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• Building a Data Mart with Pentaho Data Integration Video Review by Diethard Steiner, Packt Publishing

  - by Compudicted

  Originally posted on: http://geekswithblogs.net/Compudicted/archive/2014/06/01/building-a-data-mart-with-pentaho-data-integration-video-review.aspx The Building a Data Mart with Pentaho Data Integration Video by Diethard Steiner from Packt Publishing is more than just a course on how to use Pentaho Data Integration, it also implements and uses the principals of the Data Warehousing (and I even heard the name of Ralph Kimball in the video). Indeed, a video watcher should be familiar with its concepts as the Star Schema, Slowly Changing Dimension types, etc. so I suggest prior to watching this course to consider skimming through the Data Warehouse concepts (if unfamiliar) or even better, read the excellent Ralph’s The Data Warehouse Tooolkit. By the way, the author expands beyond using Pentaho along to MySQL and MonetDB which is a real icing on the cake! Indeed, I even suggest the name of the course should be ‘Building a Data Warehouse with Pentaho’. To successfully complete the course one needs to know some Linux (Ubuntu used in the course), the VI editor and the Bash command shell, but it seems that similar requirements would also apply to the Weindows OS. Additionally, knowing some basic SQL would not hurt. As I had said, MonetDB is used in this course several times which seems to be not anymore complex than say MySQL, but based on what I read is very well suited for fast querying big volumes of data thanks to having a columnstore (vertical data storage). I don’t see what else can be a barrier, the material is very digestible. On this note, I must add that the author does not cover how to acquire the software, so here is what I found may help: Pentaho: the free Community Edition must be more than anyone needs to learn it. Or even go into a POC. MonetDB can be downloaded (exists for both, Linux and Windows) from http://goo.gl/FYxMy0 (just see the appropriate link on the left). The author seems to be using Eclipse to run SQL code, one can get it from http://goo.gl/5CcuN. To create, or edit database entities and/or schema otherwise one can use a universal tool called SQuirreL, get it from http://squirrel-sql.sourceforge.net.   Next, I must confess Diethard is very knowledgeable in what he does and beyond. However, there will be some accent heard to the user of the course especially if one’s mother tongue language is English, but it I got over it in a few chapters. I liked the rate at which the material is being presented, it makes me feel I paid for every second Eventually, my impressions are: Pentaho is an awesome ETL offering, it is worth learning it very much (I am an ETL fan and a heavy user of SSIS) MonetDB is nice, it tickles my fancy to know it more Data Warehousing, despite all the BigData tool offerings (Hive, Scoop, Pig on Hadoop), using the traditional tools still rocks Chapters 2 to 6 were the most fun to me with chapter 8 being the most difficult.   In terms of closing, I highly recommend this video to anyone who needs to grasp Pentaho concepts quick, likewise, the course is very well suited for any developer on a “supposed to be done yesterday” type of a project. It is for a beginner to intermediate level ETL/DW developer. But one would need to learn more on Data Warehousing and Pentaho, for such I recommend the 5 star Pentaho Data Integration 4 Cookbook. Enjoy it! Disclaimer: I received this video from the publisher for the purpose of a public review.

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• Surviving MATLAB and R as a Hardcore Programmer

  - by dsimcha

  I love programming in languages that seem geared towards hardcore programmers. (My favorites are Python and D.) MATLAB is geared towards engineers and R is geared towards statisticians, and it seems like these languages were designed by people who aren't hardcore programmers and don't think like hardcore programmers. I always find them somewhat awkward to use, and to some extent I can't put my finger on why. Here are some issues I have managed to identify: (Both): The extreme emphasis on vectors and matrices to the extent that there are no true primitives. (Both): The difficulty of basic string manipulation. (Both): Lack of or awkwardness in support for basic data structures like hash tables and "real", i.e. type-parametric and nestable, arrays. (Both): They're really, really slow even by interpreted language standards, unless you bend over backwards to vectorize your code. (Both): They seem to not be designed to interact with the outside world. For example, both are fairly bulky programs that take a while to launch and seem to not be designed to make simple text filter programs easy to write. Furthermore, the lack of good string processing makes file I/O in anything but very standard forms near impossible. (Both): Object orientation seems to have a very bolted-on feel. Yes, you can do it, but it doesn't feel much more idiomatic than OO in C. (Both): No obvious, simple way to get a reference type. No pointers or class references. For example, I have no idea how you roll your own linked list in either of these languages. (MATLAB): You can't put multiple top level functions in a single file, encouraging very long functions and cut-and-paste coding. (MATLAB): Integers apparently don't exist as a first class type. (R): The basic builtin data structures seem way too high level and poorly documented, and never seem to do quite what I expect given my experience with similar but lower level data structures. (R): The documentation is spread all over the place and virtually impossible to browse or search. Even D, which is often knocked for bad documentation and is still fairly alpha-ish, is substantially better as far as I can tell. (R): At least as far as I'm aware, there's no good IDE for it. Again, even D, a fairly alpha-ish language with a small community, does better. In general, I also feel like MATLAB and R could be easily replaced by plain old libraries in more general-purpose langauges, if sufficiently comprehensive libraries existed. This is especially true in newer general purpose languages that include lots of features for library writers. Why do R and MATLAB seem so weird to me? Are there any other major issues that you've noticed that may make these languages come off as strange to hardcore programmers? When their use is necessary, what are some good survival tips? Edit: I'm seeing one issue from some of the answers I've gotten. I have a strong personal preference, when I analyze data, to have one script that incorporates the whole pipeline. This implies that a general purpose language needs to be used. I hate having to write a script to "clean up" the data and spit it out, then another to read it back in a completely different environment, etc. I find the friction of using MATLAB/R for some of my work and a completely different language with a completely different address space and way of thinking for the rest to be a huge source of friction. Furthermore, I know there are glue layers that exist, but they always seem to be horribly complicated and a source of friction.

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• How Do You Actually Model Data?

