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• Attunity Oracle CDC Solution for SSIS - Beta

  We in no way work for Attunity but we were asked to test drive a beta version of their Oracle CDC solution for SSIS.  Everybody should know that moving more data than you need to takes too much time and uses resources that may better be employed doing something else.  Change data Capture is a technology that is designed to help you identify only the data that has had something done to it and you can therefore move only what is needed.  Microsoft have implemented this exact functionality into SQL server 2008 and I really like it there.  Attunity though are doing it on Oracle. DISCLAIMER: This is a BETA release and some of the parts are a bit ugly/difficult to work with.  The idea though is definitely right and the product once working does exactly what it says on the tin.  They have always been helpful to me when I have had a problem with the product and if that continues then beta testing pain should be eased somewhat. In due course I am going to be doing some videos around me using the product.  If you use Oracle and SSIS then give it a go. Here is their product description.   Attunity is a Microsoft SQL Server technology partner and the creator of the Microsoft Connectors for Oracle and Teradata, currently available in SQL Server 2008 Enterprise Edition. Attunity released a beta version of the Attunity Oracle-CDC for SSIS, a product that integrates continually changing Oracle data into SSIS, efficiently and in real-time. Attunity designed the product and integrated it into SSIS to create the simple creation of change data capture (CDC) solutions, accelerate implementation time, and reduce resources and costs. They also utilize log-based CDC so the solution has minimal impact on the Oracle source system. You can use the product to implement enterprise-class data replication, synchronization, and real-time business intelligence (BI) and data warehousing projects, quickly and efficiently, leveraging their existing SQL Server investments and resource skills. Attunity architected the product specifically for the Microsoft SSIS developer community and the product is available for both SQL Server 2005 and SQL Server 2008. It offers the following key capabilities: · Log-based, non-intrusive Oracle CDC · Full integration into SSIS and the Business Intelligence Developer Studio · Automatic generation of SSIS packages for CDC as well as full-loads of Oracle data · Filtering of Oracle tables and columns at the source · Monitoring and control of CDC processing Click to learn more and download the beta.

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• Configurable Objects - Introduction

  - by Anthony Shorten

  One of the interesting facilities in the framework is Configurable Object functionality (it is also known as Task Optimization and also known as Cool Tools). The idea is that any implementation can create their own views of the base product objects and services and implement functionality against those new views. For example, in Oracle Utilities Customer Care and Billing, there is a Person object. That object is used to store and manage information about individuals as well as companies. In the base product you would use the Person Maintenance screen and fill in some of the screen when you wanted to register or maintain and individual as well and fill out other parts of the screen when you wanted to register or maintain a company. This can be somewhat confusing to some customers. Using Configurable Objects this can be simplified. A business object can be created that is a view of the any object. For example, you could create a Human business object which would cover the aspects of the Person object pertaining to an individual and a Company business object to cover the aspects unique to a company. Even the tag names (i.e. Field Names) in the object can be changed to be more what the implementation is familiar with. The object can also restructure the object. For example, a common identifier for an individual in the USA is the Social Security number, this value is a Person Identifier (as this varies in each country). In the new Human object you can remap the Person Identifier as a Social Security number. To define a Business Object you use a schema editor built into the browser user interface and use a mapping language to setup the business objects. An example of the language is shown below in an extract of the schema for the Human business object. As you can see there are mapping as well as formatting and other tags. This information can be built manually or using a wizard which generates the base structure for you to alter. This is all stored as meta data when saved. Once a Business object is built it can be used as basis for code, other business objects (we support inheritance), called by a screen (called a UI Map) or even as a Web Service. This is just a start with Configurable Objects as you can also create views of base services called Business Services, Service Scripts used for non-object or complex object processing (as well as other things), UI Maps used for screens and Data Areas to reuse definitions across multiple objects. Configurable Objects are powerful and I only really touched on them here. Over the next few months I hope to add lots more entries about them.

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• Keybindings for individual letter keys (not modifier-combinations) on a GtkTextView widget (Gtk3 and PyGI)

  - by monotasker

  I've been able to set several keybord shortcuts for a GtkTextView and a GtkTextEntry using the new css provider system. I'm finding, though, that I only seem to be able to establish keybindings for combinations including a modifier key. The widget doesn't respond to any bindings I set up that use: the delete key the escape key individual letter or punctuation keys alone Here's the code where I set up the css provider for the keybindings: #set up style context keys = Gtk.CssProvider() keys.load_from_path(os.path.join(data_path, 'keybindings.css')) #set up style contexts and css providers widgets = {'window': self.window, 'vbox': self.vbox, 'toolbar': self.toolbar, 'search_entry': self.search_entry, 'paned': self.paned, 'notelist_treeview': self.notelist_treeview, 'notelist_window': self.notelist_window, 'notetext_window': self.notetext_window, 'editor': self.editor, 'statusbar': self.statusbar } for l, w in widgets.iteritems(): w.get_style_context().add_provider(keys, Gtk.STYLE_PROVIDER_PRIORITY_USER) Then in keybindings.css this is an example of what works: @binding-set gtk-vi-text-view { bind "<ctrl>b" { "move-cursor" (display-lines, -5, 0) }; /* 5 lines up */ bind "<ctrl>k" { "move-cursor" (display-lines, -1, 0) }; /* down */ bind "<ctrl>j" { "move-cursor" (display-lines, 1, 0) }; /* up */ } Part of what I'm trying to do is just add proper delete-key function to the text widgets (right now the delete key does nothing at all). So if I add a binding like one of these, nothing happens: bind "Delete" { "delete-selection" () }; bind "Delete" { "delete-from-cursor" (chars, 1) }; The other part of what I want to do is more elaborate. I want to set up something like Vim's command and visual modes. So at the moment I'm just playing around with (a) setting the widget to editable=false by hitting the esc key; and (b) using homerow letters to move the cursor (as a proof-of-concept exercise). So far there's no response from the escape key or from the letter keys, even though the bindings work when I apply them to modifier-key combinations. For example, I do this in the css for the text-widget: bind "j" { "move-cursor" (display-lines, 1, 0) }; /* down */ bind "k" { "move-cursor" (display-lines, -1, 0) }; /* up */ bind "l" { "move-cursor" (logical-positions, 1, 0) }; /* right */ bind "h" { "move-cursor" (logical-positions, -1, 0) }; /* left */ but none of these bindings does anything, even if other bindings in the same set are respected. What's especially odd is that the vim-like movement bindings above are respected when I attach them to a GtkTreeView widget for navigating the tree-view options: @binding-set gtk-vi-tree-view { bind "j" { "move-cursor" (display-lines, 1) }; /* selection down */ bind "k" { "move-cursor" (display-lines, -1) }; /* selection up */ } So it seems like there are limitations or overrides of some kind on keybindings for the TextView widget (and for the del key?), but I can't find documentation of anything like that. Are these just things that can't be done with the css providers? If so, what are my alternatives for non-modified keybindings? Thanks.

