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• Visual Studio 2010 ADO.NET Data Model vs Linq to SQL

  - by LaGrad

  What's the difference between the two? They seem to have the same functionality at first glance. Which one has faster performance which one is easier to use?

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• ADO.NET Data model and JSON

  - by ognjenb

  public ActionResult Example() { var q = from i in proba.name select i; return View(); } How with this data make Json data and put them to table (on some View - no strongly typed)

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• Rails 2.3 using another model's named_scope or alternative

  - by mustafi

  Hi Let's say I have two models like so: class Comment < ActiveRecord::Base belongs_to :user named_scope :about_x :conditions => "comments.text like '%x%')" end class User < ActiveRecord::Base has_many :comments end I would like to use the models so that I can return all the users and all comments with text like '%x%' all_user_comments_about_x = User.comments.about_x How to proceed? Thank you

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• Unable to update the EntitySet because it has a DefiningQuery and no &lt;UpdateFunction&gt; element

  - by Harish Ranganathan

  When working with ADO.NET Entity Data Model, its often common that we generate entity schema for more than a single table from our Database.  With Entity Model generation automated with Visual Studio support, it becomes even tempting to create and work entity models to achieve an object mapping relationship. One of the errors that you might hit while trying to update an entity set either programmatically using context.SaveChanges or while using the automatic insert/update code generated by GridView etc., is “Unable to update the EntitySet <EntityName> because it has a DefiningQuery and no <UpdateFunction> element exists in the <ModificationFunctionMapping> element to support the current operation” While the description is pretty lengthy, the immediate thing that would come to our mind is to open our the entity model generated code and see if you can update it accordingly. However, the first thing to check if that, if the Entity Set is generated from a table, whether the Table defines a primary key.  Most of the times, we create tables with primary keys.  But some reference tables and tables which don’t have a primary key cannot be updated using the context of Entity and hence it would throw this error.  Unless it is a View, in which case, the default model is read-only, most of the times the above error occurs since there is no primary key defined in the table. There are other reasons why this error could popup which I am not going into for the sake of simplicity of the post.  If you find something new, please feel free to share it in comments. Hope this helps. Cheers !!!

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• Simultaneous AI in turn based games

  - by Eduard Strehlau

  I want to hack together a roguelike. Now I thought about entity and world representation and got to a quite big problem. If you want all the AI to act simultaneously you would normally(in cellular automa for examble) just copy the cell buffer and let all action of indiviual cells depend on the copy. Actions which are not valid anymore after some cell before the cell you are currently operating on changed the original enviourment(blocking the path) are just ignored or reapplied with the "current"(between turns) environment. After all cells have acted you copy the current map to the buffer again. Now for an environment with complex AI and big(datawise) entities the copying would take too long. So I thought you could put every action and entity makes into a que(make no changes to the environment) and execute the whole que after everyone took their move. Every interaction on this que are realy interacting entities, so if a entity tries to attack another entity it sends a message to it, the consequences of the attack would be visible next turn, either by just examining the entity or asking the entity for data. This would remove problems like what happens if an entity dies middle in the cue but got actions or is messaged later on(all messages would go to null, and the messages from the entity would either just be sent or deleted(haven't decided yet) But what would happen if a monster spawns a fireball which by itself tracks the player(in the same turn). Should I add the fireball to the enviourment beforehand, so make a change to the environment before executing the action list or just add the ball to the "need updated" list as a special case so it doesn't exist in the environment and still operates on it, spawing after evaluating the action list? Are there any solutions or papers on this subject which I can take a look at? EDIT: I don't need information on writing a roguelike I need information on turn based ai in respective to a complex enviourment.

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• [EF + Oracle]Object Context

