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• CLR via C# 3rd Edition is out

  - by Abhijeet Patel

  Time for some book news update. CLR via C#, 3rd Edition seems to have been out for a little while now. The book was released in early Feb this year, and needless to say my copy is on it’s way. I can barely wait to dig in and chew on the goodies that one of the best technical authors and software professionals I respect has in store. The 2nd edition of the book was an absolute treat and this edition promises to be no less. Here is a brief description of what’s new and updated from the 2nd edition. Part I – CLR Basics Chapter 1-The CLR’s Execution Model Added about discussion about C#’s /optimize and /debug switches and how they relate to each other. Chapter 2-Building, Packaging, Deploying, and Administering Applications and Types Improved discussion about Win32 manifest information and version resource information. Chapter 3-Shared Assemblies and Strongly Named Assemblies Added discussion of TypeForwardedToAttribute and TypeForwardedFromAttribute. Part II – Designing Types Chapter 4-Type Fundamentals No new topics. Chapter 5-Primitive, Reference, and Value Types Enhanced discussion of checked and unchecked code and added discussion of new BigInteger type. Also added discussion of C# 4.0’s dynamic primitive type. Chapter 6-Type and Member Basics No new topics. Chapter 7-Constants and Fields No new topics. Chapter 8-Methods Added discussion of extension methods and partial methods. Chapter 9-Parameters Added discussion of optional/named parameters and implicitly-typed local variables. Chapter 10-Properties Added discussion of automatically-implemented properties, properties and the Visual Studio debugger, object and collection initializers, anonymous types, the System.Tuple type and the ExpandoObject type. Chapter 11-Events Added discussion of events and thread-safety as well as showing a cool extension method to simplify the raising of an event. Chapter 12-Generics Added discussion of delegate and interface generic type argument variance. Chapter 13-Interfaces No new topics. Part III – Essential Types Chapter 14-Chars, Strings, and Working with Text No new topics. Chapter 15-Enums Added coverage of new Enum and Type methods to access enumerated type instances. Chapter 16-Arrays Added new section on initializing array elements. Chapter 17-Delegates Added discussion of using generic delegates to avoid defining new delegate types. Also added discussion of lambda expressions. Chapter 18-Attributes No new topics. Chapter 19-Nullable Value Types Added discussion on performance. Part IV – CLR Facilities Chapter 20-Exception Handling and State Management This chapter has been completely rewritten. It is now about exception handling and state management. It includes discussions of code contracts and constrained execution regions (CERs). It also includes a new section on trade-offs between writing productive code and reliable code. Chapter 21-Automatic Memory Management Added discussion of C#’s fixed state and how it works to pin objects in the heap. Rewrote the code for weak delegates so you can use them with any class that exposes an event (the class doesn’t have to support weak delegates itself). Added discussion on the new ConditionalWeakTable class, GC Collection modes, Full GC notifications, garbage collection modes and latency modes. I also include a new sample showing how your application can receive notifications whenever Generation 0 or 2 collections occur. Chapter 22-CLR Hosting and AppDomains Added discussion of side-by-side support allowing multiple CLRs to be loaded in a single process. Added section on the performance of using MarshalByRefObject-derived types. Substantially rewrote the section on cross-AppDomain communication. Added section on AppDomain Monitoring and first chance exception notifications. Updated the section on the AppDomainManager class. Chapter 23-Assembly Loading and Reflection Added section on how to deploy a single file with dependent assemblies embedded inside it. Added section comparing reflection invoke vs bind/invoke vs bind/create delegate/invoke vs C#’s dynamic type. Chapter 24-Runtime Serialization This is a whole new chapter that was not in the 2nd Edition. Part V – Threading Chapter 25-Threading Basics Whole new chapter motivating why Windows supports threads, thread overhead, CPU trends, NUMA Architectures, the relationship between CLR threads and Windows threads, the Thread class, reasons to use threads, thread scheduling and priorities, foreground thread vs background threads. Chapter 26-Performing Compute-Bound Asynchronous Operations Whole new chapter explaining the CLR’s thread pool. This chapter covers all the new .NET 4.0 constructs including cooperative cancelation, Tasks, the aralle class, parallel language integrated query, timers, how the thread pool manages its threads, cache lines and false sharing. Chapter 27-Performing I/O-Bound Asynchronous Operations Whole new chapter explaining how Windows performs synchronous and asynchronous I/O operations. Then, I go into the CLR’s Asynchronous Programming Model, my AsyncEnumerator class, the APM and exceptions, Applications and their threading models, implementing a service asynchronously, the APM and Compute-bound operations, APM considerations, I/O request priorities, converting the APM to a Task, the event-based Asynchronous Pattern, programming model soup. Chapter 28-Primitive Thread Synchronization Constructs Whole new chapter discusses class libraries and thread safety, primitive user-mode, kernel-mode constructs, and data alignment. Chapter 29-Hybrid Thread Synchronization Constructs Whole new chapter discussion various hybrid constructs such as ManualResetEventSlim, SemaphoreSlim, CountdownEvent, Barrier, ReaderWriterLock(Slim), OneManyResourceLock, Monitor, 3 ways to solve the double-check locking technique, .NET 4.0’s Lazy and LazyInitializer classes, the condition variable pattern, .NET 4.0’s concurrent collection classes, the ReaderWriterGate and SyncGate classes.

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• How to mix textures in DirectX?

  - by tobsen

  I am new to DirectX development and I am wondering if I am taking the wrong route to achieve the following: I would like to mix three textures which contain transparent areas and some solid areas (Red, Blue, Green). The three textures should blend like shown in this example: How can I achieve that in DirectX (preferably in directx9)? A link or example code would be nice. Update: My rendering method looks like this and I still think I am doing it wrong, because the sprite only shows the last texture (nothing is rendered transparent or blended): void D3DTester::render() { d3ddevice->Clear(0, NULL, D3DCLEAR_TARGET, D3DCOLOR_XRGB(0,0,0), 1.0f, 0); d3ddevice->BeginScene(); d3ddevice->SetRenderState(D3DRS_ALPHABLENDENABLE, TRUE); d3ddevice->SetRenderState(D3DRS_SRCBLEND, D3DBLEND_ONE); d3ddevice->SetRenderState(D3DRS_DESTBLEND, D3DBLEND_ONE); LPD3DXSPRITE sprite=NULL; HRESULT hres = D3DXCreateSprite(d3ddevice, &sprite); if(hres != S_OK) { throw std::exception(); } sprite->Begin(D3DXSPRITE_ALPHABLEND); std::vector<LPDIRECT3DTEXTURE9>::iterator it; for ( it=textures.begin() ; it < textures.end(); it++ ) { sprite->Draw(*it, NULL, NULL, NULL, 0xFFFFFFFF); } sprite->End(); d3ddevice->EndScene(); d3ddevice->Present(NULL, NULL, NULL, NULL); } The resulting image looks like this: But I need it to look like this instead: Update2: I figured out that I have to SetRenderState after I use sprite->Begin(D3DXSPRITE_ALPHABLEND); thanks to the hint by Josh Petrie. However, by using this: sprite->Begin(D3DXSPRITE_ALPHABLEND); d3ddevice->SetRenderState(D3DRS_ALPHABLENDENABLE, TRUE); d3ddevice->SetRenderState(D3DRS_SRCBLEND, D3DBLEND_ONE); d3ddevice->SetRenderState(D3DRS_DESTBLEND, D3DBLEND_ONE); std::vector<LPDIRECT3DTEXTURE9>::iterator it; for ( it=textures.begin() ; it < textures.end(); it++ ) { sprite->Draw(*it, NULL, NULL, NULL, 0xFFFFFFFF); } sprite->End(); The sprites colors are becoming transparent towards the background scene e.g.: if I use d3ddevice->Clear(0, NULL, D3DCLEAR_TARGET, D3DCOLOR_XRGB(0,100,21), 1.0f, 0); the result looks like: Is there any way to avoid that? I would like the sprites be transparent to each other but to be still solid to the background. Update3: After having sombody explained to me, how to do what @LaurentCouvidou and @JoshPetrie suggested, I have a working solution and therfore accept the answer: d3ddevice->BeginScene(); D3DCOLOR white = D3DCOLOR_RGBA((UINT)255, (UINT)255, (UINT)255, 255); D3DCOLOR black = D3DCOLOR_RGBA((UINT)0, (UINT)0, (UINT)0, 255); sprite->Begin(D3DXSPRITE_ALPHABLEND); sprite->Draw(pTextureRed, NULL, NULL, NULL, black); sprite->Draw(pTextureGreen, NULL, NULL, NULL, black); sprite->Draw(pTextureBlue, NULL, NULL, NULL, black); sprite->End(); sprite->Begin(D3DXSPRITE_ALPHABLEND); d3ddevice->SetRenderState(D3DRS_ALPHATESTENABLE, TRUE); d3ddevice->SetRenderState(D3DRS_BLENDOP, D3DBLENDOP_ADD); d3ddevice->SetRenderState(D3DRS_SRCBLEND, D3DBLEND_ONE); d3ddevice->SetRenderState(D3DRS_DESTBLEND, D3DBLEND_ONE); sprite->Draw(pTextureRed, NULL, NULL, NULL, white); sprite->Draw(pTextureGreen, NULL, NULL, NULL, white); sprite->Draw(pTextureBlue, NULL, NULL, NULL, white); sprite->End(); d3ddevice->EndScene(); d3ddevice->Present(NULL, NULL, NULL, NULL);

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• Goto for the Java Programming Language

  - by darcy

  Work on JDK 8 is well-underway, but we thought this late-breaking JEP for another language change for the platform couldn't wait another day before being published. Title: Goto for the Java Programming Language Author: Joseph D. Darcy Organization: Oracle. Created: 2012/04/01 Type: Feature State: Funded Exposure: Open Component: core/lang Scope: SE JSR: 901 MR Discussion: compiler dash dev at openjdk dot java dot net Start: 2012/Q2 Effort: XS Duration: S Template: 1.0 Reviewed-by: Duke Endorsed-by: Edsger Dijkstra Funded-by: Blue Sun Corporation Summary Provide the benefits of the time-testing goto control structure to Java programs. The Java language has a history of adding new control structures over time, the assert statement in 1.4, the enhanced for-loop in 1.5,and try-with-resources in 7. Having support for goto is long-overdue and simple to implement since the JVM already has goto instructions. Success Metrics The goto statement will allow inefficient and verbose recursive algorithms and explicit loops to be replaced with more compact code. The effort will be a success if at least twenty five percent of the JDK's explicit loops are replaced with goto's. Coordination with IDE vendors is expected to help facilitate this goal. Motivation The goto construct offers numerous benefits to the Java platform, from increased expressiveness, to more compact code, to providing new programming paradigms to appeal to a broader demographic. In JDK 8, there is a renewed focus on using the Java platform on embedded devices with more modest resources than desktop or server environments. In such contexts, static and dynamic memory footprint is a concern. One significant component of footprint is the code attribute of class files and certain classes of important algorithms can be expressed more compactly using goto than using other constructs, saving footprint. For example, to implement state machines recursively, some parties have asked for the JVM to support tail calls, that is, to perform a complex transformation with security implications to turn a method call into a goto. Such complicated machinery should not be assumed for an embedded context. A better solution is just to expose to the programmer the desired functionality, goto. The web has familiarized users with a model of traversing links among different HTML pages in a free-form fashion with some state being maintained on the side, such as login credentials, to effect behavior. This is exactly the programming model of goto and code. While in the past this has been derided as leading to "spaghetti code," spaghetti is a tasty and nutritious meal for programmers, unlike quiche. The invokedynamic instruction added by JSR 292 exposes the JVM's linkage operation to programmers. This is a low-level operation that can be leveraged by sophisticated programmers. Likewise, goto is a also a low-level operation that should not be hidden from programmers who can use more efficient idioms. Some may object that goto was consciously excluded from the original design of Java as one of the removed feature from C and C++. However, the designers of the Java programming languages have revisited these removals before. The enum construct was also left out only to be added in JDK 5 and multiple inheritance was left out, only to be added back by the virtual extension method methods of Project Lambda. As a living language, the needs of the growing Java community today should be used to judge what features are needed in the platform tomorrow; the language should not be forever bound by the decisions of the past. Description From its initial version, the JVM has had two instructions for unconditional transfer of control within a method, goto (0xa7) and goto_w (0xc8). The goto_w instruction is used for larger jumps. All versions of the Java language have supported labeled statements; however, only the break and continue statements were able to specify a particular label as a target with the onerous restriction that the label must be lexically enclosing. The grammar addition for the goto statement is: GotoStatement: goto Identifier ; The new goto statement similar to break except that the target label can be anywhere inside the method and the identifier is mandatory. The compiler simply translates the goto statement into one of the JVM goto instructions targeting the right offset in the method. Therefore, adding the goto statement to the platform is only a small effort since existing compiler and JVM functionality is reused. Other language changes to support goto include obvious updates to definite assignment analysis, reachability analysis, and exception analysis. Possible future extensions include a computed goto as found in gcc, which would replace the identifier in the goto statement with an expression having the type of a label. Testing Since goto will be implemented using largely existing facilities, only light levels of testing are needed. Impact Compatibility: Since goto is already a keyword, there are no source compatibility implications. Performance/scalability: Performance will improve with more compact code. JVMs already need to handle irreducible flow graphs since goto is a VM instruction.