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• Dynamic character animation - Using the physics engine or not

  - by Lex Webb

  I'm planning on building a dynamic reactant animation engine for the characters in my 2D Game. I have already built templates for a skeleton based animation system using key frames and interpolation to specify a limbs position at any given moment in time. I am using Farseer physics (an extension of Box2D) in Monogame/XNA in C# My real question lies in how i go about tying this character animation into the physics engine. I have two options: Moving limbs using physics engine - applying a interpolated force to each limb (dynamic body) in order to attempt to get it to its position as donated by the skeleton animation. Moving limbs by simply changing the position of a fixed body - Updating the new position of each limb manually, attempting to take into account physics collisions. Then stepping the physics after the animation to allow for environment interaction. Each of these methods have their distinct advantages and disadvantages. Physics based movement Advantages: Possibly more natural/realistic movement Better interaction with game objects as force applying to objects colliding with characters would be calculated for me. No need to convert to dynamic bodies when reacting to projectiles/death/fighting. Disadvantages: Possible difficulty in calculating correct amount of force to move a limb a certain distance at a constant rate. Underlying character balance system would need to be created that would need to be robust enough to prevent characters falling over at the touch of a feather. Added code complexity and processing time for the above. Static Object movement Advantages: Easy to interpolate movement of limbs between game steps Moving limbs is as simple as applying a rotation to the skeleton bone. Greater control over limbs, wont need to worry about characters falling over as all animation would be pre-defined. Disadvantages: Possible unnatural movement (Depends entirely on my animation skills!) Bad physics collision reactions with physics engine (Dynamic bodies simply slide out of the way of static objects) Need to calculate collisions with physics objects and my limbs myself and apply directional forces to them. Hard to account for slopes/stairs/non standard planes when animating walking/running animations. Need to convert objects to dynamic when reacting to projectile/fighting/death physics objects. The Question! As you can see, i have thought about this extensively, i have also had Google into physics based animation and have found mostly dissertation papers! Which is filling me with sense that it may a lot more advanced than my mathematics skills. My question is mostly subjective based on my findings above/any experience you may have: Which of the above methods should i use when creating my game? I am willing to spend the time to get a physics solution working if you think it would be possible. In the end i want to provide the most satisfying experience for the gamer, as well as a robust and dynamic system i can use to animate pretty much anything i need.

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• Compute directional light frustum from view furstum points and light direction

  - by Fabian

  I'm working on a friends engine project and my task is to construct a new frustum from the light direction that overlaps the view frustum and possible shadow casters. The project already has a function that creates a frustum for this but its way to big and includes way to many casters (shadows) which can't be seen in the view frustum. Now the only parameter of this function are the normalized light direction vector and a view class which lets me extract the 8 view frustum points in world space. I don't have any additional infos about the scene. I have read some of the related Questions here but non seem to fit very well to my problem as they often just point to cascaded shadow maps. Sadly i can't use DX or openGl functions directly because this engine has a dedicated math library. From what i've read so far the steps are: Transform view frustum points into light space and find min/max x and y values (or sometimes minima and maxima of all three axis) and create a AABB using the min/max vectors. But what comes after this step? How do i transform this new AABB back to world space? What i've done so far: CVector3 Points[8], MinLight = CVector3(FLT_MAX), MaxLight = CVector3(FLT_MAX); for(int i = 0; i<8;++i){ Points[i] = Points[i] * WorldToShadowMapMatrix; MinLight = Math::Min(Points[i],MinLight); MaxLight = Math::Max(Points[i],MaxLight); } AABox box(MinLight,MaxLight); I don't think this is the right way to do it. The near plain probably has to extend into the direction of the light source to include potentional shadow casters. I've read the Microsoft article about cascaded shadow maps http://msdn.microsoft.com/en-us/library/windows/desktop/ee416307%28v=vs.85%29.aspx which also includes some sample code. But they seem to use the scenes AABB to determine the near and far plane which I can't since i cant access this information from the funtion I'm working in. Could you guys please link some example code which shows the calculation of such frustum? Thanks in advance! Additional questio: is there a way to construct a WorldToFrustum matrix that represents the above transformation?

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• Thank you Geeks With Blogs for letting me join your community!

  - by GreeNTUG

  First, a link to the blog I can no longer edit because Office Live blew away my digital identity and so I can no longer log into it (the source of a loooong blog about protecting your digital identity sometime when I have more time and after it has played out to the end) http://greentug.spaces.live.com/ The following are the communities I participate in: Green & Sustainability.  I run a virtual user group on Green and Sustainability as it relates to developers and software architects.  It was located at greentug.groups.live.com, and we will need to find a new digital location for it, because I am locked out of that site as well. BizSpark Tampa Bay:  I run a BizSpark group for Microsoft technologists (meetup.com, search for BizSpark Tampa Bay) and speak at Code Camps about "No Better Time to Start Your Own Tech Business".  The meetup group facilitates a balanced presentation that is respectful to anyone wanting to start their own business, whether part-time or full-time, whether micro (just you), sustainable (grow to 2-25-ish, self-funded), high growth (get venture capital or other funding, grow it, sell it within 5 years, do it again), or hybrid (the new model going forward).  It is an "action" group, with assignments and homework if you want to get the most out of it.   At the end of a year you will either have your business on the path to where you want it to be, or you will know the steps you need to do to get it there. Women in Technology Have been participating in the Women in Technology community since 2008, my main interests in this area are mentoring women in the workplace to have them believe they can become geeks and double their income, and to mentor them with respect to starting and running their own business. Access 2010/SharePoint 2010.  This is a game-changer with respect to the Access community (the ap both devs and IT Pros love to hate, the other a-word that's not a fruit).  I conducted Lunch n Learns and Brunch n Learns around this topic before the Office 2010/SharePoint 2010 launch, and spoke on the topic at SharePoint Saturday Tampa in Nov 2009. Interested in learning more about: Using Silverlight HD Streaming out in the non-technical world (horses and equestrian sport).  Migrating to Access Web Services and VB .Net from VBA (see the Access 2010/SharePoint 2010 interest above) Windows Phone 7!  Exciting opportunities both for Green and Sustainability and for my "day job" of Environmental, Health & Safety (EHS). My day job is Environmental, Health & Safetey (EHS) consulting and software solutions, where that interfaces with the developer world is with respect to opportunities around Green and Sustainability, The SmartGrid and Juval Lowy's EnergyNet, both of which will require a lot of technology and software to make them work, The new Microsoft Partner competency for "Digital Home", and The Y2K kind of deadline around how managing chemicals in ERP systems is changing because of Global Harmonization, which hits the EU with a hard deadline on 11/30/10 (yes, this year), and hits the USA about 15 months later. Hope you enjoy my contributions to the digital geek community, and feel free to email me, [email protected] (the email leftover after my digital identity was blown away), and [email protected] (this one could go away at some future point) Best, Kathy Malone

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• WinMo&rsquo;s Demise: Notifying Next of &ldquo;Kin&rdquo;

  - by andrewbrust

  This past Monday, April 12th, Visual Studio 2010 was launched.  And on that same day, Microsoft also launched a new line of  mobile phone handsets, called Kin.  The two product launches are actually connected, but only by what they do not have in common, and what they commonly lack. On the former point: VS 2010 had released to manufacturing a couple weeks prior to its launch.  The Kin phones, meanwhile are not yet available.  We don’t even know what they will cost.  (And I think cost will be a major factor in Kin’s success…I told ChannelWeb’s Yara Souza so in this article). What do the two products both lack? Simple: Windows Mobile 6.x. For example, Kin seems to be based on the same platform as Windows Phone 7 (albeit a subset).  And VS 2010 does not support .NET Compact Framework development, which means no .NET development support for WinMo 6.x and earlier. So I guess April 12th marks Windows Phone “clean slate day.”  If you want to develop for the old phone platform, you will need to use the old version of Visual Studio (i.e. 2008).  Luckily VS 2010 and 2008 can be installed side-by-side.  But I doubt that’s much consolation to developers who still target WinMo 6.5 and earlier. Remember, WinMo isn’t just about the phone.  There are all sorts of non-telephony mobile devices, including ruggedized Pocket PC-style instruments, bar code readers and shop-floor-deployed units that don’t run Windows Phone 7 and couldn’t, even if they wanted to. Where will developers in these markets go?  I would guess some will stick with WinMo 6.x and earlier, until Windows Phone 7 can handle their workloads, assuming that does indeed happen.  Others will likely go to Google’s Android platform. For OEMs and developers who need a customizable mobile software stack, Android is turning out to be out-WinMo-ing WinMo.  As I wrote in this post, Google took Microsoft’s model (minus the licensing fees) and combined it with a modern SmartPhone feature set (rather than a late 90s/early oughts PDA paradigm), to great success.  You might say Google embraced and extended. You might also say Microsoft shunned and withdrew.