  Since the 1970’s Developers, Analysts and DBAs have been able to represent concepts and relations in the form of data through the use of generic symbols.  But what is data modeling?  The first time I actually heard this term I could not understand why anyone would want to display a computer on a fashion show runway. Hey, what do you expect? At that time I was a freshman in community college, and obviously this was a long time ago.  I have since had the chance to learn what data modeling truly is through using it. Data modeling is a process of breaking down information and/or requirements in to common categories called objects. Once objects start being defined then relationships start to form based on dependencies found amongst other existing objects.  Currently, there are several tools on the market that help data designer actually map out objects and their relationships through the use of symbols and lines.  These diagrams allow for designs to be review from several perspectives so that designers can ensure that they have the optimal data design for their project and that the design is flexible enough to allow for potential changes and/or extension in the future. Additionally these basic models can always be further refined to show different levels of details depending on the target audience through the use of three different types of models. Conceptual Data Model(CDM)Conceptual Data Models include all key entities and relationships giving a viewer a high level understanding of attributes. Conceptual data model are created by gathering and analyzing information from various sources pertaining to a project during the typical planning phase of a project. Logical Data Model (LDM)Logical Data Models are conceptual data models that have been expanded to include implementation details pertaining to the data that it will store. Additionally, this model typically represents an origination’s business requirements and business rules by defining various attribute data types and relationships regarding each entity. This additional information can be directly translated to the Physical Data Model which reduces the actual time need to implement it. Physical Data Model(PDMs)Physical Data Model are transformed Logical Data Models that include the necessary tables, columns, relationships, database properties for the creation of a database. This model also allows for considerations regarding performance, indexing and denormalization that are applied through database rules, data integrity. Further expanding on why we actually use models in modern application/database development can be seen in the benefits that data modeling provides for data modelers and projects themselves, Benefits of Data Modeling according to Applied Information Science Abstraction that allows data designers remove concepts and ideas form hard facts in the form of data. This gives the data designers the ability to express general concepts and/or ideas in a generic form through the use of symbols to represent data items and the relationships between the items. Transparency through the use of data models allows complex ideas to be translated in to simple symbols so that the concept can be understood by all viewpoints and limits the amount of confusion and misunderstanding. Effectiveness in regards to tuning a model for acceptable performance while maintaining affordable operational costs. In addition it allows systems to be built on a solid foundation in terms of data. I shudder at the thought of a world without data modeling, think about it? Data is everywhere in our lives. Data modeling allows for optimizing a design for performance and the reduction of duplication. If one was to design a database without data modeling then I would think that the first things to get impacted would be database performance due to poorly designed database and there would be greater chances of unnecessary data duplication that would also play in to the excessive query times because unneeded records would need to be processed. You could say that a data designer designing a database is like a box of chocolates. You will never know what kind of database you will get until after it is built.

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• Need WIF Training?

  - by Your DisplayName here!

  I spend numerous hours every month answering questions about WIF and identity in general. This made me realize that this is still quite a complicated topic once you go beyond the standard fedutil stuff. My good friend Brock and I put together a two day training course about WIF that covers everything we think is important. The course includes extensive lab material where you take standard application and apply all kinds of claims and federation techniques and technologies like WS-Federation, WS-Trust, session management, delegation, home realm discovery, multiple identity providers, Access Control Service, REST, SWT and OAuth. The lab also includes the latest version of the thinktecture identityserver and you will learn how to use and customize it. If you are looking for an open enrollment style of training, have a look here. Or contact me directly! The course outline looks as follows: Day 1 Intro to Claims-based Identity & the Windows Identity Foundation WIF introduces important concepts like conversion of security tokens and credentials to claims, claims transformation and claims-based authorization. In this module you will learn the basics of the WIF programming model and how WIF integrates into existing .NET code. Externalizing Authentication for Web Applications WIF includes support for the WS-Federation protocol. This protocol allows separating business and authentication logic into separate (distributed) applications. The authentication part is called identity provider or in more general terms - a security token service. This module looks at this scenario both from an application and identity provider point of view and walks you through the necessary concepts to centralize application login logic both using a standard product like Active Directory Federation Services as well as a custom token service using WIF’s API support. Externalizing Authentication for SOAP Services One big benefit of WIF is that it unifies the security programming model for ASP.NET and WCF. In the spirit of the preceding modules, we will have a look at how WIF integrates into the (SOAP) web service world. You will learn how to separate authentication into a separate service using the WS-Trust protocol and how WIF can simplify the WCF security model and extensibility API. Day 2 Advanced Topics:  Security Token Service Architecture, Delegation and Federation The preceding modules covered the 80/20 cases of WIF in combination with ASP.NET and WCF. In many scenarios this is just the tip of the iceberg. Especially when two business partners decide to federate, you usually have to deal with multiple token services and their implications in application design. Identity delegation is a feature that allows transporting the client identity over a chain of service invocations to make authorization decisions over multiple hops. In addition you will learn about the principal architecture of a STS, how to customize the one that comes with this training course, as well as how to build your own. Outsourcing Authentication:  Windows Azure & the Azure AppFabric Access Control Service Microsoft provides a multi-tenant security token service as part of the Azure platform cloud offering. This is an interesting product because it allows to outsource vital infrastructure services to a managed environment that guarantees uptime and scalability. Another advantage of the Access Control Service is, that it allows easy integration of both the “enterprise” protocols like WS-* as well as “web identities” like LiveID, Google or Facebook into your applications. ACS acts as a protocol bridge in this case where the application developer doesn’t need to implement all these protocols, but simply uses a service to make it happen. Claims & Federation for the Web and Mobile World Also the web & mobile world moves to a token and claims-based model. While the mechanics are almost identical, other protocols and token types are used to achieve better HTTP (REST) and JavaScript integration for in-browser applications and small footprint devices. Also patterns like how to allow third party applications to work with your data without having to disclose your credentials are important concepts in these application types. The nice thing about WIF and its powerful base APIs and abstractions is that it can shield application logic from these details while you can focus on implementing the actual application. HTH

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• How would I handle input with a Game Component?

