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• Big Data – Buzz Words: What is HDFS – Day 8 of 21

  - by Pinal Dave

  In yesterday’s blog post we learned what is MapReduce. In this article we will take a quick look at one of the four most important buzz words which goes around Big Data – HDFS. What is HDFS ? HDFS stands for Hadoop Distributed File System and it is a primary storage system used by Hadoop. It provides high performance access to data across Hadoop clusters. It is usually deployed on low-cost commodity hardware. In commodity hardware deployment server failures are very common. Due to the same reason HDFS is built to have high fault tolerance. The data transfer rate between compute nodes in HDFS is very high, which leads to reduced risk of failure. HDFS creates smaller pieces of the big data and distributes it on different nodes. It also copies each smaller piece to multiple times on different nodes. Hence when any node with the data crashes the system is automatically able to use the data from a different node and continue the process. This is the key feature of the HDFS system. Architecture of HDFS The architecture of the HDFS is master/slave architecture. An HDFS cluster always consists of single NameNode. This single NameNode is a master server and it manages the file system as well regulates access to various files. In additional to NameNode there are multiple DataNodes. There is always one DataNode for each data server. In HDFS a big file is split into one or more blocks and those blocks are stored in a set of DataNodes. The primary task of the NameNode is to open, close or rename files and directory and regulate access to the file system, whereas the primary task of the DataNode is read and write to the file systems. DataNode is also responsible for the creation, deletion or replication of the data based on the instruction from NameNode. In reality, NameNode and DataNode are software designed to run on commodity machine build in Java language. Visual Representation of HDFS Architecture Let us understand how HDFS works with the help of the diagram. Client APP or HDFS Client connects to NameSpace as well as DataNode. Client App access to the DataNode is regulated by NameSpace Node. NameSpace Node allows Client App to connect to the DataNode based by allowing the connection to the DataNode directly. A big data file is divided into multiple data blocks (let us assume that those data chunks are A,B,C and D. Client App will later on write data blocks directly to the DataNode. Client App does not have to directly write to all the node. It just has to write to any one of the node and NameNode will decide on which other DataNode it will have to replicate the data. In our example Client App directly writes to DataNode 1 and detained 3. However, data chunks are automatically replicated to other nodes. All the information like in which DataNode which data block is placed is written back to NameNode. High Availability During Disaster Now as multiple DataNode have same data blocks in the case of any DataNode which faces the disaster, the entire process will continue as other DataNode will assume the role to serve the specific data block which was on the failed node. This system provides very high tolerance to disaster and provides high availability. If you notice there is only single NameNode in our architecture. If that node fails our entire Hadoop Application will stop performing as it is a single node where we store all the metadata. As this node is very critical, it is usually replicated on another clustered as well as on another data rack. Though, that replicated node is not operational in architecture, it has all the necessary data to perform the task of the NameNode in the case of the NameNode fails. The entire Hadoop architecture is built to function smoothly even there are node failures or hardware malfunction. It is built on the simple concept that data is so big it is impossible to have come up with a single piece of the hardware which can manage it properly. We need lots of commodity (cheap) hardware to manage our big data and hardware failure is part of the commodity servers. To reduce the impact of hardware failure Hadoop architecture is built to overcome the limitation of the non-functioning hardware. Tomorrow In tomorrow’s blog post we will discuss the importance of the relational database in Big Data. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Big Data, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL

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• Actionscript 3.0 - Enemies do not move right in my platformer game

  - by Christian Basar

  I am making a side-scrolling platformer game in Flash (Actionscript 3.0). I have made lots of progress lately, but I have come across a new problem. I will give some background first. My game level's terrain (or 'floor') is referenced by a MovieClip variable called 'floor.' My desire is to have the Player and enemy characters walk along the terrain. I have gotten the Player character to move on the terrain just fine; he walks up/down hills and falls whenever there is no ground beneath him. Here is the code I created to allow the Player to follow the terrain correctly. Much more code is used to control the Player, but only this code deals with the Player character's following of the terrain and gravity. // If the Player's not on the ground (not touching the 'floor' MovieClip)... if (!onGround) { // Disable ducking downKeyPressed = false; // Increase the Player's 'y' position by his 'y' velocity player.y += playerYVel; } // Increase the 'playerYVel' variable so that the Player will fall // progressively faster down the screen. This code technically // runs "all the time" but in reality it only affects the player // when he's off the ground. playerYVel += gravity; // Give the Player a terminal velocity of 15 px/frame if (playerYVel > 15) { playerYVel = 15; } // If the Player has not hit the 'floor,' increase his falling //speed if (! floor.hitTestPoint(player.x, player.y, true)) { player.y += playerYVel; // The Player is not on the ground when he's not touching it onGround = false; } Since getting this code to work for the Player, I have created a 'SkullDemon' class, which is one of the planned enemies for my game. I want the 'SkullDemon' objects to move along the terrain like the Player does. With lots of great help, I have already coded the EventListeners, etc. necessary for the 'SkullDemons' to move. Unfortunately, I am having trouble getting them to move along the terrain. In fact, they do not touch the terrain at all; they move along the top of the boundary of the 'floor' MovieClip! I had a simple text diagram showing what I mean, but unfortunately Stackoverflow does not format it correctly. I hope my problem is clear from my description. Strangely enough, my code for the Player's movement and the 'SkullDemon's' movement is almost exactly the same, yet the 'SkullDemons' do not move like the Player does. Here is my code for the SkullDemon movement: // Move all of the Skull Demons using this method protected function moveSkullDemons():void { // Go through the whole 'skullDemonContainer' for (var skullDi:int = 0; skullDi < skullDemonContainer.numChildren; skullDi++) { // Set the SkullDemon 'instance' variable to equal the current SkullDemon skullDIns = SkullDemon(skullDemonContainer.getChildAt(skullDi)); // For now, just move the Skull Demons left at 5 units per second skullDIns.x -= 5; // If the Skull Demon has not hit the 'floor,' increase his falling //speed if (! floor.hitTestPoint(skullDIns.x, skullDIns.y, true)) { // Increase the Skull Demon's 'y' position by his 'y' velocity skullDIns.y += skullDIns.sdYVel; // The Skull Demon is not on the ground when he's not touching it skullDIns.sdOnGround = false; } // Increase the 'sdYVel' variable so that the Skull Demon will fall // progressively faster down the screen. This code technically // runs "all the time" but in reality it only affects the Skull Demon // when he's off the ground. if (! skullDIns.sdOnGround) { skullDIns.sdYVel += skullDIns.sdGravity; // Give the Skull Demon a terminal velocity of 15 px/frame if (skullDIns.sdYVel > 15) { skullDIns.sdYVel = 15; } } // What happens when the Skull Demon lands on the ground after a fall? // The Skull Demon is only on the ground ('onGround == true') when // the ground is touching the Skull Demon MovieClip's origin point, // which is at the Skull Demon's bottom centre for (var i:int = 0; i < 10; i++) { // The Skull Demon is only on the ground ('onGround == true') when // the ground is touching the Skull Demon MovieClip's origin point, // which is at the Skull Demon's bottom centre if (floor.hitTestPoint(skullDIns.x, skullDIns.y, true)) { skullDIns.y = skullDIns.y; // Set the Skull Demon's y-axis speed to 0 skullDIns.sdYVel = 0; // The Skull Demon is on the ground again skullDIns.sdOnGround = true; } } } } // End of 'moveSkullDemons()' function It is almost like the 'SkullDemons' are interacting with the 'floor' MovieClip using the hitTestObject() function, and not the hitTestPoint() function which is what I want, and which works for the Player character. I am confused about this problem and would appreciate any help you could give me. Thanks!

