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• Are these advanced/unfair interview questions regarding Java concurrency?

  - by sparc_spread

  Here are some questions I've recently asked interviewees who say they know Java concurrency: Explain the hazard of "memory visibility" - the way the JVM can reorder certain operations on variables that are unprotected by a monitor and not declared volatile, such that one thread may not see the changes made by another thread. Usually I ask this one by showing code where this hazard is present (e.g. the NoVisibility example in Listing 3.1 from "Java Concurrency in Practice" by Goetz et al) and asking what is wrong. Explain how volatile affects not just the actual variable declared volatile, but also any changes to variables made by a thread before it changes the volatile variable. Why might you use volatile instead of synchronized? Implement a condition variable with wait() and notifyAll(). Explain why you should use notifyAll(). Explain why the condition variable should be tested with a while loop. My question is - are these appropriate or too advanced to ask someone who says they know Java concurrency? And while we're at it, do you think that someone working in Java concurrency should be expected to have an above-average knowledge of Java garbage collection?

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• Ubuntu 13.10 Unity doesn't load after upgrade

  - by William

  Just upgraded to Ubuntu 13.10 only to find that Unity won't load (login freezes, after doing ctrl+alt+F1, logging in and then doing startx, I get a blank desktop and the mouse pointer, and nothing else). I can right click, but the only operations that work are "create new file" and "create new folder". For example, "change desktop background" doesn't work. Also, after doing a few right clicks and choosing "change desktop background", I get a warning message box: "compiz closed unexpectedly." Guest login works fine. Tried creating a new user, but I experience the same thing with the new user. Tried removing all configuration files from my home directory... same thing. Doing dconf reset -f /org/compiz/ gives an error "error spawning command line..." Doing unity --reset also gives errors. Tried uninstalling unity (and compiz) and reinstalling, but that doesn't help. Tried reconfiguring lightdm, didn't help. I don't have any proprietary drivers installed. Once again, the funny thing is that the guest session works fine.

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• Partner Webcast – Oracle Weblogic 12c for New Projects - 07 Nov 2013

  - by Thanos Terentes Printzios

  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 deployingenterprise 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 Delivery FormatThis FREE online LIVE eSeminar will be delivered over the Web. Registrations received less than 24hours prior to start time may not receive confirmation to attend. Duration: 1 hour REGISTER NOW For any questions please contact us at partner.imc-AT-beehiveonline.oracle-DOT-com Stay Connected Oracle Newsletters

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• Does LINQ require significantly more processing cycles and memory than lower-level data iteration techniques?

  - by Matthew Patrick Cashatt

  Background I am recently in the process of enduring grueling tech interviews for positions that use the .NET stack, some of which include silly questions like this one, and some questions that are more valid. I recently came across an issue that may be valid but I want to check with the community here to be sure. When asked by an interviewer how I would count the frequency of words in a text document and rank the results, I answered that I would Use a stream object put the text file in memory as a string. Split the string into an array on spaces while ignoring punctuation. Use LINQ against the array to .GroupBy() and .Count(), then OrderBy() said count. I got this answer wrong for two reasons: Streaming an entire text file into memory could be disasterous. What if it was an entire encyclopedia? Instead I should stream one block at a time and begin building a hash table. LINQ is too expensive and requires too many processing cycles. I should have built a hash table instead and, for each iteration, only added a word to the hash table if it didn't otherwise exist and then increment it's count. The first reason seems, well, reasonable. But the second gives me more pause. I thought that one of the selling points of LINQ is that it simply abstracts away lower-level operations like hash tables but that, under the veil, it is still the same implementation. Question Aside from a few additional processing cycles to call any abstracted methods, does LINQ require significantly more processing cycles to accomplish a given data iteration task than a lower-level task (such as building a hash table) would?

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• Debugger for file I/O development?

  - by datenwolf

  Okay, the question title may be a bit cryptic. But it aptly describes what I'm looking for: I think every experienced coder went through this numerous times: You get a binary file format specification, you implement the reader for it, and… nothing works like expected. So you run your code in the debugger, go execute through the code line by line, every header field is read in seemingly correct, but when it comes to the bulk data, offset and indices no longer match up. What would really help in this situation was a binary file viewer, that shows you the progress of your file pointer, as you step through the code, and ideally would also highlight all memory maps. Then you could see the context of the current I/O operations, most notably those darn "off-by-one" mistakes, which are even more annoying when reading a file. Implementing such a debugger should not be too hard. traces on the process' file descriptors/handles and triggers on the I/O functions, to update the display. Only: I don't know of such a kind of debugger to exist. Do I just lack knowledge about the existance of such a tool, or is there really no such thing?