  - by JTorrecilla

  Prologue After EF episodes I and II, we are going to see the Object Context. What is Object Context? It is a class which manages the DB connection, and the different Entities of our model. When Visual Studio creates the EF model, like I explain previously, also generates a Class that extends ObjectContext. ObjectContext provides: - DB connection - Add, update and delete functions. - Object Sets of Entities. - State of Pending Changes. This class will give a function, for each Entity, like  Esta clase va a contar con una función, para cada entidad, del tipo “AddTo{ENTITY}({Entity_Type } value)”, which are going to add a Entity to the related ObjectSet. In addition, it has a property, for each Entity, like “ObjectSet<TEntity> Entity”, does will keep the related record set. It will be filled with the CreateObjectSet<TEntity> function of Base class (ObjectContext). What is an ObjectSet? It is a class that allows us to manage the Entity Set from a Type. It inherits from: · ObjectQuery<TEntity> · IObjectSet<TEntity> · IQueryAble<TEntity · IEnumerable<TEntity · IQueryAble · IEnumerable An ObjectSet is a class property that allows query, insert, delete and update records from a determinate Entity. In following chapters we will see how to query Entities. LazyLoadingEnabled A very important property of the Context is “LazyLoadingEnabled”. This Boolean property lets indicate if the data loading is lazy, in other words, the Object will not be created and query until not be needed. Finally In this post we have seen what the VS generated context is, some of the characteristics, and where to see Entity data. In next chapters we will see, CRUD operations, and how to query ObjectSets.

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• Acr.ExtDirect &ndash; Part 1 &ndash; Method Resolvers

  - by Allan Ritchie

  One of the most important things of any open source libraries in my opinion is to be as open as possible while avoiding having your library become invasive to your code/business model design.  I personally could never stand marking my business and/or data access code with attributes everywhere.  XML also isn’t really a fav with too many people these days since it comes with a startup performance hit and requires runtime compiling.  I find that there is a whole ton of communication libraries out there currently requiring this (ie. WCF, RIA, etc).  Even though Acr.ExtDirect comes with its own set of attributes, you can piggy-back the [ServiceContract] & [OperationContract] attributes from WCF if you choose.  It goes beyond that though, there are 2 others “out-of-the-box” implementations – Convention based & XML Configuration.    Convention – I don’t actually recommend using this one since it opens up all of your public instance methods to remote execution calls. XML Configuration – This isn’t so bad but requires you enter all of your methods and there operation types into the Castle XML configuration & as I said earlier, XML isn’t the fav these days.   So what are your options if you don’t like attributes, convention, or XML Configuration?  Well, Acr.ExtDirect has its own extension base to give the API a list of methods and components to make available for remote execution.  1: public interface IDirectMethodResolver { 2:   3: bool IsServiceType(ComponentModel model, Type type); 4: string GetNamespace(ComponentModel model); 5: string[] GetDirectMethodNames(ComponentModel model); 6: DirectMethodType GetMethodType(ComponentModel model, MethodInfo method); 7: }   Now to implement our own method resolver:   1: public class TestResolver : IDirectMethodResolver { 2:   3: #region IDirectMethodResolver Members 4:   5: /// <summary> 6: /// Determine if you are calling a service 7: /// </summary> 8: /// <param name="model"></param> 9: /// <param name="type"></param> 10: /// <returns></returns> 11: public bool IsServiceType(ComponentModel model, Type type) { 12: return (type.Namespace == "MyBLL.Data"); 13: } 14:   15: /// <summary> 16: /// Return the calling name for the client side 17: /// </summary> 18: /// <param name="model"></param> 19: /// <returns></returns> 20: public string GetNamespace(ComponentModel model) { 21: return model.Name; 22: } 23:   24: public string[] GetDirectMethodNames(ComponentModel model) { 25: switch (model.Name) { 26: case "Products" : 27: return new [] { 28: "GetProducts", 29: "LoadProduct", 30: "Save", 31: "Update" 32: }; 33:   34: case "Categories" : 35: return new [] { 36: "GetProducts" 37: }; 38:   39: default : 40: throw new ArgumentException("Invalid type"); 41: } 42: } 43:   44: public DirectMethodType GetMethodType(ComponentModel model, MethodInfo method) { 45: if (method.Name.StartsWith("Save") || method.Name.StartsWith("Update")) 46: return DirectMethodType.FormSubmit; 47: 48: else if (method.Name.StartsWith("Load")) 49: return DirectMethodType.FormLoad; 50:   51: else 52: return DirectMethodType.Direct; 53: } 54:   55: #endregion 56: }   And there you have it, your own custom method resolver.  Pretty easy and pretty open ended!

