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  • Is Akka a good solution for a concurrent pipeline/workflow problem?

    - by herpylderp
    Disclaimer: I am brand new to Akka and the concept of Actors/Event-Driven Architectures in general. I have to implement a fairly complex problem where users can configure a "concurrent pipeline": Pipeline: consists of 1+ Stages; all Stages execute sequentially Stage: consists of 1+ Tasks; all Tasks execute in parallel Task: essentially a Java Runnable As you can see above, a Task is a Runnable that does some unit of work. Tasks are organized into Stages, which execute their Tasks in parallel. Stages are organized into the Pipeline, which executes its Stages sequentially. Hence if a user specifies the following Pipeline: CrossTheRoadSafelyPipeline Stage 1: Look Left Task 1: Turn your head to the left and look for cars Task 2: Listen for cars Stage 2: Look right Task 1: Turn your head to the right and look for cars Task 2: Listen for cars Then, Stage 1 will execute, and then Stage 2 will execute. However, while each Stage is executing, it's individual Tasks are executing in parallel/at the same time. In reality Pipelines will become very complicated, and with hundreds of Stages, dozens of Tasks per Stage (again, executing at the same time). To implement this Pipeline I can only think of several solutions: ESB/Apache Camel Guava Event Bus Java 5 Concurrency Actors/Akka Camel doesn't seem right because its core competency is integration not synchrony and orchestration across worker threads. Guava is great, but this doesn't really feel like a subscriber/publisher-type of problem. And Java 5 Concurrency (ExecutorService, etc.) just feels too low-level and painful. So I ask: is Akka a strong candidate for this type of problem? If so, how? If not, then why, and what is a good candidate?

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  • Two interesting big data sessions around Openworld

    - by Jean-Pierre Dijcks
    For those who want to talk (not listen) about big data, here are 2 very cool sessions: BOF9877 - A birds of a feather session around all things big data. It is on Monday, Oct 1, 6:15 PM - 7:00 PM - Marriott Marquis - Golden Gate. While all guests on the panel are special, we will have very special guest on the panel. He is a proud owner of a Big Data Appliance (see here). Then there is a Big Data SIG meeting (the invite from Gwen): I'd like to invite everyone to our OOW12 meet up. We'll meet on Tuesday, October 2nd, 8:45 to 9:45 at Moscone West Level 3, Overlook 3. We will network, socialize and discuss plans for the group. Which topics interest us for webinars? Which conferences do we want to meet in? What other activities we are interested in? We can also discuss big data topics, show off our great work, and seek advice on the challenges. Other than figuring out what we are collectively interested in, the discussion will be pretty open. Here is the official invite. See you at Openworld!!

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  • How to justify rewriting/revamping legacy software in a business case?

    - by sxthomson
    I work for a great little software company which makes good revenue from our main software package. The problem for me is that it's almost unmaintainable. It's written in Delphi 7 (has upgraded versions over time) and has been worked on by a lot of developers over the past 20 or so years. The software lacks any meaningful architecture - there's no object orientation whatsoever, horrible amounts of cyclical dependencies and an over-reliance on global variables to name just a few things. Another huge thing for me is Delphi 7 does NOT support 64-bit. The problem here for me is that my management team don't care about technical things, they want to know why they should care. Obviously that's expected, so what I'm asking here is for some guidance, or tales, or pitfalls about this kind of thing. There's a few things I would love to include, namely for me, the length of time taken to debug/write a feature in "legacy" code, versus coherent, well structured OO code. Does anyone know of any blog posts or the like where this is talked about? For us in the company this is a huge reason. Despite being decent developers we feel like writing a new feature is just piling more rubbish on top. On top of that, even for me who has a decent level of understanding of the code, changing things is infuriating - a small change can have a ridiculous domino effect. Anyone have any experiences they'd like to share?

