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• How to prevent duplicate data access methods that retrieve similar data?

  - by Ronald Wildenberg

  In almost every project I work on with a team, the same problem seems to creep in. Someone writes UI code that needs data and writes a data access method: AssetDto GetAssetById(int assetId) A week later someone else is working on another part of the application and also needs an AssetDto but now including 'approvers' and writes the following: AssetDto GetAssetWithApproversById(int assetId) A month later someone needs an asset but now including the 'questions' (or the 'owners' or the 'running requests', etc): AssetDto GetAssetWithQuestionsById(int assetId) AssetDto GetAssetWithOwnersById(int assetId) AssetDto GetAssetWithRunningRequestsById(int assetId) And it gets even worse when methods like GetAssetWithOwnerAndQuestionsById start to appear. You see the pattern that emerges: an object is attached to a large object graph and you need different parts of this graph in different locations. Of course, I'd like to prevent having a large number of methods that do almost the same. Is it simply a matter of team discipline or is there some pattern I can use to prevent this? In some cases it might make sense to have separate methods, i.e. getting an asset with running requests may be expensive so I do not want to include these all the time. How to handle such cases?

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• How to avoid to be employed by companies which are candidates to DailyWTF stories?

  - by MainMa

  I'm reading The Daily WTF archives and especially those stories about IT-related companies which have a completely wrong approach of software development, the job of a developer, etc. Some stories are totally horrible: a company don't have a local network for security reasons, another one has a source control server which can only be accessed by the manager, etc. Add to it all those stories about managers who don't know anything about their work and make stupid decisions without listening to anybody. The thing is that I don't see how to know if you will be employed by such company during an interview. Of course, sometimes, an interviewer tells weird things which gives you an idea that something goes very wrong with the company (in my case, the last manager said I should work 100% of my time through Remote Desktop, connected to on an old and slooooow machine, because "it avoids several people to modify the same source code"; maybe I should explain him what SVN is). But in most cases, you will be unable to get enough information during the interview to get the exact image of a company. So how to avoid being employed by this sort of companies? I thought about asking to see some documents like documentation guide or code style guidelines. The problem is that I live in France, and here, most of the companies don't have those documents at all, and in the rare cases where those documents exist, they are outdated, poorly written, never used, or do force you to make things that don't make any sense. I also thought about asking to see how programmers actually work. But seeing that they have dual screens or "late-modern-artsy-fartsy furnishings" doesn't mean that they don't have people making weird decisions, making it impossible to work there. Have you been in such situations? What have you tried? Have it worked?

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• How to add precedence to LALR parser like in YACC?

  - by greenoldman

  Please note, I am asking about writing LALR parser, not writing rules for LALR parser. What I need is... ...to mimic YACC precedence definitions. I don't know how it is implemented, and below I describe what I've done and read so far. For now I have basic LALR parser written. Next step -- adding precedence, so 2+3*4 could be parsed as 2+(3*4). I've read about precedence parsers, however I don't see how to fit such model into LALR. I don't understand two points: how to compute when insert parenthesis generator how to compute how many parenthesis the generator should create I insert generators when the symbols is taken from input and put at the stack, right? So let's say I have something like this (| denotes boundary between stack and input): ID = 5 | + ..., at this point I add open, so it gives ID = < 5 | + ..., then I read more input ID = < 5 + | 5 ... and more ID = < 5 + 5 | ; ... and more ID = < 5 + 5 ; | ... At this point I should have several reduce moves in normal LALR, but the open parenthesis does not match so I continue reading more input. Which does not make sense. So this was when problem. And about count, let's say I have such data < 2 + < 3 * 4 >. As human I can see that the last generator should create 2 parenthesis, but how to compute this? After all there could be two scenarios: ( 2 + ( 3 *4 )) -- parenthesis is used to show the outcome of generator or (2 + (( 3 * 4 ) ^ 5) because there was more input Please note that in both cases before 3 was open generator, and after 4 there was close generator. However in both cases, after reading 4 I have to reduce, so I have to know what generator "creates".

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• Is there really anything to gain with complex design? [duplicate]

  - by SB2055

  This question already has an answer here: What is enterprise software, exactly? 8 answers I've been working for a consulting firm for some time, with clients of various sizes, and I've seen web applications ranging in complexity from really simple: MVC Service Layer EF DB To really complex: MVC UoW DI / IoC Repository Service UI Tests Unit Tests Integration Tests But on both ends of the spectrum, the quality requirements are about the same. In simple projects, new devs / consultants can hop on, make changes, and contribute immediately, without having to wade through 6 layers of abstraction to understand what's going on, or risking misunderstanding some complex abstraction and costing down the line. In all cases, there was never a need to actually make code swappable or reusable - and the tests were never actually maintained past the first iteration because requirements changed, it was too time-consuming, deadlines, business pressure, etc etc. So if - in the end - testing and interfaces aren't used rapid development (read: cost-savings) is a priority the project's requirements will be changing a lot while in development ...would it be wrong to recommend a super-simple architecture, even to solve a complex problem, for an enterprise client? Is it complexity that defines enterprise solutions, or is it the reliability, # concurrent users, ease-of-maintenance, or all of the above? I know this is a very vague question, and any answer wouldn't apply to all cases, but I'm interested in hearing from devs / consultants that have been in the business for a while and that have worked with these varying degrees of complexity, to hear if the cool-but-expensive abstractions are worth the overall cost, at least while the project is in development.

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• Outlook macro runs through 250 iterations before failing with error [migrated]

  - by Senoculus

  Description: I have an Outlook macro that loops through selected emails in a folder and writes down some info to a .csv file. It works perfectly up until 250 before failing. Here is some of the code: Open strSaveAsFilename For Append As #1 CountVar = 0 For Each objItem In Application.ActiveExplorer.Selection DoEvents If objItem.VotingResponse <> "" Then CountVar = CountVar + 1 Debug.Print " " & CountVar & ". " & objItem.SenderName Print #1, & objItem.SenderName & "," & objItem.VotingResponse Else CountVar = CountVar + 1 Debug.Print " " & CountVar & ". " & "Moving email from: " & Chr(34) & objItem.SenderName & Chr(34) & " to: Special Cases sub-folder" objItem.Move CurrentFolderVar.Folders("Special Cases") End If Next Close #1 Problem After this code runs through 250 emails, the following screenshot pops up: http://i.stack.imgur.com/yt9P8.jpg I've tried adding a "wait" function to give the server a rest so that I'm not querying it so quickly, but I get the same error at the same point.

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• How do you track existing requirements over time?

