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• Combining Shared Secret and Username Token – Azure Service Bus

  - by Michael Stephenson

  As discussed in the introduction article this walkthrough will explain how you can implement WCF security with the Windows Azure Service Bus to ensure that you can protect your endpoint in the cloud with a shared secret but also flow through a username token so that in your listening WCF service you will be able to identify who sent the message. This could either be in the form of an application or a user depending on how you want to use your token. Prerequisites Before going into the walk through I want to explain a few assumptions about the scenario we are implementing but to keep the article shorter I am not going to walk through all of the steps in how to setup some of this. In the solution we have a simple console application which will represent the client application. There is also the services WCF application which contains the WCF service we will expose via the Windows Azure Service Bus. The WCF Service application in this example was hosted in IIS 7 on Windows 2008 R2 with AppFabric Server installed and configured to auto-start the WCF listening services. I am not going to go through significant detail around the IIS setup because it should not matter in relation to this article however if you want to understand more about how to configure WCF and IIS for such a scenario please refer to the following paper which goes into a lot of detail about how to configure this. The link is: http://tinyurl.com/8s5nwrz   The Service Component To begin with let's look at the service component and how it can be configured to listen to the service bus using a shared secret but to also accept a username token from the client. In the sample the service component is called Acme.Azure.ServiceBus.Poc.UN.Services. It has a single service which is the Visual Studio template for a WCF service when you add a new WCF Service Application so we have a service called Service1 with its Echo method. Nothing special so far!.... The next step is to look at the web.config file to see how we have configured the WCF service. In the services section of the WCF configuration you can see I have created my service and I have created a local endpoint which I simply used to do a little bit of diagnostics and to check it was working, but more importantly there is the Windows Azure endpoint which is using the ws2007HttpRelayBinding (note that this should also work just the same if your using netTcpRelayBinding). The key points to note on the above picture are the service behavior called MyServiceBehaviour and the service bus endpoints behavior called MyEndpointBehaviour. We will go into these in more detail later.   The Relay Binding The relay binding for the service has been configured to use the TransportWithMessageCredential security mode. This is the important bit where the transport security really relates to the interaction between the service and listening to the Azure Service Bus and the message credential is where we will use our username token like we have specified in the message/clientCrentialType attribute. Note also that we have left the relayClientAuthenticationType set to RelayAccessToken. This means that authentication will be made against ACS for accessing the service bus and messages will not be accepted from any sender who has not been authenticated by ACS.   The Endpoint Behaviour In the below picture you can see the endpoint behavior which is configured to use the shared secret client credential for accessing the service bus and also for diagnostic purposes I have included the service registry element. Hopefully if you are familiar with using Windows Azure Service Bus relay feature the above is very familiar to you and this is a very common setup for this section. There is nothing specific to the username token implementation here. The Service Behaviour Now we come to the bit with most of the username token bits in it. When you configure the service behavior I have included the serviceCredentials element and then setup to use userNameAuthentication and you can see that I have created my own custom username token validator.   This setup means that WCF will hand off to my class for validating the username token details. I have also added the serviceSecurityAudit element to give me a simple auditing of access capability. My UsernamePassword Validator The below picture shows you the details of the username password validator class I have implemented. WCF will hand off to this class when validating the token and give me a nice way to check the token credentials against an on-premise store. You have all of the validation features with a non-service bus WCF implementation available such as validating the username password against active directory or ASP.net membership features or as in my case above something much simpler.   The Client Now let's take a look at the client side of this solution and how we can configure the client to authenticate against ACS but also send a username token over to the service component so it can implement additional security checks on-premise. I have a console application and in the program class I want to use the proxy generated with Add Service Reference to send a message via the Azure Service Bus. You can see in my WCF client configuration below I have setup my details for the azure service bus url and am using the ws2007HttpRelayBinding. Next is my configuration for the relay binding. You can see below I have configured security to use TransportWithMessageCredential so we will flow the username token with the message and also the RelayAccessToken relayClientAuthenticationType which means the component will validate against ACS before being allowed to access the relay endpoint to send a message.     After the binding we need to configure the endpoint behavior like in the below picture. This is the normal configuration to use a shared secret for accessing a Service Bus endpoint.   Finally below we have the code of the client in the console application which will call the service bus. You can see that we have created our proxy and then made a normal call to a WCF service but this time we have also set the ClientCredentials to use the appropriate username and password which will be flown through the service bus and to our service which will validate them.     Conclusion As you can see from the above walkthrough it is not too difficult to configure a service to use both a shared secret and username token at the same time. This gives you the power and protection offered by the access control service in the cloud but also the ability to flow additional tokens to the on-premise component for additional security features to be implemented. Sample The sample used in this post is available at the following location: https://s3.amazonaws.com/CSCBlogSamples/Acme.Azure.ServiceBus.Poc.UN.zip

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• How Mature is Your Database Change Management Process?

  - by Ben Rees

  .dbd-banner p{ font-size:0.75em; padding:0 0 10px; margin:0 } .dbd-banner p span{ color:#675C6D; } .dbd-banner p:last-child{ padding:0; } @media ALL and (max-width:640px){ .dbd-banner{ background:#f0f0f0; padding:5px; color:#333; margin-top: 5px; } } -- Database Delivery Patterns & Practices Further Reading Organization and team processes How do you get your database schema changes live, on to your production system? As your team of developers and DBAs are working on the changes to the database to support your business-critical applications, how do these updates wend their way through from dev environments, possibly to QA, hopefully through pre-production and eventually to production in a controlled, reliable and repeatable way? In this article, I describe a model we use to try and understand the different stages that customers go through as their database change management processes mature, from the very basic and manual, through to advanced continuous delivery practices. I also provide a simple chart that will help you determine “How mature is our database change management process?” This process of managing changes to the database – which all of us who have worked in application/database development have had to deal with in one form or another – is sometimes known as Database Change Management (even if we’ve never used the term ourselves). And it’s a difficult process, often painfully so. Some developers take the approach of “I’ve no idea how my changes get live – I just write the stored procedures and add columns to the tables. It’s someone else’s problem to get this stuff live. I think we’ve got a DBA somewhere who deals with it – I don’t know, I’ve never met him/her”. I know I used to work that way. I worked that way because I assumed that making the updates to production was a trivial task – how hard can it be? Pause the application for half an hour in the middle of the night, copy over the changes to the app and the database, and switch it back on again? Voila! But somehow it never seemed that easy. And it certainly was never that easy for database changes. Why? Because you can’t just overwrite the old database with the new version. Databases have a state – more specifically 4Tb of critical data built up over the last 12 years of running your business, and if your quick hotfix happened to accidentally delete that 4Tb of data, then you’re “Looking for a new role” pretty quickly after the failed release. There are a lot of other reasons why a managed database change management process is important for organisations, besides job security, not least: Frequency of releases. Many business managers are feeling the pressure to get functionality out to their users sooner, quicker and more reliably. The new book (which I highly recommend) Lean Enterprise by Jez Humble, Barry O’Reilly and Joanne Molesky provides a great discussion on how many enterprises are having to move towards a leaner, more frequent release cycle to maintain their competitive advantage. It’s no longer acceptable to release once per year, leaving your customers waiting all year for changes they desperately need (and expect) Auditing and compliance. SOX, HIPAA and other compliance frameworks have demanded that companies implement proper processes for managing changes to their databases, whether managing schema changes, making sure that the data itself is being looked after correctly or other mechanisms that provide an audit trail of changes. We’ve found, at Red Gate that we have a very wide range of customers using every possible form of database change management imaginable. Everything from “Nothing – I just fix the schema on production from my laptop when things go wrong, and write it down in my notebook” to “A full Continuous Delivery process – any change made by a dev gets checked in and recorded, fully tested (including performance tests) before a (tested) release is made available to our Release Management system, ready for live deployment!”. And everything in between of course. Because of the vast number of customers using so many different approaches we found ourselves struggling to keep on top of what everyone was doing – struggling to identify patterns in customers’ behavior. This is useful for us, because we want to try and fit the products we have to different needs – different products are relevant to different customers and we waste everyone’s time (most notably, our customers’) if we’re suggesting products that aren’t appropriate for them. If someone visited a sports store, looking to embark on a new fitness program, and the store assistant suggested the latest $10,000 multi-gym, complete with multiple weights mechanisms, dumb-bells, pull-up bars and so on, then he’s likely to lose that customer. All he needed was a pair of running shoes! To solve this issue – in an attempt to simplify how we understand our customers and our offerings – we built a model. This is a an attempt at trying to classify our customers in to some sort of model or “Customer Maturity Framework” as we rather grandly term it, which somehow simplifies our understanding of what our customers are doing. The great statistician, George Box (amongst other things, the “Box” in the Box-Jenkins time series model) gave us the famous quote: “Essentially all models are wrong, but some are useful” We’ve taken this quote to heart – we know it’s a gross over-simplification of the real world of how users work with complex legacy and new database developments. Almost nobody precisely fits in to one of our categories. But we hope it’s useful and interesting. There are actually a number of similar models that exist for more general application delivery. We’ve found these from ThoughtWorks/Forrester, from InfoQ and others, and initially we tried just taking these models and replacing the word “application” for “database”. However, we hit a problem. From talking to our customers we know that users are far less further down the road of mature database change management than they are for application development. As a simple example, no application developer, who wants to keep his/her job would develop an application for an organisation without source controlling that code. Sure, he/she might not be using an advanced Gitflow branching methodology but they’ll certainly be making sure their code gets managed in a repo somewhere with all the benefits of history, auditing and so on. But this certainly isn’t the case (yet) for the database – a very large segment of the people we speak to have no source control set up for their databases whatsoever, even at the most basic level (for example, keeping change scripts in a source control system somewhere). By the way, if this is you, Red Gate has a great whitepaper here, on the barriers people face getting a source control process implemented at their organisations. This difference in maturity is the same as you move in to areas such as continuous integration (common amongst app developers, relatively rare for database developers) and automated release management (growing amongst app developers, very rare for the database). So, when we created the model we started from scratch and biased the levels of maturity towards what we actually see amongst our customers. But, what are these stages? And what level are you? The table below describes our definitions for four levels of maturity – Baseline, Beginner, Intermediate and Advanced. As I say, this is a model – you won’t fit any of these categories perfectly, but hopefully one will ring true more than others. We’ve also created a PDF with a flow chart to help you find which of these groups most closely matches your team:  Download the Database Delivery Maturity Framework PDF here   Level D1 – Baseline Work directly on live databases Sometimes work directly in production Generate manual scripts for releases. Sometimes use a product like SQL Compare or similar to do this Any tests that we might have are run manually Level D2 – Beginner Have some ad-hoc DB version control such as manually adding upgrade scripts to a version control system Attempt is made to keep production in sync with development environments There is some documentation and planning of manual deployments Some basic automated DB testing in process Level D3 – Intermediate The database is fully version-controlled with a product like Red Gate SQL Source Control or SSDT Database environments are managed Production environment schema is reproducible from the source control system There are some automated tests Have looked at using migration scripts for difficult database refactoring cases Level D4 – Advanced Using continuous integration for database changes Build, testing and deployment of DB changes carried out through a proper database release process Fully automated tests Production system is monitored for fast feedback to developers   Does this model reflect your team at all? Where are you on this journey? We’d be very interested in knowing how you get on. We’re doing a lot of work at the moment, at Red Gate, trying to help people progress through these stages. For example, if you’re currently not source controlling your database, then this is a natural next step. If you are already source controlling your database, what about the next stage – continuous integration and automated release management? To help understand these issues, there’s a summary of the Red Gate Database Delivery learning program on our site, alongside a Patterns and Practices library here on Simple-Talk and a Training Academy section on our documentation site to help you get up and running with the tools you need to progress. All feedback is welcome and it would be great to hear where you find yourself on this journey! This article is part of our database delivery patterns & practices series on Simple Talk. Find more articles for version control, automated testing, continuous integration & deployment.

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• Book Review: Brownfield Application Development in .NET

  - by DotNetBlues

  I recently finished reading the book Brownfield Application Development in .NET by Kyle Baley and Donald Belcham.  The book is available from Manning.  First off, let me say that I'm a huge fan of Manning as a publisher.  I've found their books to be top-quality, over all.  As a Kindle owner, I also appreciate getting an ebook copy along with the dead tree copy.  I find ebooks to be much more convenient to read, but hard-copies are easier to reference. The book covers, surprisingly enough, working with brownfield applications.  Which is well and good, if that term has meaning to you.  It didn't for me.  Without retreading a chunk of the first chapter, the authors break code bases into three broad categories: greenfield, brownfield, and legacy.  Greenfield is, essentially, new development that hasn't had time to rust and is (hopefully) being approached with some discipline.  Legacy applications are those that are more or less stable and functional, that do not expect to see a lot of work done to them, and are more likely to be replaced than reworked. Brownfield code is the gray (brown?) area between the two and the authors argue, quite effectively, that it is the most likely state for an application to be in.  Brownfield code has, in some way, been allowed to tarnish around the edges and can be difficult to work with.  Although I hadn't realized it, most of the code I've worked on has been brownfield.  Sometimes, there's talk of scrapping and starting over.  Sometimes, the team dismisses increased discipline as ivory tower nonsense.  And, sometimes, I've been the ignorant culprit vexing my future self. The book is broken into two major sections, plus an introduction chapter and an appendix.  The first section covers what the authors refer to as "The Ecosystem" which consists of version control, build and integration, testing, metrics, and defect management.  The second section is on actually writing code for brownfield applications and discusses object-oriented principles, architecture, external dependencies, and, of course, how to deal with these when coming into an existing code base. The ecosystem section is just shy of 140 pages long and brings some real meat to the matter.  The focus on "pain points" immediately sets the tone as problem-solution, rather than academic.  The authors also approach some of the topics from a different angle than some essays I've read on similar topics.  For example, the chapter on automated testing is on just that -- automated testing.  It's all well and good to criticize a project as conflating integration tests with unit tests, but it really doesn't make anyone's life better.  The discussion on testing is more focused on the "right" level of testing for existing projects.  Sometimes, an integration test is the best you can do without gutting a section of functional code.  Even if you can sell other developers and/or management on doing so, it doesn't actually provide benefit to your customers to rewrite code that works.  This isn't to say the authors encourage sloppy coding.  Far from it.  Just that they point out the wisdom of ignoring the sleeping bear until after you deal with the snarling wolf. The other sections take a similarly real-world, workable approach to the pain points they address.  As the section moves from technical solutions like version control and continuous integration (CI) to the softer, process issues of metrics and defect tracking, the authors begin to gently suggest moving toward a zero defect count.  While that really sounds like an unreasonable goal for a lot of ongoing projects, it's quite apparent that the authors have first-hand experience with taming some gruesome projects.  The suggestions are grounded and workable, and the difficulty of some situations is explicitly acknowledged. I have to admit that I started getting bored by the end of the ecosystem section.  No matter how valuable I think a good project manager or business analyst is to a successful ALM, at the end of the day, I'm a gear-head.  Also, while I agreed with a lot of the ecosystem ideas, in theory, I didn't necessarily feel that a lot of the single-developer projects that I'm often involved in really needed that level of rigor.  It's only after reading the sidebars and commentary in the coding section that I had the context for the arguments made in favor of a strong ecosystem supporting the development process.  That isn't to say that I didn't support good product management -- indeed, I've probably pushed too hard, on occasion, for a strong ALM outside of just development.  This book gave me deeper insight into why some corners shouldn't be cut and how damaging certain sins of omission can be. The code section, though, kept me engaged for its entirety.  Many technical books can be used as reference material from day one.  The authors were clear, however, that this book is not one of these.  The first chapter of the section (chapter seven, over all) addresses object oriented (OO) practices.  I've read any number of definitions, discussions, and treatises on OO.  None of the chapter was new to me, but it was a good review, and I'm of the opinion that it's good to review the foundations of what you do, from time to time, so I didn't mind. The remainder of the book is really just about how to apply OOP to existing code -- and, just because all your code exists in classes does not mean that it's object oriented.  That topic has the potential to be extremely condescending, but the authors miraculously managed to never once make me feel like a dolt or that they were wagging their finger at me for my prior sins.  Instead, they continue the "pain points" and problem-solution presentation to give concrete examples of how to apply some pretty academic-sounding ideas.  That's a point worth emphasizing, as my experience with most OO discussions is that they stay in the academic realm.  This book gives some very, very good explanations of why things like the Liskov Substitution Principle exist and why a corporate programmer should even care.  Even if you know, with absolute certainty, that you'll never have to work on an existing code-base, I would recommend this book just for the clarity it provides on OOP. This book goes beyond just theory, or even real-world application.  It presents some methods for fixing problems that any developer can, and probably will, encounter in the wild.  First, the authors address refactoring application layers and internal dependencies.  Then, they take you through those layers from the UI to the data access layer and external dependencies.  Finally, they come full circle to tie it all back to the overall process.  By the time the book is done, you're left with a lot of ideas, but also a reasonable plan to begin to improve an existing project structure. Throughout the book, it's apparent that the authors have their own preferred methodology (TDD and domain-driven design), as well as some preferred tools.  The "Our .NET Toolbox" is something of a neon sign pointing to that latter point.  They do not beat the reader over the head with anything resembling a "One True Way" mentality.  Even for the most emphatic points, the tone is quite congenial and helpful.  With some of the near-theological divides that exist within the tech community, I found this to be one of the more remarkable characteristics of the book.  Although the authors favor tools that might be considered Alt.NET, there is no reason the advice and techniques given couldn't be quite successful in a pure Microsoft shop with Team Foundation Server.  For that matter, even though the book specifically addresses .NET, it could be applied to a Java and Oracle shop, as well.

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• Variant Management– Which Approach fits for my Product?

