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• ROracle support for TimesTen In-Memory Database

  - by Sherry LaMonica

  Today's guest post comes from Jason Feldhaus, a Consulting Member of Technical Staff in the TimesTen Database organization at Oracle.  He shares with us a sample session using ROracle with the TimesTen In-Memory database.  Beginning in version 1.1-4, ROracle includes support for the Oracle Times Ten In-Memory Database, version 11.2.2. TimesTen is a relational database providing very fast and high throughput through its memory-centric architecture.  TimesTen is designed for low latency, high-volume data, and event and transaction management. A TimesTen database resides entirely in memory, so no disk I/O is required for transactions and query operations. TimesTen is used in applications requiring very fast and predictable response time, such as real-time financial services trading applications and large web applications. TimesTen can be used as the database of record or as a relational cache database to Oracle Database. ROracle provides an interface between R and the database, providing the rich functionality of the R statistical programming environment using the SQL query language. ROracle uses the OCI libraries to handle database connections, providing much better performance than standard ODBC.The latest ROracle enhancements include: Support for Oracle TimesTen In-Memory Database Support for Date-Time using R's POSIXct/POSIXlt data types RAW, BLOB and BFILE data type support Option to specify number of rows per fetch operation Option to prefetch LOB data Break support using Ctrl-C Statement caching support Times Ten 11.2.2 contains enhanced support for analytics workloads and complex queries: Analytic functions: AVG, SUM, COUNT, MAX, MIN, DENSE_RANK, RANK, ROW_NUMBER, FIRST_VALUE and LAST_VALUE Analytic clauses: OVER PARTITION BY and OVER ORDER BY Multidimensional grouping operators: Grouping clauses: GROUP BY CUBE, GROUP BY ROLLUP, GROUP BY GROUPING SETS Grouping functions: GROUP, GROUPING_ID, GROUP_ID WITH clause, which allows repeated references to a named subquery block Aggregate expressions over DISTINCT expressions General expressions that return a character string in the source or a pattern within the LIKE predicate Ability to order nulls first or last in a sort result (NULLS FIRST or NULLS LAST in the ORDER BY clause) Note: Some functionality is only available with Oracle Exalytics, refer to the TimesTen product licensing document for details. Connecting to TimesTen is easy with ROracle. Simply install and load the ROracle package and load the driver. > install.packages("ROracle") > library(ROracle) Loading required package: DBI > drv <- dbDriver("Oracle") Once the ROracle package is installed, create a database connection object and connect to a TimesTen direct driver DSN as the OS user. > conn <- dbConnect(drv, username ="", password="", dbname = "localhost/SampleDb_1122:timesten_direct") You have the option to report the server type - Oracle or TimesTen? > print (paste ("Server type =", dbGetInfo (conn)$serverType)) [1] "Server type = TimesTen IMDB" To create tables in the database using R data frame objects, use the function dbWriteTable. In the following example we write the built-in iris data frame to TimesTen. The iris data set is a small example data set containing 150 rows and 5 columns. We include it here not to highlight performance, but so users can easily run this example in their R session. > dbWriteTable (conn, "IRIS", iris, overwrite=TRUE, ora.number=FALSE) [1] TRUE Verify that the newly created IRIS table is available in the database. To list the available tables and table columns in the database, use dbListTables and dbListFields, respectively. > dbListTables (conn) [1] "IRIS" > dbListFields (conn, "IRIS") [1] "SEPAL.LENGTH" "SEPAL.WIDTH" "PETAL.LENGTH" "PETAL.WIDTH" "SPECIES" To retrieve a summary of the data from the database we need to save the results to a local object. The following call saves the results of the query as a local R object, iris.summary. The ROracle function dbGetQuery is used to execute an arbitrary SQL statement against the database. When connected to TimesTen, the SQL statement is processed completely within main memory for the fastest response time. > iris.summary <- dbGetQuery(conn, 'SELECT SPECIES, AVG ("SEPAL.LENGTH") AS AVG_SLENGTH, AVG ("SEPAL.WIDTH") AS AVG_SWIDTH, AVG ("PETAL.LENGTH") AS AVG_PLENGTH, AVG ("PETAL.WIDTH") AS AVG_PWIDTH FROM IRIS GROUP BY ROLLUP (SPECIES)') > iris.summary SPECIES AVG_SLENGTH AVG_SWIDTH AVG_PLENGTH AVG_PWIDTH 1 setosa 5.006000 3.428000 1.462 0.246000 2 versicolor 5.936000 2.770000 4.260 1.326000 3 virginica 6.588000 2.974000 5.552 2.026000 4 <NA> 5.843333 3.057333 3.758 1.199333 Finally, disconnect from the TimesTen Database. > dbCommit (conn) [1] TRUE > dbDisconnect (conn) [1] TRUE We encourage you download Oracle software for evaluation from the Oracle Technology Network. See these links for our software: Times Ten In-Memory Database,  ROracle.  As always, we welcome comments and questions on the TimesTen and  Oracle R technical forums.