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• Quick guide to Oracle IRM 11g: Classification design

  - by Simon Thorpe

  Quick guide to Oracle IRM 11g indexThis is the final article in the quick guide to Oracle IRM. If you've followed everything prior you will now have a fully functional and tested Information Rights Management service. It doesn't matter if you've been following the 10g or 11g guide as this next article is common to both. ContentsWhy this is the most important part... Understanding the classification and standard rights model Identifying business use cases Creating an effective IRM classification modelOne single classification across the entire businessA context for each and every possible granular use caseWhat makes a good context? Deciding on the use of roles in the context Reviewing the features and security for context roles Summary Why this is the most important part...Now the real work begins, installing and getting an IRM system running is as simple as following instructions. However to actually have an IRM technology easily protecting your most sensitive information without interfering with your users existing daily work flows and be able to scale IRM across the entire business, requires thought into how confidential documents are created, used and distributed. This article is going to give you the information you need to ask the business the right questions so that you can deploy your IRM service successfully. The IRM team here at Oracle have over 10 years of experience in helping customers and it is important you understand the following to be successful in securing access to your most confidential information. Whatever you are trying to secure, be it mergers and acquisitions information, engineering intellectual property, health care documentation or financial reports. No matter what type of user is going to access the information, be they employees, contractors or customers, there are common goals you are always trying to achieve.Securing the content at the earliest point possible and do it automatically. Removing the dependency on the user to decide to secure the content reduces the risk of mistakes significantly and therefore results a more secure deployment. K.I.S.S. (Keep It Simple Stupid) Reduce complexity in the rights/classification model. Oracle IRM lets you make changes to access to documents even after they are secured which allows you to start with a simple model and then introduce complexity once you've understood how the technology is going to be used in the business. After an initial learning period you can review your implementation and start to make informed decisions based on user feedback and administration experience. Clearly communicate to the user, when appropriate, any changes to their existing work practice. You must make every effort to make the transition to sealed content as simple as possible. For external users you must help them understand why you are securing the documents and inform them the value of the technology to both your business and them. Before getting into the detail, I must pay homage to Martin White, Vice President of client services in SealedMedia, the company Oracle acquired and who created Oracle IRM. In the SealedMedia years Martin was involved with every single customer and was key to the design of certain aspects of the IRM technology, specifically the context model we will be discussing here. Listening carefully to customers and understanding the flexibility of the IRM technology, Martin taught me all the skills of helping customers build scalable, effective and simple to use IRM deployments. No matter how well the engineering department designed the software, badly designed and poorly executed projects can result in difficult to use and manage, and ultimately insecure solutions. The advice and information that follows was born with Martin and he's still delivering IRM consulting with customers and can be found at www.thinkers.co.uk. It is from Martin and others that Oracle not only has the most advanced, scalable and usable document security solution on the market, but Oracle and their partners have the most experience in delivering successful document security solutions. Understanding the classification and standard rights model The goal of any successful IRM deployment is to balance the increase in security the technology brings without over complicating the way people use secured content and avoid a significant increase in administration and maintenance. With Oracle it is possible to automate the protection of content, deploy the desktop software transparently and use authentication methods such that users can open newly secured content initially unaware the document is any different to an insecure one. That is until of course they attempt to do something for which they don't have any rights, such as copy and paste to an insecure application or try and print. Central to achieving this objective is creating a classification model that is simple to understand and use but also provides the right level of complexity to meet the business needs. In Oracle IRM the term used for each classification is a "context". A context defines the relationship between.A group of related documents The people that use the documents The roles that these people perform The rights that these people need to perform their role The context is the key to the success of Oracle IRM. It provides the separation of the role and rights of a user from the content itself. Documents are sealed to contexts but none of the rights, user or group information is stored within the content itself. Sealing only places information about the location of the IRM server that sealed it, the context applied to the document and a few other pieces of metadata that pertain only to the document. This important separation of rights from content means that millions of documents can be secured against a single classification and a user needs only one right assigned to be able to access all documents. If you have followed all the previous articles in this guide, you will be ready to start defining contexts to which your sensitive information will be protected. But before you even start with IRM, you need to understand how your own business uses and creates sensitive documents and emails. Identifying business use cases Oracle is able to support multiple classification systems, but usually there is one single initial need for the technology which drives a deployment. This need might be to protect sensitive mergers and acquisitions information, engineering intellectual property, financial documents. For this and every subsequent use case you must understand how users create and work with documents, to who they are distributed and how the recipients should interact with them. A successful IRM deployment should start with one well identified use case (we go through some examples towards the end of this article) and then after letting this use case play out in the business, you learn how your users work with content, how well your communication to the business worked and if the classification system you deployed delivered the right balance. It is at this point you can start rolling the technology out further. Creating an effective IRM classification model Once you have selected the initial use case you will address with IRM, you need to design a classification model that defines the access to secured documents within the use case. In Oracle IRM there is an inbuilt classification system called the "context" model. In Oracle IRM 11g it is possible to extend the server to support any rights classification