  - by Aufziehvogel

  I am currently having problems from finding my way into the component-oriented XNA design. I read an overview over the general design pattern and googled a lot of XNA examples. However, they seem to be right on the opposite site. In the general design pattern, an object (my current player) is passed to InputComponent::update(Player). This means the class will know what to do and how this will affect the game (e.g. move person vs. scroll text in a menu). Yet, in XNA GameComponent::update(GameTime) is called automatically without a reference to the current player. The only XNA examples I found built some sort of higher-level Keyboard engine into the game component like this: class InputComponent: GameComponent { public void keyReleased(Keys); public void keyPressed(Keys); public bool keyDown(Keys); public void override update(GameTime gameTime) { // compare previous state with current state and // determine if released, pressed, down or nothing } } Some others went a bit further making it possible to use a Service Locator by a design like this: interface IInputComponent { public void downwardsMovement(Keys); public void upwardsMovement(Keys); public bool pausedGame(Keys); // determine which keys pressed and what that means // can be done for different inputs in different implementations public void override update(GameTime); } Yet, then I am wondering if it is possible to design an input class to resolve all possible situations. Like in a menu a mouse click can mean "click that button", but in game play it can mean "shoot that weapon". So if I am using such a modular design with game components for input, how much logic is to be put into the InputComponent / KeyboardComponent / GamepadComponent and where is the rest handled? What I had in mind, when I heard about Game Components and Service Locator in XNA was something like this: use Game Components to run the InputHandler automatically in the loop use Service Locator to be able to switch input at runtime (i.e. let player choose if he wants to use a gamepad or a keyboard; or which shall be player 1 and which player 2). However, now I cannot see how this can be done. First code example does not seem flexible enough, as on a game pad you could require some combination of buttons for something that is possible on keyboard with only one button or with the mouse) The second code example seems really hard to implement, because the InputComponent has to know in which context we are currently. Moreover, you could imagine your application to be multi-layered and let the key-stroke go through all layers to the bottom-layer which requires a different behaviour than the InputComponent would have guessed from the top-layer. The general design pattern with passing the Player to update() does not have a representation in XNA and I also cannot see how and where to decide which class should be passed to update(). At most time of course the player, but sometimes there could be menu items you have to or can click I see that the question in general is already dealt with here, but probably from a more elobate point-of-view. At least, I am not smart enough in game development to understand it. I am searching for a rather code-based example directly for XNA. And the answer there leaves (a noob like) me still alone in how the object that should receive the detected event is chosen. Like if I have a key-up event, should it go to the text box or to the player?

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• SQL to select random mix of rows fairly [migrated]

  - by Matt Sieker

  Here's my problem: I have a set of tables in a database populated with data from a client that contains product information. In addition to the basic product information, there is also information about the manufacturer, and categories for those products (a product can be in one or more categories). These categories are then referred to as "Product Categories", and which stores these products are available at. These tables are updated once a week from a feed from the customer. Since for our purposes, some of the product categories are the same, or closely related for our purposes, there is another level of categories called "General Categories", a general category can have one or more product categories. For the scope of these tables, here's some rough numbers: Data Tables: Products: 475,000 Manufacturers: 1300 Stores: 150 General Categories: 245 Product Categories: 500 Mapping Tables: Product Category -> Product: 655,000 Stores -> Products: 50,000,000 Now, for the actual problem: As part of our software, we need to select n random products, given a store and a general category. However, we also need to ensure a good mix of manufacturers, as in some categories, a single manufacturer dominates the results, and selecting rows at random causes the results to strongly favor that manufacturer. The solution that is currently in place, works for most cases, involves selecting all of the rows that match the store and category criteria, partition them on manufacturer, and include their row number from within their partition, then select from that where the row number for that manufacturer is less than n, and use ROWCOUNT to clamp the total rows returned to n. This query looks something like this: SET ROWCOUNT 6 select p.Id, GeneralCategory_Id, Product_Id, ISNULL(m.DisplayName, m.Name) AS Vendor, MSRP, MemberPrice, FamilyImageName from (select p.Id, gc.Id GeneralCategory_Id, p.Id Product_Id, ctp.Store_id, Manufacturer_id, ROW_NUMBER() OVER (PARTITION BY Manufacturer_id ORDER BY NEWID()) AS 'VendorOrder', MSRP, MemberPrice, FamilyImageName from GeneralCategory gc inner join GeneralCategoriesToProductCategories gctpc ON gc.Id=gctpc.GeneralCategory_Id inner join ProductCategoryToProduct pctp on gctpc.ProductCategory_Id = pctp.ProductCategory_Id inner join Product p on p.Id = pctp.Product_Id inner join StoreToProduct ctp on p.Id = ctp.Product_id where gc.Id = @GeneralCategory and ctp.Store_id=@StoreId and p.Active=1 and p.MemberPrice >0) p inner join Manufacturer m on m.Id = p.Manufacturer_id where VendorOrder <=6 order by NEWID() SET ROWCOUNT 0 (I've tried to somewhat format it to make it cleaner, but I don't think it really helps) Running this query with an execution plan shows that for the majority of these tables, it's doing a Clustered Index Seek. There are two operations that take up roughly 90% of the time: Index Seek (Nonclustered) on StoreToProduct: 17%. This table just contains the key of the store, and the key of the product. It seems that NHibernate decided not to make a composite key when making this table, but I'm not concerned about this at this point, as compared to the other seek... Clustered Index Seek on Product: 69%. I really have no clue how I could make this one more performant. On categories without a lot of products, performance is acceptable (<50ms), however larger categories can take a few hundred ms, with the largest category taking 3s (which has about 170k products). It seems I have two ways to go from this point: Somehow optimize the existing query and table indices to lower the query time. As almost every expensive operation is already a clustered index scan, I don't know what could be done there. The inner query could be tuned to not return all of the possible rows for that category, but I am unsure how to do this, and maintain the requirements (random products, with a good mix of manufacturers) Denormalize this data for the purpose of this query when doing the once a week import. However, I am unsure how to do this and maintain the requirements. Does anyone have any input on either of these items?