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• Code to simulate a users actions, such as logging in

  - by Gortron

  I've recently begun working on a PHP application, replacing another developer. I believed the application was using an API to communicate with a remote service but when I looked through the code I found that it was using a set of functions to actually log in, fill out forms and submit them as a user might do in a browser. My intention is to replace this code, to use the services API instead. I've considered leaving the code as is and not replace it. It makes me wonder though is this a common practice in the software industry? To have a programme simulate a users actions in a browser to perform a set of actions? It feels to me that this is clever but poor programming, Have any other developers seen this?

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• Algorithm to calculate trajectories from vector field

  - by cheeesus

  I have a two-dimensional vector field, i.e., for each point (x, y) I have a vector (u, v), whereas u and v are functions of x and y. This vector field canonically defines a set of trajectories, i.e. a set of paths a particle would take if it follows along the vector field. In the following image, the vector field is depicted in red, and there are four trajectories which are partly visible, depicted in dark red: I need an algorithm which efficiently calculates some trajectories for a given vector field. The trajectories must satisfy some kind of minimum denseness in the plane (for every point in the plane we must have a 'nearby' trajectory), or some other condition to get a reasonable set of trajectories. I could not find anything useful on Google on this, and Stackexchange doesn't seem to handle the topic either. Before I start devising such an algorithm by myself: Are there any known algorithms for this problem? What is their name, for which keywords do I have to search?

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• How essential is it to make a service layer?

  - by BornToCode

  I started building an app in 3 layers (DAL, BL, UI) [it mainly handles CRM, some sales reports and inventory]. A colleague told me that I must move to service layer pattern, that developers came to service pattern from their experience and it is the better approach to design most applications. He said it would be much easier to maintain the application in the future that way. Personally, I get the feeling that it's just making things more complex and I couldn't see much of a benefit from it that would justify that. This app does have an additional small partial ui that uses some (but only few) of the desktop application functions so I did find myself duplicating some code (but not much). Just because of some code duplication I wouldn't convert it to be service oriented, but he said I should use it anyway because in general it's a very good architecture, why programmers are so in love with services?? I tried to google on it but I'm still confused and can't decide what to do.

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• Outline Shader Effect for Orthogonal Geometry in XNA

  - by Griffin

  I just recently started learning the art of shading, but I can't give an outline width to 2D, concave geometry when restrained to a single vertex/pixel shader technique (thanks to XNA). the shape I need to give an outline to has smooth, per-vertex coloring, as well as opacity. The outline, which has smooth, per-vertex coloring, variable width, and opacity cannot interfere with the original shape's colors. A pixel depth border detection algorithm won't work because pixel depth isn't a 3.0 semantic. expanding geometry / redrawing won't work because it interferes with the original shape's colors. I'm wondering if I can do something with the stencil/depth buffer outside of the shader functions since I have access to that through the graphics device. But I don't believe I'm able to manipulate actual values. How might I do this?

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• LuaJit FFI and hiding C implementation details

  - by wirrbel

  I would like to extend an application using LuaJit FFI. Having seen http://luajit.org/ext_ffi_tutorial.html this is surprisingly easy when comparing this to the Lua C API. So far so good. However I do not plainly want to wrap C functions but provide a higher level API to users writing scripts for the application. Especially I do not want users to be able to access "primitives", i.e. the ffi.* namespace. Is this possible or will that ffi namespace be available to user's Lua scripts? On the issue of Sandboxing Lua I found http://lua-users.org/wiki/SandBoxes which is not talking about FFI though. Furthermore, the plan I have described above is assuming that the introduction of abstraction layers happens on the lua side of code. Is this an advisable approach or would you rather abstract functionality on the statically compiled code (on the C-side)?