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• Tuxedo Load Balancing

  - by Todd Little

  A question I often receive is how does Tuxedo perform load balancing.  This is often asked by customers that see an imbalance in the number of requests handled by servers offering a specific service. First of all let me say that Tuxedo really does load or request optimization instead of load balancing.  What I mean by that is that Tuxedo doesn't attempt to ensure that all servers offering a specific service get the same number of requests, but instead attempts to ensure that requests are processed in the least amount of time.   Simple round robin "load balancing" can be employed to ensure that all servers for a particular service are given the same number of requests.  But the question I ask is, "to what benefit"?  Instead Tuxedo scans the queues (which may or may not correspond to servers based upon SSSQ - Single Server Single Queue or MSSQ - Multiple Server Single Queue) to determine on which queue a request should be placed.  The scan is always performed in the same order and during the scan if a queue is empty the request is immediately placed on that queue and request routing is done.  However, should all the queues be busy, meaning that requests are currently being processed, Tuxedo chooses the queue with the least amount of "work" queued to it where work is the sum of all the requests queued weighted by their "load" value as defined in the UBBCONFIG file.  What this means is that under light loads, only the first few queues (servers) process all the requests as an empty queue is often found before reaching the end of the scan.  Thus the first few servers in the queue handle most of the requests.  While this sounds non-optimal, in fact it capitalizes on the underlying operating systems and hardware behavior to produce the best possible performance.  Round Robin scheduling would spread the requests across all the available servers and thus require all of them to be in memory, and likely not share much in the way of hardware or memory caches.  Tuxedo's system maximizes the various caches and thus optimizes overall performance.  Hopefully this makes sense and now explains why you may see a few servers handling most of the requests.  Under heavy load, meaning enough load to keep all servers that can handle a request busy, you should see a relatively equal number of requests processed.  Next post I'll try and cover how this applies to servers in a clustered (MP) environment because the load balancing there is a little more complicated. Regards,Todd LittleOracle Tuxedo Chief Architect

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• How to disable proxy requests once a server has been added to spammers "open proxy" list?

  - by Matt

  Hello all, I've just started in a new company, and have been going over the setup of their Apache webserver conf files... only to find that they've had their apache servers set up as open proxies available to all the world for the last two months. I've already set ProxyRequests Off in the httpd.conf file and restarted the web server, but the access log file is still growing at a horrendous rate (about a gig a day). I noticed that another question was posted on here about this (http://serverfault.com/questions/63715/apache-hit-with-proxy-request), but their access log was supposedly returning 404 errors, while mine appears to be returning 403 and 404 codes... Is this correct? Here are a few lines out of my access log: 87.118.118.124 - - [16/Mar/2010:10:56:36 -0400] "GET http://www.c5interlude.ru/torrent/viewtopic.php?p=2501 HTTP/1.0" 404 219 "http://www.c5interlude.ru/torrent/viewtopic.php?p=2501" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; .NET CLR 1.1.4322)" 117.41.184.27 - - [16/Mar/2010:10:56:36 -0400] "GET http://ad.xtendmedia.com/st?ad_type=iframe&ad_size=300x250&section=790074 HTTP/1.0" 404 200 "http://www.newbiegamer.com" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.0; Alexa Toolbar)" 122.224.55.222 - - [16/Mar/2010:10:56:36 -0400] "GET http://www.188woool.net/\xb4\xf3\xd4\xcb\xb4\xab\xca\xc0.rar HTTP/1.1" 403 214 "http://www.188woool.net/\xb4\xf3\xd4\xcb\xb4\xab\xca\xc0.rar" "Mozilla/4.0" 58.55.21.40 - - [16/Mar/2010:10:56:36 -0400] "GET http://www.cpx24.com/ad1.js HTTP/1.0" 404 204 "http://thebighits.com/?id=aibux" "Mozilla/4.0 (compatible; MSIE 5.01; Windows NT 5.0)" 122.226.223.188 - - [16/Mar/2010:10:56:36 -0400] "GET http://ad.reduxmedia.com/st?ad_type=iframe&ad_size=160x600&section=798636 HTTP/1.0" 404 200 "http://www.gvvu.com" "Mozilla/4.0 (compatible; MSIE 5.5; AOL 6.0; Windows 98; Win 9x 4.90)" 84.51.109.31 - - [16/Mar/2010:10:56:36 -0400] "GET http://www.kslp.ru/forum/index.php HTTP/1.0" 404 213 "http://www.kslp.ru/forum/index.php" "Mozilla/4.0 (compatible; MSIE 7.0b; Windows NT 6.0 ; .NET CLR 2.0.50215; SL Commerce Client v1.0; Tablet PC 2.0" 122.224.48.49 - - [16/Mar/2010:10:56:36 -0400] "GET http://www1.vip218.com/\xb2\xca\xba\xe7\xb4\xab\xca\xc0.exe HTTP/1.1" 403 214 "http://www1.vip218.com/\xb2\xca\xba\xe7\xb4\xab\xca\xc0.exe" "Mozilla/4.0" 117.41.184.27 - - [16/Mar/2010:10:56:36 -0400] "GET http://ad.xtendmedia.com/st?ad_type=iframe&ad_size=728x90&section=657624 HTTP/1.0" 404 200 "http://www.raiseanimals.com" "Mozilla/4.0 (compatible; MSIE 6.0; Windows 98; Alexa Toolbar)" And my corresponding error log entries: [Tue Mar 16 10:56:36 2010] [error] [client 87.118.118.124] File does not exist: C:/public_html/torrent, referer: http://www.c5interlude.ru/torrent/viewtopic.php?p=2501 [Tue Mar 16 10:56:36 2010] [error] [client 117.41.184.27] File does not exist: C:/public_html/st, referer: http://www.newbiegamer.com [Tue Mar 16 10:56:36 2010] [error] [client 122.224.55.222] (22)Invalid argument: Cannot map GET http://www.188woool.net/\xb4\xf3\xd4\xcb\xb4\xab\xca\xc0.rar HTTP/1.1 to file, referer: http://www.188woool.net/\xb4\xf3\xd4\xcb\xb4\xab\xca\xc0.rar [Tue Mar 16 10:56:36 2010] [error] [client 58.55.21.40] File does not exist: C:/public_html/ad1.js, referer: http://thebighits.com/?id=aibux [Tue Mar 16 10:56:36 2010] [error] [client 122.226.223.188] File does not exist: C:/public_html/st, referer: http://www.gvvu.com [Tue Mar 16 10:56:36 2010] [error] [client 84.51.109.31] File does not exist: C:/public_html/forum, referer: http://www.kslp.ru/forum/index.php [Tue Mar 16 10:56:36 2010] [error] [client 122.224.48.49] (22)Invalid argument: Cannot map GET http://www1.vip218.com/\xb2\xca\xba\xe7\xb4\xab\xca\xc0.exe HTTP/1.1 to file, referer: http://www1.vip218.com/\xb2\xca\xba\xe7\xb4\xab\xca\xc0.exe [Tue Mar 16 10:56:36 2010] [error] [client 117.41.184.27] File does not exist: C:/public_html/st, referer: http://www.raiseanimals.com Does this in fact look like the server is blocking them correctly, and is there anything else that I could do better to cut down on my access log size? (perhaps block these requests from the server completely?) Thanks! Matt

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• 10 tape technology features that make you go hmm.