  - by C. Chadwick

  Jürgen Kunz – Director Product Development – Oracle ORACLE Deutschland B.V. & Co. KG Introduction In a difficult economic environment, it is important for companies to understand the customer requirements in detail and to address them in their products. Customer specific products, however, usually cause increased costs. Variant management helps to find the best combination of standard components and custom components which balances customer’s product requirements and product costs. Depending on the type of product, different approaches to variant management will be applied. For example the automotive product “car” or electronic/high-tech products like a “computer”, with a pre-defined set of options to be combined in the individual configuration (so called “Assembled to Order” products), require a different approach to products in heavy machinery, which are (at least partially) engineered in a customer specific way (so-called “Engineered-to Order” products). This article discusses different approaches to variant management. Starting with the simple Bill of Material (BOM), this article presents three different approaches to variant management, which are provided by Agile PLM. Single level BOM and Variant BOM The single level BOM is the basic form of the BOM. The product structure is defined using assemblies and single parts. A particular product is thus represented by a fixed product structure. As soon as you have to manage product variants, the single level BOM is no longer sufficient. A variant BOM will be needed to manage product variants. The variant BOM is sometimes referred to as 150% BOM, since a variant BOM contains more parts and assemblies than actually needed to assemble the (final) product – just 150% of the parts You can evolve the variant BOM from the single level BOM by replacing single nodes with a placeholder node. The placeholder in this case represents the possible variants of a part or assembly. Product structure nodes, which are part of any product, are so-called “Must-Have” parts. “Optional” parts can be omitted in the final product. Additional attributes allow limiting the quantity of parts/assemblies which can be assigned at a certain position in the Variant BOM. Figure 1 shows the variant BOM of Agile PLM. Figure 1 Variant BOM in Agile PLM During the instantiation of the Variant BOM, the placeholders get replaced by specific variants of the parts and assemblies. The selection of the desired or appropriate variants is either done step by step by the user or by applying pre-defined configuration rules. As a result of the instantiation, an independent BOM will be created (Figure 2). Figure 2 Instantiated BOM in Agile PLM This kind of Variant BOM  can be used for „Assembled –To-Order“ type products as well as for „Engineered-to-Order“-type products. In case of “Assembled –To-Order” type products, typically the instantiation is done automatically with pre-defined configuration rules. For „Engineered- to-Order“-type products at least part of the product is selected manually to make use of customized parts/assemblies, that have been engineered according to the specific custom requirements. Template BOM The Template BOM is used for „Engineered-to-Order“-type products. It is another type of variant BOM. The engineer works in a flexible environment which allows him to build the most creative solutions. At the same time the engineer shall be guided to re-use existing solutions and it shall be assured that product variants of the same product family share the same base structure. The template BOM defines the basic structure of products belonging to the same product family. Let’s take a gearbox as an example. The customer specific configuration of the gearbox is influenced by several parameters (e.g. rpm range, transmitted torque), which are defined in the customer’s requirement document.  Figure 3 shows part of a Template BOM (yellow) and its relation to the product family hierarchy (blue).  Figure 3 Template BOM Every component of the Template BOM has links to the variants that have been engineeried so far for the component (depending on the level in the Template BOM, they are product variants, Assembly Variant or single part variants). This library of solutions, the so-called solution space, can be used by the engineers to build new product variants. In the best case, the engineer selects an existing solution variant, such as the gearbox shown in figure 3. When the existing variants do not fulfill the specific requirements, a new variant will be engineered. This new variant must be compliant with the given Template BOM. If we look at the gearbox in figure 3  it must consist of a transmission housing, a Connecting Plate, a set of Gears and a Planetary transmission – pre-assumed that all components are must have components. The new variant will enhance the solution space and is automatically available for re-use in future variants. The result of the instantiation of the Template BOM is a stand-alone BOM which represents the customer specific product variant. Modular BOM The concept of the modular BOM was invented in the automotive industry. Passenger cars are so-called „Assembled-to-Order“-products. The customer first selects the specific equipment of the car (so-called specifications) – for instance engine, audio equipment, rims, color. Based on this information the required parts will be determined and the customer specific car will be assembled. Certain combinations of specification are not available for the customer, because they are not feasible from technical perspective (e.g. a convertible with sun roof) or because the combination will not be offered for marketing reasons (e.g. steel rims with a sports line car). The modular BOM (yellow structure in figure 4) is defined in the context of a specific product family (in the sample it is product family „Speedstar“). It is the same modular BOM for the different types of cars of the product family (e.g. sedan, station wagon). The assembly or single parts of the car (blue nodes in figure 4) are assigned at the leaf level of the modular BOM. The assignment of assembly and parts to the modular BOM is enriched with a configuration rule (purple elements in figure 4). The configuration rule defines the conditions to use a specific assembly or single part. The configuration rule is valid in the context of a type of car (green elements in figure 4). Color specific parts are assigned to the color independent parts via additional configuration rules (grey elements in figure 4). The configuration rules use Boolean operators to connect the specifications. Additional consistency rules (constraints) may be used to define invalid combinations of specification (so-called exclusions). Furthermore consistency rules may be used to add specifications to the set of specifications. For instance it is important that a car with diesel engine always is build using the high capacity battery.  Figure 4 Modular BOM The calculation of the car configuration consists of several steps. First the consistency rules (constraints) are applied. Resulting from that specification might be added automatically. The second step will determine the assemblies and single parts for the complete structure of the modular BOM, by evaluating the configuration rules in the context of the current type of car. The evaluation of the rules for one component in the modular BOM might result in several rules being fulfilled. In this case the most specific rule (typically the longest rule) will win. Thanks to this approach, it is possible to add a specific variant to the modular BOM without the need to change any other configuration rules.  As a result the whole set of configuration rules is easy to maintain. Finally the color specific assemblies respective parts will be determined and the configuration is completed. Figure 5 Calculated Car Configuration The result of the car configuration is shown in figure 5. It shows the list of assemblies respective single parts (blue components in figure 5), which are required to build the customer specific car. Summary There are different approaches to variant management. Three different approaches have been presented in this article. At the end of the day, it is the type of the product which decides about the best approach.  For „Assembled to Order“-type products it is very likely that you can define the configuration rules and calculate the product variant automatically. Products of type „Engineered-to-Order“ ,however, need to be engineered. Nevertheless in the majority of cases, part of the product structure can be generated automatically in a similar way to „Assembled to Order“-tape products.  That said it is important first to analyze the product portfolio, in order to define the best approach to variant management.

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• Real tortoises keep it slow and steady. How about the backups?

  - by Maria Zakourdaev

    … Four tortoises were playing in the backyard when they decided they needed hibiscus flower snacks. They pooled their money and sent the smallest tortoise out to fetch the snacks. Two days passed and there was no sign of the tortoise. "You know, she is taking a lot of time", said one of the tortoises. A little voice from just out side the fence said, "If you are going to talk that way about me I won't go." Is it too much to request from the quite expensive 3rd party backup tool to be a way faster than the SQL server native backup? Or at least save a respectable amount of storage by producing a really smaller backup files?  By saying “really smaller”, I mean at least getting a file in half size. After Googling the internet in an attempt to understand what other “sql people” are using for database backups, I see that most people are using one of three tools which are the main players in SQL backup area:  LiteSpeed by Quest SQL Backup by Red Gate SQL Safe by Idera The feedbacks about those tools are truly emotional and happy. However, while reading the forums and blogs I have wondered, is it possible that many are accustomed to using the above tools since SQL 2000 and 2005.  This can easily be understood due to the fact that a 300GB database backup for instance, using regular a SQL 2005 backup statement would have run for about 3 hours and have produced ~150GB file (depending on the content, of course).  Then you take a 3rd party tool which performs the same backup in 30 minutes resulting in a 30GB file leaving you speechless, you run to management persuading them to buy it due to the fact that it is definitely worth the price. In addition to the increased speed and disk space savings you would also get backup file encryption and virtual restore -  features that are still missing from the SQL server. But in case you, as well as me, don’t need these additional features and only want a tool that performs a full backup MUCH faster AND produces a far smaller backup file (like the gain you observed back in SQL 2005 days) you will be quite disappointed. SQL Server backup compression feature has totally changed the market picture. Medium size database. Take a look at the table below, check out how my SQL server 2008 R2 compares to other tools when backing up a 300GB database. It appears that when talking about the backup speed, SQL 2008 R2 compresses and performs backup in similar overall times as all three other tools. 3rd party tools maximum compression level takes twice longer. Backup file gain is not that impressive, except the highest compression levels but the price that you pay is very high cpu load and much longer time. Only SQL Safe by Idera was quite fast with it’s maximum compression level but most of the run time have used 95% cpu on the server. Note that I have used two types of destination storage, SATA 11 disks and FC 53 disks and, obviously, on faster storage have got my backup ready in half time. Looking at the above results, should we spend money, bother with another layer of complexity and software middle-man for the medium sized databases? I’m definitely not going to do so.  Very large database As a next phase of this benchmark, I have moved to a 6 terabyte database which was actually my main backup target. Note, how multiple files usage enables the SQL Server backup operation to use parallel I/O and remarkably increases it’s speed, especially when the backup device is heavily striped. SQL Server supports a maximum of 64 backup devices for a single backup operation but the most speed is gained when using one file per CPU, in the case above 8 files for a 2 Quad CPU server. The impact of additional files is minimal.  However, SQLsafe doesn’t show any speed improvement between 4 files and 8 files. Of course, with such huge databases every half percent of the compression transforms into the noticeable numbers. Saving almost 470GB of space may turn the backup tool into quite valuable purchase. Still, the backup speed and high CPU are the variables that should be taken into the consideration. As for us, the backup speed is more critical than the storage and we cannot allow a production server to sustain 95% cpu for such a long time. Bottomline, 3rd party backup tool developers, we are waiting for some breakthrough release. There are a few unanswered questions, like the restore speed comparison between different tools and the impact of multiple backup files on restore operation. Stay tuned for the next benchmarks.    Benchmark server: SQL Server 2008 R2 sp1 2 Quad CPU Database location: NetApp FC 15K Aggregate 53 discs Backup statements: No matter how good that UI is, we need to run the backup tasks from inside of SQL Server Agent to make sure they are covered by our monitoring systems. I have used extended stored procedures (command line execution also is an option, I haven’t noticed any impact on the backup performance). SQL backup LiteSpeed SQL Backup SQL safe backup database <DBNAME> to disk= '\\<networkpath>\par1.bak' , disk= '\\<networkpath>\par2.bak', disk= '\\<networkpath>\par3.bak' with format, compression EXECUTE master.dbo.xp_backup_database @database = N'<DBName>', @backupname= N'<DBName> full backup', @desc = N'Test', @compressionlevel=8, @filename= N'\\<networkpath>\par1.bak', @filename= N'\\<networkpath>\par2.bak', @filename= N'\\<networkpath>\par3.bak', @init = 1 EXECUTE master.dbo.sqlbackup '-SQL "BACKUP DATABASE <DBNAME> TO DISK= ''\\<networkpath>\par1.sqb'', DISK= ''\\<networkpath>\par2.sqb'', DISK= ''\\<networkpath>\par3.sqb'' WITH DISKRETRYINTERVAL = 30, DISKRETRYCOUNT = 10, COMPRESSION = 4, INIT"' EXECUTE master.dbo.xp_ss_backup @database = 'UCMSDB', @filename = '\\<networkpath>\par1.bak', @backuptype = 'Full', @compressionlevel = 4, @backupfile = '\\<networkpath>\par2.bak', @backupfile = '\\<networkpath>\par3.bak' If you still insist on using 3rd party tools for the backups in your production environment with maximum compression level, you will definitely need to consider limiting cpu usage which will increase the backup operation time even more: RedGate : use THREADPRIORITY option ( values 0 – 6 ) LiteSpeed : use  @throttle ( percentage, like 70%) SQL safe :  the only thing I have found was @Threads option.   Yours, Maria

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• CodePlex Daily Summary for Tuesday, December 11, 2012

  CodePlex Daily Summary for Tuesday, December 11, 2012Popular ReleasesDirectX Tool Kit: December 11, 2012: December 11, 2012 Ex versions of DDSTextureLoader and WICTextureLoader Removed use of ATL's CComPtr in favor of WRL's ComPtr for all platforms to support VS Express editions Updated VS 2010 project for official 'property sheet' integration for Windows 8.0 SDK Minor fix to CommonStates for Feature Level 9.1 Tweaked AlphaTestEffect.cpp to work around ARM NEON compiler codegen bug Added dxguid.lib as a default library for Debug builds to resolve GUID link issuesCleverBobCat: CleverBobCat 1.1.3: Fixed: - Cart code now works in vab, wheels retract correctly and no more anchors visible - No more exceptions on VAB Added: - ResourceTransfer beam now has a wide array of configurable options for beam material, size and colors - Added an optional offset to resource transfer, if specificed the "beam" will start from part center + the specified offsetSharpCompress - a fully native C# library for RAR, 7Zip, Zip, Tar, GZip, BZip2: SharpCompress 0.8.2: This release just contains some fixes that have been done since the last release. Plus, this is strong named as well. I apologize for the lack of updates but my free time is less these days.re-linq: 1.13.178.0: This is build 1.13.178.0 of re-linq. Find the complete release notes for the build here: Release NotesMedia Companion: MediaCompanion3.511b release: Two more bug fixes: - General Preferences were not getting restored - Fanart and poster image files were being locked, preventing changes to themVodigi Open Source Interactive Digital Signage: Vodigi Release 5.5: The following enhancements and fixes are included in Vodigi 5.5. Vodigi Administrator - Manage Music Files - Add Music Files to Image Slide Shows - Manage System Messages - Display System Messages to Users During Login - Ported to Visual Studio 2012 and MVC 4 - Added New Vodigi Administrator User Guide Vodigi Player - Improved Login/Schedule Startup Procedure - Startup Using Last Known Schedule when Disconnected on Startup - Improved Check for Schedule Changes - Now Every 15 Minutes - Pla...Secretary Tool: Secretary Tool v1.1.0: I'm still considering this version a beta version because, while it seems to work well for me, I haven't received any feedback and I certainly don't want anyone relying solely on this tool for calculations and such until its correct functioning is verified by someone. This version includes several bug fixes, including a rather major one with Emergency Contact Information not saving. Also, reporting is completed. There may be some tweaking to the reporting engine, but it is good enough to rel...VidCoder: 1.4.10 Beta: Added progress percent to the title bar/task bar icon. Added MPLS information to Blu-ray titles. Fixed the following display issues in Windows 8: Uncentered text in textbox controls Disabled controls not having gray text making them hard to identify as disabled Drop-down menus having hard-to distinguish white on light-blue text Added more logging to proxy disconnect issues and increased timeout on initial call to help prevent timeouts. Fixed encoding window showing the built-in pre...WPF Application Framework (WAF): WPF Application Framework (WAF) 2.5.0.400: Version 2.5.0.400 (Release): This release contains the source code of the WPF Application Framework (WAF) and the sample applications. Requirements .NET Framework 4.0 (The package contains a solution file for Visual Studio 2010) The unit test projects require Visual Studio 2010 Professional Changelog Legend: [B] Breaking change; [O] Marked member as obsolete Update the documentation. InfoMan: Write the documentation. Other Downloads Downloads OverviewHome Access Plus+: v8.5: v8.5.1211.1240 Fixed: changed to using the thumbnailPhoto attribute instead of jpegPhoto v8.5.1208.1500 This is a point release, for the other parts of HAP+ see the v8.3 release. Fixed: #me#me issue with the Edit Profile Link Updated: 8.5.1208 release Updated: Documentation with hidden booking system feature Added: Room Drop Down to the Booking System (no control panel interface), can be Resource Specific Fixed: Recursive AD Group Membership Lookup Fixed: User.IsInRole with recursive lookup...Http Explorer: httpExplorer-1.1: httpExplorer now has the ability to connect to http server via web proxies. The proxy may be explicitly specified by hostname or IP address. Or it may be specified via the Internet Options settings of Windows. You may also specify credentials to pass to the proxy if the proxy requires them. These credentials may be NTLM or basic authentication (clear text username and password).Bee OPOA Platform: Bee OPOA Demo V1.0.001: Initial version.Microsoft Ajax Minifier: Microsoft Ajax Minifier 4.78: Fix for issue #18924 - using -pretty option left in ///#DEBUG blocks. Fix for issue #18980 - bad += optimization caused bug in resulting code. Optimization has been removed pending further review.Dynamics Crm 2011 Solution Manager: Crm Solution Manager 1.0: First Version.Lava JS: Lava JS 1.0: Sourcemp3player-xslt-plugin: mp3player module 1.0: This is a mp3 player module that you can install on your umbraco project. It can display the list of the media and you can click the button to play or stop.STeaL : stealed functionarities from STL: STeaL 0.4.1(prelerease): + fill / fill-nMi-DevEnv: Development 0.5: Ran a new test scenario where I created a DC, then created a web server, blew it away, then re-created the web server. The purpose of the test was to see how the installers would handle information existing in AD, like the OU for CRM. This revealed yet another silly issue in retrieving details of existing OU's, where I had the syntax wrong. I should read exception details more closely :) Apologies also, I've just now started labelling the solution according to these "snapshots". Sorry for...Yahoo! UI Library: YUI Compressor for .Net: Version 2.2.0.0 - Epee: New : Web Optimization package! Cleaned up the nuget packages BugFix: minifying lots of files will now be faster because of a recent regression in some code. (We were instantiating something far too many times).DtPad - .NET Framework text editor: DtPad 2.9.0.40: http://dtpad.diariotraduttore.com/files/images/flag-eng.png English + A new built-in editor for the management of CSV files, including the edit of cells, deleting and adding new rows, replacement of delimiter character and much more (issue #1137) + The limit of rows allowed before the decommissioning of their side panel has been raised (new default: 1.000) (issue #1155, only partially solved) + Pressing CTRL+TAB now DtPad opens a screen that shows the list of opened tabs (issue #1143) + Note...New ProjectsAmazon S3 Upload with Uploadify: ASP.MVC upload file from client browser direct to Amazon S3Ameoto DEV: Bin for all of our software sources :DAutonomic Computing Library: This framework will simplify the development of Autonomic Computing Systems. BIUUITest: BIUUITestBotvaBot: This project should help tothe Botva.Ru gamers to automize their game proces. It is a set of libraries for simple sending of the HTTP requests with list of the main requests to the botva.ru web-site. Also project contains the clients forsimple using this request umulators.Cartellino: Scopo del progetto è la realizzazione di un software in grado di rilevare i dati dai rilevatori 3Tec (www.3tec.it) e stampare i cartellini presenza dei dipendenticmsforbeginner: in this project explain how to edit, create multiple webpages to a single website with less knowledge on html ,.net languagesContact Us Module: This is an Umbraco based module for feedback. You can upload the contact us module in the dashboard and then display those module anywhere in your site.CrmXpress Security Roles Helper For Microsoft Dynamics CRM 2011: CrmXpress Security Roles Helper is a tool/utility. It lets you compare the Security Roles for their differences at the privilege level with their scopes.DarkSky Helpdesk: DarkSky Helpdesk is an Orchard module that turns your Orchard application into a Helpdesk system.DataEntity: A Framework that help us to make persistences and materializations from any SQLServer DataBase Tables to Entity classes. Better performance with native ADO.NET.Edisfera DNN Training Task Module: This is a training project to familiarize with codeplex and dnn module creation.eyoung events description language: Eyoung is a event driven language. It can be used in many fields, such as intrusion action definition.FastBuild: Fast build VS2010 C++ project with the options OpenCV, QT, Boost and OpenGL.Find Changeset By Comment: This extension is used to find changesets that contain a specific phrase in a comment.Gatepass System: This application under development is my first application on codeplex. It is meant primarily as a learning tool while developing a Gatepass System. This GateHandle Template Library (HTL): Handle Template Library (HTL) is a C++ library for developing Windows applications and services. It provides a set of classes for files, threads, events, and more.iDoklad API: iDoklad API Demo je Open Source projekt spolecnosti Cígler Software. Ukázková aplikace demonstruje napojení na fakturacní službu iDokladIronBefunge: IronBefunge is an interpretor (written in .NET) for Befunge programs.Iterator Tasks: Iterator Tasks is a iterator-based coroutine class library.Javacc-Compile-N14: Javacc - compile - N14 is a students' compiler project and we use javacc to compiler XYZ-2 languageMessenger Game - Starter Kit: Kom godt i gang med at lave spil til Messenger med dette komplette Starter Kit. Indeholder et komplet netværksspil lavet med Messenger Activity API og Silverlight.MOBZcript: MOBZcript is a simple batch file editor for cmd scripts. It saves and runs your scripts as if you started them from a command line.NET.Library: The NET.Library will be available in different versions to run on the .Net 2, 3 and 4 frameworks and consists of various .Net programming utilities. proxificator: Proxificator is component for getting the appropriate proxyRetailManagement: abcStudentManage: testWebQQ Interface: A library that enable programmers to access QQ much easier via codeZytonic Screenshot: Upload Images From your Computer Harddrive or Screen With Ease!