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• How do I keep co-worker from writing horrible code? [closed]

  - by Drew H

  Possible Duplicate: How do I approach a coworker about his or her code quality? I can handle the for in.. without the hasOwnProperty filtering. I can handle the blatant disregard for the libraries I've used in the past and just using something else. I can even handle the functions with 25 parameters. But I can't handle this. var trips = new Array(); var flights = new Array(); var passengers = new Array(); var persons = new Array(); var requests = new Array(); I've submitted documents on code style, had code reviews, gave him Douglas Crockford's book, shown him presentations, other peoples githubs, etc. He still show the same horrible Javascript style. How else could I approach this guy? Thanks for any help.

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• Is "PHP and MySQL Web Development, 4th ed." an outdated book to learn from?

  - by ForeverLearnNeverMaster

  I want to get into web stuff, and thought of going with PHP+MySQL. I have experience in C#, C++, desktop graphics, but no web stuff besides HTML, CSS which I started learning 2 months ago. On SO PHP-book question, the highest rated book is "PHP Objects, Patterns and Practice". However, I'm not sure if it's a book to start PHP with... or is it? Most of the books mentioned in that SO question seem to be for those who already know PHP. I considered "PHP & MySQL Web Development, 4th Ed.", but someone mentioned that "it uses the mysql_* functions which are almost deprecated." Help?

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• Samsung driver for notebooks in Natty?

  - by burli

  Hi, I have a Samsung N150 Netbook and I installed Unity 11.04 to make some tests. But some functions do not work like backlight and vertical scroll on the touchpad. There are drivers for samsung notbooks and I know that there is a PPA. But not for Natty. Will the drivers be avalible some day in the kernel by default? Will Canonical add these drivers in the kernel, if the Kernel developers wont? I think this would be very usefull because Unity is great for Netbooks and Samsung Netbooks are really nice.

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• Which stages of the requirements analysis process in mobile requirements engineering are the most challenging ones?

  - by user363295

  I'm doing a research on formulating a requirements analysis model as a stage of requirements engineering for mobile-application development by considering the limitations and the needs of it ( agility and etc.. .), what I'm trying to figure out is that which parts of this process (requirements analysis for mobile development) are the most challenging ones ( so i can focus more on) , and if there is any stage that u think I need to include or exclude (exp. some may think a quality plan may or may not be necessary and etc.) to make it more clear below is the list of few of the areas in which I can focus on ( by the way your suggestions can be anything out of the below list.) -Requirements specification -Prototyping -Requirements Prioritization -Focusing on quality functions

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• How to get scripted programs governing game entities run in parallel with a game loop?

  - by Jim

  I recently discovered Crobot which is (briefly) a game where each player codes a virtual robot in a pseudo-C language. Each robot is then put in an arena where it fights against other robots. A robots' source code has this shape : /* Beginning file robot.r */ main() { while (1) { /* Do whatever you want */ ... move(); ... fire(); } } /* End file robot.r */ You can see that : The code is totally independent from any library/include Some predefined functions are available (move, fire, etc…) The program has its own game loop, and consequently is not called every frame My question is: How to achieve a similar result using scripted languages in collaboration with a C/C++ main program ? I found a possible approach using Python, multi-threading and shared memory, although I am not sure yet that it is possible this way. TCP/IP seems a bit too complicated for this kind of application.

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• Recommended Reading for Polishing JavaScript coding style?

  - by wml653

  I've been coding in JavaScript for a while now and am fairly familiar with some of the more advanced coding features of the language (closures, self-executing functions, etc). So my question is, what advanced books/blogs/or anything else would be recommended to help tighten up my coding style? For example, recently I was coding something similar to: var x = ['a', 'b', 'c']; var exists = false; for(var i = 0; i < x.length; i++){ exists = x[i] === 'b' ? true : exists; } But found that the following condensed code would work better: var y = {'a':'', 'b':'', 'c':''}; var exists = 'b' in y; Both store the same value in 'exists', but the second is less common, but much cleaner. Any suggestions for where I should go to learn more tricks like this?

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• How can I improve my Animation

  - by sharethis

  The first approaches in animation for my game relied mostly on sine and cosine functions with the time as parameter. Here is an example of a very basic jump I implemented. if(jumping) { height = sin(time); if(height < 0) jumping = false; // player landed player.position.z = height; } if(keydown(SPACE) && !jumping) { jumping = true; time = now(); // store the starting time } So my player jumped in a perfect sine function. That seems quite natural, because he slows down when he reached the top position, and in the fall he speeds up again. But patching every animation out of sine and cosine is stretched to its limits soon. So can I improve my animation and provide a more abstract layer?

