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  • Games development with a game loop that's abstracted away

    - by Davy8
    Most game development happens with a main game loop. Are there any good articles/blog posts/discussions about games without a game loop? I imagine they'd mostly be web games, but I'd be interested in hearing otherwise. (As a side note, I think it's really interesting that the concept is almost exclusively used in gaming as far as I'm aware, perhaps that may be another question.) Edit: I realize there's probably a redraw loop somewhere. I guess what I really mean is a loop that is hidden to you. Frames are something you as the developer are not concerned with as you're working on a higher level of abstraction. E.g. someLootItem.moveTo(inventory, someAnimatationType) and that will move from the loot box to your inventory using the specified animation type without the game developer having to worry about the implementation details of that animation. Maybe that's how "real" games end up working, but from reading most tutorials they seem to imply a much more granular level of control is used, but that might just be an artifact of being a tutorial. Edit2: I think most people are misunderstanding what I'm trying to ask, likely because I'm having trouble describing exactly what I'm trying to ask. After some more thinking perhaps what I'm referring to is more along the lines of what I believe is referred to as "scripting" where you're working at a very high level and having some game engine take care of the low level details. For example, take custom maps in Starcraft II or Warcraft III. Many of the "maps" have gameplay that deviates enough from the primary game that they could be considered a separate game written on the same engine. What I'm referring to then is along those lines. I may be wrong because I only dabbed in the Warcraft III editor, but as far as I remember no where in the map editor do you control the game loop, and yet you can create many different games out of it. In my mind, these are games in their own right. If you're playing DotA you don't say you're playing Warcraft III, you say you're playing DotA because that's the actual game you're playing. Such a system may impose limitations that don't exist if you're creating a game from scratch, but it greatly reduces development time because much of the "hard" work has already been done for you. Hopefully that clarifies what I'm asking. Another example of what is I mean, is when you write a web app, of course it communicates through sockets and TCP. But does the average web developer doesn't explicitly write code for connecting sockets. They just need to know about receiving a request and sending a response. There are unique scenarios where you do occasionally need to use raw sockets, but it's generally rare in web development. In a similar fashion, it's very possible to write a game without directly using the game loop, even though one is used behind the scenes. Probably not a AAA title, but there must be hundreds of smaller scale games that can and possibly are written this way. Are there any good resources on writing these "simpler" games?

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  • Stepping outside Visual Studio IDE [Part 2 of 2] with Mono 2.6.4

    - by mbcrump
    Continuing part 2 of my Stepping outside the Visual Studio IDE, is the open-source Mono Project. Mono is a software platform designed to allow developers to easily create cross platform applications. Sponsored by Novell (http://www.novell.com/), Mono is an open source implementation of Microsoft's .NET Framework based on the ECMA standards for C# and the Common Language Runtime. A growing family of solutions and an active and enthusiastic contributing community is helping position Mono to become the leading choice for development of Linux applications. So, to clarify. You can use Mono to develop .NET applications that will run on Linux, Windows or Mac. It’s basically a IDE that has roots in Linux. Let’s first look at the compatibility: Compatibility If you already have an application written in .Net, you can scan your application with the Mono Migration Analyzer (MoMA) to determine if your application uses anything not supported by Mono. The current release version of Mono is 2.6. (Released December 2009) The easiest way to describe what Mono currently supports is: Everything in .NET 3.5 except WPF and WF, limited WCF. Here is a slightly more detailed view, by .NET framework version: Implemented C# 3.0 System.Core LINQ ASP.Net 3.5 ASP.Net MVC C# 2.0 (generics) Core Libraries 2.0: mscorlib, System, System.Xml ASP.Net 2.0 - except WebParts ADO.Net 2.0 Winforms/System.Drawing 2.0 - does not support right-to-left C# 1.0 Core Libraries 1.1: mscorlib, System, System.Xml ASP.Net 1.1 ADO.Net 1.1 Winforms/System.Drawing 1.1 Partially Implemented LINQ to SQL - Mostly done, but a few features missing WCF - silverlight 2.0 subset completed Not Implemented WPF - no plans to implement WF - Will implement WF 4 instead on future versions of Mono. System.Management - does not map to Linux System.EnterpriseServices - deprecated Links to documentation. The Official Mono FAQ’s Links to binaries. Mono IDE Latest Version is 2.6.4 That's it, nothing more is required except to compile and run .net code in Linux. Installation After landing on the mono project home page, you can select which platform you want to download. I typically pick the Virtual PC image since I spend all of my day using Windows 7. Go ahead and pick whatever version is best for you. The Virtual PC image comes with Suse Linux. Once the image is launch, you will see the following: I’m not going to go through each option but its best to start with “Start Here” icon. It will provide you with information on new projects or existing VS projects. After you get Mono installed, it's probably a good idea to run a quick Hello World program to make sure everything is setup properly. This allows you to know that your Mono is working before you try writing or running a more complex application. To write a "Hello World" program follow these steps: Start Mono Development Environment. Create a new Project: File->New->Solution Select "Console Project" in the category list. Enter a project name into the Project name field, for example, "HW Project". Click "Forward" Click “Packaging” then OK. You should have a screen very simular to a VS Console App. Click the "Run" button in the toolbar (Ctrl-F5). Look in the Application Output and you should have the “Hello World!” Your screen should look like the screen below. That should do it for a simple console app in mono. To test out an ASP.NET application, simply copy your code to a new directory in /srv/www/htdocs, then visit the following URL: http://localhost/directoryname/page.aspx where directoryname is the directory where you deployed your application and page.aspx is the initial page for your software. Databases You can continue to use SQL server database or use MySQL, Postgress, Sybase, Oracle, IBM’s DB2 or SQLite db. Conclusion I hope this brief look at the Mono IDE helps someone get acquainted with development outside of VS. As always, I welcome any suggestions or comments.

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  • RPi and Java Embedded GPIO: Big Data and Java Technology

    - by hinkmond
    Java Embedded and Big Data go hand-in-hand, especially as demonstrated by prototyping on a Raspberry Pi to show how well the Java Embedded platform can perform on a small embedded device which then becomes the proof-of-concept for industrial controllers, medical equipment, networking gear or any type of sensor-connected device generating large amounts of data. The key is a fast and reliable way to access that data using Java technology. In the previous blog posts you've seen the integration of a static electricity sensor and the Raspberry Pi through the GPIO port, then accessing that data through Java Embedded code. It's important to point out how this works and why it works well with Java code. First, the version of Linux (Debian Wheezy/Raspian) that is found on the RPi has a very convenient way to access the GPIO ports through the use of Linux OS managed file handles. This is key in avoiding terrible and complex coding using register manipulation in C code, or having to program in a less elegant and clumsy procedural scripting language such as python. Instead, using Java Embedded, allows a fast way to access those GPIO ports through those same Linux file handles. Java already has a very easy to program way to access file handles with a high degree of performance that matches direct access of those file handles with the Linux OS. Using the Java API java.io.FileWriter lets us open the same file handles that the Linux OS has for accessing the GPIO ports. Then, by first resetting the ports using the unexport and export file handles, we can initialize them for easy use in a Java app. // Open file handles to GPIO port unexport and export controls FileWriter unexportFile = new FileWriter("/sys/class/gpio/unexport"); FileWriter exportFile = new FileWriter("/sys/class/gpio/export"); ... // Reset the port unexportFile.write(gpioChannel); unexportFile.flush(); // Set the port for use exportFile.write(gpioChannel); exportFile.flush(); Then, another set of file handles can be used by the Java app to control the direction of the GPIO port by writing either "in" or "out" to the direction file handle. // Open file handle to input/output direction control of port FileWriter directionFile = new FileWriter("/sys/class/gpio/gpio" + gpioChannel + "/direction"); // Set port for input directionFile.write("in"); // Or, use "out" for output directionFile.flush(); And, finally, a RandomAccessFile handle can be used with a high degree of performance on par with native C code (only milliseconds to read in data and write out data) with low overhead (unlike python) to manipulate the data going in and out on the GPIO port, while the object-oriented nature of Java programming allows for an easy way to construct complex analytic software around that data access functionality to the external world. RandomAccessFile[] raf = new RandomAccessFile[GpioChannels.length]; ... // Reset file seek pointer to read latest value of GPIO port raf[channum].seek(0); raf[channum].read(inBytes); inLine = new String(inBytes); It's Big Data from sensors and industrial/medical/networking equipment meeting complex analytical software on a small constraint device (like a Linux/ARM RPi) where Java Embedded allows you to shine as an Embedded Device Software Designer. Hinkmond

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  • Slick2D Rendering Lots of Polygons