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• Why unhandled exceptions are useful

  - by Simon Cooper

  It’s the bane of most programmers’ lives – an unhandled exception causes your application or webapp to crash, an ugly dialog gets displayed to the user, and they come complaining to you. Then, somehow, you need to figure out what went wrong. Hopefully, you’ve got a log file, or some other way of reporting unhandled exceptions (obligatory employer plug: SmartAssembly reports an application’s unhandled exceptions straight to you, along with the entire state of the stack and variables at that point). If not, you have to try and replicate it yourself, or do some psychic debugging to try and figure out what’s wrong. However, it’s good that the program crashed. Or, more precisely, it is correct behaviour. An unhandled exception in your application means that, somewhere in your code, there is an assumption that you made that is actually invalid. Coding assumptions Let me explain a bit more. Every method, every line of code you write, depends on implicit assumptions that you have made. Take this following simple method, that copies a collection to an array and includes an item if it isn’t in the collection already, using a supplied IEqualityComparer: public static T[] ToArrayWithItem( ICollection<T> coll, T obj, IEqualityComparer<T> comparer) { // check if the object is in collection already // using the supplied comparer foreach (var item in coll) { if (comparer.Equals(item, obj)) { // it's in the collection already // simply copy the collection to an array // and return it T[] array = new T[coll.Count]; coll.CopyTo(array, 0); return array; } } // not in the collection // copy coll to an array, and add obj to it // then return it T[] array = new T[coll.Count+1]; coll.CopyTo(array, 0); array[array.Length-1] = obj; return array; } What’s all the assumptions made by this fairly simple bit of code? coll is never null comparer is never null coll.CopyTo(array, 0) will copy all the items in the collection into the array, in the order defined for the collection, starting at the first item in the array. The enumerator for coll returns all the items in the collection, in the order defined for the collection comparer.Equals returns true if the items are equal (for whatever definition of ‘equal’ the comparer uses), false otherwise comparer.Equals, coll.CopyTo, and the coll enumerator will never throw an exception or hang for any possible input and any possible values of T coll will have less than 4 billion items in it (this is a built-in limit of the CLR) array won’t be more than 2GB, both on 32 and 64-bit systems, for any possible values of T (again, a limit of the CLR) There are no threads that will modify coll while this method is running and, more esoterically: The C# compiler will compile this code to IL according to the C# specification The CLR and JIT compiler will produce machine code to execute the IL on the user’s computer The computer will execute the machine code correctly That’s a lot of assumptions. Now, it could be that all these assumptions are valid for the situations this method is called. But if this does crash out with an exception, or crash later on, then that shows one of the assumptions has been invalidated somehow. An unhandled exception shows that your code is running in a situation which you did not anticipate, and there is something about how your code runs that you do not understand. Debugging the problem is the process of learning more about the new situation and how your code interacts with it. When you understand the problem, the solution is (usually) obvious. The solution may be a one-line fix, the rewrite of a method or class, or a large-scale refactoring of the codebase, but whatever it is, the fix for the crash will incorporate the new information you’ve gained about your own code, along with the modified assumptions. When code is running with an assumption or invariant it depended on broken, then the result is ‘undefined behaviour’. Anything can happen, up to and including formatting the entire disk or making the user’s computer sentient and start doing a good impression of Skynet. You might think that those can’t happen, but at Halting problem levels of generality, as soon as an assumption the code depended on is broken, the program can do anything. That is why it’s important to fail-fast and stop the program as soon as an invariant is broken, to minimise the damage that is done. What does this mean in practice? To start with, document and check your assumptions. As with most things, there is a level of judgement required. How you check and document your assumptions depends on how the code is used (that’s some more assumptions you’ve made), how likely it is a method will be passed invalid arguments or called in an invalid state, how likely it is the assumptions will be broken, how expensive it is to check the assumptions, and how bad things are likely to get if the assumptions are broken. Now, some assumptions you can assume unless proven otherwise. You can safely assume the C# compiler, CLR, and computer all run the method correctly, unless you have evidence of a compiler, CLR or processor bug. You can also assume that interface implementations work the way you expect them to; implementing an interface is more than simply declaring methods with certain signatures in your type. The behaviour of those methods, and how they work, is part of the interface contract as well. For example, for members of a public API, it is very important to document your assumptions and check your state before running the bulk of the method, throwing ArgumentException, ArgumentNullException, InvalidOperationException, or another exception type as appropriate if the input or state is wrong. For internal and private methods, it is less important. If a private method expects collection items in a certain order, then you don’t necessarily need to explicitly check it in code, but you can add comments or documentation specifying what state you expect the collection to be in at a certain point. That way, anyone debugging your code can immediately see what’s wrong if this does ever become an issue. You can also use DEBUG preprocessor blocks and Debug.Assert to document and check your assumptions without incurring a performance hit in release builds. On my coding soapbox… A few pet peeves of mine around assumptions. Firstly, catch-all try blocks: try { ... } catch { } A catch-all hides exceptions generated by broken assumptions, and lets the program carry on in an unknown state. Later, an exception is likely to be generated due to further broken assumptions due to the unknown state, causing difficulties when debugging as the catch-all has hidden the original problem. It’s much better to let the program crash straight away, so you know where the problem is. You should only use a catch-all if you are sure that any exception generated in the try block is safe to ignore. That’s a pretty big ask! Secondly, using as when you should be casting. Doing this: (obj as IFoo).Method(); or this: IFoo foo = obj as IFoo; ... foo.Method(); when you should be doing this: ((IFoo)obj).Method(); or this: IFoo foo = (IFoo)obj; ... foo.Method(); There’s an assumption here that obj will always implement IFoo. If it doesn’t, then by using as instead of a cast you’ve turned an obvious InvalidCastException at the point of the cast that will probably tell you what type obj actually is, into a non-obvious NullReferenceException at some later point that gives you no information at all. If you believe obj is always an IFoo, then say so in code! Let it fail-fast if not, then it’s far easier to figure out what’s wrong. Thirdly, document your assumptions. If an algorithm depends on a non-trivial relationship between several objects or variables, then say so. A single-line comment will do. Don’t leave it up to whoever’s debugging your code after you to figure it out. Conclusion It’s better to crash out and fail-fast when an assumption is broken. If it doesn’t, then there’s likely to be further crashes along the way that hide the original problem. Or, even worse, your program will be running in an undefined state, where anything can happen. Unhandled exceptions aren’t good per-se, but they give you some very useful information about your code that you didn’t know before. And that can only be a good thing.

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• Nginx no longer servers uwsgi application behind HAProxy - Looks for static file instead

  - by Ralph

  We implemented our web application using web2py. It consists of several modules offering a REST API at various resources (e.g. /dids, /replicas, ...). The API is used by clients implementing requests.py. My problem is that our web app works fine if it's behind HAProxy and hosted by Apache using mod_wsgi. It also works fine if the clients interact with nginx directly. It doesn't work though when using HAProxy in front of nginx. My guess is that HAProxy somehow modifies the request and thus nginx behaves differently i.e. looking for a static file instead of calling the WSGI container. Unfortunately I can't figure out what's exactly going (wr)on(g). Here are the relevant config sections of these three component's config files. At least I guess they are interesting. If you miss anything, please let me know. 1) haproxy.conf frontend app-lb bind loadbalancer:443 ssl crt /etc/grid-security/hostcertkey.pem default_backend nginx-servers mode http backend nginx-servers balance leastconn option forwardfor server nginx-01 nginx-server-int-01.domain.com:80 check 2) nginx.conf: sendfile off; #tcp_nopush on; keepalive_timeout 65; include /etc/nginx/conf.d/*.conf; server { server_name nginx-server-int-01.domain.com; root /path/to/app/; location / { uwsgi_pass unix:///tmp/app.sock; include uwsgi_params; uwsgi_read_timeout 600; # Requests can run for a serious long time } 3) uwsgi.ini [uwsgi] chdir = /path/to/app/ chmod-socket = 777 no-default-app = True socket = /tmp/app.sock manage-script-name = True mount = /dids=did.py mount = /replicas=replica.py callable = application Now when I let my clients go against nginx-server-int-01.domain.com everything is fine. In the access.log of nginx lines like these are appearing: 128.142.XXX.XX0 - - [23/Aug/2014:01:29:20 +0200] "POST /dids/attachments HTTP/1.1" 201 17 "-" "python-requests/2.3.0 CPython/2.6.6 Linux/2.6.32-358.23.2.el6.x86_64" "-" 128.142.XXX.XX0 - - [23/Aug/2014:01:29:20 +0200] "POST /dids/attachments HTTP/1.1" 201 17 "-" "python-requests/2.3.0 CPython/2.6.6 Linux/2.6.32-358.23.2.el6.x86_64" "-" 128.142.XXX.XX0 - - [23/Aug/2014:01:29:20 +0200] "POST /dids/user.ogueta/cnt_mc12_8TeV.16304.stream_name_too_long.other.notype.004202218365415e990b9997ea859f20.user/dids HTTP/1.1" 201 17 "-" "python-requests/2.3.0 CPython/2.6.6 Linux/2.6.32-358.23.2.el6.x86_64" "-" 128.142.XXX.XX0 - - [23/Aug/2014:01:29:20 +0200] "POST /replicas/list HTTP/1.1" 200 5282 "-" "python-requests/2.3.0 CPython/2.6.6 Linux/2.6.32-358.23.2.el6.x86_64" "-" 128.142.XXX.XX0 - - [23/Aug/2014:01:29:20 +0200] "POST /replicas/list HTTP/1.1" 200 5094 "-" "python-requests/2.3.0 CPython/2.6.6 Linux/2.6.32-358.23.2.el6.x86_64" "-" 128.142.XXX.XX0 - - [23/Aug/2014:01:29:20 +0200] "POST /replicas/list HTTP/1.1" 200 528 "-" "python-requests/2.3.0 CPython/2.6.6 Linux/2.6.32-358.23.2.el6.x86_64" "-" 128.142.XXX.XX0 - - [23/Aug/2014:01:29:21 +0200] "GET /dids/mc13_14TeV/dids/search?project=mc13_14TeV&stream_name=%2Adummy&type=dataset&datatype=NTUP_SMDYMUMU HTTP/1.1" 401 73 "-" "python-requests/2.3.0 CPython/2.6.6 Linux/2.6.32-358.23.2.el6.x86_64" "-" 128.142.XXX.XX0 - - [23/Aug/2014:01:29:21 +0200] "POST /replicas/list HTTP/1.1" 200 713 "-" "python-requests/2.3.0 CPython/2.6.6 Linux/2.6.32-358.23.2.el6.x86_64" "-" 128.142.XXX.XX0 - - [23/Aug/2014:01:29:21 +0200] "POST /dids/attachments HTTP/1.1" 201 17 "-" "python-requests/2.3.0 CPython/2.6.6 Linux/2.6.32-358.23.2.el6.x86_64" "-" But when I switch the clients to go against HAProxy (loadbalancer.domain.com:443), the error.log of nginx shows lines like these: 2014/08/23 01:26:01 [error] 1705#0: *21231 open() "/usr/share/nginx/html/dids/attachments" failed (2: No such file or directory), client: 128.142.XXX.XX1, server: localhost, request: "POST /dids/attachments HTTP/1.1", host: "loadbalancer.domain.com" 2014/08/23 01:26:02 [error] 1705#0: *21232 open() "/usr/share/nginx/html/replicas/list" failed (2: No such file or directory), client: 128.142.XXX.XX1, server: localhost, request: "POST /replicas/list HTTP/1.1", host: "loadbalancer.domain.com" 2014/08/23 01:26:02 [error] 1705#0: *21233 open() "/usr/share/nginx/html/dids/attachments" failed (2: No such file or directory), client: 128.142.XXX.XX1, server: localhost, request: "POST /dids/attachments HTTP/1.1", host: "loadbalancer.domain.com" 2014/08/23 01:26:02 [error] 1705#0: *21234 open() "/usr/share/nginx/html/replicas/list" failed (2: No such file or directory), client: 128.142.XXX.XX1, server: localhost, request: "POST /replicas/list HTTP/1.1", host: "loadbalancer.domain.com" 2014/08/23 01:26:02 [error] 1705#0: *21235 open() "/usr/share/nginx/html/dids/attachments" failed (2: No such file or directory), client: 128.142.XXX.XXX, server: localhost, request: "POST /dids/attachments HTTP/1.1", host: "loadbalancer" 2014/08/23 01:26:02 [error] 1705#0: *21238 open() "/usr/share/nginx/html/replicas/list" failed (2: No such file or directory), client: 128.142.XXX.XXX, server: localhost, request: "POST /replicas/list HTTP/1.1", host: "loadbalancer.domain.com" 2014/08/23 01:26:02 [error] 1705#0: *21239 open() "/usr/share/nginx/html/dids/attachments" failed (2: No such file or directory), client: 128.142.XXX.XXX, server: localhost, request: "POST /dids/attachments HTTP/1.1", host: "loadbalancer.domain.com" 2014/08/23 01:26:02 [error] 1705#0: *21242 open() "/usr/share/nginx/html/replicas/list" failed (2: No such file or directory), client: 128.142.XXX.XXX, server: localhost, request: "POST /replicas/list HTTP/1.1", host: "loadbalancer.domain.com" 2014/08/23 01:26:02 [error] 1705#0: *21244 open() "/usr/share/nginx/html/dids/attachments" failed (2: No such file or directory), client: 128.142.XXX.XXX, server: localhost, request: "POST /dids/attachments HTTP/1.1", host: "loadbalancer.domain.com" As you can see, that request looks the same, only the client IP changed, from the client's host to the one from loadbalancer.domain.com. But due to what ever reasons ngxin seems to assume that it is a static file to be served which eventually results in the file not found message. I searched the web for multiple hours already, but without much luck so far. Any help is very much appreciated. Cheers, Ralph

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• Conducting Effective Web Meetings

  - by BuckWoody

  There are several forms of corporate communication. From immediate, rich communications like phones and IM messaging to historical transactions like e-mail, there are a lot of ways to get information to one or more people. From time to time, it's even useful to have a meeting. (This is where a witty picture of a guy sleeping in a meeting goes. I won't bother actually putting one here; you're already envisioning it in your mind) Most meetings are pointless, and a complete waste of time. This is the fault, completely and solely, of the organizer. It's because he or she hasn't thought things through enough to think about alternate forms of information passing. Here's the criteria for a good meeting - whether in-person or over the web: 100% of the content of a meeting should require the participation of 100% of the attendees for 100% of the time It doesn't get any simpler than that. If it doesn't meet that criteria, then don't invite that person to that meeting. If you're just conveying information and no one has the need for immediate interaction with that information (like telling you something that modifies the message), then send an e-mail. If you're a manager, and you need to get status from lots of people, pick up the phone.If you need a quick answer, use IM. I once had a high-level manager that called frequent meetings. His real need was status updates on various processes, so 50 of us would sit in a room while he asked each one of us questions. He believed this larger meeting helped us "cross pollinate ideas". In fact, it was a complete waste of time for most everyone, except in the one or two moments that they interacted with him. So I wrote some code for a Palm Pilot (which was a kind of SmartPhone but with no phone and no real graphics, but this was in the days when we had just discovered fire and the wheel, although the order of those things is still in debate) that took an average of the salaries of the people in the room (I guessed at it) and ran a timer which multiplied the number of people against the salaries. I left that running in plain sight for him, and when he asked about it, I explained how much the meetings were really costing the company. We had far fewer meetings after. Meetings are now web-enabled. I believe that's largely a good thing, since it saves on travel time and allows more people to participate, but I think the rule above still holds. And in fact, there are some other rules that you should follow to have a great meeting - and fewer of them. Be Clear About the Goal This is important in any meeting, but all of us have probably gotten an invite with a web link and an ambiguous title. Then you get to the meeting, and it's a 500-level deep-dive on something everyone expects you to know. This is unfair to the "expert" and to the participants. I always tell people that invite me to a meeting that I will be as detailed as I can - but the more detail they can tell me about the questions, the more detailed I can be in my responses. Granted, there are times when you don't know what you don't know, but the more you can say about the topic the better. There's another point here - and it's that you should have a clearly defined "win" for the meeting. When the meeting is over, and everyone goes back to work, what were you expecting them to do with the information? Have that clearly defined in your head, and in the meeting invite. Understand the Technology There are several web-meeting clients out there. I use them all, since I meet with clients all over the world. They all work differently - so I take a few moments and read up on the different clients and find out how I can use the tools properly. I do this with the technology I use for everything else, and it's important to understand it if the meeting is to be a success. If you're running the meeting, know the tools. I don't care if you like the tools or not, learn them anyway. Don't waste everyone else's time just because you're too bitter/snarky/lazy to spend a few minutes reading. Check your phone or mic. Check your video size. Install (and learn to use)  ZoomIT (http://technet.microsoft.com/en-us/sysinternals/bb897434.aspx). Format your slides or screen or output correctly. Learn to use the voting features of the meeting software, and especially it's whiteboard features. Figure out how multiple monitors work. Try a quick meeting with someone to test all this. Do this *before* you invite lots of other people to your meeting.   Use a WebCam I'm not a pretty man. I have a face fit for radio. But after attending a meeting with clients where one Microsoft person used a webcam and another did not, I'm convinced that people pay more attention when a face is involved. There are tons of studies around this, or you can take my word for it, but toss a shirt on over those pajamas and turn the webcam on. Set Up Early Whether you're attending or leading the meeting, don't wait to sign on to the meeting at the time when it starts. I can almost plan that a 10:00 meeting will actually start at 10:10 because the participants/leader is just now installing the web client for the meeting at 10:00. Sign on early, go on mute, and then wait for everyone to arrive. Mute When Not Talking No one wants to hear your screaming offspring / yappy dog / other cubicle conversations / car wind noise (are you driving in a desert storm or something?) while the person leading the meeting is trying to talk. I use the Lync software from Microsoft for my meetings, and I mute everyone by default, and then tell them to un-mute to talk to the group. Share Collateral If you have a PowerPoint deck, mail it out in case you have a tech failure. If you have a document, share it as an attachment to the meeting. Don't make people ask you for the information - that's why you're there to begin with. Even better, send it out early. "But", you say, "then no one will come to the meeting if they have the deck first!" Uhm, then don't have a meeting. Send out the deck and a quick e-mail and let everyone get on with their productive day. Set Actions At the Meeting A meeting should have some sort of outcome (see point one). That means there are actions to take, a follow up, or some deliverable. Otherwise, it's an e-mail. At the meeting, decide who will do what, when things are needed, and so on. And avoid, if at all possible, setting up another meeting, unless absolutely necessary. So there you have it. Whether it's on-premises or on the web, meetings are a necessary evil, and should be treated that way. Like politicians, you should have as few of them as are necessary to keep the roads paved and public libraries open.

