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  • Architecture strategies for a complex competition scoring system

    - by mikewassmer
    Competition description: There are about 10 teams competing against each other over a 6-week period. Each team's total score (out of a 1000 total available points) is based on the total of its scores in about 25,000 different scoring elements. Most scoring elements are worth a small fraction of a point and there will about 10 X 25,000 = 250,000 total raw input data points. The points for some scoring elements are awarded at frequent regular time intervals during the competition. The points for other scoring elements are awarded at either irregular time intervals or at just one moment in time. There are about 20 different types of scoring elements. Each of the 20 types of scoring elements has a different set of inputs, a different algorithm for calculating the earned score from the raw inputs, and a different number of total available points. The simplest algorithms require one input and one simple calculation. The most complex algorithms consist of hundreds or thousands of raw inputs and a more complicated calculation. Some types of raw inputs are automatically generated. Other types of raw inputs are manually entered. All raw inputs are subject to possible manual retroactive adjustments by competition officials. Primary requirements: The scoring system UI for competitors and other competition followers will show current and historical total team scores, team standings, team scores by scoring element, raw input data (at several levels of aggregation, e.g. daily, weekly, etc.), and other metrics. There will be charts, tables, and other widgets for displaying historical raw data inputs and scores. There will be a quasi-real-time dashboard that will show current scores and raw data inputs. Aggregate scores should be updated/refreshed whenever new raw data inputs arrive or existing raw data inputs are adjusted. There will be a "scorekeeper UI" for manually entering new inputs, manually adjusting existing inputs, and manually adjusting calculated scores. Decisions: Should the scoring calculations be performed on the database layer (T-SQL/SQL Server, in my case) or on the application layer (C#/ASP.NET MVC, in my case)? What are some recommended approaches for calculating updated total team scores whenever new raw inputs arrives? Calculating each of the teams' total scores from scratch every time a new input arrives will probably slow the system to a crawl. I've considered some kind of "diff" approach, but that approach may pose problems for ad-hoc queries and some aggegates. I'm trying draw some sports analogies, but it's tough because most games consist of no more than 20 or 30 scoring elements per game (I'm thinking of a high-scoring baseball game; football and soccer have fewer scoring events per game). Perhaps a financial balance sheet analogy makes more sense because financial "bottom line" calcs may be calculated from 250,000 or more transactions. Should I be making heavy use of caching for this application? Are there any obvious approaches or similar case studies that I may be overlooking?

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  • Oracle Products Reflect Key Trends Shaping Enterprise 2.0

    - by kellsey.ruppel(at)oracle.com
    Following up on his predictions for 2011, we asked Enterprise 2.0 veteran Andy MacMillan to map out the ways Oracle solutions are at the forefront of industry trends--and how Oracle customers can benefit in the coming year. 1. Increase organizational awareness | Oracle WebCenter Suite Oracle WebCenter Suite provides a unique set of capabilities to drive organizational awareness. In particular, the expansive activity graph connects users directly to key enterprise applications, activities, and interests. In this way, applicable and critical business information is automatically and immediately visible--in the context of key tasks--via real-time dashboards and comprehensive reporting. Oracle WebCenter Suite also integrates key E2.0 services, such as blogs, wikis, and RSS feeds, into critical business processes, including back-office systems of records such as ERP and CRM systems. 2. Drive online customer engagement | Oracle Real-Time Decisions With more and more business being conducted on the Web, driving increased online customer engagement becomes a critical key to success. This effort is usually spearheaded by an increasingly important executive role, the Head of Online, who usually reports directly to the CMO. To help manage the Web experience online, Oracle solutions are driving a new kind of intelligent social commerce by combining Oracle Universal Content Management, Oracle WebCenter Services, and Oracle Real-Time Decisions with leading e-commerce and product recommendations. Oracle Real-Time Decisions provides multichannel recommendations for content, products, and services--including seamless integration across Web, mobile, and social channels. The result: happier customers, increased customer acquisition and retention, and improved critical success metrics such as shopping cart abandonment. 3. Easily build composite applications | Oracle Application Development Framework Thanks to the shared user experience strategy across Oracle Fusion Middleware, Oracle Fusion Applications and many other Oracle Applications, customers can easily create real, customer-specific composite applications using Oracle WebCenter Suite and Oracle Application Development Framework. Oracle Application Development Framework components provide modular user interface components that can build rich, social composite applications. In addition, a broad set of components spanning BPM, SOA, ECM, and beyond can be quickly and easily incorporated into composite applications. 4. Integrate records management into a global content platform | Oracle Enterprise Content Management 11g Oracle Enterprise Content Management 11g provides leading records management capabilities as part of a unified ECM platform for managing records, documents, Web content, digital assets, enterprise imaging, and application imaging. This unique strategy provides comprehensive records management in a consistent, cost-effective way, and enables organizations to consolidate ECM repositories and connect ECM to critical business applications. 5. Achieve ECM at extreme scale | Oracle WebLogic Server and Oracle Exadata To support the high-performance demands of a unified and rationalized content platform, Oracle has pioneered highly scalable and high-performing ECM infrastructures. Two innovations in particular helped make this happen. The core ECM platform itself moved to an Enterprise Java architecture, so organizations can now use Oracle WebLogic Server for enhanced scalability and manageability. Oracle Enterprise Content Management 11g can leverage Oracle Exadata for extreme performance and scale. Likewise, Oracle Exalogic--Oracle's foundation for cloud computing--enables extreme performance for processor-intensive capabilities such as content conversion or dynamic Web page delivery. Learn more about Oracle's Enterprise 2.0 solutions.

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  • My Take on Hadoop World 2011

    - by Jean-Pierre Dijcks
    I’m sure some of you have read pieces about Hadoop World and I did see some headlines which were somewhat, shall we say, interesting? I thought the keynote by Larry Feinsmith of JP Morgan Chase & Co was one of the highlights of the conference for me. The reason was very simple, he addressed some real use cases outside of internet and ad platforms. The following are my notes, since the keynote was recorded I presume you can go and look at Hadoopworld.com at some point… On the use cases that were mentioned: ETL – how can I do complex data transformation at scale Doing Basel III liquidity analysis Private banking – transaction filtering to feed [relational] data marts Common Data Platform – a place to keep data that is (or will be) valuable some day, to someone, somewhere 360 Degree view of customers – become pro-active and look at events across lines of business. For example make sure the mortgage folks know about direct deposits being stopped into an account and ensure the bank is pro-active to service the customer Treasury and Security – Global Payment Hub [I think this is really consolidation of data to cross reference activity across business and geographies] Data Mining Bypass data engineering [I interpret this as running a lot of a large data set rather than on samples] Fraud prevention – work on event triggers, say a number of failed log-ins to the website. When they occur grab web logs, firewall logs and rules and start to figure out who is trying to log in. Is this me, who forget his password, or is it someone in some other country trying to guess passwords Trade quality analysis – do a batch analysis or all trades done and run them through an analysis or comparison pipeline One of the key requests – if you can say it like that – was for vendors and entrepreneurs to make sure that new tools work with existing tools. JPMC has a large footprint of BI Tools and Big Data reporting and tools should work with those tools, rather than be separate. Security and Entitlement – how to protect data within a large cluster from unwanted snooping was another topic that came up. I thought his Elephant ears graph was interesting (couldn’t actually read the points on it, but the concept certainly made some sense) and it was interesting – when asked to show hands – how the audience did not (!) think that RDBMS and Hadoop technology would overlap completely within a few years. Another interesting session was the session from Disney discussing how Disney is building a DaaS (Data as a Service) platform and how Hadoop processing capabilities are mixed with Database technologies. I thought this one of the best sessions I have seen in a long time. It discussed real use case, where problems existed, how they were solved and how Disney planned some of it. The planning focused on three things/phases: Determine the Strategy – Design a platform and evangelize this within the organization Focus on the people – Hire key people, grow and train the staff (and do not overload what you have with new things on top of their day-to-day job), leverage a partner with experience Work on Execution of the strategy – Implement the platform Hadoop next to the other technologies and work toward the DaaS platform This kind of fitted with some of the Linked-In comments, best summarized in “Think Platform – Think Hadoop”. In other words [my interpretation], step back and engineer a platform (like DaaS in the Disney example), then layer the rest of the solutions on top of this platform. One general observation, I got the impression that we have knowledge gaps left and right. On the one hand are people looking for more information and details on the Hadoop tools and languages. On the other I got the impression that the capabilities of today’s relational databases are underestimated. Mostly in terms of data volumes and parallel processing capabilities or things like commodity hardware scale-out models. All in all I liked this conference, it was great to chat with a wide range of people on Oracle big data, on big data, on use cases and all sorts of other stuff. Just hope they get a set of bigger rooms next time… and yes, I hope I’m going to be back next year!