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  • Windows Physical Direct Memory Mapping

    - by chrisjleaf
    I'm a bit disappointed there is almost no discussion of this no matter where I look so I guess I'll have to ask. I'm writing a cross platform memory bench marking application which requires direct physical address mapping rather than virtual addressing. EDIT The solution would look something like the Linux/Unix system calls: int fd = open("/dev/mem", O_RDONLY); mmap(NULL, len, PROT_READ, MAP_SHARED, fd, PHYSICAL_ADDRESS_OFFSET); which will require the kernel to either give you a virtual page mapping to the desired physical address or return that it failed. This does require supervisor privileges but that is ok. I have seen a lot of information about shared memory and memory mapped files but all of these reside on disc and are thus not really useful when I'm trying to make a system dependent read. It is very similar to writing an IO driver although I do no need write permissions to the physical address. This site gives an example of how to do it on a driver level using the Windows Driver Kit: NT Insider: Sharing Memory between drivers and applications This solution would probably require Visual Studio which currently I do not have access to. (I have downloaded the WDK api but it complained about my use of GCC for Windows). I'm traditionally a Linux programmer so I'm hoping there might be something really simple I'm missing. Thanks in advance if you know something I don't!

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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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  • New Write Flash SSDs and more disk trays

    - by Steve Tunstall
    In case you haven't heard, the Write SSDs the ZFSSA have been updated. Much faster now for the same price. Sweet. The new write-flash SSDs have a new part number of 7105026 , so make sure you order the right ones. It's important to note that you MUST be on code level 2011.1.4.0 or higher to use these. They have increased in IOPS from 6,000 to 11,000, and increased throughput from 200MB/s to 350MB/s.    Also, you can now add six SAS HBAs (up from 4) to the 7420, allowing one to have three SAS channels with 12 disk trays each, for a new total of 36 disk trays. With 3TB drives, that's 2.5 Petabytes. Is that enough for you? Make sure you add new cards to the correct slots. I've talked about this before, but here is the handy-dandy matrix again so you don't have to go find it. Remember the rules: You can have 6 of any one kind of card (like six 10GigE cards), but you only really get 8 slots, since you have two SAS cards no matter what. If you want more than 12 disk trays, you need two more SAS cards, so think about expansion later, too. In fact, if you are going to have two different speeds of drives, in other words you want to mix 15K speed and 7,200 speed drives in the same system, I would highly recommend two different SAS channels. So I would want four SAS cards in that system, no matter how many trays you have. 

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  • Start building websites using Java

    - by Alex coady
    I'm a web developer and I've used PHP, along with MySQL, Javascript, jQuery etc; all of which I'm very confident with and can use on a professional level. What I'm wanting to do however, is to start using Java instead of PHP as I'm creating sites that need to be scalable. I really need a starting point. I can program in Java, I understand the language but have never used it for the web. Links, tutorials, examples would be a great help. I have also considered using Scala (the language Twitter is written in).. but don't really understand the benefits. Please no jargon; I need clear information that essentially takes me through the process of creating a very simple website using Java; I'm more than capable of building the site once that's done.. I think. I've previously used Eclipse so if assume I can. Thanks in advance!

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  • C# class architecture for REST services

    - by user15370
    Hi. I am integrating with a set of REST services exposed by our partner. The unit of integration is at the project level meaning that for each project created on our partners side of the fence they will expose a unique set of REST services. To be more clear, assume there are two projects - project1 and project2. The REST services available to access the project data would then be: /project1/search/getstuff?etc... /project1/analysis/getstuff?etc... /project1/cluster/getstuff?etc... /project2/search/getstuff?etc... /project2/analysis/getstuff?etc... /project2/cluster/getstuff?etc... My task is to wrap these services in a C# class to be used by our app developer. I want to make it simple for the app developer and am thinking of providing something like the following class. class ProjectClient { SearchClient _searchclient; AnalysisClient _analysisclient; ClusterClient _clusterclient; string Project {get; set;} ProjectClient(string _project) { Project = _project; } } SearchClient, AnalysisClient and ClusterClient are my classes to support the respective services shown above. The problem with this approach is that ProjectClient will need to provide public methods for each of the API's exposed by SearchClient, etc... public void SearchGetStuff() { _searchclient.getStuff(); } Any suggestions how I can architect this better?