  - by Karoly Vegh

  A week ago an Oracle/StorageTek Tape Specialist, Christian Vanden Balck, visited Vienna, and agreed to visit customers to do techtalks and update them about the technology boom going around tape. I had the privilege to attend some of his sessions and noted the information and features that took the customers by surprise and made them think. Allow me to share the top 10: I. StorageTek as a brand: StorageTek is one of he strongest names in the Tape field. The brand itself was valued so much by customers that even after Sun Microsystems acquiring StorageTek and the Oracle acquiring Sun the brand lives on with all the Oracle tapelibraries are officially branded StorageTek.See http://www.oracle.com/us/products/servers-storage/storage/tape-storage/overview/index.html II. Disk information density limitations: Disk technology struggles with information density. You haven't seen the disk sizes exploding lately, have you? That's partly because there are physical limits on a disk platter. The size is given, the number of platters is limited, they just can't grow, and are running out of physical area to write to. Now, in a T10000C tape cartridge we have over 1000m long tape. There you go, you have got your physical space and don't need to stuff all that data crammed together. You can write in a reliable pattern, and have space to grow too. III. Oracle has a market share of 62% worldwide in recording head manufacturing. That's right. If you are running LTO drives, with a good chance you rely on StorageTek production. That's two out of three LTO recording heads produced worldwide.  IV. You can store 1 Exabyte data in a single tape library. Yes, an Exabyte. That is 1000 Petabytes. Or, a million Terabytes. A thousand million GigaBytes. You can store that in a stacked StorageTek SL8500 tapelibrary. In one SL8500 you can put 10.000 T10000C cartridges, that store 10TB data (compressed). You can stack 10 of these SL8500s together. Boom. 1000.000 TB.(n.b.: stacking means interconnecting the libraries. Yes, cartridges are moved between the stacked libraries automatically.)  V. EMC: 'Tape doesn't suck after all. We moved on.': Do you remember the infamous 'Tape sucks, move on' Datadomain slogan? Of course they had to put it that way, having only had disk products. But here's a fun fact: on the EMCWorld 2012 there was a major presence of a Tape-tech company - EMC, in a sudden burst of sanity is embracing tape again. VI. The miraculous T10000C: Oracle StorageTek has developed an enterprise-grade tapedrive and cartridge, the T10000C. With awesome numbers: The Cartridge: Native 5TB capacity, 10TB with compression Over a kilometer long tape within the cartridge. And it's locked when unmounted, no rattling of your data.  Replaced the metalparticles datalayer with BaFe (bariumferrite) - metalparticles lose around 7% of magnetism within 30 days. BaFe does not. Yes we employ solid-state physicists doing R&D on demagnetisation in our labs. Can be partitioned, storage tiering within the cartridge!  The Drive: 2GB Cache Encryption implemented in HW - no performance hit 252 MB/s native sustained data rate, beats disk technology by far. Not to mention peak throughput.  Leading the tape while never touching the data side of it, protecting your data physically too Data integritiy checking (CRC recalculation) on tape within the drive without having to read it back to the server reordering data from tape-order, delivering it back in application-order  writing 32 tracks at once, reading them back for CRC check at once VII. You only use 20% of your data on a regular basis. The rest 80% is just lying around for years. On continuously spinning disks. Doubly consuming energy (power+cooling), blocking diskstorage capacity. There is a solution called SAM (Storage Archive Manager) that provides you a filesystem unifying disk and tape, moving data on-demand and for clients transparently between the different storage tiers. You can share these filesystems with NFS or CIFS for clients, and enjoy the low TCO of tape. Tapes don't spin. They sit quietly in their slots, storing 10TB data, using no energy, producing no heat, automounted when a client accesses their data.See: http://www.oracle.com/us/products/servers-storage/storage/storage-software/storage-archive-manager/overview/index.html VIII. HW supported for three decades: Did you know that the original PowderHorn library was released in '87 and has been only discontinued in 2010? That is over two decades of supported operation. Tape libraries are - just like the data carrying on tapecartridges - built for longevity. Oh, and the T10000C cartridge has 30-year archival life for long-term retention.  IX. Tape is easy to manage: Have you heard of Tape Storage Analytics? It is a central graphical tool to summarize, monitor, analyze dataflow, health and performance of drives and libraries, see: http://www.oracle.com/us/products/servers-storage/storage/tape-storage/tape-analytics/overview/index.html X. The next generation: The T10000B drives were able to reuse the T10000A cartridges and write on them even more data. On the same cartridges. We call this investment protection, and this is very important for Oracle for the future too. We usually support two generations of cartridges together. The current drive is a T10000C. (...I know I promised to enlist 10, but I got still two more I really want to mention. Allow me to work around the problem: ) X++. The TallBots, the robots moving around the cartridges in the StorageTek library from tapeslots to the drives are cableless. Cables, belts, chains running to moving parts in a library cause maintenance downtimes. So StorageTek eliminated them. The TallBots get power, commands, even firmwareupgrades through the rails they are running on. Also, the TallBots don't just hook'n'pull the tapes out of their slots, they actually grip'n'lift them out. No friction, no scratches, no zillion little plastic particles floating around in the library, in the drives, on your data. (X++)++: Tape beats SSDs and Disks. In terms of throughput (252 MB/s), in terms of TCO: disks cause around 290x more power and cooling, in terms of capacity: 10TB on a single media and soon more.  So... do you need to store large amounts of data? Are you legally bound to archive it for dozens of years? Would you benefit from automatic storage tiering? Have you got large mediachunks to be streamed at times? Have you got power and cooling issues in the growing datacenters? Do you find EMC's 180° turn of tape attitude interesting, but appreciate it at the same time? With all that, you aren't alone. The most data on this planet is stored on tape. Tape is coming. Big time.

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• Tellago releases a RESTful API for BizTalk Server business rules

  - by Charles Young

  Jesus Rodriguez has blogged recently on Tellago Devlabs' release of an open source RESTful API for BizTalk Server Business Rules.   This is an excellent addition to the BizTalk ecosystem and I congratulate Tellago on their work.   See http://weblogs.asp.net/gsusx/archive/2011/02/08/tellago-devlabs-a-restful-api-for-biztalk-server-business-rules.aspx   The Microsoft BRE was originally designed to be used as an embedded library in .NET applications. This is reflected in the implementation of the Rules Engine Update (REU) Service which is a TCP/IP service that is hosted by a Windows service running locally on each BizTalk box. The job of the REU is to distribute rules, managed and held in a central database repository, across the various servers in a BizTalk group.   The engine is therefore distributed on each box, rather than exploited behind a central rules service.   This model is all very well, but proves quite restrictive in enterprise environments. The problem is that the BRE can only run legally on licensed BizTalk boxes. Increasingly we need to deliver rules capabilities across a more widely distributed environment. For example, in the project I am working on currently, we need to surface decisioning capabilities for use within WF workflow services running under AppFabric on non-BTS boxes. The BRE does not, currently, offer any centralised rule service facilities out of the box, and hence you have to roll your own (and then run your rules services on BTS boxes which has raised a few eyebrows on my current project, as all other WCF services run on a dedicated server farm ).   Tellago's API addresses this by providing a RESTful API for querying the rules repository and executing rule sets against XML passed in the request payload. As Jesus points out in his post, using a RESTful approach hugely increases the reach of BRE-based decisioning, allowing simple invocation from code written in dynamic languages, mobile devices, etc.   We developed our own SOAP-based general-purpose rules service to handle scenarios such as the one we face on my current project. SOAP is arguably better suited to enterprise service bus environments (please don't 'flame' me - I refuse to engage in the RESTFul vs. SOAP war). For example, on my current project we use claims based authorisation across the entire service bus and use WIF and WS-Federation for this purpose.   We have extended this to the rules service. I can't release the code for commercial reasons :-( but this approach allows us to legally extend the reach of BRE far beyond the confines of the BizTalk boxes on which it runs and to provide general purpose decisioning capabilities on the bus.   So, well done Tellago.   I haven't had a chance to play with the API yet, but am looking forward to doing so.