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• Why enumerator structs are a really bad idea

  - by Simon Cooper

  If you've ever poked around the .NET class libraries in Reflector, I'm sure you would have noticed that the generic collection classes all have implementations of their IEnumerator as a struct rather than a class. As you will see, this design decision has some rather unfortunate side effects... As is generally known in the .NET world, mutable structs are a Very Bad Idea; and there are several other blogs around explaining this (Eric Lippert's blog post explains the problem quite well). In the BCL, the generic collection enumerators are all mutable structs, as they need to keep track of where they are in the collection. This bit me quite hard when I was coding a wrapper around a LinkedList<int>.Enumerator. It boils down to this code: sealed class EnumeratorWrapper : IEnumerator<int> { private readonly LinkedList<int>.Enumerator m_Enumerator; public EnumeratorWrapper(LinkedList<int> linkedList) { m_Enumerator = linkedList.GetEnumerator(); } public int Current { get { return m_Enumerator.Current; } } object System.Collections.IEnumerator.Current { get { return Current; } } public bool MoveNext() { return m_Enumerator.MoveNext(); } public void Reset() { ((System.Collections.IEnumerator)m_Enumerator).Reset(); } public void Dispose() { m_Enumerator.Dispose(); } } The key line here is the MoveNext method. When I initially coded this, I thought that the call to m_Enumerator.MoveNext() would alter the enumerator state in the m_Enumerator class variable and so the enumeration would proceed in an orderly fashion through the collection. However, when I ran this code it went into an infinite loop - the m_Enumerator.MoveNext() call wasn't actually changing the state in the m_Enumerator variable at all, and my code was looping forever on the first collection element. It was only after disassembling that method that I found out what was going on The MoveNext method above results in the following IL: .method public hidebysig newslot virtual final instance bool MoveNext() cil managed { .maxstack 1 .locals init ( [0] bool CS$1$0000, [1] valuetype [System]System.Collections.Generic.LinkedList`1/Enumerator CS$0$0001) L_0000: nop L_0001: ldarg.0 L_0002: ldfld valuetype [System]System.Collections.Generic.LinkedList`1/Enumerator EnumeratorWrapper::m_Enumerator L_0007: stloc.1 L_0008: ldloca.s CS$0$0001 L_000a: call instance bool [System]System.Collections.Generic.LinkedList`1/Enumerator::MoveNext() L_000f: stloc.0 L_0010: br.s L_0012 L_0012: ldloc.0 L_0013: ret } Here, the important line is 0002 - m_Enumerator is accessed using the ldfld operator, which does the following: Finds the value of a field in the object whose reference is currently on the evaluation stack. So, what the MoveNext method is doing is the following: public bool MoveNext() { LinkedList<int>.Enumerator CS$0$0001 = this.m_Enumerator; bool CS$1$0000 = CS$0$0001.MoveNext(); return CS$1$0000; } The enumerator instance being modified by the call to MoveNext is the one stored in the CS$0$0001 variable on the stack, and not the one in the EnumeratorWrapper class instance. Hence why the state of m_Enumerator wasn't getting updated. Hmm, ok. Well, why is it doing this? If you have a read of Eric Lippert's blog post about this issue, you'll notice he quotes a few sections of the C# spec. In particular, 7.5.4: ...if the field is readonly and the reference occurs outside an instance constructor of the class in which the field is declared, then the result is a value, namely the value of the field I in the object referenced by E. And my m_Enumerator field is readonly! Indeed, if I remove the readonly from the class variable then the problem goes away, and the code works as expected. The IL confirms this: .method public hidebysig newslot virtual final instance bool MoveNext() cil managed { .maxstack 1 .locals init ( [0] bool CS$1$0000) L_0000: nop L_0001: ldarg.0 L_0002: ldflda valuetype [System]System.Collections.Generic.LinkedList`1/Enumerator EnumeratorWrapper::m_Enumerator L_0007: call instance bool [System]System.Collections.Generic.LinkedList`1/Enumerator::MoveNext() L_000c: stloc.0 L_000d: br.s L_000f L_000f: ldloc.0 L_0010: ret } Notice on line 0002, instead of the ldfld we had before, we've got a ldflda, which does this: Finds the address of a field in the object whose reference is currently on the evaluation stack. Instead of loading the value, we're loading the address of the m_Enumerator field. So now the call to MoveNext modifies the enumerator stored in the class rather than on the stack, and everything works as expected. Previously, I had thought enumerator structs were an odd but interesting feature of the BCL that I had used in the past to do linked list slices. However, effects like this only underline how dangerous mutable structs are, and I'm at a loss to explain why the enumerators were implemented as structs in the first place. (interestingly, the SortedList<TKey, TValue> enumerator is a struct but is private, which makes it even more odd - the only way it can be accessed is as a boxed IEnumerator!). I would love to hear people's theories as to why the enumerators are implemented in such a fashion. And bonus points if you can explain why LinkedList<int>.Enumerator.Reset is an explicit implementation but Dispose is implicit... Note to self: never ever ever code a mutable struct.

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• Reference Data Management and Master Data: Are Relation ?

  - by Mala Narasimharajan

  Submitted By:  Rahul Kamath  Oracle Data Relationship Management (DRM) has always been extremely powerful as an Enterprise Master Data Management (MDM) solution that can help manage changes to master data in a way that influences enterprise structure, whether it be mastering chart of accounts to enable financial transformation, or revamping organization structures to drive business transformation and operational efficiencies, or restructuring sales territories to enable equitable distribution of leads to sales teams following the acquisition of new products, or adding additional cost centers to enable fine grain control over expenses. Increasingly, DRM is also being utilized by Oracle customers for reference data management, an emerging solution space that deserves some explanation. What is reference data? How does it relate to Master Data? Reference data is a close cousin of master data. While master data is challenged with problems of unique identification, may be more rapidly changing, requires consensus building across stakeholders and lends structure to business transactions, reference data is simpler, more slowly changing, but has semantic content that is used to categorize or group other information assets – including master data – and gives them contextual value. In fact, the creation of a new master data element may require new reference data to be created. For example, when a European company acquires a US business, chances are that they will now need to adapt their product line taxonomy to include a new category to describe the newly acquired US product line. Further, the cross-border transaction will also result in a revised geo hierarchy. The addition of new products represents changes to master data while changes to product categories and geo hierarchy are examples of reference data changes.1 The following table contains an illustrative list of examples of reference data by type. Reference data types may include types and codes, business taxonomies, complex relationships & cross-domain mappings or standards. Types & Codes Taxonomies Relationships / Mappings Standards Transaction Codes Industry Classification Categories and Codes, e.g., North America Industry Classification System (NAICS) Product / Segment; Product / Geo Calendars (e.g., Gregorian, Fiscal, Manufacturing, Retail, ISO8601) Lookup Tables (e.g., Gender, Marital Status, etc.) Product Categories City à State à Postal Codes Currency Codes (e.g., ISO) Status Codes Sales Territories (e.g., Geo, Industry Verticals, Named Accounts, Federal/State/Local/Defense) Customer / Market Segment; Business Unit / Channel Country Codes (e.g., ISO 3166, UN) Role Codes Market Segments Country Codes / Currency Codes / Financial Accounts Date/Time, Time Zones (e.g., ISO 8601) Domain Values Universal Standard Products and Services Classification (UNSPSC), eCl@ss International Classification of Diseases (ICD) e.g., ICD9 à IC10 mappings Tax Rates Why manage reference data? Reference data carries contextual value and meaning and therefore its use can drive business logic that helps execute a business process, create a desired application behavior or provide meaningful segmentation to analyze transaction data. Further, mapping reference data often requires human judgment. Sample Use Cases of Reference Data Management Healthcare: Diagnostic Codes The reference data challenges in the healthcare industry offer a case in point. Part of being HIPAA compliant requires medical practitioners to transition diagnosis codes from ICD-9 to ICD-10, a medical coding scheme used to classify diseases, signs and symptoms, causes, etc. The transition to ICD-10 has a significant impact on business processes, procedures, contracts, and IT systems. Since both code sets ICD-9 and ICD-10 offer diagnosis codes of very different levels of granularity, human judgment is required to map ICD-9 codes to ICD-10. The process requires collaboration and consensus building among stakeholders much in the same way as does master data management. Moreover, to build reports to understand utilization, frequency and quality of diagnoses, medical practitioners may need to “cross-walk” mappings -- either forward to ICD-10 or backwards to ICD-9 depending upon the reporting time horizon. Spend Management: Product, Service & Supplier Codes Similarly, as an enterprise looks to rationalize suppliers and leverage their spend, conforming supplier codes, as well as product and service codes requires supporting multiple classification schemes that may include industry standards (e.g., UNSPSC, eCl@ss) or enterprise taxonomies. Aberdeen Group estimates that 90% of companies rely on spreadsheets and manual reviews to aggregate, classify and analyze spend data, and that data management activities account for 12-15% of the sourcing cycle and consume 30-50% of a commodity manager’s time. Creating a common map across the extended enterprise to rationalize codes across procurement, accounts payable, general ledger, credit card, procurement card (P-card) as well as ACH and bank systems can cut sourcing costs, improve compliance, lower inventory stock, and free up talent to focus on value added tasks. Change Management: Point of Sales Transaction Codes and Product Codes In the specialty finance industry, enterprises are confronted with usury laws – governed at the state and local level – that regulate financial product innovation as it relates to consumer loans, check cashing and pawn lending. To comply, it is important to demonstrate that transactions booked at the point of sale are posted against valid product codes that were on offer at the time of booking the sale. Since new products are being released at a steady stream, it is important to ensure timely and accurate mapping of point-of-sale transaction codes with the appropriate product and GL codes to comply with the changing regulations. Multi-National Companies: Industry Classification Schemes As companies grow and expand across geographies, a typical challenge they encounter with reference data represents reconciling various versions of industry classification schemes in use across nations. While the United States, Mexico and Canada conform to the North American Industry Classification System (NAICS) standard, European Union countries choose different variants of the NACE industry classification scheme. Multi-national companies must manage the individual national NACE schemes and reconcile the differences across countries. Enterprises must invest in a reference data change management application to address the challenge of distributing reference data changes to downstream applications and assess which applications were impacted by a given change. References 1 Master Data versus Reference Data, Malcolm Chisholm, April 1, 2006.

