array of chords. When the data structure had to change (from an array to an ArrayList), all client code broke. This made me think - maybe the following approach is better: class ClassA{ private Thing[] things; // stores data // stuff omitted public Thing[] getThing(int index){ return things[index]; } public int getDataSize(){ return things.length; } public void setThing(int index, Thing thing){ things[index] = thing; } } Instead of exposing the data structure itself, all of the operations offered by the data structure are now offered directly by the class enclosing it, using public methods that delegate to the data structure. When the data structure changes, only these methods have to change - but after they do, all client code still works. Note that collections more complex than arrays might require the enclosing class to implement even more than three methods just to access the internal data structure. Is this approach common? What do you think of this? What downsides does it have other? Is it reasonable to have the enclosing class implement at least three public methods just to delegate to the inner data structure?

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• Oracle Weblogic 12c for New Projects–Webcast November 7th 2013

  - by JuergenKress

  Fast-growing organizations need to stay agile in the face of changing customer, business or market requirements. Oracle WebLogic Server 12c is the industry's best application server platform that allows you to quickly develop and deploy reliable, secure, scalable and manageable enterprise Java EE applications. WebLogic Server Java EE applications are based on standardized, modular components. WebLogic Server provides a complete set of services for those modules and handles many details of application behavior automatically, without requiring programming. New project applications are created by Java programmers, Web designers, and application assemblers. Programmers and designers create modules that implement the business and presentation logic for the application. Application assemblers assemble the modules into applications that are ready to deploy on WebLogic Server. Build and run high-performance enterprise applications and services with Oracle WebLogic Server 12c, available in three editions to meet the needs of traditional and cloud IT environments. Join us, in this webcast, as we will show you how WebLogic Server 12c helps you building and deploying enterprise Java EE applications with support for new features for lowering cost of operations, improving performance, enhancing scalability. Agenda Oracle WebLogic Server Introduction Application Development on WebLogic Using Java EE Overview of the Application Deployment Process Monitoring Application Performance Q&A November 07th, 2013   9am UTC/11am EET REGISTER NOW WebLogic Partner Community For regular information become a member in the WebLogic Partner Community please visit: http://www.oracle.com/partners/goto/wls-emea ( OPN account required). If you need support with your account please contact the Oracle Partner Business Center. Blog Twitter LinkedIn Mix Forum Wiki Technorati Tags: education,WebLogic,WebLogic Community,Oracle,OPN,Jürgen Kress

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• OpenGL : sluggish performance in extracting texture from GPU

  - by Cyan

  I'm currently working on an algorithm which creates a texture within a render buffer. The operations are pretty complex, but for the GPU this is a simple task, done very quickly. The problem is that, after creating the texture, i would like to save it. This requires to extract it from GPU memory. For this operation, i'm using glGetTexImage(). It works, but the performance is sluggish. No, i mean even slower than that. For example, an 8MB texture (uncompressed) requires 3 seconds (yes, seconds) to be extracted. That's mind puzzling. I'm almost wondering if my graphic card is connected by a serial link... Well, anyway, i've looked around, and found some people complaining about the same, but no working solution so far. The most promising advise was to "extract data in the native format of the GPU". Which i've tried and tried, but failed so far. Edit : by moving the call to glGetTexImage() in a different place, the speed has been a bit improved for the most dramatic samples : looking again at the 8MB texture, it knows requires 500ms, instead of 3sec. It's better, but still much too slow. Smaller texture sizes were not affected by the change (typical timing remained into the 60-80ms range). Using glFinish() didn't help either. Note that, if i call glFinish() (without glGetTexImage), i'm getting a fixed 16ms result, whatever the texture size or complexity. It really looks like the timing for a frame at 60fps. The timing is measured for the full rendering + saving sequence. The call to glGetTexImage() alone does not really matter. That being said, it is this call which changes the performance. And yes, of course, as stated at the beginning, the texture is "created into the GPU", hence the need to save it.

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• ubuntu boots only with usb

  - by klimat

  Just installed Ubuntu 11.04. But it boots only from usb. Seems like I didn't pay attention during selecting boot device. sudo fdisk -l [sudo] password for klim: Disk /dev/sda: 500.1 GB, 500107862016 bytes 255 heads, 63 sectors/track, 60801 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 bytes Disk identifier: 0x000177e1 Device Boot Start End Blocks Id System /dev/sda1 1 60045 482302976 83 Linux /dev/sda2 60045 60802 6080513 5 Extended Partition 2 does not start on physical sector boundary. /dev/sda5 60045 60802 6080512 82 Linux swap / Solaris Disk /dev/sdb: 4004 MB, 4004511744 bytes 124 heads, 62 sectors/track, 1017 cylinders Units = cylinders of 7688 * 512 = 3936256 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x000eee1a Device Boot Start End Blocks Id System /dev/sdb1 * 1 1017 3909317 b W95 FAT32 grub updating or another "grub" operations don't work as I've tried. Can I just copy whole boot folder from usb to HD or smth like that? Any kind of help is appreciated. Apologize for my newbie skills.

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• Could a singleton type replace static methods and classes?