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• ArgumentError: Error #2004: One of the parameters is invalid.

  - by Florian

  I got the following stack trace while running a piece of code in my flex application: ArgumentError: Error #2004: One of the parameters is invalid. at ObjectOutput/writeObject() at mx.collections::ArrayList/writeExternal()[C:\autobuild\galaga\frameworks\projects\framework\src\mx\collections\ArrayList.as:470] at mx.collections::ArrayCollection/writeExternal()[C:\autobuild\galaga\frameworks\projects\framework\src\mx\collections\ArrayCollection.as:144] at flash.utils::ByteArray/writeObject() at mx.utils::ObjectUtil$/copy()[C:\autobuild\galaga\frameworks\projects\framework\src\mx\utils\ObjectUtil.as:100] at components::SettingsHandler/saveOpenNodes()[C:\workspaces\Intranets\UniqueInbox\flex_src\components\SettingsHandler.as:153] at components::soapjira/getIssuesByFilters()[C:\workspaces\Intranets\UniqueInbox\flex_src\components\soapjira.as:295] at components.tabs::JiraAllActions/loadData()[C:\workspaces\Intranets\UniqueInbox\flex_src\components\tabs\JiraAllActions.mxml:193] at components::SettingsHandler/settingsClosed()[C:\workspaces\Intranets\UniqueInbox\flex_src\components\SettingsHandler.as:114] at flash.events::EventDispatcher/dispatchEventFunction() at flash.events::EventDispatcher/dispatchEvent() at mx.core::UIComponent/dispatchEvent()[C:\autobuild\galaga\frameworks\projects\framework\src\mx\core\UIComponent.as:9408] at components.general::JiraSettings/closeSettings()[C:\workspaces\Intranets\UniqueInbox\flex_src\components\general\JiraSettings.mxml:58] at components.general::JiraSettings/__save_click()[C:\workspaces\Intranets\UniqueInbox\flex_src\components\general\JiraSettings.mxml:107] That stack comes up when running the following line (SettingsHandler.as:153): var tmp:Object = parentComponent.dataGrid.dataProvider.openNodes; I am actually copying the open nodes of a datagrid's provider. Has been working until now and just started going wrong, no idea what I have changed that could interfere with this. On debug mode, I see that openNodes is accessible and contains the open nodes, as expected. Doing tmp:Object = parentComponent.dataGrid.dataProvider.openNodes works, but not with ObjectUtil. (parentComponent is the reference to the component which contains the DG).

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• Service Oriented Architecture & Domain-Driven Design

  - by Michael

  I've always developed code in a SOA type of way. This year I've been trying to do more DDD but I keep getting the feeling that I'm not getting it. At work our systems are load balanced and designed not to have state. The architecture is: Website ===Physical Layer== Main Service ==Physical Layer== Server 1/Service 2/Service 3/Service 4 Only Server 1,Service 2,Service 3 and Service 4 can talk to the database and the Main Service calls the correct service based on products ordered. Every physical layer is load balanced too. Now when I develop a new service, I try to think DDD in that service even though it doesn't really feel like it fits. I use good DDD principles like entities, value types, repositories, aggregates, factories and etc. I've even tried using ORM's but they just don't seem like they fit in a stateless architecture. I know there are ways around it, for example use IStatelessSession instead of ISession with NHibernate. However, ORM just feel like they don't fit in a stateless architecture. I've noticed I really only use some of the concepts and patterns DDD has taught me but the overall architecture is still SOA. I am starting to think DDD doesn't fit in large systems but I do think some of the patterns and concepts do fit in large systems. Like I said, maybe I'm just not grasping DDD or maybe I'm over analyzing my designs? Maybe by using the patterns and concepts DDD has taught me I am using DDD? Not sure if there is really a question to this post but more of thoughts I've had when trying to figure out where DDD fits in overall systems and how scalable it truly is. The truth is, I don't think I really even know what DDD is?

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• How to get a handle on all this middleware?

  - by jkohlhepp

  My organization has recently been wrestling the question of whether we should be incorporating different middleware products / concepts into our applications. Products we are looking at are things like Pegasystems, Oracle BPM / BPEL, BizTalk, Fair Isaac Blaze, etc., etc., etc. But I'm having a hard time getting a handle on all this. Before I go forward with evaluating the usefulness (positive or negative) of these different products I'm trying to get an understanding of all the different concepts in this space. I'm overwhelmed with an alphabet soup of BPM, ESB, SOA, CEP, WF, BRE, ERP, etc. Some products seem to cover one or more of those aspects, others focus on doing one. The terms all seem very ambiguous and conflated with each other. Is there a good resource out there to get a handle on all these different middleware concepts / patterns? A book? A website? An article that sums it up well? Bonus points if there is a resource that maps the various popular products into which pattern(s) they address. Thanks, ~ Justin

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• About Data Objects and DAO Design when using Hibernate

  - by X. Ma

  I'm hesitating between two designs of a database project using Hibernate. Design #1. (1) Create a general data provider interface, including a set of DAO interfaces and general data container classes. It hides the underneath implementation. A data provider implementation could access data in database, or an XML file, or a service, or something else. The user of a data provider does not to know about it. (2) Create a database library with Hibernate. This library implements the data provider interface in (1). The bad thing about Design #1 is that in order to hide the implementation details, I need to create two sets of data container classes. One in the general data provider interface - let's call them DPI-Objects, the other set is used in the database library, exclusively for entity/attribute mapping in Hibernate - let's call them H-Objects. In the DAO implementation, I need to read data from database to create H-Objects (via Hibernate) and then convert H-Objects into DPI-Objects. Design #2. Do not create a general data provider interface. Expose H-Objects directly to components that use the database lib. So the user of the database library needs to be aware of Hibernate. I like design #1 more, but I don't want to create two sets of data container classes. Is that the right way to hide H-Objects and other Hibernate implementation details from the user who uses the database-based data provider? Are there any drawbacks of Design #2? I will not implement other data provider in the new future, so should I just forget about the data provider interface and use Design #2? What do you think about this? Thanks for your time!