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• What are some good questions (and good/bad answers) to ask at an interview to gauge the competency of the company/team?

  - by Wayne M

  I'm already familiar with the Joel Test, but it's been my experience that some of the questions there have the answers "massaged" to make the company seem better than it is. I've had several jobs in the past that, for instance, claimed they had a QA process and did unit testing, and what they really meant is "The programmers test the app, and test with the debugger and via trial-and-error."; they said they used SVN but they just lumped everything into one giant repository and had no concept of branching/merging or anything more complicated than updating and committing; said they can build in one step and what they really mean is it's "one step" to copy dozens of files by hand from the programmer's PC to the live server. How do you go about properly gauging a company's environment to make sure that it's a well-evolved company and not stuck on doing things a certain way because they've done it for years and they're ignorant of change? You can almost never ask to see their source code, so you're stuck trying to figure out if the interviewer's answer is accurate or BS to make the company seem good. Besides the Joel Test what are some other good questions to get the proper feel for a company, and more importantly what are some good and bad answers that could indicate a good or bad company? I mean something like (take at face value, please, it's all I could think of at short notice): Question: How does the software team apply the SOLID principles and Inversion of Control to their code? Good Answer: We adhere to SOLID wherever possible; we use TDD so it kind of forces us to write abstract, testable code. We use Ninject for our IoC container because it's fairly easy to configure - it was that or StructureMap but I find Ninject a bit more intuitive, and who doesn't like ninjas? You're not a pirate, are you? Bad Answer: Our code is pretty secure, yeah. And what's this Inversion of Control thing? I've never heard of it before. You see what I did there. The "good" answer uses facts to back it up and has a bit of "in crowd" humor; the bad answer shows complete ignorance of the question - not necessarily a bad thing if you are interviewing for a manger/director position, but a terrible answer and a huge red flag if you're interviewing as a developer and talking to a senior developer or manager! My biggest problem at the moment is being able to take a generic response and gauge whether it's the good or bad answer; more often than not it's the bad kind and I find myself frustrated almost from day one at the new job. I suppose I could name drop if I ask about specific things (e.g. "Do you write unit tests?" and if the answer is yes, ask if they use NUnit, MbUnit or something else; if they mention data access ask if they use a clean ORM like NHibernate or something more coupled like EF or Linq) but is there another way short of being resolute to actually call the interview on things (which will almost certainly result in not getting the job, but if they are skirting the question it's probably not a job I want).

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• Unable to fix broken packages with sudo apt-get install -f

  - by Bob

  Here's my result, of sudo apt-get install -f. i have Ran it twice and got negative result. I believe there is an error at "error in Version string '0:3.6.1-dates for language English Translation data updates for all supported packages for: English" This same statement "error in Version string, caused me three days of attempting to download version 12.04. There is a bug report concerning the quoted text as well. Is there anyway to download the version without the language packs, why would I corrupt version 11.10? Also, when attempting to download Synaptic using sudo apt-get install synaptic, I get the same error message. Again I point out the initial download problems and the same error message receipt. Thanks b0b@b0b-IC780M-A:~$ sudo apt-get install -f [sudo] password for b0b: Reading package lists... Done Building dependency tree Reading state information... Done 0 upgraded, 0 newly installed, 0 to remove and 298 not upgraded. b0b@b0b-IC780M-A:~$ sudo apt-get install -f Reading package lists... Done Building dependency tree Reading state information... Done 0 upgraded, 0 newly installed, 0 to remove and 298 not upgraded. b0b@b0b-IC780M-A:~$ sudo apt-get upgrade install Reading package lists... Done Building dependency tree Reading state information... Done The following packages have been kept back: linux-headers-generic software-center The following packages will be upgraded: accountsservice acpi-support acpid aisleriot alsa-utils app-install-data-partner appmenu-qt apport apport-gtk apt-transport-https apt-utils aptdaemon aptdaemon-data apturl apturl-common banshee banshee-extension-soundmenu banshee-extension-ubuntuonemusicstore baobab bind9-host binutils bluez-alsa bluez-cups bluez-gstreamer brasero brasero-cdrkit brasero-common checkbox checkbox-gtk command-not-found command-not-found-data compiz compiz-core compiz-gnome compiz-plugins-default compiz-plugins-main-default cups cups-bsd cups-client cups-common cups-ppdc deja-dup desktop-file-utils dnsutils empathy empathy-common eog evince evince-common evolution-data-server evolution-data-server-common file-roller firefox firefox-globalmenu firefox-gnome-support gbrainy gcalctool gconf2 gconf2-common gedit gedit-common ghostscript ghostscript-cups ghostscript-x gir1.2-atspi-2.0 gir1.2-gconf-2.0 gir1.2-gnomebluetooth-1.0 gir1.2-gtk-3.0 gir1.2-gtksource-3.0 gir1.2-totem-1.0 gir1.2-unity-4.0 gir1.2-webkit-3.0 gnome-accessibility-themes gnome-bluetooth gnome-control-center gnome-control-center-data gnome-desktop3-data gnome-font-viewer gnome-games-common gnome-icon-theme gnome-mahjongg gnome-online-accounts gnome-orca gnome-power-manager gnome-screenshot gnome-search-tool gnome-session gnome-session-bin gnome-session-canberra gnome-session-common gnome-settings-daemon gnome-sudoku gnome-system-log gnome-system-monitor gnome-utils-common gnomine gstreamer0.10-gconf gstreamer0.10-plugins-good gstreamer0.10-pulseaudio gvfs gvfs-backends gvfs-bin gvfs-fuse gwibber gwibber-service gwibber-service-facebook gwibber-service-identica gwibber-service-twitter hpijs hplip hplip-cups hplip-data indicator-datetime indicator-session indicator-sound isc-dhcp-client isc-dhcp-common jockey-common jockey-gtk language-selector-common language-selector-gnome libaccountsservice0 libapt-inst1.3 libarchive1 libasound2-plugins libatk-adaptor libbind9-60 libbrasero-media3-1 libcamel-1.2-29 libcanberra-gtk-module libcanberra-gtk0 libcanberra-gtk3-0 libcanberra-gtk3-module libcanberra-pulse libcanberra0 libdecoration0 libdns69 libebackend-1.2-1 libebook1.2-12 libecal1.2-10 libedata-book-1.2-11 libedata-cal-1.2-13 libedataserver1.2-15 libedataserverui-3.0-1 libevince3-3 libgconf2-4 libgnome-bluetooth8 libgnome-control-center1 libgnome-desktop-3-2 libgoa-1.0-0 libgrip0 libgs9 libgs9-common libgtk-3-bin libgtksourceview-3.0-0 libgtksourceview-3.0-common libgweather-3-0 libgweather-common libgwibber-gtk2 libgwibber2 libhpmud0 libimobiledevice2 libisc62 libisccc60 libisccfg62 libjasper1 liblightdm-gobject-1-0 liblwres60 libmetacity-private0 libmission-control-plugins0 libmono-zeroconf1.0-cil libnautilus-extension1 libnm-glib-vpn1 libnm-glib4 libnm-util2 libnotify0.4-cil libnux-1.0-0 libnux-1.0-common libpam-gnome-keyring libreoffice-emailmerge libreoffice-style-human libsane-hpaio libsmbclient libsnmp-base libsnmp15 libsyncdaemon-1.0-1 libt1-5 libtotem0 libubuntuone-1.0-1 libubuntuone1.0-cil libunity-2d-private0 libunity-core-4.0-4 libunity6 libusbmuxd1 libwbclient0 libwebkitgtk-1.0-0 libwebkitgtk-1.0-common libwebkitgtk-3.0-0 libwebkitgtk-3.0-common libxml2 linux-generic linux-image-generic metacity metacity-common mobile-broadband-provider-info modemmanager mousetweaks multiarch-support nautilus nautilus-data nautilus-sendto-empathy network-manager nux-tools onboard openssl pulseaudio pulseaudio-esound-compat pulseaudio-module-bluetooth pulseaudio-module-gconf pulseaudio-module-x11 pulseaudio-utils python-apport python-aptdaemon python-aptdaemon-gtk python-aptdaemon.gtk3widgets python-aptdaemon.gtkwidgets python-brlapi python-cups python-cupshelpers python-gobject-cairo python-httplib2 python-launchpadlib python-libxml2 python-pam python-papyon python-pkg-resources python-problem-report python-pyatspi2 python-software-properties python-ubuntuone-client python-ubuntuone-storageprotocol samba-common samba-common-bin seahorse shotwell simple-scan smbclient sni-qt software-properties-common software-properties-gtk sudo system-config-printer-common system-config-printer-gnome system-config-printer-udev telepathy-indicator telepathy-mission-control-5 thunderbird thunderbird-globalmenu thunderbird-gnome-support tomboy totem totem-common totem-mozilla totem-plugins ttf-opensymbol ubuntu-desktop ubuntu-minimal ubuntu-standard ubuntuone-client ubuntuone-client-gnome ubuntuone-couch unity unity-2d unity-2d-launcher unity-2d-panel unity-2d-places unity-2d-spread unity-common unity-lens-applications unity-services update-manager update-manager-core update-notifier update-notifier-common usbmuxd vim-common vim-tiny vinagre vino xorg xserver-xorg xserver-xorg-input-all xserver-xorg-video-all xserver-xorg-video-intel xserver-xorg-video-openchrome xul-ext-ubufox 296 upgraded, 0 newly installed, 0 to remove and 2 not upgraded. Need to get 0 B/159 MB of archives. After this operation, 10.1 MB of additional disk space will be used. Do you want to continue [Y/n]? y Extracting templates from packages: 100% Preconfiguring packages ... dpkg: error: parsing file '/var/lib/dpkg/available' near line 4131 package 'python-zope.interface': error in Version string '0:3.6.1-dates for language English Translation data updates for all supported packages for: English . language-pack-en-base provides the bulk of translation data and is updated only seldom. This package provides frequent translation updates.': version string has embedded spaces E: Sub-process /usr/bin/dpkg returned an error code (2) b0b@b0b-IC780M-A:~$

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• Internet Explorer and margins