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• Managing game state / 'what to update' within an XNA game 'screen'

  - by codinghands

  Note - having read through other GDev questions suggested when writing this question I'm confident this isn't a dupe. Of course, it's 3am and I'm likely wrong, so please mod as such if so. I'm trying to figure out how best to manage state within my game screens - please bare with me though! At the moment I'm using a heavily modified version of the fantastic game state management example on the XNA site available here. This is working perfectly for my 'Screens' - 'IntroScreen' with some shiny logos, 'TitleScreen' and a 'MenuScreen' stacked on top for the title and menu, 'PlayScreen' for the actual gameplay, etc. Each screen has the a bunch of sprites, and an 'Update' and 'Draw', managed by a 'ScreenManager'. In addition to the above, and as suggested as an answer to my other question here, most screens have a 'GameProcessQueue' class full of 'GameProcess'es which lets me do just about anything (animations, youbetcha!), in any order, in sequence or parallel. Why mention all this? When I talk about managing game state I'm thinking more for complex scenarios within a 'Screen'. 'TitleScreen', 'MenuScreen' and the like are all relatively simple. 'Play Screen' less so. How do people manage the different 'states' within the screen (or whatever you call it) that 'does' gameplay? (for me, the 'PlayScreen') I've thought about the following: Enum of different states in the Screen, 'activeState' enum-type variable, switching on the enum in the Screen Update() loop to determine what Screen Update 'sub'-function is called. I can see this getting hairy pretty fast though as screens get more complex and with the 'PlayScreen' becoming a behemoth mega-class. 'State' class with Update loop - a Screen can have any number of 'States', 1+ of which are 'active'. Screen update loop calls update on all active states. States themselves know which screen they belong to, and may even belong to a 'StateManager' which handles transitioning from one state to the next. Once a state is over it's removed from the ScreenState list. The Screen doesn't need a bunch of GameProcessQueues, each State has its own. Abstract Screen further to be more flexible - I can see the similarities between what I've got (game 'Screens' handled by a ScreenManager) and what I want (states within a screen, and a mechanism to manage them). However at the moment I see 'Screens' as high level and very distinct ('PlayScreen' with baddies != 'MenuScreen' with 4 words and event handlers), where as my proposed 'States' are more intrinsically tied to a specific screen with complex requirements. I think. This is for a turn-based board game, so it's easier to define things as a discrete series of steps (IntroAnimation - P1Turn - P2Turn - P1Turn ... - GameOver - .... Obviously with an open-world RPG things are very different, but any advice in this scenario is appreciated. If I'm just going OOP-crazy please say so. Similarly I'm concious there's a huge amount on this site re: state management. But as my first 'serious' game after a couple of false starts I'd like to get this right, and would rather be harassed and modded down than never ask :)

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• Oracle Fusion Supply Chain Management (SCM) Designs May Improve End User Productivity

  - by Applications User Experience

  By Applications User Experience on March 10, 2011 Michele Molnar, Senior Usability Engineer, Applications User Experience The Challenge: The SCM User Experience team, in close collaboration with product management and strategy, completely redesigned the user experience for Oracle Fusion applications. One of the goals of this redesign was to increase end user productivity by applying design patterns and guidelines and incorporating findings from extensive usability research. But a question remained: How do we know that the Oracle Fusion designs will actually increase end user productivity? The Test: To answer this question, the SCM Usability Engineers compared Oracle Fusion designs to their corresponding existing Oracle applications using the workflow time analysis method. The workflow time analysis method breaks tasks into a sequence of operators. By applying standard time estimates for all of the operators in the task, an estimate of the overall task time can be calculated. The workflow time analysis method has been recently adopted by the Applications User Experience group for use in predicting end user productivity. Using this method, a design can be tested and refined as needed to improve productivity even before the design is coded. For the study, we selected some of our recent designs for Oracle Fusion Product Information Management (PIM). The designs encompassed tasks performed by Product Managers to create, manage, and define products for their organization. (See Figure 1 for an example.) In applying this method, the SCM Usability Engineers collaborated with Product Management to compare the new Oracle Fusion Applications designs against Oracle’s existing applications. Together, we performed the following activities: Identified the five most frequently performed tasks Created detailed task scenarios that provided the context for each task Conducted task walkthroughs Analyzed and documented the steps and flow required to complete each task Applied standard time estimates to the operators in each task to estimate the overall task completion time Figure 1. The interactions on each Oracle Fusion Product Information Management screen were documented, as indicated by the red highlighting. The task scenario and script provided the context for each task.  The Results: The workflow time analysis method predicted that the Oracle Fusion Applications designs would result in productivity gains in each task, ranging from 8% to 62%, with an overall productivity gain of 43%. All other factors being equal, the new designs should enable these tasks to be completed in about half the time it takes with existing Oracle Applications. Further analysis revealed that these performance gains would be achieved by reducing the number of clicks and screens needed to complete the tasks. Conclusions: Using the workflow time analysis method, we can expect the Oracle Fusion Applications redesign to succeed in improving end user productivity. The workflow time analysis method appears to be an effective and efficient tool for testing, refining, and retesting designs to optimize productivity. The workflow time analysis method does not replace usability testing with end users, but it can be used as an early predictor of design productivity even before designs are coded. We are planning to conduct usability tests later in the development cycle to compare actual end user data with the workflow time analysis results. Such results can potentially be used to validate the productivity improvement predictions. Used together, the workflow time analysis method and usability testing will enable us to continue creating, evaluating, and delivering Oracle Fusion designs that exceed the expectations of our end users, both in the quality of the user experience and in productivity. (For more information about studying productivity, refer to the Measuring User Productivity blog.)

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• Must go through Windows Boot Loader to get to Grub

  - by Zach

  I just installed a fresh copy of Precise alongside Windows 7. I have to separate 750GB hard drives; /dev/sda holds the Windows partitions and /dev/sdb holds the Ubuntu partitions. Other than that, these are fresh installs of both Windows 7 and Ubuntu 12.04. Whenever I boot, Grub doesn't load, instead it goes to a black screen with a single blinking (horizontal bar) cursor in the top right corner. However, if I boot, hit escape right as the BIOS/POST screen finishes up, see the Windows Boot Loader and hit escape to make it go back to the BIOS screen. After the BIOS screen, grub shows up and everything functions normally; I can boot into Ubuntu or Win7. I don't want to have to do the Escape, Escape, Wait, Boot trick every time. I have no idea what would be wrong or what information I could give you guys to help diagnose. I have run a sudo update-grub and it found everything normally. I tried adding nomodeset flag in the /etc/default/grub line GRUB_CMDLINE_LINUX_DEFAULT which searching around made me think might work. Thoughts on what I could do to fix this? EDIT: I've tried changing the boot order so that both drives in the BIOS (both are labeled as "Internal HDD") have had a try booting first. I think the problem may be that every time I boot, the BIOS boot order is different... and I have to reset it. It seems to not be stable... but I'm not sure how to go about fixing that either. The machine has both traditional BIOS and UEFI. It came standard in "Legacy" mode; so it is currently set to boot through Legacy mode. I've reinstalled Ubuntu now, and now if I hit escape at the end of the BIOS/POST startup screen, it takes me to GRUB menu. Otherwise it automatically loads Windows. It seems like GRUB is now the acting bootloader, it just doesn't automatically start that unless I ask it to open a bootloader. In my other machines, it has always automatically started at the end of BIOS/POST. EDIT2: Using gparted, I just looked at my partitions, it would seem that my linux-swap partition is currently flagged as the boot partition for my Ubuntu install. I currently only have 2 partitions: one of "ext4" with a mount point of "/" and flag " "; and the "linux-swap" with mount point " " and flag "boot." If I change the boot flag to be on "/," it does not reliably solve the problem. After 10 boots: 2 Booted successfully to GRUB 5 Booted directly to Windows 7 3 booted to the black screen with the cursor and hung there Further research makes me think this is an issue of the BIOS not reliably booting hard drives in the same order or not finding both hard drives. If I ask it to create a "boot menu" sometimes it has 2 entries for "Internal HDD," sometimes 1. Also the list it creates changes order every time I bring it up; so it is not following a consistent boot sequence. Will report back if this is not an issue with GRUB.