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• How to configure database connection securely

  - by chiccodoro

  Similar but not the same: How to securely store database connection details Securely connecting to database within a application Hi all, I have a C# WinForms application connecting to a database server. The database connection string, including a generic user/pass, is placed in a NHibernate configuration file, which lies in the same directory as the exe file. Now I have this issue: The user that runs the application should not get to know the username/password of the general database user because I don't want him to rummage around in the database directly. Alternatively I could hardcode the connection string, which is bad because the administrator must be able to change it if the database is moved or if he wants to switch between dev/test/prod environments. So long I've found three possibilities: The first referenced question was generally answered by making the file only readable for the user that runs the application. But that's not not enough in my case (the user running the application is a person. The database user/pass are general and shouldn't even be accessible by the person.) The first answer additionally proposed to encrypt the connection data before writing it to the file. With this approach, the administrator is not able anymore to configure the connection string because he cannot encrypt it by hand. The second referenced question provides an approach for this very scenario but it seems very complicated. My questions to you: This is a very general issue, so isn't there any general "how-to-do-it" way, somehow a "design pattern"? Is there some support in .NET's config infrastructure? (optional, maybe out of scope) Can I combine that easily with the NHibernate configuration mechanism?

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• Should I Teach My Son Programming? What approaches should I take? [closed]

  - by DaveDev

  I was wondering if it's a good idea to teach object oriented programming to my son? I was never really good at math as a kid, but I think since I've started programming it's given me a greater ability to understand math by being better able to visualise relationships between abstract models. I thought it might give him a better advantage in learning & applying logical & mathematical concepts throughout his life if he was able to take advantage of the tools available to programmers. what would be the best programming fields, techniques and/or concepts? What approach should I take? what concepts should I avoid? what fields of mathematics would he find this benfits him most? He's only 2 now so it wouldn't be for another few years before I do this, (and even at that, only from a very high level point of view). I thought I'd put it to the programming community and see what you guys thought? Possible Duplicate: What are some recommended programming resources for pre-teens?

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• Best Practices - which domain types should be used to run applications

  - by jsavit

  This post is one of a series of "best practices" notes for Oracle VM Server for SPARC (formerly named Logical Domains) One question that frequently comes up is "which types of domain should I use to run applications?" There used to be a simple answer in most cases: "only run applications in guest domains", but enhancements to T-series servers, Oracle VM Server for SPARC and the advent of SPARC SuperCluster have made this question more interesting and worth qualifying differently. This article reviews the relevant concepts and provides suggestions on where to deploy applications in a logical domains environment. Review: division of labor and types of domain Oracle VM Server for SPARC offloads many functions from the hypervisor to domains (also called virtual machines). This is a modern alternative to using a "thick" hypervisor that provides all virtualization functions, as in traditional VM designs, This permits a simpler hypervisor design, which enhances reliability, and security. It also reduces single points of failure by assigning responsibilities to multiple system components, which further improves reliability and security. In this architecture, management and I/O functionality are provided within domains. Oracle VM Server for SPARC does this by defining the following types of domain, each with their own roles: Control domain - management control point for the server, used to configure domains and manage resources. It is the first domain to boot on a power-up, is an I/O domain, and is usually a service domain as well. I/O domain - has been assigned physical I/O devices: a PCIe root complex, a PCI device, or a SR-IOV (single-root I/O Virtualization) function. It has native performance and functionality for the devices it owns, unmediated by any virtualization layer. Service domain - provides virtual network and disk devices to guest domains. Guest domain - a domain whose devices are all virtual rather than physical: virtual network and disk devices provided by one or more service domains. In common practice, this is where applications are run. Typical deployment A service domain is generally also an I/O domain: otherwise it wouldn't have access to physical device "backends" to offer to its clients. Similarly, an I/O domain is also typically a service domain in order to leverage the available PCI busses. Control domains must be I/O domains, because they boot up first on the server and require physical I/O. It's typical for the control domain to also be a service domain too so it doesn't "waste" the I/O resources it uses. A simple configuration consists of a control domain, which is also the one I/O and service domain, and some number of guest domains using virtual I/O. In production, customers typically use multiple domains with I/O and service roles to eliminate single points of failure: guest domains have virtual disk and virtual devices provisioned from more than one service domain, so failure of a service domain or I/O path or device doesn't result in an application outage. This is also used for "rolling upgrades" in which service domains are upgraded one at a time while their guests continue to operate without disruption. (It should be noted that resiliency to I/O device failures can also be provided by the single control domain, using multi-path I/O) In this type of deployment, control, I/O, and service domains are used for virtualization infrastructure, while applications run in guest domains. Changing application deployment patterns The above model has been widely and successfully used, but more configuration options are available now. Servers got bigger than the original T2000 class machines with 2 I/O busses, so there is more I/O capacity that can be used for applications. Increased T-series server capacity made it attractive to run more vertical applications, such as databases, with higher resource requirements than the "light" applications originally seen. This made it attractive to run applications in I/O domains so they could get bare-metal native I/O performance. This is leveraged by the SPARC SuperCluster engineered system, announced a year ago at Oracle OpenWorld. In SPARC SuperCluster, I/O domains are used for high performance applications, with native I/O performance for disk and network and optimized access to the Infiniband fabric. Another technical enhancement is the introduction of Direct I/O (DIO) and Single Root I/O Virtualization (SR-IOV), which make it possible to give domains direct connections and native I/O performance for selected I/O devices. A domain with either a DIO or SR-IOV device is an I/O domain. In summary: not all I/O domains own PCI complexes, and there are increasingly more I/O domains that are not service domains. They use their I/O connectivity for performance for their own applications. However, there are some limitations and considerations: at this time, a domain using physical I/O cannot be live-migrated to another server. There is also a need to plan for security and introducing unneeded dependencies: if an I/O domain is also a service domain providing virtual I/O go guests, it has the ability to affect the correct operation of its client guest domains. This is even more relevant for the control domain. where the ldm has to be protected from unauthorized (or even mistaken) use that would affect other domains. As a general rule, running applications in the service domain or the control domain should be avoided. To recap: Guest domains with virtual I/O still provide the greatest operational flexibility, including features like live migration. I/O domains can be used for applications with high performance requirements. This is used to great effect in SPARC SuperCluster and in general T4 deployments. Direct I/O (DIO) and Single Root I/O Virtualization (SR-IOV) make this more attractive by giving direct I/O access to more domains. Service domains should in general not be used for applications, because compromised security in the domain, or an outage, can affect other domains that depend on it. This concern can be mitigated by providing guests' their virtual I/O from more than one service domain, so an interruption of service in the service domain does not cause an application outage. The control domain should in general not be used to run applications, for the same reason. SPARC SuperCluster use the control domain for applications, but it is an exception: it's not a general purpose environment; it's an engineered system with specifically configured applications and optimization for optimal performance. These are recommended "best practices" based on conversations with a number of Oracle architects. Keep in mind that "one size does not fit all", so you should evaluate these practices in the context of your own requirements. Summary Higher capacity T-series servers have made it more attractive to use them for applications with high resource requirements. New deployment models permit native I/O performance for demanding applications by running them in I/O domains with direct access to their devices. This is leveraged in SPARC SuperCluster, and can be leveraged in T-series servers to provision high-performance applications running in domains. Carefully planned, this can be used to provide higher performance for critical applications.