  - by CaptainAwesomePants

  I'm a software engineer working on a complex, ongoing website. It has a lot of moving parts and a small team of UI designers and business folks adding new features and tweaking old ones. Over the last year or so, we've added hundreds of interesting little edge cases. Planning, implementing, and testing them is not a problem. The problem comes later, when we want to refactor or add another new feature. Nobody remembers half of the old features and edge cases from a year ago. When we want to add a new change, we notice that code does all sorts of things in there, and we're not entirely sure which things are intentional requirements and which are meaningless side effects. Did someone last year request that the login token was supposed to only be valid for 30 minutes, or did some programmers just pick a sensible default? Can we change it? Back when the product was first envisioned, we created some documentation describing how the site worked. Since then we created a few additional documents describing new features, but nobody ever goes back and updates those documents when new features are requested, so the only authoritative documentation is the code itself. But the code provides no justification, no reason for its actions: only the how, never the why. What do other long-running teams do to keep track of what the requirements were and why?

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• Dealing with Fine-Grained Cache Entries in Coherence

  - by jpurdy

  On occasion we have seen significant memory overhead when using very small cache entries. Consider the case where there is a small key (say a synthetic key stored in a long) and a small value (perhaps a number or short string). With most backing maps, each cache entry will require an instance of Map.Entry, and in the case of a LocalCache backing map (used for expiry and eviction), there is additional metadata stored (such as last access time). Given the size of this data (usually a few dozen bytes) and the granularity of Java memory allocation (often a minimum of 32 bytes per object, depending on the specific JVM implementation), it is easily possible to end up with the case where the cache entry appears to be a couple dozen bytes but ends up occupying several hundred bytes of actual heap, resulting in anywhere from a 5x to 10x increase in stated memory requirements. In most cases, this increase applies to only a few small NamedCaches, and is inconsequential -- but in some cases it might apply to one or more very large NamedCaches, in which case it may dominate memory sizing calculations. Ultimately, the requirement is to avoid the per-entry overhead, which can be done either at the application level by grouping multiple logical entries into single cache entries, or at the backing map level, again by combining multiple entries into a smaller number of larger heap objects. At the application level, it may be possible to combine objects based on parent-child or sibling relationships (basically the same requirements that would apply to using partition affinity). If there is no natural relationship, it may still be possible to combine objects, effectively using a Coherence NamedCache as a "map of maps". This forces the application to first find a collection of objects (by performing a partial hash) and then to look within that collection for the desired object. This is most naturally implemented as a collection of entry processors to avoid pulling unnecessary data back to the client (and also to encapsulate that logic within a service layer). At the backing map level, the NIO storage option keeps keys on heap, and so has limited benefit for this situation. The Elastic Data features of Coherence naturally combine entries into larger heap objects, with the caveat that only data -- and not indexes -- can be stored in Elastic Data.

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• Mechanics of reasoning during programming interviews

  - by user129506

  This is not the usual "I don't want to write code during an interview", in this question the assumption is that I need to write code during an interview (think about the level of rewriting the quicksort or mergesort from scratch) I know how the algorithm work or I have a basic idea of how I should start working from there, i.e. I don't remember the algorithm by heart I noticed that even on a whiteboard, I always end up writing bugged code or code that doesn't compile. If there's a typo, whatever I usually live with that.. but when there's a crash due to some uncaught particular case I end up losing confidence in my skills. I realize that perhaps interviewers might want to look at how I write code and/or how I solve problems rather than proof-compiling my whiteboard code, but I'd like to ask how should I approach the above problem in mental terms, i.e. what mental steps should I follow when writing code for an interview with the two bullet points above. There must be a unique and agreed series of steps I should follow to avoid getting stuck/caught into particular exception cases (limit cases) that might end up wasting my time and my energies rather than focusing on the overall algorithm for the general case. I hope I made my point clear

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• Do you write unit tests for all the time in TDD?

  - by mcaaltuntas

  I have been designing and developing code with TDD style for a long time. What disturbs me about TDD is writing tests for code that does not contain any business logic or interesting behaviour. I know TDD is a design activity more than testing but sometimes I feel it's useless to write tests in these scenarios. For example I have a simple scenario like "When user clicks check button, it should check file's validity". For this scenario I usually start writing tests for presenter/controller class like the one below. @Test public void when_user_clicks_check_it_should_check_selected_file_validity(){ MediaService service =mock(MediaService); View view =mock(View); when(view.getSelectedFile).thenReturns("c:\\Dir\\file.avi"); MediaController controller =new MediaController(service,view); controller.check(); verify(service).check("c:\\Dir\\file.avi"); } As you can see there is no design decision or interesting code to verify behaviour. I am testing values from view passed to MediaService. I usually write but don't like these kind of tests. What do yo do about these situations ? Do you write tests for all the time ? UPDATE : I have changed the test name and code after complaints. Some users said that you should write tests for the trivial cases like this so in the future someone might add interesting behaviour. But what about “Code for today, design for tomorrow.” ? If someone, including myself, adds more interesting code in the future the test can be created for it then. Why should I do it now for the trivial cases ?

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• Please recommend the best tools to build a test plan management tool

  - by fzkl

  I have mostly worked on hardware testing in my professional career and would like to get onto the software development side. I thought working on a practically usable project will help motivate me and help acquire some skills. I have decided to build a test plan management tool for the QA team I work in (We use excel sheets!). The test plan management tool should be browser based and should support this: There would be many test plans, each test plan having test sets, test sets having test cases and test cases having instructions, attachments and Pass/fail status marking and bug info in case of failure. It should also have an export to excel option. I have a visual picture of the tool I am looking to build but I don't have enough experience to figure our where to start. My current programming skills are limited to C and shell programming and I want to pick up python. What tools (programming language, database and anything else?) would you recommend for me to get this done? Also what are the key concepts in the recommended programming language that I should focus on to build a browser based tool like this?

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• What makes you look like a bad developer (ie a hacker) [on hold]

  - by user134583

  This comes from a lot of people about me, so I have to look at myself. So I would wonder what make one a bad developer (ie a hacker). These are a few things about me I used IDE intensively, all features, you name it: auto-completion, refactoring, quick fixes, open type, view hierarchy, API documentation, etcc When I deal with writing code for a project in domain I am not used to (I can't have fluency in this, this is new), I only have a very rough high level ideas. I don't use the standard modeling diagrams for early detail planning. Unorthodox diagrams that I invented when I need to draw the design in details. I don't use UML or similar, I find them not enough. I divide the sorts of diagram I drew into 3 types. Very high level diagrams which probably can be understood by almost anybody. Data entity diagram used for modeling data objects only (like ER diagrams and tree for inheritances and composition). Action diagrams for agents/classes and their interactions on data objects they contain. Constantly changing the interface (public methods) between interacting agents/classes if the need arises. I am more refrained when the interface and the module have matured Write initial concept code in a quick hackie way just so that the module works in the general cases so that I can play around with it. The module will be re-factored intensively after playing around so I could see more corner cases that I couldn't or (wouldn't want) anticipate before writing code. Using JUnit for integration-like test by using TestSuite class and ordering Unit test classes in the suite Using debugger almost anytime there is a problem instead of reading the code Constantly search on the internet for how to do some thing with some library that I haven't used a lot. So judgment, am I a bad developer? a hacker? Put in other words, to make sure this is not considered off-topic: - Is this bad practice to make your code too agile during incubating/prototyping phase of software development - Is it bad practice to use JUnit for integration testing, (I know there are other framework for integration testing, but those frameworks are for a specific products, not general)

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• In developing a soap client proxy, which return structure is easier to use and more sensible?