    - by Hazzard
    I'm writing an little isometric game using Slick. The world terrain is made up of lots of quadrilaterals. In a small world that is 128 by 128 squares, over 16,000 quadrilaterals need to be rendered. This puts my pretty powerful computer down to 30 fps. I've though about caching "chunks" of the world so only single chunks would ever need updating at a time, but I don't know how to do this, and I am sure there are other ways to optimize it besides that. Maybe I'm doing the whole thing wrong, surely fancy 3D games that run fine on my machine are more intensive than this. My question is how can I improve the FPS and am I doing something wrong? Or does it actually take that much power to render those polygons? -- Here is the source code for the render method in my game state. It iterates through a 2d array or heights and draws polygons based on the height. public void render(GameContainer container, StateBasedGame game, Graphics gfx) throws SlickException { gfx.translate(offsetX * d + container.getWidth() / 2, offsetY * d + container.getHeight() / 2); gfx.scale(d, d); for (int y = 0; y < placeholder.length; y++) {// x & y are isometric // diag for (int x = 0; x < placeholder[0].length; x++) { Polygon poly; int hor = TestState.TILE_WIDTH * (x - y);// hor and ver are orthagonal int W = TestState.TILE_HEIGHT * (x + y) - 1 * heights[y + 1][x];//points to go off of int S = TestState.TILE_HEIGHT * (x + y) - 1 * heights[y + 1][x + 1]; int E = TestState.TILE_HEIGHT * (x + y) - 1 * heights[y][x + 1]; int N = TestState.TILE_HEIGHT * (x + y) - 1 * heights[y][x]; if (placeholder[y][x] == null) { poly = new Polygon();//Create actual surface polygon poly.addPoint(-TestState.TILE_WIDTH + hor, W); poly.addPoint(hor, S + TestState.TILE_HEIGHT); poly.addPoint(TestState.TILE_WIDTH + hor, E); poly.addPoint(hor, N - TestState.TILE_HEIGHT); float z = ((float) heights[y][x + 1] - heights[y + 1][x]) / 32 + 0.5f; placeholder[y][x] = new Tile(poly, new Color(z, z, z)); //ShapeRenderer.fill(placeholder[y][x]); } if (true) {//ONLY draw tile if it's on screen gfx.setColor(placeholder[y][x].getColor()); ShapeRenderer.fill(placeholder[y][x]); //gfx.fill(placeholder[y][x]); //placeholder[y][x]. //DRAW EDGES if (y + 1 == placeholder.length) {//draw South foundation edges gfx.setColor(Color.gray); Polygon found = new Polygon(); found.addPoint(-TestState.TILE_WIDTH + hor, W); found.addPoint(hor, S + TestState.TILE_HEIGHT); found.addPoint(hor, TestState.TILE_HEIGHT * (x + y + 1)); found.addPoint(-TestState.TILE_WIDTH + hor, TestState.TILE_HEIGHT * (x + y)); gfx.fill(found); } if (x + 1 == placeholder[0].length) {//north gfx.setColor(Color.darkGray); Polygon found = new Polygon(); found.addPoint(TestState.TILE_WIDTH + hor, E); found.addPoint(hor, S + TestState.TILE_HEIGHT); found.addPoint(hor, TestState.TILE_HEIGHT * (x + y + 1)); found.addPoint(TestState.TILE_WIDTH + hor, TestState.TILE_HEIGHT * (x + y)); gfx.fill(found); }//*/ } } } }

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  • How the SPARC T4 Processor Optimizes Throughput Capacity: A Case Study

    - by Ruud
    This white paper demonstrates the architected latency hiding features of Oracle’s UltraSPARC T2+ and SPARC T4 processors That is the first sentence from this technical white paper, but what does it exactly mean? Let's consider a very simple example, the computation of a = b + c. This boils down to the following (pseudo-assembler) instructions that need to be executed: load @b, r1 load @c, r2 add r1,r2,r3 store r3, @a The first two instructions load variables b and c from an address in memory (here symbolized by @b and @c respectively). These values go into registers r1 and r2. The third instruction adds the values in r1 and r2. The result goes into register r3. The fourth instruction stores the contents of r3 into the memory address symbolized by @a. If we're lucky, both b and c are in a nearby cache and the load instructions only take a few processor cycles to execute. That is the good case, but what if b or c, or both, have to come from very far away? Perhaps both of them are in the main memory and then it easily takes hundreds of cycles for the values to arrive in the registers. Meanwhile the processor is doing nothing and simply waits for the data to arrive. Actually, it does something. It burns cycles while waiting. That is a waste of time and energy. Why not use these cycles to execute instructions from another application or thread in case of a parallel program? That is exactly what latency hiding on the SPARC T-Series processors does. It is a hardware feature totally transparent to the user and application. As soon as there is a delay in the execution, the hardware uses these otherwise idle cycles to execute instructions from another process. As a result, the throughput capacity of the system improves because idle cycles are no longer wasted and therefore more jobs can be run per unit of time. This feature has been in the SPARC T-series from the beginning, so why this paper? The difference with previous publications on this topic is in the amount of detail given. How this all works under the hood is fully explained using two example programs. Starting from the assembly language instructions, it is demonstrated in what way these programs execute. To really see what is happening we go down to the processor pipeline level, where the gaps in the execution are, and show in what way these idle cycles are filled by other copies of the same program running simultaneously. Both the SPARC T4 as well as the older UltraSPARC T2+ processor are covered. You may wonder why the UltraSPARC T2+ is included. The focus of this work is on the SPARC T4 processor, but to explain the basic concept of latency hiding at this very low level, we start with the UltraSPARC T2+ processor because it is architecturally a much simpler design. From the single issue, in-order pipelines of this processor we then shift gears and cover how this all works on the much more advanced dual issue, out-of-order architecture of the T4. The analysis and performance experiments have been conducted on both processors. The results depend on the processor, but in all cases the theoretical estimates are confirmed by the experiments. If you're interested to read a lot more about this and find out how things really work under the hood, you can download a copy of the paper here. A paper like this could not have been produced without the help of several other people. I want to thank the co-author of this paper, Jared Smolens, for his very valuable contributions and our highly inspiring discussions. I'm also indebted to Thomas Nau (Ulm University, Germany), Shane Sigler and Mark Woodyard (both at Oracle) for their feedback on earlier versions of this paper. Karen Perkins (Perkins Technical Writing and Editing) and Rick Ramsey at Oracle were very helpful in providing editorial and publishing assistance.

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  • Acceptance tests done first...how can this be accomplished?

    - by Crazy Eddie
    The basic gist of most Agile methods is that a feature is not "done" until it's been developed, tested, and in many cases released. This is supposed to happen in quick turnaround chunks of time such as "Sprints" in the Scrum process. A common part of Agile is also TDD, which states that tests are done first. My team works on a GUI program that does a lot of specific drawing and such. In order to provide tests, the testing team needs to be able to work with something that at least attempts to perform the things they are trying to test. We've found no way around this problem. I can very much see where they are coming from because if I was trying to write software that targeted some basically mysterious interface I'd have a very hard time. Although we have behavior fairly well specified, the exact process of interacting with various UI elements when it comes to automation seems to be too unique to a feature to allow testers to write automated scripts to drive something that does not exist. Even if we could, a lot of things end up turning up later as having been missing from the specification. One thing we considered doing was having the testers write test "scripts" that are more like a set of steps that must be performed, as described from a use-case perspective, so that they can be "automated" by a human being. This can then be performed by the developer(s) writing the feature and/or verified by someone else. When the testers later get an opportunity they automate the "script" for regression purposes mainly. This didn't end up catching on in the team though. The testing part of the team is actually falling behind us by quite a margin. This is one reason why the apparently extra time of developing a "script" for a human being to perform just did not happen....they're under a crunch to keep up with us developers. If we waited for them, we'd get nothing done. It's not their fault really, they're a bottle neck but they're doing what they should be and working as fast as possible. The process itself seems to be set up against them. Very often we end up having to go back a month or more in what we've done to fix bugs that the testers have finally gotten to checking. It's an ugly truth that I'd like to do something about. So what do other teams do to solve this fail cascade? How can we get testers ahead of us and how can we make it so that there's actually time for them to write tests for the features we do in a sprint without making us sit and twiddle our thumbs in the meantime? As it's currently going, in order to get a feature "done", using agile definitions, would be to have developers work for 1 week, then testers work the second week, and developers hopefully being able to fix all the bugs they come up with in the last couple days. That's just not going to happen, even if I agreed it was a reasonable solution. I need better ideas...