  - by Hailwood

  Hi there. I have some pretty simple html which is meant to make a layout as below. To push the tabs down from the userbar I am using margin-top: 35px; However in internet explorer the tabs are completly misaligned(the top of the tabs is where the bottom should be). So I need to use margin-top: -50px; for internet explorer. Why is this and how can I fix it without using a ie specific stylesheet <div id="pageHead"> <div id="userBar"> <span class="bold">Hi Matthew Hailwood | <a href="#">Logout</a> </div> <a href="http://localhost/buzz/" id="pageLogo"></a> <div id="pageTabs" class="clearfix"> <ul> <li><a href="http://localhost/buzzil/templates">Templates</a></li> <li><a href="http://localhost/buzzil/messaging">Messaging</a></li> <li><a href="http://localhost/buzzil/contacts">Contacts</a></li> </ul> </div> </div> With the css being #pageHead { height: 100px; } #pageLogo { float: left; width: 149px; height: 77px; margin-top: 11px; background: transparent url('../images/logo.png') no-repeat; } #userBar { text-align: right; color: #fff; margin-top: 10px; } #userBar a:link, #userBar a:visited, #userBar a:active { font-weight: normal; color: #E0B343; text-decoration: none; } .clearfix:after { content: "."; display: block; clear: both; visibility: hidden; line-height: 0; height: 0; } .clearfix { display: inline-block; } html[xmlns] .clearfix { display: block; } * html .clearfix { height: 1%; } #pageTabs { float: right; margin-top: 35px; } #pageTabs ul { position: relative; width: 100%; list-style: none; margin: 0; padding: 0; border-left: 1px solid #000; } #pageTabs ul li { float: right; background: url(../images/tabsBg.png) no-repeat 0% 0%; border-left: 1px solid #000; margin-left: -1px; } #pageTabs ul li a:link, #pageTabs ul li a:visited, #pageTabs ul li a:active { color: #fff; background: url(../images/tabsBg.png) no-repeat 100% 0%; display: block; font-size: 14px; font-weight: bold; line-height: 42px; text-transform: uppercase; padding: 4px 32px; text-decoration: none; } #pageTabs ul li a:hover, #pageTabs ul li a:focus { text-decoration: underline; }

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• Tessellation Texture Coordinates

  - by Stuart Martin

  Firstly some info - I'm using DirectX 11 , C++ and I'm a fairly good programmer but new to tessellation and not a master graphics programmer. I'm currently implementing a tessellation system for a terrain model, but i have reached a snag. My current system produces a terrain model from a height map complete with multiple texture coordinates, normals, binormals and tangents for rendering. Now when i was using a simple vertex and pixel shader combination everything worked perfectly but since moving to include a hull and domain shader I'm slightly confused and getting strange results. My terrain is a high detail model but the textured results are very large patches of solid colour. My current setup passes the model data into the vertex shader then through the hull into the domain and then finally into the pixel shader for use in rendering. My only thought is that in my hull shader i pass the information into the domain shader per patch and this is producing the large areas of solid colour because each patch has identical information. Lighting and normal data are also slightly off but not as visibly as texturing. Below is a copy of my hull shader that does not work correctly because i think the way that i am passing the data through is incorrect. If anyone can help me out but suggesting an alternative way to get the required data into the pixel shader? or by showing me the correct way to handle the data in the hull shader id be very thankful! cbuffer TessellationBuffer { float tessellationAmount; float3 padding; }; struct HullInputType { float3 position : POSITION; float2 tex : TEXCOORD0; float3 normal : NORMAL; float3 tangent : TANGENT; float3 binormal : BINORMAL; float2 tex2 : TEXCOORD1; }; struct ConstantOutputType { float edges[3] : SV_TessFactor; float inside : SV_InsideTessFactor; }; struct HullOutputType { float3 position : POSITION; float2 tex : TEXCOORD0; float3 normal : NORMAL; float3 tangent : TANGENT; float3 binormal : BINORMAL; float2 tex2 : TEXCOORD1; float4 depthPosition : TEXCOORD2; }; ConstantOutputType ColorPatchConstantFunction(InputPatch<HullInputType, 3> inputPatch, uint patchId : SV_PrimitiveID) { ConstantOutputType output; output.edges[0] = tessellationAmount; output.edges[1] = tessellationAmount; output.edges[2] = tessellationAmount; output.inside = tessellationAmount; return output; } [domain("tri")] [partitioning("integer")] [outputtopology("triangle_cw")] [outputcontrolpoints(3)] [patchconstantfunc("ColorPatchConstantFunction")] HullOutputType ColorHullShader(InputPatch<HullInputType, 3> patch, uint pointId : SV_OutputControlPointID, uint patchId : SV_PrimitiveID) { HullOutputType output; output.position = patch[pointId].position; output.tex = patch[pointId].tex; output.tex2 = patch[pointId].tex2; output.normal = patch[pointId].normal; output.tangent = patch[pointId].tangent; output.binormal = patch[pointId].binormal; return output; } Edited to include the domain shader:- [domain("tri")] PixelInputType ColorDomainShader(ConstantOutputType input, float3 uvwCoord : SV_DomainLocation, const OutputPatch<HullOutputType, 3> patch) { float3 vertexPosition; PixelInputType output; // Determine the position of the new vertex. vertexPosition = uvwCoord.x * patch[0].position + uvwCoord.y * patch[1].position + uvwCoord.z * patch[2].position; output.position = mul(float4(vertexPosition, 1.0f), worldMatrix); output.position = mul(output.position, viewMatrix); output.position = mul(output.position, projectionMatrix); output.depthPosition = output.position; output.tex = patch[0].tex; output.tex2 = patch[0].tex2; output.normal = patch[0].normal; output.tangent = patch[0].tangent; output.binormal = patch[0].binormal; return output; }

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• Diving into OpenStack Network Architecture - Part 2 - Basic Use Cases