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• PASS Summit 2013 Review

  - by Ajarn Mark Caldwell

  As a long-standing member of PASS who lives in the greater Seattle area and has attended about nine of these Summits, let me start out by saying how GREAT it was to go to Charlotte, North Carolina this year.  Many of the new folks that I met at the Summit this year, upon hearing that I was from Seattle, commented that I must have been disappointed to have to travel to the Summit this year after 5 years in a row in Seattle.  Well, nothing could be further from the truth.  I cheered loudly when I first heard that the 2013 Summit would be outside Seattle.  I have many fond memories of trips to Orlando, Florida and Grapevine, Texas for past Summits (missed out on Denver, unfortunately).  And there is a funny dynamic that takes place when the conference is local.  If you do as I have done the last several years and saved my company money by not getting a hotel, but rather just commuting from home, then both family and coworkers tend to act like you’re just on a normal schedule.  For example, I have a young family, and my wife and kids really wanted to still see me come home “after work”, but there are a whole lot of after-hours activities, social events, and great food to be enjoyed at the Summit each year.  Even more so if you really capitalize on the opportunities to meet face-to-face with people you either met at previous summits or have spoken to or heard of, from Twitter, blogs, and forums.  Then there is also the lovely commuting in Seattle traffic from neighboring cities rather than the convenience of just walking across the street from your hotel.  So I’m just saying, there are really nice aspects of having the conference 2500 miles away. Beyond that, the training was fantastic as usual.  The SQL Server community has many outstanding presenters and experts with deep knowledge of the tools who are extremely willing to share all of that with anyone who wants to listen.  The opening video with PASS President Bill Graziano in a NASCAR race turned dream sequence was very well done, and the keynotes, as usual, were great.  This year I was particularly impressed with how well attended were the Professional Development sessions.  Not too many years ago, those were very sparsely attended, but this year, the two that I attended were standing-room only, and these were not tiny rooms.  I would say this is a testament to both the maturity of the attendees realizing how important these topics are to career success, as well as to the ever-increasing skills of the presenters and the program committee for selecting speakers and topics that resonated with people.  If, as is usually the case, you were not able to get to every session that you wanted to because there were just too darn many good ones, I encourage you to get the recordings. Overall, it was a great time as these events always are.  It was wonderful to see old friends and make new ones, and the people of Charlotte did an awesome job hosting the event and letting their hospitality shine (extra kudos to SQLSentry for all they did with the shuttle, maps, and other event sponsorships).  We’re back in Seattle next year (it is a release year, after all) but I would say that with the success of this year’s event, I strongly encourage the Board and PASS HQ to firmly reestablish the location rotation schedule.  I’ll even go so far as to suggest standardizing on an alternating Seattle – Charlotte schedule, or something like that. If you missed the Summit this year, start saving now, and register early, so you can join us!

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• how to write the code for this program specially in mathematica? [closed]

  - by asd

  I implemented a solution to the problem below in Mathematica, but it takes a very long time (hours) to compute f of kis or the set B for large numbers. Somebody suggested that implementing this in C++ resulted in a solution in less than 10 minutes. Would C++ be a good language to learn to solve these problems, or can my Mathematica code be improved to fix the performance issues? I don't know anything about C or C++ and it should be difficult to start to learn this languages. I prefer to improve or write new code in mathematica. Problem Description Let $f$ be an arithmetic function and A={k1,k2,...,kn} are integers in increasing order. Now I want to start with k1 and compare f(ki) with f(k1). If f(ki)f(k1), put ki as k1. Now start with ki, and compare f(kj) with f(ki), for ji. If f(kj)f(ki), put kj as ki, and repeat this procedure. At the end we will have a sub sequence B={L1,...,Lm} of A by this property: f(L(i+1))f(L(i)), for any 1<=i<=m-1 For example, let f is the divisor function of integers. Here I put some part of my code and this is just a sample and the question in my program could be more larger than these: «««««««««««««««««««««««««««««««««««« f[n_] := DivisorSigma[0, n]; g[n_] := Product[Prime[i], {i, 1, PrimePi[n]}]; k1 = g[67757] g[353] g[59] g[19] g[11] g[7] g[5]^2 6^3 2^7; k2 = g[67757] g[353] g[59] g[19] g[11] g[7] g[5] 6^5 2^7; k3 = g[67757] g[359] g[53] g[19] g[11] g[7] g[5] 6^4 2^7; k4 = g[67759] g[349] g[53] g[19] g[11] g[7] g[5] 6^5 2^6; k5 = g[67757] g[359] g[53] g[19] g[11] g[7] g[5] 6^4 2^8; k6 = g[67759] g[349] g[53] g[19] g[11] g[7] g[5]^2 6^3 2^7; k7 = g[67757] g[359] g[53] g[19] g[11] g[7] g[5] 6^5 2^6; k8 = g[67757] g[359] g[53] g[19] g[11] g[7] g[5] 6^4 2^9; k9 = g[67757] g[359] g[53] g[19] g[11] g[7] g[5]^2 6^3 2^7; k10 = g[67757] g[359] g[53] g[19] g[11] g[7] g[5] 6^5 2^7; k11 = g[67759] g[349] g[53] g[19] g[11] g[7] g[5]^2 6^4 2^6; k12 = g[67757] g[359] g[53] g[19] g[11] g[7] g[5]^2 6^3 2^8; k13 = g[67757] g[359] g[53] g[19] g[11] g[7] g[5]^2 6^4 2^6; k14 = g[67757] g[359] g[53] g[19] g[11] g[7] g[5]^2 6^3 2^9; k15 = g[67757] g[359] g[53] g[19] g[11] g[7] g[5]^2 6^4 2^7; k16 = g[67757] g[359] g[53] g[23] g[11] g[7] g[5] 6^4 2^8; k17 = g[67757] g[359] g[59] g[19] g[11] g[7] g[5] 6^4 2^7; k18 = g[67757] g[359] g[53] g[23] g[11] g[7] g[5] 6^4 2^9; k19 = g[67759] g[353] g[53] g[19] g[11] g[7] g[5] 6^4 2^6; k20 = g[67763] g[347] g[53] g[19] g[11] g[7] g[5] 6^4 2^7; k = Table[k1, k2, k3, k4, k5, k6, k7, k8, k9, k10, k11, k12, k13, k14, k15, k16, k17, k18, k19, k20]; i = 1; count = 0; For[j = i, j <= 20, j++, If[f[k[[j]]] - f[k[[i]]] > 0, i = j; Print["k",i]; count = count + 1]]; Print["count= ", count] ««««««««««««««««««««««««««««««««««««

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• SPTI problem with Mode Select

  - by Bob Murphy

  I'm running into a problem in which an attempt to do a "Mode Select" SCSI command using SPTI is returning an error status of 0x02 ("Check Condition"), and hope someone here might have some tips or suggestions. The code in question is intended to work with at a custom SCSI device. I wrote the original support for it using ASPI under WinXP, and am converting it to work with SPTI under 64-bit Windows 7. Here's the problematic code - and what's happening is, sptwb.spt.ScsiStatus is 2, which is a "Check Condition" error. Unfortunately, the device in question doesn't return useful information when you do a "Request Sense" after this problem occurs, so that's no help. void MSSModeSelect(const ModeSelectRequestPacket& inRequest, StatusResponsePacket& outResponse) { IPC_LOG("MSSModeSelect(): PathID=%d, TargetID=%d, LUN=%d", inRequest.m_Device.m_PathId, inRequest.m_Device.m_TargetId, inRequest.m_Device.m_Lun); int adapterIndex = inRequest.m_Device.m_PathId; HANDLE adapterHandle = prvOpenScsiAdapter(inRequest.m_Device.m_PathId); if (adapterHandle == INVALID_HANDLE_VALUE) { outResponse.m_Status = eScsiAdapterErr; return; } SCSI_PASS_THROUGH_WITH_BUFFERS sptwb; memset(&sptwb, 0, sizeof(sptwb)); #define MODESELECT_BUF_SIZE 32 sptwb.spt.Length = sizeof(SCSI_PASS_THROUGH); sptwb.spt.PathId = inRequest.m_Device.m_PathId; sptwb.spt.TargetId = inRequest.m_Device.m_TargetId; sptwb.spt.Lun = inRequest.m_Device.m_Lun; sptwb.spt.CdbLength = CDB6GENERIC_LENGTH; sptwb.spt.SenseInfoLength = 0; sptwb.spt.DataIn = SCSI_IOCTL_DATA_IN; sptwb.spt.DataTransferLength = MODESELECT_BUF_SIZE; sptwb.spt.TimeOutValue = 2; sptwb.spt.DataBufferOffset = offsetof(SCSI_PASS_THROUGH_WITH_BUFFERS,ucDataBuf); sptwb.spt.Cdb[0] = SCSIOP_MODE_SELECT; sptwb.spt.Cdb[4] = MODESELECT_BUF_SIZE; DWORD length = offsetof(SCSI_PASS_THROUGH_WITH_BUFFERS,ucDataBuf) + sptwb.spt.DataTransferLength; memset(sptwb.ucDataBuf, 0, sizeof(sptwb.ucDataBuf)); sptwb.ucDataBuf[2] = 0x10; sptwb.ucDataBuf[16] = (BYTE)0x01; ULONG bytesReturned = 0; BOOL okay = DeviceIoControl(adapterHandle, IOCTL_SCSI_PASS_THROUGH, &sptwb, sizeof(SCSI_PASS_THROUGH), &sptwb, length, &bytesReturned, FALSE); DWORD gle = GetLastError(); IPC_LOG(" DeviceIoControl() %s", okay ? "worked" : "failed"); if (okay) { outResponse.m_Status = (sptwb.spt.ScsiStatus == 0) ? eOk : ePrinterStatusErr; } else { outResponse.m_Status = eScsiPermissionsErr; } CloseHandle(adapterHandle); } A few more remarks, for what it's worth: This is derived from some old ASPI code that does the "Mode Select" flawlessly. This routine opens \\.\SCSI<whatever> at the beginning, via prvOpenScsiAdapter(), and closes the handle at the end. All the other routines for dealing with the device do the same thing, including the routine to do "Reserve Unit". Is this a good idea under SPTI, or should the call to "Reserve Unit" leave the handle open, so this routine and others in the sequence can use the same handle? This uses the IOCTL_SCSI_PASS_THROUGH. Should "Mode Select" use IOCTL_SCSI_PASS_THROUGH_DIRECT instead? Thanks in advance - any help will be greatly appreciated.