  - by cori

  I'm writing (in PHP) a client/proxy for a SOAP web service. The return types are consistently wrapped in response objects that contain the return values. In many cases this make a lot of sense - for instance when multiple values are being returned: GetDetailsResponse Object ( Results Object ( [TotalResults] => 10 [NextPage] => 2 ) [Details] => Array ( [0] => Detail Object ( [Id] => 1 ) ) ) But some of the methods return a single scalar value or a single object or array wrapped in a response object: GetThingummyIdResponse Object ( [ThingummyId] => 42 ) In some cases these objects might be pretty deep, so getting at properties within requires drilling down several layers: $response->Details->Detail[0]->Contents->Item[5]->Id And if I unwrap them before passing them back I can strip out a layer from consumers' code. I know I'm probably being a little bit of an Architecture Astronaut here, but the latter style really bug me, so I've been working through my code to have my proxy methods just return the scalar value to the client code where there's no absolute need for a wrapper object. My question is, am I actually making things more difficult for the consumers of my code? Would I be better off just leaving the return values wrapped in response objects so that everything is consistent, or is removing unneccessary layers of indirection/abstraction worthwhile?

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• Why using Fragments?

  - by ahmed_khan_89

  I have read the documentation and some other questions' threads about this topic and I don't really feel convinced; I don't see clearly the limits of use of this technique. Fragments are now seen as a Best Practice; every Activity should be basically a support for one or more Fragments and not call a layout directly. Fragments are created in order to: allow the Activity to use many fragments, to change between them, to reuse these units... == the Fragment is totally dependent to the Context of an activity , so if I need something generic that I can reuse and handle in many Activities, I can create my own custom layouts or Views ... I will not care about this additional Complexity Developing Layer that fragments would add. a better handling to different resolution == OK for tablets/phones in case of long process that we can show two (or more) fragments in the same Activity in Tablets, and one by one in phones. But why would I use fragments always ? handling callbacks to navigate between Fragments (i.e: if the user is Logged-in I show a fragment else I show another fragment). === Just try to see how many bugs facebook SDK Log-in have because of this, to understand that it is really (?) ... considering that an Android Application is based on Activities... Adding another life cycles in the Activity would be better to design an Application... I mean the modules, the scenarios, the data management and the connectivity would be better designed, in that way. === This is an answer of someone who's used to see the Android SDK and Android Framework with a Fragments vision. I don't think it's wrong, but I am not sure it will give good results... And it is really abstract... ==== Why would I complicate my life, coding more, in using them always? else, why is it a best practice if it's just a tool for some cases? what are these cases?

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• Replacement for Picasa [closed]

  - by January

  Possible Duplicate: What is the best alternative to Picasa? I use Picasa not because it is a great photo manager -- it's not, the manager is "sort of OK" for my taste. However, it combines a passable photo manager with a good "quick and dirty" image editor. It has the basic functions like cropping, resizing, contrast and color adjustment, and the one great feature -- "I'm feeling lucky" button, that works in 90% of the cases. Also, from time to time, I use one or two of the effects (like saturation or sharpening). GIMP is great and I use it on a regular basis, but in most cases I just want to go quickly through the photographs of my kids birthday and make them more presentable without much fuss. I'm looking for a native, open source replacement, something that would not miss the editing capabilities of Picasa and would allow me to quickly go through a collection of photographs and make basic edits. A function similar to "I'm feeling lucky" (automatic adjustment of contrast, color and brightness) would be most welcome. EDIT: Yes, I have already tried a number of alternatives, if it is necessary I can produce a detailed list here, along with the problems I found. I'm posting that question because I hope to see a new name.

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• New MySQL Cluster 7.3 Previews: Foreign Keys, NoSQL Node.js API and Auto-Tuned Clusters

  - by Mat Keep

  At this weeks MySQL Connect conference, Oracle previewed an exciting new wave of developments for MySQL Cluster, further extending its simplicity and flexibility by expanding the range of use-cases, adding new NoSQL options, and automating configuration. What’s new: Development Release 1: MySQL Cluster 7.3 with Foreign Keys Early Access “Labs” Preview: MySQL Cluster NoSQL API for Node.js Early Access “Labs” Preview: MySQL Cluster GUI-Based Auto-Installer In this blog, I'll introduce you to the features being previewed. Review the blogs listed below for more detail on each of the specific features discussed. Save the date!: A live webinar is scheduled for Thursday 25th October at 0900 Pacific Time / 1600UTC where we will discuss each of these enhancements in more detail. Registration will be open soon and published to the MySQL webinars page MySQL Cluster 7.3: Development Release 1 The first MySQL Cluster 7.3 Development Milestone Release (DMR) previews Foreign Keys, bringing powerful new functionality to MySQL Cluster while eliminating development complexity. Foreign Key support has been one of the most requested enhancements to MySQL Cluster – enabling users to simplify their data models and application logic – while extending the range of use-cases for both custom projects requiring referential integrity and packaged applications, such as eCommerce, CRM, CMS, etc. Implementation The Foreign Key functionality is implemented directly within the MySQL Cluster data nodes, allowing any client API accessing the cluster to benefit from them – whether they are SQL or one of the NoSQL interfaces (Memcached, C++, Java, JPA, HTTP/REST or the new Node.js API - discussed later.) The core referential actions defined in the SQL:2003 standard are implemented: CASCADE RESTRICT NO ACTION SET NULL In addition, the MySQL Cluster implementation supports the online adding and dropping of Foreign Keys, ensuring the Cluster continues to serve both read and write requests during the operation.  This represents a further enhancement to MySQL Cluster's support for on0line schema changes, ie adding and dropping indexes, adding columns, etc.  Read this blog for a demonstration of using Foreign Keys with MySQL Cluster.  Getting Started with MySQL Cluster 7.3 DMR1: Users can download either the source or binary and evaluate the MySQL Cluster 7.3 DMR with Foreign Keys now! (Select the Development Release tab). MySQL Cluster NoSQL API for Node.js Node.js is hot! In a little over 3 years, it has become one of the most popular environments for developing next generation web, cloud, mobile and social applications. Bringing JavaScript from the browser to the server, the design goal of Node.js is to build new real-time applications supporting millions of client connections, serviced by a single CPU core. Making it simple to further extend the flexibility and power of Node.js to the database layer, we are previewing the Node.js Javascript API for MySQL Cluster as an Early Access release, available for download now from http://labs.mysql.com/. Select the following build: MySQL-Cluster-NoSQL-Connector-for-Node-js Alternatively, you can clone the project at the MySQL GitHub page.  Implemented as a module for the V8 engine, the new API provides Node.js with a native, asynchronous JavaScript interface that can be used to both query and receive results sets directly from MySQL Cluster, without transformations to SQL. Figure 1: MySQL Cluster NoSQL API for Node.js enables end-to-end JavaScript development Rather than just presenting a simple interface to the database, the Node.js module integrates the MySQL Cluster native API library directly within the web application itself, enabling developers to seamlessly couple their high performance, distributed applications with a high performance, distributed, persistence layer delivering 99.999% availability. The new Node.js API joins a rich array of NoSQL interfaces available for MySQL Cluster. Whichever API is chosen for an application, SQL and NoSQL can be used concurrently across the same data set, providing the ultimate in developer flexibility.  Get started with MySQL Cluster NoSQL API for Node.js tutorial MySQL Cluster GUI-Based Auto-Installer Compatible with both MySQL Cluster 7.2 and 7.3, the Auto-Installer makes it simple for DevOps teams to quickly configure and provision highly optimized MySQL Cluster deployments – whether on-premise or in the cloud. Implemented with a standard HTML GUI and Python-based web server back-end, the Auto-Installer intelligently configures MySQL Cluster based on application requirements and auto-discovered hardware resources Figure 2: Automated Tuning and Configuration of MySQL Cluster Developed by the same engineering team responsible for the MySQL Cluster database, the installer provides standardized configurations that make it simple, quick and easy to build stable and high performance clustered environments. The auto-installer is previewed as an Early Access release, available for download now from http://labs.mysql.com/, by selecting the MySQL-Cluster-Auto-Installer build. You can read more about getting started with the MySQL Cluster auto-installer here. Watch the YouTube video for a demonstration of using the MySQL Cluster auto-installer Getting Started with MySQL Cluster If you are new to MySQL Cluster, the Getting Started guide will walk you through installing an evaluation cluster on a singe host (these guides reflect MySQL Cluster 7.2, but apply equally well to 7.3 and the Early Access previews). Or use the new MySQL Cluster Auto-Installer! Download the Guide to Scaling Web Databases with MySQL Cluster (to learn more about its architecture, design and ideal use-cases). Post any questions to the MySQL Cluster forum where our Engineering team and the MySQL Cluster community will attempt to assist you. Post any bugs you find to the MySQL bug tracking system (select MySQL Cluster from the Category drop-down menu) And if you have any feedback, please post them to the Comments section here or in the blogs referenced in this article. Summary MySQL Cluster 7.2 is the GA, production-ready release of MySQL Cluster. The first Development Release of MySQL Cluster 7.3 and the Early Access previews give you the opportunity to preview and evaluate future developments in the MySQL Cluster database, and we are very excited to be able to share that with you. Let us know how you get along with MySQL Cluster 7.3, and other features that you want to see in future releases, by using the comments of this blog.