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  • Organization &amp; Architecture UNISA Studies &ndash; Chap 6

    - by MarkPearl
    Learning Outcomes Discuss the physical characteristics of magnetic disks Describe how data is organized and accessed on a magnetic disk Discuss the parameters that play a role in the performance of magnetic disks Describe different optical memory devices Magnetic Disk The way data is stored on and retried from magnetic disks Data is recorded on and later retrieved form the disk via a conducting coil named the head (in many systems there are two heads) The writ mechanism exploits the fact that electricity flowing through a coil produces a magnetic field. Electric pulses are sent to the write head, and the resulting magnetic patterns are recorded on the surface below with different patterns for positive and negative currents The physical characteristics of a magnetic disk   Summarize from book   The factors that play a role in the performance of a disk Seek time – the time it takes to position the head at the track Rotational delay / latency – the time it takes for the beginning of the sector to reach the head Access time – the sum of the seek time and rotational delay Transfer time – the time it takes to transfer data RAID The rate of improvement in secondary storage performance has been considerably less than the rate for processors and main memory. Thus secondary storage has become a bit of a bottleneck. RAID works on the concept that if one disk can be pushed so far, additional gains in performance are to be had by using multiple parallel components. Points to note about RAID… RAID is a set of physical disk drives viewed by the operating system as a single logical drive Data is distributed across the physical drives of an array in a scheme known as striping Redundant disk capacity is used to store parity information, which guarantees data recoverability in case of a disk failure (not supported by RAID 0 or RAID 1) Interesting to note that the increase in the number of drives, increases the probability of failure. To compensate for this decreased reliability RAID makes use of stored parity information that enables the recovery of data lost due to a disk failure.   The RAID scheme consists of 7 levels…   Category Level Description Disks Required Data Availability Large I/O Data Transfer Capacity Small I/O Request Rate Striping 0 Non Redundant N Lower than single disk Very high Very high for both read and write Mirroring 1 Mirrored 2N Higher than RAID 2 – 5 but lower than RAID 6 Higher than single disk Up to twice that of a signle disk for read Parallel Access 2 Redundant via Hamming Code N + m Much higher than single disk Highest of all listed alternatives Approximately twice that of a single disk Parallel Access 3 Bit interleaved parity N + 1 Much higher than single disk Highest of all listed alternatives Approximately twice that of a single disk Independent Access 4 Block interleaved parity N + 1 Much higher than single disk Similar to RAID 0 for read, significantly lower than single disk for write Similar to RAID 0 for read, significantly lower than single disk for write Independent Access 5 Block interleaved parity N + 1 Much higher than single disk Similar to RAID 0 for read, lower than single disk for write Similar to RAID 0 for read, generally  lower than single disk for write Independent Access 6 Block interleaved parity N + 2 Highest of all listed alternatives Similar to RAID 0 for read; lower than RAID 5 for write Similar to RAID 0 for read, significantly lower than RAID 5  for write   Read page 215 – 221 for detailed explanation on RAID levels Optical Memory There are a variety of optical-disk systems available. Read through the table on page 222 – 223 Some of the devices include… CD CD-ROM CD-R CD-RW DVD DVD-R DVD-RW Blue-Ray DVD Magnetic Tape Most modern systems use serial recording – data is lade out as a sequence of bits along each track. The typical recording used in serial is referred to as serpentine recording. In this technique when data is being recorded, the first set of bits is recorded along the whole length of the tape. When the end of the tape is reached the heads are repostioned to record a new track, and the tape is again recorded on its whole length, this time in the opposite direction. That process continued back and forth until the tape is full. To increase speed, the read-write head is capable of reading and writing a number of adjacent tracks simultaneously. Data is still recorded serially along individual tracks, but blocks in sequence are stored on adjacent tracks as suggested. A tape drive is a sequential access device. Magnetic tape was the first kind of secondary memory. It is still widely used as the lowest-cost, slowest speed member of the memory hierarchy.

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  • apt-get upgrade stuck at the same package

    - by decibyte
    Current status I've started to suspect this is not an Ubuntu issue, but related to the internet connection here at my work. Until I'm sure, Im leaving my question below: Original question I'm stuck, can't upgrade my system. Running sudo apt-get upgrade gives me the following: mmm@alalunga:~$ sudo apt-get upgrade Reading package lists... Done Building dependency tree Reading state information... Done The following packages have been kept back: ginn libgrip0 linux-generic-pae linux-headers-generic-pae linux-image-generic-pae The following packages will be upgraded: apport apport-gtk bind9-host build-essential dhcp3-client dhcp3-common dnsutils eog evince evince-common firefox firefox-branding firefox-dbg firefox-globalmenu firefox-gnome-support firefox-locale-en gimp gimp-data gir1.2-totem-1.0 glib-networking glib-networking-common glib-networking-services gnupg gpgv icedtea-6-jre-cacao icedtea-6-jre-jamvm icedtea-6-plugin icedtea-netx icedtea-netx-common icedtea-plugin isc-dhcp-client isc-dhcp-common libapache2-mod-php5 libart-2.0-2 libbind9-80 libdns81 libevince3-3 libgimp2.0 libisc83 libisccc80 libisccfg82 liblwres80 libssl-dev libssl-doc libssl1.0.0 libtotem0 linux-firmware linux-libc-dev openjdk-6-jre openjdk-6-jre-headless openjdk-6-jre-lib openssl php-pear php5-cli php5-common php5-curl php5-dev php5-gd php5-mysql php5-xsl policykit-1-gnome python-apport python-django python-gst0.10 python-problem-report resolvconf thunderbird thunderbird-globalmenu thunderbird-gnome-support totem totem-common totem-mozilla totem-plugins xserver-xorg-input-synaptics 74 upgraded, 0 newly installed, 0 to remove and 5 not upgraded. Need to get 317 MB/327 MB of archives. After this operation, 1.481 kB of additional disk space will be used. Do you want to continue [Y/n]? Get:1 http://archive.ubuntu.com/ubuntu/ precise-updates/main openjdk-6-jre-headless i386 6b24-1.11.4-1ubuntu0.12.04.1 [27,3 MB] Get:2 http://archive.ubuntu.com/ubuntu/ precise-updates/main openjdk-6-jre-headless i386 6b24-1.11.4-1ubuntu0.12.04.1 [27,3 MB] Get:3 http://archive.ubuntu.com/ubuntu/ precise-updates/main openjdk-6-jre-headless i386 6b24-1.11.4-1ubuntu0.12.04.1 [27,3 MB] Get:4 http://archive.ubuntu.com/ubuntu/ precise-updates/main openjdk-6-jre-headless i386 6b24-1.11.4-1ubuntu0.12.04.1 [27,3 MB] Get:5 http://archive.ubuntu.com/ubuntu/ precise-updates/main openjdk-6-jre-headless i386 6b24-1.11.4-1ubuntu0.12.04.1 [27,3 MB] Get:6 http://archive.ubuntu.com/ubuntu/ precise-updates/main openjdk-6-jre-headless i386 6b24-1.11.4-1ubuntu0.12.04.1 [27,3 MB] Get:7 http://archive.ubuntu.com/ubuntu/ precise-updates/main openjdk-6-jre-headless i386 6b24-1.11.4-1ubuntu0.12.04.1 [27,3 MB] 9% [7 openjdk-6-jre-headless 27,3 MB/27,3 MB 100%] It keeps downloading the package openjdk-6-jre-headless, then does nothing for a while (hanging on what's the last line above), then download the package again. It's at its 13th download attempt at the moment of writing. The actual downloads seem to be done just fine, but whatever it does after downloading seems to be failing. I tried removing openjdk-6, but then it wanted to install openjdk-7 instead, with the same result, hanging at openjdk-7-jre-headless instead. I also tried changing servers from my local (Danish) to the main server. No luck. It's also keeping me from upgrading alle the other packages. What to do? Update After following instructions in the answer by @lpanebr, it is now stuck at the linux-firmware package. So, maybe it's a more general problem than being related to specific package(s)? Although it did download some packages without problems before getting stuck at linux-firmware.

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  • ArchBeat Link-o-Rama Top 10 for November 2012

    - by Bob Rhubart
    Every day ArchBeat searches the web for content created by and for community members, and then shares that content via social media. Here's the list of the Top 10 most popular items posted on the OTN ArchBeat Facebook Page for November 2012. One-Stop Shop for Oracle Webcasts Webcasts can be a great way to get information about Oracle products without having to go cross-eyed reading yet another document off your computer screen. Oracle's new Webcast Center offers selectable filtering to make it easy to get to the information you want. Yes, you have to register to gain access, but that process is quick, and with over 200 webcasts to choose from you know you'll find useful content. OAM/OVD JVM Tuning Vinay from the Oracle Fusion Middleware Architecture Group (otherwise known as the A-Team) shares a process for analyzing and improving performance in Oracle Virtual Directory and Oracle Access Manager. White Paper: Oracle Exalogic Elastic Cloud: Advanced I/O Virtualization Architecture for Consolidating High-Performance Workloads This new white paper by Adam Hawley (with contributions from Yoav Eilat) describes in great detail the incorporation into Oracle Exalogic of virtualized InfiniBand I/O interconnects using Single Root I/O Virtualization (SR-IOV) technology. Architected Systems: "If you don't develop an architecture, you will get one anyway..." "Can you build a system without taking care of architecture?," asks Manuel Ricca. "You certainly can. But inevitably the system will be unbalanced, neglecting the interests of key stakeholders, and problems will soon emerge." Backup and Recovery of an Exalogic vServer via rsync "On Exalogic a vServer will consist of a number of resources from the underlying machine," says the man known only as Donald. "These resources include compute power, networking and storage. In order to recover a vServer from a failure in the underlying rack all of these components have to be thoughts about. This article only discusses the backup and recovery strategies that apply to the storage system of a vServer." This Week on the OTN Architect Community Home Page Make time to check out this week's features on the OTN Solution Architect Homepage, including: SOA Practitioner Guide: Identifying and Discovering Services Technical article by Yuli Vasiliev on Setting Up, Configuring, and Using an Oracle WebLogic Server Cluster Podcast: Are You Future Proof? Clustering ODI11g for High-Availability Part 1: Introduction and Architecture | Richard Yeardley "JEE agents can be deployed alongside, or instead of, standalone agents," says Rittman Meade's Richard Yeardley. "But there is one key advantage in using JEE agents and WebLogic – when you deploy JEE agents as part of a WebLogic cluster they can be configured together to form a high availability cluster." Learn more in Yeardley's extensive post. OIM 11g : Multi-thread approach for writing custom scheduled job | Saravanan V S Saravanan shares insight and expertise relevant to "designing and developing an OIM schedule job that uses multi threaded approach for updating data in OIM using APIs." How to Create Virtual Directory in Weblogic Server | Zeeshan Baig Oracle ACE Zeeshan Baig shows you how in six easy steps. SOA Galore: New Books for Technical Eyes Only Shake up up your technical skills with this trio of new technical books from community members covering SOA and BPM. Thought for the Day "Humans are the best value in computers -- where else can you get a non-linear computer weighing only about 160lbs, having a billion binary decision elements, that can be mass-produced by unskilled labour?" — Anonymous Source: SoftwareQuotes.com

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  • PASS summit 2013. We do not remember days. We remember moments.