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  • SQL Server 2008 Compression

    - by Peter Larsson
    Hi! Today I am going to talk about compression in SQL Server 2008. The data warehouse I currently design and develop holds historical data back to 1973. The data warehouse will have an other blog post laster due to it's complexity. However, the server has 60GB of memory (of which 48 is dedicated to SQL Server service), so all data didn't fit in memory and the SAN is not the fastest one around. So I decided to give compression a go, since we use Enterprise Edition anyway. This is the code I use to compress all tables with PAGE compression. DECLARE @SQL VARCHAR(MAX)   DECLARE curTables CURSOR FOR             SELECT 'ALTER TABLE ' + QUOTENAME(OBJECT_SCHEMA_NAME(object_id))                     + '.' + QUOTENAME(OBJECT_NAME(object_id))                     + ' REBUILD PARTITION = ALL WITH (DATA_COMPRESSION = PAGE)'             FROM    sys.tables   OPEN    curTables   FETCH   NEXT FROM    curTables INTO    @SQL   WHILE @@FETCH_STATUS = 0     BEGIN         IF @SQL IS NOT NULL             RAISERROR(@SQL, 10, 1) WITH NOWAIT           FETCH   NEXT         FROM    curTables         INTO    @SQL     END   CLOSE       curTables DEALLOCATE  curTables Copy and paste the result to a new code window and execute the statements. One thing I noticed when doing this, is that the database grows with the same size as the table. If the database cannot grow this size, the operation fails. For me, I first ended up with orphaned connection. Not good. And this is the code I use to create the index compression statements DECLARE @SQL VARCHAR(MAX)   DECLARE curIndexes CURSOR FOR             SELECT      'ALTER INDEX ' + QUOTENAME(name)                         + ' ON '                         + QUOTENAME(OBJECT_SCHEMA_NAME(object_id))                         + '.'                         + QUOTENAME(OBJECT_NAME(object_id))                         + ' REBUILD PARTITION = ALL WITH (FILLFACTOR = 100, DATA_COMPRESSION = PAGE)'             FROM        sys.indexes             WHERE       OBJECTPROPERTY(object_id, 'IsMSShipped') = 0                         AND OBJECTPROPERTY(object_id, 'IsTable') = 1             ORDER BY    CASE type_desc                             WHEN 'CLUSTERED' THEN 1                             ELSE 2                         END   OPEN    curIndexes   FETCH   NEXT FROM    curIndexes INTO    @SQL   WHILE @@FETCH_STATUS = 0     BEGIN         IF @SQL IS NOT NULL             RAISERROR(@SQL, 10, 1) WITH NOWAIT           FETCH   NEXT         FROM    curIndexes         INTO    @SQL     END   CLOSE       curIndexes DEALLOCATE  curIndexes When this was done, I noticed that the 90GB database now only was 17GB. And most important, complete database now could reside in memory! After this I took care of the administrative tasks, backups. Here I copied the code from Management Studio because I didn't want to give too much time for this. The code looks like (notice the compression option). BACKUP DATABASE [Yoda] TO              DISK = N'D:\Fileshare\Backup\Yoda.bak' WITH            NOFORMAT,                 INIT,                 NAME = N'Yoda - Full Database Backup',                 SKIP,                 NOREWIND,                 NOUNLOAD,                 COMPRESSION,                 STATS = 10,                 CHECKSUM GO   DECLARE @BackupSetID INT   SELECT  @BackupSetID = Position FROM    msdb..backupset WHERE   database_name = N'Yoda'         AND backup_set_id =(SELECT MAX(backup_set_id) FROM msdb..backupset WHERE database_name = N'Yoda')   IF @BackupSetID IS NULL     RAISERROR(N'Verify failed. Backup information for database ''Yoda'' not found.', 16, 1)   RESTORE VERIFYONLY FROM    DISK = N'D:\Fileshare\Backup\Yoda.bak' WITH    FILE = @BackupSetID,         NOUNLOAD,         NOREWIND GO After running the backup, the file size was even more reduced due to the zip-like compression algorithm used in SQL Server 2008. The file size? Only 9 GB. //Peso

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  • Infinite detail inside Perlin noise procedural mapping

    - by Dave Jellison
    I am very new to game development but I was able to scour the internet to figure out Perlin noise enough to implement a very simple 2D tile infinite procedural world. Here's the question and it's more conceptual than code-based in answer, I think. I understand the concept of "I plug in (x, y) and get back from Perlin noise p" (I'll call it p). P will always be the same value for the same (x, y) (as long as the Perlin algorithm parameters haven't changed, like altering number of octaves, et cetera). What I want to do is be able to zoom into a square and be able to generate smaller squares inside of the already generated overhead tile of terrain. Let's say I have a jungle tile for overhead terrain but I want to zoom in and maybe see a small river tile that would only be a creek and not large enough to be a full "big tile" of water in the overhead. Of course, I want the same net effect as a Perlin equation inside a Perlin equation if that makes sense? (aka. I want two people playing the game with the same settings to get the same terrain and details every time). I can conceptually wrap my head around the large tile being based on an "zoomed out" coordinate leaving enough room to drill into but this approach doesn't make sense in my head (maybe I'm wrong). I'm guessing with this approach my overhead terrain would lose all of the cohesiveness delivered by the Perlin. Imagine I calculate (0, 0) as overhead tile 1 and then to the east of that I plug in (50, 0). OK, great, I now have 49 pixels of detail I could then "drill down" into. The issue I have in my head with this approach (without attempting it) is that there's no guarantee from my Perlin noise that (0,0) would be a good neighbor to (50,0) as they could have wildly different "elevations" or p/resultant values returning from the Perlin equation when I generate the overhead map. I think I can conceive of using the Perlin noise for the overhead tile to then reuse the p value as a seed for the "detail" level of noise once I zoom in. That would ensure my detail Perlin is always the same configuration for (0,0), (1,0), etc. ad nauseam but I'm not sure if there are better approaches out there or if this is a sound approach at all.

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  • Big Data – Operational Databases Supporting Big Data – Key-Value Pair Databases and Document Databases – Day 13 of 21