  - by MKO

  In C# Static methods has long served a purpose allowing us to call them without instantiating classes. Only in later year have we became more aware of the problems of using static methods and classes. They can’t use interfaces They can’t use inheritance They are hard to test because you can’t make mocks and stubs Is there a better way ? Obviously we need to be able to access library methods without instantiated classes all the time otherwise our code would become pretty cluttered One possibly solution is to use a new keyword for an old concept: the singleton. Singleton’s are global instances of a class, since they are instances we can use them as we would normal classes. In order to make their use nice and practical we'd need some syntactic sugar however Say that the Math class would be of type singleton instead of an actual class. The actual class containing all the default methods for the Math singleton is DefaultMath, which implements the interface IMath. The singleton would be declared as singleton Math : IMath { public Math { this = new DefaultMath(); } } If we wanted to substitute our own class for all math operations we could make a new class MyMath that inherits DefaultMath, or we could just inherit from the interface IMath and create a whole new Class. To make our class the active Math class, you'd do a simple assignment Math = new MyMath(); and voilá! the next time we call Math.Floor it will call your method. Note that for a normal singleton we'd have to write something like Math.Instance.Floor but the compiler eliminates the need for the Instance property Another idea would be to be able to define a singletons as Lazy so they get instantiated only when they're first called, like lazy singleton Math : IMath What do you think, would it have been a better solution that static methods and classes? Is there any problems with this approach?

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• True column-mode (block-selection and editing) text editor solution?

  - by tamale

  In windows, I used to use a text editor called crimson editor which featured the best column-mode editing support I have yet to use. When enabled via a simple Alt-C shortcut, selections could be made with the mouse or cursor keys and they would be visual blocks rather than wrapped-lines. These selections could be deleted, moved, copied, pasted, and all of the operations just made sense. You could also just start typing, and you'd get a column of the characters as you're typing. There are multiple ways of getting parts of the these features working separately discussed on this forum thread, but no one has yet to provide a solution that provides this all-encompassing and easy-to-use method. If someone could point me to a gedit plugin where this work is actively being pursued, perhaps I could help with the coding myself. If someone is aware of a text editor that already provides this full functionality, I'd appreciate the info. Running crimson editor through wine and the close-but-not-quite multi-edit plugin for gedit are the temporary solutions I'm 'getting by with' for the time being.

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• Integer type or not [closed]

  - by kira

  I am writing a program (in cpp) to check the primality of a given number The point where i am struck is , I need to check in between the program wether the value i obtained upon some arithmetic operations on the input is an integer or not i.e lets say input is 'a' I want to know how to check if 'b' is integer or not (FYI, b=(a+1)/6 ) My attempt for this : int main() { using std::cin; using std::cout; int b,c; int a; cout<<"enter the number"; cin>>a; b=(a+1)/6; c=(a-1)/6; if (b is an integer) cout << "The given number is prime"; else if (c is an integer) cin << "The given number is prime!"; else cout<<"The number is not prime"; return 0; }

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• ubuntu 12.04 will not play DVDs

  - by ayelet

  First off, I'm not just a newbie, I'm clueless! So your answers will need to be in complete idiot language (let's say I'm computer saavy, and I can follow directions,but I've never programmed anything and assume I don't understand any abbreviations. So why am I running linux? b/c windows was driving me nuts!! and my friend convinced me. day-to-day operations, we're doing fine, but when it comes to problems, I've got no clue what I'm doing!) So here's what's going on, my machine is an HP pavilion dv6, my optical drive is a standard cd/dvdrw, when i load an audio cd of any type (burned, official, etc,..) I have no problems, when I pop in a dvd - i get nothing. the dvd icon comes up in my launch tray, when I open VLC player I can find the dvd in the folder... but it won't play. I can watch movies I've downloaded with no problem, I can also watch movies off an external hard drive. The only thing I've tried is removing vlc and reinstalling, and I tried installing a different player (gnome maybe? I don't remember). none of that worked. Again, i can follow directions, but you need to be very specific and don't assume I know anything going in. (I mean, I know basic stuff, but nothing too technical.) PLEASE HELP!!! MY KIDS ARE DRIVING ME CRAZY!!! Thanks!!

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• Using the Coherence ConcurrentMap Interface (Locking API)

  - by jpurdy

  For many developers using Coherence, the first place they look for concurrency control is the com.tangosol.util.ConcurrentMap interface (part of the NamedCache interface). The ConcurrentMap interface includes methods for explicitly locking data. Despite the obvious appeal of a lock-based API, these methods should generally be avoided for a variety of reasons: They are very "chatty" in that they can't be bundled with other operations (such as get and put) and there are no collection-based versions of them. Locks do directly not impact mutating calls (including puts and entry processors), so all code must make explicit lock requests before modifying (or in some cases reading) cache entries. They require coordination of all code that may mutate the objects, including the need to lock at the same level of granularity (there is no built-in lock hierarchy and thus no concept of lock escalation). Even if all code is properly coordinated (or there's only one piece of code), failure during updates that may leave a collection of changes to a set of objects in a partially committed state. There is no concept of a read-only lock. In general, use of locking is highly discouraged for most applications. Instead, the use of entry processors provides a far more efficient approach, at the cost of some additional complexity.

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