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  • Software Manager who makes developers do Project Management

    - by hdman
    I'm a software developer working in an embedded systems company. We have a Project Manager, who takes care of the overall project schedule (including electrical, quality, software and manufacturing) hence his software schedule is very brief. We also have a Software Manager, who's my boss. He makes me write and maintain the software schedule, design documents (high and low level design), SRS, change management, verification plans and reports, release management, reviews, and ofcourse the software. We only have one Test Engineer for the whole software team (10 members), and at any given time, there are a couple of projects going on. I'm spending 80% of my time making these documents. My boss comes from a Process background, and believes what we need is better documentation to improve software: (1) He considers the design to be paramount, coding is "just writing the design down", it shouldn't take too long, and "all the code should be written before the hardware is ready". (2) Doesn't understand the difference between a Central & Distributed Version control, even after we told him its easier to collaborate with a distributed model. (3) Doesn't understand code, and wants to understand every bug and its proposed solution. (4) Believes verification should be done by developer, and validation by the Tester. Thing is though, our verification only checks if implementation is correct (we don't write unit tests, its never considered in the schedule), and validation is black box testing, so the units tests are missing. I'm really confused. (1) Am I responsible for maintaining all these documents? It makes me feel like I'm doing the Software Project Management, in essence. (2) I don't really like creating documents, I want to solve problems and write code. In my experience, creating design documents only helps to an extent, its never the solution to better or faster code. (3) I feel the boss doesn't really care about making better products, but only about being a good manager in the eyes of the management. What can I do?

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  • The latest version of the EJB 3.2 spec available on java.net project

    - by Marina Vatkina
    If you are not following us on the users alias, here is a quick update. Just before JavaOne, I uploaded the latest version of the EJB 3.2 Core document to the ejb-spec.java.net downloads. If you want to see the detailed changes, download it If you are interested in the high-level list, or would like to know what to look for, this is the list of changes since the previous version (found on the same download page): Specified that the SessionContext object in a the singleton session bean is thread-safe Clarified that the EJB timers distribution and failover rules apply only to persistent timers Clarified that non-persistent timers returned by getTimers and getAllTimers methods are from the same JVM as the caller Fixed section numbering (left over after moving it to its own chapter) in Ch 17 Noted that only 3.0 and 3.1 deployment descriptors are required to be supported in EJB 3.2 Lite for prior versions of the applications Fixes for EJB_SPEC-61 (Ambiguity in EJB lite local view support) and EJB_SPEC-59 (Improve references to the component-defining annotations) JMS/MDB changes: added new standard activation properties and the unique identifier, and rearranged sections for easier navigation Fixed unresolved cross-refs Updated the rule: only local asynchronous session bean invocations are supported in EJB 3.2 Lite Synchronized permissions in the Table with the permissions listed for the EJB Components in the Java EE Platform Specification Table EE.6-2 Specified that during processing of the close() method, the embeddable container cancels all pending asynchronous invocations and non-persistent timers Updated most of the referenced documents to their latest versions Happy reading!

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  • Can it be a good idea to lease a house rather than a standard office-space for a software development shop? [closed]

    - by hamlin11
    Our lease is up on our US-based office-space in July, so it's back on my radar to evaluate our office-space situation. Two of our partners rather like the idea of leasing a house rather than standard office-space. We have 4 partners and one employee. I'm against the idea at this moment in time. Pros, as I see them Easier to get a good location (minimize commutes) All partners/employees have dogs. Easier to work longer hours without dog-duties pulling people back home More comfortable bathroom situation Residential Internet Rate Control of the thermostat Clients don't come to our office, so this would not change our image The additional comfort-level should facilitate a significantly higher-percentage of time "in the zone" for programmers and artists. Cons, as I see them Additional bills to pay (house-cleaning, yard, util, gas, electric) Additional time-overhead in dealing with bills (house-cleaning, yard, util, gas, electric) Additional overhead required to deal with issues that maintenance would have dealt with in a standard office-space Residential neighbors to contend with The equation starts to look a little nasty when factoring in potential time-overhead, especially on issues that a maintenance crew would deal with at a standard office complex. Can this be a good thing for a software development shop?