  - by Ronen Kofman

    rkofman Normal rkofman 4 138 2014-06-05T03:38:00Z 2014-06-05T05:04:00Z 3 2735 15596 Oracle Corporation 129 36 18295 12.00 Clean Clean false false false false EN-US X-NONE HE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:Arial; mso-bidi-theme-font:minor-bidi; mso-bidi-language:AR-SA;} In the previous post we reviewed several network components including Open vSwitch, Network Namespaces, Linux Bridges and veth pairs. In this post we will take three simple use cases and see how those basic components come together to create a complete SDN solution in OpenStack. With those three use cases we will review almost the entire network setup and see how all the pieces work together. The use cases we will use are: 1.       Create network – what happens when we create network and how can we create multiple isolated networks 2.       Launch a VM – once we have networks we can launch VMs and connect them to networks. 3.       DHCP request from a VM – OpenStack can automatically assign IP addresses to VMs. This is done through local DHCP service controlled by OpenStack Neutron. We will see how this service runs and how does a DHCP request and response look like. In this post we will show connectivity, we will see how packets get from point A to point B. We first focus on how a configured deployment looks like and only later we will discuss how and when the configuration is created. Personally I found it very valuable to see the actual interfaces and how they connect to each other through examples and hands on experiments. After the end game is clear and we know how the connectivity works, in a later post, we will take a step back and explain how Neutron configures the components to be able to provide such connectivity.  We are going to get pretty technical shortly and I recommend trying these examples on your own deployment or using the Oracle OpenStack Tech Preview. Understanding these three use cases thoroughly and how to look at them will be very helpful when trying to debug a deployment in case something does not work. Use case #1: Create Network Create network is a simple operation it can be performed from the GUI or command line. When we create a network in OpenStack the network is only available to the tenant who created it or it could be defined as “shared” and then it can be used by all tenants. A network can have multiple subnets but for this demonstration purpose and for simplicity we will assume that each network has exactly one subnet. Creating a network from the command line will look like this: # neutron net-create net1 Created a new network: +---------------------------+--------------------------------------+ | Field                     | Value                                | +---------------------------+--------------------------------------+ | admin_state_up            | True                                 | | id                        | 5f833617-6179-4797-b7c0-7d420d84040c | | name                      | net1                                 | | provider:network_type     | vlan                                 | | provider:physical_network | default                              | | provider:segmentation_id  | 1000                                 | | shared                    | False                                | | status                    | ACTIVE                               | | subnets                   |                                      | | tenant_id                 | 9796e5145ee546508939cd49ad59d51f     | +---------------------------+--------------------------------------+ Creating a subnet for this network will look like this: # neutron subnet-create net1 10.10.10.0/24 Created a new subnet: +------------------+------------------------------------------------+ | Field            | Value                                          | +------------------+------------------------------------------------+ | allocation_pools | {"start": "10.10.10.2", "end": "10.10.10.254"} | | cidr             | 10.10.10.0/24                                  | | dns_nameservers  |                                                | | enable_dhcp      | True                                           | | gateway_ip       | 10.10.10.1                                     | | host_routes      |                                                | | id               | 2d7a0a58-0674-439a-ad23-d6471aaae9bc           | | ip_version       | 4                                              | | name             |                                                | | network_id       | 5f833617-6179-4797-b7c0-7d420d84040c           | | tenant_id        | 9796e5145ee546508939cd49ad59d51f               | +------------------+------------------------------------------------+ We now have a network and a subnet, on the network topology view this looks like this: Now let’s dive in and see what happened under the hood. Looking at the control node we will discover that a new namespace was created: # ip netns list qdhcp-5f833617-6179-4797-b7c0-7d420d84040c   The name of the namespace is qdhcp-<network id> (see above), let’s look into the namespace and see what’s in it: # ip netns exec qdhcp-5f833617-6179-4797-b7c0-7d420d84040c ip addr 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN     link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00     inet 127.0.0.1/8 scope host lo     inet6 ::1/128 scope host        valid_lft forever preferred_lft forever 12: tap26c9b807-7c: <BROADCAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN     link/ether fa:16:3e:1d:5c:81 brd ff:ff:ff:ff:ff:ff     inet 10.10.10.3/24 brd 10.10.10.255 scope global tap26c9b807-7c     inet6 fe80::f816:3eff:fe1d:5c81/64 scope link        valid_lft forever preferred_lft forever   We see two interfaces in the namespace, one is the loopback and the other one is an interface called “tap26c9b807-7c”. This interface has the IP address of 10.10.10.3 and it will also serve dhcp requests in a way we will see later. Let’s trace the connectivity of the “tap26c9b807-7c” interface from the namespace.  First stop is OVS, we see that the interface connects to bridge  “br-int” on OVS: # ovs-vsctl show 8a069c7c-ea05-4375-93e2-b9fc9e4b3ca1     Bridge "br-eth2"         Port "br-eth2"             Interface "br-eth2"                 type: internal         Port "eth2"             Interface "eth2"         Port "phy-br-eth2"             Interface "phy-br-eth2"     Bridge br-ex         Port br-ex             Interface br-ex                 type: internal     Bridge br-int         Port "int-br-eth2"             Interface "int-br-eth2"         Port "tap26c9b807-7c"             tag: 1             Interface "tap26c9b807-7c"                 type: internal         Port br-int             Interface br-int                 type: internal     ovs_version: "1.11.0"   In the picture above we have a veth pair which has two ends called “int-br-eth2” and "phy-br-eth2", this veth pair is used to connect two bridge in OVS "br-eth2" and "br-int". In the previous post we explained how to check the veth connectivity using the ethtool command. It shows that the two are indeed a pair: # ethtool -S int-br-eth2 NIC statistics:      peer_ifindex: 10 . .   #ip link . . 10: phy-br-eth2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000 . . Note that “phy-br-eth2” is connected to a bridge called "br-eth2" and one of this bridge's interfaces is the physical link eth2. This means that the network which we have just created has created a namespace which is connected to the physical interface eth2. eth2 is the “VM network” the physical interface where all the virtual machines connect to where all the VMs are connected. About network isolation: OpenStack supports creation of multiple isolated networks and can use several mechanisms to isolate the networks from one another. The isolation mechanism can be VLANs, VxLANs or GRE tunnels, this is configured as part of the initial setup in our deployment we use VLANs. When using VLAN tagging as an isolation mechanism a VLAN tag is allocated by Neutron from a pre-defined VLAN tags pool and assigned to the newly created network. By provisioning VLAN tags to the networks Neutron allows creation of multiple isolated networks on the same physical link.  The big difference between this and other platforms is that the user does not have to deal with allocating and managing VLANs to networks. The VLAN allocation and provisioning is handled by Neutron which keeps track of the VLAN tags, and responsible for allocating and reclaiming VLAN tags. In the example above net1 has the VLAN tag 1000, this means that whenever a VM is created and connected to this network the packets from that VM will have to be tagged with VLAN tag 1000 to go on this particular network. This is true for namespace as well, if we would like to connect a namespace to a particular network we have to make sure that the packets to and from the namespace are correctly tagged when they reach the VM network. In the example above we see that the namespace interface “tap26c9b807-7c” has vlan tag 1 assigned to it, if we examine OVS we see that it has flows which modify VLAN tag 1 to VLAN tag 1000 when a packet goes to the VM network on eth2 and vice versa. We can see this using the dump-flows command on OVS for packets going to the VM network we see the modification done on br-eth2: #  ovs-ofctl dump-flows br-eth2 NXST_FLOW reply (xid=0x4):  cookie=0x0, duration=18669.401s, table=0, n_packets=857, n_bytes=163350, idle_age=25, priority=4,in_port=2,dl_vlan=1 actions=mod_vlan_vid:1000,NORMAL  cookie=0x0, duration=165108.226s, table=0, n_packets=14, n_bytes=1000, idle_age=5343, hard_age=65534, priority=2,in_port=2 actions=drop  cookie=0x0, duration=165109.813s, table=0, n_packets=1671, n_bytes=213304, idle_age=25, hard_age=65534, priority=1 actions=NORMAL   For packets coming from the interface to the namespace we see the following modification: #  ovs-ofctl dump-flows br-int NXST_FLOW reply (xid=0x4):  cookie=0x0, duration=18690.876s, table=0, n_packets=1610, n_bytes=210752, idle_age=1, priority=3,in_port=1,dl_vlan=1000 actions=mod_vlan_vid:1,NORMAL  cookie=0x0, duration=165130.01s, table=0, n_packets=75, n_bytes=3686, idle_age=4212, hard_age=65534, priority=2,in_port=1 actions=drop  cookie=0x0, duration=165131.96s, table=0, n_packets=863, n_bytes=160727, idle_age=1, hard_age=65534, priority=1 actions=NORMAL   To summarize we can see that when a user creates a network Neutron creates a namespace and this namespace is connected through OVS to the “VM network”. OVS also takes care of tagging the packets from the namespace to the VM network with the correct VLAN tag and knows to modify the VLAN for packets coming from VM network to the namespace. Now let’s see what happens when a VM is launched and how it is connected to the “VM network”. Use case #2: Launch a VM Launching a VM can be done from Horizon or from the command line this is how we do it from Horizon: Attach the network: And Launch Once the virtual machine is up and running we can see the associated IP using the nova list command : # nova list +--------------------------------------+--------------+--------+------------+-------------+-----------------+ | ID                                   | Name         | Status | Task State | Power State | Networks        | +--------------------------------------+--------------+--------+------------+-------------+-----------------+ | 3707ac87-4f5d-4349-b7ed-3a673f55e5e1 | Oracle Linux | ACTIVE | None       | Running     | net1=10.10.10.2 | +--------------------------------------+--------------+--------+------------+-------------+-----------------+ The nova list command shows us that the VM is running and that the IP 10.10.10.2 is assigned to this VM. Let’s trace the connectivity from the VM to VM network on eth2 starting with the VM definition file. The configuration files of the VM including the virtual disk(s), in case of ephemeral storage, are stored on the compute node at/var/lib/nova/instances/<instance-id>/. Looking into the VM definition file ,libvirt.xml,  we see that the VM is connected to an interface called “tap53903a95-82” which is connected to a Linux bridge called “qbr53903a95-82”: <interface type="bridge">       <mac address="fa:16:3e:fe:c7:87"/>       <source bridge="qbr53903a95-82"/>       <target dev="tap53903a95-82"/>     </interface>   Looking at the bridge using the brctl show command we see this: # brctl show bridge name     bridge id               STP enabled     interfaces qbr53903a95-82          8000.7e7f3282b836       no              qvb53903a95-82                                                         tap53903a95-82    The bridge has two interfaces, one connected to the VM (“tap53903a95-82 “) and another one ( “qvb53903a95-82”) connected to “br-int” bridge on OVS: # ovs-vsctl show 83c42f80-77e9-46c8-8560-7697d76de51c     Bridge "br-eth2"         Port "br-eth2"             Interface "br-eth2"                 type: internal         Port "eth2"             Interface "eth2"         Port "phy-br-eth2"             Interface "phy-br-eth2"     Bridge br-int         Port br-int             Interface br-int                 type: internal         Port "int-br-eth2"             Interface "int-br-eth2"         Port "qvo53903a95-82"             tag: 3             Interface "qvo53903a95-82"     ovs_version: "1.11.0"   As we showed earlier “br-int” is connected to “br-eth2” on OVS using the veth pair int-br-eth2,phy-br-eth2 and br-eth2 is connected to the physical interface eth2. The whole flow end to end looks like this: VM è tap53903a95-82 (virtual interface)è qbr53903a95-82 (Linux bridge) è qvb53903a95-82 (interface connected from Linux bridge to OVS bridge br-int) è int-br-eth2 (veth one end) è phy-br-eth2 (veth the other end) è eth2 physical interface. The purpose of the Linux Bridge connecting to the VM is to allow security group enforcement with iptables. Security groups are enforced at the edge point which are the interface of the VM, since iptables nnot be applied to OVS bridges we use Linux bridge to apply them. In the future we hope to see this Linux Bridge going away rules.  VLAN tags: As we discussed in the first use case net1 is using VLAN tag 1000, looking at OVS above we see that qvo41f1ebcf-7c is tagged with VLAN tag 3. The modification from VLAN tag 3 to 1000 as we go to the physical network is done by OVS  as part of the packet flow of br-eth2 in the same way we showed before. To summarize, when a VM is launched it is connected to the VM network through a chain of elements as described here. During the packet from VM to the network and back the VLAN tag is modified. Use case #3: Serving a DHCP request coming from the virtual machine In the previous use cases we have shown that both the namespace called dhcp-<some id> and the VM end up connecting to the physical interface eth2  on their respective nodes, both will tag their packets with VLAN tag 1000.We saw that the namespace has an interface with IP of 10.10.10.3. Since the VM and the namespace are connected to each other and have interfaces on the same subnet they can ping each other, in this picture we see a ping from the VM which was assigned 10.10.10.2 to the namespace: The fact that they are connected and can ping each other can become very handy when something doesn’t work right and we need to isolate the problem. In such case knowing that we should be able to ping from the VM to the namespace and back can be used to trace the disconnect using tcpdump or other monitoring tools. To serve DHCP requests coming from VMs on the network Neutron uses a Linux tool called “dnsmasq”,this is a lightweight DNS and DHCP service you can read more about it here. If we look at the dnsmasq on the control node with the ps command we see this: dnsmasq --no-hosts --no-resolv --strict-order --bind-interfaces --interface=tap26c9b807-7c --except-interface=lo --pid-file=/var/lib/neutron/dhcp/5f833617-6179-4797-b7c0-7d420d84040c/pid --dhcp-hostsfile=/var/lib/neutron/dhcp/5f833617-6179-4797-b7c0-7d420d84040c/host --dhcp-optsfile=/var/lib/neutron/dhcp/5f833617-6179-4797-b7c0-7d420d84040c/opts --leasefile-ro --dhcp-range=tag0,10.10.10.0,static,120s --dhcp-lease-max=256 --conf-file= --domain=openstacklocal The service connects to the tap interface in the namespace (“--interface=tap26c9b807-7c”), If we look at the hosts file we see this: # cat  /var/lib/neutron/dhcp/5f833617-6179-4797-b7c0-7d420d84040c/host fa:16:3e:fe:c7:87,host-10-10-10-2.openstacklocal,10.10.10.2   If you look at the console output above you can see the MAC address fa:16:3e:fe:c7:87 which is the VM MAC. This MAC address is mapped to IP 10.10.10.2 and so when a DHCP request comes with this MAC dnsmasq will return the 10.10.10.2.If we look into the namespace at the time we initiate a DHCP request from the VM (this can be done by simply restarting the network service in the VM) we see the following: # ip netns exec qdhcp-5f833617-6179-4797-b7c0-7d420d84040c tcpdump -n 19:27:12.191280 IP 0.0.0.0.bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request from fa:16:3e:fe:c7:87, length 310 19:27:12.191666 IP 10.10.10.3.bootps > 10.10.10.2.bootpc: BOOTP/DHCP, Reply, length 325   To summarize, the DHCP service is handled by dnsmasq which is configured by Neutron to listen to the interface in the DHCP namespace. Neutron also configures dnsmasq with the combination of MAC and IP so when a DHCP request comes along it will receive the assigned IP. Summary In this post we relied on the components described in the previous post and saw how network connectivity is achieved using three simple use cases. These use cases gave a good view of the entire network stack and helped understand how an end to end connection is being made between a VM on a compute node and the DHCP namespace on the control node. One conclusion we can draw from what we saw here is that if we launch a VM and it is able to perform a DHCP request and receive a correct IP then there is reason to believe that the network is working as expected. We saw that a packet has to travel through a long list of components before reaching its destination and if it has done so successfully this means that many components are functioning properly. In the next post we will look at some more sophisticated services Neutron supports and see how they work. We will see that while there are some more components involved for the most part the concepts are the same. @RonenKofman

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• Ask HTG: How Can I Check the Age of My Windows Installation?

  - by Jason Fitzpatrick

  Curious about when you installed Windows and how long you’ve been chugging along without a system refresh? Read on as we show you a simple way to see how long-in-the-tooth your Windows installation is. Dear How-To Geek, It feels like it has been forever since I installed Windows 7 and I’m starting to wonder if some of the performance issues I’m experiencing have something to do with how long ago it was installed. It isn’t crashing or anything horrible, mind you, it just feels slower than it used to and I’m wondering if I should reinstall it to wipe the slate clean. Is there a simple way to determine the original installation date of Windows on its host machine? Sincerely, Worried in Windows Although you only intended to ask one question, you actually asked two. Your direct question is an easy one to answer (how to check the Windows installation date). The indirect question is, however, a little trickier (if you need to reinstall Windows to get a performance boost). Let’s start off with the easy one: how to check your installation date. Windows includes a handy little application just for the purposes of pulling up system information like the installation date, among other things. Open the Start Menu and type cmd in the run box (or, alternatively, press WinKey+R to pull up the run dialog and enter the same command). At the command prompt, type systeminfo.exe Give the application a moment to run; it takes around 15-20 seconds to gather all the data. You’ll most likely need to scroll back up in the console window to find the section at the top that lists operating system stats. What you care about is Original Install Date: We’ve been running the machine we tested the command on since August 23 2009. For the curious, that’s one month and a day after the initial public release of Windows 7 (after we were done playing with early test releases and spent a month mucking around in the guts of Windows 7 to report on features and flaws, we ran a new clean installation and kept on trucking). Now, you might be asking yourself: Why haven’t they reinstalled Windows in all that time? Haven’t things slowed down? Haven’t they upgraded hardware? The truth of the matter is, in most cases there’s no need to completely wipe your computer and start from scratch to resolve issues with Windows and, if you don’t bog your system down with unnecessary and poorly written software, things keep humming along. In fact, we even migrated this machine from a traditional mechanical hard drive to a newer solid-state drive back in 2011. Even though we’ve tested piles of software since then, the machine is still rather clean because 99% of that testing happened in a virtual machine. That’s not just a trick for technology bloggers, either, virtualizing is a handy trick for anyone who wants to run a rock solid base OS and avoid the bog-down-and-then-refresh cycle that can plague a heavily used machine. So while it might be the case that you’ve been running Windows 7 for years and heavy software installation and use has bogged your system down to the point a refresh is in order, we’d strongly suggest reading over the following How-To Geek guides to see if you can’t wrangle the machine into shape without a total wipe (and, if you can’t, at least you’ll be in a better position to keep the refreshed machine light and zippy): HTG Explains: Do You Really Need to Regularly Reinstall Windows? PC Cleaning Apps are a Scam: Here’s Why (and How to Speed Up Your PC) The Best Tips for Speeding Up Your Windows PC Beginner Geek: How to Reinstall Windows on Your Computer Everything You Need to Know About Refreshing and Resetting Your Windows 8 PC Armed with a little knowledge, you too can keep a computer humming along until the next iteration of Windows comes along (and beyond) without the hassle of reinstalling Windows and all your apps.         