    - by Maria Zakourdaev
      "Business or pleasure?" barked the security officer in the Charlotte International Airport. "I’m not sure, sir," I whimpered, immediately losing all courage. "I'm here for the database technologies summit called PASS”. "Sounds boring. Definitely a business trip." Boring?! He couldn’t have been more wrong. If he only knew about the countless meetings throughout the year where I waved my hands at my great boss and explained again and again how fantastic this summit is and how much I learned last year. One by one, the drops of water began eating away at the stone. He finally approved of my trip just to stop me from torturing him. Time moves as slow as a turtle when you are waiting for something. Time runs as fast as a cheetah when you are there. PASS has come...and passed. It’s been an amazing week. Enormous sqlenergy has filled the city, filled the convention center and the surrounding pubs and restaurants. There were awesome speakers, great content, and the chance to meet most inspiring database professionals from all over the world. Some sessions were unforgettable. Imagine a fully packed room with more than 500 people in awed silence, catching each and every one of Paul Randall's words. His tremendous energy and deep knowledge were truly thrilling. No words can describe Rob Farley's unique presentation style, captivating and engaging the audience. When the precious session minutes were over, I could tell that the many random puzzle pieces of information that his listeners knew had been suddenly combined into a clear, cohesive picture. I was amazed as always by Paul White's great sense of humor and his phenomenal ability to explain complicated concepts in a simple way. The keynote by the brilliant Dr. DeWitt from Microsoft in front of the full summit audience of 5000 deeply listening people was genuinely breathtaking. The entire conference throughout offered excellent speakers who inspired me to absorb the knowledge and use it when I got home. To my great surprise, I found that there are other people in this world who like replication as much I do. During the Birds of a Feather Luncheon, SQL Server MVP Ted Krueger was writing a script for replicating the food to other tables. I learned many things at PASS, and not all of them were about SQL. After three summits, this time I finally got the knack of networking. I actually went up and spoke to people, and believe me, that was not easy for an introvert. But this is what the summit is all about. Sqlpeople. They are the ones who make it such an exciting experience. I will be looking forward to the next year. Till then I have my notes and new ideas. How long was the summit? Thousands of unforgettable moments.

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  • Is there a theory for "transactional" sequences of failing and no-fail actions?

    - by Ross Bencina
    My question is about writing transaction-like functions that execute sequences of actions, some of which may fail. It is related to the general C++ principle "destructors can't throw," no-fail property, and maybe also with multi-phase transactions or exception safety. However, I'm thinking about it in language-neutral terms. My concern is with correctly designing error handling in C++ functions that must be reliable. I would like to know what the concepts below are called so that I can learn more about them. I'm sorry that I can't ask the question more directly. Since I don't know this area I have provided an example to explain my question. The question is at the end. Here goes: Consider a sequence of steps or actions executed sequentially, where actions belong to one of two classes: those that always succeed, and those that may fail. In the examples below: S stands for an action that always succeeds (called "no-fail" in some settings). F stands for an action that may fail (for example, it might fail to allocate memory or do I/O that could fail). Consider a sequences of actions (executed sequentially from left to right): S->S->S->S Since each action in the sequence above succeeds, the whole sequence succeeds. On the other hand, the following sequence may fail because the last action may fail: S->S->S->F So, claim: a sequence has the no-fail (S) property if and only if all of its actions are no-fail. Now, I'm interested in action sequences that form "atomic transactions", with "failure atomicity," i.e. where either the whole sequence completes successfully, or there is no effect. I.e. if some action fails, the earlier ones must be rolled back. This requires that any successfully executed actions prior to a failing action must always be able to be rolled back. Consider the sequence: S->S->S->F S<-S<-S In the example above, the first row is the forward path of the transaction, and the second row are inverse actions (executed from right to left) that can be used to roll back if the final top row actions fails. It seems to me that for a transaction to support failure atomicity, the following invariant must hold: Claim: To support failure atomicity (either completion or complete roll-back on failure) all actions preceding the latest failable (F) action on the forward path (marked * in the example below) must have no-fail (S) inverses. The following is an example of a sequence that supports failure atomicity: * S->F->F->F S<-S<-S Further, if we want the transaction to be able to attempt cancellation mid-way through, but still guarantee either full completion or full rollback then we need the following property: Claim: To support failure atomicity and cancellation mid-way through execution, in the face of errors in the inverse (cancellation) path, all actions following the earliest failable (F) inverse on the reverse path (marked *) must be no-fail (S). F->F->F->S->S S<-S<-F<-F * I believe that these two conditions guarantee that an abortable/cancelable transaction will never get "stuck". My questions are: What is the study and theory of these properties called? are my claims correct? and what else is there to know? UPDATE 1: Updated terminology: what I previously called "robustness" is called atomicity in the database literature. UPDATE 2: Added explicit reference to failure atomicity, which seems to be a thing.

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  • Why We Do What We Do. (Part 3 of 5 Part Series on JDE 5G Postponed)

    - by Kem Butller-Oracle
    By Lyle Ekdahl - Oracle JD Edwards Sr. VP General Manager  In the closing of part two of this 5 part blog series, I stated that in the next installment I would explore the expected results of the digital overdrive era and the impact it will have on our economy. While I have full intentions of writing on that topic, I am inspired today to write about something that is top of mind. It’s top of mind because it has come up several times recently conversations with my Oracle’s JD Edwards team members, with customers and our partners, plus I feel passionately about why I do what I do…. It is not what we do but why we do that thing that we do Do you know what you do? For the most part, I bet you could tell me what you do even if your work has changed over the years.  My real question is, “Do you get excited about what you do, and are you fulfilled? Does your work deliver a sense of purpose, a cause to work for, and something to believe in?”  Alright, I guess that was not a single question. So let me just ask, “Why?” Why are you here, right now? Why do you get up in the morning? Why do you go to work? Of course, I can’t answer those questions for you but I can share with you my POV.   For starters, there are several things that drive me. As many of you know by now, I have a somewhat competitive nature but it is not solely the thrill of winning that actually fuels me. Now don’t get me wrong, I do like winning occasionally. However winning is only a potential result of competing and is clearly not guaranteed. So why compete? Why compete in business, and particularly why in this Enterprise Software business?  Here’s why! I am fascinated by creative and building processes. It is about making or producing things, causing something to come into existence. With the right skill, imagination and determination, whether it’s art or invention; the result can deliver value and inspire. In both avocation and vocation I always gravitate towards the create/build processes.  I believe one of the skills necessary for the create/build process is not just the aptitude but also, and especially, the desire and attitude that drives one to gain a deeper understanding. The more I learn about our customers, the more I seek to understand what makes the successful and what difficult issues cause them to struggle. I like to look for the complex, non-commodity process problems where streamlined design and modern technology can provide an easy and simple solution. It is especially gratifying to see our customers use our software to increase their own ability to deliver value to the market. What an incredible network effect! I know many of you share this customer obsession as well as the create/build addiction focused on simple and elegant design. This is what I believe is at the root of our common culture.  Are JD Edwards customers on a whole different than other ERP solutions’ customers? I would argue that for the most part, yes, they are. They selected our software, and our software is different. Why? Because I believe that the create/build process will generally result in solutions that reflect who built it and their culture. And a culture of people focused on why they create/build will attract different customers than one that is based on what is built or how the solution is delivered. In the past I have referred to this idea as character of the customer, and it transcends industry, size and run rate. Now some would argue that JD Edwards has some customers who are characters. But that is for a different post. As I have told you before, the JD Edwards culture is unique, and its resulting economy is valuable and deserving of our best efforts. 