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  • Performing a Depth First Search iteratively using async/parallel processing?

    - by Prabhu
    Here is a method that does a DFS search and returns a list of all items given a top level item id. How could I modify this to take advantage of parallel processing? Currently, the call to get the sub items is made one by one for each item in the stack. It would be nice if I could get the sub items for multiple items in the stack at the same time, and populate my return list faster. How could I do this (either using async/await or TPL, or anything else) in a thread safe manner? private async Task<IList<Item>> GetItemsAsync(string topItemId) { var items = new List<Item>(); var topItem = await GetItemAsync(topItemId); Stack<Item> stack = new Stack<Item>(); stack.Push(topItem); while (stack.Count > 0) { var item = stack.Pop(); items.Add(item); var subItems = await GetSubItemsAsync(item.SubId); foreach (var subItem in subItems) { stack.Push(subItem); } } return items; } I was thinking of something along these lines, but it's not coming together: var tasks = stack.Select(async item => { items.Add(item); var subItems = await GetSubItemsAsync(item.SubId); foreach (var subItem in subItems) { stack.Push(subItem); } }).ToList(); if (tasks.Any()) await Task.WhenAll(tasks); The language I'm using is C#.

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  • How to set an old view? [closed]

    - by xan
    Possible Duplicate: How to revert to GNOME Classic? is it possible to change general view in Ubuntu 12.04 so it was like in Ubuntu 10.04? I really liked old one and really don't like new one. Things that are annoying me: menu on the left with large icons lack of workspaces icons in right bottom corner lack of menu: Applications, Places, System in left top corner menu like: file | edit | view | help resize and red cross is available in all applications at the very top of the pulpit, unless at the very top of the application window I know it may sound crazy, but that's all me, don't like changes despite that I know they are often good. I would be very grateful for any help. I really want old view (exactly like here: http://upload.wikimedia.org/wikipedia/commons/2/2d/UbuntuMaverickDesktop.png) back. By the way, if I installed Ubuntu 12.04 by WUBI from Windows level on separated partition, then what is the easiest way to uninstall it? Can I simply format this partition? I'm wondering because I don't know if it is safe, what about boot loader etc.

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  • game play strategy in an arena

    - by joulesm
    I am writing a player's behavior for an arena game, and I'm wondering if you can offer some strategies. I'm writing it in Python, but I'm just interested in the high level game play. Here are the game aspects: Arena is a circle of a given size. The arena size shrinks every round to help break ties. Players are much smaller circles, can be on teams of 1 or 2 players. Players attack by colliding with other players, and based on the physics of the collision (speed of both players, angle), one could force another player out of the arena. Once a player is out of the arena, they are out of the game (for that round). The goal is to be the only team with players left in the arena. All other players have been pushed (through collisions or mistakes) out of the arena. It is possible for there to be no winner if the last two players exit the arena at the same time. Once the player has been programmed, the game just runs. There is no human intervention in the game. I'm thinking it's easiest to implement a few simple programmatic rules for my player to follow. For example, stay close to center of the arena, attack opponents from the inner side of the arena, etc. Are there any good simple game strategies? Would adding a random aspect to the game help? For example, to avoid predictability by the other team or something. Thanks in advance.

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  • Can the "Documents" standard folder be rescued and how?

    - by romkyns
    Anyone who likes their Documents folder to contain only things they place there knows that the standard Documents folder is completely unsuitable for this task. Every program seems to want to put its settings, data, or something equally irrelevant into the Documents folder, despite the fact that there are folders specifically for this job. So that this doesn't sound empty, take my personal "Documents" folder as an example. I don't ever use it, in that I never, under any circumstances, save anything into this folder myself. And yet, it contains 46 folders and 3 files at the top level, for a total of 800 files in 500 folders. That's 190 MB of "documents" I didn't create. Obviously any actual documents would immediately get lost in this mess. My question is: can anything be done to improve the situation sufficiently to make "Documents" useful again, say over the next 5 years? Can programmers be somehow educated en-masse not to use it as a dumping ground? Could the OS start reporting some "fake" location hidden under AppData through the existing APIs, while only allowing Explorer and the various Open/Save dialogs to know where the "real" Documents folder resides? Or are any attempts completely futile or even unnecessary?