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• Comments on Comments

  - by Joe Mayo

  I almost tweeted a reply to Capar Kleijne's question about comments on Twitter, but realized that my opinion exceeded 140 characters. The following is based upon my experience with extremes and approaches that I find useful in code comments. There are a couple extremes that I've seen and reasons why people go the distance in each approach. The most common extreme is no comments in the code at all.  A few bad reasons why this happens is because a developer is in a hurry, sloppy, or is interested in job preservation. The unfortunate result is that the code is difficult to understand and hard to maintain. The drawbacks to no comments in code are a primary reason why teachers drill the need for commenting code into our heads.  This viewpoint assumes the lack of comments are bad because the code is bad, but there is another reason for not commenting that is gaining more popularity. I've heard/and read that code should be self documenting. Following this thought pattern, if code is well written with meaningful names, there should not be a reason for comments.  An addendum to this argument is that comments are often neglected and get out-of-date, but the code is what is kept up-to-date. Presumably, if code contained very good naming, it would be easy to maintain.  This is a noble perspective and I like the practice of meaningful naming of identifiers. However, I think it's also an extreme approach that doesn't cover important cases.  i.e. If an identifier is named badly (subjective differences in opinion) or not changed appropriately during maintenance, then the badly named identifier is no more useful than a stale comment. These were the two no-comment extremes, so let's look at the too many comments extreme. On a regular basis, I'll see cases where the code is over-commented; not nearly as often as the no-comment scenarios, but still prevalent.  These are examples of where every single line in the code is commented.  These comments make the code harder to read because they get in the way of the algorithm.  In most cases, the comments parrot what each line of code does.  If a developer understands the language, then most statements are immediately intuitive.  i.e. what use is it to say that I'm assigning foo to bar when it's clear what the code is doing. I think that over-commenting code is a waste of time that slows down initial development and maintenance.  Understandably, the developer's intentions are admirable because they've had it beaten into their heads that they must comment. However, I think it's an extreme and prefer a more moderate approach. I don't think the extremes do justice to code because each can make maintenance harder.  No comments on bad code is obviously a problem, but the other two extremes are subtle and require qualification to address properly. The problem I see with the code-as-documentation approach is that it doesn't lift the developer out of the algorithm to identify dependencies, intentions, and hacks. Any developer can read code and follow an algorithm, but they still need to know where it fits into the big picture of the application. Because of indirections with language features like interfaces, delegates, and virtual members, code can become complex.  Occasionally, it's useful to point out a nuance or reason why a piece of code is there. i.e. If you've building an app that communicates via HTTP, you'll have certain headers to include for the endpoint, and it could be useful to point out why the code for setting those header values is there and how they affect the application. An argument against this could be that you should extract that code into a separate method with a meaningful name to describe the scenario.  My problem with such an approach would be that your code base becomes even more difficult to navigate and work with because you have all of this extra code just to make the code more meaningful. My opinion is that a simple and well-stated comment stating the reasons and intention for the code is more natural and convenient to the initial developer and maintainer.  I just don't agree with the approach of going out of the way to avoid making a comment.  I'm also concerned that some developers would take this approach as an excuse to not comment their bad code. Another area where I like comments is on documentation comments.  Java has it and so does C# and VB.  It's convenient because we can build automated tools that extract these comments.  These extracted comments are often much better than no documentation at all.  The "go read the code" answer always doesn't fulfill the need for a quick summary of an API. To summarize, I think that the extremes of no comments and too many comments are less than desirable approaches. I prefer documentation comments to explain each class and member (API level) and code comments as necessary to supplement well-written code. Joe

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• Social Business Forum Milano: Day 2