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• Documentation and Test Assertions in Databases

  - by Phil Factor

  When I first worked with Sybase/SQL Server, we thought our databases were impressively large but they were, by today’s standards, pathetically small. We had one script to build the whole database. Every script I ever read was richly annotated; it was more like reading a document. Every table had a comment block, and every line would be commented too. At the end of each routine (e.g. procedure) was a quick integration test, or series of test assertions, to check that nothing in the build was broken. We simply ran the build script, stored in the Version Control System, and it pulled everything together in a logical sequence that not only created the database objects but pulled in the static data. This worked fine at the scale we had. The advantage was that one could, by reading the source code, reach a rapid understanding of how the database worked and how one could interface with it. The problem was that it was a system that meant that only one developer at the time could work on the database. It was very easy for a developer to execute accidentally the entire build script rather than the selected section on which he or she was working, thereby cleansing the database of everyone else’s work-in-progress and data. It soon became the fashion to work at the object level, so that programmers could check out individual views, tables, functions, constraints and rules and work on them independently. It was then that I noticed the trend to generate the source for the VCS retrospectively from the development server. Tables were worst affected. You can, of course, add or delete a table’s columns and constraints retrospectively, which means that the existing source no longer represents the current object. If, after your development work, you generate the source from the live table, then you get no block or line comments, and the source script is sprinkled with silly square-brackets and other confetti, thereby rendering it visually indigestible. Routines, too, were affected. In our system, every routine had a directly attached string of unit-tests. A retro-generated routine has no unit-tests or test assertions. Yes, one can still commit our test code to the VCS but it’s a separate module and teams end up running the whole suite of tests for every individual change, rather than just the tests for that routine, which doesn’t scale for database testing. With Extended properties, one can get the best of both worlds, and even use them to put blame, praise or annotations into your VCS. It requires a lot of work, though, particularly the script to generate the table. The problem is that there are no conventional names beyond ‘MS_Description’ for the special use of extended properties. This makes it difficult to do splendid things such ensuring the integrity of the build by running a suite of tests that are actually stored in extended properties within the database and therefore the VCS. We have lost the readability of database source code over the years, and largely jettisoned the use of test assertions as part of the database build. This is not unexpected in view of the increasing complexity of the structure of databases and number of programmers working on them. There must, surely, be a way of getting them back, but I sometimes wonder if I’m one of very few who miss them.

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• Context is Everything

  - by Angus Graham

  Normal 0 false false false EN-CA X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin;} Context is Everything How many times have you have you asked a question only to hear an answer like “Well, it depends. What exactly are you trying to do?”.  There are times that raw information can’t tell us what we need to know without putting it in a larger context. Let's take a real world example.  If I'm a maintenance planner trying to figure out which assets should be replaced during my next maintenance window, I'm going to go to my Asset Management System.  I can get it to spit out a list of assets that have failed several times over the last year.  But what are these assets connected to?  Is there any safety consequences to shutting off this pipeline to do the work?  Is some other work that's planned going to conflict with replacing this asset?  Several of these questions can't be answered by simply spitting out a list of asset IDs.  The maintenance planner will have to reference a diagram of the plant to answer several of these questions. This is precisely the idea behind Augmented Business Visualization. An Augmented Business Visualization (ABV) solution is one where your structured data (enterprise application data) and your unstructured data (documents, contracts, floor plans, designs, etc.) come together to allow you to make better decisions.  Essentially we're showing your business data into its context. AutoVue allows you to create ABV solutions by integrating your enterprise application with AutoVue’s hotspot framework. Hotspots can be defined for your document. Users can click these hotspots to trigger actions in your enterprise app. Similarly, the enterprise app can highlight the hotspots in your document based on its business data, creating a visual dashboard of your business data in the context of your document. ABV is not new. We introduced the hotspot framework in AutoVue 20.1 with text hotspots. Any text in a PDF or 2D CAD drawing could be turned into a hotspot. In 20.2 we have enhanced this to include 2 new types of hotspots: 3D and regional hotspots. 3D hotspots allow you to turn 3D parts into hotspots. Hotspots can be defined based on the attributes of the part, so you can create hotspots based on part numbers, material, date of delivery, etc.  Regional hotspots allow an administrator to define rectangular regions on any PDF, image, or 2D CAD drawing. This is perfect for cases where the document you’re using either doesn’t have text in it (a JPG or TIFF for example) or if you want to define hotspots that don’t correspond to the text in the document. There are lots of possible uses for AutoVue hotspots.  A great demonstration of how our hotspot capabilities can help add context to enterprise data in the Energy sector can be found in the following AutoVue movies: Maintenance Planning in the Energy Sector - Watch it Now Capital Construction Project Management in the Energy Sector  -  Watch it Now Commissioning and Handover Process for the Energy Sector  -  Watch it Now

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• Key Windows Phone Development Concepts

  - by Tim Murphy

  As I am doing more development in and out of the enterprise arena for Windows Phone I decide I would study for the 70-599 test.  I generally take certification tests as a way to force me to dig deeper into a technology.  Between the development and studying I decided it would be good to put a post together of key development features in Windows Phone 7 environment.  Contrary to popular belief the launch of Windows Phone 8 will not obsolete Windows Phone 7 development.  With the launch of 7.8 coming shortly and people who will remain on 7.X for the foreseeable future there are still consumers needing these apps so don’t throw out the baby with the bath water. PhoneApplicationService This is a class that every Windows Phone developer needs to become familiar with.  When it comes to application state this is your go to repository.  It also contains events that help with management of your application’s lifecycle.  You can access it like the following code sample. 1: PhoneApplicationService.Current.State["ValidUser"] = userResult; DeviceNetworkInformation This class allows you to determine the connectivity of the device and be notified when something changes with that connectivity.  If you are making web service calls you will want to check here before firing off. I have found that this class doesn’t actually work very well for determining if you have internet access.  You are better of using the following code where IsConnectedToInternet is an App level property. private void Application_Launching(object sender, LaunchingEventArgs e){ // Validate user access if (Microsoft.Phone.Net.NetworkInformation.NetworkInterface.NetworkInterfaceType != Microsoft.Phone.Net.NetworkInformation.NetworkInterfaceType.None) { IsConnectedToInternet = true; } else { IsConnectedToInternet = false; } NetworkChange.NetworkAddressChanged += new NetworkAddressChangedEventHandler(NetworkChange_NetworkAddressChanged);}void NetworkChange_NetworkAddressChanged(object sender, EventArgs e){ IsConnectedToInternet = (Microsoft.Phone.Net.NetworkInformation.NetworkInterface.NetworkInterfaceType != Microsoft.Phone.Net.NetworkInformation.NetworkInterfaceType.None);} Push Notification Push notification allows your application to receive notifications in a way that reduces the application’s power needs. This MSDN article is a good place to get the basics of push notification, but you can see the essential concept in the diagram below.  There are three types of push notification: toast, Tile and raw.  The first two work regardless of the state of the application where as raw messages are discarded if your application is not running.   Live Tiles Live tiles are one of the main differentiators of the Windows Phone platform.  They allow users to find information at a glance from their start screen without navigating into individual apps.  Knowing how to implement them can be a great boost to the attractiveness of your application. The simplest step-by-step explanation for creating live tiles is here. Local Database While your application really only has Isolated Storage as a data store there are some ways of giving you database functionality to develop against.  There are a number of open source ORM style solutions.  Probably the best and most native way I have found is to use LINQ to SQL.  It does take a significant amount of setup, but the ease of use once it is configured is worth the cost.  Rather than repeat the full concepts here I will point you to a post that I wrote previously. Tasks (Bing, Email) Leveraging built in features of the Windows Phone platform is an easy way to add functionality that would be expensive to develop on your own.  The classes that you need to make yourself familiar with are BingMapsDirectionsTask and EmailComposeTask.  This will allow your application to supply directions and give the user an email path to relay information to friends and associates. Event model Because of the ability for users to switch quickly to switch to other apps or the home screen is just one reason why knowing the Windows Phone event model is important.  You need to be able to save data so that if a user gets a phone call they can come back to exactly where they were in your application.  This means that you will need to handle such events as Launching, Activated, Deactivated and Closing at an application level.  You will probably also want to get familiar with the OnNavigatedTo and OnNavigatedFrom events at the page level.  These will give you an opportunity to save data as a user navigates through your app. Summary This is just a small portion of the concepts that you will use while building Windows Phone apps, but these are some of the most critical.  With the launch of Windows Phone 8 this list will probably expand.  Take the time to investigate these topics further and try them out in your apps. del.icio.us Tags: Windows Phone 7,Windows Phone,WP7,Software Development,70-599

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• Hopping/Tumbling Windows Could Introduce Latency.