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• Is ZeroMQ a good choice to make a Python app and a C# managed assembly work together?

  - by Alex Bausk

  I have a task that involves talking to a .NET-based API (namely AutoCAD) to retrieve data, send commands, and react to events. I want to separate the API operations and the proper program logic (largely already implemented in Python) by using natural tools for both: a C# DLL for the former and a Python app for the latter. To connect these two pieces, I began exchanging JSON in ZeroMQ messages. I'm at early development stages but having recently discovered that ZeroMQ does not guarantee message delivery/order, I have reservations about whether this is a feasible way to go. Right now my app is a very basic REQ/REP pair and I plan to handle reacting to events and executing different commands by adding some sort of 'recipient-function' field to my message format. The reason that I want to use ZMQ is that I might be able to scale the software into a larger, multi-user, distributed solution sometime. I am a lay programmer so I would ask for your advice about this architecture. Should I just go ahead with it and plan to deal with message reliability/ordering when problems appear? Should I consider developing some kind of a REST wrapper around ZMQ?

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• How to handle monetary values in PHP and MySql?

  - by Songo

  I've inherited a huge pile of legacy code written in PHP on top of a MySQL database. The thing I noticed is that the application uses doubles for storage and manipulation of data. Now I came across of numerous posts mentioning how double are not suited for monetary operations because of the rounding errors. However, I have yet to come across a complete solution to how monetary values should be handled in PHP code and stored in a MySQL database. Is there a best practice when it comes to handling money specifically in PHP? Things I'm looking for are: How should the data be stored in the database? column type? size? How should the data be handling in normal addition, subtraction. multiplication or division? When should I round the values? How much rounding is acceptable if any? Is there a difference between handling large monetary values and low ones? Note: A VERY simplified sample code of how I might encounter money values in everyday life: $a= $_POST['price_in_dollars']; //-->(ex: 25.06) will be read as a string should it be cast to double? $b= $_POST['discount_rate'];//-->(ex: 0.35) value will always be less than 1 $valueToBeStored= $a * $b; //--> any hint here is welcomed $valueFromDatabase= $row['price']; //--> price column in database could be double, decimal,...etc. $priceToPrint=$valueFromDatabase * 0.25; //again cast needed or not? I hope you use this sample code as a means to bring out more use cases and not to take it literally of course. Bonus Question If I'm to use an ORM such as Doctrine or PROPEL, how different will it be to use money in my code.

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• Beginners guide to developing optimization software

  - by Florenc

  I am novice in "serious" programming i.e. applications that deal with real-life applications and software projects that go beyond school assignments. My interests include optimization, operations research, algorithms and lately i discovered how much I do like software design/development/engineering. I have already developed some simple desktop applications for some "famous" problems like TSP using heuristc approaches, a VRP solver (in progress) and so on. While developing this kind of software I actually used basic concepts taught at school such as object-orientation analysis and design. But, I found these courses rather elementary and quite boring (for my expectations). So I decided to go a little further and start developing "real" software (and this is where I realized how important and interesting software engineering/design is.) Now, here's my issue: I can not find a "study guide" for developing software of this kind. Currently, there are numerous resources out there (books, websites, tutorials) in designing and developing complex IS, web applications, smartphone apps but I can't find a book for example entitled "optimization software development". Definetly, someone could claim that "design patterns apply to software in general" but that's not my point. My point is that I could simply use my imagination for "simple" implementations, but what happens, when my imagination can not go further? In other words I'm looking for a guide/path to bridge the gap between: Mathematics-Algorithm Design-Software Engineering-Optimization-Software development

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• Mercurial says "nothing changed", but it did. Sometimes my software is too clever.