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• Exception Handling And Other Contentious Political Topics

  - by Justin Jones

  So about three years ago, around the time of my last blog post, I promised a friend I would write this post. Keeping promises is a good thing, and this is my first step towards easing back into regular blogging. I fully expect him to return from Pennsylvania to buy me a beer over this. However, it’s been an… ahem… eventful three years or so, and blogging, unfortunately, got pushed to the back burner on my priority list, along with a few other career minded activities. Now that the personal drama of the past three years is more or less resolved, it’s time to put a few things back on the front burner. What I consider to be proper exception handling practices is relatively well known these days. There are plenty of blog posts out there already on this topic which more or less echo my opinions on this topic. I’ll try to include a few links at the bottom of the post. Several years ago I had an argument with a co-worker who posited that exceptions should be caught at every level and logged. This might seem like sanity on the surface, but the resulting error log looked something like this: Error: System.SomeException Followed by small stack trace. Error: System.SomeException Followed by slightly bigger stack trace. Error: System.SomeException Followed by slightly bigger stack trace. Error: System.SomeException Followed by slightly bigger stack trace. Error: System.SomeException Followed by slightly bigger stack trace. Error: System.SomeException Followed by slightly bigger stack trace. Error: System.SomeException Followed by slightly bigger stack trace. Error: System.SomeException Followed by slightly bigger stack trace.   These were all the same exception. The problem with this approach is that the error log, if you run any kind of analytics on in, becomes skewed depending on how far up the stack trace your exception was thrown. To mitigate this problem, we came up with the concept of the “PreLoggedException”. Basically, we would log the exception at the very top level and subsequently throw the exception back up the stack encapsulated in this pre-logged type, which our logging system knew to ignore. Now the error log looked like this: Error: System.SomeException Followed by small stack trace. Much cleaner, right? Well, there’s still a problem. When your exception happens in production and you go about trying to figure out what happened, you’ve lost more or less all context for where and how this exception was thrown, because all you really know is what method it was thrown in, but really nothing about who was calling the method or why. What gives you this clue is the entire stack trace, which we’re losing here. I believe that was further mitigated by having the logging system pull a system stack trace and add it to the log entry, but what you’re actually getting is the stack for how you got to the logging code. You’re still losing context about the actual error. Not to mention you’re executing a whole slew of catch blocks which are sloooooooowwwww……… In other words, we started with a bad idea and kept band-aiding it until it didn’t suck quite so bad. When I argued for not catching exceptions at every level but rather catching them following a certain set of rules, my co-worker warned me “do yourself a favor, never express that view in any future interviews.” I suppose this is my ultimate dismissal of that advice, but I’m not too worried. My approach for exception handling follows three basic rules: Only catch an exception if 1. You can do something about it. 2. You can add useful information to it. 3. You’re at an application boundary. Here’s what that means: 1. Only catch an exception if you can do something about it. We’ll start with a trivial example of a login system that uses a file. Please, never actually do this in production code, it’s just concocted example. So if our code goes to open a file and the file isn’t there, we get a FileNotFound exception. If the calling code doesn’t know what to do with this, it should bubble up. However, if we know how to create the file from scratch we can create the file and continue on our merry way. When you run into situations like this though, What should really run through your head is “How can I avoid handling an exception at all?” In this case, it’s a trivial matter to simply check for the existence of the file before trying to open it. If we detect that the file isn’t there, we can accomplish the same thing without having to handle in in a catch block. 2. Only catch an exception if you can do something about it. Continuing with the poorly thought out file based login system we contrived in part 1, if the code calls a Login(…) method and the FileNotFound exception is thrown higher up the stack, the code that calls Login must account for a FileNotFound exception. This is kind of counterintuitive because the calling code should not need to know the internals of the Login method, and the data file is an implementation detail. What makes more sense, assuming that we didn’t implement any of the good advice from step 1, is for Login to catch the FileNotFound exception and wrap it in a new exception. For argument’s sake we’ll say LoginSystemFailureException. (Sorry, couldn’t think of anything better at the moment.) This gives us two stack traces, preserving the original stack trace in the inner exception, and also is much more informative to the calling code. 3. Only catch an exception if you’re at an application boundary. At some point we have to catch all the exceptions, even the ones we don’t know what to do with. WinForms, ASP.Net, and most other UI technologies have some kind of built in mechanism for catching unhandled exceptions without fatally terminating the application. It’s still a good idea to somehow gracefully exit the application in this case if possible though, because you can no longer be sure what state your application is in, but nothing annoys a user more than an application just exploding. These unhandled exceptions need to be logged, and this is a good place to catch them. Ideally you never want this option to be exercised, but code as though it will be. When you log these exceptions, give them a “Fatal” status (e.g. Log4Net) and make sure these bugs get handled in your next release. That’s it in a nutshell. If you do it right each exception will only get logged once and with the largest stack trace possible which will make those 2am emergency severity 1 debugging sessions much shorter and less frustrating. Here’s a few people who also have interesting things to say on this topic:  http://blogs.msdn.com/b/ericlippert/archive/2008/09/10/vexing-exceptions.aspx http://www.codeproject.com/Articles/9538/Exception-Handling-Best-Practices-in-NET I know there’s more but I can’t find them at the moment.

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• CodePlex Daily Summary for Monday, July 22, 2013

  CodePlex Daily Summary for Monday, July 22, 2013Popular ReleasesAndroidCopyAndPaste: Capood: Erstes Release für Evaluation --> Changeset 26675fastJSON: v2.0.17: 2.0.17 - added serialization of static fields and properties - added dynamic object support and testKartris Ecommerce ASP.NET Shopping Cart: Kartris v2.5002: This is the release version of Kartris with the responsive interface based on Zurb's Foundation framework. It will work on any screen size, down to and including mobile devices such as the iphone. We've also fixed issues with Apple iOS products being treated by ASP.NET as 'downscale' devices, which broke some functionality in Kartris. This release also includes native Bitcoin support (no third party services required - it communicates directly with the standard Bitcoin client via a JSON API)...VG-Ripper & PG-Ripper: PG-Ripper 1.4.15: changes NEW: Added Support for "ImgChili.net" links NEW: Added Support for "ImgBabes.com" linksAcDown?????: AcDown????? v4.4.3: ??●AcDown??????????、??、??、???????。????，????，?????????????????????????。???????????Acfun、????(Bilibili)、??、??、YouTube、??、???、??????、SF????、????????????。 ●??????AcPlay?????，??????、????????????????。 ● AcDown???????C#??，????.NET Framework 2.0??。?????"Acfun?????"。 ??v4.4.3 ?? ??Bilibili????????????? ???????????? ????32??64? Windows XP/Vista/7/8 ???? 32??64? ???Linux ????(1)????????Windows XP???，????????.NET Framework 2.0???(x86)，?????"?????????"??? (2)???????????Linux???，????????Mono?? ??2.10?...Magick.NET: Magick.NET 6.8.6.601: Magick.NET linked with ImageMagick 6.8.6.6. These zip files are also available as a NuGet package: https://nuget.org/profiles/dlemstra/MISAO: Ver. 5.33: Latest app and add-insC# Intellisense for Notepad++: Initial release: Members auto-complete Integration with native Notepad++ Auto-Completion Auto "open bracket" for methods Right-arrow to accept suggestions51Degrees.mobi - Mobile Device Detection and Redirection: 2.1.19.4: One Click Install from NuGet This release introduces the 51Degrees.mobi IIS Vary Header Fix. When Compression and Caching is used in IIS, the Vary header is overwritten, making intelligent caching with dynamic content impossible. Find out more about installing the Vary Header fix. Changes to Version 2.1.19.4Handlers now have a ‘Count’ property. This is an integer value that shows how many devices in the dataset that use that handler. Provider.cs -> GetDeviceInfoByID to address a problem w...SalarDbCodeGenerator: SalarDbCodeGenerator v2.1.2013.0719: Version 2.1.2013.0719 2013/7/19 Pattern Changes: * DapperContext pattern is added. * All patterns are updated to work with one-to-one relations. Changes: * One-to-one relation is supported. * Minor bug fixes..NET Code Migrator for Dynamics CRM: v1.0.12: Combined the main macros, generated macros from a sample organization, and the CreateVisualStudioMacros utility into a single package.DARF: Dynamic Application Runtime Framework: DARF.Demo: This demo is DARF.IDE application plus a sample file (calculator.xda) which describes a very simple calculator. All you need to do is to unzip the package, run DARF.IDE.exe and load calculator.xda then press F5 or select 'Execute' from 'Code' menu to see the execution of the application. The calculator.xda file is fully commented so you can inspect the file and get a feeling of the way DARF works. This sample application makes use of some pre-written blocks (namely button, textbox and ...) ...Player Framework by Microsoft: Player Framework for Windows and WP (v1.3 beta 2): Includes all changes in v1.3 beta 1 Additional support for Windows 8.1 Preview New API (JS): addTextTrack New API (JS): msKeys New API (JS): msPlayToPreferredSourceUri New API (JS): msSetMediaKeys New API (JS): onmsneedkey New API (Xaml): SetMediaStreamSource method New API (Xaml): Stretch property New API (Xaml): StretchChanged event New API (Xaml): AreTransportControlsEnabled property New API (Xaml): IsFullWindow property New API (Xaml): PlayToPreferredSourceUri proper...CodeGen Code Generator: CodeGen 4.2.11: Changes in this release include: Added several new alternate forms of the <FIELD_SELWND> token to provide template developers better control over the case of field selection window names. Also added a new token <FIELD_SELWND_ORIGINAL> to preserve the case of selection window names in the same way that <FIELD_SELWND> used to. Enhanced UI Toolkit window script selection window processing (-ws) so that selection window names are no longer case sensitive (they aren't in UI Toolkit). Also the -w...Outlook 2013 Add-In: Multiple Calendars: As per popular request, this new version includes: - Support for multiple calendars. This can be enabled in the configuration by choosing which ones to show/hide appointments from. In some cases (public folders) it may time out and crash, and so far it only supports "My Calendars", so not shared ones yet. Also they're currently shown in the same font/color so there are no confusions with color categories, but please drop me a line on any suggestions you'd like to see implemented. - Added fri...Circuit Diagram: Circuit Diagram 2.0 Beta 2: New in this release: Show grid in editor Cut/copy/paste support Bug fixesOrchard Project: Orchard 1.7 RC: Planning releasedTerminals: Version 3.1 - Release: Changes since version 3.0:15992 Unified usage of icons in user interface Added context menu in Organize favorites grid Fixed:34219 34210 34223 33981 34209 Install notes:No changes in database (use database from release 3.0) No upgrade of configuration, passwords, credentials or favorites See also upgrade notes for release 3.0Media Companion: Media Companion MC3.573b: XBMC Link - Let MC update your XBMC Library Fixes in place, Enjoy the XBMC Link function Well, Phil's been busy in the background, and come up with a Great new feature for Media Companion. Currently only implemented for movies. Once we're happy that's working with no issues, we'll extend the functionality to include TV shows. All the help for this is build into the application. Go to General Preferences - XBMC Link for details. Help us make it better* Currently only tested on local and ...Wsus Package Publisher: Release v1.2.1307.15: Fix a bug where WPP crash if 'ShowPendingUpdates' is start with wrong credentials. Fix a bug where WPP crash if ArrivalDateAfter and ArrivalDateBefore is equal in the ComputerView. Add a filter in the ComputerView. (Thanks to NorbertFe for this feature request) Add an option, when right-clicking on a computer, you can ask for display the current logon user of the remote computer. Add an option in settings to choose if WPP ping remote computers using IPv4, IPv6 or IPv6 and, if fail, IP...New ProjectsAssociativy Tag Nodes: Lightweight Associativy nodes that behave somewhat like tags.CESQLite2013: SQLite for Windows Embedded Compact 2013: A project to provide SQLite.dll for x86 Windows Embedded Compact 2013cmsserver: ????，HTTP??DDRMenu Extension for Ventrian Simple Gallery: The aim of this project is to include inside the DDRMenu all the gallery availables as subitem of the page they are onto.Devanagari Keyboard: Windows Marathi, Devanagari Keyboard Software by Nitin SawantFastMessages. MSG.Exe Alternative. Easily send messages to desktop: Easily send messages to desktop. A simple command (FastMessage.exe) acts as an alternative to MSG.EXE into scripts. Destinations can be domain users or groups.GameTools: ??????，?????????Memory Teaser Game: It is a game written in C sharp .NET version 4.5.RegEdit for Windows Embedded Compact (Windows CE): Registry editor for Windows Embedded Compact (Windows CE).Scripter: Scripter is designed to handle client side activities consumed by a websiteStartingwithServiceBusCSharp: this project is a very basic introduction to start developing using Windows Azure Service Bus using Brokered, queue messaging.Team 2 Collaboration: Whaddup!VM Project Generator Release: Generator Abrevieri Viorel MadaWatcher Orchard module: Orchard module for watching content items and geting notified on modifications.Workout Tracker: Simple workout tracker.zendigh php framework: zendigh is open source php framework to create high traffic websites.

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• elffile: ELF Specific File Identification Utility

  - by user9154181

  Solaris 11 has a new standard user level command, /usr/bin/elffile. elffile is a variant of the file utility that is focused exclusively on linker related files: ELF objects, archives, and runtime linker configuration files. All other files are simply identified as "non-ELF". The primary advantage of elffile over the existing file utility is in the area of archives — elffile examines the archive members and can produce a summary of the contents, or per-member details. The impetus to add elffile to Solaris came from the effort to extend the format of Solaris archives so that they could grow beyond their previous 32-bit file limits. That work introduced a new archive symbol table format. Now that there was more than one possible format, I thought it would be useful if the file utility could identify which format a given archive is using, leading me to extend the file utility: % cc -c ~/hello.c % ar r foo.a hello.o % file foo.a foo.a: current ar archive, 32-bit symbol table % ar r -S foo.a hello.o % file foo.a foo.a: current ar archive, 64-bit symbol table In turn, this caused me to think about all the things that I would like the file utility to be able to tell me about an archive. In particular, I'd like to be able to know what's inside without having to unpack it. The end result of that train of thought was elffile. Much of the discussion in this article is adapted from the PSARC case I filed for elffile in December 2010: PSARC 2010/432 elffile Why file Is No Good For Archives And Yet Should Not Be Fixed The standard /usr/bin/file utility is not very useful when applied to archives. When identifying an archive, a user typically wants to know 2 things: Is this an archive? Presupposing that the archive contains objects, which is by far the most common use for archives, what platform are the objects for? Are they for sparc or x86? 32 or 64-bit? Some confusing combination from varying platforms? The file utility provides a quick answer to question (1), as it identifies all archives as "current ar archive". It does nothing to answer the more interesting question (2). To answer that question, requires a multi-step process: Extract all archive members Use the file utility on the extracted files, examine the output for each file in turn, and compare the results to generate a suitable summary description. Remove the extracted files It should be easier and more efficient to answer such an obvious question. It would be reasonable to extend the file utility to examine archive contents in place and produce a description. However, there are several reasons why I decided not to do so: The correct design for this feature within the file utility would have file examine each archive member in turn, applying its full abilities to each member. This would be elegant, but also represents a rather dramatic redesign and re-implementation of file. Archives nearly always contain nothing but ELF objects for a single platform, so such generality in the file utility would be of little practical benefit. It is best to avoid adding new options to standard utilities for which other implementations of interest exist. In the case of the file utility, one concern is that we might add an option which later appears in the GNU version of file with a different and incompatible meaning. Indeed, there have been discussions about replacing the Solaris file with the GNU version in the past. This may or may not be desirable, and may or may not ever happen. Either way, I don't want to preclude it. Examining archive members is an O(n) operation, and can be relatively slow with large archives. The file utility is supposed to be a very fast operation. I decided that extending file in this way is overkill, and that an investment in the file utility for better archive support would not be worth the cost. A solution that is more narrowly focused on ELF and other linker related files is really all that we need. The necessary code for doing this already exists within libelf. All that is missing is a small user-level wrapper to make that functionality available at the command line. In that vein, I considered adding an option for this to the elfdump utility. I examined elfdump carefully, and even wrote a prototype implementation. The added code is small and simple, but the conceptual fit with the rest of elfdump is poor. The result complicates elfdump syntax and documentation, definite signs that this functionality does not belong there. And so, I added this functionality as a new user level command. The elffile Command The syntax for this new command is elffile [-s basic | detail | summary] filename... Please see the elffile(1) manpage for additional details. To demonstrate how output from elffile looks, I will use the following files: FileDescription configA runtime linker configuration file produced with crle dwarf.oAn ELF object /etc/passwdA text file mixed.aArchive containing a mixture of ELF and non-ELF members mixed_elf.aArchive containing ELF objects for different machines not_elf.aArchive containing no ELF objects same_elf.aArchive containing a collection of ELF objects for the same machine. This is the most common type of archive. The file utility identifies these files as follows: % file config dwarf.o /etc/passwd mixed.a mixed_elf.a not_elf.a same_elf.a config: Runtime Linking Configuration 64-bit MSB SPARCV9 dwarf.o: ELF 64-bit LSB relocatable AMD64 Version 1 /etc/passwd: ascii text mixed.a: current ar archive, 32-bit symbol table mixed_elf.a: current ar archive, 32-bit symbol table not_elf.a: current ar archive same_elf.a: current ar archive, 32-bit symbol table By default, elffile uses its "summary" output style. This output differs from the output from the file utility in 2 significant ways: Files that are not an ELF object, archive, or runtime linker configuration file are identified as "non-ELF", whereas the file utility attempts further identification for such files. When applied to an archive, the elffile output includes a description of the archive's contents, without requiring member extraction or other additional steps. Applying elffile to the above files: % elffile config dwarf.o /etc/passwd mixed.a mixed_elf.a not_elf.a same_elf.a config: Runtime Linking Configuration 64-bit MSB SPARCV9 dwarf.o: ELF 64-bit LSB relocatable AMD64 Version 1 /etc/passwd: non-ELF mixed.a: current ar archive, 32-bit symbol table, mixed ELF and non-ELF content mixed_elf.a: current ar archive, 32-bit symbol table, mixed ELF content not_elf.a: current ar archive, non-ELF content same_elf.a: current ar archive, 32-bit symbol table, ELF 64-bit LSB relocatable AMD64 Version 1 The output for same_elf.a is of particular interest: The vast majority of archives contain only ELF objects for a single platform, and in this case, the default output from elffile answers both of the questions about archives posed at the beginning of this discussion, in a single efficient step. This makes elffile considerably more useful than file, within the realm of linker-related files. elffile can produce output in two other styles, "basic", and "detail". The basic style produces output that is the same as that from 'file', for linker-related files. The detail style produces per-member identification of archive contents. This can be useful when the archive contents are not homogeneous ELF object, and more information is desired than the summary output provides: % elffile -s detail mixed.a mixed.a: current ar archive, 32-bit symbol table mixed.a(dwarf.o): ELF 32-bit LSB relocatable 80386 Version 1 mixed.a(main.c): non-ELF content mixed.a(main.o): ELF 64-bit LSB relocatable AMD64 Version 1 [SSE]