  This is a pre-article to one I am going to be writing on adjusting an event’s time and duration to satisfy business process requirements but it is one that I think is really useful when understanding the way that Hopping/Tumbling windows work within StreamInsight.  A Tumbling window is just a special shortcut version of  a Hopping window where the width of the window is equal to the size of the hop Here is the simplest and often used definition for a Hopping Window.  You can find them all here public static CepWindowStream<CepWindow<TPayload>> HoppingWindow<TPayload>(     this CepStream<TPayload> source,     TimeSpan windowSize,     TimeSpan hopSize,     WindowInputPolicy inputPolicy,     HoppingWindowOutputPolicy outputPolicy )   And here is the definition for a Tumbling Window public static CepWindowStream<CepWindow<TPayload>> TumblingWindow<TPayload>(     this CepStream<TPayload> source,     TimeSpan windowSize,     WindowInputPolicy inputPolicy,     HoppingWindowOutputPolicy outputPolicy )   These methods allow you to group events into windows of a temporal size.  It is a really useful and simple feature in StreamInsight.  One of the downsides though is that the windows cannot be flushed until an event in a following window occurs.  This means that you will potentially never see some events or see them with a delay.  Let me explain. Remember that a stream is a potentially unbounded sequence of events. Events in StreamInsight are given a StartTime.  It is this StartTime that is used to calculate into which temporal window an event falls.  It is best practice to assign a timestamp from the source system and not one from the system clock on the processing server.  StreamInsight cannot know when a window is over.  It cannot tell whether you have received all events in the window or whether some events have been delayed which means that StreamInsight cannot flush the stream for you.   Imagine you have events with the following Timestamps 12:10:10 PM 12:10:20 PM 12:10:35 PM 12:10:45 PM 11:59:59 PM And imagine that you have defined a 1 minute Tumbling Window over this stream using the following syntax var HoppingStream = from shift in inputStream.TumblingWindow(TimeSpan.FromMinutes(1),HoppingWindowOutputPolicy.ClipToWindowEnd) select new WindowCountPayload { CountInWindow = (Int32)shift.Count() };   The events between 12:10:10 PM and 12:10:45 PM will not be seen until the event at 11:59:59 PM arrives.  This could be a real problem if you need to react to windows promptly This can always be worked around by using a different design pattern but a lot of the examples I see assume there is a constant, very frequent stream of events resulting in windows always being flushed. Further examples of using windowing in StreamInsight can be found here

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• When should I use a Process Model versus a Use Case?

  - by Dave Burke

  This Blog entry is a follow on to https://blogs.oracle.com/oum/entry/oum_is_business_process_and and addresses a question I sometimes get asked…..i.e. “when I am gathering requirements on a Project, should I use a Process Modeling approach, or should I use a Use Case approach?” Not surprisingly, the short answer is “it depends”! Let’s take a scenario where you are working on a Sales Force Automation project. We’ll call the process that is being implemented “Lead-to-Order”. I would typically think of this type of project as being “Process Centric”. In other words, the focus will be on orchestrating a series of human and system related tasks that ultimately deliver value to the business in a cost effective way. Put in even simpler terms……implement an automated pre-sales system. For this type of (Process Centric) project, requirements would typically be gathered through a series of Workshops where the focal point will be on creating, or confirming, the Future-State (To-Be) business process. If pre-defined “best-practice” business process models exist, then of course they could and should be used during the Workshops, but even in their absence, the focus of the Workshops will be to define the optimum series of Tasks, their connections, sequence, and dependencies that will ultimately reflect a business process that meets the needs of the business. Now let’s take another scenario. Assume you are working on a Content Management project that involves automating the creation and management of content for User Manuals, Web Sites, Social Media publications etc. Would you call this type of project “Process Centric”?.......well you could, but it might also fall into the category of complex configuration, plus some custom extensions to a standard software application (COTS). For this type of project it would certainly be worth considering using a Use Case approach in order to 1) understand the requirements, and 2) to capture the functional requirements of the custom extensions. At this point you might be asking “why couldn’t I use a Process Modeling approach for my Content Management project?” Well, of course you could, but you just need to think about which approach is the most effective. Start by analyzing the types of Tasks that will eventually be automated by the system, for example: Best Suited To? Task Name Process Model Use Case Notes Manage outbound calls Ö A series of linked human and system tasks for calling and following up with prospects Manage content revision Ö Updating the content on a website Update User Preferences Ö Updating a users display preferences Assign Lead Ö Reviewing a lead, then assigning it to a sales person Convert Lead to Quote Ö Updating the status of a lead, and then converting it to a sales order As you can see, it’s not an exact science, and either approach is viable for the Tasks listed above. However, where you have a series of interconnected Tasks or Activities, than when combined, deliver value to the business, then that would be a good indicator to lead with a Process Modeling approach. On the other hand, when the Tasks or Activities in question are more isolated and/or do not cross traditional departmental boundaries, then a Use Case approach might be worth considering. Now let’s take one final scenario….. As you captured the To-Be Process flows for the Sales Force automation project, you discover a “Gap” in terms of what the client requires, and what the standard COTS application can provide. Let’s assume that the only way forward is to develop a Custom Extension. This would now be a perfect opportunity to document the functional requirements (behind the Gap) using a Use Case approach. After all, we will be developing some new software, and one of the most effective ways to begin the Software Development Lifecycle is to follow a Use Case approach. As always, your comments are most welcome.

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• How to make this design closer to proper DDD?

  - by Seralize

  I've read about DDD for days now and need help with this sample design. All the rules of DDD make me very confused to how I'm supposed to build anything at all when domain objects are not allowed to show methods to the application layer; where else to orchestrate behaviour? Repositories are not allowed to be injected into entities and entities themselves must thus work on state. Then an entity needs to know something else from the domain, but other entity objects are not allowed to be injected either? Some of these things makes sense to me but some don't. I've yet to find good examples of how to build a whole feature as every example is about Orders and Products, repeating the other examples over and over. I learn best by reading examples and have tried to build a feature using the information I've gained about DDD this far. I need your help to point out what I do wrong and how to fix it, most preferably with code as "I would not recomment doing X and Y" is very hard to understand in a context where everything is just vaguely defined already. If I can't inject an entity into another it would be easier to see how to do it properly. In my example there are users and moderators. A moderator can ban users, but with a business rule: only 3 per day. I did an attempt at setting up a class diagram to show the relationships (code below): interface iUser { public function getUserId(); public function getUsername(); } class User implements iUser { protected $_id; protected $_username; public function __construct(UserId $user_id, Username $username) { $this->_id = $user_id; $this->_username = $username; } public function getUserId() { return $this->_id; } public function getUsername() { return $this->_username; } } class Moderator extends User { protected $_ban_count; protected $_last_ban_date; public function __construct(UserBanCount $ban_count, SimpleDate $last_ban_date) { $this->_ban_count = $ban_count; $this->_last_ban_date = $last_ban_date; } public function banUser(iUser &$user, iBannedUser &$banned_user) { if (! $this->_isAllowedToBan()) { throw new DomainException('You are not allowed to ban more users today.'); } if (date('d.m.Y') != $this->_last_ban_date->getValue()) { $this->_ban_count = 0; } $this->_ban_count++; $date_banned = date('d.m.Y'); $expiration_date = date('d.m.Y', strtotime('+1 week')); $banned_user->add($user->getUserId(), new SimpleDate($date_banned), new SimpleDate($expiration_date)); } protected function _isAllowedToBan() { if ($this->_ban_count >= 3 AND date('d.m.Y') == $this->_last_ban_date->getValue()) { return false; } return true; } } interface iBannedUser { public function add(UserId $user_id, SimpleDate $date_banned, SimpleDate $expiration_date); public function remove(); } class BannedUser implements iBannedUser { protected $_user_id; protected $_date_banned; protected $_expiration_date; public function __construct(UserId $user_id, SimpleDate $date_banned, SimpleDate $expiration_date) { $this->_user_id = $user_id; $this->_date_banned = $date_banned; $this->_expiration_date = $expiration_date; } public function add(UserId $user_id, SimpleDate $date_banned, SimpleDate $expiration_date) { $this->_user_id = $user_id; $this->_date_banned = $date_banned; $this->_expiration_date = $expiration_date; } public function remove() { $this->_user_id = ''; $this->_date_banned = ''; $this->_expiration_date = ''; } } // Gathers objects $user_repo = new UserRepository(); $evil_user = $user_repo->findById(123); $moderator_repo = new ModeratorRepository(); $moderator = $moderator_repo->findById(1337); $banned_user_factory = new BannedUserFactory(); $banned_user = $banned_user_factory->build(); // Performs ban $moderator->banUser($evil_user, $banned_user); // Saves objects to database $user_repo->store($evil_user); $moderator_repo->store($moderator); $banned_user_repo = new BannedUserRepository(); $banned_user_repo->store($banned_user); Should the User entitity have a 'is_banned' field which can be checked with $user->isBanned();? How to remove a ban? I have no idea.