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• Any reason not to disable Windows kernel paging?

  - by Nathaniel

  So I'm planning on eventually going to 2 GB (mobo max) RAM from 1 GB, and I want to disable kernel paging once I do, because I've heard it can give a performance boost (and that I believe). Any reason not to do it or any general thoughts about it? Edit: for clarification, this is not disabling general RAM paging. This is disabling having kernel memory paged (or at least parts of it, as Charlls noted).

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• Any reason not to disable Windows kernel paging?

  - by Nathaniel

  So I'm planning on eventually going to 2 GB (mobo max) RAM from 1 GB, and I want to disable kernel paging once I do, because I've heard it can give a performance boost (and that I believe). Any reason not to do it or any general thoughts about it? Edit: for clarification, this is not disabling general RAM paging. This is disabling having kernel memory paged (or at least parts of it, as Charlls noted).

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• Are these mySQL user settings vulnerable?

  - by Kavon Farvardin

  I'm using myphpadmin to manage the databases and I'm new to SQL in general. Am I suppose to keep an open anonymous user on localhost so things like drupal can access mySQL? It seems like having a non-passworded root on my server's hostname is retarded but I don't know what I'm doing with this in general. The user who's name starts with a b is the one I use to login and do things like make a database.

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• What's the correct term for this network connection?

  - by Preet Sangha

  What is the correct general term for the network connection on mobile devices that can connect to networks via telecoms links? Question asked "my device is not connecting to my local web server here". My response "Are you using Wifi or XXXX to to connect?" Where XXXX is the network connection through the phone system - e.g. 3g, gprs, etc... What is the general term encompassing term for XXXX please?

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• When does /tmp get cleared?

  - by John Lawrence Aspden

  I'm taking to putting various files in /tmp, and I wondered what the rules on deleting them are? I'm imagining it's different for different distributions, and I'm particularly interested in Ubuntu and Fedora desktop versions. But a nice general way of finding out would be a great thing. Even better would be a nice general way of controlling it! (Something like 'every day at 3 in the morning, delete any /tmp files older than 60 days, but don't clear the directory on reboot')

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• Task-dedicated computers for the household?

  - by Matias Nino

  This question is to generate ideas for task-dedicated computers in a household. Here's mine: Personal Desktop - Gaming, working, office productivity, entertainment, CD/DVD burning General Server - backups, application hosting, mail server, file server, VM server, torrent seeding Personal Laptop - software development, mobile computing Media Center PC - Digital media playback, media file server, Gaming Photo PC - Digital photo management/archival. Nightstand Netbook - Bedtime surfing/reading Spare Laptop - general household use

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• Routing Essentials

  - by zharvey

  I'm a programmer trying to fill a big hole in my understanding of networking basics. I've been reading a good book (Networking Bible by Sosinki) but I have been finding that there is a lot of "assumed" information contained, where terms/concepts are thrown at the reader without a proper introduction to them. I understand that a "route" is a path through a network. But I am struggling with visualizing some routing-based concepts. Namely: How do routes actually manifest themselves in the hardware? Are they just a list of IP addresses that get computed at the network layer, and then executed by the transport? What kind of data exists in a so-caleld routing table? Is a routing-table just the mechanism for holding these lists of IP address (read above)? What are the performance pros/cons for having a static route, as opposed to a dynamic route?

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• Storing data, cost/gigabyte

  - by Micaela

  Can anyone give me a general estimate for what web-hosts charge for data storage ($/gigabyte)? A shared-webhosting service is what I'm referring to. I have been trying to compare the price for storage offered by business process automation SaaS and now I'm looking more general.