  - by me

  @YourService. The business world has flipped and small business can capitalize  by Frank Eliason (twitter: @FrankEliason ) Technology and social media tools have made it easier than ever for companies to communicate with consumers. They can listen and join in on conversations, solve problems, get instant feedback about their products and services, and more. So why, then, are most companies not doing this? Instead, it seems as if customer service is at an all time low, and that the few companies who are choosing to focus on their customers are experiencing a great competitive advantage. At Your Service explains the importance of refocusing your business on your customers and your employees, and just how to do it. Explains how to create a culture of empowered employees who understand the value of a great customer experience Advises on the need to communicate that experience to their customers and potential customers Frank Eliason, recognized by BusinessWeek as the 'most famous customer service manager in the US, possibly in the world,' has built a reputation for helping large businesses improve the way they connect with customers and enhance their relationships Quotes from the Audience: Bertrand Duperrin ?@bduperrin social service is not about shutting up the loudest cutsomers ! #sbf12 @frankeliason Paolo Pelloni ?@paolopelloniGautam Ghosh ?@GautamGhosh RT @cecildijoux: #sbf12 @frankeliason you need to change things and fix the approach it's not about social media it's about driving change  Peter H. Reiser ?@peterreiser #sbf12 Company Experience = Product Experience + Customer Interactions + Employee Experience @yourservice Engage or lose! Socialize, mobilize, conversify: engage your employees to improve business performance Christian Finn (twitter: @cfinn) First Christian was presenting the flying monkey   Then he outlined the four principals to fix the Intranet: 1. Socalize the Intranet 2. Get Thee to a Single Repository 3. Mobilize the Intranet 4. Conversationalize Your Processes Quotes from the Audience: Oscar Berg ?@oscarberg Engaged employees think their work bring out the best of their ideas @cfinn #sbf12 http://pic.twitter.com/68eddp48 John Stepper ?@johnstepper I like @cfinn's "conversify your processes" A nice related concept to "narrating your work", part of working out loud. http://johnstepper.com/2012/05/26/working-out-loud-your-personal-content-strategy/ Oscar Berg ?@oscarberg Organizations are talent markets - socializing your intranet makes this market function better @cfinn #sbf12 For profit, productivity, and personal benefit: creating a collaborative culture at Deutsche Bank John Stepper (twitter:@johnstepper) Driving adoption of collaboration + social media platforms at Deutsche Bank. John shared some great best practices on how to deploy an enterprise wide  community model  in a large company. He started with the most important question What is the commercial value of adding social ? Then he talked about the success of Community of Practices deployment and outlined some key use cases including the relevant measures to proof the ROI of the investment. Examples:  Community of practice -> measure: systematic collection of value stories  Self-service website  -> measure: based on representative models Optimizing asset inventory - > measure: Actual counts  This use case was particular interesting.  It is a crowd sourced spending/saving of infrastructure model.  User can cancel IT services they don't need (as example Software xx).  5% of the saving goes to social responsibility projects. The John outlined some  best practices on how to address the WIIFM (What's In It For Me) question of the individual users:  - change from hierarchy to graph -  working out loud = observable work + narrating  your work  - add social skills to career objectives - example: building a purposeful social network course/training as part of the job development curriculum And last but not least John gave some important tips on how to get senior management buy-in by establishing management sponsored division level collaboration boards which defines clear uses cases and measures. This divisional use cases are then implemented using a common social platform.  Thanks John - I learned a lot from your presentation!   Quotes from the Audience: Ana Silva ?@AnaDataGirl #sbf12 what's in it for individuals at Deutsche Bank? Shapping their reputations in a big org says @johnstepper #e20Ana Silva ?@AnaDataGirl Any reason why not? MT @magatorlibero #sbf12 is Deutsche B. experience on applying social inside company applicable to Italian people? Oscar Berg ?@oscarberg Your career is not a ladder, it is a network that opens up opportunities - @johnstepper #sbf12 Oscar Berg ?@oscarberg @johnstepper: Institutionalizing collaboration is next - collaboration woven into the fabric of daily work #sbf12 Ana Silva ?@AnaDataGirl #sbf12 @johnstepper talking about how Deutsche Bank is using #socbiz to build purposeful CoP & save money

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• Oracle ATG Web Commerce 10 Implementation Developer Boot Camp - Reading (UK) - October 1-12, 2012

  - by Richard Lefebvre

  REGISTER NOW: Oracle ATG Web Commerce 10 Implementation Developer Boot Camp Reading, UK, October 1-12, 2012! OPN invites you to join us for a 10-day implementation bootcamp on Oracle ATG Web Commerce in Reading, UK from October 1-12, 2012.This 10-day boot camp is designed to provide partners with hands-on experience and technical training to successfully build and deploy Oracle ATG Web Commerce 10 Applications. This particular boot camp is focused on helping partners develop the essential skills needed to implement every aspect of an ATG Commerce Application from scratch, (not CRS-based), with a specific goal of enabling experienced Java/J2EE developers with a path towards becoming functional, effective, and contributing members of an ATG implementation team. Built for both new and experienced ATG developers alike, the collaborative nature of this program and its exercises, have proven to be highly effective and extremely valuable in learning the best practices for implementing ATG solutions. Though not required, this bootcamp provides a structured path to earning a Certified Oracle ATG Web Commerce 10 Specialization! What Is Covered: This boot camp is for Application Developers and Software Architects wanting to gain valuable insight into ATG application development best practices, as well as relevant and applicable implementation experience on projects modeled after four of the most common types of applications built on the ATG platform. The following learning objectives are all critical, and are of equal priority in enabling this role to succeed. This learning boot camp will help with: Building a basic functional transaction-ready ATG Web Commerce 10 Application. Utilizing ATG’s platform features such as scenarios, slots, targeters, user profiles and segments, to create a personalized user experience. Building Nucleus components to support and/or extend application functionality. Understanding the intricacies of ATG order checkout and fulfillment. Specifying, designing and implementing new commerce features in ATG 10. Building a functional commerce application modeled after four of the most common types of applications built on the ATG platform, within an agile-based project team environment and under simulated real-world project conditions. Duration: The Oracle ATG Web Commerce 10 Implementation Developer Boot Camp is an instructor-led workshop spanning 10 days. Audience: Application Developers Software Architects Prerequisite Training and Environment Requirements: Programming and Markup Experience with Java J2EE, JavaScript, XML, HTML and CSS Completion of Oracle ATG Web Commerce 10 Implementation Specialist Development Guided Learning Path modules Participants will be required to bring their own laptop that meets the minimum specifications:   64-bit PC and OS (e.g. Windows 7 64-bit) 4GB RAM or more 40GB Hard Disk Space Laptops will require access to the Internet through Remote Desktop via Windows. Agenda Topics: Week 1 – Day 1 through 5 Build a Basic Commerce Application In week one of the boot camp training, we will apply knowledge learned from the ATG Web Commerce 10 Implementation Developer Guided Learning Path modules, towards building a basic transaction-ready commerce application. There will be little to no lectures delivered in this boot camp, as developers will be fully engaged in ATG Application Development activities and best practices. Developers will work independently on the following lab assignments from day's 1 through 5: Lab Assignments  1 Environment Setup 2 Build a dynamic Home Page 3 Site Authentication 4 Build Customer Registration 5 Display Top Level Categories 6 Display Product Sub-Categories 7 Display Product List Page 8 Display Product Detail Page 9 ATG Inventory 10 Build “Add to Cart” Functionality 11 Build Shopping Cart 12 Build Checkout Page  13 Build Checkout Review Page 14 Create an Order and Build Order Confirmation Page 15 Implement Slots and Targeters for Personalization 16 Implement Pricing and Promotions 17 Order Fulfillment Back to top Week 2 – Day 6 through 10 Team-based Case Project In the second week of the boot camp training, participants will be asked to join a project team that will select a case project for the team to implement. Teams will be able to choose from four of the most common application types developed and deployed on the ATG platform. They are as follows: Hard goods with physical fulfillment, Soft goods with electronic fulfillment, a Service or subscription case example, a Course/Event registration case example. Team projects will have approximately 160 hours of use cases/stories for each team to build (40 hours per developer). Each day's Use Cases/Stories will build upon the prior day's work, and therefore must be fully completed at the end of each day. Please note that this boot camp intends to simulate real-world project conditions, and as such will likely require the need for project teams to possibly work beyond normal business hours. To promote further collaboration and group learning, each team will be asked to present their work and share the methodologies and solutions that they've applied to their cases at the end of each day. Location: Oracle Reading CVC TPC510 Room: Wraysbury Reading, UK 9:00 AM – 5:00 PM  Registration Fee (10 Days): US $3,375 Please click on the following link to REGISTER or  visit the Oracle ATG Web Commerce 10 Implementation Developer Boot Camp page for more information. Questions: Patrick Ty Partner Enablement, Oracle Commerce Phone: 310.343.7687 Mobile: 310.633.1013 Email: [email protected]