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• Web optimization

  - by hmloo

  1. CSS Optimization Organize your CSS code Good CSS organization helps with future maintainability of the site, it helps you and your team member understand the CSS more quickly and jump to specific styles. Structure CSS code For small project, you can break your CSS code in separate blocks according to the structure of the page or page content. for example you can break your CSS document according the content of your web page(e.g. Header, Main Content, Footer) Structure CSS file For large project, you may feel having too much CSS code in one place, so it's the best to structure your CSS into more CSS files, and use a master style sheet to import these style sheets. this solution can not only organize style structure, but also reduce server request./*--------------Master style sheet--------------*/ @import "Reset.css"; @import "Structure.css"; @import "Typography.css"; @import "Forms.css"; Create index for your CSS Another important thing is to create index at the beginning of your CSS file, index can help you quickly understand the whole CSS structure./*---------------------------------------- 1. Header 2. Navigation 3. Main Content 4. Sidebar 5. Footer ------------------------------------------*/ Writing efficient CSS selectors keep in mind that browsers match CSS selectors from right to left and the order of efficiency for selectors 1. id (#myid) 2. class (.myclass) 3. tag (div, h1, p) 4. adjacent sibling (h1 + p) 5. child (ul > li) 6. descendent (li a) 7. universal (*) 8. attribute (a[rel="external"]) 9. pseudo-class and pseudo element (a:hover, li:first) the rightmost selector is called "key selector", so when you write your CSS code, you should choose more efficient key selector. Here are some best practice: Don't tag-qualify Never do this:div#myid div.myclass .myclass#myid IDs are unique, classes are more unique than a tag so they don't need a tag. Doing so makes the selector less efficient. Avoid overqualifying selectors for example#nav a is more efficient thanul#nav li a Don't repeat declarationExample: body {font-size:12px;}h1 {font-size:12px;font-weight:bold;} since h1 is already inherited from body, so you don't need to repeate atrribute. Using 0 instead of 0px Always using #selector { margin: 0; } There’s no need to include the px after 0, removing all those superfluous px can reduce the size of your CSS file. Group declaration Example: h1 { font-size: 16pt; } h1 { color: #fff; } h1 { font-family: Arial, sans-serif; } it’s much better to combine them:h1 { font-size: 16pt; color: #fff; font-family: Arial, sans-serif; } Group selectorsExample: h1 { color: #fff; font-family: Arial, sans-serif; } h2 { color: #fff; font-family: Arial, sans-serif; } it would be much better if setup as:h1, h2 { color: #fff; font-family: Arial, sans-serif; } Group attributeExample: h1 { color: #fff; font-family: Arial, sans-serif; } h2 { color: #fff; font-family: Arial, sans-serif; font-size: 16pt; } you can set different rules for specific elements after setting a rule for a grouph1, h2 { color: #fff; font-family: Arial, sans-serif; } h2 { font-size: 16pt; } Using Shorthand PropertiesExample: #selector { margin-top: 8px; margin-right: 4px; margin-bottom: 8px; margin-left: 4px; }Better: #selector { margin: 8px 4px 8px 4px; }Best: #selector { margin: 8px 4px; } a good diagram illustrated how shorthand declarations are interpreted depending on how many values are specified for margin and padding property. instead of using:#selector { background-image: url(”logo.png”); background-position: top left; background-repeat: no-repeat; } is used:#selector { background: url(logo.png) no-repeat top left; } 2. Image Optimization Image Optimizer Image Optimizer is a free Visual Studio2010 extension that optimizes PNG, GIF and JPG file sizes without quality loss. It uses SmushIt and PunyPNG for the optimization. Just right click on any folder or images in Solution Explorer and choose optimize images, then it will automatically optimize all PNG, GIF and JPEG files in that folder. CSS Image Sprites CSS Image Sprites are a way to combine a collection of images to a single image, then use CSS background-position property to shift the visible area to show the required image, many images can take a long time to load and generates multiple server requests, so Image Sprite can reduce the number of server requests and improve site performance. You can use many online tools to generate your image sprite and CSS, and you can also try the Sprite and Image Optimization framework released by The ASP.NET team.

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• Notes from AT&T ARO Session at Oredev 2013

  - by Geertjan

  The mobile internet is 12 times bigger than internet was 12 years ago. Explosive growth, faster networks, and more powerful devices. 85% of users prefer mobile apps, while 56% have problems. Almost 60% want less than 2 second mobile app startup. App with poor mobile experience results in not buying stuff, going to competitor, not liking your company. Battery life. Bad mobile app is worse than no app at all because it turns people away from brand, etc. Apps didn't exist 10 years ago, 72 billion dollars a year in 2013, 151 billion in 2017.Testing performance. Mobile is different than regular app. Need to fix issues before customers discover them. ARO is free and open source AT&T tool for identifying mobile app performance problems. Mobile data is different -- radio resource control state machine. Radio resource control -- radio from idle to continuous reception -- drains battery, sends data, packets coming through, after packets come through radio is still on which is tail time, after 10 seconds of no data coming through radio goes off. For example, YouTube, e.g., 10 to 15 seconds after every connection, can be huge drain on battery, app traffic triggers RRC state. Goal. Balance fast network connectivity against battery usage. ARO is free and open source and test any platform and won awards. How do I test my app? pcap or tcdump network. Native collector: Android and iOS. Android rooted device is needed. Test app on phone, background data, idle for ads and analytics. Graded against 25 best practices. See all the processes, all network traffic mapped to processes, stats about trace, can look just at your app, exlude Facebook, etc. Many tests conducted, e.g., file download, HTML (wrapped applications, e.g., cordova). Best Practices. Make stuff smaller. GZIP, smaller files, download faster, best for files larger than 800 bytes, minification -- remove tabs and commenting -- browser doesn't need that, just give processor what it needs remove wheat from chaff. Images -- make images smaller, 1024x1024 image for a checkmark, swish it, make it 33% smaller, ARO records the screen, probably could be 9 times smaller. Download less stuff. 17% of HTTP content on mobile is duplicate data because of caching, reloading from cache is 75% to 99% faster than downloading again, 75% possible savings which means app will start up faster because using cache -- everyone wants app starting up 2 seconds. Make fewer HTTP requests. Inline and combine CSS and JS when possible reduces the number of requests, spread images used often. Fewer connections. Faster and use less battery, for example, download an image every 60 secs, download an add every 60 seconds, send analytics every 60 seconds -- instead of that, use transaction manager, download everything at once, reduce amount of time connected to network by 40% also -- 80% of applications do NOT close connections when they are finished, e.g., download picture, 10 seconds later the radio turns off, if you do not explicitly close, eventually server closes, 38% more tail time, 40% less energy if you close connection right away, background data traffic is 27% of data and 55% of network time, this kills the battery. Look at redirection. Adds 200 to 600 ms on each connection, waterfall diagram to all the requests -- e.g., xyz.com redirect to www.xyz.com redirect to xyz.mobi to www.xyz.com, waterfall visualization of packets, minimize redirects but redirects are fine. HTML best practices. Order matters and hiding code (JS downloading blocks rendering, always do CSS before JS or JS asynchronously, CSS 'display:none' hides images from user but the browser downloads them which adds latency to application. Some apps turn on GPS for no reason. Tell network when down, but maybe some other app is using the radio at the same time. It's all about knowing best practices: everyone wins with ARO (carriers, e.g., AT&T, developers, customers). Faster apps, better battery usage, network traffic better, better app reviews, happier customers. MBTA app, referenced as an example.ARO is free, open source, can test all platforms.