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• Foreign Key constraint violation when persisting a many-to-one class

  - by tieTYT

  I'm getting an error when trying to persist a many to one entity: Internal Exception: org.postgresql.util.PSQLException: ERROR: insert or update on table "concept" violates foreign key constraint "concept_concept_class_fk" Detail: Key (concept_class_id)=(Concept) is not present in table "concept_class". Error Code: 0 Call: INSERT INTO concept (concept_key, description, label, code, concept_class_id) VALUES (?, ?, ?, ?, ?) bind = [27, description_1, label_1, code_1, Concept] Query: InsertObjectQuery(com.mirth.results.entities.Concept[conceptKey=27]) at com.sun.ejb.containers.BaseContainer.checkExceptionClientTx(BaseContainer.java:3728) at com.sun.ejb.containers.BaseContainer.postInvokeTx(BaseContainer.java:3576) at com.sun.ejb.containers.BaseContainer.postInvoke(BaseContainer.java:1354) ... 101 more Here is the method that tries to persist it. I've put a comment where the line is: @Override public void loadConcept(String metaDataFilePath, String dataFilePath) throws Exception { try { ConceptClassMetaData conceptClassMetaData = (ConceptClassMetaData) ModelSerializer.getInstance().fromXML(FileUtils.readFileToString(new File(metaDataFilePath), "UTF8")); em.executeNativeQuery(conceptClassMetaData.getCreateStatement()); ConceptClassRow conceptClassRow = conceptClassMetaData.getConceptClassRow(); ConceptClass conceptClass = em.findByPrimaryKey(ConceptClass.class, conceptClassRow.getId()); if (conceptClass == null) { conceptClass = new ConceptClass(conceptClassRow.getId()); } conceptClass.setLabel(conceptClassRow.getLabel()); conceptClass.setOid(conceptClassRow.getOid()); conceptClass.setDescription(conceptClassRow.getDescription()); conceptClass = em.merge(conceptClass); DataParser dataParser = new DataParser(conceptClassMetaData, dataFilePath); for (ConceptModel conceptModel : dataParser.getConceptRows()) { ConceptFilter<Concept> filter = new ConceptFilter<Concept>(Concept.class); filter.setCode(conceptModel.getCode()); filter.setConceptClass(conceptClass.getLabel()); List<Concept> concepts = em.findAllByFilter(filter); Concept concept = new Concept(); if (concepts != null && !concepts.isEmpty()) { concept = concepts.get(0); } concept.setCode(conceptModel.getCode()); concept.setDescription(conceptModel.getDescription()); concept.setLabel(conceptModel.getLabel()); concept.setConceptClass(conceptClass); concept = em.merge(concept); //THIS LINE CAUSES THE ERROR! } } catch (Exception e) { e.printStackTrace(); throw e; } } ... Here are how the two entities are defined: @Entity @Table(name = "concept") @Inheritance(strategy=InheritanceType.JOINED) @DiscriminatorColumn(name="concept_class_id", discriminatorType=DiscriminatorType.STRING) public class Concept extends KanaEntity { @Id @Basic(optional = false) @Column(name = "concept_key") protected Integer conceptKey; @Basic(optional = false) @Column(name = "code") private String code; @Basic(optional = false) @Column(name = "label") private String label; @Column(name = "description") private String description; @JoinColumn(name = "concept_class_id", referencedColumnName = "id") @ManyToOne private ConceptClass conceptClass; ... @Entity @Table(name = "concept_class") public class ConceptClass extends KanaEntity { @Id @Basic(optional = false) @Column(name = "id") private String id; @Basic(optional = false) @Column(name = "label") private String label; @Column(name = "oid") private String oid; @Column(name = "description") private String description; .... And also, what's important is the sql that's being generated: INSERT INTO concept_class (id, oid, description, label) VALUES (?, ?, ?, ?) bind = [LOINC_TEST, 2.16.212.31.231.54, This is a meta data file for LOINC_TEST, loinc_test] INSERT INTO concept (concept_key, description, label, code, concept_class_id) VALUES (?, ?, ?, ?, ?) bind = [27, description_1, label_1, code_1, Concept] The reason this is failing is obvious: It's inserting the word Concept for the concept_class_id. It should be inserting the word LOINC_TEST. I can't figure out why it's using this word. I've used the debugger to look at the Concept and the ConceptClass instance and neither of them contain this word. I'm using eclipselink. Does anyone know why this is happening?

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• Foreign Key constraint when persisting a many-to-one class

  - by tieTYT

  I'm getting an error when trying to persist a many to one entity: Internal Exception: org.postgresql.util.PSQLException: ERROR: insert or update on table "concept" violates foreign key constraint "concept_concept_class_fk" Detail: Key (concept_class_id)=(Concept) is not present in table "concept_class". Error Code: 0 Call: INSERT INTO concept (concept_key, description, label, code, concept_class_id) VALUES (?, ?, ?, ?, ?) bind = [27, description_1, label_1, code_1, Concept] Query: InsertObjectQuery(com.mirth.results.entities.Concept[conceptKey=27]) at com.sun.ejb.containers.BaseContainer.checkExceptionClientTx(BaseContainer.java:3728) at com.sun.ejb.containers.BaseContainer.postInvokeTx(BaseContainer.java:3576) at com.sun.ejb.containers.BaseContainer.postInvoke(BaseContainer.java:1354) ... 101 more Here is the method that tries to persist it. I've put a comment where the line is: @Override public void loadConcept(String metaDataFilePath, String dataFilePath) throws Exception { try { ConceptClassMetaData conceptClassMetaData = (ConceptClassMetaData) ModelSerializer.getInstance().fromXML(FileUtils.readFileToString(new File(metaDataFilePath), "UTF8")); em.executeNativeQuery(conceptClassMetaData.getCreateStatement()); ConceptClassRow conceptClassRow = conceptClassMetaData.getConceptClassRow(); ConceptClass conceptClass = em.findByPrimaryKey(ConceptClass.class, conceptClassRow.getId()); if (conceptClass == null) { conceptClass = new ConceptClass(conceptClassRow.getId()); } conceptClass.setLabel(conceptClassRow.getLabel()); conceptClass.setOid(conceptClassRow.getOid()); conceptClass.setDescription(conceptClassRow.getDescription()); conceptClass = em.merge(conceptClass); DataParser dataParser = new DataParser(conceptClassMetaData, dataFilePath); for (ConceptModel conceptModel : dataParser.getConceptRows()) { ConceptFilter<Concept> filter = new ConceptFilter<Concept>(Concept.class); filter.setCode(conceptModel.getCode()); filter.setConceptClass(conceptClass.getLabel()); List<Concept> concepts = em.findAllByFilter(filter); Concept concept = new Concept(); if (concepts != null && !concepts.isEmpty()) { concept = concepts.get(0); } concept.setCode(conceptModel.getCode()); concept.setDescription(conceptModel.getDescription()); concept.setLabel(conceptModel.getLabel()); concept.setConceptClass(conceptClass); concept = em.merge(concept); //THIS LINE CAUSES THE ERROR! } } catch (Exception e) { e.printStackTrace(); throw e; } } ... Here are how the two entities are defined: @Entity @Table(name = "concept") @Inheritance(strategy=InheritanceType.JOINED) @DiscriminatorColumn(name="concept_class_id", discriminatorType=DiscriminatorType.STRING) public class Concept extends KanaEntity { @Id @Basic(optional = false) @Column(name = "concept_key") protected Integer conceptKey; @Basic(optional = false) @Column(name = "code") private String code; @Basic(optional = false) @Column(name = "label") private String label; @Column(name = "description") private String description; @JoinColumn(name = "concept_class_id", referencedColumnName = "id") @ManyToOne private ConceptClass conceptClass; ... @Entity @Table(name = "concept_class") public class ConceptClass extends KanaEntity { @Id @Basic(optional = false) @Column(name = "id") private String id; @Basic(optional = false) @Column(name = "label") private String label; @Column(name = "oid") private String oid; @Column(name = "description") private String description; .... And also, what's important is the sql that's being generated: INSERT INTO concept_class (id, oid, description, label) VALUES (?, ?, ?, ?) bind = [LOINC_TEST, 2.16.212.31.231.54, This is a meta data file for LOINC_TEST, loinc_test] INSERT INTO concept (concept_key, description, label, code, concept_class_id) VALUES (?, ?, ?, ?, ?) bind = [27, description_1, label_1, code_1, Concept] The reason this is failing is obvious: It's inserting the word Concept for the concept_class_id. It should be inserting the word LOINC_TEST. I can't figure out why it's using this word. I've used the debugger to look at the Concept and the ConceptClass instance and neither of them contain this word. I'm using eclipselink. Does anyone know why this is happening?