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• Towards an F# .NET Reflector add-in

  - by CliveT

  When I had the opportunity to spent some time during Red Gate's recent "down tools" week on a project of my choice, the obvious project was an F# add-in for Reflector . To be honest, this was a bit of a misnomer as the amount of time in the designated week for coding was really less than three days, so it was always unlikely that very much progress would be made in such a small amount of time (and that certainly proved to be the case), but I did learn some things from the experiment. Like lots of problems, one useful technique is to take examples, get them to work, and then generalise to get something that works across the board. Unfortunately, I didn't have enough time to do the last stage. The obvious first step is to take a few function definitions, starting with the obvious hello world, moving on to a non-recursive function and finishing with the ubiquitous recursive Fibonacci function. let rec printMessage message  =     printfn  message let foo x  =    (x + 1) let rec fib x  =     if (x >= 2) then (fib (x - 1) + fib (x - 2)) else 1 The major problem in decompiling these simple functions is that Reflector has an in-memory object model that is designed to support object-oriented languages. In particular it has a return statement that allows function bodies to finish early. I used some of the in-built functionality to take the IL and produce an in-memory object model for the language, but then needed to write a transformer to push the return statements to the top of the tree to make it easy to render the code into a functional language. This tree transform works in some scenarios, but not in others where we simply regenerate code that looks more like CPS style. The next thing to get working was library level bindings of values where these values are calculated at runtime. let x = [1 ; 2 ; 3 ; 4] let y = List.map  (fun x -> foo x) x The way that this is translated into a set of classes for the underlying platform means that the code needs to follow references around, from the property exposing the calculated value to the class in which the code for generating the value is embedded. One of the strongest selling points of functional languages is the algebraic datatypes, which allow definitions via standard mathematical-style inductive definitions across the union cases. type Foo =     | Something of int     | Nothing type 'a Foo2 =     | Something2 of 'a     | Nothing2 Such a definition is compiled into a number of classes for the cases of the union, which all inherit from a class representing the type itself. It wasn't too hard to get such a de-compilation happening in the cases I tried. What did I learn from this? Firstly, that there are various bits of functionality inside Reflector that it would be useful for us to allow add-in writers to access. In particular, there are various implementations of the Visitor pattern which implement algorithms such as calculating the number of references for particular variables, and which perform various substitutions which could be more generally useful to add-in writers. I hope to do something about this at some point in the future. Secondly, when you transform a functional language into something that runs on top of an object-based platform, you lose some fidelity in the representation. The F# compiler leaves attributes in place so that tools can tell which classes represent classes from the source program and which are there for purposes of the implementation, allowing the decompiler to regenerate these constructs again. However, decompilation technology is a long way from being able to take unannotated IL and transform it into a program in a different language. For a simple function definition, like Fibonacci, I could write a simple static function and have it come out in F# as the same function, but it would be practically impossible to take a mass of class definitions and have a decompiler translate it automatically into an F# algebraic data type. What have we got out of this? Some data on the feasibility of implementing an F# decompiler inside Reflector, though it's hard at the moment to say how long this would take to do. The work we did is included the 6.5 EAP for Reflector that you can get from the EAP forum. All things considered though, it was a useful way to gain more familiarity with the process of writing an add-in and understand difficulties other add-in authors might experience. If you'd like to check out a video of Down Tools Week, click here.

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• Stumbling Through: Making a case for the K2 Case Management Framework

  I have recently attended a three-day training session on K2s Case Management Framework (CMF), a free framework built on top of K2s blackpearl workflow product, and I have come away with several different impressions for some of the different aspects of the framework.  Before we get into the details, what is the Case Management Framework?  It is essentially a suite of tools that, when used together, solve many common workflow scenarios.  The tool has been developed over time by K2 consultants that have realized they tend to solve the same problems over and over for various clients, so they attempted to package all of those common solutions into one framework.  Most of these common problems involve workflow process that arent necessarily direct and would tend to be difficult to model.  Such solutions could be achieved in blackpearl alone, but the workflows would be complex and difficult to follow and maintain over time.  CMF attempts to simplify such scenarios not so much by black-boxing the workflow processes, but by providing different points of entry to the processes allowing them to be simpler, moving the complexity to a middle layer.  It is not a solution in and of itself, development is still required to tie the pieces together. CMF is under continuous development, both a plus and a minus in that bugs are fixed quickly and features added regularly, but it may be difficult to know which versions are the most stable.  CMF is not an officially supported K2 product, which means you will not get technical support but you will get access to the source code. The example given of a business process that would fit well into CMF is that of a file cabinet, where each folder in said file cabinet is a case that contains all of the data associated with one complaint/customer/incident/etc. and various users can access that case at any time and take one of a set of pre-determined actions on it.  When I was given that example, my first thought was that any workflow I have ever developed in the past could be made to fit this model there must be more than just this model to help decide if CMF is the right solution.  As the training went on, we learned that one of the key features of CMF is SharePoint integration as each case gets a SharePoint site created for it, and there are a number of excellent web parts that can be used to design a portal for users to get at all the information on their cases.  While CMF does not require SharePoint, without it you will be missing out on a huge portion of functionality that CMF offers.  My opinion is that without SharePoint integration, you may as well write your workflows and other components the old fashioned way. When I heard that each case gets its own SharePoint site created for it, warning bells immediately went off in my head as I felt that depending on the data load, a CMF enabled solution could quickly overwhelm SharePoint with thousands of sites so we have yet another deciding factor for CMF:  Just how many cases will your solution be creating?  While it is not necessary to use the site-per-case model, it is one of the more useful parts of the framework.  Without it, you are losing a big chunk of what CMF has to offer. When it comes to developing on top of the Case Management Framework, it becomes a matter of configuring what makes up a case, what can be done to a case, where each action on a case should take the user, and then typing up actions to case statuses.  This last step is one that I immediately warmed up to, as just about every workflow Ive designed in the past needed some sort of mapping table to set the status of a work item based on the action being taken definitely one of those common solutions that it is good to see rolled up into a re-useable entity (and it gets a nice configuration UI to boot!).  This concept is a little different than traditional workflow design, in that you dont have to think of an end-to-end process around passing a case along a path, rather, you must envision the case as central object with workflow threads branching off of it and doing their own thing with the case data.  Certainly there can be certain workflow threads that get rather complex, but the idea is that they RELATE to the case, they dont BECOME the case (though it is still possible with action->status mappings to prevent certain actions in certain cases, so it isnt always a wide-open free for all of actions on a case). I realize that this description of the Case Management Framework merely scratches the surface on what the product actually can do, and I dont think Ive conclusively defined for what sort of business scenario you can make a case for Case Management Framework.  What I do hope to have accomplished with this post is to raise awareness of CMF there is a (free!) product out there that could potentially simplify a tangled workflow process and give (for free!) a very useful set of SharePoint web parts and a nice set of (free!) reports.  The best way to see if it will truly fit your needs is to give it a try did I mention it is FREE?  Er, ok, so it is free, but only obtainable at this time for K2 partnersDid you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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• Data Source Security Part 5