    - by Pinal Dave
    In yesterday’s blog post we learned the importance of the Relational Database and NoSQL database in the Big Data Story. In this article we will understand the role of Key-Value Pair Databases and Document Databases Supporting Big Data Story. Now we will see a few of the examples of the operational databases. Relational Databases (Yesterday’s post) NoSQL Databases (Yesterday’s post) Key-Value Pair Databases (This post) Document Databases (This post) Columnar Databases (Tomorrow’s post) Graph Databases (Tomorrow’s post) Spatial Databases (Tomorrow’s post) Key Value Pair Databases Key Value Pair Databases are also known as KVP databases. A key is a field name and attribute, an identifier. The content of that field is its value, the data that is being identified and stored. They have a very simple implementation of NoSQL database concepts. They do not have schema hence they are very flexible as well as scalable. The disadvantages of Key Value Pair (KVP) database are that they do not follow ACID (Atomicity, Consistency, Isolation, Durability) properties. Additionally, it will require data architects to plan for data placement, replication as well as high availability. In KVP databases the data is stored as strings. Here is a simple example of how Key Value Database will look like: Key Value Name Pinal Dave Color Blue Twitter @pinaldave Name Nupur Dave Movie The Hero As the number of users grow in Key Value Pair databases it starts getting difficult to manage the entire database. As there is no specific schema or rules associated with the database, there are chances that database grows exponentially as well. It is very crucial to select the right Key Value Pair Database which offers an additional set of tools to manage the data and provides finer control over various business aspects of the same. Riak Rick is one of the most popular Key Value Database. It is known for its scalability and performance in high volume and velocity database. Additionally, it implements a mechanism for collection key and values which further helps to build manageable system. We will further discuss Riak in future blog posts. Key Value Databases are a good choice for social media, communities, caching layers for connecting other databases. In simpler words, whenever we required flexibility of the data storage keeping scalability in mind – KVP databases are good options to consider. Document Database There are two different kinds of document databases. 1) Full document Content (web pages, word docs etc) and 2) Storing Document Components for storage. The second types of the document database we are talking about over here. They use Javascript Object Notation (JSON) and Binary JSON for the structure of the documents. JSON is very easy to understand language and it is very easy to write for applications. There are two major structures of JSON used for Document Database – 1) Name Value Pairs and 2) Ordered List. MongoDB and CouchDB are two of the most popular Open Source NonRelational Document Database. MongoDB MongoDB databases are called collections. Each collection is build of documents and each document is composed of fields. MongoDB collections can be indexed for optimal performance. MongoDB ecosystem is highly available, supports query services as well as MapReduce. It is often used in high volume content management system. CouchDB CouchDB databases are composed of documents which consists fields and attachments (known as description). It supports ACID properties. The main attraction points of CouchDB are that it will continue to operate even though network connectivity is sketchy. Due to this nature CouchDB prefers local data storage. Document Database is a good choice of the database when users have to generate dynamic reports from elements which are changing very frequently. A good example of document usages is in real time analytics in social networking or content management system. Tomorrow In tomorrow’s blog post we will discuss about various other Operational Databases supporting 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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  • Is commented out code really always bad?

    - by nikie
    Practically every text on code quality I've read agrees that commented out code is a bad thing. The usual example is that someone changed a line of code and left the old line there as a comment, apparently to confuse people who read the code later on. Of course, that's a bad thing. But I often find myself leaving commented out code in another situation: I write a computational-geometry or image processing algorithm. To understand this kind of code, and to find potential bugs in it, it's often very helpful to display intermediate results (e.g. draw a set of points to the screen or save a bitmap file). Looking at these values in the debugger usually means looking at a wall of numbers (coordinates, raw pixel values). Not very helpful. Writing a debugger visualizer every time would be overkill. I don't want to leave the visualization code in the final product (it hurts performance, and usually just confuses the end user), but I don't want to loose it, either. In C++, I can use #ifdef to conditionally compile that code, but I don't see much differnce between this: /* // Debug Visualization: draw set of found interest points for (int i=0; i<count; i++) DrawBox(pts[i].X, pts[i].Y, 5,5); */ and this: #ifdef DEBUG_VISUALIZATION_DRAW_INTEREST_POINTS for (int i=0; i<count; i++) DrawBox(pts[i].X, pts[i].Y, 5,5); #endif So, most of the time, I just leave the visualization code commented out, with a comment saying what is being visualized. When I read the code a year later, I'm usually happy I can just uncomment the visualization code and literally "see what's going on". Should I feel bad about that? Why? Is there a superior solution? Update: S. Lott asks in a comment Are you somehow "over-generalizing" all commented code to include debugging as well as senseless, obsolete code? Why are you making that overly-generalized conclusion? I recently read Robert Glass' "Clean Code", which says: Few practices are as odious as commenting-out code. Don't do this!. I've looked at the paragraph in the book again (p. 68), there's no qualification, no distinction made between different reasons for commenting out code. So I wondered if this rule is over-generalizing (or if I misunderstood the book) or if what I do is bad practice, for some reason I didn't know.

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  • Why lock statements don't scale

    - by Alex.Davies
    We are going to have to stop using lock statements one day. Just like we had to stop using goto statements. The problem is similar, they're pretty easy to follow in small programs, but code with locks isn't composable. That means that small pieces of program that work in isolation can't necessarily be put together and work together. Of course actors scale fine :) Why lock statements don't scale as software gets bigger Deadlocks. You have a program with lots of threads picking up lots of locks. You already know that if two of your threads both try to pick up a lock that the other already has, they will deadlock. Your program will come to a grinding halt, and there will be fire and brimstone. "Easy!" you say, "Just make sure all the threads pick up the locks in the same order." Yes, that works. But you've broken composability. Now, to add a new lock to your code, you have to consider all the other locks already in your code and check that they are taken in the right order. Algorithm buffs will have noticed this approach means it takes quadratic time to write a program. That's bad. Why lock statements don't scale as hardware gets bigger Memory bus contention There's another headache, one that most programmers don't usually need to think about, but is going to bite us in a big way in a few years. Locking needs exclusive use of the entire system's memory bus while taking out the lock. That's not too bad for a single or dual-core system, but already for quad-core systems it's a pretty large overhead. Have a look at this blog about the .NET 4 ThreadPool for some numbers and a weird analogy (see the author's comment). Not too bad yet, but I'm scared my 1000 core machine of the future is going to go slower than my machine today! I don't know the answer to this problem yet. Maybe some kind of per-core work queue system with hierarchical work stealing. Definitely hardware support. But what I do know is that using locks specifically prevents any solution to this. We should be abstracting our code away from the details of locks as soon as possible, so we can swap in whatever solution arrives when it does. NAct uses locks at the moment. But my advice is that you code using actors (which do scale well as software gets bigger). And when there's a better way of implementing actors that'll scale well as hardware gets bigger, only NAct needs to work out how to use it, and your program will go fast on it's own.

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  • Countdown of Top 10 Reasons to Never Ever Use a Pie Chart

    - by Tony Wolfram
      Pie charts are evil. They represent much of what is wrong with the poor design of many websites and software applications. They're also innefective, misleading, and innacurate. Using a pie chart as your graph of choice to visually display important statistics and information demonstrates either a lack of knowledge, laziness, or poor design skills. Figure 1: A floating, tilted, 3D pie chart with shadow trying (poorly)to show usage statistics within a graphics application.   Of course, pie charts in and of themselves are not evil. This blog is really about designers making poor decisions for all the wrong reasons. In order for a pie chart to appear on a web page, somebody chose it over the other alternatives, and probably thought they were doing the right thing. They weren't. Using a pie chart is almost always a bad design decision. Figure 2: Pie Chart from an Oracle Reports User Guide   A pie chart does not do the job of effectively displaying information in an elegant visual form.  Being circular, they use up too much space while not allowing their labels to line up. Bar charts, line charts, and tables do a much better job. Expert designers, statisticians, and business analysts have documented their many failings, and strongly urge software and report designers not to use them. It's obvious to them that the pie chart has too many inherent defects to ever be used effectively. Figure 3: Demonstration of how comparing data between multiple pie charts is difficult.   Yet pie charts are still used frequently in today's software applications, financial reports, and websites, often on the opening page as a symbol of how the data inside is represented. In an attempt to get a flashy colorful graphic to break up boring text, designers will often settle for a pie chart that looks like pac man, a colored spinning wheel, or a 3D floating alien space ship.     Figure 4: Best use of a pie chart I've found yet.   Why is the pie chart so popular? Through its constant use and iconic representation as the classic chart, the idea persists that it must be a good choice, since everyone else is still using it. Like a virus or an urban legend, no amount of vaccine or debunking will slow down the use of pie charts, which seem to be resistant to logic and common sense. Even the new iPad from Apple showcases the pie chart as one of its options.     Figure 5: Screen shot of new iPad showcasing pie charts. Regardless of the futility in trying to rid the planet of this often used poor design choice, I now present to you my top 10 reasons why you should never, ever user a pie chart again.    Number 10 - Pie Charts Just Don't Work When Comparing Data Number 9 - You Have A Better Option: The Sorted Horizontal Bar Chart Number 8 - The Pie Chart is Always Round Number 7 - Some Genius Will Make It 3D Number 6 - Legends and Labels are Hard to Align and Read Number 5 - Nobody Has Ever Made a Critical Decision Using a Pie Chart Number 4 - It Doesn't Scale Well to More Than 2 Items Number 3 - A Pie Chart Causes Distortions and Errors Number 2 - Everyone Else Uses Them: Debunking the "Urban Legend" of Pie Charts Number 1 - Pie Charts Make You Look Stupid and Lazy  

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  • How to implement an email unsubscribe system for a site with many kinds of emails?