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• Plagued by multithreaded bugs

  - by koncurrency

  On my new team that I manage, the majority of our code is platform, TCP socket, and http networking code. All C++. Most of it originated from other developers that have left the team. The current developers on the team are very smart, but mostly junior in terms of experience. Our biggest problem: multi-threaded concurrency bugs. Most of our class libraries are written to be asynchronous by use of some thread pool classes. Methods on the class libraries often enqueue long running taks onto the thread pool from one thread and then the callback methods of that class get invoked on a different thread. As a result, we have a lot of edge case bugs involving incorrect threading assumptions. This results in subtle bugs that go beyond just having critical sections and locks to guard against concurrency issues. What makes these problems even harder is that the attempts to fix are often incorrect. Some mistakes I've observed the team attempting (or within the legacy code itself) includes something like the following: Common mistake #1 - Fixing concurrency issue by just put a lock around the shared data, but forgetting about what happens when methods don't get called in an expected order. Here's a very simple example: void Foo::OnHttpRequestComplete(statuscode status) { m_pBar->DoSomethingImportant(status); } void Foo::Shutdown() { m_pBar->Cleanup(); delete m_pBar; m_pBar=nullptr; } So now we have a bug in which Shutdown could get called while OnHttpNetworkRequestComplete is occuring on. A tester finds the bug, captures the crash dump, and assigns the bug to a developer. He in turn fixes the bug like this. void Foo::OnHttpRequestComplete(statuscode status) { AutoLock lock(m_cs); m_pBar->DoSomethingImportant(status); } void Foo::Shutdown() { AutoLock lock(m_cs); m_pBar->Cleanup(); delete m_pBar; m_pBar=nullptr; } The above fix looks good until you realize there's an even more subtle edge case. What happens if Shutdown gets called before OnHttpRequestComplete gets called back? The real world examples my team has are even more complex, and the edge cases are even harder to spot during the code review process. Common Mistake #2 - fixing deadlock issues by blindly exiting the lock, wait for the other thread to finish, then re-enter the lock - but without handling the case that the object just got updated by the other thread! Common Mistake #3 - Even though the objects are reference counted, the shutdown sequence "releases" it's pointer. But forgets to wait for the thread that is still running to release it's instance. As such, components are shutdown cleanly, then spurious or late callbacks are invoked on an object in an state not expecting any more calls. There are other edge cases, but the bottom line is this: Multithreaded programming is just plain hard, even for smart people. As I catch these mistakes, I spend time discussing the errors with each developer on developing a more appropriate fix. But I suspect they are often confused on how to solve each issue because of the enormous amount of legacy code that the "right" fix will involve touching. We're going to be shipping soon, and I'm sure the patches we're applying will hold for the upcoming release. Afterwards, we're going to have some time to improve the code base and refactor where needed. We won't have time to just re-write everything. And the majority of the code isn't all that bad. But I'm looking to refactor code such that threading issues can be avoided altogether. One approach I am considering is this. For each significant platform feature, have a dedicated single thread where all events and network callbacks get marshalled onto. Similar to COM apartment threading in Windows with use of a message loop. Long blocking operations could still get dispatched to a work pool thread, but the completion callback is invoked on on the component's thread. Components could possibly even share the same thread. Then all the class libraries running inside the thread can be written under the assumption of a single threaded world. Before I go down that path, I am also very interested if there are other standard techniques or design patterns for dealing with multithreaded issues. And I have to emphasize - something beyond a book that describes the basics of mutexes and semaphores. What do you think? I am also interested in any other approaches to take towards a refactoring process. Including any of the following: Literature or papers on design patterns around threads. Something beyond an introduction to mutexes and semaphores. We don't need massive parallelism either, just ways to design an object model so as to handle asynchronous events from other threads correctly. Ways to diagram the threading of various components, so that it will be easy to study and evolve solutions for. (That is, a UML equivalent for discussing threads across objects and classes) Educating your development team on the issues with multithreaded code. What would you do?

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• Box2d: Set active and inactive

  - by Rosarch

  I'm writing an XNA game in C# using the XNA port of Box2d - Box2dx. Entities like trees or zombies are represented as GameObjects. GameObjectManager adds and removes them from the game world: /// <summary> /// Does the work of removing the GameObject. /// </summary> /// <param name="controller">The GameObject to be removed.</param> private void removeGameObjectFromWorld(GameObjectController controller) { controllers.Remove(controller); worldState.Models.Remove(controller.Model); controller.Model.Body.SetActive(false); } public void addGameObjectToWorld(GameObjectController controller) { controllers.Add(controller); worldState.Models.Add(controller.Model); controller.Model.Body.SetActive(true); } controllers is a collection of GameObjectController instances. worldState.Models is a collection of GameObjectModel instances. When I remove GameObjects from Box2d this way, this method gets called: void IContactListener.EndContact(Contact contact) { GameObjectController collider1 = worldQueryUtils.gameObjectOfBody(contact.GetFixtureA().GetBody()); GameObjectController collider2 = worldQueryUtils.gameObjectOfBody(contact.GetFixtureB().GetBody()); collisionRecorder.removeCollision(collider1, collider2); } worldQueryUtils: // this could be cached if we know bodies never change public GameObjectController gameObjectOfBody(Body body) { return worldQueryEngine.GameObjectsForPredicate(x => x.Model.Body == body).Single(); } This method throws an error: System.InvalidOperationException was unhandled Message="Sequence contains no elements" Source="System.Core" StackTrace: at System.Linq.Enumerable.Single[TSource](IEnumerable`1 source) at etc Why is this happening? What can I do to avoid it? This method has been called many times before the body.SetActive() was called. I feel that this may be messing it up.

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• pylucene: install error

  - by Pradeep

  I am trying to install Pylucene (pylucene-3.3-3-src.tar.gz) on my ubuntu linux 11.10. I have python 2.7.2. I was able to compile JCC (I think) because I didnt see any error when I installed it. When I tried to install Pylucene I get the following error. Can someone help? Thanks. ICU not installed /usr/bin/python -m jcc --shared --jar lucene-java-3.3/lucene/build/lucene-core-3.3.jar --jar lucene-java-3.3/lucene/build/contrib/analyzers/common/lucene-analyzers-3.3.jar --jar lucene-java-3.3/lucene/build/contrib/memory/lucene-memory-3.3.jar --jar lucene-java-3.3/lucene/build/contrib/highlighter/lucene-highlighter-3.3.jar --jar build/jar/extensions.jar --jar lucene-java-3.3/lucene/build/contrib/queries/lucene-queries-3.3.jar --jar lucene-java-3.3/lucene/build/contrib/grouping/lucene-grouping-3.3.jar --package java.lang java.lang.System java.lang.Runtime --package java.util java.util.Arrays java.util.HashMap java.util.HashSet java.text.SimpleDateFormat java.text.DecimalFormat java.text.Collator --package java.util.regex --package java.io java.io.StringReader java.io.InputStreamReader java.io.FileInputStream --exclude org.apache.lucene.queryParser.Token --exclude org.apache.lucene.queryParser.TokenMgrError --exclude org.apache.lucene.queryParser.QueryParserTokenManager --exclude org.apache.lucene.queryParser.ParseException --exclude org.apache.lucene.search.regex.JakartaRegexpCapabilities --exclude org.apache.regexp.RegexpTunnel --exclude org.apache.lucene.analysis.cn.smart.AnalyzerProfile --python lucene --mapping org.apache.lucene.document.Document 'get:(Ljava/lang/String;)Ljava/lang/String;' --mapping java.util.Properties 'getProperty:(Ljava/lang/String;)Ljava/lang/String;' --sequence java.util.AbstractList 'size:()I' 'get:(I)Ljava/lang/Object;' --rename org.apache.lucene.search.highlight.SpanScorer=HighlighterSpanScorer --version 3.3 --module python/collections.py --module python/ICUNormalizer2Filter.py --module python/ICUFoldingFilter.py --module python/ICUTransformFilter.py --files 3 --build /usr/bin/python: No module named jcc make: *** [compile] Error 1 Here is my Makefile configuration which I uncommented PREFIX_PYTHON=/usr ANT=ant PYTHON=$(PREFIX_PYTHON)/bin/python JCC=$(PYTHON) -m jcc --shared NUM_FILES=3