  - by user12608033

  It seems I have found a "bug" in Mercurial. It takes a shortcut when checking for differences in tracked files. If the file's size and modification time are unchanged, it assumes its contents are unchanged: $ hg init . $ cp -p .sccs2hg/2005-06-05_00\:00\:00\,nicstat.c nicstat.c $ ls -ogE nicstat.c -rw-r--r-- 1 14722 2012-08-24 11:22:48.819451726 -0700 nicstat.c $ hg add nicstat.c $ hg commit -m "added nicstat.c" $ cp -p .sccs2hg/2005-07-02_00\:00\:00\,nicstat.c nicstat.c $ ls -ogE nicstat.c -rw-r--r-- 1 14722 2012-08-24 11:22:48.819451726 -0700 nicstat.c $ hg diff $ hg commit nothing changed $ touch nicstat.c $ hg diff diff -r b49cf59d431d nicstat.c --- a/nicstat.c Fri Aug 24 11:21:27 2012 -0700 +++ b/nicstat.c Fri Aug 24 11:22:50 2012 -0700 @@ -2,7 +2,7 @@ * nicstat - print network traffic, Kb/s read and written. Solaris 8+. * "netstat -i" only gives a packet count, this program gives Kbytes. * - * 05-Jun-2005, ver 0.81 (check for new versions, http://www.brendangregg.com) + * 02-Jul-2005, ver 0.90 (check for new versions, http://www.brendangregg.com) * [...] Now, before you agree or disagree with me on whether this is a bug, I will also say that I believe it is a feature. Yes, I feel it is an acceptable shortcut because in "real" situations an edit to a file will change the modification time by at least one second (the resolution that hg diff or hg commit is looking for). The benefit of the shortcut is greatly improved performance of operations like "hg diff" and "hg status", particularly where your repository contains a lot of files. Why did I have no change in modification time? Well, my source file was generated by a script that I have written to convert SCCS change history to Mercurial commits. If my script can generate two revisions of a file within a second, and the files are the same size, then I run afoul of this shortcut. Solution - I will just change my script to apply the modification time from the SCCS history to the file prior to commit. A "touch -t " will do that easily.

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• TXPAUSE : polite waiting for hardware transactional memory

  - by Dave

  Classic locks are an appropriate tool to prevent potentially conflicting operations A and B, invoked by different threads, from running at the same time. In a sense the locks cause either A to run before B or vice-versa. Similarly, we can replace the locks with hardware transactional memory, or use transactional lock elision to leverage potential disjoint access parallelism between A and B. But often we want A to wait until B has run. In a Pthreads environment we'd usually use locks in conjunction with condition variables to implement our "wait until" constraint. MONITOR-MWAIT is another way to wait for a memory location to change, but it only allows us to track one cache line and it's only available on x86. There's no similar "wait until" construct for hardware transactions. At the instruction-set level a simple way to express "wait until" in transactions would be to add a new TXPAUSE instruction that could be used within an active hardware transaction. TXPAUSE would politely stall the invoking thread, possibly surrendering or yielding compute resources, while at the same time continuing to track the transaction's address-set. Once a transaction has executed TXPAUSE it can only abort. Ideally that'd happen when some other thread modifies a variable that's in the transaction's read-set or write-set. And since we're aborting all writes would be discarded. In a sense this gives us multi-location MWAIT but with much more flexibility. We could also augment the TXPAUSE with a cycle-count bound to cap the time spent stalled. I should note that we can already enter a tight spin loop in a transaction to wait for updates to address-set to cause an abort. Assuming that the implementation monitors the address-set via cache-coherence probes, by waiting in this fashion we actually communicate via the probes, and not via memory values. That is the updating thread signals the waiter via probes instead of by traditional memory values. But TXPAUSE gives us a polite way to spin.

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• Name of the Countdown Numbers round problem - and algorithmic solutions?

  - by Dai

  For the non-Brits in the audience, there's a segment of a daytime game-show where contestants have a set of 6 numbers and a randomly generated target number. They have to reach the target number using any (but not necessarily all) of the 6 numbers using only arithmetic operators. All calculations must result in positive integers. An example: Youtube: Countdown - The Most Extraordinary Numbers Game Ever? A detailed description is given on Wikipedia: Countdown (Game Show) For example: The contentant selects 6 numbers - two large (possibilities include 25, 50, 75, 100) and four small (numbers 1 .. 10, each included twice in the pool). The numbers picked are 75, 50, 2, 3, 8, 7 are given with a target number of 812. One attempt is (75 + 50 - 8) * 7 - (3 * 2) = 813 (This scores 7 points for a solution within 5 of the target) An exact answer would be (50 + 8) * 7 * 2 = 812 (This would have scored 10 points exactly matching the target). Obviously this problem has existed before the advent of TV, but the Wikipedia article doesn't give it a name. I've also saw this game at a primary school I attended where the game was called "Crypto" as an inter-class competition - but searching for it now reveals nothing. I took part in it a few times and my dad wrote an Excel spreadsheet that attempted to brute-force the problem, I don't remember how it worked (only that it didn't work, what with Excel's 65535 row limit), but surely there must be an algorithmic solution for the problem. Maybe there's a solution that works the way human cognition does (e.g. in-parallel to find numbers 'close enough', then taking candidates and performing 'smaller' operations).