    - by Mike Liu
    I'm working on a website that features many different types of emails. Users have accounts, and when logged in they have access to a setting page that they can use to customize what types of emails they receive. However, I'd like to also give users an easy way to unsubscribe directly in the emails they receive. I've looked into list unsubscribe headers as well as creating some type of one click link that would unsubscribe a user from that type of email without requiring login or further action. The later would probably require me to break convention and make changes to the database in response to a GET on the link. However, am I incorrect in thinking that either of these would require me to generate and permanently store a unique identifier in my database for every email I ever send, really complicating email delivery? Without that, I'm not sure how I would be able to uniquely identify a user and a type of email in order to change their email preferences, and this identifier would need to be stored forever as a user could have an email sitting in their inbox for a long time before they decide to act on it. Alternatively, I was considering having a no-login page for managing email preferences. In contrast to above where I would need one of these identifiers for each email, this would only need one identifier per user, with no generation or other action required on sending an email. All of these raise security issues, and they could potentially be used by people to tamper with others' email preferences. This could be mitigated somewhat by ensuring that the identifier is really difficult to guess. For the once per user identifier approach, I was considering generating the identifier by passing a user's ID through some type of encryption algorithm, is this a sound approach? For the per-email identifiers, perhaps I could use a user's ID appended to the time. However, even this would not eliminate the problem entirely, as this would really just be security through obscurity, and anyone with the URL could tamper, and in the end the main defense would have to be that most people aren't so bored as to tamper with other people's email preferences. Are there any other alternatives I've missed, or issues or solutions with these that anyone can provide insight on? What are best practices in this area?

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  • Content Challenge: You Can Only Get it Here

    - by Mike Stiles
    Part of the content conundrum for brands is figuring out what kind of content customers would find cool, desirable, and relevant. The mere fact many brands have no idea what this content might be is, in itself, pretty alarming. You’d have to have a pretty thorough lack of involvement with and understanding of your customers to not know what they might like. But despite what should be a great awakening in which consumers are using every technology and trick in the book to shield themselves from ads and commercials, brand self-obsession continues as marketers concentrate on their message, their campaign, what they want to say, and what they want social users to do. When individuals conduct themselves in that same fashion on Facebook and Twitter, it gets tiresome and starts losing value pretty quickly. Their posts eventually get hidden. Conversely, friends who post things that consistently entertain or inform, with little self-marketing desperation involved, win the coveted “show all updates” setting. Of course brands are going to use social to market. It’s pretty much the point of having social in the marketing mix. And yes, people who follow a brand’s Twitter account or “Like” a brand’s Facebook Page implicitly state they want to know what’s going on with that brand’s products and services. But if you have a Facebook friend that assumes you want every one of her posts to be about what wine she likes (Mitsubishi’s current campaign is even based around weeding out pretentious Facebook friends, then running them over), then you know how it must feel for your fans and followers to get a sales pitch for your crackers or whatever you’re selling every single time. Is there such a thing as content that doesn’t sell but that still advances the brand and makes the consumer more involved and valuable? Of course. And perhaps there are no better companies than enterprise brands to do it. Enterprise organizations are large enough to go beyond a product and engage readers/viewers at higher, broader levels…communicating expertise across entire sectors, subjects and industries. You’re going from pitchman to news source, and getting full credit for it as the presenter. A recent GigaOM article pointed out the success a San Francisco-based startup called Crunchyroll is having. Their niche (and they proudly admit it’s a niche) is providing Japanese anime, Korean drama and Asian live action content to countries that can’t get it any other way via licensing deals. Shows are available in HD and on the same day they air in the host country. Crunchyroll not only gets 8 million viewers a month, they have 100,000 paying subscribers at $7-12/month. Got a point, Mike? I do happen to have one. Crunchyroll illustrates the content opportunity enterprise companies have…which is to determine your “area,” the interest graph of your customers, then provide content that speaks to and satisfies those interests that can’t be found anywhere else. At least not in the same style, or of the same quality, or with the same authority. Do what no one else is doing. Provide what no one else is providing in your sector. If underserved users are willing to pay monthly for access to awkwardly moving cartoon dragons, imagine the audience you could attract with free, useful, non-sales content in your customers’ area of interest. It’s an audience you’ll want in place when the time does come to put out that marketing message. A content challenge is better than a content conundrum any day.

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  • It's called College.

    - by jeffreyabecker
    Today I saw yet another 'GUID vs int as your primary key' article. Like most of the ones I've read this was filled with technical misrepresentations and out-right fallices. Chef's famous line that "There's a time and a place for everything children" applies here. GUIDs have distinct advantages and disadvantages which should be considered when choosing a data type for the primary key. Fallacy 1: "Its easier" An integer data type(tinyint, smallint, int, bigint) is a better artifical key than a GUID because its easier to remember. I'm a firm believer that your artifical primary keys should be opaque gibberish. PK's are an implementation detail which should never be exposed to the user or relied on for business logic. If you want things to come back in an order, add and ORDER BY clause and SortOrder fields. If you want a human-usable look-up add a business key with a unique constraint. If you want to know what order things were inserted into a table add a timestamp. Fallacy 2: "Size Matters" For many applications, the size of the artifical primary key is going to be irrelevant. The particular article which kicked this post off stated repeatedly that joining against an int has better performance than joining against a GUID. In computer science the performance of your algorithm is always a function of the number of data points. This still holds true for databases. Unless your table is very large, the performance difference between an int and a guid probably isnt going to be mesurable let alone noticeable. My personal experience is that the performance becomes an issue when you start having billions of rows in the table. At this point, you should probably start looking to move from int to bigint so the effective space/performance gain isnt as much as you'd think. GUID Advantages: Insert-ability / Mergeability: You can reliably insert guids into tables without key collisions. Database Independence: Saving entities to the database often requires knowing ids. With identity based ids the id must be selected back after every insert. GUIDs can be generated application-side allowing much faster inserts. GUID Disadvantages: Generatability: You can calculate the next id for an integer pk pretty easily in your head but will need a program to generate GUIDs. Solution: "Select top 100 newid() from sysobjects" Fragmentation: most GUID generation algorithms generate pseudo random GUIDs. This can cause inserts into the middle of your clustered index. Solutions: add a default of newsequentialid() or use GuidComb in NHibernate.

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  • Did I lost my RAID again?

    - by BarsMonster
    Hi! A little history: 2 years ago I was really excited to find out that mdadm is so powerful so it even can reshape arrays so you can start with a smaller array and the grow it as you need. I've bought 3x1Tb drives and made RAID-5. It was fine for a year. Then I bought 2x more, and tried to reshape to RAID-6 out of 5 drives, and due to some mess with superblock versions, lost all content. Had to rebuild it from scratch, but 2Tb of data were gone. Yesterday I bought 2 more drives, and this time I had everything: properly built array, UPS. I've disabled write intent map, added 2 new drives as a spare and run a command to grow array to 7-disk. It started working, but speed was ridiculously slow, ~100kb/sec. AFter processing first 37Mb at such an amasing speed, one of old HDDs fails. I properly shutdown PC and disconnected failed drive. After bootup it appeared it recreated intent map as it was still in mdadm config, so I removed it from config and rebooted again. Now all I see is that all mdadm processes deadlocks, and don't do anything. PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 1937 root 20 0 12992 608 444 D 0 0.1 0:00.00 mdadm 2283 root 20 0 12992 852 704 D 0 0.1 0:00.01 mdadm 2287 root 20 0 0 0 0 D 0 0.0 0:00.01 md0_reshape 2288 root 18 -2 12992 820 676 D 0 0.1 0:00.01 mdadm And all I see in mdstat is: $ cat /proc/mdstat Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10] md0 : active raid6 sdb1[1] sdg1[4] sdf1[7] sde1[6] sdd1[0] sdc1[5] 2929683456 blocks super 1.2 level 6, 1024k chunk, algorithm 2 [7/6] [UU_UUUU] [>....................] reshape = 0.0% (37888/976561152) finish=567604147.2min speed=0K/sec I've already tried mdadm 2.6.7, 3.1.4 and 3.2 - nothing helps. Did I lost my data again? Any suggestions how can I make it work? OS is Ubuntu Server 10.04.2... PS. Needless to say that data is unaccessible - I cannot mount /dev/md0 as save the most valuable data. You can see my disappointment - the very specific thing I was excited about failed twice taking 5Tb of my data with it.