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• Book Review: &ldquo;Inside Microsoft SQL Server 2008: T-SQL Querying&rdquo; by Itzik Ben-Gan et al

  - by Sam Abraham

  In the past few weeks, I have been reading “Inside Microsoft SQL Server 2008: T-SQL Querying” by Itzik Ben-Gan et al. In the next few lines, I will be providing a quick book review having finished reading this valuable resource on SQL Server 2008. In this book, the authors have targeted most of the common as well as advanced T-SQL Querying scenarios that one would use for development on a SQL Server database. Book content covered sufficient theory and practice to empower its readers to systematically write better performance-tuned queries. Chapter one introduced a quick refresher of the basics of query processing. Chapters 2 and 3 followed with a thorough coverage of applicable relational algebra concepts which set a good stage for chapter 4 to dive deep into query tuning. Chapter 4 has been my favorite chapter of the book as it provided nice illustrations of the internals of indexes, waits, statistics and query plans. I particularly appreciated the thorough explanation of execution plans which helped clarify some areas I may have not paid particular attention to in the past. The book continues to focus on SQL operators tackling a few in each chapter and covering their internal workings and the best practices to follow when used. Figures and illustrations have been particularly helpful in grasping advanced concepts covered therein. In conclusion, Inside Microsoft SQL Server 2008: T-SQL Querying provided me with 750+ pages of focused, advanced and practical knowledge that has added a few tips and tricks to my arsenal of query tuning strategies. Many thanks to the O’Reilly User Group Program and its support of our West Palm Beach Developers’ Group. --Sam Abraham

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• Database version control resources

  - by Wes McClure

  In the process of creating my own DB VCS tool tsqlmigrations.codeplex.com I ran into several good resources to help guide me along the way in reviewing existing offerings and in concepts that would be needed in a good DB VCS.  This is my list of helpful links that others can use to understand some of the concepts and some of the tools in existence.  In the next few posts I will try to explain how I used these to create TSqlMigrations.   Blogs entries Three rules for database work - K. Scott Allen http://odetocode.com/blogs/scott/archive/2008/01/30/three-rules-for-database-work.aspx Versioning databases - the baseline http://odetocode.com/blogs/scott/archive/2008/01/31/versioning-databases-the-baseline.aspx Versioning databases - change scripts http://odetocode.com/blogs/scott/archive/2008/02/02/versioning-databases-change-scripts.aspx Versioning databases - views, stored procedures and the like http://odetocode.com/blogs/scott/archive/2008/02/02/versioning-databases-views-stored-procedures-and-the-like.aspx Versioning databases - branching and merging http://odetocode.com/blogs/scott/archive/2008/02/03/versioning-databases-branching-and-merging.aspx Evolutionary Database Design - Martin Fowler http://martinfowler.com/articles/evodb.html Are database migration frameworks worth the effort? - Good challenges http://www.ridgway.co.za/archive/2009/01/03/are-database-migration-frameworks-worth-the-effort.aspx Continuous Integration (in general) http://martinfowler.com/articles/continuousIntegration.html http://martinfowler.com/articles/originalContinuousIntegration.html Is Your Database Under Version Control? http://www.codinghorror.com/blog/archives/000743.html 11 Tools for Database Versioning http://secretgeek.net/dbcontrol.asp How to do database source control and builds http://mikehadlow.blogspot.com/2006/09/how-to-do-database-source-control-and.html .Net Database Migration Tool Roundup http://flux88.com/blog/net-database-migration-tool-roundup/ Books Book Description Refactoring Databases: Evolutionary Database Design Martin Fowler signature series on refactoring databases. Book site: http://databaserefactoring.com/ Recipes for Continuous Database Integration: Evolutionary Database Development (Digital Short Cut) A good question/answer layout of common problems and solutions with database version control. http://www.informit.com/store/product.aspx?isbn=032150206X

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