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  • 25 years old and considering a career change...possible? practical?

    - by mq330
    Hi all, I'm new to this site and new to programming as well. I've spent some time going through an intro cs book that uses python as the language of choice. I find the exercises interesting and engaging and I generally have had a favorable experience programming so far. I've gone through some of the basics with python like writing simple programs, basics of GUIs, manipulating strings, lists, defining functions, etc. And I've always loved technology. Although I've never done any real hardcore programming yet, I was inclined to building websites from a very young age but I never really developed my skills. Now, the thing is I'm 25, I have my bacholors in environmental studies and two masters degrees in urban planning and landscape architecture respectively. I know, it would be quite a departure to pursue a career in programming at this point. Currently, I'm working as a geographic information systems intern. I've taken some GIS classes and have a lot of experience with making maps, doing spatial analysis etc. So what I'm thinking is maybe I can learn some solid programming skills and apply these skills in the field of GIS. From what I've seen, .net languages are the norm in this arena. Could you perhaps provide some guidance to me in terms of what languages I should focus on or courses I should take at this point? What about for building web mapping applications? Also, I was thinking about getting a certificate in programming from a university extension program. Do you think it would be worth it? And furthermore, do you think potential employers would be interested in hiring someone like me (once I get a couple of languages down pretty well) as an intern or in an entry level position? I'll be living in the bay area so I feel that there should be decent opportunities even though I don't have a b.s. in cs.

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  • Opportunities in Cloud Computing

    - by Paul Sorensen
    A recent article from CIO Journal indicates that there is an extreme labor shortage (in certain technology areas) that is is leading to upward pressure on wages for IT Workers. This represents a great opportunity for those with certain skill-sets, among which include Java (Oracle certification is mentioned specifically). The article points out that a key driver of the labor shortage is the expansion of cloud computing. Cloud computing is set up to make life extremely simple for end-users, but the model pushes the complexity to back-end systems which are sophisticated, enterprise-level computing stacks (Oracle has an extensive set of cloud computing solutions). These complex systems require very highly-skilled IT professionals (the best-of-the-best) to successfully develop, implement, administer and maintain them. What this mean for you is that there is opportunity for those who have the appropriate skills at the appropriate levels. If you want to be a part of this opportunity you should do a self-assessment of your own skill-sets and experience. Based upon your results you can decide where it would be most appropriate to spend your time and resources for the highest return on your investment. By expanding and sharpening your skills and by gaining greater experience you will be better prepared to take advantage of career opportunities (like this) that come along periodically. As you evaluate your needs remember that Oracle University has a tremendous selection of high-quality eduction offerings (including training and certification) that can you help move your career forward. Thanks and best of luck!

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  • Ad Service That Lets You Choose Your Ad, and Then Some [on hold]

    - by user3634450
    I'm trying to build an app for both Android and/or iOS where part of the gameplay actually involves ads as a texture. I need to be able to choose which ads I would like to use. I need to be able to be able to identify the ads (which if I can choose which ads show up in the app shouldn't be that hard). I need to be able to swap in and out new ads on what could possibly be a daily basis (and don't want to have to update the app to do it). And as if that wasn't too needy a list, I need to be able to load 50 ads from the pool of ads I deem fit, all to each and every user of the app at least every couple of days. I don't care if the ads pay, I'm not looking for clicks, but I don't want to have to make 50 fake ads every couple of days, from an "artistic" level I don't want the content to feel phony or fake, and I don't really have a way to load content to each user via some internet source (if anyone could name one that would be great). I'm not sure what kind of ad provider would like or even approve of this, in fact just what I've described might be against Google Play's or iTunes' content developer policies, but if anyone could give me any advice to steer me in the right direction it would be greatly appreciated, thank you.