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  • How to load stacking chunks on the fly?

    - by Brettetete
    I'm currently working on an infinite world, mostly inspired by minecraft. A Chunk consists of 16x16x16 blocks. A block(cube) is 1x1x1. This runs very smoothly with a ViewRange of 12 Chunks (12x16) on my computer. Fine. When I change the Chunk height to 256 this becomes - obviously - incredible laggy. So what I basically want to do is stacking chunks. That means my world could be [8,16,8] Chunks large. The question is now how to generate chunks on the fly? At the moment I generate not existing chunks circular around my position (near to far). Since I don't stack chunks yet, this is not very complex. As important side note here: I also want to have biomes, with different min/max height. So in Biome Flatlands the highest layer with blocks would be 8 (8x16) - in Biome Mountains the highest layer with blocks would be 14 (14x16). Just as example. What I could do would be loading 1 Chunk above and below me for example. But here the problem would be, that transitions between different bioms could be larger than one chunk on y. My current chunk loading in action For the completeness here my current chunk loading "algorithm" private IEnumerator UpdateChunks(){ for (int i = 1; i < VIEW_RANGE; i += ChunkWidth) { float vr = i; for (float x = transform.position.x - vr; x < transform.position.x + vr; x += ChunkWidth) { for (float z = transform.position.z - vr; z < transform.position.z + vr; z += ChunkWidth) { _pos.Set(x, 0, z); // no y, yet _pos.x = Mathf.Floor(_pos.x/ChunkWidth)*ChunkWidth; _pos.z = Mathf.Floor(_pos.z/ChunkWidth)*ChunkWidth; Chunk chunk = Chunk.FindChunk(_pos); // If Chunk is already created, continue if (chunk != null) continue; // Create a new Chunk.. chunk = (Chunk) Instantiate(ChunkFab, _pos, Quaternion.identity); } } // Skip to next frame yield return 0; } }

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  • Do I have to worry about "error: superfluous RAID member"?

    - by 0xC0000022L
    When running update-grub on the newly installed Ubuntu 12.04 with an older software RAID (md), I get: error: superfluous RAID member (5 found). error: superfluous RAID member (5 found). Generating grub.cfg ... error: superfluous RAID member (5 found). error: superfluous RAID member (5 found). error: superfluous RAID member (5 found). error: superfluous RAID member (5 found). error: superfluous RAID member (5 found). error: superfluous RAID member (5 found). error: superfluous RAID member (5 found). error: superfluous RAID member (5 found). error: superfluous RAID member (5 found). error: superfluous RAID member (5 found). error: superfluous RAID member (5 found). Found linux image: /boot/vmlinuz-3.2.0-24-generic Found initrd image: /boot/initrd.img-3.2.0-24-generic error: superfluous RAID member (5 found). error: superfluous RAID member (5 found). error: superfluous RAID member (5 found). error: superfluous RAID member (5 found). Found linux image: /boot/vmlinuz-3.2.0-23-generic Found initrd image: /boot/initrd.img-3.2.0-23-generic error: superfluous RAID member (5 found). error: superfluous RAID member (5 found). error: superfluous RAID member (5 found). error: superfluous RAID member (5 found). error: superfluous RAID member (5 found). Found memtest86+ image: /boot/memtest86+.bin error: superfluous RAID member (5 found). error: superfluous RAID member (5 found). error: superfluous RAID member (5 found). error: superfluous RAID member (5 found). error: superfluous RAID member (5 found). Found Debian GNU/Linux (5.0.9) on /dev/sdb1 Found Debian GNU/Linux (5.0.9) on /dev/sdc1 done I would be less worried if the message would say warning: ..., but since it says error: ... I'm wondering what the problem is. # cat /proc/mdstat Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10] md2 : active raid1 sdc1[1] sdb1[0] 48829440 blocks [2/2] [UU] md3 : active raid1 sdc2[1] sdb2[0] 263739008 blocks [2/2] [UU] md1 : active raid5 sdg1[3] sdf1[2] sde1[1] sdh1[0] sdi1[4] sdd1[5](S) 1250274304 blocks level 5, 64k chunk, algorithm 2 [5/5] [UUUUU] unused devices: <none> Do I have to worry or is this harmless? btw: disregard the mentioning of Debian 5.0.9, that was the previously installed system and is going to be overwritten. It's on /dev/md2 actually.

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  • What does the `dmesg` error: "composite sync not supported" mean?

    - by M. Tibbits
    Question: I see [ 20.473125] composite sync not supported and several such entries when I run dmesg. What do they mean? Background: I'm trying to debug a problem where my laptop won't suspend. Since acpi seems happy and I can suspend easily from the command line, I've turned to tracking down all boot-up errors/warnings. So I run dmesg | grep not and, amongst other shtuff, I get: 728:[ 17.267120] composite sync not supported 733:[ 18.009061] composite sync not supported 740:[ 18.159289] registered panic notifier 749:[ 18.162500] vga16fb: not registering due to another framebuffer present 757:[ 18.598251] composite sync not supported 776:[ 20.473125] composite sync not supported 777:[ 20.932266] composite sync not supported 778:[ 28.350231] composite sync not supported 779:[ 28.924913] composite sync not supported 780:[ 35.480658] composite sync not supported And the full log for the few lines right around that first appearance (line 728) is listed at the bottom of my post (I'd happily include anything else). Any ideas what could be causing this? I've read several sites: Ubuntuforums #1 IRC Chat #1 One post talks about ??Adobe flash?? causing this error? Some others also suggest that it might be an nvidia related problem, but I've got a Dell Latitude D630 with an integrated Intel graphics -- so nvidia isn't the problem. [ 17.207142] phy0: Selected rate control algorithm 'minstrel' [ 17.207833] Registered led device: b43-phy0::tx [ 17.207849] Registered led device: b43-phy0::rx [ 17.207865] Registered led device: b43-phy0::radio [ 17.207927] Broadcom 43xx driver loaded [ Features: PL, Firmware-ID: FW13 ] [ 17.267120] composite sync not supported [ 17.415795] EXT4-fs (sda2): mounted filesystem with ordered data mode [ 17.602131] [drm] initialized overlay support [ 17.620201] input: DualPoint Stick as /devices/platform/i8042/serio1/input/input7 [ 17.641192] input: AlpsPS/2 ALPS DualPoint TouchPad as /devices/platform/i8042/serio1/input/input8 [ 18.009061] composite sync not supported [ 18.106042] pcmcia_socket pcmcia_socket0: cs: IO port probe 0x100-0x3af: clean. [ 18.108115] pcmcia_socket pcmcia_socket0: cs: IO port probe 0x3e0-0x4ff: clean. [ 18.108941] pcmcia_socket pcmcia_socket0: cs: IO port probe 0x820-0x8ff: clean. [ 18.109676] pcmcia_socket pcmcia_socket0: cs: IO port probe 0xc00-0xcf7: clean. [ 18.110356] pcmcia_socket pcmcia_socket0: cs: IO port probe 0xa00-0xaff: clean. [ 18.159286] fb0: inteldrmfb frame buffer device [ 18.159289] registered panic notifier [ 18.160218] input: Video Bus as /devices/LNXSYSTM:00/LNXSYBUS:00/PNP0A03:00/LNXVIDEO:01/input/input9 [ 18.160286] ACPI: Video Device [VID1] (multi-head: yes rom: no post: no) [ 18.160334] ACPI Warning for \_SB_.PCI0.VID2._DOD: Return Package has no elements (empty) (20090903/nspredef-433) [ 18.160432] input: Video Bus as /devices/LNXSYSTM:00/LNXSYBUS:00/PNP0A03:00/LNXVIDEO:02/input/input10 [ 18.160491] ACPI: Video Device [VID2] (multi-head: yes rom: no post: no) [ 18.160539] [drm] Initialized i915 1.6.0 20080730 for 0000:00:02.0 on minor 0 [ 18.162494] vga16fb: initializing [ 18.162497] vga16fb: mapped to 0xc00a0000 [ 18.162500] vga16fb: not registering due to another framebuffer present [ 18.176091] HDA Intel 0000:00:1b.0: PCI INT A -> GSI 21 (level, low) -> IRQ 21 [ 18.176123] HDA Intel 0000:00:1b.0: setting latency timer to 64 [ 18.285752] input: HDA Digital PCBeep as /devices/pci0000:00/0000:00:1b.0/input/input11 [ 18.312497] input: HDA Intel Mic at Ext Left Jack as /devices/pci0000:00/0000:00:1b.0/sound/card0/input12 [ 18.312586] input: HDA Intel HP Out at Ext Left Jack as /devices/pci0000:00/0000:00:1b.0/sound/card0/input13 [ 18.328043] usbcore: registered new interface driver ndiswrapper [ 18.460909] Console: switching to colour frame buffer device 180x56 [ 18.598251] composite sync not supported