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• Looking for tips on managing complexity with SCM repositories

  - by Philip Regan

  I am a solo developer in my department and I have a lot of individual projects, all created and managed by me. I started using SVN at ProjectLocker via Versions on the Mac a couple years ago when the variety of projects started getting unwieldy. Scenario 1: Now I have a process that is of reasonable complexity it can be broken up into multiple smaller applications and they all share files. In one phase, there is a single shared file—a constants file—that is shared between a Cocoa app and an iPhone app framework. In the second phase, the iPhone app framework will be used to create individual apps of the same ilk—controller classes and what not will all be the same—but with different content in each. The problem that I am running across is that the file in the first phase is in one repository with the application that started it, and the app framework is in a second, separate repository. Scenario 2: I have another application framework that partially relies on code from an open source project. This is all internal, non-commerical work, but again, the application framework is going to be used to create a variety of unique products and processes. So, now I have an internally managed repository and an externally managed one out of my control. I make little changes to the open source code to meet the needs of my framework when there is an update I download, but I never commit back into the external repository (though, now that I think about it, I don't think I'm committing it to mine either. Oops). The Problem I have all of this set up on my production Mac quite nicely, but duplicating and subsequently maintaining that environment on my laptop has been challenging. For Scenario 1, I've thought of merging these two projects together into the same repository because they are, for all intents and purposes inextricably linked. But, Scenario 2, I think I'm stuck just managing files as best I can. The Question I'm wondering if anyone has any tips on how to manage either of these situations, as well as other complex SCM scenarios when it comes to linking various files from various repositories together. My familiarity with SVN only comes from my work with Versions. It's been great, but I'm a little out of my depth here.

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• TechEd 2010 Day Three: The Database Designer (Isn't)

  - by BuckWoody

  Yesterday at TechEd 2010 here in New Orleans I worked the front-booth, answering general SQL Server questions for the masses. I was actually a little surprised to find most of the questions I got were from folks that wanted to know more about Stream Insight and Master Data Services. In past conferences I've been asked a lot of "free consulting" questions, about problems folks have had from older products. I don't mind that a bit - in fact, I'm always happy to help in any way I can. But this time people are really interested in the new features in the product, and I like that they are thinking ahead, not just having to solve problems in production. My presentation was on "Database Design in an Hour". We had the usual fun, and SideShow Bob made an appearance - I kid you not. The guy in the back of the room looked just like Sideshow Bob, so I quickly held a "bes thair" contest, and he won. Duing the presentation, I explain the tools you can use to design databases. I also explain that the "Database Designer" tool in SQL Server Management Studio (SSMS) isn't truly a desinger - it uses non-standard notation, doesn't have a meta-data dictionary, and worst of all, it works at the physical level. In other words, whatever you do in SSMS will automatically change the field/table/relationship structures in the database. We fixed this in SSMS 2008 and higher by adding an option to block that, but the tool is not a good design function nonetheless. To be fair, no one I know of at Microsoft recommends that it is - but I was shocked to hear so many developers in the room defending it as a good tool. I think the main issue for someone who doesn't have to work with Relational Systems a great deal is that it can be difficult to figure out Foreign Keys. The syntax makes them look "backwards", so it's just easier to grab a field and place it on the table you want to point to. There are options. You can download a couple of free tools (CA has a community edition of ER-WIN, Quest has one, and Embarcadero also has one) and if you design more than one or two databases a year, it may be worth buying a true design tool. For years I used Visio, but we changed it so that it doesn't forward-engineer (create the DDL) any more, so it isn't a true design tool either. So investigate those free and not-so-free tools. You'll find they help you in your job - but stay away from the Database Designer in SSMS. Or I'll send Sideshow Bob over there to straighten you out. Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

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• SSAS Tabular Workshop online and other upcoming dates (and updates!) #ssas #tabular

  - by Marco Russo (SQLBI)

  After many conferences and travels, this summer I had some time to write and prepare new sessions for the next wave of conferences. In reality I am just doing that, even if I already restarted traveling for consulting and training. So expect new content about DAX and Tabular coming in the next months! Starting to see real customer adopting Tabular is showing many new challenges and there is still a lot to learn and to create. If you still didn’t started working on Tabular, well, you should. As I always say, as a BI developer you should be able to choose between Tabular and Multidimensional, and in order to do that you should know both of them! One thing that I don’t like very much about marketing is that “Tabular is simpler”, because it’s often translated in “Tabular is for simple projects” when this last statement is not true. Actually, I see a lot of good reasons to adopt Tabular in complex data models, especially in non-traditional scenarios. I know, this is because I love to understand what are the actual limits of a technology, and I’m learning that there is simple a lot of space of improvement also for Tabular. It’s already fast, but it could be faster! How can you start? Well, first of all, by reading our book. Then, by attending to our SSAS Tabular workshop. There is an online edition of the workshop on September 3-4, 2012 (hurry up if you want to register), and there are already several dates planned for the next months (and others will be added soon!). And, of course, by installing SQL Server 2012 and trying to create models over your databases. If you are too lazy, just start with PowerPivot. As soon as you start working with Tabular or PowerPivot, you will see that there is one important skill you need: learning DAX. In the next few days I should publish an article that I’m finishing these days about best practices using SUMMARIZE and ADDCOLUMNS. If only someone published this article one year ago, I would have saved many hours of my life. But, you know, flight manuals are written in blood… and someone has to write! Stay tuned.

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• Design pattern for an ASP.NET project using Entity Framework

  - by MPelletier

  I'm building a website in ASP.NET (Web Forms) on top of an engine with business rules (which basically resides in a separate DLL), connected to a database mapped with Entity Framework (in a 3rd, separate project). I designed the Engine first, which has an Entity Framework context, and then went on to work on the website, which presents various reports. I believe I made a terrible design mistake in that the website has its own context (which sounded normal at first). I present this mockup of the engine and a report page's code behind: Engine (in separate DLL): public Engine { DatabaseEntities _engineContext; public Engine() { // Connection string and procedure managed in DB layer _engineContext = DatabaseEntities.Connect(); } public ChangeSomeEntity(SomeEntity someEntity, int newValue) { //Suppose there's some validation too, non trivial stuff SomeEntity.Value = newValue; _engineContext.SaveChanges(); } } And report: public partial class MyReport : Page { Engine _engine; DatabaseEntities _webpageContext; public MyReport() { _engine = new Engine(); _databaseContext = DatabaseEntities.Connect(); } public void ChangeSomeEntityButton_Clicked(object sender, EventArgs e) { SomeEntity someEntity; //Wrong way: //Get the entity from the webpage context someEntity = _webpageContext.SomeEntities.Single(s => s.Id == SomeEntityId); //Send the entity from _webpageContext to the engine _engine.ChangeSomeEntity(someEntity, SomeEntityNewValue); // <- oops, conflict of context //Right(?) way: //Get the entity from the engine context someEntity = _engine.GetSomeEntity(SomeEntityId); //undefined above //Send the entity from the engine's context to the engine _engine.ChangeSomeEntity(someEntity, SomeEntityNewValue); // <- oops, conflict of context } } Because the webpage has its own context, giving the Engine an entity from a different context will cause an error. I happen to know not to do that, to only give the Engine entities from its own context. But this is a very error-prone design. I see the error of my ways now. I just don't know the right path. I'm considering: Creating the connection in the Engine and passing it off to the webpage. Always instantiate an Engine, make its context accessible from a property, sharing it. Possible problems: other conflicts? Slow? Concurrency issues if I want to expand to AJAX? Creating the connection from the webpage and passing it off to the Engine (I believe that's dependency injection?) Only talking through ID's. Creates redundancy, not always practical, sounds archaic. But at the same time, I already recuperate stuff from the page as ID's that I need to fetch anyways. What would be best compromise here for safety, ease-of-use and understanding, stability, and speed?