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  • Feynman's inbox

    - by user12607414
    Here is Richard Feynman writing on the ease of criticizing theories, and the difficulty of forming them: The problem is not just to say something might be wrong, but to replace it by something — and that is not so easy. As soon as any really definite idea is substituted it becomes almost immediately apparent that it does not work. The second difficulty is that there is an infinite number of possibilities of these simple types. It is something like this. You are sitting working very hard, you have worked for a long time trying to open a safe. Then some Joe comes along who knows nothing about what you are doing, except that you are trying to open the safe. He says ‘Why don’t you try the combination 10:20:30?’ Because you are busy, you have tried a lot of things, maybe you have already tried 10:20:30. Maybe you know already that the middle number is 32 not 20. Maybe you know as a matter of fact that it is a five digit combination… So please do not send me any letters trying to tell me how the thing is going to work. I read them — I always read them to make sure that I have not already thought of what is suggested — but it takes too long to answer them, because they are usually in the class ‘try 10:20:30’. (“Seeking New Laws”, page 161 in The Character of Physical Law.) As a sometime designer (and longtime critic) of widely used computer systems, I have seen similar difficulties appear when anyone undertakes to publicly design a piece of software that may be used by many thousands of customers. (I have been on both sides of the fence, of course.) The design possibilities are endless, but the deep design problems are usually hidden beneath a mass of superfluous detail. The sheer numbers can be daunting. Even if only one customer out of a thousand feels a need to express a passionately held idea, it can take a long time to read all the mail. And it is a fact of life that many of those strong suggestions are only weakly supported by reason or evidence. Opinions are plentiful, but substantive research is time-consuming, and hence rare. A related phenomenon commonly seen with software is bike-shedding, where interlocutors focus on surface details like naming and syntax… or (come to think of it) like lock combinations. On the other hand, software is easier than quantum physics, and the population of people able to make substantial suggestions about software systems is several orders of magnitude bigger than Feynman’s circle of colleagues. My own work would be poorer without contributions — sometimes unsolicited, sometimes passionately urged on me — from the open source community. If a Nobel prize winner thought it was worthwhile to read his mail on the faint chance of learning a good idea, I am certainly not going to throw mine away. (In case anyone is still reading this, and is wondering what provoked a meditation on the quality of one’s inbox contents, I’ll simply point out that the volume has been very high, for many months, on the Lambda-Dev mailing list, where the next version of the Java language is being discussed. Bravo to those of my colleagues who are surfing that wave.) I started this note thinking there was an odd parallel between the life of the physicist and that of a software designer. On second thought, I’ll bet that is the story for anybody who works in public on something requiring special training. (And that would be pretty much anything worth doing.) In any case, Feynman saw it clearly and said it well.

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  • Utility to Script SQL Server Configuration

    - by Bill Graziano
    I wrote a small utility to script some key SQL Server configuration information. I had two goals for this utility: Assist with disaster recovery preparation Identify configuration changes I’ve released the application as open source through CodePlex. You can download it from CodePlex at the Script SQL Server Configuration project page. The application is a .NET 2.0 console application that uses SMO. It writes its output to a directory that you specify.  Disaster Planning ScriptSqlConfig generates scripts for logins, jobs and linked servers.  It writes the properties and configuration from the instance to text files. The scripts are designed so they can be run against a DR server in the case of a disaster. The properties and configuration will need to be manually compared. Each job is scripted to its own file. Each linked server is scripted to its own file. The linked servers don’t include the password if you use a SQL Server account to connect to the linked server. You’ll need to store those somewhere secure. All the logins are scripted to a single file. This file includes windows logins, SQL Server logins and any server role membership.  The SQL Server logins are scripted with the correct SID and hashed passwords. This means that when you create the login it will automatically match up to the users in the database and have the correct password. This is the only script that I programmatically generate rather than using SMO. The SQL Server configuration and properties are scripted to text files. These will need to be manually reviewed in the event of a disaster. Or you could DIFF them with the configuration on the new server. Configuration Changes These scripts and files are all designed to be checked into a version control system.  The scripts themselves don’t include any date specific information. In my environments I run this every night and check in the changes. I call the application once for each server and script each server to its own directory.  The process will delete any existing files before writing new ones. This solved the problem I had where the scripts for deleted jobs and linked servers would continue to show up.  To see any changes I just need to query the version control system to show many any changes to the files. Database Scripting Utilities that script database objects are plentiful.  CodePlex has at least a dozen of them including one I wrote years ago. The code is so easy to write it’s hard not to include that functionality. This functionality wasn’t high on my list because it’s included in a database backup.  Unless you specify the /nodb option, the utility will script out many user database objects. It will script one object per file. It will script tables, stored procedures, user-defined data types, views, triggers, table types and user-defined functions. I know there are more I need to add but haven’t gotten around it yet. If there’s something you need, please log an issue and get it added. Since it scripts one object per file these really aren’t appropriate to recreate an empty database. They are really good for checking into source control every night and then seeing what changed. I know everyone tells me all their database objects are in source control but a little extra insurance never hurts. Conclusion I hope this utility will help a few of you out there. My goal is to have it script all server objects that aren’t contained in user databases. This should help with configuration changes and especially disaster recovery.

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  • Efficiently separating Read/Compute/Write steps for concurrent processing of entities in Entity/Component systems

    - by TravisG
    Setup I have an entity-component architecture where Entities can have a set of attributes (which are pure data with no behavior) and there exist systems that run the entity logic which act on that data. Essentially, in somewhat pseudo-code: Entity { id; map<id_type, Attribute> attributes; } System { update(); vector<Entity> entities; } A system that just moves along all entities at a constant rate might be MovementSystem extends System { update() { for each entity in entities position = entity.attributes["position"]; position += vec3(1,1,1); } } Essentially, I'm trying to parallelise update() as efficiently as possible. This can be done by running entire systems in parallel, or by giving each update() of one system a couple of components so different threads can execute the update of the same system, but for a different subset of entities registered with that system. Problem In reality, these systems sometimes require that entities interact(/read/write data from/to) each other, sometimes within the same system (e.g. an AI system that reads state from other entities surrounding the current processed entity), but sometimes between different systems that depend on each other (i.e. a movement system that requires data from a system that processes user input). Now, when trying to parallelize the update phases of entity/component systems, the phases in which data (components/attributes) from Entities are read and used to compute something, and the phase where the modified data is written back to entities need to be separated in order to avoid data races. Otherwise the only way (not taking into account just "critical section"ing everything) to avoid them is to serialize parts of the update process that depend on other parts. This seems ugly. To me it would seem more elegant to be able to (ideally) have all processing running in parallel, where a system may read data from all entities as it wishes, but doesn't write modifications to that data back until some later point. The fact that this is even possible is based on the assumption that modification write-backs are usually very small in complexity, and don't require much performance, whereas computations are very expensive (relatively). So the overhead added by a delayed-write phase might be evened out by more efficient updating of entities (by having threads work more % of the time instead of waiting). A concrete example of this might be a system that updates physics. The system needs to both read and write a lot of data to and from entities. Optimally, there would be a system in place where all available threads update a subset of all entities registered with the physics system. In the case of the physics system this isn't trivially possible because of race conditions. So without a workaround, we would have to find other systems to run in parallel (which don't modify the same data as the physics system), other wise the remaining threads are waiting and wasting time. However, that has disadvantages Practically, the L3 cache is pretty much always better utilized when updating a large system with multiple threads, as opposed to multiple systems at once, which all act on different sets of data. Finding and assembling other systems to run in parallel can be extremely time consuming to design well enough to optimize performance. Sometimes, it might even not be possible at all because a system just depends on data that is touched by all other systems. Solution? In my thinking, a possible solution would be a system where reading/updating and writing of data is separated, so that in one expensive phase, systems only read data and compute what they need to compute, and then in a separate, performance-wise cheap, write phase, attributes of entities that needed to be modified are finally written back to the entities. The Question How might such a system be implemented to achieve optimal performance, as well as making programmer life easier? What are the implementation details of such a system and what might have to be changed in the existing EC-architecture to accommodate this solution?

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  • Walkthrough: Scheduling jobs using Quartz.net &ndash; Part 1: What is Quartz.Net?

    - by Tarun Arora
    Quartz.NET is a full-featured, open source enterprise job scheduling system written in .NET platform that can be used from smallest apps to large scale enterprise systems. What is the problem that we trying to address? I want to schedule the execution of a task but only when something happens. Let’s call that something a trigger, so... if the trigger is met => execute the task. Sounds simple, why not use windows task scheduler for this? Well, windows task scheduler is great for tasks where the trigger can be easily defined. With windows task scheduler will you be able to schedule a task to run on every working day according to the UK calendar (exclude all weekends & bank holidays) without either writing the logic for day check in the task or a wrapper script calling into the task. The task should just contain the execution logic and should not have anything to do with the schedule for execution; Quartz.net allows you to achieve this and lots more. A quartz.net trigger gives you the flexibility for task invocation based on the following triggers, 1. at a certain time of day (to the millisecond) 2. on certain days of the week 3. on certain days of the month 4. on certain days of the year 5. not on certain days listed within a registered Calendar (such as business holidays) 6. repeated a specific number of times 7. repeated until a specific time/date 8. repeated indefinitely 9. repeated with a delay interval Did 8 – repeat indefinitely just ring a bell? I’ll be covering that in the future post. Using Quartz.net as a windows service You can have Quartz.net run as a standalone instance within its own .NET virtual machine instance via .NET Remoting. Let’s take a look at typical application architecture. In the figure below, I have the application tier set up on Machine 1, database set up on Machine 2 and Quartz.net set up on Machine 3 which is normally the architecture for most (if not all) enterprise applications. Figure 1 -  Typical Application architecture while using Quartz.net as a windows service What other options do I have if I don’t want to use Quartz.net? Quartz.net is just one of the many job scheduling services. Have a look at this comprehensive list of free and paid enterprise job scheduling software along with their feature comparison. http://en.wikipedia.org/wiki/List_of_job_scheduler_software This was first in the series of posts on enterprise scheduling using Quartz.net, in the next post I’ll be covering how to Install Quartz.net as a windows service. Thank you for taking the time out and reading this blog post. If you enjoyed the post, remember to subscribe to http://feeds.feedburner.com/TarunArora. Stay tuned!