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  • SQL – Contest to Get The Date – Win USD 50 Amazon Gift Cards and Cool Gift

    - by Pinal Dave
    If you are a regular reader of this blog – you will find no issue at all in resolving this puzzle. This contest is based on my experience with NuoDB. If you are not familiar with NuoDB, here are few pointers for you. Step by Step Guide to Download and Install NuoDB – Getting Started with NuoDB Quick Start with Admin Sections of NuoDB – Manage NuoDB Database Quick Start with Explorer Sections of NuoDB – Query NuoDB Database In today’s contest you have to answer following questions: Q 1: Precision of NOW() What is the precision of the NuoDB’s NOW() function, which returns current date time? Hint: Run following script on NuoDB Console Explorer section: SELECT NOW() AS CurrentTime FROM dual; Here is the image. I have masked the area where the time precision is displayed. Q 2: Executing Date and Time Script When I execute following script - SELECT 'today' AS Today, 'tomorrow' AS Tomorrow, 'yesterday' AS Yesterday FROM dual; I will get the following result:   NOW – What will be the answer when we execute following script? and WHY? SELECT CAST('today' AS DATE) AS Today, CAST('tomorrow' AS DATE) AS Tomorrow, CAST('yesterday'AS DATE) AS Yesterday FROM dual; HINT: Install NuoDB (it takes 90 seconds). Prizes: 2 Amazon Gifts 2 Limited Edition Hoodies (US resident only)   Rules: Please leave an answer in the comments section below. You must answer both the questions together in a single comment. US resident who wants to qualify to win NuoDB apparel please mention your country in the comment. You can resubmit your answer multiple times, the latest entry will be considered valid. Last day to participate in the puzzle is June 24, 2013. All valid answer will be kept hidden till June 24, 2013. The winner will be announced on June 25, 2013. Two Winners will get USD 25 worth Amazon Gift Card. (Total Value = 25 x 2 = 50 USD) The winner will be selected using a random algorithm from all the valid answers. Anybody with a valid email address can take part in the contest. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Big Data, PostADay, SQL, SQL Authority, SQL Puzzle, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: NuoDB

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  • Slow Ubuntu 10.04 after long time unused

    - by Winston Ewert
    I'm at spring break so I'm back at my parent's house. I've turned my computer on which has been off since January and its unusably slow. This was not the case when I last used the computer in January. It is running 10.04, Memory: 875.5 MB CPU: AMD Athlon 64 X2 Dual Core Processor 4400+ Available Disk Space: 330.8 GB I'm not seeing a large usage of either memory or Disk I/O. If I look at my list of processes there is only a very small amount of CPU usage. However, if I hover over the CPU usage graph that I've on the top bar, I sometimes get really high readings like 100%. It took a long time to boot, to open firefox, to open a link in firefox. As far as I can tell everything that the computer tries to do is just massively slow. Right now, I'm apt-get dist-upgrading to install any updates that I will have missed since last time this computer was on. Any ideas as to what is going on here? UPDATE: I thought to check dmesg and it has a lot of entries like this: [ 1870.142201] ata3.00: exception Emask 0x0 SAct 0x7 SErr 0x0 action 0x0 [ 1870.142206] ata3.00: irq_stat 0x40000008 [ 1870.142210] ata3.00: failed command: READ FPDMA QUEUED [ 1870.142217] ata3.00: cmd 60/08:10:c0:4a:65/00:00:03:00:00/40 tag 2 ncq 4096 in [ 1870.142218] res 41/40:00:c5:4a:65/00:00:03:00:00/40 Emask 0x409 (media error) <F> [ 1870.142221] ata3.00: status: { DRDY ERR } [ 1870.142223] ata3.00: error: { UNC } [ 1870.143981] ata3.00: SB600 AHCI: limiting to 255 sectors per cmd [ 1870.146758] ata3.00: SB600 AHCI: limiting to 255 sectors per cmd [ 1870.146761] ata3.00: configured for UDMA/133 [ 1870.146777] ata3: EH complete [ 1872.092269] ata3.00: exception Emask 0x0 SAct 0x7 SErr 0x0 action 0x0 [ 1872.092274] ata3.00: irq_stat 0x40000008 [ 1872.092278] ata3.00: failed command: READ FPDMA QUEUED [ 1872.092285] ata3.00: cmd 60/08:00:c0:4a:65/00:00:03:00:00/40 tag 0 ncq 4096 in [ 1872.092287] res 41/40:00:c5:4a:65/00:00:03:00:00/40 Emask 0x409 (media error) <F> [ 1872.092289] ata3.00: status: { DRDY ERR } [ 1872.092292] ata3.00: error: { UNC } [ 1872.094050] ata3.00: SB600 AHCI: limiting to 255 sectors per cmd [ 1872.096795] ata3.00: SB600 AHCI: limiting to 255 sectors per cmd [ 1872.096798] ata3.00: configured for UDMA/133 [ 1872.096814] ata3: EH complete [ 1874.042279] ata3.00: exception Emask 0x0 SAct 0x7 SErr 0x0 action 0x0 [ 1874.042285] ata3.00: irq_stat 0x40000008 [ 1874.042289] ata3.00: failed command: READ FPDMA QUEUED [ 1874.042296] ata3.00: cmd 60/08:10:c0:4a:65/00:00:03:00:00/40 tag 2 ncq 4096 in [ 1874.042297] res 41/40:00:c5:4a:65/00:00:03:00:00/40 Emask 0x409 (media error) <F> [ 1874.042300] ata3.00: status: { DRDY ERR } [ 1874.042302] ata3.00: error: { UNC } [ 1874.044048] ata3.00: SB600 AHCI: limiting to 255 sectors per cmd [ 1874.046837] ata3.00: SB600 AHCI: limiting to 255 sectors per cmd [ 1874.046840] ata3.00: configured for UDMA/133 [ 1874.046861] sd 2:0:0:0: [sda] Unhandled sense code [ 1874.046863] sd 2:0:0:0: [sda] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE [ 1874.046867] sd 2:0:0:0: [sda] Sense Key : Medium Error [current] [descriptor] [ 1874.046872] Descriptor sense data with sense descriptors (in hex): [ 1874.046874] 72 03 11 04 00 00 00 0c 00 0a 80 00 00 00 00 00 [ 1874.046883] 03 65 4a c5 [ 1874.046886] sd 2:0:0:0: [sda] Add. Sense: Unrecovered read error - auto reallocate failed [ 1874.046892] sd 2:0:0:0: [sda] CDB: Read(10): 28 00 03 65 4a c0 00 00 08 00 [ 1874.046900] end_request: I/O error, dev sda, sector 56969925 [ 1874.046920] ata3: EH complete I'm not certain, but that looks like my problem may be a failing hard drive. But the drive is less then a year old, it really shouldn't be failing now...

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  • Creating predefinied camera views - How do I move the camera to make sense while using Controller?