  - by Steve Felts

  If you read through the first four parts of this series on data source security, you should be an expert on this focus area.  There is one more small topic to cover related to WebLogic Resource permissions.  After that comes the test, I mean example, to see with a real set of configuration parameters what the results are with some concrete values. WebLogic Resource Permissions All of the discussion so far has been about database credentials that are (eventually) used on the database side.  WLS has resource credentials to control what WLS users are allowed to access JDBC resources.  These can be defined on the Policies tab on the Security tab associated with the data source.  There are four permissions: “reserve” (get a new connection), “admin”, “shrink”, and reset (plus the all-inclusive “ALL”); we will focus on “reserve” here because we are talking about getting connections.  By default, JDBC resource permissions are completely open – anyone can do anything.  As soon as you add one policy for a permission, then all other users are restricted.  For example, if I add a policy so that “weblogic” can reserve a connection, then all other users will fail to reserve connections unless they are also explicitly added.  The validation is done for WLS user credentials only, not database user credentials.  Configuration of resources in general is described at “Create policies for resource instances” http://docs.oracle.com/cd/E24329_01/apirefs.1211/e24401/taskhelp/security/CreatePoliciesForResourceInstances.html.  This feature can be very useful to restrict what code and users can get to your database. There are the three use cases: API Use database credentials User for permission checking getConnection() True or false Current WLS user getConnection(user,password) False User/password from API getConnection(user,password) True Current WLS user If a simple getConnection() is used or database credentials are enabled, the current user that is authenticated to the WLS system is checked. If database credentials are not enabled, then the user and password on the API are used. Example The following is an actual example of the interactions between identity-based-connection-pooling-enabled, oracle-proxy-session, and use-database-credentials. On the database side, the following objects are configured.- Database users scott; jdbcqa; jdbcqa3- Permission for proxy: alter user jdbcqa3 grant connect through jdbcqa;- Permission for proxy: alter user jdbcqa grant connect through jdbcqa; The following WebLogic Data Source objects are configured.- Users weblogic, wluser- Credential mapping “weblogic” to “scott”- Credential mapping "wluser" to "jdbcqa3"- Data source descriptor configured with user “jdbcqa”- All tests are run with Set Client ID set to true (more about that below).- All tests are run with oracle-proxy-session set to false (more about that below). The test program:- Runs in servlet- Authenticates to WLS as user “weblogic” Use DB Credentials Identity based getConnection(scott,***) getConnection(weblogic,***) getConnection(jdbcqa3,***) getConnection()  true  true Identity scottClient weblogicProxy null weblogic fails - not a db user User jdbcqa3Client weblogicProxy null Default user jdbcqaClient weblogicProxy null  false  true scott fails - not a WLS user User scottClient scottProxy null jdbcqa3 fails - not a WLS user User scottClient scottProxy null  true  false Proxy for scott fails weblogic fails - not a db user User jdbcqa3Client weblogicProxy jdbcqa Default user jdbcqaClient weblogicProxy null  false  false scott fails - not a WLS user Default user jdbcqaClient scottProxy null jdbcqa3 fails - not a WLS user Default user jdbcqaClient scottProxy null If Set Client ID is set to false, all cases would have Client set to null. If this was not an Oracle thin driver, the one case with the non-null Proxy in the above table would throw an exception because proxy session is only supported, implicitly or explicitly, with the Oracle thin driver. When oracle-proxy-session is set to true, the only cases that will pass (with a proxy of "jdbcqa") are the following.1. Setting use-database-credentials to true and doing getConnection(jdbcqa3,…) or getConnection().2. Setting use-database-credentials to false and doing getConnection(wluser, …) or getConnection(). Summary There are many options to choose from for data source security.  Considerations include the number and volatility of WLS and Database users, the granularity of data access, the depth of the security identity (property on the connection or a real user), performance, coordination of various components in the software stack, and driver capabilities.  Now that you have the big picture (remember that table in part 1), you can make a more informed choice.

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• Navigation in a #WP7 application with MVVM Light