model, but the majority of users who are not using an application integration (such as Oracle IRM within Oracle Beehive) are likely to be starting out with the built in context model. Before looking at creating a classification system with IRM, it is worth reviewing some recognized standards and methods for creating and implementing security policy. A very useful set of documents are the ISO 17799 guidelines and the SANS security policy templates. First task is to create a context against which documents are to be secured. A context consists of a group of related documents (all top secret engineering research), a list of roles (contributors and readers) which define how users can access documents and a list of users (research engineers) who have been given a role allowing them to interact with sealed content. Before even creating the first context it is wise to decide on a philosophy which will dictate the level of granularity, the question is, where do you start? At a department level? By project? By technology? First consider the two ends of the spectrum... One single classification across the entire business Imagine that instead of having separate contexts, one for engineering intellectual property, one for your financial data, one for human resources personally identifiable information, you create one context for all documents across the entire business. Whilst you may have immediate objections, there are some significant benefits in thinking about considering this. Document security classification decisions are simple. You only have one context to chose from! User provisioning is simple, just make sure everyone has a role in the only context in the business. Administration is very low, if you assign rights to groups from the business user repository you probably never have to touch IRM administration again. There are however some obvious downsides to this model.All users in have access to all IRM secured content. So potentially a sales person could access sensitive mergers and acquisition documents, if they can get their hands on a copy that is. You cannot delegate control of different documents to different parts of the business, this may not satisfy your regulatory requirements for the separation and delegation of duties. Changing a users role affects every single document ever secured. Even though it is very unlikely a business would ever use one single context to secure all their sensitive information, thinking about this scenario raises one very important point. Just having one single context and securing all confidential documents to it, whilst incurring some of the problems detailed above, has one huge value. Once secured, IRM protected content can ONLY be accessed by authorized users. Just think of all the sensitive documents in your business today, imagine if you could ensure that only everyone you trust could open them. Even if an employee lost a laptop or someone accidentally sent an email to the wrong recipient, only the right people could open that file. A context for each and every possible granular use case Now let's think about the total opposite of a single context design. What if you created a context for each and every single defined business need and created multiple contexts within this for each level of granularity? Let's take a use case where we need to protect engineering intellectual property. Imagine we have 6 different engineering groups, and in each we have a research department, a design department and manufacturing. The company information security policy defines 3 levels of information sensitivity... restricted, confidential and top secret. Then let's say that each group and department needs to define access to information from both internal and external users. Finally add into the mix that they want to review the rights model for each context every financial quarter. This would result in a huge amount of contexts. For example, lets just look at the resulting contexts for one engineering group. Q1FY2010 Restricted Internal - Engineering Group 1 - Research Q1FY2010 Restricted Internal - Engineering Group 1 - Design Q1FY2010 Restricted Internal - Engineering Group 1 - Manufacturing Q1FY2010 Restricted External- Engineering Group 1 - Research Q1FY2010 Restricted External - Engineering Group 1 - Design Q1FY2010 Restricted External - Engineering Group 1 - Manufacturing Q1FY2010 Confidential Internal - Engineering Group 1 - Research Q1FY2010 Confidential Internal - Engineering Group 1 - Design Q1FY2010 Confidential Internal - Engineering Group 1 - Manufacturing Q1FY2010 Confidential External - Engineering Group 1 - Research Q1FY2010 Confidential External - Engineering Group 1 - Design Q1FY2010 Confidential External - Engineering Group 1 - Manufacturing Q1FY2010 Top Secret Internal - Engineering Group 1 - Research Q1FY2010 Top Secret Internal - Engineering Group 1 - Design Q1FY2010 Top Secret Internal - Engineering Group 1 - Manufacturing Q1FY2010 Top Secret External - Engineering Group 1 - Research Q1FY2010 Top Secret External - Engineering Group 1 - Design Q1FY2010 Top Secret External - Engineering Group 1 - Manufacturing Now multiply the above by 6 for each engineering group, 18 contexts. You are then creating/reviewing another 18 every 3 months. After a year you've got 72 contexts. What would be the advantages of such a complex classification model? You can satisfy very granular rights requirements, for example only an authorized engineering group 1 researcher can create a top secret report for access internally, and his role will be reviewed on a very frequent basis. Your business may have very complex rights requirements and mapping this directly to IRM may be an obvious exercise. The disadvantages of such a classification model are significant...Huge administrative overhead. Someone in the business must manage, review and administrate each of these contexts. If the engineering group had a single administrator, they would have 72 classifications to reside over each year. From an end users perspective life will be very confusing. Imagine if a user has rights in just 6 of these contexts. They may be able to print content from one but not another, be able to edit content in 2 contexts but not the other 4. Such confusion at the end user level causes frustration and resistance to the use of the technology. Increased synchronization complexity. Imagine a user who after 3 years in the company ends up with over 300 rights in many different contexts across the business. This would result in long synchronization times as the client software updates all your offline rights. Hard to understand who can do what with what. Imagine being the VP of engineering and as part of an internal security audit you are asked the question, "What rights to researchers have to our top secret information?". In this complex model the answer is not simple, it would depend on many roles in many contexts. Of course this example is extreme, but it highlights that trying to build many barriers in your business can result in a nightmare of administration and confusion amongst users. In the real world what we need is a balance of the two. We need to seek an optimum number of contexts. Too many contexts are unmanageable and too few contexts does not give fine enough granularity. What makes a good context? Good context design derives mainly from how well you understand your business requirements to secure access to confidential information. Some customers I have worked with can tell me exactly the documents they wish to secure and know exactly who should be opening them. However there are some customers who know only of the government