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• The Power to Control Power

  - by speakjava

  I'm currently working on a number of projects using embedded Java on the Raspberry Pi and Beagle Board.  These are nice and small, so don't take up much room on my desk as you can see in this picture. As you can also see I have power and network connections emerging from under my desk.  One of the (admittedly very minor) drawbacks of these systems is that they have no on/off switch.  Instead you insert or remove the power connector (USB for the RasPi, a barrel connector for the Beagle).  For the Beagle Board this can potentially be an issue; with the micro-SD card located right next to the connector it has been known for people to eject the card when trying to power off the board, which can be quite serious for the hardware. The alternative is obviously to leave the boards plugged in and then disconnect the power from the outlet.  Simple enough, but a picture of underneath my desk shows that this is not the ideal situation either. This made me think that it would be great if I could have some way of controlling a mains voltage outlet using a remote switch or, even better, from software via a USB connector.  A search revealed not much that fit my requirements, and anything that was close seemed very expensive.  Obviously the only way to solve this was to build my own.Here's my solution.  I decided my system would support both control mechanisms (remote physical switch and USB computer control) and be modular in its design for optimum flexibility.  I did a bit of searching and found a company in Hong Kong that were offering solid state relays for 99p plus shipping (£2.99, but still made the total price very reasonable).  These would handle up to 380V AC on the output side so more than capable of coping with the UK 240V supply.  The other great thing was that being solid state, the input would work with a range of 3-32V and required a very low current of 7.5mA at 12V.  For the USB control an Arduino board seemed the obvious low-cost and simple choice.  Given the current requirments of the relay, the Arduino would not require the additional power supply and could be powered just from the USB.Having secured the relays I popped down to Homebase for a couple of 13A sockets, RS for a box and an Arduino and Maplin for a toggle switch.  The circuit is pretty straightforward, as shown in the diagram (only one output is shown to make it as simple as possible).  Originally I used a 2 pole toggle switch to select the remote switch or USB control by switching the negative connections of the low voltage side.  Unfortunately, the resistance between the digital pins of the Arduino board was not high enough, so when using one of the remote switches it would turn on both of the outlets.  I changed to a 4 pole switch and isolated both positive and negative connections. IMPORTANT NOTE: If you want to follow my design, please be aware that it requires working with mains voltages.  If you are at all concerned with your ability to do this please consult a qualified electrician to help you.It was a tight fit, especially getting the Arduino in, but in the end it all worked.  The completed box is shown in the photos. The remote switch was pretty simple just requiring the squeezing of two rocker switches and a 9V battery into the small RS supplied box.  I repurposed a standard stereo cable with phono plugs to connect the switch box to the mains outlets.  I chopped off one set of plugs and wired it to the rocker switches.  The photo shows the RasPi and the Beagle board now controllable from the switch box on the desk. I've tested the Arduino side of things and this works fine.  Next I need to write some software to provide an interface for control of the outlets.  I'm thinking a JavaFX GUI would be in keeping with the total overkill style of this project.

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• Something about Property Management or &hellip; the understanding of SharePoint Admins/roles ?!?

  - by Enrique Lima

  When I talk about SharePoint, for some reason it comes to my mind as if it were property management and all the tasks associated with it. So, imagine you have a lot ( a piece of land of sorts), you then decide there is something you want to do with it.  So, you make the choice of having a building built.  Now, in order to go forward with your plan, you need to check what the rules/regulations are.  Has is it been zoned residential, commercial, industrial … you get the idea.  This to me sounds like Governance.  The what am I to do given a defined set of rules. We keep on moving forward based on those rules.  And with this we start the process of building, the building process takes us to survey the land, identify what our boundaries are.  And as we go along we start getting the idea in our head as to what we will do as far as the building goes.  We identify the essentials of the building, basic services and such.  All in all, we plan.  And as with many things we do, we like solid foundations.  What a solid foundation looks like will depend on where and what we build.  The way buildings are built depends in many ways in being able to foresee the potential for natural disasters or to try to leverage the lay of the land.  Sound familiar?  We have done our Requirements Gathering. We have the building in place, we have followed the zoning rules, we have implemented services.  But we need someone to manage the building, now we move on to the human side of the story.  We want to establish a means to normalcy in the building, someone that can be the monitoring agent as to the “what’s going on?” of it.  This person will be tasked with making sure all basic services are functional, that measures are taken if there is an issue and so on.  Enter the Farm Administrator. In a way, we establish an extension of the rules to make sure the building and the apartments/offices build follow a standard set of rules too. Now, in turn you will have people leasing or buying the apartments/offices, they will be the keepers of that space.  So, now we are building sites, we have moved from having the building (farm) ready, to leasing/selling offices/apartments (site collections).  There will be someone assuming responsibility for those offices, that person will authorize or be informed about activities and also who not only gets a code into the building, but perhaps a key to the office.  Enter Site Collection Administrator.  And then perhaps we move on to the person that would be responsible for specifics within the office, for example a Human Resources Manager or Coordinator.  They will have specific control and knowledge about people.  A facilities coordinator, and so on.  I would translate that into Site Administrators. With that said then, we identify the following: Role Name Responsibility (but not limited to) Farm Administrator Infrastructure Site Collection Admin Policies for Content, Hierarchy, Recycle Bin, Security and Access Site Owner (Site Admin) Security and Access, Training, Guidance, Manage Templates All in all there are different levels of responsibility to be handled, but it is very important to understand what they are and what they mean. Here is a link to very well laid out explanation on this … http://www.endusersharepoint.com/2009/08/11/site-managers-and-end-user-expectations-roles-and-responsibilities/

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• Performance triage

  - by Dave

  Folks often ask me how to approach a suspected performance issue. My personal strategy is informed by the fact that I work on concurrency issues. (When you have a hammer everything looks like a nail, but I'll try to keep this general). A good starting point is to ask yourself if the observed performance matches your expectations. Expectations might be derived from known system performance limits, prototypes, and other software or environments that are comparable to your particular system-under-test. Some simple comparisons and microbenchmarks can be useful at this stage. It's also useful to write some very simple programs to validate some of the reported or expected system limits. Can that disk controller really tolerate and sustain 500 reads per second? To reduce the number of confounding factors it's better to try to answer that question with a very simple targeted program. And finally, nothing beats having familiarity with the technologies that underlying your particular layer. On the topic of confounding factors, as our technology stacks become deeper and less transparent, we often find our own technology working against us in some unexpected way to choke performance rather than simply running into some fundamental system limit. A good example is the warm-up time needed by just-in-time compilers in Java Virtual Machines. I won't delve too far into that particular hole except to say that it's rare to find good benchmarks and methodology for java code. Another example is power management on x86. Power management is great, but it can take a while for the CPUs to throttle up from low(er) frequencies to full throttle. And while I love "turbo" mode, it makes benchmarking applications with multiple threads a chore as you have to remember to turn it off and then back on otherwise short single-threaded runs may look abnormally fast compared to runs with higher thread counts. In general for performance characterization I disable turbo mode and fix the power governor at "performance" state. Another source of complexity is the scheduler, which I've discussed in prior blog entries. Lets say I have a running application and I want to better understand its behavior and performance. We'll presume it's warmed up, is under load, and is an execution mode representative of what we think the norm would be. It should be in steady-state, if a steady-state mode even exists. On Solaris the very first thing I'll do is take a set of "pstack" samples. Pstack briefly stops the process and walks each of the stacks, reporting symbolic information (if available) for each frame. For Java, pstack has been augmented to understand java frames, and even report inlining. A few pstack samples can provide powerful insight into what's actually going on inside the program. You'll be able to see calling patterns, which threads are blocked on what system calls or synchronization constructs, memory allocation, etc. If your code is CPU-bound then you'll get a good sense where the cycles are being spent. (I should caution that normal C/C++ inlining can diffuse an otherwise "hot" method into other methods. This is a rare instance where pstack sampling might not immediately point to the key problem). At this point you'll need to reconcile what you're seeing with pstack and your mental model of what you think the program should be doing. They're often rather different. And generally if there's a key performance issue, you'll spot it with a moderate number of samples. I'll also use OS-level observability tools to lock for the existence of bottlenecks where threads contend for locks; other situations where threads are blocked; and the distribution of threads over the system. On Solaris some good tools are mpstat and too a lesser degree, vmstat. Try running "mpstat -a 5" in one window while the application program runs concurrently. One key measure is the voluntary context switch rate "vctx" or "csw" which reflects threads descheduling themselves. It's also good to look at the user; system; and idle CPU percentages. This can give a broad but useful understanding if your threads are mostly parked or mostly running. For instance if your program makes heavy use of malloc/free, then it might be the case you're contending on the central malloc lock in the default allocator. In that case you'd see malloc calling lock in the stack traces, observe a high csw/vctx rate as threads block for the malloc lock, and your "usr" time would be less than expected. Solaris dtrace is a wonderful and invaluable performance tool as well, but in a sense you have to frame and articulate a meaningful and specific question to get a useful answer, so I tend not to use it for first-order screening of problems. It's also most effective for OS and software-level performance issues as opposed to HW-level issues. For that reason I recommend mpstat & pstack as my the 1st step in performance triage. If some other OS-level issue is evident then it's good to switch to dtrace to drill more deeply into the problem. Only after I've ruled out OS-level issues do I switch to using hardware performance counters to look for architectural impediments.