  - by Laurent Bugnion

  In MVVM applications, it can be a bit of a challenge to send instructions to the view (for example a page) from a viewmodel. Thankfully, we have good tools at our disposal to help with that. In his excellent series “MVVM Light Toolkit soup to nuts”, Jesse Liberty proposes one approach using the MVVM Light messaging infrastructure. While this works fine, I would like to show here another approach using what I call a “view service”, i.e. an abstracted service that is invoked from the viewmodel, and implemented on the view. Multiple kinds of view services In fact, I use view services quite often, and even started standardizing them for the Windows Phone 7 applications I work on. If there is interest, I will be happy to show other such view services, for example Animation services, responsible to start/stop animations on the view. Dialog service, in charge of displaying messages to the user and gathering feedback. Navigation service, in charge of navigating to a given page directly from the viewmodel. In this article, I will concentrate on the navigation service. The INavigationService interface In most WP7 apps, the navigation service is used in quite a straightforward way. We want to: Navigate to a given URI. Go back. Be notified when a navigation is taking place, and be able to cancel. The INavigationService interface is quite simple indeed: public interface INavigationService { event NavigatingCancelEventHandler Navigating; void NavigateTo(Uri pageUri); void GoBack(); } Obviously, this interface can be extended if necessary, but in most of the apps I worked on, I found that this covers my needs. The NavigationService class It is possible to nicely pack the navigation service into its own class. To do this, we need to remember that all the PhoneApplicationPage instances use the same instance of the navigation service, exposed through their NavigationService property. In fact, in a WP7 application, it is the main frame (RootFrame, of type PhoneApplicationFrame) that is responsible for this task. So, our implementation of the NavigationService class can leverage this. First the class will grab the PhoneApplicationFrame and store a reference to it. Also, it registers a handler for the Navigating event, and forwards the event to the listening viewmodels (if any). Then, the NavigateTo and the GoBack methods are implemented. They are quite simple, because they are in fact just a gateway to the PhoneApplicationFrame. The whole class is as follows: public class NavigationService : INavigationService { private PhoneApplicationFrame _mainFrame; public event NavigatingCancelEventHandler Navigating; public void NavigateTo(Uri pageUri) { if (EnsureMainFrame()) { _mainFrame.Navigate(pageUri); } } public void GoBack() { if (EnsureMainFrame() && _mainFrame.CanGoBack) { _mainFrame.GoBack(); } } private bool EnsureMainFrame() { if (_mainFrame != null) { return true; } _mainFrame = Application.Current.RootVisual as PhoneApplicationFrame; if (_mainFrame != null) { // Could be null if the app runs inside a design tool _mainFrame.Navigating += (s, e) => { if (Navigating != null) { Navigating(s, e); } }; return true; } return false; } } Exposing URIs I find that it is a good practice to expose each page’s URI as a constant. In MVVM Light applications, a good place to do that is the ViewModelLocator, which already acts like a central point of setup for the views and their viewmodels. Note that in some cases, it is necessary to expose the URL as a string, for instance when a query string needs to be passed to the view. So for example we could have: public static readonly Uri MainPageUri = new Uri("/MainPage.xaml", UriKind.Relative); public const string AnotherPageUrl = "/AnotherPage.xaml?param1={0}&param2={1}"; Creating and using the NavigationService Normally, we only need one instance of the NavigationService class. In cases where you use an IOC container, it is easy to simply register a singleton instance. For example, I am using a modified version of a super simple IOC container, and so I can register the navigation service as follows: SimpleIoc.Register<INavigationService, NavigationService>(); Then, it can be resolved where needed with: SimpleIoc.Resolve<INavigationService>(); Or (more frequently), I simply declare a parameter on the viewmodel constructor of type INavigationService and let the IOC container do its magic and inject the instance of the NavigationService when the viewmodel is created. On supported platforms (for example Silverlight 4), it is also possible to use MEF. Or, of course, we can simply instantiate the NavigationService in the ViewModelLocator, and pass this instance as a parameter of the viewmodels’ constructor, injected as a property, etc… Once the instance has been passed to the viewmodel, it can be used, for example with: NavigationService.NavigateTo(ViewModelLocator.ComparisonPageUri); Testing Thanks to the INavigationService interface, navigation can be mocked and tested when the viewmodel is put under unit test. Simply implement and inject a mock class, and assert that the methods are called as they should by the viewmodel. Conclusion As usual, there are multiple ways to code a solution answering your needs. I find that view services are a really neat way to delegate view-specific responsibilities such as animation, dialogs and of course navigation to other classes through an abstracted interface. In some cases, such as the NavigationService class exposed here, it is even possible to standardize the implementation and pack it in a class library for reuse. I hope that this sample is useful! Happy coding. Laurent   Laurent Bugnion (GalaSoft) Subscribe | Twitter | Facebook | Flickr | LinkedIn

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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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• Ninject & Entity Framework =(sometimes) "The ObjectContext instance has been disposed ..."

  - by n26

  I am using Ninject and ADO.Net Entity Framework in my Aps.Net (Mvc) website. I bind the ObjectContext to Ninject using the RequestScope: Bind<Entities>().ToSelf().InRequestScope().WithConstructorArgument("connectionString", _connectionString); In most cases this works perferct. But sometimes I got the following error: The ObjectContext instance has been disposed and can no longer be used for operations that require a connection. This error occurs at different positions while getting, updating, inserting or deleting data. In some cases this error occurs until I reset my webapp and sometimes it disappears after some requests. I am displeased that I have no more details. Because it seems that there is no pattern when and where this error occurs. Because the time and position is allways different :( Some hints or ideas?

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• <msbuild/> task fails while <devenv/> succeeds for MFC application in CruiseControl.NET?

  - by ee

  The Overview I am working on a Continuous Integration build of a MFC appliction via CruiseControl.net and VS2010. When building my .sln, a "Visual Studio" CCNet task (<devenv/>) works, but a simple MSBuild wrapper script (see below) run via the CCNet <msbuild/> task fails with errors like: error RC1015: cannot open include file 'winres.h'.. error C1083: Cannot open include file: 'afxwin.h': No such file or directory error C1083: Cannot open include file: 'afx.h': No such file or directory The Question How can I adjust the build environment of my msbuild wrapper so that the application builds correctly? (Pretty clearly the MFC paths aren't right for the msbuild environment, but how do i fix it for MSBuild+VS2010+MFC+CCNet?) Background Details We have successfully upgraded an MFC application (.exe with some MFC extension .dlls) to Visual Studio 2010 and can compile the application without issue on developer machines. Now I am working on compiling the application on the CI server environment I did a full installation of VS2010 (Professional) on the build server. In this way, I knew everything I needed would be on the machine (one way or another) and that this would be consistent with developer machines. VS2010 is correctly installed on the CI server, and the devenv task works as expected I now have a wrapper MSBuild script that does some extended version processing and then builds the .sln for the application via an MSBuild task. This wrapper script is run via CCNet's MSBuild task and fails with the above mentioned errors The Simple MSBuild Wrapper <?xml version="1.0" encoding="utf-8"?> <Project ToolsVersion="4.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003"> <Target Name="Build"> <!-- Doing some versioning stuff here--> <MSBuild Projects="target.sln" Properties="Configuration=ReleaseUnicode;Platform=Any CPU;..." /> </Target> </Project> My Assumptions This seems to be a missing/wrong configuration of include paths to standard header resources of the MFC persuasion I should be able to coerce the MSBuild environment to consider the relevant resource files from my VS2010 install and have this approach work. Given the vs2010 msbuild support for visual c++ projects (.vcxproj), shouldn't msbuilding a solution be pretty close to compiling via visual studio? But how do I do that? Am I setting Environment variables? Registry settings? I can see how one can inject additional directories in some cases, but this seems to need a more systemic configuration at the compiler defaults level. Update 1 This appears to only ever happen in two cases: resource compilation (rc.exe), and precompiled header (stdafx.h) compilation, and only for certain projects? I was thinking it was across the board, but indeed it appears only to be in these cases. I guess I will keep digging and hope someone has some insight they would be willing to share...

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