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• Change screen resolution from terminal

  - by Keith

  When I enabled my Nvidia graphics card, it changed the resolution of my screen to larger than my screen. As the result I cannot access any functions that were previously on the right side of my screen. How do I undo this? I originally had 8.04 and was able to change the resolution to whatever I wanted. I'm a new user and can copy and paste commands from a post to terminal mode but that's about it. I have no idea what they are or what they mean.

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• would a composite design pattern be useful for group membership?

  - by changokun

  I'm trying to think about the best way to handle group memberships on a website. People sign up and select checkboxes in a list of interests. Every week we send out interest-themed emails to those members that indicated that interest. however i store the information in the database, while i am working with the lists and generating lists of email addresses or manipulating group memberships, the composite design pattern looked interesting. it would be easy to populate the group, then do some aggregating functions that say... generate the list of email addresses based on the interests. but i'm not sure i'm seeing any other advantages. i do need something scalable, and flexible. thoughts?

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• Plan variable and call dependencies

  - by Gerenuk

  I'd like to write down the design of my program to understand the dependencies and calls better. I know there are class diagrams which show inheritance and attribute variables. However I'd also like to document the input parameters to method functions and in particular which calls the methods function executes inside (e.g. on the input parameters). Also sometimes it might be useful to show how actual objects are connected (if there is a standard structure). This way I can have a better understanding of the modules and design before starting to program. Can you suggest a method to do this software design? It should be one-to-one to programming code structure so that I really notice all quirks beforehand (instead of high-level design where thing are hard to implement without further work). Maybe some special diagram or tool or a combination? It is static dependency and call design rather than time dependent execution monitoring. (I use Python if you have any specialized recommendations).

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• what knowledge would I need to make a good simulation games

  - by Skeith

  I have an idea for a game like theme park but don't know how simulation games are made. I am not some noob on his first game so I appreciated constructive answers instead of "its hard, don't do it". What I want is to know how simulation game mechanics are put together. I figure it would be heaver on the AI than normal games and not knowing much about AI would like to know some programming techniques I should look into for this style game. specific techniques please not just a book on ai. what sort of architecture would be used? I guess it would have some sort of probability engine with pre designed events that are triggered based on the AI state. Would it use a FSM or be purely event driven ? Any information on how a sims game functions would be cool.

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• Oculus Rift with Antichamber

  - by Scott Hainline

  Antichamber runs great on linux (steam version). But it is not playable with the Oculus Rift at this point. The issues are: 1) no headtracking 2) graphics are not being split and distorted by Oculus SDK My current plan is to use LD_PRELOAD to add the functionality, this seems to be the linux equivalent of DLL injection. Antichamber appears to be using SDL, I'm hoping this can be configured to use the headtracking data as a joystick and apply the graphics distortion, but I am not sure which functions I should be looking for. Is there a simpler way of getting these issues resolved? Is SDL the right choice here? Would appreciate any information on how the Unreal Engine 3 works under linux; and library injection too.

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• What is an acceptable GC frequency for a SlimDX/Windows/.NET game?

  - by Rei Miyasaka

  I understand that the Windows GC is much better than the Xbox/WP7 GC, being that it's generational and multithreaded -- so I don't need to worry quite as much about avoiding memory allocation. SlimDX even has some unavoidable functions that generate some amount of garbage (specifically, MapSubresource creates DataBoxes), yet people don't seem to be too upset about it. I'd like to use some functional paradigms to write my code too, which also means creating objects like closures and monads. I know premature optimization isn't a good thing, but are there rules of thumb or metrics that I can follow to know whether I need to cut down on allocations? Is, say, one gen 0 GC per frame too much? One thing that has me stumped is object promotions. Gen 0 GCs will supposedly finish within a millisecond or two, but if I'm understanding correctly, it's the gen 1 and 2 promotions that start to hurt. I'm not too sure how I can predict/prevent these.

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• Handling SMS/email convergence: how does a good business app do it?