    - by Deukalion
    I'm trying to understand 3D but the one thing I can't seem to understand is the Camera. Right now I'm rendering four 3D Cubes with textures and I set the Project Matrix: public BasicCamera3D(float fieldOfView, float aspectRatio, float clipStart, float clipEnd, Vector3 cameraPosition, Vector3 cameraLookAt) { projection_fieldOfView = MathHelper.ToRadians(fieldOfView); projection_aspectRatio = aspectRatio; projection_clipstart = clipStart; projection_clipend = clipEnd; matrix_projection = Matrix.CreatePerspectiveFieldOfView(projection_fieldOfView, aspectRatio, clipStart, clipEnd); view_cameraposition = cameraPosition; view_cameralookat = cameraLookAt; matrix_view = Matrix.CreateLookAt(cameraPosition, cameraLookAt, Vector3.Up); } BasicCamera3D gameCamera = new BasicCamera3D(45f, GraphicsDevice.Viewport.AspectRatio, 1.0f, 1000f, new Vector3(0, 0, 8), new Vector3(0, 0, 0)); This creates a sort of "Top-Down" camera, with 8 (still don't get the unit type here - it's not pixels I guess?) But, if I try to position the camera at the side to make "Side-View" or "Reverse Side View" camera, the camera is rotating to much until it's turned around it a couple of times. I render the boxes at: new Vector3(-1, 0, 0) new Vector3(0, 0, 0) new Vector3(1, 0, 0) new Vector3(1, 0, 1) and with the Top-Down camera it shows good, but I don't get how I can make the camera show the side or 45 degrees from top (Like 3rd person action games) because the logic doesn't make sense. Also, since every object you render needs a new BasicEffect with a new projection/view/world - can you still use the "same" camera always so you don't have to create a new View/Matrix and such for each object. It's seems weird. If someone could help me get the camera to navigate around my objects "naturally" so I can be able to set a few predtermined views to choose from it would be really helpful. Are there some sort of algorithm to calculate the view for this and perhaps not simply one value? Examples: Top-Down-View: I have an object at 0, 0, 0 when I turn the right stick on the Xbox 360 Controller it should rotate around that object kind of, not flip and turn upside down, disappear and then magically appear as a tiny dot somewhere I have no clue where it is like it feels like it does now. Side-View: I have an object at 0, 0, 0 when I rotate to sides or up and down, the camera should be able to show a little more of the periphery to each side (depending on which you look at), and the same while moving up or down.

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  • 45 minutes to talk about C# [closed]

    - by Philip
    I have the opportunity to give a 45 minute talk on C# in the theory of programming languages class I'm taking. The college teaches Java almost exclusively, so that's what all the students are most familiar with. (There's a little C, assembly, Prolog and LISP as well.) I decide what to talk about. It seems to me the best approach is to focus on a few of the big, obvious differences between C# and Java. I don't intend it to be a recommendation to use C# -- there are reasons to use each, mostly because of their ecosystems. So I want to focus on C# as a language. I don't want to go too fast and end up listing a whole bunch of features without showing their usefulness. My current plan is this: Functions as first class objects. This is, in my opinion, one of the biggest differences between C# and Java. The professor briefly mentioned this notion and showed a LISP example, but many of the students have probably never used it. I can show real world examples where it's made my code more readable. Lambda expressions as concise syntax for anonymous functions. Obviously with examples to show how this is useful. The real hit-home examples will be at the end when it's combined with the rest. I don't see an advantage to first showing the old delegate syntax and then replacing it with lambdas -- most of us won't have ever seen delegates anyway so it would just be confusing. The yield keyword and how it's different from returning an array. I have the impression that a lot of C# developers aren't familiar with how to use this. It will likely be very foreign to Java developers. I have some examples from my own work where it was really useful, such as iterating over a tree traversal, or iterating over neighbors in a graph where the neighbors aren't stored in memory. In both cases, doing it in Java would likely mean returning a complete list -- with yield I can stop iterating if I find what I want early on, without using memory for superfluous lists or arrays. Extension methods as a way to write implementation on interfaces. We'll all be familiar with how interfaces don't allow method implementation, and how this leads to code duplication. I'll show a specific example of this and how the extension method can solve the problem. Demonstrate how the above can be combined by implementing some simple Linq methods and using them. Where, Select, First, maybe more depending on how much time is left. Ideas on which ones might 'hit home' the best? There are other things I could talk about such as generics, value types, properties and more. I haven't yet though of good ways to incorporate these. In the case of generics and value types, the advantages might not be obvious or as relevant. Properties are obviously useful, particularly since we're taught strict JavaBeans here, but I don't know if I could integrate it with the "path to Linq" discussion above without it feeling tacked on. So I'm looking for thoughts on how to talk about C#, and what to talk about. Even minor details. I'm sure there are more experienced C# developers than me here who have good insight about what's really important in the language, and what would miss the point.

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  • DataContractSerializer: type is not serializable because it is not public?

    - by Michael B. McLaughlin
    I recently ran into an odd and annoying error when working with the DataContractSerializer class for a WP7 project. I thought I’d share it to save others who might encounter it the same annoyance I had. So I had an instance of  ObservableCollection<T> that I was trying to serialize (with T being a class I wrote for the project) and whenever it would hit the code to save it, it would give me: The data contract type 'ProjectName.MyMagicItemsClass' is not serializable because it is not public. Making the type public will fix this error. Alternatively, you can make it internal, and use the InternalsVisibleToAttribute attribute on your assembly in order to enable serialization of internal members - see documentation for more details. Be aware that doing so has certain security implications. This, of course, was malarkey. I was trying to write an instance of MyAwesomeClass that looked like this: [DataContract] public class MyAwesomeClass { [DataMember] public ObservableCollection<MyMagicItemsClass> GreatItems { get; set; }   [DataMember] public ObservableCollection<MyMagicItemsClass> SuperbItems { get; set; }     public MyAwesomeClass { GreatItems = new ObservableCollection<MyMagicItemsClass>(); SuperbItems = new ObservableCollection<MyMagicItemsClass>(); } }   That’s all well and fine. And MyMagicItemsClass was also public with a parameterless public constructor. It too had DataContractAttribute applied to it and it had DataMemberAttribute applied to all the properties and fields I wanted to serialize. Everything should be cool, but it’s not because I keep getting that “not public” exception. I could tell you about all the things I tried (generating a List<T> on the fly to make sure it wasn’t ObservableCollection<T>, trying to serialize the the Collections directly, moving it all to a separate library project, etc.), but I want to keep this short. In the end, I remembered my the “Debug->Exceptions…” VS menu option that brings up the list of exception-related circumstances under which the Visual Studio debugger will break. I checked the “Thrown” checkbox for “Common Language Runtime Exceptions”, started the project under the debugger, and voilà: the true problem revealed itself. Some of my properties had fairly elaborate setters whose logic I wanted to ignore. So for some of them, I applied an IgnoreDataMember attribute to them and applied the DataMember attribute to the underlying fields instead. All of which, in line with good programming practices, were private. Well, it just so happens that WP7 apps run in a “partial trust” environment and outside of “full trust”-land, DataContractSerializer refuses to serialize or deserialize non-public members. Of course that exception was swallowed up internally by .NET so all I ever saw was that bizarre message about things that I knew for certain were public being “not public”. I changed all the private fields I was serializing to public and everything worked just fine. In hindsight it all makes perfect sense. The serializer uses reflection to build up its graph of the object in order to write it out. In partial trust, you don’t want people using reflection to get at non-public members of an object since there are potential security problems with allowing that (you could break out of the sandbox pretty quickly by reflecting and calling the appropriate methods and cause some havoc by reflecting and setting the appropriate fields in certain circumstances. The fact that you cannot reflect your own assembly seems a bit heavy-handed, but then again I’m not a compiler writer or a framework designer and I have no idea what sorts of difficulties would go into allowing that from a compilation standpoint or what sorts of security problems allowing that could present (if any). So, lesson learned. If you get an incomprehensible exception message, turn on break on all thrown exceptions and try running it again (it might take a couple of tries, depending) and see what pops out. Chances are you’ll find the buried exception that actually explains what was going on. And if you’re getting a weird exception when trying to use DataContractSerializer complaining about public types not being public, chances are you’re trying to serialize a private or protected field/property.

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  • Are there deprecated practices for multithread and multiprocessor programming that I should no longer use?