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• How to implement a simple bullet trajectory

  - by AirieFenix

  I searched and searched and although it's a fair simple question, I don't find the proper answer but general ideas (which I already have). I have a top-down game and I want to implement a gun which shoots bullets that follow a simple path (no physics nor change of trajectory, just go from A to B thing). a: vector of the position of the gun/player. b: vector of the mouse position (cross-hair). w: the vector of the bullet's trajectory. So, w=b-a. And the position of the bullet = [x=x0+speed*time*normalized w.x , y=y0+speed*time * normalized w.y]. I have the constructor: public Shot(int shipX, int shipY, int mouseX, int mouseY) { //I get mouse with Gdx.input.getX()/getY() ... this.shotTime = TimeUtils.millis(); this.posX = shipX; this.posY = shipY; //I used aVector = aVector.nor() here before but for some reason didn't work float tmp = (float) (Math.pow(mouseX-shipX, 2) + Math.pow(mouseY-shipY, 2)); tmp = (float) Math.sqrt(Math.abs(tmp)); this.vecX = (mouseX-shipX)/tmp; this.vecY = (mouseY-shipY)/tmp; } And here I update the position and draw the shot: public void drawShot(SpriteBatch batch) { this.lifeTime = TimeUtils.millis() - this.shotTime; //position = positionBefore + v*t this.posX = this.posX + this.vecX*this.lifeTime*speed*Gdx.graphics.getDeltaTime(); this.posY = this.posY + this.vecY*this.lifeTime*speed*Gdx.graphics.getDeltaTime(); ... } Now, the behavior of the bullet seems very awkward, not going exactly where my mouse is (it's like the mouse is 30px off) and with a random speed. I know I probably need to open the old algebra book from college but I'd like somebody says if I'm in the right direction (or points me to it); if it's a calculation problem, a code problem or both. Also, is it possible that Gdx.input.getX() gives me non-precise position? Because when I draw the cross-hair it also draws off the cursor position. Sorry for the long post and sorry if it's a very basic question. Thanks!

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• What are the default mount settings for mount / fstab?

  - by John Craick

  What are the default mounting options for a non root partition ? The man entry for mount says ... defaults - use default options: rw, suid, dev, exec, auto, nouser, and async. ... so that might be what we expect to see. But, unless I'm missing something, that's not what happens. I have an ext3 partition labelled "NewHome20G" which is seen as /dev/sdc6 by the system. This we can see from ... root@john-pc1204:~# blkid | grep NewHome20G /dev/sdc6: LABEL="NewHome20G" UUID="d024bad5-906c-46c0-b7d4-812daf2c9628" TYPE="ext3" I have an entry in fstab as follows ... root@john-pc1204:~# cat /etc/fstab | grep NewHome LABEL=NewHome20G /media/NewHome20G ext3 rw,nosuid,nodev,exec,users 0 2 Note the option settings that are specified in that fstab line. Now I look at how the partition is actually mounted after boot up ... root@john-pc1204:~# mount -l | grep sdc6 /dev/sdc6 on /media/NewHome20G type ext3 (rw,noexec,nosuid,nodev) [NewHome20G] ... so, when the filesystem gets mounted the exec & users options I specified seem to have been ignored. Just to be sure, I unmount sdc6, remount it and look at the mount options again ... root@john-pc1204:~# umount /dev/sdc6 root@john-pc1204:~# mount /dev/sdc6 root@john-pc1204:~# mount -l | grep sdc6 /dev/sdc6 on /media/NewHome20G type ext3 (rw,noexec,nosuid,nodev) [NewHome20G] .... same result Now I unmount the partition again, remount it specifying the exec option and look at the result ... root@john-pc1204:~# umount /dev/sdc6 root@john-pc1204:~# mount /dev/sdc6 -o exec root@john-pc1204:~# mount -l | grep sdc6 /dev/sdc6 on /media/NewHome20G type ext3 (rw,nosuid,nodev) [NewHome20G] ... and here the exec option has finally taken effect and the noexec setting has vanished. Just for interest, I re-mount the partition with the defaults option root@john-pc1204:~# umount /dev/sdc6 root@john-pc1204:~# mount /dev/sdc6 -o defaults root@john-pc1204:~# mount -l | grep sdc6 /dev/sdc6 on /media/NewHome20G type ext3 (rw,noexec,nosuid,nodev) [NewHome20G] The noexec is back, so it looks very like rw,noexec,nosuid,nodev are the default options which is NOT what man says. Why does this matter ? I have a folder full of useful scripts stored on a data disk. Because that disk is mounted noexec those scripts won't run, even though they have all been set with chmod 777. I can work round this in several ways but it's disappointing that the man entry seems to be wrong. Have I missed something obvious here or have the default options in Ubuntu changed from what they were a few versions ago ?

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• What source code organization approach helps improve modularity and API/Implementation separation?

  - by Berin Loritsch

  Few languages are as restrictive as Java with file naming standards and project structure. In that language, the file name must match the public class declared in the file, and the file must live in a directory structure matching the class package. I have mixed feelings about that approach. While I never have to guess where a file lives, there's still a lot of empty directories and artificial constraints. There's several languages that define everything about a class in one file, at least by convention. C#, Python (I think), Ruby, Erlang, etc. The commonality in most these languages is that they are object oriented, although that statement can probably be rebuffed (there is one non-OO language in the list already). Finally, there's quite a few languages mostly in the C family that have a separate header and implementation file. For C I think this makes sense, because it is one of the few ways to separate the API interface from implementations. With C it seems that feature is used to promote modularity. Yet, with C++ the way header and implementation files are split seems rather forced. You don't get the same clean API separation that you do with C, and you are forced to include some private details in the header you would rather keep only in the implementation. There's quite a few languages that have a concept that overlaps with interfaces like Java, C#, Go, etc. Some languages use what feels like a hack to provide the same concept like C# using pure virtual abstract classes. Still others don't really have an interface concept and rely on "duck" typing--for example Ruby. Ruby has modules, but those are more along the lines of mixing in behaviors to a class than they are for defining how to interact with a class. In OO terms, interfaces are a powerful way to provide separation between an API client and an API implementation. So to hurry up and ask the question, from a personal experience point of view: Does separation of header and implementation help you write more modular code, or does it get in the way? (it helps to specify the language you are referring to) Does the strict file name to class name scheme of Java help maintainability, or is it unnecessary structure for structure's sake? What would you propose to promote good API/Implementation separation and project maintenance, how would you prefer to do it?