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  • Mechanics of reasoning during programming interviews

    - by user129506
    This is not the usual "I don't want to write code during an interview", in this question the assumption is that I need to write code during an interview (think about the level of rewriting the quicksort or mergesort from scratch) I know how the algorithm work or I have a basic idea of how I should start working from there, i.e. I don't remember the algorithm by heart I noticed that even on a whiteboard, I always end up writing bugged code or code that doesn't compile. If there's a typo, whatever I usually live with that.. but when there's a crash due to some uncaught particular case I end up losing confidence in my skills. I realize that perhaps interviewers might want to look at how I write code and/or how I solve problems rather than proof-compiling my whiteboard code, but I'd like to ask how should I approach the above problem in mental terms, i.e. what mental steps should I follow when writing code for an interview with the two bullet points above. There must be a unique and agreed series of steps I should follow to avoid getting stuck/caught into particular exception cases (limit cases) that might end up wasting my time and my energies rather than focusing on the overall algorithm for the general case. I hope I made my point clear

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  • How-To: Run CMSDK against a RAC cluster

    - by frank.closheim
    Using CMSDK in a production environment often requires a robust, reliable and failover enabled repository. When using Oracle Real Application Cluster (RAC) with your CMSDK repository you need to have a specific configuration in place to support such a setup. This post will explain the configuration steps required when running CMSDK 9.0.4.6 with Oracle WebLogic Server (WLS).In the previous CMSDK 9.0.4.2 version a RAC enabled connect string looked like this: (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = rac1)(PORT = 1521))(ADDRESS = (PROTOCOL = TCP)(HOST = rac2)(PORT = 1521))(LOAD_BALANCE = NO)(FAILOVER = ON)(CONNECT_DATA =(SERVICE_NAME = rac)(failover_mode = (type=select)(method=basic)))CMSDK 9.0.4.6 makes use of data sources to connect to the underlying database. These data sources are configured inside your Application Server, such as Oracle WebLogic Server.In Oracle WebLogic Server 10.3.4, a single data source implementation has been introduced to support an RAC cluster. It responds to Fast Application Notification (FAN) events to provide Fast Connection Failover (FCF), Runtime Connection Load-Balancing (RCLB), and RAC instance graceful shutdown. XA affinity is supported at the global transaction Id level. The new feature is called WebLogic Active GridLink for RAC; which is implemented as the GridLink data source within WebLogic Server.This GridLink data source also works with Oracle Single Client Access Name (SCAN). SCAN is a feature used in RAC environments that provides a single name for clients to access any Oracle Database running in a cluster. You can think of SCAN as a cluster alias for databases in the cluster. The benefit is that the client’s connect information does not need to change if you add or remove nodes or databases in the cluster.The CMSDK 9.0.4.6 documentation describes how to create a regular JDBC data source named jdbc/OracleDS. Please refer to the following document which describes in detail how to create a GridLink data source in WLS.

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  • Splitting a tetris game apart - where to put time-management?

    - by nightcracker
    I am creating a tetris game in C++ & SDL, and I'm trying to do it "good" by making it object-oriented and keeping scopes small. So far I have the following structure: A main with some lowlevel SDL set up and handling input A game class that keeps track of score and provides the interface for main (move block down, etc) A map class that keeps track of the current game field, which blocks are where. Used by the game class. A block class that consists of the current falling block, used by game. A renderer class abstracting low level SDL to a format where you render "tetris blocks". Used by map and block. Now I have a though time where to place the time-management of this game. For example, where should be decided when a block bumps the bottom of the screen how long it takes the current block locks in place and a new block spawns? I also have an other unrelated question, is there some place where you can find some standard data on tetris like standard score tables, rulesets, timings, etc?

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  • Is implementing an interface defined in a subpackage an anti-pattern?