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• Access Master Page Controls II

  - by Bunch

  Here is another way to access master page controls. This way has a bit less coding then my previous post on the subject. The scenario would be that you have a master page with a few navigation buttons at the top for users to navigate the app. After a button is clicked the corresponding aspx page would load in the ContentPlaceHolder. To make it easier for the users to see what page they are on I wanted the clicked navigation button to change color. This would be a quick visual for the user and is useful when inevitably they are interrupted with something else and cannot get back to what they were doing for a little while. Anyway the code is something like this. Master page: <body>     <form id="form1" runat="server">     <div id="header">     <asp:Panel ID="Panel1" runat="server" CssClass="panelHeader" Width="100%">        <center>            <label style="font-size: large; color: White;">Test Application</label>        </center>       <asp:Button ID="btnPage1" runat="server" Text="Page1" PostBackUrl="~/Page1.aspx" CssClass="navButton"/>       <asp:Button ID="btnPage2" runat="server" Text="Page2" PostBackUrl="~/Page2.aspx" CssClass="navButton"/>       <br />     </asp:Panel>     <br />     </div>     <div>         <asp:scriptmanager ID="Scriptmanager1" runat="server"></asp:scriptmanager>         <asp:ContentPlaceHolder id="ContentPlaceHolder1" runat="server">         </asp:ContentPlaceHolder>     </div>     </form> </body> Page 1: VB Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load     Dim clickedButton As Button = Master.FindControl("btnPage1")     clickedButton.CssClass = "navButtonClicked" End Sub CSharp protected void Page_Load(object sender, EventArgs e) {     Button clickedButton;     clickedButton = (Button)Master.FindControl("btnPage1");     clickedButton.CssClass = "navButtonClicked"; } CSS: .navButton {     background-color: White;     border: 1px #4e667d solid;     color: #2275a7;     display: inline;     line-height: 1.35em;     text-decoration: none;     white-space: nowrap;     width: 100px;     text-align: center;     margin-bottom: 10px;     margin-left: 5px;     height: 30px; } .navButtonClicked {     background-color:#FFFF86;     border: 1px #4e667d solid;     color: #2275a7;     display: inline;     line-height: 1.35em;     text-decoration: none;     white-space: nowrap;     width: 100px;     text-align: center;     margin-bottom: 10px;     margin-left: 5px;     height: 30px; } The idea is pretty simple, use FindControl for the master page in the page load of your aspx page. In the example I changed the CssClass for the aspx page's corresponding button to navButtonClicked which has a different background-color and makes the clicked button stand out. Technorati Tags: ASP.Net,CSS,CSharp,VB.Net

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• Does Jquery and Mootools usually have conflict if both are used on a webpage? [migrated]

  - by Charming Prince

  I have this website am designing, i tried using mootools 1.31 to animate some of the div boxes when clicked or when the mouse hover rounds it, to shows the content. the thing is that it doesn't seem to work on the webpage, but if i try the same script on a blank webpage it works, am thinking probably it's because i have Jquery 1.52 on the same page and maybe both scripts are conflicting with each other because, if i remove the Jquery, the Mootools works. What should be my option, because i need the Jquery to do some validations for me, so i can't remove it completely. Here are the codes <script> //-vertical var mySlide = new Fx.Slide('test'); $('slidein').addEvent('click', function(e){ e = new Event(e); mySlide.slideIn(); e.stop(); }); $('slideout').addEvent('click', function(e){ e = new Event(e); mySlide.slideOut(); e.stop(); }); $('toggle').addEvent('click', function(e){ e = new Event(e); mySlide.toggle(); e.stop(); }); $('hide').addEvent('click', function(e){ e = new Event(e); mySlide.hide(); e.stop(); }); </script> here's the HTML <html> <h3 class="section">Fx.Slide Vertical</h3> <a id="slideout" href="#">slideout</a> | <a id="slidein" href="#">slidein</a> | <a id="toggle" href="#"> toggle</a> | <a id="hide" href="#">hide</a> <div id="test"> Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad mi nim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum. </div> Here's the CSS #test { background: #222; color: #fff; padding: 10px; margin: 20px; border: 10px solid pink; } #test2 { background: #222; color: #fff; padding: 10px; margin: 20px; border: 10px solid pink; } Am using the exact same code supplied by Mootools in their own example, if i do this on a blank webpage it works but incorporated into my own webpage, it doesn't, and my own page just have the script tag of the Jquery in the head section of the HTML.

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• LINQ and ArcObjects

  - by Marko Apfel

  Motivation LINQ (language integrated query) is a component of the Microsoft. NET Framework since version 3.5. It allows a SQL-like query to various data sources such as SQL, XML etc. Like SQL also LINQ to SQL provides a declarative notation of problem solving – i.e. you don’t need describe in detail how a task could be solved, you describe what to be solved at all. This frees the developer from error-prone iterator constructs. Ideally, of course, would be to access features with this way. Then this construct is conceivable: var largeFeatures = from feature in features where (feature.GetValue("SHAPE_Area").ToDouble() > 3000) select feature; or its equivalent as a lambda expression: var largeFeatures = features.Where(feature => (feature.GetValue("SHAPE_Area").ToDouble() > 3000)); This requires an appropriate provider, which manages the corresponding iterator logic. This is easier than you might think at first sight - you have to deliver only the desired entities as IEnumerable<IFeature>. LINQ automatically establishes a state machine in the background, whose execution is delayed (deferred execution) - when you are really request entities (foreach, Count (), ToList (), ..) an instantiation processing takes place, although it was already created at a completely different place. Especially in multiple iteration through entities in the first debuggings you are rubbing your eyes when the execution pointer jumps magically back in the iterator logic. Realization A very concise logic for constructing IEnumerable<IFeature> can be achieved by running through a IFeatureCursor. You return each feature via yield. For an easier usage I have put the logic in an extension method Getfeatures() for IFeatureClass: public static IEnumerable<IFeature> GetFeatures(this IFeatureClass featureClass, IQueryFilter queryFilter, RecyclingPolicy policy) { IFeatureCursor featureCursor = featureClass.Search(queryFilter, RecyclingPolicy.Recycle == policy); IFeature feature; while (null != (feature = featureCursor.NextFeature())) { yield return feature; } //this is skipped in unit tests with cursor-mock if (Marshal.IsComObject(featureCursor)) { Marshal.ReleaseComObject(featureCursor); } } So you can now easily generate the IEnumerable<IFeature>: IEnumerable<IFeature> features = _featureClass.GetFeatures(RecyclingPolicy.DoNotRecycle); You have to be careful with the recycling cursor. After a delayed execution in the same context it is not a good idea to re-iterated on the features. In this case only the content of the last (recycled) features is provided and all the features are the same in the second set. Therefore, this expression would be critical: largeFeatures.ToList(). ForEach(feature => Debug.WriteLine(feature.OID)); because ToList() iterates once through the list and so the the cursor was once moved through the features. So the extension method ForEach() always delivers the same feature. In such situations, you must not use a recycling cursor. Repeated executions of ForEach() is not a problem, because for every time the state machine is re-instantiated and thus the cursor runs again - that's the magic already mentioned above. Perspective Now you can also go one step further and realize your own implementation for the interface IEnumerable<IFeature>. This requires that only the method and property to access the enumerator have to be programmed. In the enumerator himself in the Reset() method you organize the re-executing of the search. This could be archived with an appropriate delegate in the constructor: new FeatureEnumerator<IFeatureclass>(_featureClass, featureClass => featureClass.Search(_filter, isRecyclingCursor)); which is called in Reset(): public void Reset() { _featureCursor = _resetCursor(_t); } In this manner, enumerators for completely different scenarios could be implemented, which are used on the client side completely identical like described above. Thus cursors, selection sets, etc. merge into a single matter and the reusability of code is increasing immensely. On top of that in automated unit tests an IEnumerable could be mocked very easily - a major step towards better software quality. Conclusion Nevertheless, caution should be exercised with these constructs in performance-relevant queries. Because of managing a state machine in the background, a lot of overhead is created. The processing costs additional time - about 20 to 100 percent. In addition, working without a recycling cursor is fast a performance gap. However declarative LINQ code is much more elegant, flawless and easy to maintain than manually iterating, compare and establish a list of results. The code size is reduced according to experience an average of 75 to 90 percent! So I like to wait a few milliseconds longer. As so often it has to be balanced between maintainability and performance - which for me is gaining in priority maintainability. In times of multi-core processors, the processing time of most business processes is anyway not dominated by code execution but by waiting for user input. Demo source code The source code for this prototype with several unit tests, you can download here: https://github.com/esride-apf/Linq2ArcObjects. .

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• Coherence Data Guarantees for Data Reads - Basic Terminology

  - by jpurdy

  When integrating Coherence into applications, each application has its own set of requirements with respect to data integrity guarantees. Developers often describe these requirements using expressions like "avoiding dirty reads" or "making sure that updates are transactional", but we often find that even in a small group of people, there may be a wide range of opinions as to what these terms mean. This may simply be due to a lack of familiarity, but given that Coherence sits at an intersection of several (mostly) unrelated fields, it may be a matter of conflicting vocabularies (e.g. "consistency" is similar but different in transaction processing versus multi-threaded programming). Since almost all data read consistency issues are related to the concept of concurrency, it is helpful to start with a definition of that, or rather what it means for two operations to be concurrent. Rather than implying that they occur "at the same time", concurrency is a slightly weaker statement -- it simply means that it can't be proven that one event precedes (or follows) the other. As an example, in a Coherence application, if two client members mutate two different cache entries sitting on two different cache servers at roughly the same time, it is likely that one update will precede the other by a significant amount of time (say 0.1ms). However, since there is no guarantee that all four members have their clocks perfectly synchronized, and there is no way to precisely measure the time it takes to send a given message between any two members (that have differing clocks), we consider these to be concurrent operations since we can not (easily) prove otherwise. So this leads to a question that we hear quite frequently: "Are the contents of the near cache always synchronized with the underlying distributed cache?". It's easy to see that if an update on a cache server results in a message being sent to each near cache, and then that near cache being updated that there is a window where the contents are different. However, this is irrelevant, since even if the application reads directly from the distributed cache, another thread update the cache before the read is returned to the application. Even if no other member modifies a cache entry prior to the local near cache entry being updated (and subsequently read), the purpose of reading a cache entry is to do something with the result, usually either displaying for consumption by a human, or by updating the entry based on the current state of the entry. In the former case, it's clear that if the data is updated faster than a human can perceive, then there is no problem (and in many cases this can be relaxed even further). For the latter case, the application must assume that the value might potentially be updated before it has a chance to update it. This almost aways the case with read-only caches, and the solution is the traditional optimistic transaction pattern, which requires the application to explicitly state what assumptions it made about the old value of the cache entry. If the application doesn't want to bother stating those assumptions, it is free to lock the cache entry prior to reading it, ensuring that no other threads will mutate the entry, a pessimistic approach. The optimistic approach relies on what is sometimes called a "fuzzy read". In other words, the application assumes that the read should be correct, but it also acknowledges that it might not be. (I use the qualifier "sometimes" because in some writings, "fuzzy read" indicates the situation where the application actually sees an original value and then later sees an updated value within the same transaction -- however, both definitions are roughly equivalent from an application design perspective). If the read is not correct it is called a "stale read". Going back to the definition of concurrency, it may seem difficult to precisely define a stale read, but the practical way of detecting a stale read is that is will cause the encompassing transaction to roll back if it tries to update that value. The pessimistic approach relies on a "coherent read", a guarantee that the value returned is not only the same as the primary copy of that value, but also that it will remain that way. In most cases this can be used interchangeably with "repeatable read" (though that term has additional implications when used in the context of a database system). In none of cases above is it possible for the application to perform a "dirty read". A dirty read occurs when the application reads a piece of data that was never committed. In practice the only way this can occur is with multi-phase updates such as transactions, where a value may be temporarily update but then withdrawn when a transaction is rolled back. If another thread sees that value prior to the rollback, it is a dirty read. If an application uses optimistic transactions, dirty reads will merely result in a lack of forward progress (this is actually one of the main risks of dirty reads -- they can be chained and potentially cause cascading rollbacks). The concepts of dirty reads, fuzzy reads, stale reads and coherent reads are able to describe the vast majority of requirements that we see in the field. However, the important thing is to define the terms used to define requirements. A quick web search for each of the terms in this article will show multiple meanings, so I've selected what are generally the most common variations, but it never hurts to state each definition explicitly if they are critical to the success of a project (many applications have sufficiently loose requirements that precise terminology can be avoided).

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• Key Windows Phone Development Concepts

  - by Tim Murphy

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

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• IsNumeric() Broken? Only up to a point.