regulation that requires them to control access to certain types of information, they don't actually know where the documents are, how they are created or understand exactly who should have access. Therefore you need to know how to ask the business the right questions that lead to information which help you define a context. First ask these questions about a set of documentsWhat is the topic? Who are legitimate contributors on this topic? Who are the authorized readership? If the answer to any one of these is significantly different, then it probably merits a separate context. Remember that sealed documents are inherently secure and as such they cannot leak to your competitors, therefore it is better sealed to a broad context than not sealed at all. Simplicity is key here. Always revert to the first extreme example of a single classification, then work towards essential complexity. If there is any doubt, always prefer fewer contexts. Remember, Oracle IRM allows you to change your mind later on. You can implement a design now and continue to change and refine as you learn how the technology is used. It is easy to go from a simple model to a more complex one, it is much harder to take a complex model that is already embedded in the work practice of users and try to simplify it. It is also wise to take a single use case and address this first with the business. Don't try and tackle many different problems from the outset. Do one, learn from the process, refine it and then take what you have learned into the next use case, refine and continue. Once you have a good grasp of the technology and understand how your business will use it, you can then start rolling out the technology wider across the business. Deciding on the use of roles in the context Once you have decided on that first initial use case and a context to create let's look at the details you need to decide upon. For each context, identify; Administrative rolesBusiness owner, the person who makes decisions about who may or may not see content in this context. This is often the person who wanted to use IRM and drove the business purchase. They are the usually the person with the most at risk when sensitive information is lost. Point of contact, the person who will handle requests for access to content. Sometimes the same as the business owner, sometimes a trusted secretary or administrator. Context administrator, the person who will enact the decisions of the Business Owner. Sometimes the point of contact, sometimes a trusted IT person. Document related rolesContributors, the people who create and edit documents in this context. Reviewers, the people who are involved in reviewing documents but are not trusted to secure information to this classification. This role is not always necessary. (See later discussion on Published-work and Work-in-Progress) Readers, the people who read documents from this context. Some people may have several of the roles above, which is fine. What you are trying to do is understand and define how the business interacts with your sensitive information. These roles obviously map directly to roles available in Oracle IRM. Reviewing the features and security for context roles At this point we have decided on a classification of information, understand what roles people in the business will play when administrating this classification and how they will interact with content. The final piece of the puzzle in getting the information for our first context is to look at the permissions people will have to sealed documents. First think why are you protecting the documents in the first place? It is to prevent the loss of leaking of information to the wrong people. To control the information, making sure that people only access the latest versions of documents. You are not using Oracle IRM to prevent unauthorized people from doing legitimate work. This is an important point, with IRM you can erect many barriers to prevent access to content yet too many restrictions and authorized users will often find ways to circumvent using the technology and end up distributing unprotected originals. Because IRM is a security technology, it is easy to get carried away restricting different groups. However I would highly recommend starting with a simple solution with few restrictions. Ensure that everyone who reasonably needs to read documents can do so from the outset. Remember that with Oracle IRM you can change rights to content whenever you wish and tighten security. Always return to the fact that the greatest value IRM brings is that ONLY authorized users can access secured content, remember that simple "one context for the entire business" model. At the start of the deployment you really need to aim for user acceptance and therefore a simple model is more likely to succeed. As time passes and users understand how IRM works you can start to introduce more restrictions and complexity. Another key aspect to focus on is handling exceptions. If you decide on a context model where engineering can only access engineering information, and sales can only access sales data. Act quickly when a sales manager needs legitimate access to a set of engineering documents. Having a quick and effective process for permitting other people with legitimate needs to obtain appropriate access will be rewarded with acceptance from the user community. These use cases can often be satisfied by integrating IRM with a good Identity & Access Management technology which simplifies the process of assigning users the correct business roles. The big print issue... Printing is often an issue of contention, users love to print but the business wants to ensure sensitive information remains in the controlled digital world. There are many cases of physical document loss causing a business pain, it is often overlooked that IRM can help with this issue by limiting the ability to generate physical copies of digital content. However it can be hard to maintain a balance between security and usability when it comes to printing. Consider the following points when deciding about whether to give print rights. Oracle IRM sealed documents can contain watermarks that expose information about the user, time and location of access and the classification of the document. This information would reside in the printed copy making it easier to trace who printed it. Printed documents are slower to distribute in comparison to their digital counterparts, so time sensitive information in printed format may present a lower risk. Print activity is audited, therefore you can monitor and react to users abusing print rights. Summary In summary it is important to think carefully about the way you create your context model. As you ask the business these questions you may get a variety of different requirements. There may be special projects that require a context just for sensitive information created during the lifetime of the project. There may be a department that requires all information in the group is secured and you might have a few senior executives who wish to use IRM to exchange a small number of highly sensitive documents with a very small number of people. Oracle IRM, with its very flexible context classification system, can support all of these use cases. The trick is to introducing the complexity to deliver them at the right level. In another article i'm working on I will go through some examples of how Oracle IRM might map to existing business use cases. But for now, this article covers all the important questions you need to get your IRM service deployed and successfully protecting your most sensitive information.