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• Data Synchronization in mobile apps - multiple devices, multiple users

  - by ProgrammerNewbie

  I'm looking into building my first mobile app. One of the core features of the application is that multiple devices/users will have access to the same data -- and all of them will have CRUD rights. I believe the architecture should involve a central server where all the data is stored. The devices will use an API to interact with the server to perform its data operations (e.g. adding a record, editing a record, deleting a record). I imagine a scenario where synchronizing the data will become a problem. Assume the application should work when it is not connected to the Internet, and thus cannot communicate with this central server. So: User A is offline and edits record #100 User B is offline and edits record #100 User C is offline and deletes record #100 User C goes online (presumably, record #100 should get deleted on the server) User A and B goes online, but the records they edited no longer exist All sorts of scenarios similar to the above can come up. How is this generally handled? I plan to use MySQL, but am wondering if it's not appropriate for such a problem.

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• String manipulation functions in SQL Server 2000 / 2005

  - by Vipin

  SQL Server provides a range of string manipulation functions. I was aware of most of those in back of the mind, but when I needed to use one, I had to dig it out either from SQL server help file or from google. So, I thought I will list some of the functions which performs some common operations in SQL server. Hope it will be helpful to you all. Len (' String_Expression' ) - returns the length of input String_Expression. Example - Select Len('Vipin') Output - 5 Left ( 'String_Expression', int_characters ) - returns int_characters characters from the left of the String_Expression.     Example - Select Left('Vipin',3), Right('Vipin',3) Output -  Vip,  Pin  LTrim ( 'String_Expression' ) - removes spaces from left of the input 'String_Expression'  RTrim ( 'String_Expression' ) - removes spaces from right of the input 'String_Expression' Note - To removes spaces from both ends of the string_expression use Ltrim and RTrim in conjunction Example - Select LTrim(' Vipin '), RTrim(' Vipin ') , LTrim ( RTrim(' Vipin ')) Output - 'Vipin ' , ' Vipin' , 'Vipin' (Single quote marks ' ' are not part of the SQL output, it's just been included to demonstrate the presence of space at the end of string.) Substring ( 'String_Expression' , int_start , int_length ) - this function returns the part of string_expression. Right ( 'String_Expression', int_characters ) - returns int_characters characters from the right of the String_Expression.

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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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• Why is apt-cache so slow?

  - by Damn Terminal

  After upgrade to Trusty (14.04) from Saucy (13.10), all apt operations are very slow. Even those that do not include downloading anything, or connecting to any servers. For example, displaying the apt policy # time apt-cache policy [...] real 0m8.951s user 0m5.069s sys 0m3.861s takes almost ten seconds! Mostly a weird lag right after issuing the command. And it's the same even if I issue the same command again. On another system it doesn't take a tenth of a second real 0m0.096s user 0m0.070s sys 0m0.023s The other system is a little beefier but there was no noticeable difference before the upgrade. It's the same with apt-get, anything apt-related. How do I find out the source of this lag and fix it? Additional info: # cat /etc/nsswitch.conf # /etc/nsswitch.conf # # Example configuration of GNU Name Service Switch functionality. # If you have the `glibc-doc-reference' and `info' packages installed, try: # `info libc "Name Service Switch"' for information about this file. passwd: compat group: compat shadow: compat hosts: files dns networks: files protocols: db files services: db files ethers: db files rpc: db files netgroup: nis BTW is my understanding of how apt-cache works correct? It doesn't make any network connections when I run apt-cache policy, right? In case I'm wrong and it matters, here are my sources https://gist.github.com/anonymous/02920270ff68e23fc3ec

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• Using visitor pattern with large object hierarchy