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• SSRS 2005 - Cascading parameters and default value update problem

  - by sHr0oMaN

  I have a report with cascading parameters. The first parameter is Finanical Period Type, being either Month or Week. The second parameter is a list of either financial months or weeks depending on what was selected for the first parameter. This all works well and selecting a series of different Financial Period Types in sequence correctly updates the second parameter's values. However I now wish to add a default value for the second parameter, which is once again dependent on the first parameter. So I've added an additional field to the dataset populating the second parameter called DefaultPeriod and set the second parameter's default value to be retrieved from the above field. The first time I select the Financial Period Type, the default is correctly set. However changing the Financial Period Type results in an updated list for the second parameter, but the default is incorrect. It remains set to the original default value, even thought the dataset has been refresh and the DefaultPeriod field is correct. This is both an issue in the IDE and on the Report Manager site.

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• What is wrong with this solution? (Perm-Missing-Elem codility test)

  - by user2956907

  I have started playing with codility and came across this problem: A zero-indexed array A consisting of N different integers is given. The array contains integers in the range [1..(N + 1)], which means that exactly one element is missing. Your goal is to find that missing element. Write a function: int solution(int A[], int N); that, given a zero-indexed array A, returns the value of the missing element. For example, given array A such that: A[0] = 2 A[1] = 3 A[2] = 1 A[3] = 5 the function should return 4, as it is the missing element. Assume that: N is an integer within the range [0..100,000]; the elements of A are all distinct; each element of array A is an integer within the range [1..(N + 1)]. Complexity: expected worst-case time complexity is O(N); expected worst-case space complexity is O(1), beyond input storage (not counting the storage required for input arguments). I have submitted the following solution (in PHP): function solution($A) { $nr = count($A); $totalSum = (($nr+1)*($nr+2))/2; $arrSum = array_sum($A); return ($totalSum-$arrSum); } which gave me a score of 66 of 100, because it was failing the test involving large arrays: "large_range range sequence, length = ~100,000" with the result: RUNTIME ERROR tested program terminated unexpectedly stdout: Invalid result type, int expected. I tested locally with an array of 100.000 elements, and it worked without any problems. So, what seems to be the problem with my code and what kind of test cases did codility use to return "Invalid result type, int expected"?

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• fresh installation of PGF/TikZ crashes, why?

  - by Vincenzo

  I have a clean CentOS 5.5 machine with tetex installed. Next, I installed PGF/TikZ: wget http://media.texample.net/pgf/builds/pgfCVS2010-06-02_TDS.zip unzip pgfCVS2010-06-02_TDS.zip \cp -r tex /usr/share/texmf texhash I'm trying to compile a simple document and this is what I'm getting: $ latex test.tex This is pdfeTeX, Version 3.141592-1.21a-2.2 (Web2C 7.5.4) entering extended mode (./test.tex LaTeX2e <2003/12/01> .. skipped .. (/usr/share/texmf/tex/latex/pgf/frontendlayer/tikz.sty (/usr/share/texmf/tex/latex/pgf/pgf.sty (/usr/share/texmf/tex/latex/graphics/graphicx.sty (/usr/share/texmf/tex/latex/graphics/graphics.sty (/usr/share/texmf/tex/latex/graphics/trig.sty) (/usr/share/texmf/tex/latex/graphics/graphics.cfg)))) (/usr/share/texmf/tex/latex/pgf/utilities/pgffor.sty (/usr/share/texmf/tex/latex/pgf/utilities/pgfrcs.sty (/usr/share/texmf/tex/generic/pgf/utilities/pgfutil-common.tex) (/usr/share/texmf/tex/generic/pgf/utilities/pgfutil-latex.def) (/usr/share/texmf/tex/generic/pgf/utilities/pgfrcs.code.tex)) (/usr/share/texmf/tex/latex/pgf/utilities/pgfkeys.sty (/usr/share/texmf/tex/generic/pgf/utilities/pgfkeys.code.tex (/usr/share/texmf/tex/generic/pgf/utilities/pgfkeysfiltered.code.tex))) (/usr/share/texmf/tex/generic/pgf/utilities/pgffor.code.tex)) (/usr/share/texmf/tex/generic/pgf/frontendlayer/tikz/tikz.code.tex (/usr/share/texmf/tex/generic/pgf/libraries/pgflibraryplothandlers.code.tex ! Undefined control sequence. \pgfsetplottension ...ttension {\pgf@sys@tonumber \pgf@x } l.104 \pgfsetplottension{0.5} ? I failed to find any clues in the net about this problem. On other servers I don't such a problem. Could anyone help please? Thanks! ps. Btw, I tried another build of PGF/TikZ, the older one, no luck :(

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• Changing the Android emulator locale automatically

  - by Christopher

  For automated testing (using Hudson) I have a script that generates a bunch of emulators for many combinations of Android OS version, screen resolution, screen density and language. This works fine, except for the language part. I need to find a way to change the Android system locale automatically. Here's some approaches I can think of, in order of preference: Extracting/editing/repacking a QEMU image directly before starting the emulator Running some sort of system-locale-changing APK on the emulator after startup Changing the locale settings on the emulator filesystem after startup Changing the locale settings in some SQLite DB on the emulator after startup Running a key sequence (via the emulator's telnet interface) that would open the settings app and change the locale Manually starting the emulator for each platform version, changing the locale by hand in the settings, saving it and archiving the images for later deployment Any ideas whether this can be done, either via the above methods or otherwise? Do you know where locale settings are persisted to/read from by the system? Solution: Thanks to dtmilano's info about the relevant properties, and some further investigation on my part, I came up with a solution even better and simpler simpler than all the ideas above! I have updated the answer below with the details.

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• Wix - Upgrade always runs older installer msi and fails in trying to read old msi

  - by rkhj

  I'm having a problem though with the Windows caching of the installer. I'm trying to do an upgrade and each time the Windows installer is launching the installer of the older version. And when I do the upgrade it is complaining about problems with reading the older version's msi file (because its not in the same directory anymore). I did change the UpgradeCode and the ProductCode but kept the PackageCode the same. I also have different ProductVersion codes (2.2.3 vs 2.3.0). Here's a sample of my code: <Upgrade Id="$(var.UpgradeCode)"> <UpgradeVersion Property="OLDAPPFOUND" IncludeMinimum="yes" Minimum="$(var.RTMProductVersion)" IncludeMaximum="no" Maximum="$(var.ProductVersion)"/> <UpgradeVersion Property="NEWAPPFOUND" IncludeMinimum="no" Minimum="$(var.ProductVersion)" OnlyDetect="yes"/> </Upgrade> This is the Install Sequence: <InstallExecuteSequence> <Custom Action='SetUpgradeParams' After='InstallFiles'>Installed AND NEWAPPFOUND</Custom> <Custom Action='Upgrade' After='SetUpgradeParams'>Installed AND NEWAPPFOUND</Custom> </InstallExecuteSequence> The error I am getting is: A network error occurred while attempting to read from the file: Thanks,

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• Problem retrieving Strings from varbinary columns using HIbernate and MySQL

  - by user303396

  Hello, Here's my scenario. I save a bunch of Strings containing asian characters in MySQL using Hibernate. These strings are written in varbinary columns. Everything works fine during the saving operation. The DB contains the correct values (sequence of bytes). If I query (again using Hibernate) for the Strings that I saved I get the correct results. But when Hibernate fills the entity to which the Strings belong with the values from the DB I get different values then the ones I used in the query that retrieved them. Instead of receiving the correct values I receive a bunch of FFFD replacement characters. For example: if I store "??" in the DB and then I query for it, the resulting String will be \uFFFD\uFFFD\uFFFD\uFFFD\uFFFD\uFFFD. the DB connection has the following parameters set useUnicode=true&characterEncoding=UTF-8, I've tried using the true UTF-8 configurations for Hibernate but that didn't solve the problem What am I missing? Any suggestions? Thanks

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