  - by Phil Factor

  In SQL Server, probably the best-known 'broken' function is poor ISNUMERIC() . The documentation says 'ISNUMERIC returns 1 when the input expression evaluates to a valid numeric data type; otherwise it returns 0. ISNUMERIC returns 1 for some characters that are not numbers, such as plus (+), minus (-), and valid currency symbols such as the dollar sign ($).'Although it will take numeric data types (No, I don't understand why either), its main use is supposed to be to test strings to make sure that you can convert them to whatever numeric datatype you are using (int, numeric, bigint, money, smallint, smallmoney, tinyint, float, decimal, or real). It wouldn't actually be of much use anyway, since each datatype has different rules. You actually need a RegEx to do a reasonably safe check. The other snag is that the IsNumeric() function  is a bit broken. SELECT ISNUMERIC(',')This cheerfully returns 1, since it believes that a comma is a currency symbol (not a thousands-separator) and you meant to say 0, in this strange currency.  However, SELECT ISNUMERIC(N'£')isn't recognized as currency.  '+' and  '-' is seen to be numeric, which is stretching it a bit. You'll see that what it allows isn't really broken except that it doesn't recognize Unicode currency symbols: It just tells you that one numeric type is likely to accept the string if you do an explicit conversion to it using the string. Both these work fine, so poor IsNumeric has to follow suit. SELECT  CAST('0E0' AS FLOAT)SELECT  CAST (',' AS MONEY) but it is harder to predict which data type will accept a '+' sign. SELECT  CAST ('+' AS money) --0.00SELECT  CAST ('+' AS INT)   --0SELECT  CAST ('+' AS numeric)/* Msg 8115, Level 16, State 6, Line 4 Arithmetic overflow error converting varchar to data type numeric.*/SELECT  CAST ('+' AS FLOAT)/*Msg 8114, Level 16, State 5, Line 5Error converting data type varchar to float.*/> So we can begin to say that the maybe IsNumeric isn't really broken, but is answering a silly question 'Is there some numeric datatype to which i can convert this string? Almost, but not quite. The bug is that it doesn't understand Unicode currency characters such as the euro or franc which are actually valid when used in the CAST function. (perhaps they're delaying fixing the euro bug just in case it isn't necessary).SELECT ISNUMERIC (N'?23.67') --0SELECT  CAST (N'?23.67' AS money) --23.67SELECT ISNUMERIC (N'£100.20') --1SELECT  CAST (N'£100.20' AS money) --100.20 Also the CAST function itself is quirky in that it cannot convert perfectly reasonable string-representations of integers into integersSELECT ISNUMERIC('200,000')       --1SELECT  CAST ('200,000' AS INT)   --0/*Msg 245, Level 16, State 1, Line 2Conversion failed when converting the varchar value '200,000' to data type int.*/  A more sensible question is 'Is this an integer or decimal number'. This cuts out a lot of the apparent quirkiness. We do this by the '+E0' trick. If we want to include floats in the check, we'll need to make it a bit more complicated. Here is a small test-rig. SELECT  PossibleNumber,         ISNUMERIC(CAST(PossibleNumber AS NVARCHAR(20)) + 'E+00') AS Hack,        ISNUMERIC (PossibleNumber + CASE WHEN PossibleNumber LIKE '%E%'                                          THEN '' ELSE 'E+00' END) AS Hackier,        ISNUMERIC(PossibleNumber) AS RawIsNumericFROM    (SELECT CAST(',' AS NVARCHAR(10)) AS PossibleNumber          UNION SELECT '£' UNION SELECT '.'         UNION SELECT '56' UNION SELECT '456.67890'         UNION SELECT '0E0' UNION SELECT '-'         UNION SELECT '-' UNION SELECT '.'         UNION  SELECT N'?' UNION SELECT N'¢'        UNION  SELECT N'?' UNION SELECT N'?34.56'         UNION SELECT '-345' UNION SELECT '3.332228E+09') AS examples Which gives the result ... PossibleNumber Hack Hackier RawIsNumeric-------------- ----------- ----------- ------------? 0 0 0- 0 0 1, 0 0 1. 0 0 1¢ 0 0 1£ 0 0 1? 0 0 0?34.56 0 0 00E0 0 1 13.332228E+09 0 1 1-345 1 1 1456.67890 1 1 156 1 1 1 I suspect that this is as far as you'll get before you abandon IsNumeric in favour of a regex. You can only get part of the way with the LIKE wildcards, because you cannot specify quantifiers. You'll need full-blown Regex strings like these ..[-+]?\b[0-9]+(\.[0-9]+)?\b #INT or REAL[-+]?\b[0-9]{1,3}\b #TINYINT[-+]?\b[0-9]{1,5}\b #SMALLINT.. but you'll get even these to fail to catch numbers out of range.So is IsNumeric() an out and out rogue function? Not really, I'd say, but then it would need a damned good lawyer.

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• Why is jQuery so widely adopted versus other Javascript frameworks?

  - by Andrew Moore

  I manage a group of programmers. I do value my employees opinion but lately we've been divided as to which framework to use on web projects. I personally favor MooTools, but some of my team seems to want to migrate to jQuery because it is more widely adopted. That by itself is not enough for me to allow a migration. I have used both jQuery and MooTools. This particular essay tends to reflect how I feel about both frameworks. jQuery is great for DOM Manipulation, but seem to be limited to helping you do that. Feature wise, both jQuery and MooTools allow for easy DOM Selection and Manipulation: // jQuery $('#someContainer div[class~=dialog]') .css('border', '2px solid red') .addClass('critical'); // MooTools $('#someContainer div[class~=dialog]') .setStyle('border', '2px solid red') .addClass('critical'); Both jQuery and MooTools allow for easy AJAX: // jQuery $('#someContainer div[class~=dialog]') .load('/DialogContent.html'); // MooTools (Using shorthand notation, you can also use Request.HTML) $('#someContainer div[class~=dialog]') .load('/DialogContent.html'); Both jQuery and MooTools allow for easy DOM Animation: // jQuery $('#someContainer div[class~=dialog]') .animate({opacity: 1}, 500); // MooTools (Using shorthand notation, you can also use Fx.Tween). $('#someContainer div[class~=dialog]') .set('tween', {duration: 500}) .tween('opacity', 1); jQuery offers the following extras: Large community of supporters Plugin Repository Integration with Microsoft's ASP.NET and VisualStudio Used by Microsoft, Google and others MooTools offers the following extras: Object Oriented Framework with Classic OOP emulation for JS Extended native objects Higher consistency between browsers for native functions support. More easy code reuse Used by The World Wide Web Consortium, Palm and others. Given that, it seems that MooTools does everything jQuery does and more (some things I cannot do in jQuery and I can in MooTools) but jQuery has a smaller learning curve. So the question is, why did you or your team choose jQuery over another JavaScript framework? Note: While I know and admit jQuery is a great framework, there are other options around and I'm trying to take a decision as to why jQuery should be our choice versus what we use right now (MooTools)?

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• How do you override the opacity of a parent control in WPF?

  - by Metro Smurf

  When you set the opacity on a Grid in WPF, all the child elements appear to inherit its Opacity. How can you have a child element not inherit the parent's opacity? For example, the following parent grid has one child grid in the middle with a background set to red, but the background appears pinkish because of the parent's opacity. I'd like the child grid to have a solid color, non-transparent background: <Grid x:Name="LayoutRoot"> <Grid Background="Black" Opacity="0.5"> <Grid.RowDefinitions> <RowDefinition Height="0.333*"/> <RowDefinition Height="0.333*"/> <RowDefinition Height="0.333*"/> </Grid.RowDefinitions> <Grid.ColumnDefinitions> <ColumnDefinition Width="0.333*"/> <ColumnDefinition Width="0.333*"/> <ColumnDefinition Width="0.333*"/> </Grid.ColumnDefinitions> <-- how do you make this child grid's background solid red and not inherit the Opacity/Transparency of the parent grid? --> <Grid Grid.Column="1" Grid.Row="1" Background="Red"/> </Grid> </Grid>

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• Drag Panel Extender in Ajax?

  - by Surya sasidhar

  hi, i am working on dragpanel extender i write the code for drag panel, it is coming nice but when i drag the panel it going back to the same position where it is initially. This is my code... Untitled Page <style type="text/css"> .outerPanel { border: solid 1px #C0C0C0; background-color: #e1e1e1; width: 200px; height: 300px; z-index:20; padding: 2px; } .dragPanel { border: solid 1px #FFFFFF; background-color: #C0C0C0; width: 194px; height: 15px; color: #FFFFFF; font-weight:bold; padding: 2px; cursor: move; } function setBodyHeightToContentHeight() { document.body.style.height = Math.max(document.documentElement.scrollHeight, document.body.scrollHeight) + "px"; } setBodyHeightToContentHeight(); // Uncomment the line below if you are having problem while resizing the browser window. window.attachEvent('onresize', setBodyHeightToContentHeight); <asp:Panel ID="Panel1" runat="server" CssClass="outerPanel"> <asp:Panel ID="Panel2" runat="server" CssClass="dragPanel"> <b>Dragable Panel</b> </asp:Panel> <p> Surya Sasidhar surya sasidhar Surya Sasidhar surya sasidhar Surya sasidhar surya sasidhar </p> <cc1:DragPanelExtender ID="DragPanelExtender1" TargetControlID="Panel1" DragHandleID ="Panel2" runat="server"> </cc1:DragPanelExtender> </div> </form> and it is ging some javascript error like object required

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• Android Live Wallpaper: waitForCondition(ReallocateCondition)

  - by jstatz

  I've been developing a live wallpaper using GLWallpaperService, and have gotten good results overall. It runs rock-solid in the emulator and looks good. I've dealt with OpenGL many times before so have a solid command of how to do things... unfortunately I'm having a hell of a time getting this to actually be stable on the actual hardware. The basic symption occurs when you slide the physical keyboard on a Motorola Droid in and out a few times. This causes the wallpaper to get destroyed/recreated several times in quick succession -- which would be fine, as I have my assets clearing in onDestroy and reloading in onSurfaceChanged. The problem is after a few iterations of this, (four or five, maybe) the calls to onSurfaceChanged completely stop, and i get an endless string of this printed to the log: 04-02 00:53:18.088: WARN/SharedBufferStack(1032): waitForCondition(ReallocateCondition) timed out (identity=337, status=0). CPU may be pegged. trying again. Is there something I should be implementing here aside from the Android-typical onSurfaceCreated/onSurfaceChanged/onSurfaceDestroyed triumvirate? Browsing through the WallpaperService and WallpaperRenderer classes doesn't pop up anything obvious to me.

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• Javascript menu that hovers over initial element

  - by TenJack

  I'm trying to build a javascript menu using prototype that when you mouseover an element, that element is hidden and a bigger element is shown in its place that closes onmouseout. This is what I have so far to give you an idea, but it doesn't work and is buggy. I'm not sure what the best general approach is: EDIT: using the prototype refactor from remi bourgarel: function socialMenuInit(){ var social_menu = $('sociable_menu'); social_menu.hide(); var share_words = $('share_words'); Event.observe(share_words,"mouseover",function(){ share_words.hide(); social_menu.show(); }); Event.observe(social_menu,"mouseout",function(){ social_menu.hide(); share_words.show(); }); } EDIT: The main problem now is that the second bigger menu(social_menu) that is shown on top of the smaller mouseover triggering element(share_words) only closes when you mouseout the smaller trigger element even though this element is hidden. EDIT: This is the html and css I am using: <div id="share_words">share</div> <div id="sociable_menu"></div> #share_words{ display: none; border: 1px solid white; position: absolute; right: 320px; top:0px; padding: 4px; background-image: url('/images/icons/group.png'); background-repeat: no-repeat; background-position:7px 6px; text-indent:26px; color: white; z-index: 15; } #sociable_menu{ border: 1px solid black; padding: 5px; position: absolute; right: 275px; top: -10px; z-index: 20; } Thanks for any help.

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