  - by T. Fabre

  Context I've been using with a hierarchy of objects (an expression tree) a "pseudo" visitor pattern (pseudo, as in it does not use double dispatch) : public interface MyInterface { void Accept(SomeClass operationClass); } public class MyImpl : MyInterface { public void Accept(SomeClass operationClass) { operationClass.DoSomething(); operationClass.DoSomethingElse(); // ... and so on ... } } This design was, however questionnable, pretty comfortable since the number of implementations of MyInterface is significant (~50 or more) and I didn't need to add extra operations. Each implementation is unique (it's a different expression or operator), and some are composites (ie, operator nodes that will contain other operator/leaf nodes). Traversal is currently performed by calling the Accept operation on the root node of the tree, which in turns calls Accept on each of its child nodes, which in turn... and so on... But the time has come where I need to add a new operation, such as pretty printing : public class MyImpl : MyInterface { // Property does not come from MyInterface public string SomeProperty { get; set; } public void Accept(SomeClass operationClass) { operationClass.DoSomething(); operationClass.DoSomethingElse(); // ... and so on ... } public void Accept(SomePrettyPrinter printer) { printer.PrettyPrint(this.SomeProperty); } } I basically see two options : Keep the same design, adding a new method for my operation to each derived class, at the expense of maintainibility (not an option, IMHO) Use the "true" Visitor pattern, at the expense of extensibility (not an option, as I expect to have more implementations coming along the way...), with about 50+ overloads of the Visit method, each one matching a specific implementation ? Question Would you recommand using the Visitor pattern ? Is there any other pattern that could help solve this issue ?

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• Live Webcast: Discover Primavera Unifier - December 5th

  - by Melissa Centurio Lopes

  Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Join our live webcast to see what Primavera Unifier can do for you and your organization. We are very excited to introduce you to the newest addition to the Primavera product family, Primavera Unifier (formerly known as Skire Unifier). Attend this webcast and learn why this new cloud-based solution is the most comprehensive Enterprise Project Portfolio Management (EPPM) offering to manage the complete project lifecycle, from capital planning and construction to operations and maintenance. Save your seat: Register today for this online event and learn how the addition of Primavera Unifier can help your organization manage their projects and facilities with more predictability and financial control, improving profitability and operational efficiency

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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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• Anemic Domain Model, Business Logic and DataMapper (PHP)

  - by sunwukung

  I've implemented a rudimentary ORM layer based on DataMapper (I don't want to use a full blown ORM like Propel/Doctrine - for anything beyond simple fetch/save ops I prefer to access the data directly layer using a SQL abstraction layer). Following the DataMapper pattern, I've endeavoured to keep all persistence operations in the Mapper - including the location of related entities. My Entities have access to their Mapper, although I try not to call Mapper logic from the Entity interface (although this would be simple enough). The result is: // get a mapper and produce an entity $ProductMapper = $di->get('product_mapper'); $Product = $ProductMapper->find('[email protected]','email'); //.. mutaute some values.. save $ProductMapper->save($Product) // uses __get to trigger relation acquisition $Manufacturer = $Product->manufacturer; I've read some articles regarding the concept of an Anemic Domain model, i.e. a Model that does not contain any "business logic". When demonstrating the sort of business logic ideally suited to a Domain Model, however, acquiring related data items is a common example. Therefore I wanted to ask this question: Is persistence logic appropriate in Domain Model objects?

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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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• Oracle Solaris 11.1 available today

  - by user12611852

  Today Oracle is pleased to announce availability of Oracle Solaris 11.1. Download Solaris 11.1 Order Solaris 11.1 media kitExisting customers can quickly and simply update using the network based repository Highlights include: 8x faster database startup and shutdown and online resizing of the database SGA with a new optimized shared memory interface between the database and Oracle Solaris 11.1 Up to 20% throughput increases for Oracle Real Application Clusters by offloading lock management into the Oracle Solaris kernel Expanded support for Software Defined Networks (SDN) with Edge Virtual Bridging enhancements to maximize network resource utilization and manage bandwidth in cloud environments 4x faster Solaris Zone updates with parallel operations shorten maintenance windows New built-in memory predictor monitors application memory use and provides optimized memory page sizes and resource location to speed overall application performance. Learn more and share these valuable tools with your customers to enable them to move to Oracle Solaris 11.1 quickly. Many customers wait for the first update --now is the time to encourage them to install Oracle Solaris 11.1. Oracle Solaris 11.1 Data Sheet  What's New in Oracle Solaris 11.1 Oracle Solaris 11.1 FAQs Oracle Solaris 11 .1 Customer Presentation Oracle Solaris 11.1 is recommended for all SPARC T4 Systems and will soon be available preinstalled.

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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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• 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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• [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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