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• IPTables masquerading with one NIC

  - by Tuinslak

  Hi, I am running an OpenVPN server with only one NIC. This is my current layout: public.ip > Cisco firewall > lan.ip > OpenVPN server lan.ip = 192.168.22.70 The Cisco firewall forwards the requests to the oVPN server, thus so far everything works and clients are able to connect. However, all clients connected should be able to access 3 networks: lan1: 192.168.200.0 (vpn lan) > tun0 lan2: 192.168.110.0 (office lan) > eth1 (gw 192.168.22.1) lan3: 192.168.22.0 (server lan) > eth1 (broadcast network) So tun0 is mapped to eth1. Iptables output: # iptables-save # Generated by iptables-save v1.4.2 on Wed Feb 16 14:14:20 2011 *filter :INPUT ACCEPT [327:26098] :FORWARD DROP [305:31700] :OUTPUT ACCEPT [291:27378] -A INPUT -i lo -j ACCEPT -A INPUT -i tun0 -j ACCEPT -A INPUT -i ! tun0 -p udp -m udp --dport 67 -j REJECT --reject-with icmp-port-unreachable -A INPUT -i ! tun0 -p udp -m udp --dport 53 -j REJECT --reject-with icmp-port-unreachable -A FORWARD -d 192.168.200.0/24 -i tun0 -j DROP -A FORWARD -s 192.168.200.0/24 -i tun0 -j ACCEPT -A FORWARD -d 192.168.200.0/24 -i eth1 -j ACCEPT COMMIT # Completed on Wed Feb 16 14:14:20 2011 # Generated by iptables-save v1.4.2 on Wed Feb 16 14:14:20 2011 *nat :PREROUTING ACCEPT [302:26000] :POSTROUTING ACCEPT [3:377] :OUTPUT ACCEPT [49:3885] -A POSTROUTING -o eth1 -j MASQUERADE COMMIT # Completed on Wed Feb 16 14:14:20 2011 Yet, clients are unable to ping any ip (including 192.168.200.1, which is the oVPN's IP) When the machine was directly connected to the internet, with 2 NICs, it was quite simply solved with masquerading and adding static routes in the oVPN client's config. However, as masquerading won't accept virtual interfaces (eth0:0, etc) I am unable to get masquerading to work again (and I'm not even sure whether I need virtual interfaces). Thanks. Edit: OpenVPN server: # ifconfig eth1 Link encap:Ethernet HWaddr ba:e6:64:ec:57:ac inet addr:192.168.22.70 Bcast:192.168.22.255 Mask:255.255.255.0 inet6 addr: fe80::b8e6:64ff:feec:57ac/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:6857 errors:0 dropped:0 overruns:0 frame:0 TX packets:4044 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:584046 (570.3 KiB) TX bytes:473691 (462.5 KiB) Interrupt:14 lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:334 errors:0 dropped:0 overruns:0 frame:0 TX packets:334 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:33773 (32.9 KiB) TX bytes:33773 (32.9 KiB) tun0 Link encap:UNSPEC HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00 inet addr:192.168.200.1 P-t-P:192.168.200.2 Mask:255.255.255.255 UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:100 RX bytes:0 (0.0 B) TX bytes:0 (0.0 B) ifconfig on a client: # ifconfig eth0 Link encap:Ethernet HWaddr 00:22:64:71:11:56 inet addr:192.168.110.94 Bcast:192.168.110.255 Mask:255.255.255.0 inet6 addr: fe80::222:64ff:fe71:1156/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:3466 errors:0 dropped:0 overruns:0 frame:0 TX packets:1838 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:997924 (974.5 KiB) TX bytes:332406 (324.6 KiB) Interrupt:17 lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:37847 errors:0 dropped:0 overruns:0 frame:0 TX packets:37847 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:2922444 (2.7 MiB) TX bytes:2922444 (2.7 MiB) tun0 Link encap:UNSPEC HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00 inet addr:192.168.200.30 P-t-P:192.168.200.29 Mask:255.255.255.255 UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:689 errors:0 dropped:18 overruns:0 carrier:0 collisions:0 txqueuelen:100 RX bytes:0 (0.0 B) TX bytes:468778 (457.7 KiB) wlan0 Link encap:Ethernet HWaddr 00:16:ea:db:ae:86 UP BROADCAST MULTICAST MTU:1500 Metric:1 RX packets:704699 errors:0 dropped:0 overruns:0 frame:0 TX packets:730176 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:520385963 (496.2 MiB) TX bytes:225210422 (214.7 MiB) static routes line at the end of the client's config (I've been playing around with the 192.168.200.0 -- (un)commenting to see if anything changes): route 192.168.200.0 255.255.255.0 route 192.168.110.0 255.255.255.0 route 192.168.22.0 255.255.255.0 route on a vpn client: # route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 192.168.200.29 0.0.0.0 255.255.255.255 UH 0 0 0 tun0 192.168.22.0 192.168.200.29 255.255.255.0 UG 0 0 0 tun0 192.168.200.0 192.168.200.29 255.255.255.0 UG 0 0 0 tun0 192.168.110.0 192.168.200.29 255.255.255.0 UG 0 0 0 tun0 192.168.110.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0 0.0.0.0 192.168.110.1 0.0.0.0 UG 0 0 0 eth0 edit: Weirdly enough, if I set push "redirect-gateway def1" in the server config, (and thus routes all traffic through VPN, which is not what I want), it seems to work.

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• CodePlex Daily Summary for Tuesday, July 30, 2013

  CodePlex Daily Summary for Tuesday, July 30, 2013Popular ReleasesnopCommerce. Open source shopping cart (ASP.NET MVC): nopCommerce 3.10: Highlight features & improvements: • Performance optimization. • New more user-friendly product/product-variant logic. Now we'll have only products (simple and grouped). • Bundle products support added. • Allow a store owner to associate product image for product variant attribute values. To see the full list of fixes and changes please visit the release notes page (http://www.nopCommerce.com/releasenotes.aspx).Small Tools: Helpers 1.01: Fix params count issue Fix STAThread issue Add support for exe.config filesExtJS based ASP.NET Controls: FineUI v3.3.1: ??FineUI ?? ExtJS ??? ASP.NET ???。 FineUI??? ?? No JavaScript，No CSS，No UpdatePanel，No ViewState，No WebServices ???????。 ?????? IE 7.0、Firefox 3.6、Chrome 3.0、Opera 10.5、Safari 3.0+ ???? Apache License v2.0 ?：ExtJS ?? GPL v3 ?????(http://www.sencha.com/license)。 ???? ??：http://fineui.com/bbs/ ??：http://fineui.com/demo/ ??：http://fineui.com/doc/ ??：http://fineui.codeplex.com/ FineUI ???? ExtJS ????????，???? ExtJS ?，???????????ExtJS?： 1. ????? FineUI ? ExtJS ?：http://fineui.com/bbs/fo...AutoNLayered - Domain Oriented N-Layered .NET 4.5: AutoNLayered v1.0.5: - Fix Dtos. Abstract collections replaced by concrete (correct serialization WCF). - OrderBy in navigation properties. - Unit Test with Fakes. - Map of entities/dto moved to application services. - Libraries updated. Warning using Fakes: http://connect.microsoft.com/VisualStudio/feedback/details/782031/visual-studio-2012-add-fakes-assembly-does-not-add-all-needed-referencesPath Copy Copy: 11.1: Minor release with two new features: Submenu's contextual menu item now has an icon next to it Added reference to JavaScript regular expression format in Settings application Since this release does not have any glaring bug fixes, it is more of an optional update for existing users. It depends on whether you want to be able to spot the Path Copy Copy submenu more easily. I recommend you install it to see if the icon makes sense. As always, please don't hesitate to leave feedback via Discus...CMake Tools for Visual Studio: CMake Tools for Visual Studio 1.0 RC3: This is the third release candidate of CMake Tools for Visual Studio 1.0, which contains the following bug fixes: Opening a CMake file from Windows Explorer while Visual Studio is already open will no start a new instance of Visual Studio. Typing a symbol while the IntelliSense list box is visible and the text typed so far does not match any item in the list will dismiss the list box and insert the symbol typed.R.NET: R.NET 1.5: The major changes in v1.5 are: Initialize method must be called before using R. Settings should be passed to the method. EagerEvaluate method renamed to Evaluate (use Defer method when you want old version of Evaluate).Media Companion: Media Companion MC3.574b: Some good bug fixes been going on with the new XBMC-Link function. Thanks to all who were able to do testing and gave feedback. New:* Added some adhoc extra General movie filters, one of which is Plot = Outline (see fixes above). To see the filters, add the following line to your config.xml: <ShowExtraMovieFilters>True</ShowExtraMovieFilters>. The others are: Imdb in folder name, Imdb in not folder name & Imdb not in folder name & year mismatch. * Movie - display <tag> list on browser tab ...OfflineBrowser: Preview Release with Search: I've added search to this release.VG-Ripper & PG-Ripper: VG-Ripper 2.9.46: changes FIXED LoginMath.NET Numerics: Math.NET Numerics v2.6.0: What's New in Math.NET Numerics 2.6 - Announcement, Explanations and Sample Code. New: Linear Curve Fitting Linear least-squares fitting (regression) to lines, polynomials and linear combinations of arbitrary functions. Multi-dimensional fitting. Also works well in F# with the F# extensions. New: Root Finding Brent's method. ~Candy Chiu, Alexander Täschner Bisection method. ~Scott Stephens, Alexander Täschner Broyden's method, for multi-dimensional functions. ~Alexander Täschner ...AJAX Control Toolkit: July 2013 Release: AJAX Control Toolkit Release Notes - July 2013 Release Version 7.0725July 2013 release of the AJAX Control Toolkit. AJAX Control Toolkit .NET 4.5 – AJAX Control Toolkit for .NET 4.5 and sample site (Recommended). AJAX Control Toolkit .NET 4 – AJAX Control Toolkit for .NET 4 and sample site (Recommended). AJAX Control Toolkit .NET 3.5 – AJAX Control Toolkit for .NET 3.5 and sample site (Recommended). Notes: - Instructions for using the AJAX Control Toolkit with ASP.NET 4.5 can be found at...MJP's DirectX 11 Samples: Specular Antialiasing Sample: Sample code to complement my presentation that's part of the Physically Based Shading in Theory and Practice course at SIGGRAPH 2013, entitled "Crafting a Next-Gen Material Pipeline for The Order: 1886". Demonstrates various methods of preventing aliasing from specular BRDF's when using high-frequency normal maps. The zip file contains source code as well as a pre-compiled x64 binary.EXCEL??、??、????????：DataPie（??MSSQL 2008、ORACLE、ACCESS 2007）: DataPieV3.6.1: ????csv????，???sql??，??csv????Qibla Compass for Windows Phone: Qibla Compass for Windows Phone: This release is in open beta version. You can always download and provide your feedback. Since it was just developed to give users an idea of Qibla Direction and its mapping therefore you might not see major releases in future.Event Scavenger: Version 5: I've decided to do a full (recommended) release of version 5. I've been running it myself for months and did not have any issues with it yet. This release just contains the installs. The web site's documentation has not been updated yet and reflects the previous version details. If you have an issue with this version then you can happily switch back to 4.x. Version 5 can run side-by-side with earlier versions (service) as it has a new service and database.wpadk: WPadk_WP8???: ???：V1.1 ??wp???????????????wp8???????StockSharp: StockSharp 4.1.16: ?????? ????????? - http://stocksharp.com/forum/yaf_postsm28239_S--API-4-1.aspx#post28239GeoTransformer: GeoTransformer 4.5: Extensions can now be installed and uninstalled from the application. The extensions update the same way as the application - silently and automatically. Added ability to search for caches by pressing CTRL+F in the table views. (Thanks to JanisU for implementing this request) Added ability to remove edited customizations for multiple caches at once (use SHIFT or CTRL to select multiple lines in the table). A new experimental version for Windows 8 RT (on ARM processor) is also made availa...Kartris E-commerce: Kartris v2.5003: This fixes an issue where search engines appear to identify as IE and so trigger the noIE page if there is not a non-responsive skin specified.New ProjectsBus Booking System: Bus Booking systemC#??????: ????C#??????????????。Cotizav 2.0: Este proyecto es para el soporte de Cotizaciones.DeferredShading: deferred shading rendererIVR Junction: IVR Junction connects an Interactive Voice Response (IVR) system to cloud services such as YouTube, Facebook and other social media.Mac Address Changer: It's a quite and easy tool to change your mac addressmotokraft user control: user control for motokraftSingle Reference JavaScript Pattern: This is very simple pattern. In here you need to only refer one script in a page. I'm sure it is saving your development time as well as maintenance timeSocial_Life_Time: This is social network that people can communicate with each otherThe Ironic Text Based MMORPG: Modern MMORPGs have become highly interactive, complex systems of skills, stats, and action combat. This game introduces a new level of text based immersion!Timeline Year Control: Timeline Year Control An ASP.Net year indicator timeline control.winrtsock: winsock façade for Windows Runtime for porting bsd socket code to Windows RuntimeZker: No summary?????: C#?????

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• Why do we (really) program to interfaces?

  - by Kyle Burns

  One of the earliest lessons I was taught in Enterprise development was "always program against an interface".  This was back in the VB6 days and I quickly learned that no code would be allowed to move to the QA server unless my business objects and data access objects each are defined as an interface and have a matching implementation class.  Why?  "It's more reusable" was one answer.  "It doesn't tie you to a specific implementation" a slightly more knowing answer.  And let's not forget the discussion ending "it's a standard".  The problem with these responses was that senior people didn't really understand the reason we were doing the things we were doing and because of that, we were entirely unable to realize the intent behind the practice - we simply used interfaces and had a bunch of extra code to maintain to show for it. It wasn't until a few years later that I finally heard the term "Inversion of Control".  Simply put, "Inversion of Control" takes the creation of objects that used to be within the control (and therefore a responsibility of) of your component and moves it to some outside force.  For example, consider the following code which follows the old "always program against an interface" rule in the manner of many corporate development shops: 1: ICatalog catalog = new Catalog(); 2: Category[] categories = catalog.GetCategories(); In this example, I met the requirement of the rule by declaring the variable as ICatalog, but I didn't hit "it doesn't tie you to a specific implementation" because I explicitly created an instance of the concrete Catalog object.  If I want to test the functionality of the code I just wrote I have to have an environment in which Catalog can be created along with any of the resources upon which it depends (e.g. configuration files, database connections, etc) in order to test my functionality.  That's a lot of setup work and one of the things that I think ultimately discourages real buy-in of unit testing in many development shops. So how do I test my code without needing Catalog to work?  A very primitive approach I've seen is to change the line the instantiates catalog to read: 1: ICatalog catalog = new FakeCatalog();   once the test is run and passes, the code is switched back to the real thing.  This obviously poses a huge risk for introducing test code into production and in my opinion is worse than just keeping the dependency and its associated setup work.  Another popular approach is to make use of Factory methods which use an object whose "job" is to know how to obtain a valid instance of the object.  Using this approach, the code may look something like this: 1: ICatalog catalog = CatalogFactory.GetCatalog();   The code inside the factory is responsible for deciding "what kind" of catalog is needed.  This is a far better approach than the previous one, but it does make projects grow considerably because now in addition to the interface, the real implementation, and the fake implementation(s) for testing you have added a minimum of one factory (or at least a factory method) for each of your interfaces.  Once again, developers say "that's too complicated and has me writing a bunch of useless code" and quietly slip back into just creating a new Catalog and chalking any test failures up to "it will probably work on the server". This is where software intended specifically to facilitate Inversion of Control comes into play.  There are many libraries that take on the Inversion of Control responsibilities in .Net and most of them have many pros and cons.  From this point forward I'll discuss concepts from the standpoint of the Unity framework produced by Microsoft's Patterns and Practices team.  I'm primarily focusing on this library because it questions about it inspired this posting. At Unity's core and that of most any IoC framework is a catalog or registry of components.  This registry can be configured either through code or using the application's configuration file and in the most simple terms says "interface X maps to concrete implementation Y".  It can get much more complicated, but I want to keep things at the "what does it do" level instead of "how does it do it".  The object that exposes most of the Unity functionality is the UnityContainer.  This object exposes methods to configure the catalog as well as the Resolve<T> method which is used to obtain an instance of the type represented by T.  When using the Resolve<T> method, Unity does not necessarily have to just "new up" the requested object, but also can track dependencies of that object and ensure that the entire dependency chain is satisfied. There are three basic ways that I have seen Unity used within projects.  Those are through classes directly using the Unity container, classes requiring injection of dependencies, and classes making use of the Service Locator pattern. The first usage of Unity is when classes are aware of the Unity container and directly call its Resolve method whenever they need the services advertised by an interface.  The up side of this approach is that IoC is utilized, but the down side is that every class has to be aware that Unity is being used and tied directly to that implementation. Many developers don't like the idea of as close a tie to specific IoC implementation as is represented by using Unity within all of your classes and for the most part I agree that this isn't a good idea.  As an alternative, classes can be designed for Dependency Injection.  Dependency Injection is where a force outside the class itself manipulates the object to provide implementations of the interfaces that the class needs to interact with the outside world.  This is typically done either through constructor injection where the object has a constructor that accepts an instance of each interface it requires or through property setters accepting the service providers.  When using dependency, I lean toward the use of constructor injection because I view the constructor as being a much better way to "discover" what is required for the instance to be ready for use.  During resolution, Unity looks for an injection constructor and will attempt to resolve instances of each interface required by the constructor, throwing an exception of unable to meet the advertised needs of the class.  The up side of this approach is that the needs of the class are very clearly advertised and the class is unaware of which IoC container (if any) is being used.  The down side of this approach is that you're required to maintain the objects passed to the constructor as instance variables throughout the life of your object and that objects which coordinate with many external services require a lot of additional constructor arguments (this gets ugly and may indicate a need for refactoring). The final way that I've seen and used Unity is to make use of the ServiceLocator pattern, of which the Patterns and Practices team has also provided a Unity-compatible implementation.  When using the ServiceLocator, your class calls ServiceLocator.Retrieve in places where it would have called Resolve on the Unity container.  Like using Unity directly, it does tie you directly to the ServiceLocator implementation and makes your code aware that dependency injection is taking place, but it does have the up side of giving you the freedom to swap out the underlying IoC container if necessary.  I'm not hugely concerned with hiding IoC entirely from the class (I view this as a "nice to have"), so the single biggest problem that I see with the ServiceLocator approach is that it provides no way to proactively advertise needs in the way that constructor injection does, allowing more opportunity for difficult to track runtime errors. This blog entry has not been intended in any way to be a definitive work on IoC, but rather as something to spur thought about why we program to interfaces and some ways to reach the intended value of the practice instead of having it just complicate your code.  I hope that it helps somebody begin or continue a journey away from being a "Cargo Cult Programmer".