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• Sharing data between graphics and physics engine in the game?

  - by PolGraphic

  I'm writing the game engine that consists of few modules. Two of them are the graphics engine and the physics engine. I wonder if it's a good solution to share data between them? Two ways (sharing or not) looks like that: Without sharing data GraphicsModel{ //some common for graphics and physics data like position //some only graphic data //like textures and detailed model's verticles that physics doesn't need }; PhysicsModel{ //some common for graphics and physics data like position //some only physics data //usually my physics data contains A LOT more informations than graphics data } engine3D->createModel3D(...); physicsEngine->createModel3D(...); //connect graphics and physics data //e.g. update graphics model's position when physics model's position will change I see two main problems: A lot of redundant data (like two positions for both physics and graphics data) Problem with updating data (I have to manually update graphics data when physics data changes) With sharing data Model{ //some common for graphics and physics data like position }; GraphicModel : public Model{ //some only graphics data //like textures and detailed model's verticles that physics doesn't need }; PhysicsModel : public Model{ //some only physics data //usually my physics data contains A LOT more informations than graphics data } model = engine3D->createModel3D(...); physicsEngine->assingModel3D(&model); //will cast to //PhysicsModel for it's purposes?? //when physics changes anything (like position) in model //(which it treats like PhysicsModel), the position for graphics data //will change as well (because it's the same model) Problems here: physicsEngine cannot create new objects, just "assing" existing ones from engine3D (somehow it looks more anti-independent for me) Casting data in assingModel3D function physicsEngine and graphicsEngine must be careful - they cannot delete data when they don't need them (because second one may need it). But it's rare situation. Moreover, they can just delete the pointer, not the object. Or we can assume that graphicsEngine will delete objects, physicsEngine just pointers to them. Which way is better? Which will produce more problems in the future? I like the second solution more, but I wonder why most graphics and physics engines prefer the first one (maybe because they normally make only graphics or only physics engine and somebody else connect them in the game?). Have they any more hidden pros & contras?