    - by DeveloperDon
    In the early days of FORTRAN and BASIC, essentially all programs were written with GOTO statements. The result was spaghetti code and the solution was structured programming. Similarly, pointers can have difficult to control characteristics in our programs. C++ started with plenty of pointers, but use of references are recommended. Libraries like STL can reduce some of our dependency. There are also idioms to create smart pointers that have better characteristics, and some version of C++ permit references and managed code. Programming practices like inheritance and polymorphism use a lot of pointers behind the scenes (just as for, while, do structured programming generates code filled with branch instructions). Languages like Java eliminate pointers and use garbage collection to manage dynamically allocated data instead of depending on programmers to match all their new and delete statements. In my reading, I have seen examples of multi-process and multi-thread programming that don't seem to use semaphores. Do they use the same thing with different names or do they have new ways of structuring protection of resources from concurrent use? For example, a specific example of a system for multithread programming with multicore processors is OpenMP. It represents a critical region as follows, without the use of semaphores, which seem not to be included in the environment. th_id = omp_get_thread_num(); #pragma omp critical { cout << "Hello World from thread " << th_id << '\n'; } This example is an excerpt from: http://en.wikipedia.org/wiki/OpenMP Alternatively, similar protection of threads from each other using semaphores with functions wait() and signal() might look like this: wait(sem); th_id = get_thread_num(); cout << "Hello World from thread " << th_id << '\n'; signal(sem); In this example, things are pretty simple, and just a simple review is enough to show the wait() and signal() calls are matched and even with a lot of concurrency, thread safety is provided. But other algorithms are more complicated and use multiple semaphores (both binary and counting) spread across multiple functions with complex conditions that can be called by many threads. The consequences of creating deadlock or failing to make things thread safe can be hard to manage. Do these systems like OpenMP eliminate the problems with semaphores? Do they move the problem somewhere else? How do I transform my favorite semaphore using algorithm to not use semaphores anymore?

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  • 13 MORE Things from the Oracle Social Summit You Should Know

    - by Mike Stiles
    In our previous blog, we started giving those of you who couldn’t make it just a sampling of the valuable takeaways from the first annual Oracle Social Summit, held Nov 14 and 15 in Las Vegas. And while yes, 13 items is a pretty healthy sampling, we wanted to go the extra mile and give you 13 more, an indication of just how much great information came out of it.  Follow the arrow, and come on in as if you were there with us. 1. Weber Shandwick takes a 70/20/10 approach when advising clients how to allocate resources to paid social opportunities. 70% of spend should go toward paid opportunities the agency and client both know work, 20% should go toward paid social the agency knows works, and 10% should go toward experimentation. (Matt Dickman – Weber Shandwick) 2. By 2017, the technically competent CMO will spend more on IT than the CIO. (Gartner Study) 3. CIOs are focused on infrastructure. As the roles of the CMO and CIO continue coming together, those CIOs have to make a very conscious decision to get CMOs what they need. 4. It’s now harder for brands to differentiate based on product. The advantage will go to the brands that are successful in garnering customer trust. 5. More and more, enterprise software is going to start looking like the software consumers are used to seeing and using. 6. You will see brands prioritizing mobile and dropping investments in www, HTML, POS systems, etc. 7. The social graph has to be added to brands’ customer data for a more holistic view. Customers will give you the information you need if the reward is appropriate. 8. Viacom did a study that showed viewers are most honest on social. Not so much on surveys or other feedback vehicles. 9. How are you determining your influencers? Influence isn’t about reach. It’s about getting people to change behavior. 10. A mix of skills is becoming critically important in a social staff. It shouldn’t be a mixture of several disciplines, not just a bunch of “social experts.” 11. If senior management isn’t engaged, the social team is forced into guessing what might be considered a “success” by the C-suite. 12. Mobile customization will be getting big investments from brands in 2013. Brands need to provide shoppers utility, not just information. 75% will use mobile this holiday season to avoid in-store madness. 13. Data becomes information, information becomes insight, and insight becomes actionable. The Oracle Social Summit brought together brands, agencies, Oracle social experts and industry thought leaders to take a serious look at where social stands today, and where it’s headed in the near future. Given the speed of social’s evolution, attending such events (or at least reading nifty summary blogs) is a good investment in making sure your enterprise isn’t falling gradually behind.

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  • How can I convert a 2D bitmap (Used for terrain) to a 2D polygon mesh for collision?

    - by Megadanxzero
    So I'm making an artillery type game, sort of similar to Worms with all the usual stuff like destructible terrain etc... and while I could use per-pixel collision that doesn't give me collision normals or anything like that. Converting it all to a mesh would also mean I could use an existing physics library, which would be better than anything I can make by myself. I've seen people mention doing this by using Marching Squares to get contours in the bitmap, but I can't find anything which mentions how to turn these into a mesh (Unless it refers to a 3D mesh with contour lines defining different heights, which is NOT what I want). At the moment I can get a basic Marching Squares contour which looks something like this (Where the grid-like lines in the background would be the Marching Squares 'cells'): That needs to be interpolated to get a smoother, more accurate result but that's the general idea. I had a couple ideas for how to turn this into a mesh, but many of them wouldn't work in certain cases, and the one which I thought would work perfectly has turned out to be very slow and I've not even finished it yet! Ideally I'd like whatever I end up using to be fast enough to do every frame for cases such as rapidly-firing weapons, or digging tools. I'm thinking there must be some kind of existing algorithm/technique for turning something like this into a mesh, but I can't seem to find anything. I've looked at some things like Delaunay Triangulation, but as far as I can tell that won't correctly handle concave shapes like the above example, and also wouldn't account for holes within the terrain. I'll go through the technique I came up with for comparison and I guess I'll see if anyone has a better idea. First of all interpolate the Marching Squares contour lines, creating vertices from the line ends, and getting vertices where lines cross cell edges (Important). Then, for each cell containing vertices create polygons by using 2 vertices, and a cell corner as the 3rd vertex (Probably the closest corner). Do this for each cell and I think you should have a mesh which accurately represents the original bitmap (Though there will only be polygons at the edges of the bitmap, and large filled in areas in between will be empty). The only problem with this is that it involves lopping through every pixel once for the initial Marching Squares, then looping through every cell (image height + 1 x image width + 1) at least twice, which ends up being really slow for any decently sized image...

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  • How can I solve this SAT edge case?

    - by ssb
    I have an SAT implementation that basically works, and the fact that it works is what's giving me a few headaches. Basically there are some situations where using the SAT doesn't quite give me my intended result. One of these involves movement across multiple collision objects. Or to put it another way, if I have several collision boxes lined up next to each other such as to create something like a wall or a floor, movement along that surface while constantly applying force into that surface sometimes causes hangups, i.e. the player stops moving. This illustration shows what I mean: The 2 boxes on the bottom represent a floor, and the box on top/in the middle represents what my player is doing. There are several squares lined up as world obstacles to create some kind of wall, and if I move to the left across this surface while holding the down key then the issue arises. It only happens at the exact dividing point between two blocks. It only happens when moving to the left. At any rate I think I know why it happens, but I don't know how to solve it. Basically when I update my player movement I consider which directions are pressed, naturally, so if down is pressed I will add the speed to the Y component, and so on. But due to the way my SAT is implemented, when the penetration into the shape is the same from both sides it just goes with the smallest axis that it finds first, and it checks collisions against objects in the order that they were created because it goes through a foreach loop on the list of collidable objects. So this all adds up to the effect of if I'm moving to the left over a series of boxes while holding down, it will resolve me back to the right out of the first box and then up out of the box to the right of it, and this continues as long as the penetration is the same. The odd part is that this doesn't happen every time, which I am going to attribute to some oddity regarding multiplying velocity by the game time and causing some minor discrepancies between the lengths. Ultimately what this boils down to is that it will keep resolving me to the right and up, but this is technically expected behavior. All the solutions I can think of only address the symptoms of this problem and not the actual cause, such as not using many blocks to create walls or shapes, which is an option I'd like to keep open. I could also change which axis my algorithm defaults to, but that would just cause problems when going up/down along the walls. What can I do to fix this?

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