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• Per-pixel displacement mapping GLSL

  - by Chris

  Im trying to implement a per-pixel displacement shader in GLSL. I read through several papers and "tutorials" I found and ended up with trying to implement the approach NVIDIA used in their Cascade Demo (http://www.slideshare.net/icastano/cascades-demo-secrets) starting at Slide 82. At the moment I am completly stuck with following problem: When I am far away the displacement seems to work. But as more I move closer to my surface, the texture gets bent in x-axis and somehow it looks like there is a little bent in general in one direction. EDIT: I added a video: click I added some screen to illustrate the problem: Well I tried lots of things already and I am starting to get a bit frustrated as my ideas run out. I added my full VS and FS code: VS: #version 400 layout(location = 0) in vec3 IN_VS_Position; layout(location = 1) in vec3 IN_VS_Normal; layout(location = 2) in vec2 IN_VS_Texcoord; layout(location = 3) in vec3 IN_VS_Tangent; layout(location = 4) in vec3 IN_VS_BiTangent; uniform vec3 uLightPos; uniform vec3 uCameraDirection; uniform mat4 uViewProjection; uniform mat4 uModel; uniform mat4 uView; uniform mat3 uNormalMatrix; out vec2 IN_FS_Texcoord; out vec3 IN_FS_CameraDir_Tangent; out vec3 IN_FS_LightDir_Tangent; void main( void ) { IN_FS_Texcoord = IN_VS_Texcoord; vec4 posObject = uModel * vec4(IN_VS_Position, 1.0); vec3 normalObject = (uModel * vec4(IN_VS_Normal, 0.0)).xyz; vec3 tangentObject = (uModel * vec4(IN_VS_Tangent, 0.0)).xyz; //vec3 binormalObject = (uModel * vec4(IN_VS_BiTangent, 0.0)).xyz; vec3 binormalObject = normalize(cross(tangentObject, normalObject)); // uCameraDirection is the camera position, just bad named vec3 fvViewDirection = normalize( uCameraDirection - posObject.xyz); vec3 fvLightDirection = normalize( uLightPos.xyz - posObject.xyz ); IN_FS_CameraDir_Tangent.x = dot( tangentObject, fvViewDirection ); IN_FS_CameraDir_Tangent.y = dot( binormalObject, fvViewDirection ); IN_FS_CameraDir_Tangent.z = dot( normalObject, fvViewDirection ); IN_FS_LightDir_Tangent.x = dot( tangentObject, fvLightDirection ); IN_FS_LightDir_Tangent.y = dot( binormalObject, fvLightDirection ); IN_FS_LightDir_Tangent.z = dot( normalObject, fvLightDirection ); gl_Position = (uViewProjection*uModel) * vec4(IN_VS_Position, 1.0); } The VS just builds the TBN matrix, from incoming normal, tangent and binormal in world space. Calculates the light and eye direction in worldspace. And finally transforms the light and eye direction into tangent space. FS: #version 400 // uniforms uniform Light { vec4 fvDiffuse; vec4 fvAmbient; vec4 fvSpecular; }; uniform Material { vec4 diffuse; vec4 ambient; vec4 specular; vec4 emissive; float fSpecularPower; float shininessStrength; }; uniform sampler2D colorSampler; uniform sampler2D normalMapSampler; uniform sampler2D heightMapSampler; in vec2 IN_FS_Texcoord; in vec3 IN_FS_CameraDir_Tangent; in vec3 IN_FS_LightDir_Tangent; out vec4 color; vec2 TraceRay(in float height, in vec2 coords, in vec3 dir, in float mipmap){ vec2 NewCoords = coords; vec2 dUV = - dir.xy * height * 0.08; float SearchHeight = 1.0; float prev_hits = 0.0; float hit_h = 0.0; for(int i=0;i<10;i++){ SearchHeight -= 0.1; NewCoords += dUV; float CurrentHeight = textureLod(heightMapSampler,NewCoords.xy, mipmap).r; float first_hit = clamp((CurrentHeight - SearchHeight - prev_hits) * 499999.0,0.0,1.0); hit_h += first_hit * SearchHeight; prev_hits += first_hit; } NewCoords = coords + dUV * (1.0-hit_h) * 10.0f - dUV; vec2 Temp = NewCoords; SearchHeight = hit_h+0.1; float Start = SearchHeight; dUV *= 0.2; prev_hits = 0.0; hit_h = 0.0; for(int i=0;i<5;i++){ SearchHeight -= 0.02; NewCoords += dUV; float CurrentHeight = textureLod(heightMapSampler,NewCoords.xy, mipmap).r; float first_hit = clamp((CurrentHeight - SearchHeight - prev_hits) * 499999.0,0.0,1.0); hit_h += first_hit * SearchHeight; prev_hits += first_hit; } NewCoords = Temp + dUV * (Start - hit_h) * 50.0f; return NewCoords; } void main( void ) { vec3 fvLightDirection = normalize( IN_FS_LightDir_Tangent ); vec3 fvViewDirection = normalize( IN_FS_CameraDir_Tangent ); float mipmap = 0; vec2 NewCoord = TraceRay(0.1,IN_FS_Texcoord,fvViewDirection,mipmap); //vec2 ddx = dFdx(NewCoord); //vec2 ddy = dFdy(NewCoord); vec3 BumpMapNormal = textureLod(normalMapSampler, NewCoord.xy, mipmap).xyz; BumpMapNormal = normalize(2.0 * BumpMapNormal - vec3(1.0, 1.0, 1.0)); vec3 fvNormal = BumpMapNormal; float fNDotL = dot( fvNormal, fvLightDirection ); vec3 fvReflection = normalize( ( ( 2.0 * fvNormal ) * fNDotL ) - fvLightDirection ); float fRDotV = max( 0.0, dot( fvReflection, fvViewDirection ) ); vec4 fvBaseColor = textureLod( colorSampler, NewCoord.xy,mipmap); vec4 fvTotalAmbient = fvAmbient * fvBaseColor; vec4 fvTotalDiffuse = fvDiffuse * fNDotL * fvBaseColor; vec4 fvTotalSpecular = fvSpecular * ( pow( fRDotV, fSpecularPower ) ); color = ( fvTotalAmbient + (fvTotalDiffuse + fvTotalSpecular) ); } The FS implements the displacement technique in TraceRay method, while always using mipmap level 0. Most of the code is from NVIDIA sample and another paper I found on the web, so I guess there cannot be much wrong in here. At the end it uses the modified UV coords for getting the displaced normal from the normal map and the color from the color map. I looking forward for some ideas. Thanks in advance! Edit: Here is the code loading the heightmap: glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, mWidth, mHeight, 0, GL_RGBA, GL_UNSIGNED_BYTE, mImageData); glGenerateMipmap(GL_TEXTURE_2D); //glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR_MIPMAP_LINEAR); //glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR); //glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT); //glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT); Maybe something wrong in here?

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• Solving Big Problems with Oracle R Enterprise, Part I

  - by dbayard

  Abstract: This blog post will show how we used Oracle R Enterprise to tackle a customer’s big calculation problem across a big data set. Overview: Databases are great for managing large amounts of data in a central place with rigorous enterprise-level controls.  R is great for doing advanced computations.  Sometimes you need to do advanced computations on large amounts of data, subject to rigorous enterprise-level concerns.  This blog post shows how Oracle R Enterprise enables R plus the Oracle Database enabled us to do some pretty sophisticated calculations across 1 million accounts (each with many detailed records) in minutes. The problem: A financial services customer of mine has a need to calculate the historical internal rate of return (IRR) for its customers’ portfolios.  This information is needed for customer statements and the online web application.  In the past, they had solved this with a home-grown application that pulled trade and account data out of their data warehouse and ran the calculations.  But this home-grown application was not able to do this fast enough, plus it was a challenge for them to write and maintain the code that did the IRR calculation. IRR – a problem that R is good at solving: Internal Rate of Return is an interesting calculation in that in most real-world scenarios it is impractical to calculate exactly.  Rather, IRR is a calculation where approximation techniques need to be used.  In this blog post, we will discuss calculating the “money weighted rate of return” but in the actual customer proof of concept we used R to calculate both money weighted rate of returns and time weighted rate of returns.  You can learn more about the money weighted rate of returns here: http://www.wikinvest.com/wiki/Money-weighted_return First Steps- Calculating IRR in R We will start with calculating the IRR in standalone/desktop R.  In our second post, we will show how to take this desktop R function, deploy it to an Oracle Database, and make it work at real-world scale.  The first step we did was to get some sample data.  For a historical IRR calculation, you have a balances and cash flows.  In our case, the customer provided us with several accounts worth of sample data in Microsoft Excel.      The above figure shows part of the spreadsheet of sample data.  The data provides balances and cash flows for a sample account (BMV=beginning market value. FLOW=cash flow in/out of account. EMV=ending market value). Once we had the sample spreadsheet, the next step we did was to read the Excel data into R.  This is something that R does well.  R offers multiple ways to work with spreadsheet data.  For instance, one could save the spreadsheet as a .csv file.  In our case, the customer provided a spreadsheet file containing multiple sheets where each sheet provided data for a different sample account.  To handle this easily, we took advantage of the RODBC package which allowed us to read the Excel data sheet-by-sheet without having to create individual .csv files.  We wrote ourselves a little helper function called getsheet() around the RODBC package.  Then we loaded all of the sample accounts into a data.frame called SimpleMWRRData. Writing the IRR function At this point, it was time to write the money weighted rate of return (MWRR) function itself.  The definition of MWRR is easily found on the internet or if you are old school you can look in an investment performance text book.  In the customer proof, we based our calculations off the ones defined in the The Handbook of Investment Performance: A User’s Guide by David Spaulding since this is the reference book used by the customer.  (One of the nice things we found during the course of this proof-of-concept is that by using R to write our IRR functions we could easily incorporate the specific variations and business rules of the customer into the calculation.) The key thing with calculating IRR is the need to solve a complex equation with a numerical approximation technique.  For IRR, you need to find the value of the rate of return (r) that sets the Net Present Value of all the flows in and out of the account to zero.  With R, we solve this by defining our NPV function: where bmv is the beginning market value, cf is a vector of cash flows, t is a vector of time (relative to the beginning), emv is the ending market value, and tend is the ending time. Since solving for r is a one-dimensional optimization problem, we decided to take advantage of R’s optimize method (http://stat.ethz.ch/R-manual/R-patched/library/stats/html/optimize.html). The optimize method can be used to find a minimum or maximum; to find the value of r where our npv function is closest to zero, we wrapped our npv function inside the abs function and asked optimize to find the minimum.  Here is an example of using optimize: where low and high are scalars that indicate the range to search for an answer.   To test this out, we need to set values for bmv, cf, t, emv, tend, low, and high.  We will set low and high to some reasonable defaults. For example, this account had a negative 2.2% money weighted rate of return. Enhancing and Packaging the IRR function With numerical approximation methods like optimize, sometimes you will not be able to find an answer with your initial set of inputs.  To account for this, our approach was to first try to find an answer for r within a narrow range, then if we did not find an answer, try calling optimize() again with a broader range.  See the R help page on optimize()  for more details about the search range and its algorithm. At this point, we can now write a simplified version of our MWRR function.  (Our real-world version is  more sophisticated in that it calculates rate of returns for 5 different time periods [since inception, last quarter, year-to-date, last year, year before last year] in a single invocation.  In our actual customer proof, we also defined time-weighted rate of return calculations.  The beauty of R is that it was very easy to add these enhancements and additional calculations to our IRR package.)To simplify code deployment, we then created a new package of our IRR functions and sample data.  For this blog post, we only need to include our SimpleMWRR function and our SimpleMWRRData sample data.  We created the shell of the package by calling: To turn this package skeleton into something usable, at a minimum you need to edit the SimpleMWRR.Rd and SimpleMWRRData.Rd files in the \man subdirectory.  In those files, you need to at least provide a value for the “title” section. Once that is done, you can change directory to the IRR directory and type at the command-line: The myIRR package for this blog post (which has both SimpleMWRR source and SimpleMWRRData sample data) is downloadable from here: myIRR package Testing the myIRR package Here is an example of testing our IRR function once it was converted to an installable package: Calculating IRR for All the Accounts So far, we have shown how to calculate IRR for a single account.  The real-world issue is how do you calculate IRR for all of the accounts?This is the kind of situation where we can leverage the “Split-Apply-Combine” approach (see http://www.cscs.umich.edu/~crshalizi/weblog/815.html).  Given that our sample data can fit in memory, one easy approach is to use R’s “by” function.  (Other approaches to Split-Apply-Combine such as plyr can also be used.  See http://4dpiecharts.com/2011/12/16/a-quick-primer-on-split-apply-combine-problems/). Here is an example showing the use of “by” to calculate the money weighted rate of return for each account in our sample data set.  Recap and Next Steps At this point, you’ve seen the power of R being used to calculate IRR.  There were several good things: R could easily work with the spreadsheets of sample data we were given R’s optimize() function provided a nice way to solve for IRR- it was both fast and allowed us to avoid having to code our own iterative approximation algorithm R was a convenient language to express the customer-specific variations, business-rules, and exceptions that often occur in real-world calculations- these could be easily added to our IRR functions The Split-Apply-Combine technique can be used to perform calculations of IRR for multiple accounts at once. However, there are several challenges yet to be conquered at this point in our story: The actual data that needs to be used lives in a database, not in a spreadsheet The actual data is much, much bigger- too big to fit into the normal R memory space and too big to want to move across the network The overall process needs to run fast- much faster than a single processor The actual data needs to be kept secured- another reason to not want to move it from the database and across the network And the process of calculating the IRR needs to be integrated together with other database ETL activities, so that IRR’s can be calculated as part of the data warehouse refresh processes In our next blog post in this series, we will show you how Oracle R Enterprise solved these challenges.

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• Applications: The Mathematics of Movement, Part 2

  - by TechTwaddle

  In part 1 of this series we saw how we can make the marble move towards the click point, with a fixed speed. In this post we’ll see, first, how to get rid of Atan2(), sine() and cosine() in our calculations, and, second, reducing the speed of the marble as it approaches the destination, so it looks like the marble is easing into it’s final position. As I mentioned in one of the previous posts, this is achieved by making the speed of the marble a function of the distance between the marble and the destination point. Getting rid of Atan2(), sine() and cosine() Ok, to be fair we are not exactly getting rid of these trigonometric functions, rather, replacing one form with another. So instead of writing sin(?), we write y/length. You see the point. So instead of using the trig functions as below, double x = destX - marble1.x; double y = destY - marble1.y; //distance between destination and current position, before updating marble position distanceSqrd = x * x + y * y; double angle = Math.Atan2(y, x); //Cos and Sin give us the unit vector, 6 is the value we use to magnify the unit vector along the same direction incrX = speed * Math.Cos(angle); incrY = speed * Math.Sin(angle); marble1.x += incrX; marble1.y += incrY; we use the following, double x = destX - marble1.x; double y = destY - marble1.y; //distance between destination and marble (before updating marble position) lengthSqrd = x * x + y * y; length = Math.Sqrt(lengthSqrd); //unit vector along the same direction as vector(x, y) unitX = x / length; unitY = y / length; //update marble position incrX = speed * unitX; incrY = speed * unitY; marble1.x += incrX; marble1.y += incrY; so we replaced cos(?) with x/length and sin(?) with y/length. The result is the same.   Adding oomph to the way it moves In the last post we had the speed of the marble fixed at 6, double speed = 6; to make the marble decelerate as it moves, we have to keep updating the speed of the marble in every frame such that the speed is calculated as a function of the length. So we may have, speed = length/12; ‘length’ keeps decreasing as the marble moves and so does speed. The Form1_MouseUp() function remains the same as before, here is the UpdatePosition() method, private void UpdatePosition() {     double incrX = 0, incrY = 0;     double lengthSqrd = 0, length = 0, lengthSqrdNew = 0;     double unitX = 0, unitY = 0;     double speed = 0;     double x = destX - marble1.x;     double y = destY - marble1.y;     //distance between destination and marble (before updating marble position)     lengthSqrd = x * x + y * y;     length = Math.Sqrt(lengthSqrd);     //unit vector along the same direction as vector(x, y)     unitX = x / length;     unitY = y / length;     //speed as a function of length     speed = length / 12;     //update marble position     incrX = speed * unitX;     incrY = speed * unitY;     marble1.x += incrX;     marble1.y += incrY;     //check for bounds     if ((int)marble1.x < MinX + marbleWidth / 2)     {         marble1.x = MinX + marbleWidth / 2;     }     else if ((int)marble1.x > (MaxX - marbleWidth / 2))     {         marble1.x = MaxX - marbleWidth / 2;     }     if ((int)marble1.y < MinY + marbleHeight / 2)     {         marble1.y = MinY + marbleHeight / 2;     }     else if ((int)marble1.y > (MaxY - marbleHeight / 2))     {         marble1.y = MaxY - marbleHeight / 2;     }     //distance between destination and marble (after updating marble position)     x = destX - (marble1.x);     y = destY - (marble1.y);     lengthSqrdNew = x * x + y * y;     /*      * End Condition:      * 1. If there is not much difference between lengthSqrd and lengthSqrdNew      * 2. If the marble has moved more than or equal to a distance of totLenToTravel (see Form1_MouseUp)      */     x = startPosX - marble1.x;     y = startPosY - marble1.y;     double totLenTraveledSqrd = x * x + y * y;     if ((int)totLenTraveledSqrd >= (int)totLenToTravelSqrd)     {         System.Console.WriteLine("Stopping because Total Len has been traveled");         timer1.Enabled = false;     }     else if (Math.Abs((int)lengthSqrd - (int)lengthSqrdNew) < 4)     {         System.Console.WriteLine("Stopping because no change in Old and New");         timer1.Enabled = false;     } } A point to note here is that, in this implementation, the marble never stops because it travelled a distance of totLenToTravelSqrd (first if condition). This happens because speed is a function of the length. During the final few frames length becomes very small and so does speed; and so the amount by which the marble shifts is quite small, and the second if condition always hits true first. I’ll end this series with a third post. In part 3 we will cover two things, one, when the user clicks, the marble keeps moving in that direction, rebounding off the screen edges and keeps moving forever. Two, when the user clicks on the screen, the marble moves towards it, with it’s speed reducing by every frame. It doesn’t come to a halt when the destination point is reached, instead, it continues to move, rebounds off the screen edges and slowly comes to halt. The amount of time that the marble keeps moving depends on how far the user clicks from the marble. I had mentioned this second situation here. Finally, here’s a video of this program running,

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• We've completed the first iteration