    - by Michael Kjörling
    Let's say I have the following: package me.my.pkg; public interface Something { /* ... couple of methods go here ... */ } and: package me.my; import me.my.pkg.Something; public class SomeClass implements Something { /* ... implementation of Something goes here ... */ /* ... some more method implementations go here too ... */ } That is, the class implementing an interface lives closer to the package hierarchy root than does the interface it implements but they both belong in the same package hierarchy. The reason for this in the particular case I have in mind is that there is a previously-existing package that groups functionality which the Something interface logically belongs to, and the logical (as in both "the one you'd expect" and "the one where it needs to go given the current architecture") implementation class exists previously and lives one level "up" from the logical placement of the interface. The implementing class does not logically belong anywhere under me.my.pkg. In my particular case, the class in question implements several interfaces, but that feels like it doesn't make any (or at least no significant) difference here. I can't decide if this is an acceptable pattern or not. Is it or is it not, and why?

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  • For an ORM supporting data validation, should constraints be enforced in the database as well?

    - by Ramnique Singh
    I have always applied constraints at the database level in addition to my (ActiveRecord) models. But I've been wondering if this is really required? A little background I recently had to unit test a basic automated timestamp generation method for a model. Normally, the test would create an instance of the model and save it without validation. But there are other required fields that aren't nullable at the in the table definition, meaning I cant save the instance even if I skip the ActiveRecord validation. So I'm thinking if I should remove such constraints from the db itself, and let the ORM handle them? Possible advantages if I skip constraints in db, imo - Can modify a validation rule in the model, without having to migrate the database. Can skip validation in testing. Possible disadvantage? If its possible that ORM validation fails or is bypassed, howsoever, the database does not check for constraints. What do you think? EDIT In this case, I'm using the Yii Framework, which generates the model from the database, hence database rules are generated also (though I could always write them post-generation myself too).

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  • decent use-case for goto in c?

    - by Robz
    I really hesitate to ask this, because I don't want to "solicit debate, arguments, polling, or extended discussion" but I'm new to C and want to gain more insight into common patterns used in the language. I recently heard some distaste for the goto command, but I've also recently found a decent use-case for it. Code like this: error = function_that_could_fail_1(); if (!error) { error = function_that_could_fail_2(); if (!error) { error = function_that_could_fail_3(); ...to the n-th tab level! } else { // deal with error, clean up, and return error code } } else { // deal with error, clean up, and return error code } If the clean-up part is all very similar, could be written a little prettier (my opinion?) like this: error = function_that_could_fail_1(); if(error) { goto cleanup; } error = function_that_could_fail_2(); if(error) { goto cleanup; } error = function_that_could_fail_3(); if(error) { goto cleanup; } ... cleanup: // deal with error if it exists, clean up // return error code Is this a common or acceptable use-case of goto in C? Is there a different/better way to do this?

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  • C++ Succinctly now available!

    - by Michael B. McLaughlin
    Over the summer I worked with SyncFusion to create an eBook based off of my C# to C++ guide for their free Succinctly Series of eBooks. Today the result, C++ Succinctly, was published for download. It is a free (registration required; they make tools and libraries for .NET development so you might get an occasional email from them – I’ve been signed up for a few months and have had maybe 3 emails total so it’s not horrible super spam or anything ) and you can download it as a PDF or a Kindle .MOBI file (or both). I’m excited with how it turned out and enjoyed working with the people at SyncFusion. The book contains a total of 20 code samples, which you can download from BitBucket (there’s a link very early in the book). Almost all of the code is also inline in the book itself so that you don’t need to worry about flipping back and forth between your dev machine and your eReader (but if you want to try to understand a concept better, you can easily download the code, open it up in VS 2012, and play around with it to see what happens when you tinker with things). The code does require Visual Studio 2012 because of its expanded support for C++11 features and since I wrote all of the samples as Console programs for clarity and compactness, you will need a version that supports C++ desktop development (currently VS 2012 Pro, Premium, or Ultimate). Sometime this Fall, Microsoft will be releasing Visual Studio 2012 Express for Windows Desktop which should provide a free way to use the samples. That said, I tested all of the samples with MinGW and only the StorageDurationSample will not compile with it due to the thread-local storage code. If you comment that out then you can compile and run all the samples with MinGW (or using a recent version of GCC in a GNU/Linux environment, or any other C++ compiler that provides the same level of C++11 support that Visual Studio 2012 does). I hope it proves helpful to those of you who choose to check it out!

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