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  • Error X3650 when compiling shader in XNA

    - by Saikai
    I'm attempting to convert the XBDEV.NET Mosaic Shader for use in my XNA project and having trouble. The compiler errors out because of the half globals. At first I tried replacing the globals and just writing the variables explicitly in the code, but that garbles the Output. Next I tried replacing all the half with float vars, but that still garbles the resulting Image. I call the effect file from SpriteBatch.Begin(). Is there a way to convert this shader to the new pixel shader conventions? Are there any good tutorials for this topic? Here is the shader file for reference: /*****************************************************************************/ /* File: tiles.fx Details: Modified version of the NVIDIA Composer FX Demo Program 2004 Produces a tiled mosaic effect on the output. Requires: Vertex Shader 1.1 Pixel Shader 2.0 Modified by: [email protected] (www.xbdev.net) */ /*****************************************************************************/ float4 ClearColor : DIFFUSE = { 0.0f, 0.0f, 0.0f, 1.0f}; float ClearDepth = 1.0f; /******************************** TWEAKABLES *********************************/ half NumTiles = 40.0; half Threshhold = 0.15; half3 EdgeColor = {0.7f, 0.7f, 0.7f}; /*****************************************************************************/ texture SceneMap : RENDERCOLORTARGET < float2 ViewportRatio = { 1.0f, 1.0f }; int MIPLEVELS = 1; string format = "X8R8G8B8"; string UIWidget = "None"; >; sampler SceneSampler = sampler_state { texture = <SceneMap>; AddressU = CLAMP; AddressV = CLAMP; MIPFILTER = NONE; MINFILTER = LINEAR; MAGFILTER = LINEAR; }; /***************************** DATA STRUCTS **********************************/ struct vertexInput { half3 Position : POSITION; half3 TexCoord : TEXCOORD0; }; /* data passed from vertex shader to pixel shader */ struct vertexOutput { half4 HPosition : POSITION; half2 UV : TEXCOORD0; }; /******************************* Vertex shader *******************************/ vertexOutput VS_Quad( vertexInput IN) { vertexOutput OUT = (vertexOutput)0; OUT.HPosition = half4(IN.Position, 1); OUT.UV = IN.TexCoord.xy; return OUT; } /********************************** pixel shader *****************************/ half4 tilesPS(vertexOutput IN) : COLOR { half size = 1.0/NumTiles; half2 Pbase = IN.UV - fmod(IN.UV,size.xx); half2 PCenter = Pbase + (size/2.0).xx; half2 st = (IN.UV - Pbase)/size; half4 c1 = (half4)0; half4 c2 = (half4)0; half4 invOff = half4((1-EdgeColor),1); if (st.x > st.y) { c1 = invOff; } half threshholdB = 1.0 - Threshhold; if (st.x > threshholdB) { c2 = c1; } if (st.y > threshholdB) { c2 = c1; } half4 cBottom = c2; c1 = (half4)0; c2 = (half4)0; if (st.x > st.y) { c1 = invOff; } if (st.x < Threshhold) { c2 = c1; } if (st.y < Threshhold) { c2 = c1; } half4 cTop = c2; half4 tileColor = tex2D(SceneSampler,PCenter); half4 result = tileColor + cTop - cBottom; return result; } /*****************************************************************************/ technique tiles { pass p0 { VertexShader = compile vs_1_1 VS_Quad(); ZEnable = false; ZWriteEnable = false; CullMode = None; PixelShader = compile ps_2_0 tilesPS(); } }

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  • When does a Tumbling Window Start in StreamInsight

    Whilst getting some courseware ready I was playing around writing some code and I decided to very simply show when a window starts and ends based on you asking for a TumblingWindow of n time units in StreamInsight.  I thought this was going to be a two second thing but what I found was something I haven’t yet found documented anywhere until now.   All this code is written in C# and will slot straight into my favourite quick-win dev tool LinqPad   Let’s first create a sample dataset   var EnumerableCollection = new [] { new {id = 1, StartTime = DateTime.Parse("2010-10-01 12:00:00 PM").ToLocalTime()}, new {id = 2, StartTime = DateTime.Parse("2010-10-01 12:20:00 PM").ToLocalTime()}, new {id = 3, StartTime = DateTime.Parse("2010-10-01 12:30:00 PM").ToLocalTime()}, new {id = 4, StartTime = DateTime.Parse("2010-10-01 12:40:00 PM").ToLocalTime()}, new {id = 5, StartTime = DateTime.Parse("2010-10-01 12:50:00 PM").ToLocalTime()}, new {id = 6, StartTime = DateTime.Parse("2010-10-01 01:00:00 PM").ToLocalTime()}, new {id = 7, StartTime = DateTime.Parse("2010-10-01 01:10:00 PM").ToLocalTime()}, new {id = 8, StartTime = DateTime.Parse("2010-10-01 02:00:00 PM").ToLocalTime()}, new {id = 9, StartTime = DateTime.Parse("2010-10-01 03:20:00 PM").ToLocalTime()}, new {id = 10, StartTime = DateTime.Parse("2010-10-01 03:30:00 PM").ToLocalTime()}, new {id = 11, StartTime = DateTime.Parse("2010-10-01 04:40:00 PM").ToLocalTime()}, new {id = 12, StartTime = DateTime.Parse("2010-10-01 04:50:00 PM").ToLocalTime()}, new {id = 13, StartTime = DateTime.Parse("2010-10-01 05:00:00 PM").ToLocalTime()}, new {id = 14, StartTime = DateTime.Parse("2010-10-01 05:10:00 PM").ToLocalTime()} };   Now let’s create a stream of point events   var inputStream = EnumerableCollection .ToPointStream(Application,evt=> PointEvent .CreateInsert(evt.StartTime,evt),AdvanceTimeSettings.StrictlyIncreasingStartTime);   Now we can create our windows over the stream.  The first window we will create is a one hour tumbling window.  We’'ll count the events in the window but what we do here is not the point, the point is our window edges.   var windowedStream = from win in inputStream.TumblingWindow(TimeSpan.FromHours(1),HoppingWindowOutputPolicy.ClipToWindowEnd) select new {CountOfEntries = win.Count()};   Now we can have a look at what we get.  I am only going to show the first non Cti event as that is enough to demonstrate what is going on   windowedStream.ToIntervalEnumerable().First(e=> e.EventKind == EventKind.Insert).Dump("First Row from Windowed Stream");   The results are below   EventKind Insert   StartTime 01/10/2010 12:00   EndTime 01/10/2010 13:00     { CountOfEntries = 5 }   Payload CountOfEntries 5   Now this makes sense and is quite often the width of window specified in examples.  So what happens if I change the windowing code now to var windowedStream = from win in inputStream.TumblingWindow(TimeSpan.FromHours(5),HoppingWindowOutputPolicy.ClipToWindowEnd) select new {CountOfEntries = win.Count()}; Now where does your window start?  What about   var windowedStream = from win in inputStream.TumblingWindow(TimeSpan.FromMinutes(13),HoppingWindowOutputPolicy.ClipToWindowEnd) select new {CountOfEntries = win.Count()};   Well for the first example your window will start at 01/10/2010 10:00:00 , and for the second example it will start at  01/10/2010 11:55:00 Surprised?   Here is the reason why and thanks to the StreamInsight team for listening.   Windows start at TimeSpan.MinValue. Windows are then created from that point onwards of the size you specified in your code.  If a window contains no events they are not produced by the engine to the output.  This is why window start times can be before the first event is created.

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  • How to define template directives (from an API perspective)?

    - by Ralph
    Preface I'm writing a template language (don't bother trying to talk me out of it), and in it, there are two kinds of user-extensible nodes. TemplateTags and TemplateDirectives. A TemplateTag closely relates to an HTML tag -- it might look something like div(class="green") { "content" } And it'll be rendered as <div class="green">content</div> i.e., it takes a bunch of attributes, plus some content, and spits out some HTML. TemplateDirectives are a little more complicated. They can be things like for loops, ifs, includes, and other such things. They look a lot like a TemplateTag, but they need to be processed differently. For example, @for($i in $items) { div(class="green") { $i } } Would loop over $items and output the content with the variable $i substituted in each time. So.... I'm trying to decide on a way to define these directives now. Template Tags The TemplateTags are pretty easy to write. They look something like this: [TemplateTag] static string div(string content = null, object attrs = null) { return HtmlTag("div", content, attrs); } Where content gets the stuff between the curly braces (pre-rendered if there are variables in it and such), and attrs is either a Dictionary<string,object> of attributes, or an anonymous type used like a dictionary. It just returns the HTML which gets plunked into its place. Simple! You can write tags in basically 1 line. Template Directives The way I've defined them now looks like this: [TemplateDirective] static string @for(string @params, string content) { var tokens = Regex.Split(@params, @"\sin\s").Select(s => s.Trim()).ToArray(); string itemName = tokens[0].Substring(1); string enumName = tokens[1].Substring(1); var enumerable = data[enumName] as IEnumerable; var sb = new StringBuilder(); var template = new Template(content); foreach (var item in enumerable) { var templateVars = new Dictionary<string, object>(data) { { itemName, item } }; sb.Append(template.Render(templateVars)); } return sb.ToString(); } (Working example). Basically, the stuff between the ( and ) is not split into arguments automatically (like the template tags do), and the content isn't pre-rendered either. The reason it isn't pre-rendered is because you might want to add or remove some template variables or something first. In this case, we add the $i variable to the template variables, var templateVars = new Dictionary<string, object>(data) { { itemName, item } }; And then render the content manually, sb.Append(template.Render(templateVars)); Question I'm wondering if this is the best approach to defining custom Template Directives. I want to make it as easy as possible. What if the user doesn't know how to render templates, or doesn't know that he's supposed to? Maybe I should pass in a Template instance pre-filled with the content instead? Or maybe only let him tamper w/ the template variables, and then automatically render the content at the end? OTOH, for things like "if" if the condition fails, then the template wouldn't need to be rendered at all. So there's a lot of flexibility I need to allow in here. Thoughts?