  - by CliveT

  There are a lot of features in C# that are implemented by the compiler and not by the underlying platform. One such feature is a lambda expression. Since local variables cannot be accessed once the current method activation finishes, the compiler has to go out of its way to generate a new class which acts as a home for any variable whose lifetime needs to be extended past the activation of the procedure. Take the following example:     Random generator = new Random();     Func func = () = generator.Next(10); In this case, the compiler generates a new class called c_DisplayClass1 which is marked with the CompilerGenerated attribute. [CompilerGenerated] private sealed class c__DisplayClass1 {     // Fields     public Random generator;     // Methods     public int b__0()     {         return this.generator.Next(10);     } } Two quick comments on this: (i)    A display was the means that compilers for languages like Algol recorded the various lexical contours of the nested procedure activations on the stack. I imagine that this is what has led to the name. (ii)    It is a shame that the same attribute is used to mark all compiler generated classes as it makes it hard to figure out what they are being used for. Indeed, you could imagine optimisations that the runtime could perform if it knew that classes corresponded to certain high level concepts. We can see that the local variable generator has been turned into a field in the class, and the body of the lambda expression has been turned into a method of the new class. The code that builds the Func object simply constructs an instance of this class and initialises the fields to their initial values.     c__DisplayClass1 class2 = new c__DisplayClass1();     class2.generator = new Random();     Func func = new Func(class2.b__0); Reflector already contains code to spot this pattern of code and reproduce the form containing the lambda expression, so this is example is correctly decompiled. The use of compiler generated code is even more spectacular in the case of iterators. C# introduced the idea of a method that could automatically store its state between calls, so that it can pick up where it left off. The code can express the logical flow with yield return and yield break denoting places where the method should return a particular value and be prepared to resume.         {             yield return 1;             yield return 2;             yield return 3;         } Of course, there was already a .NET pattern for expressing the idea of returning a sequence of values with the computation proceeding lazily (in the sense that the work for the next value is executed on demand). This is expressed by the IEnumerable interface with its Current property for fetching the current value and the MoveNext method for forcing the computation of the next value. The sequence is terminated when this method returns false. The C# compiler links these two ideas together so that an IEnumerator returning method using the yield keyword causes the compiler to produce the implementation of an Iterator. Take the following piece of code.         IEnumerable GetItems()         {             yield return 1;             yield return 2;             yield return 3;         } The compiler implements this by defining a new class that implements a state machine. This has an integer state that records which yield point we should go to if we are resumed. It also has a field that records the Current value of the enumerator and a field for recording the thread. This latter value is used for optimising the creation of iterator instances. [CompilerGenerated] private sealed class d__0 : IEnumerable, IEnumerable, IEnumerator, IEnumerator, IDisposable {     // Fields     private int 1__state;     private int 2__current;     public Program 4__this;     private int l__initialThreadId; The body gets converted into the code to construct and initialize this new class. private IEnumerable GetItems() {     d__0 d__ = new d__0(-2);     d__.4__this = this;     return d__; } When the class is constructed we set the state, which was passed through as -2 and the current thread. public d__0(int 1__state) {     this.1__state = 1__state;     this.l__initialThreadId = Thread.CurrentThread.ManagedThreadId; } The state needs to be set to 0 to represent a valid enumerator and this is done in the GetEnumerator method which optimises for the usual case where the returned enumerator is only used once. IEnumerator IEnumerable.GetEnumerator() {     if ((Thread.CurrentThread.ManagedThreadId == this.l__initialThreadId)               && (this.1__state == -2))     {         this.1__state = 0;         return this;     } The state machine itself is implemented inside the MoveNext method. private bool MoveNext() {     switch (this.1__state)     {         case 0:             this.1__state = -1;             this.2__current = 1;             this.1__state = 1;             return true;         case 1:             this.1__state = -1;             this.2__current = 2;             this.1__state = 2;             return true;         case 2:             this.1__state = -1;             this.2__current = 3;             this.1__state = 3;             return true;         case 3:             this.1__state = -1;             break;     }     return false; } At each stage, the current value of the state is used to determine how far we got, and then we generate the next value which we return after recording the next state. Finally we return false from the MoveNext to signify the end of the sequence. Of course, that example was really simple. The original method body didn't have any local variables. Any local variables need to live between the calls to MoveNext and so they need to be transformed into fields in much the same way that we did in the case of the lambda expression. More complicated MoveNext methods are required to deal with resources that need to be disposed when the iterator finishes, and sometimes the compiler uses a temporary variable to hold the return value. Why all of this explanation? We've implemented the de-compilation of iterators in the current EAP version of Reflector (7). This contrasts with previous version where all you could do was look at the MoveNext method and try to figure out the control flow. There's a fair amount of things we have to do. We have to spot the use of a CompilerGenerated class which implements the Enumerator pattern. We need to go to the class and figure out the fields corresponding to the local variables. We then need to go to the MoveNext method and try to break it into the various possible states and spot the state transitions. We can then take these pieces and put them back together into an object model that uses yield return to show the transition points. After that Reflector can carry on optimising using its usual optimisations. The pattern matching is currently a little too sensitive to changes in the code generation, and we only do a limited analysis of the MoveNext method to determine use of the compiler generated fields. In some ways, it is a pity that iterators are compiled away and there is no metadata that reflects the original intent. Without it, we are always going to dependent on our knowledge of the compiler's implementation. For example, we have noticed that the Async CTP changes the way that iterators are code generated, so we'll have to do some more work to support that. However, with that warning in place, we seem to do a reasonable job of decompiling the iterators that are built into the framework. Hopefully, the EAP will give us a chance to find examples where we don't spot the pattern correctly or regenerate the wrong code, and we can improve things. Please give it a go, and report any problems.

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• Google Analytics on Android

  - by pjv

  There is a specific and official analytics SDK for native Android apps (note that I'm not talking about webpages in apps on a phone). This library basically sends pages and events to Google Analytics and you can view your analytics in exactly the same dashboard as for websites. Since my background is apps rather than websites, and since a lot of the Google Analytics terminology seems particularly inapplicable to a native app, I need some pointers. Please discuss my remarks, provide some clarification where you think I'm off-track, and above all share good experiences! 1. Page Views Pages mostly can match different Activities (and Dialogs) being displayed. Activities can be visible behind non-full-screen Activities however, though only the top-level Activity can be interacted. This sort-off clashes with a "(page) view". You'd also want at least one page view for each visit and therefore put one page view tracker in the Application class. However this does not constitute a window or sorts. Usually an Activity will open at the same time, so the time spent on that page will have been 0. This will influence your "time spent" statistics. How are these counted anyway? Moreover, there is a loose coupling between the Activities, by means of Intents. A user can, much like on any website, step in at any Activity, although usually this then concerns resuming the application where he left off. This makes that the hierarchy of Activities usually is very flat. And since there are no url's involved. What meaning would using slashes in page titles have, such as "/Home"? All pages would appear on an equal level in the reports, so no content drilldown. Non-unique page views seem to be counted as some kind of indicator of successfulness: how often does the visitor revisit the page. When the user rotates the screen however usually an Activity resumes again, thus making it a new page view. This happens a lot. Maybe a well-thought-through placement of the call might solve this, or placing several, I'm not sure. How to deal with Page Views? 2. Events I'd say there are two sorts: A user event Something that happened, usually as an indirect consequence of the above. The latter particularly is giving me headaches. First of all, many events aren't written in code any more, but pieced logically together by means of Intents. This means that there is no place to put the analytics call. You'd either have to give up this advantage and start doing it the old-fashioned way in favor of good analytics, or, just be missing some events. Secondly, as a developer you're not so much interested in when a user clicks a button, but if the action that should have been performed really was performed and what the result was. There seems to be no clear way to get resulting data into Google Analytics (what's up with the integers? I want to put in Strings!). The same that applies to the flat pages hierarchy, also goes for the event categories. You could do "vertical" categories (topically, that is), but some code is shared "horizontally" and the tracking will be equally shared. Just as with the Intents mechanism, inheritance makes it hard for you to put the tracking in the right places at all times. And I can't really imagine "horizontal" categories. Unless you start making really small categories, such as all the items form the same menu in one category, I have a hard time grasping the concept. Finally, how do you deal with cancelling? Usually you both have an explicit cancel mechanism by ways of a button, as well as the implicit cancel when the "back"-button is pressed to leave the activity and there were no changes. The latter also applies to "saves", when the back button is pressed and there ARE changes. How are you consequently going to catch all these if not by doing all the "back"-button work yourself? How to deal with events? 3. Goals For goal types I have choice of: URL Destination, Time on Site, and Pages/Visit. Most apps don't have a funnel that leads the user to some "registration done" or "order placed" page. Apps have either already been bought (in which case you want to stimulate the user to love your app, so that he might bring on new buyers) or are paid for by in-app ads. So URL Destination is not a very important goal. Time on Site also seems troublesome. First, I have some doubt on how this would be measured. Second, I don't necessarily want my user to spend a lot of time in my already paid app, just be active and content. Equivalently, why not mention how frequent a user uses your app? Regarding Pages/Visit I already mentioned how screen orientation changes blow up the page view numbers. In an app I'd be most interested in events/visit to measure the user's involvement/activity. If he's intensively using the app then he must be loving it right? Furthermore, I also have some small funnels (that do not lead to conversion though) that I want to see streamlined. In my mind those funnels would end in events rather than page views but that seems not to be possible. I could also measure clickthroughs on in-app ads, but then I'd need to track those as Page Views rather than Events, in view of "URL Destination". What are smart goals for apps and how can you fit them on top of Analytics? 4. Optimisation Is there a smart way to manually do what "Website Optimiser" does for websites? Most importantly, how would I track different landing page designs? 5. Traffic Sources Referrals deal with installation time referrals, if you're smart enough to get them included. But perhaps I'd also want to get some data which third-party app sends users to my app to perform some actions (this app interoperability is possible via Intents). Many of the terminologies related to "Traffic Sources" seem totally meaningless and there is no possibility of connecting in AdSense. What are smart uses of this data? 6. Visitors Of the "Browser capabilities", "Network Properties" and "Mobile" tabs, many things are pointless as they have no influence on / relation with my mostly offline app that won't use flash anyway. Only if you drill down far enough, can you get to OS versions, which do matter a lot. I even forgot where you could check what exact Android devices visited. What are smart uses of this data? How can you make the relevant info more prominent? 7. Other No in-page analytics. I have to register my app as a web-url (What!?)?

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• Bad disks in ancient server

  - by Joel Coel

  I have a 1998-era Netware 3.12 server that runs everything on our campus: general ledger, purchasing, payroll, student information, grades, you name it. The server has an Adaptec RAID controller with two volumes: RAID 1, 2 17GB scsi disks, Seagate ST318417W RAID 5, 3 4GB scsi disks, 2 Seagate ST34573W and 1 ST34572W. We are currently in the early stages of a project to replace this system, but you don't just jump into a new system like that and so I need to keep this server running until at least November 2011. This week we had not one but two hard drives fail. Thankfully they are from different volumes and we're able to keep running for the moment, but given the close nature of these failures I have serious doubts that I'll be able to avoid catastrophic failure from this server through the November target as is without restoring the RAID redundancy — it'll only take one more drive failure anywhere and I'm completely hosed. We are fortunate enough to have exact match "spares" lying around for both drives, but the spares are in unknown condition. I tried swapping just them in, but the RAID controller isn't smart enough to handle this and it renders the system unbootable. As for the RAID controller itself, there is utility I can get into during POST via a Ctrl-A shortcut, but I can't do much useful from there. To actually manage volumes I must first boot in to Netware, at which point I can use CI/O Array Management Software Version 2.0 to actually look at volume information. I suspect that the normal way to manage things is to boot from a special floppy with the controller software on it, but that floppy is long gone. Going through the options in the RAID software, I think the only supported way to replace a disk in an existing RAID volume is to physically add the disk, boot up and configure it as a "spare" for a volume, force the volume to use the spare to replace an existing down disk (and at this point I'm only guessing) so that the down disk becomes the spare, repair the volume, remove the spare from the volume, and then shut down and remove the disk. Then start all over for the other failed disk. All this amounts to a lot of downtime, assuming I can even make it work and that my spares are any good. As for finding reliable spares, I have no clue where to even begin looking to find a new 4GB scsi drive, or even which exact scsi system I'm looking for, as it's gone through a few different iterations over time. Another option is to migrate this to a virtual machine (hyper-v), but all previous attempts we've made in this area have failed to get very far. When this machine was installed I was just graduating from high school, and so it requires lower level knowledge of netware and dos than I ever developed, or if I did have since forgotten (I'm not exactly a dos neophyte, either). Part of my problem is this is a high-use server, and taking it down for a few days to figure things out isn't gonna fly very well. As for the question, I'm looking for anything that might be helpful in this situation: a recommendation on a place to find good spares from this era, personal experience repairing RAID volumes using a similar controller or building a hyper-v vm from an old netware server, a line on a floppy with better software for the RAID controller, recommendation on a good Novell consultant in Nebraska that would be able to put things right, a whole other option I haven't considered yet, etc. Update: For backups, we have good (recently verified via restore) backups of the data only -- nothing for the software that actually runs things. Update 2: Just a progress report that I currently have a working Netware 3.12 install in VMWare Virtual Server 2.0, thanks largely to the guide I found here: http://cerbulescubogdan.blogspot.com/2010/11/novell-netware-312-on-vmware.html The next steps are preparing empty netware volumes to match the additional volumes on my existing server, taking a dump of everything on the C:\ drive and netware volumes on my existing server, and figuring out from that information what modules need added to netware, installing my licenses (we do still have that disk, if it's any good), and moving data over. I have approval to bring the server down for a week after the first of the year (sadly not before), so, aside from creating empty volumes, the rest of the work will have to wait until then. Final Update (Jan 5, 2011): I was able to get spares working in both raid arrays without data loss this week. Both are now listed by the controller as "FAULT TOLLERANT" (yay!). I was also able to build on the progress from my last update and now have a functional "spare" server in VMWare Server 2.0. The spare can run and use our erp software, but I can't put it into production because I can't (yet) print from that box (and I have no idea why). Even so, this VM will do in a pinch if I have no other choice, and between it and the repaired RAID arrays I'm comfortable pushing on until I can junk the machine in November.

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• Server hung with "blocked for more than 120 seconds", diskless

  - by alterpub

  I have server which hung every 2-5 days. dmesg show following situation: kernel: [490894.231753] INFO: task munin-html:10187 blocked for more than 120 seconds. kernel: [490894.231799] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kernel: [490894.231843] munin-html D 0000000000000000 0 10187 9796 0x00000000 kernel: [490894.231878] ffff88063174b968 0000000000000082 ffff88063174b8d8 0000000000015b80 kernel: [490894.231930] ffff88063174bfd8 0000000000015b80 ffff88063174bfd8 ffff88062fe644d0 kernel: [490894.231982] 0000000000015b80 0000000000015b80 ffff88063174bfd8 0000000000015b80 kernel: [490894.232033] Call Trace: kernel: [490894.232059] [<ffffffff8117fce0>] ? sync_buffer+0x0/0x50 kernel: [490894.232089] [<ffffffff815a1f13>] io_schedule+0x73/0xc0 kernel: [490894.232115] [<ffffffff8117fd25>] sync_buffer+0x45/0x50 kernel: [490894.232143] [<ffffffff815a258f>] __wait_on_bit+0x5f/0x90 kernel: [490894.232170] [<ffffffff8117fce0>] ? sync_buffer+0x0/0x50 kernel: [490894.232197] [<ffffffff815a2638>] out_of_line_wait_on_bit+0x78/0x90 kernel: [490894.232227] [<ffffffff81080250>] ? wake_bit_function+0x0/0x40 kernel: [490894.232255] [<ffffffff8117fcd6>] __wait_on_buffer+0x26/0x30 kernel: [490894.232288] [<ffffffffa00131be>] squashfs_read_data+0x1be/0x520 [squashfs] kernel: [490894.232320] [<ffffffff8114f0f1>] ? __mem_cgroup_try_charge+0x71/0x450 kernel: [490894.232350] [<ffffffffa0013963>] squashfs_cache_get+0x1c3/0x320 [squashfs] kernel: [490894.232381] [<ffffffffa00136eb>] ? squashfs_copy_data+0x10b/0x130 [squashfs] kernel: [490894.232426] [<ffffffff815a3dbe>] ? _raw_spin_lock+0xe/0x20 kernel: [490894.232454] [<ffffffffa0013b68>] ? squashfs_read_metadata+0x48/0xf0 [squashfs] kernel: [490894.232499] [<ffffffffa0013ae1>] squashfs_get_datablock+0x21/0x30 [squashfs] kernel: [490894.232544] [<ffffffffa0015026>] squashfs_readpage+0x436/0x4a0 [squashfs] kernel: [490894.232575] [<ffffffff8111a375>] ? __inc_zone_page_state+0x35/0x40 kernel: [490894.232606] [<ffffffff8110d072>] __do_page_cache_readahead+0x172/0x210 kernel: [490894.232636] [<ffffffff8110d131>] ra_submit+0x21/0x30 kernel: [490894.232662] [<ffffffff811045f3>] filemap_fault+0x3f3/0x450 kernel: [490894.232691] [<ffffffff812bd156>] ? prio_tree_insert+0x256/0x2b0 kernel: [490894.232726] [<ffffffffa009225d>] aufs_fault+0x11d/0x170 [aufs] kernel: [490894.232755] [<ffffffff8111f6d4>] __do_fault+0x54/0x560 kernel: [490894.232782] [<ffffffff81122f39>] handle_mm_fault+0x1b9/0x440 kernel: [490894.232811] [<ffffffff811286f5>] ? do_mmap_pgoff+0x335/0x380 kernel: [490894.232840] [<ffffffff815a7af5>] do_page_fault+0x125/0x350 kernel: [490894.232867] [<ffffffff815a4675>] page_fault+0x25/0x30 Os info cat /etc/issue.net Ubuntu 10.04.2 LTS uname -a Linux Shard1Host3 2.6.35-32-server #68~lucid1-Ubuntu SMP Wed Mar 28 18:33:00 UTC 2012 x86_64 GNU/Linux This system load via ltsp and hasn't harddrives also it has a lot of memory 24Gb. free -m total used free shared buffers cached Mem: 24152 17090 7061 0 50 494 -/+ buffers/cache: 16545 7607 Swap: 0 0 0 I put vmstat info here but I think it won't give results after reboot vmstat 1 30 procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu---- r b swpd free buff cache si so bi bo in cs us sy id wa 0 0 0 7231156 52196 506400 0 0 0 0 172 143 7 0 92 0 1 0 0 7231024 52196 506400 0 0 0 0 7859 16233 5 0 94 0 0 0 0 7231024 52196 506400 0 0 0 0 7870 16446 2 0 98 0 0 0 0 7230900 52196 506400 0 0 0 0 7308 15661 5 0 95 0 0 0 0 7231100 52196 506400 0 0 0 0 7960 16543 6 0 94 0 0 0 0 7231100 52196 506400 0 0 0 0 7542 16047 5 1 94 0 3 0 0 7231100 52196 506400 0 0 0 0 7709 16621 3 0 96 0 0 0 0 7231220 52196 506400 0 0 0 0 7857 16552 4 0 96 0 0 0 0 7231220 52196 506400 0 0 0 0 7192 15491 6 0 94 0 0 0 0 7231220 52196 506400 0 0 0 0 7423 15792 5 1 94 0 1 0 0 7231260 52196 506404 0 0 0 0 7686 16296 2 0 98 0 0 0 0 7231260 52196 506404 0 0 0 0 6976 15183 5 0 95 0 0 0 0 7231260 52196 506404 0 0 0 0 7303 15600 4 0 95 0 0 0 0 7231320 52196 506404 0 0 0 0 7967 16241 1 0 98 0 0 0 0 7231444 52196 506404 0 0 0 0 6948 15113 6 0 94 0 0 0 0 7231444 52196 506404 0 0 0 0 7931 16181 6 0 94 0 1 0 0 7231516 52196 506404 0 0 0 0 7715 15829 6 0 94 0 0 0 0 7231516 52196 506404 0 0 0 0 7771 16036 2 0 97 0 0 0 0 7231268 52196 506404 0 0 0 0 7782 16202 6 0 94 0 1 0 0 7231212 52196 506404 0 0 0 0 7457 15622 4 0 96 0 0 0 0 7231212 52196 506404 0 0 0 0 7573 16045 2 0 98 0 2 0 0 7231216 52196 506404 0 0 0 0 7689 16076 6 0 94 0 0 0 0 7231424 52196 506404 0 0 0 0 7429 15650 4 0 95 0 3 0 0 7231424 52196 506404 0 0 0 0 7534 16168 3 0 97 0 1 0 0 7230548 52196 506404 0 0 0 0 8559 15926 7 1 92 0 0 0 0 7230672 52196 506404 0 0 0 0 7720 15905 2 0 98 0 0 0 0 7230548 52196 506404 0 0 0 0 7677 16313 5 0 95 0 1 0 0 7230676 52196 506404 0 0 0 0 7209 15432 5 0 95 0 0 0 0 7230800 52196 506404 0 0 0 0 7522 15861 2 0 98 0 0 0 0 7230552 52196 506404 0 0 0 0 7760 16661 5 0 95 0 In the munin(monitoring system) graphs I see(before server hung): Disk(nbd0) IOs per device: read: 289m but avg by week 2.09m Disk(nbd0) throughput per device: read: 4.73k but avg by week 108.76 Disk(nbd0) utilization per device: 100% but avg by week 1.2% Eth0 traffic was low: in/out only 2Mbps Number of threads increased to 566 usually 392 Fork rate 1.08 but usually 2.82 VMStat(processes state) Increased to 17.77(from 0 as far as I could see in the graph) CPU usage iowait 880.46% when usually 6.67% It'll be great if somebody help me to understand what's up.