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• SQL SERVER – A Brief Note on SET TEXTSIZE

  - by pinaldave

  Here is a small conversation I received. I thought though an old topic, indeed a thought provoking for the moment. Question: Is there any difference between LEFT function and SET TEXTSIZE? I really like this small but interesting question. The question does not specify the difference between usage or performance. Anyway we will quickly take a look at how TEXTSIZE works. You can run the following script to see how LEFT and SET TEXTSIZE works. USE TempDB GO -- Create TestTable CREATE TABLE MyTable (ID INT, MyText VARCHAR(MAX)) GO INSERT MyTable (ID, MyText) VALUES(1, REPLICATE('1234567890', 100)) GO -- Select Data SELECT ID, MyText FROM MyTable GO -- Using Left SELECT ID, LEFT(MyText, 10) MyText FROM MyTable GO -- Set TextSize SET TEXTSIZE 10; SELECT ID, MyText FROM MyTable; SET TEXTSIZE 2147483647 GO -- Clean up DROP TABLE MyTable GO Now let us see the usage result which we receive from both of the example. If you are going to ask what you should do – I really do not know. I can tell you where I will use either of the same. LEFT seems to be easy to use but again if you like to do extra work related to SET TEXTSIZE go for it. Here is how I will use SET TEXTSIZE. If I am selecting data from in my SSMS for testing or any other non production related work from a large table which has lots of columns with varchar data, I will consider using this statement to reduce the amount of the data which is retrieved in the result set. In simple word, for testing purpose I will use it. On the production server, there should be a specific reason to use the same. Here is my candid opinion – I do not think they can be directly comparable even though both of them give the exact same result. LEFT is applicable only on the column of a single SELECT statement. where it is used but it SET TEXTSIZE applies to all the columns in the SELECT and follow up SELECT statements till the SET TEXTSIZE is not modified again in the session. Uncomparable! I hope this sample example gives you idea how to use SET TEXTSIZE in your daily use. I would like to know your opinion about how and when do you use this feature. Please leave a comment. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• What are the tradeoffs for using 'partial view models'?

  - by Kenny Evitt

  I've become aware of an itch due to some non-DRY code pertaining to view model classes in an (ASP.NET) MVC web application and I'm thinking of scratching my itch by organizing code in various 'partial view model' classes. By partial-view-model, I'm referring to a class like a view model class in an analogous way to how partial views are like views, i.e. a way to encapsulate common info and behavior. To strengthen the 'analogy', and to aid in visually organizing the code in my IDE, I was thinking of naming the partial-view-model classes with a _ prefix, e.g. _ParentItemViewModel. As a slightly more concrete example of why I'm thinking along these lines, imagine that I have a domain-model-entity class ParentItem and the user-friendly descriptive text that identifies these items to users is complex enough that I'd like to encapsulate that code in a method in a _ParentItemViewModel class, for which I can then include an object or a collection of objects of that class in all the view model classes for all the views that need to include a reference to a parent item, e.g. ChildItemViewModel can have a ParentItem property of the _ParentItemViewModel class type, so that in my ChildItemView view, I can use @Model.ParentItem.UserFriendlyDescription as desired, like breadcrumbs, links, etc. Edited 2014-02-06 09:56 -05 As a second example, imagine that I have entity classes SomeKindOfBatch, SomeKindOfBatchDetail, and SomeKindOfBatchDetailEvent, and a view model class and at least one view for each of those entities. Also, the example application covers a lot more than just some-kind-of-batches, so that it wouldn't really be useful or sensible to include info about a specific some-kind-of-batch in all of the project view model classes. But, like the above example, I have some code, say for generating a string for identifying a some-kind-of-batch in a user-friendly way, and I'd like to be able to use that in several views, say as breadcrumb text or text for a link. As a third example, I'll describe another pattern I'm currently using. I have a Contact entity class, but it's a fat class, with dozens of properties, and at least a dozen references to other fat classes. However, a lot of view model classes need properties for referencing a specific contact and most of those need other properties for collections of contacts, e.g. possible contacts to be referenced for some kind of relationship. Most of these view model classes only need a small fraction of all of the available contact info, basically just an ID and some kind of user-friendly description (i.e. a friendly name). It seems to be pretty useful to have a 'partial view model' class for contacts that all of these other view model classes can use. Maybe I'm just misunderstanding 'view model class' – I understand a view model class as always corresponding to a view. But maybe I'm assuming too much.

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• Development-led security vs administration-led security in a software product?

  - by haylem

  There are cases where you have the opportunity, as a developer, to enforce stricter security features and protections on a software, though they could very well be managed at an environmental level (ie, the operating system would take care of it). Where would you say you draw the line, and what elements do you factor in your decision? Concrete Examples User Management is the OS's responsibility Not exactly meant as a security feature, but in a similar case Google Chrome used to not allow separate profiles. The invoked reason (though it now supports multiple profiles for a same OS user) used to be that user management was the operating system's responsibility. Disabling Web-Form Fields A recurrent request I see addressed online is to have auto-completion be disabled on form fields. Auto-completion didn't exist in old browsers, and was a welcome feature at the time it was introduced for people who needed to fill in forms often. But it also brought in some security concerns, and so some browsers started to implement, on top of the (obviously needed) setting in their own preference/customization panel, an autocomplete attribute for form or input fields. And this has now been introduced into the upcoming HTML5 standard. For browsers that do not listen to this attribute, strange hacks* are offered, like generating unique IDs and names for fields to avoid them from being suggested in future forms (which comes with another herd of issues, like polluting your local auto-fill cache and not preventing a password from being stored in it, but instead probably duplicating its occurences). In this particular case, and others, I'd argue that this is a user setting and that it's the user's desire and the user's responsibility to enable or disable auto-fill (by disabling the feature altogether). And if it is based on an internal policy and security requirement in a corporate environment, then substitute the user for the administrator in the above. I assume it could be counter-argued that the user may want to access non-critical applications (or sites) with this handy feature enabled, and critical applications with this feature disabled. But then I'd think that's what security zones are for (in some browsers), or the sign that you need a more secure (and dedicated) environment / account to use these applications. * I obviously don't deny the ingeniosity of the people who were forced to find workarounds, just the necessity of said workarounds. Questions That was a tad long-winded, so I guess my questions are: Would you in general consider it to be the application's (hence, the developer's) responsiblity? Where do you draw the line, if not in the "general" case?

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• Win7 is not a tablet OS, no matter what the boys in Redmond think.

  - by John Conwell

  Despite what execs at Microsoft think, Windows 7 is NOT a tablet OS.  Just because you can install some software (or OS) on a device, doesn't mean that device is meant to run that software.  This seems to be the step that the non-engineer execs at Microsoft have seem to not understood.  In order to seamlessly work with a device, the software needs to be designed with that device in mind.  That has been the problem with the Windows PDA platform, the Windows Mobil platform, and now with trying to force fit Windows 7 on a tablet.  Its just not designed for that style of interaction.   Windows is designed to be interacted with via a mouse and keyboard.  In fact, it is brilliant at that.  But, It is NOT designed to be interacted with by your fingers.  And that is why the Windows tablet failed 10 years ago, and why it will fail today.  Its not the hardware's fault like Microsoft claimed 10 years ago.  Its the User Interaction design that failed. And this is why the iPhone and Android OS's work wonderfully on a tablet.  The user interaction was designed for small screens, navigated by big fat fingers.  I love these OS's and how I interact with them.  And when I play with a touch screen Windows 7 device, I am feel like I'm playing with a brittle wana-be.  And its not the hardware's fault.  The touchscreen is very responsive.  I actually like the hardware.  But the OS and the software are just not designed to be interacted with, with my big fat fingers.  In order to be successful, Microsoft needs to start from scratch, and build a platform AND SOFTWARE specifically for use by fingers.  Thats why everyone was so excited when they though Microsoft was going to release the Courier tablet.  Because it looked like a totally different platform.  Something that might actually work.  But Windows 7...I hate to burst your bubble, but you are not a touch platform.