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  • A Reusable Builder Class for .NET testing

    - by Liam McLennan
    When writing tests, other than end-to-end integration tests, we often need to construct test data objects. Of course this can be done using the class’s constructor and manually configuring the object, but to get many objects into a valid state soon becomes a large percentage of the testing effort. After many years of painstakingly creating builders for each of my domain objects I have finally become lazy enough to bother to write a generic, reusable builder class for .NET. To use it you instantiate a instance of the builder and configuring it with a builder method for each class you wish it to be able to build. The builder method should require no parameters and should return a new instance of the type in a default, valid state. In other words the builder method should be a Func<TypeToBeBuilt>. The best way to make this clear is with an example. In my application I have the following domain classes that I want to be able to use in my tests: public class Person { public string Name { get; set; } public int Age { get; set; } public bool IsAndroid { get; set; } } public class Building { public string Street { get; set; } public Person Manager { get; set; } } The builder for this domain is created like so: build = new Builder(); build.Configure(new Dictionary<Type, Func<object>> { {typeof(Building), () => new Building {Street = "Queen St", Manager = build.A<Person>()}}, {typeof(Person), () => new Person {Name = "Eugene", Age = 21}} }); Note how Building depends on Person, even though the person builder method is not defined yet. Now in a test I can retrieve a valid object from the builder: var person = build.A<Person>(); If I need a class in a customised state I can supply an Action<TypeToBeBuilt> to mutate the object post construction: var person = build.A<Person>(p => p.Age = 99); The power and efficiency of this approach becomes apparent when your tests require larger and more complex objects than Person and Building. When I get some time I intend to implement the same functionality in Javascript and Ruby. Here is the full source of the Builder class: public class Builder { private Dictionary<Type, Func<object>> defaults; public void Configure(Dictionary<Type, Func<object>> defaults) { this.defaults = defaults; } public T A<T>() { if (!defaults.ContainsKey(typeof(T))) throw new ArgumentException("No object of type " + typeof(T).Name + " has been configured with the builder."); T o = (T)defaults[typeof(T)](); return o; } public T A<T>(Action<T> customisation) { T o = A<T>(); customisation(o); return o; } }

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  • How can I gather client's data on Google App Engine without using Datastore/Backend Instances too much?

    - by ruslan
    One of the projects I'm working on is online survey engine. It's my first big commercial project on Google App Engine. I need your advice on how to collect stats and efficiently record them in DataStore without bankrupting me. Initial requirements are: After user finishes survey client sends list of pairs [ID (int) + PercentHit (double)]. This list shows how close answers of this user match predefined answers of reference answerers (which identified by IDs). I call them "target IDs". Creator of the survey wants to see aggregated % for given IDs for last hour, particular timeframe or from the beginning of the survey. Some surveys may have thousands of target/reference answerers. So I created entity public class HitsStatsDO implements Serializable { @Id transient private Long id; transient private Long version = (long) 0; transient private Long startDate; @Parent transient private Key parent; // fake parent which contains target id @Transient int targetId; private double avgPercent; private long hitCount; } But writing HitsStatsDO for each target from each user would give a lot of data. For instance I had a survey with 3000 targets which was answered by ~4 million people within one week with 300K people taking survey in first day. Even if we assume they were answering it evenly for 24 hours it would give us ~1040 writes/second. Obviously it hits concurrent writes limit of Datastore. I decided I'll collect data for one hour and save that, that's why there are avgPercent and hitCount in HitsStatsDO. GAE instances are stateless so I had to use dynamic backend instance. There I have something like this: // Contains stats for one hour private class Shard { ReadWriteLock lock = new ReentrantReadWriteLock(); Map<Integer, HitsStatsDO> map = new HashMap<Integer, HitsStatsDO>(); // Key is target ID public void saveToDatastore(); public void updateStats(Long startDate, Map<Integer, Double> hits); } and map with shard for current hour and previous hour (which doesn't stay here for long) private HashMap<Long, Shard> shards = new HashMap<Long, Shard>(); // Key is HitsStatsDO.startDate So once per hour I dump Shard for previous hour to Datastore. Plus I have class LifetimeStats which keeps Map<Integer, HitsStatsDO> in memcached where map-key is target ID. Also in my backend shutdown hook method I dump stats for unfinished hour to Datastore. There is only one major issue here - I have only ONE backend instance :) It raises following questions on which I'd like to hear your opinion: Can I do this without using backend instance ? What if one instance is not enough ? How can I split data between multiple dynamic backend instances? It hard because I don't know how many I have because Google creates new one as load increases. I know I can launch exact number of resident backend instances. But how many ? 2, 5, 10 ? What if I have no load at all for a week. Constantly running 10 backend instances is too expensive. What do I do with data from clients while backend instance is dead/restarting?

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  • How to automate a monitoring system for ETL runs

    - by Jeffrey McDaniel
    Upon completion of the Primavera ETL process there are a few ways to determine if the process finished successfully.  First, in the <installation directory>\log folder,  there is a staretlprocess.log and staretl.html files. These files will give the output results of the ETL run. The staretl.html file will give a detailed summary of each step of the process, its run time, and its status. The .log file, based on the logging level set in the Configuration tool, can give extensive information about the ETL process. The log file can be used as a validation for process completion.  To automate the monitoring of these log files, perform the following steps: 1. Write a custom application to parse through the log file and search for [ERROR] . In most cases,  a major [ERROR] could cause the ETL process to fail. Searching the log and finding this value is worthy of an alert. 2. Determine the total number of steps in the ETL process, and validate that the log file recorded and entry for the final step.  For example validate that your log file contains an entry for Step 39/39 (could be different based on the version you are running). If there is no Step 39/39, then either the process is taking longer than expected or it didn't make it to the end.  Either way this would be a good cause for an alert. 3. Check the last line in the log file. The last line of the log file should contain an indication that the ETL run completed successfully. For example, the last line of a log file will say (results could be different based on Reporting Database versions):   [INFO] (Message) Finished Writing Report 4. You could write an Ant script to execute the ETL process and have it set to - failonerror="true" - and from there send results to an external tool to monitor the jobs, send to email, or send to database. With each ETL run, the log file appends to the existing log file by default. Because of this behavior, I would recommend renaming the existing log files before running a new ETL process. By doing this,  only log entries for the currently running ETL process is recorded in the new log files. Based on these log entries, alerts can be setup to notify the administrator or DBA. Another way to determine if the ETL process has completed successfully is to monitor the etl_processmaster table.  Depending on the Reporting Database version this could be in the Stage or Star databases. As of Reporting Database 2.2 and higher this would be in the Star database.  The etl_processmaster table records entries for the ETL run along with a Start and Finish time.  If the ETl process has failed the Finish date should be null. This table can be queried at a time when ETL process is expected to be finished and if null send an alert.  These are just some options. There are additional ways this can be accomplished based around these two areas - log files or database. Here is an additional query to gather more information about your ETL run (connect as Staruser): SELECT SYSDATE,test_script,decode(loc, 0, PROCESSNAME, trim(SUBSTR(PROCESSNAME, loc+1))) PROCESSNAME ,duration duration from ( select (e.endtime - b.starttime) * 1440 duration, to_char(b.starttime, 'hh24:mi:ss') starttime, to_char(e.endtime, 'hh24:mi:ss') endtime,  b.PROCESSNAME, instr(b.PROCESSNAME, ']') loc, b.infotype test_script from ( select processid, infodate starttime, PROCESSNAME, INFOMSG, INFOTYPE from etl_processinfo  where processid = (select max(PROCESSID) from etl_processinfo) and infotype = 'BEGIN' ) b  inner Join ( select processid, infodate endtime, PROCESSNAME, INFOMSG, INFOTYPE from etl_processinfo  where processid = (select max(PROCESSID) from etl_processinfo) and infotype = 'END' ) e on b.processid = e.processid  and b.PROCESSNAME = e.PROCESSNAME order by b.starttime)

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  • Numerically stable(ish) method of getting Y-intercept of mouse position?