  - by Tim Cooper

  I'm writing a school administration software package, but it strikes me that many developers will face this same issue: when communicating with users, should you use email or SMS or both, and should you treat them as fundamentally equivalent channels such that any message can get sent using any media, (with long and short forms of the message template obviously) or should different business functions be specifically tailored to each of the 3? This question got kicked off "StackOverflow" for being overly general, so I'm hoping it's not too general for this site - the answers will no doubt be subjective but "you don't need to write a whole book to answer the question". I'm particularly interested in people who have direct experience of having written comparable business applications. Sub-questions: Do I treat SMS as "moderately secure" and email as less secure? (I'm thinking about booking tokens for parent/teacher nights, permission slips for excursions, absence explanation notes - so high security is not a requirement for us, although medium security is) Is it annoying for users to receive the same message on multiple channels? Should we have a unified framework that reports on delivery or lack thereof of emails and SMS's?

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• run .profile function as cron job

  - by Don

  In the .profile file of the root user I have defined a function, e.g. function printDate() { date } I want to run this function every minute and append the output to cron.log. I tried adding the following crontab entry: * * * * * printDate > $HOME/cron.log 2>&1 But it doesn't work. The cron.log file gets created, but it's empty. I guess this is because the .profile isn't read by cron, so any functions/aliases defined therein are unavailable to it. So I tried changing the crontab entry to: * * * * * source $HOME/.profile;printDate >> $HOME/cron.log 2>&1 But this doesn't work either. It seems cron still doesn't have access to the printDate function because I see the following in cron.log /bin/sh: printDate: not found

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• Webmin - Setting up multiple virtual hosts - Subdomains

  - by Aaron

  Can someone please help me in using WEBMIN to setup virtual hosts. My current domain www.MYDOMAINLOLFAKE.com currently functions. Settings are as follows - Apache - Handles the name-based server www.MYDOMAINLOLFAKE.com on all addresses Address Any Port 80 Server Name www.MYDOMAINLOLFAKE.com Document Root /var/www/html BIND DNS Server - Master Zone MYDOMAINLOLFAKE.com ns1.mydomainlolfake.com IPHERE - works ns2.mydomainlolfake.com IPHERE - works mydomainlolfake.com IPHERE - works www.mydomainlolfake.com IPHERE -works mail.mydomainlolfake.com IPHERE - works ftp.mydomainlolfake.com IPHERE - works What I need - something.mydomainlolfake.com -- CANT GET THIS TO WORK What I tried - Create new virtual host Handles the name-based server something.mydomainlolfake.com on something.mydomainlolfake.com Address Any Port 81 Document Root: /var/www/vhosts/something What happens - I create the new VHOST and then ALL address try to go to that new Document root. I need different addresses to go to their respective folders. Can someone please give me better instructions on how to set that up using webmin? TLDR# How do I make a something.mydomainlolfake.com subdomain work in webmin on my CENTOS 6 web server?

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• How do I manipulate the Url of my Silverlight testpage.aspx?

  - by Daniel

  I am making an XNA game using Silverlight over the web. My testpage.aspx is linked to from a previous page where the client selects certain elements. The testpage.aspx URL changes depending on what I have sent to it. Now in my mainpage.cs file I would like to call certain functions depending on what was passed, but I am unsure how to manipulate or even access the URL. Is there a specific class in the Silverlight library I can use? Thank you for your time.

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• I have a library and several small programs that use it: how should I structure my git repositories?

  - by Dan

  I have some code that uses a library that I and others frequently modify (usually only by adding functions and methods). We each keep a local fork of the library for our own use. I also have a lot of small "driver" programs (~100 lines) that use the library and are used exclusively by me. Currently, I have both the driver programs and the library in the same repository, because I frequently make changes to both that are logically connected (adding a function to the library and then calling it). I'd like to merge my fork of the library with my co-workers' forks, but I don't want the driver programs to be part of the merged library. What's the best way to organize the git repositories for a large, shared library that needs to be merged frequently and a number of small programs that have changes that are connected to changes in the library?

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• Can coding style cause or influence memory fragmentation?

  - by Robert Dailey

  As the title states, I'd like to know if coding style can cause or influence memory fragmentation in a native application, specifically one written using C++. If it does, I'd like to know how. An example of what I mean by coding style is using std::string to represent strings (even static strings) and perform operations on them instead of using the C Library (such as strcmp, strlen, and so on) which can work both on dynamic strings and static strings (the latter point is beneficial since it does not require an additional allocation to access string functions, which is not the case with std::string). A "forward-looking" attitude I have with C++ is to not use the CRT, since to do so would, in a way, be a step backwards. However, such a style results in more dynamic allocations, and especially for a long living application like a server, this causes some speculation that memory fragmentation might become a problem.

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