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• NFS server generating "invalid extent" on EXT4 system disk?

  - by Stephen Winnall

  I have a server running Xen 4.1 with Oneiric in the dom0 and each of the 4 domUs. The system disks of the domUs are LVM2 volumes built on top of an mdadm RAID1. All the domU system disks are EXT4 and are created using snapshots of the same original template. 3 of them run perfectly, but one (called s-ub-02) keeps on being remounted read-only. A subsequent e2fsck results in a single "invalid extent" diagnosis: e2fsck 1.41.14 (22-Dec-2010) /dev/domu/s-ub-02-root contains a file system with errors, check forced. Pass 1: Checking inodes, blocks, and sizes Inode 525418 has an invalid extent (logical block 8959, invalid physical block 0, len 0) Clear<y>? yes Pass 2: Checking directory structure Pass 3: Checking directory connectivity Pass 4: Checking reference counts Pass 5: Checking group summary information /dev/domu/s-ub-02-root: 77757/655360 files (0.3% non-contiguous), 360592/2621440 blocks The console shows typically the following errors for the system disk (xvda2): [101980.903416] EXT4-fs error (device xvda2): ext4_ext_find_extent:732: inode #525418: comm apt-get: bad header/extent: invalid extent entries - magic f30a, entries 12, max 340(340), depth 0(0) [101980.903473] EXT4-fs (xvda2): Remounting filesystem read-only I have created new versions of the system disk. The same thing always happens. This, and the fact that the disk is ultimately on a RAID1, leads me to preclude a hardware disk error. The only obvious distinguishing feature of this domU is the presence of nfs-kernel-server, so I suspect that. Its exports file looks like this: /exports/users 192.168.0.0/255.255.248.0(rw,sync,no_subtree_check) /exports/media/music 192.168.0.0/255.255.248.0(rw,sync,no_subtree_check) /exports/media/pictures 192.168.0.0/255.255.248.0(rw,sync,no_subtree_check) /exports/opt 192.168.0.0/255.255.248.0(rw,sync,no_subtree_check) /exports/users and /exports/opt are LVM2 volumes from the same volume group as the system disk. /exports/media is an EXT2 volume. (There is an issue where clients see /exports/media/pictures as being a read-only volume, which I mention for completeness.) With the exception of the read-only problem, the NFS server appears to work correctly under light load for several hours before the "invalid extent" problem occurs. There are no helpful entries in /var/log. All of a sudden, no more files are written, so you can see when the disk was remounted read-only, but there is no indication of what the cause might be. Can anyone help me with this problem? Steve

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• Is throwing an error in unpredictable subclass-specific circumstances a violation of LSP?

  - by Motti Strom

  Say, I wanted to create a Java List<String> (see spec) implementation that uses a complex subsystem, such as a database or file system, for its store so that it becomes a simple persistent collection rather than an basic in-memory one. (We're limiting it specifically to a List of Strings for the purposes of discussion, but it could extended to automatically de-/serialise any object, with some help. We can also provide persistent Sets, Maps and so on in this way too.) So here's a skeleton implementation: class DbBackedList implements List<String> { private DbBackedList() {} /** Returns a list, possibly non-empty */ public static getList() { return new DbBackedList(); } public String get(int index) { return Db.getTable().getRow(i).asString(); // may throw DbExceptions! } // add(String), add(int, String), etc. ... } My problem lies with the fact that the underlying DB API may encounter connection errors that are not specified in the List interface that it should throw. My problem is whether this violates Liskov's Substitution Principle (LSP). Bob Martin actually gives an example of a PersistentSet in his paper on LSP that violates LSP. The difference is that his newly-specified Exception there is determined by the inserted value and so is strengthening the precondition. In my case the connection/read error is unpredictable and due to external factors and so is not technically a new precondition, merely an error of circumstance, perhaps like OutOfMemoryError which can occur even when unspecified. In normal circumstances, the new Error/Exception might never be thrown. (The caller could catch if it is aware of the possibility, just as a memory-restricted Java program might specifically catch OOME.) Is this therefore a valid argument for throwing an extra error and can I still claim to be a valid java.util.List (or pick your SDK/language/collection in general) and not in violation of LSP? If this does indeed violate LSP and thus not practically usable, I have provided two less-palatable alternative solutions as answers that you can comment on, see below. Footnote: Use Cases In the simplest case, the goal is to provide a familiar interface for cases when (say) a database is just being used as a persistent list, and allow regular List operations such as search, subList and iteration. Another, more adventurous, use-case is as a slot-in replacement for libraries that work with basic Lists, e.g if we have a third-party task queue that usually works with a plain List: new TaskWorkQueue(new ArrayList<String>()).start() which is susceptible to losing all it's queue in event of a crash, if we just replace this with: new TaskWorkQueue(new DbBackedList()).start() we get a instant persistence and the ability to share the tasks amongst more than one machine. In either case, we could either handle connection/read exceptions that are thrown, perhaps retrying the connection/read first, or allow them to throw and crash the program (e.g. if we can't change the TaskWorkQueue code).

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• How do I prevent having to log in on 3 separate prompts every time I start my machine?

  - by JC

  Ubuntu 11.04 Natty Narwhal, Ubuntu Classic desktop Each time I start my machine, I have to log in 3 times. I spent a week in IRCFreenode#ubuntu and got nothing but condescension. I've searched on the official Ubuntu fora for similar problems, tried every recommendation, and still get 3 login screens. As a workaround, I have reset login such that I get a login screen at startup, which I'd prefer not to get since this machine is accessible by no one but me, physically. I have gone into System Preferences Passwords and Encryption Keys, set first 'Passwords: default' to 'Default' and unlocked it, and unlocked the 'Passwords: login' key, too. Next, since that changed nothing, I set 'Passwords: login' to 'Default', and checked to make sure it was still unlocked. Again, no change, still get 3 login prompts at startup. I've checked twice to insure that I am the owner of the files; I am. At the suggestion of several people in #ubuntu, I've deleted first one, then the other password key in 'Passwords and Encryption Keys'. Still get 3 login prompts. I changed from the Unity desktop to Ubuntu Classic. While that didn't fix the above problem, it is a much more elegant desktop than Unity, and I'll keep it. From what I've read, this seems to be a Seahorse issue, but beyond that, no one seems to have a solution that works. I'm lost. This shouldn't be this difficult or annoying. I'm trying to help our local Old Time music collective get their machines switched over to Ubuntu in order to save them some money which they can use to promote their DRM-free music. But from what I've seen of Ubuntu so far on my own machine, I can't really recommend that they make this switch. I hope to be proved wrong on that point. But as it stands, if I was out of town or out of country and they ran into a problem, they'd have no way of fixing it as they're all less experienced than even I am. I'm not trying to cast aspersions on Ubuntu or Linux, but it seems pretty clear that KNOWLEDGEABLE, HELPFUL support for Ubuntu is lacking barring any desire on the problem-experiencing-user's part to avoid condescension. Having worked with, and run, several non-profits over the past 20 years, I know that getting volunteers to act professionally can be like herding cats. But an organization's reputation can be denigrated by sarcastic behaviors on the part of those who serve, effectively, as its public face. Thank you all for your help and support. Now...does anyone have a solution to my problem?

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