    - by Fraser
    I'm trying to unproject the mouse position to get the position on the X-Z plane of a ray cast from the mouse. The camera is fully controllable by the user. Right now, the algorithm I'm using is... Unproject the mouse into the camera to get the ray: Vector3 p1 = Vector3.Unproject(new Vector3(x, y, 0), 0, 0, width, height, nearPlane, farPlane, viewProj; Vector3 p2 = Vector3.Unproject(new Vector3(x, y, 1), 0, 0, width, height, nearPlane, farPlane, viewProj); Vector3 dir = p2 - p1; dir.Normalize(); Ray ray = Ray(p1, dir); Then get the Y-intercept by using algebra: float t = -ray.Position.Y / ray.Direction.Y; Vector3 p = ray.Position + t * ray.Direction; The problem is that the projected position is "jumpy". As I make small adjustments to the mouse position, the projected point moves in strange ways. For example, if I move the mouse one pixel up, it will sometimes move the projected position down, but when I move it a second pixel, the project position will jump back to the mouse's location. The projected location is always close to where it should be, but it does not smoothly follow a moving mouse. The problem intensifies as I zoom the camera out. I believe the problem is caused by numeric instability. I can make minor improvements to this by doing some computations at double precision, and possibly abusing the fact that floating point calculations are done at 80-bit precision on x86, however before I start micro-optimizing this and getting deep into how the CLR handles floating point, I was wondering if there's an algorithmic change I can do to improve this? EDIT: A little snooping around in .NET Reflector on SlimDX.dll: public static Vector3 Unproject(Vector3 vector, float x, float y, float width, float height, float minZ, float maxZ, Matrix worldViewProjection) { Vector3 coordinate = new Vector3(); Matrix result = new Matrix(); Matrix.Invert(ref worldViewProjection, out result); coordinate.X = (float) ((((vector.X - x) / ((double) width)) * 2.0) - 1.0); coordinate.Y = (float) -((((vector.Y - y) / ((double) height)) * 2.0) - 1.0); coordinate.Z = (vector.Z - minZ) / (maxZ - minZ); TransformCoordinate(ref coordinate, ref result, out coordinate); return coordinate; } // ... public static void TransformCoordinate(ref Vector3 coordinate, ref Matrix transformation, out Vector3 result) { Vector3 vector; Vector4 vector2 = new Vector4 { X = (((coordinate.Y * transformation.M21) + (coordinate.X * transformation.M11)) + (coordinate.Z * transformation.M31)) + transformation.M41, Y = (((coordinate.Y * transformation.M22) + (coordinate.X * transformation.M12)) + (coordinate.Z * transformation.M32)) + transformation.M42, Z = (((coordinate.Y * transformation.M23) + (coordinate.X * transformation.M13)) + (coordinate.Z * transformation.M33)) + transformation.M43 }; float num = (float) (1.0 / ((((transformation.M24 * coordinate.Y) + (transformation.M14 * coordinate.X)) + (coordinate.Z * transformation.M34)) + transformation.M44)); vector2.W = num; vector.X = vector2.X * num; vector.Y = vector2.Y * num; vector.Z = vector2.Z * num; result = vector; } ...which seems to be a pretty standard method of unprojecting a point from a projection matrix, however this serves to introduce another point of possible instability. Still, I'd like to stick with the SlimDX Unproject routine rather than writing my own unless it's really necessary.

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  • Introducing the Oracle Linux Playground yum repo

    - by wcoekaer
    We just introduced a new yum repository/channel on http://public-yum.oracle.com called the playground channel. What we started doing is the following: When a new stable mainline kernel is released by Linus or GregKH, we internally build RPMs to test it and do some QA work around it to keep track of what's going on with the latest development kernels. It helps us understand how performance moves up or down and if there are issues, we try to help look into them and of course send that stuff back upstream. Many Linux users out there are interested in trying out the latest features but there are some potential barriers to do this. (1) in general, you are looking at an upstream development distribution, which means that everything changes both in userspace(random applications) and kernel. Projects like Fedora are very useful and someone that wants to just see how the entire distribution evolves with all the changes, this is a great way to be current. A drawback here, though, is that if you have applications that are not part of the distribution, there's a lot of manual work involved or they might just not work because the changes are too drastic. The introduction of systemd is a good example. (2) when you look at many of our customers, that are interested in our database products or applications, the starting point of having a supported/certified userspace/distribution, like Oracle Linux, is a much easier way to get your feet wet in seeing what new/future Linux kernel enhancements could do. This is where the playground channel comes into play. When you install Oracle Linux 6 (which anyone can download and use from http://edelivery.oracle.com/linux), grab the latest public yum repository file http://public-yum.oracle.com/public-yum-ol6.repo, put it in /etc/yum.repos.d and enable the playground repo : [ol6_playground_latest] name=Latest mainline stable kernel for Oracle Linux 6 ($basearch) - Unsupported baseurl=http://public-yum.oracle.com/repo/OracleLinux/OL6/playground/latest/$basearch/ gpgkey=http://public-yum.oracle.com/RPM-GPG-KEY-oracle-ol6 gpgcheck=1 enabled=1 Now, all you need to do : type yum update and you will be downloading the latest stable kernel which will install cleanly on Oracle Linux 6. Thus you end up with a stable Linux distribution where you can install all your software, and then download the latest stable kernel (at time of writing this is 3.6.7) without having to recompile a kernel, without having to jump through hoops. There is of course a big, very important disclaimer this is NOT for PRODUCTION use. We want to try and help make it easy for people that are interested, from a user perspective, where the Linux kernel is going and make it easy to install and use it and play around with new features. Without having to learn how to compile a kernel and without necessarily having to install a complete new distribution with all the changes top to bottom. So we don't or won't introduce any new userspace changes, this project really is around making it easy to try out the latest upstream Linux kernels in a very easy way on an environment that's stable and you can keep current, since all the latest errata for Oracle Linux 6 are published on the public yum repo as well. So one repository location for all your current changes and the upstream kernels. We hope that this will get more users to try out the latest kernel and report their findings. We are always interested in understanding stability and performance characteristics. As new features are going into the mainline kernel, that could potentially be interesting or useful for various products, we will try to point them out on our blogs and give an example on how something can be used so you can try it out for yourselves. Anyway, I hope people will find this useful and that it will help increase interested in upstream development beyond reading lkml by some of the more non-kernel-developer types.

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  • Know your Data Lineage

    - by Simon Elliston Ball
    An academic paper without the footnotes isn’t an academic paper. Journalists wouldn’t base a news article on facts that they can’t verify. So why would anyone publish reports without being able to say where the data has come from and be confident of its quality, in other words, without knowing its lineage. (sometimes referred to as ‘provenance’ or ‘pedigree’) The number and variety of data sources, both traditional and new, increases inexorably. Data comes clean or dirty, processed or raw, unimpeachable or entirely fabricated. On its journey to our report, from its source, the data can travel through a network of interconnected pipes, passing through numerous distinct systems, each managed by different people. At each point along the pipeline, it can be changed, filtered, aggregated and combined. When the data finally emerges, how can we be sure that it is right? How can we be certain that no part of the data collection was based on incorrect assumptions, that key data points haven’t been left out, or that the sources are good? Even when we’re using data science to give us an approximate or probable answer, we cannot have any confidence in the results without confidence in the data from which it came. You need to know what has been done to your data, where it came from, and who is responsible for each stage of the analysis. This information represents your data lineage; it is your stack-trace. If you’re an analyst, suspicious of a number, it tells you why the number is there and how it got there. If you’re a developer, working on a pipeline, it provides the context you need to track down the bug. If you’re a manager, or an auditor, it lets you know the right things are being done. Lineage tracking is part of good data governance. Most audit and lineage systems require you to buy into their whole structure. If you are using Hadoop for your data storage and processing, then tools like Falcon allow you to track lineage, as long as you are using Falcon to write and run the pipeline. It can mean learning a new way of running your jobs (or using some sort of proxy), and even a distinct way of writing your queries. Other Hadoop tools provide a lot of operational and audit information, spread throughout the many logs produced by Hive, Sqoop, MapReduce and all the various moving parts that make up the eco-system. To get a full picture of what’s going on in your Hadoop system you need to capture both Falcon lineage and the data-exhaust of other tools that Falcon can’t orchestrate. However, the problem is bigger even that that. Often, Hadoop is just one piece in a larger processing workflow. The next step of the challenge is how you bind together the lineage metadata describing what happened before and after Hadoop, where ‘after’ could be  a data analysis environment like R, an application, or even directly into an end-user tool such as Tableau or Excel. One possibility is to push as much as you can of your key analytics into Hadoop, but would you give up the power, and familiarity of your existing tools in return for a reliable way of tracking lineage? Lineage and auditing should work consistently, automatically and quietly, allowing users to access their data with any tool they require to use. The real solution, therefore, is to create a consistent method by which to bring lineage data from these data various disparate sources into the data analysis platform that you use, rather than being forced to use the tool that manages the pipeline for the lineage and a different tool for the data analysis. The key is to keep your logs, keep your audit data, from every source, bring them together and use the data analysis tools to trace the paths from raw data to the answer that data analysis provides.

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