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• Need personal advice on how to get out of a company..

  - by SOfan

  Hi, I am an SO user since past 6 months and this is the first time I am turning to SO for personal help. I have asked technical questions before with my real ID. I am stuck inside a service based IT company for the past one year and haven't been able to decide if to leave it, when to leave it and how to leave it. I had taken 2 weeks LWP on medical reason roughly at end of 1 year and then soon after reporting, I applied for 2 months more LWP (on medical/personal ground) with the intention of working on my health,take up a hobby class to ward off depression,pessimism, to have some fun in life, and to look for a job which I really would be excited about - that interests me and which matches with my strength. My leave starts from this Monday. So in any case, I had hard set in mind that I will leave the company after I join them back hopefully with some job offer already in hand (after figuring out what I want do). Neither I can stand the past project,past colleagues,company, HR, pathetically low salary. But if I really listen to my heart, I don't want to have to go back to that office after my sabbatical and again have to see those people. I will have to resign it after my sabbatical ends. Then HR people perhaps wont like it, may even accuse me on face or behind back that primary purpose of my leave must have been to hunt for a better job and I lied about medical and person reasons. Also, if they get nasty and force me to serve 2 months notice period. There is no way I see myself after sabbatical resuming in old project or starting new work. It will be a pain. Since they have already approved 2 months leave and stuff, ideally if they want, they should be just able to relieve me right on the next day after I join back. But, I don't know if they want to get nasty, will they mention about my 2 months sabbatical leave in my experience letter or more scary, the term medical/personal reason. I have hard earned my experience here, have worked against my will, mostly it has been painful and slogged like anything, because I realize the importance of work experience in IT industry. I don't have greed to have those 2 months included extra in my experience letter, but I don't want to mess up with my experience letter in a way which makes my next employer ask question, get suspicious, or be wary if I have any medical reason going on. Being an emotional,moody person or somebody who can't be in an environment, once my mind and heart starts hating it. I think it perhaps is best, if I resign on Monday itself telling them (in polite manner) something that look I took sabbatical for some reason but I don't want to resume working in the company after my sabbatical ends. So please accept my resignation. Now tell me what you want to do about my leave request, my notice period and when you are willing to relieve me. What should I write and how? Some background: I am working in an IT company in India.I am overqualified in the company. It is grossly underpaying me. My education qualifications far exceed anyone's in the whole company being a CS undergrad as well as a CS grad. I joined this company after finishing the grad. I had self-doubts about my skills and interest as a programmer. I like doing research oriented work, though didn't have any particular success during grad. My life here has been very hectic. The project containing many many sub-projects has kept me on my toes and I have never really liked the work. I have been playing against my strength. Also the company strict internet usage policy (you can't read gmails, can't browse any non-work related sites not even news). When working for a client, from the machine we can't even check company related emails.For this one has to go to kiosk like 5 machines in a small room etc. Most of the times those machines are not available, so it was not unusual to keep making rounds to these kiosk machines to check company emails, browse company related emails etc.So it was not so easy to keep in touch with company related basic affairs for a not particular careful person. Things like this which are new to me, make me feel restricted. I am an undecisive person with a sense of failure, self-doubt, not meeting up unrealistic expectation. Somewhere at back of mind, I envy my classmates who make a smooth transition from company to company without causing any gap in their resume. I on other hand have gaps in resume. I get tired after working in a place for sometime. problem with colleagues in general. I am not particular great with people, have few friends, not known for a fun nature, rather serious, scholar. I am not a typical conventional female. I think females are usually more disciplined. But I am not so. I reach office late (though after informing manager). I don't want to blame them entirely, because from my past, it is not unusual for me to get undecisive on things. Also I had doubts about my ability as researched and to succeed there. of building a relationship in a group, to have something to talk about, newspaper. I get cut-off from people. peer pressure. I make blunders in coding, lose patience. Consciously or unconsciously I feel contempt for people here, work here, environment here. I have doubts that either I go to a place which does innovation, does research oriented work, product biggies, have great motivated people, have competent people passionate about products they are building. But then I also doubt my ability to survive there. I have identified that an idea job for me would be 4 days a week, a high salary job. When among people in company/team, I can't think much. I need some time at home to read good authentic books written in good style on what work I am doing.So that I am comfortable with my understanding of work. I get into pressure easily under deadline and need 5th day to cool myself off. I took for 2 weeks leave, because each day was hell for me. May be the depression phase of bipolar is on and also partially it could be that being a work centered person, who derives happiness,self-esteem from work, haven't been enjoying work and have been working for the sole person of proving stability, and ability to stick, against all odds, and facing what challenges I see, bonding with people, identifying opportunities to learn in given task etc.have been averaging one day LWP in 1 week or 10 days. or may be because of my nature,ADD,not being able to switch context,out of touch with news, don't have a circle of friends with who I enjoy. less knowledge in general to talk about, just some technical stuff.anyway, so due to emotional reason, some practical reason etc, I wanted to be very sure before leaving. So my leave starts from Monday and I should feel happy about it. I have taken the leave to for a few purposes - to take care of my health by regular yoga/exercise (with project on, I just can't do anything regular), reassess myself to see what I want to try next which work I might like, look for next job, take up a hobby which I like say singing. I am not clear on my career,job aspiration. I have tried my hands on research. During this year appraisal yesterday, I even had some conflict with my last manager. In meeting with me one on one, he would say all nice things about me, but in feedback to new manager, he hasn't given any excellent feedback. It is all only good. I am angry at this old Manager. Also new manager also scolded me as I didn't agree to his appraisal and waited to hear myself from old Manager. He kind of scolded me for wasting his time. Am I being unethical somewhere? I am always very conscious of if I am cheating anywhere. What advice I am seeking? How to resign and what to write in resignation letter

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• Working with Timelines with LINQ to Twitter

  - by Joe Mayo

  When first working with the Twitter API, I thought that using SinceID would be an effective way to page through timelines. In practice it doesn’t work well for various reasons. To explain why, Twitter published an excellent document that is a must-read for anyone working with timelines: Twitter Documentation: Working with Timelines This post shows how to implement the recommended strategies in that document by using LINQ to Twitter. You should read the document in it’s entirety before moving on because my explanation will start at the bottom and work back up to the top in relation to the Twitter document. What follows is an explanation of SinceID, MaxID, and how they come together to help you efficiently work with Twitter timelines. The Role of SinceID Specifying SinceID says to Twitter, “Don’t return tweets earlier than this”. What you want to do is store this value after every timeline query set so that it can be reused on the next set of queries.  The next section will explain what I mean by query set, but a quick explanation is that it’s a loop that gets all new tweets. The SinceID is a backstop to avoid retrieving tweets that you already have. Here’s some initialization code that includes a variable named sinceID that will be used to populate the SinceID property in subsequent queries: // last tweet processed on previous query set ulong sinceID = 210024053698867204; ulong maxID; const int Count = 10; var statusList = new List<status>(); Here, I’ve hard-coded the sinceID variable, but this is where you would initialize sinceID from whatever storage you choose (i.e. a database). The first time you ever run this code, you won’t have a value from a previous query set. Initially setting it to 0 might sound like a good idea, but what if you’re querying a timeline with lots of tweets? Because of the number of tweets and rate limits, your query set might take a very long time to run. A caveat might be that Twitter won’t return an entire timeline back to Tweet #0, but rather only go back a certain period of time, the limits of which are documented for individual Twitter timeline API resources. So, to initialize SinceID at too low of a number can result in a lot of initial tweets, yet there is a limit to how far you can go back. What you’re trying to accomplish in your application should guide you in how to initially set SinceID. I have more to say about SinceID later in this post. The other variables initialized above include the declaration for MaxID, Count, and statusList. The statusList variable is a holder for all the timeline tweets collected during this query set. You can set Count to any value you want as the largest number of tweets to retrieve, as defined by individual Twitter timeline API resources. To effectively page results, you’ll use the maxID variable to set the MaxID property in queries, which I’ll discuss next. Initializing MaxID On your first query of a query set, MaxID will be whatever the most recent tweet is that you get back. Further, you don’t know what MaxID is until after the initial query. The technique used in this post is to do an initial query and then use the results to figure out what the next MaxID will be.  Here’s the code for the initial query: var userStatusResponse = (from tweet in twitterCtx.Status where tweet.Type == StatusType.User && tweet.ScreenName == "JoeMayo" && tweet.SinceID == sinceID && tweet.Count == Count select tweet) .ToList(); statusList.AddRange(userStatusResponse); // first tweet processed on current query maxID = userStatusResponse.Min( status => ulong.Parse(status.StatusID)) - 1; The query above sets both SinceID and Count properties. As explained earlier, Count is the largest number of tweets to return, but the number can be less. A couple reasons why the number of tweets that are returned could be less than Count include the fact that the user, specified by ScreenName, might not have tweeted Count times yet or might not have tweeted at least Count times within the maximum number of tweets that can be returned by the Twitter timeline API resource. Another reason could be because there aren’t Count tweets between now and the tweet ID specified by sinceID. Setting SinceID constrains the results to only those tweets that occurred after the specified Tweet ID, assigned via the sinceID variable in the query above. The statusList is an accumulator of all tweets receive during this query set. To simplify the code, I left out some logic to check whether there were no tweets returned. If  the query above doesn’t return any tweets, you’ll receive an exception when trying to perform operations on an empty list. Yeah, I cheated again. Besides querying initial tweets, what’s important about this code is the final line that sets maxID. It retrieves the lowest numbered status ID in the results. Since the lowest numbered status ID is for a tweet we already have, the code decrements the result by one to keep from asking for that tweet again. Remember, SinceID is not inclusive, but MaxID is. The maxID variable is now set to the highest possible tweet ID that can be returned in the next query. The next section explains how to use MaxID to help get the remaining tweets in the query set. Retrieving Remaining Tweets Earlier in this post, I defined a term that I called a query set. Essentially, this is a group of requests to Twitter that you perform to get all new tweets. A single query might not be enough to get all new tweets, so you’ll have to start at the top of the list that Twitter returns and keep making requests until you have all new tweets. The previous section showed the first query of the query set. The code below is a loop that completes the query set: do { // now add sinceID and maxID userStatusResponse = (from tweet in twitterCtx.Status where tweet.Type == StatusType.User && tweet.ScreenName == "JoeMayo" && tweet.Count == Count && tweet.SinceID == sinceID && tweet.MaxID == maxID select tweet) .ToList(); if (userStatusResponse.Count > 0) { // first tweet processed on current query maxID = userStatusResponse.Min( status => ulong.Parse(status.StatusID)) - 1; statusList.AddRange(userStatusResponse); } } while (userStatusResponse.Count != 0 && statusList.Count < 30); Here we have another query, but this time it includes the MaxID property. The SinceID property prevents reading tweets that we’ve already read and Count specifies the largest number of tweets to return. Earlier, I mentioned how it was important to check how many tweets were returned because failing to do so will result in an exception when subsequent code runs on an empty list. The code above protects against this problem by only working with the results if Twitter actually returns tweets. Reasons why there wouldn’t be results include: if the first query got all the new tweets there wouldn’t be more to get and there might not have been any new tweets between the SinceID and MaxID settings of the most recent query. The code for loading the returned tweets into statusList and getting the maxID are the same as previously explained. The important point here is that MaxID is being reset, not SinceID. As explained in the Twitter documentation, paging occurs from the newest tweets to oldest, so setting MaxID lets us move from the most recent tweets down to the oldest as specified by SinceID. The two loop conditions cause the loop to continue as long as tweets are being read or a max number of tweets have been read.  Logically, you want to stop reading when you’ve read all the tweets and that’s indicated by the fact that the most recent query did not return results. I put the check to stop after 30 tweets are reached to keep the demo from running too long – in the console the response scrolls past available buffer and I wanted you to be able to see the complete output. Yet, there’s another point to be made about constraining the number of items you return at one time. The Twitter API has rate limits and making too many queries per minute will result in an error from twitter that LINQ to Twitter raises as an exception. To use the API properly, you’ll have to ensure you don’t exceed this threshold. Looking at the statusList.Count as done above is rather primitive, but you can implement your own logic to properly manage your rate limit. Yeah, I cheated again. Summary Now you know how to use LINQ to Twitter to work with Twitter timelines. After reading this post, you have a better idea of the role of SinceID - the oldest tweet already received. You also know that MaxID is the largest tweet ID to retrieve in a query. Together, these settings allow you to page through results via one or more queries. You also understand what factors affect the number of tweets returned and considerations for potential error handling logic. The full example of the code for this post is included in the downloadable source code for LINQ to Twitter.   @JoeMayo

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• Execution plan warnings–The final chapter

  - by Dave Ballantyne

  In my previous posts (here and here), I showed examples of some of the execution plan warnings that have been added to SQL Server 2012.  There is one other warning that is of interest to me : “Unmatched Indexes”. Firstly, how do I know this is the final one ?  The plan is an XML document, right ? So that means that it can have an accompanying XSD.  As an XSD is a schema definition, we can poke around inside it to find interesting things that *could* be in the final XML file. The showplan schema is stored in the folder Microsoft SQL Server\110\Tools\Binn\schemas\sqlserver\2004\07\showplan and by comparing schemas over releases you can get a really good idea of any new functionality that has been added. Here is the section of the Sql Server 2012 showplan schema that has been interesting me so far : <xsd:complexType name="AffectingConvertWarningType"> <xsd:annotation> <xsd:documentation>Warning information for plan-affecting type conversion</xsd:documentation> </xsd:annotation> <xsd:sequence> <!-- Additional information may go here when available --> </xsd:sequence> <xsd:attribute name="ConvertIssue" use="required"> <xsd:simpleType> <xsd:restriction base="xsd:string"> <xsd:enumeration value="Cardinality Estimate" /> <xsd:enumeration value="Seek Plan" /> <!-- to be extended here --> </xsd:restriction> </xsd:simpleType> </xsd:attribute> <xsd:attribute name="Expression" type ="xsd:string" use="required" /></xsd:complexType><xsd:complexType name="WarningsType"> <xsd:annotation> <xsd:documentation>List of all possible iterator or query specific warnings (e.g. hash spilling, no join predicate)</xsd:documentation> </xsd:annotation> <xsd:choice minOccurs="1" maxOccurs="unbounded"> <xsd:element name="ColumnsWithNoStatistics" type="shp:ColumnReferenceListType" minOccurs="0" maxOccurs="1" /> <xsd:element name="SpillToTempDb" type="shp:SpillToTempDbType" minOccurs="0" maxOccurs="unbounded" /> <xsd:element name="Wait" type="shp:WaitWarningType" minOccurs="0" maxOccurs="unbounded" /> <xsd:element name="PlanAffectingConvert" type="shp:AffectingConvertWarningType" minOccurs="0" maxOccurs="unbounded" /> </xsd:choice> <xsd:attribute name="NoJoinPredicate" type="xsd:boolean" use="optional" /> <xsd:attribute name="SpatialGuess" type="xsd:boolean" use="optional" /> <xsd:attribute name="UnmatchedIndexes" type="xsd:boolean" use="optional" /> <xsd:attribute name="FullUpdateForOnlineIndexBuild" type="xsd:boolean" use="optional" /></xsd:complexType> I especially like the “to be extended here” comment,  high hopes that we will see more of these in the future.   So “Unmatched Indexes” was a warning that I couldn’t get and many thanks must go to Fabiano Amorim (b|t) for showing me the way.   Filtered indexes were introduced in Sql Server 2008 and are really useful if you only need to index only a portion of the data within a table.  However,  if your SQL code uses a variable as a predicate on the filtered data that matches the filtered condition, then the filtered index cannot be used as, naturally,  the value in the variable may ( and probably will ) change and therefore will need to read data outside the index.  As an aside,  you could use option(recompile) here , in which case the optimizer will build a plan specific to the variable values and use the filtered index,  but that can bring about other problems.   To demonstrate this warning, we need to generate some test data :   DROP TABLE #TestTab1GOCREATE TABLE #TestTab1 (Col1 Int not null, Col2 Char(7500) not null, Quantity Int not null)GOINSERT INTO #TestTab1 VALUES (1,1,1),(1,2,5),(1,2,10),(1,3,20), (2,1,101),(2,2,105),(2,2,110),(2,3,120)GO and then add a filtered index CREATE INDEX ixFilter ON #TestTab1 (Col1)WHERE Quantity = 122 Now if we execute SELECT COUNT(*) FROM #TestTab1 WHERE Quantity = 122 We will see the filtered index being scanned But if we parameterize the query DECLARE @i INT = 122SELECT COUNT(*) FROM #TestTab1 WHERE Quantity = @i The plan is very different a table scan, as the value of the variable used in the predicate can change at run time, and also we see the familiar warning triangle. If we now look at the properties pane, we will see two pieces of information “Warnings” and “UnmatchedIndexes”. So, handily, we are being told which filtered index is not being used due to parameterization.

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