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• How do I Integrate Production Database Hot Fixes into Shared Database Development model?

  - by TetonSig

  We are using SQL Source Control 3, SQL Compare, SQL Data Compare from RedGate, Mercurial repositories, TeamCity and a set of 4 environments including production. I am working on getting us to a dedicated environment per developer, but for at least the next 6 months we are stuck with a shared model. To summarize our current system, we have a DEV SQL server where developers first make changes/additions. They commit their changes through SQL Source Control to a local hgdev repository. When they execute an hg push to the main repository, TeamCity listens for that and then (among other things) pushes hgdev repository to hgrc. Another TeamCity process listens for that and does a pull from hgrc and deploys the latest to a QA SQL Server where regression and integration tests are run. When those are passed a push from hgrc to hgprod occurs. We do a compare of hgprod to our PREPROD SQL Server and generate deployment/rollback scripts for our production release. Separate from the above we have database Hot Fixes that will need to be applied in between releases. The process there is for our Operations team make changes on the PreProd database, and then after testing, to use SQL Source Control to commit their hot fix changes to hgprod from the PREPROD database, and then do a compare from hgprod to PRODUCTION, create deployment scripts and run them on PRODUCTION. If we were in a dedicated database per developer model, we could simply automatically push hgprod back to hgdev and merge in the hot fix change (through TeamCity monitoring for hgprod checkins) and then developers would pick it up and merge it to their local repository and database periodically. However, given that with a shared model the DEV database itself is the source of all changes, this won't work. Pushing hotfixes back to hgdev will show up in SQL Source Control as being different than DEV SQL Server and therefore we need to overwrite the reposistory with the "change" from the DEV SQL Server. My only workaround so far is to just have OPS assign a developer the hotfix ticket with a script attached and then we run their hotfixes against DEV ourselves to merge them back in. I'm not happy with that solution. Other than working faster to get to dedicated environment, are they other ways to keep this loop going automatically?

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• Why do meshes show up as bones in the Model class?

  - by Itamar Marom

  Right now I'm working on a 3D game and I've come across something very weird. When I created the model in Blender, I added an armature named "MyBone" to the stage and attached a cube ("MyCube") to it, so that when I move the armature, the cube moves with it. I exported this as an FBX and loaded it as a Model object. What I expected to see was: But what I got was this: I'm really confused. Why is the mesh I created showing up in the bone list? And what's Root Node? Here are the .blend and .fbx files: here or here. Thanks.

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• Let a model instance choose appropriate view class using category. Is it good design?

  - by Denis Mikhaylov

  Assume I have abstract base model class called MoneySource. And two realizations BankCard and CellularAccount. In MoneysSourceListViewController I want to display a list of them, but with ListItemView different for each MoneySource subclass. What if I define a category on MoneySource @interface MoneySource (ListItemView) - (Class)listItemViewClass; @end And then override it for each concrete sublcass of MoneySource, returning suitable view class. @implementation CellularAccount (ListItemView) - (Class)listItemViewClass { return [BankCardListView class]; } @end @implementation BankCard (ListItemView) - (Class)listItemViewClass { return [CellularAccountListView class]; } @end so I can ask model object about its view, not violating MVC principles, and avoiding class introspection or if constructions. Thank you!

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• Use a custom value object or a Guid as an entity identifier in a distributed system?

  - by Kazark

  tl;dr I've been told that in domain-driven design, an identifier for an entity could be a custom value object, i.e. something other than Guid, string, int, etc. Can this really be advisable in a distributed system? Long version I will invent an situation analogous to the one I am currently facing. Say I have a distributed system in which a central concept is an egg. The system allows you to order eggs and see spending reports and inventory-centric data such as quantity on hand, usage, valuation and what have you. There area variety of services backing these behaviors. And say there is also another app which allows you to compose recipes that link to a particular egg type. Now egg type is broken down by the species—ostrich, goose, duck, chicken, quail. This is fine and dandy because it means that users don't end up with ostrich eggs when they wanted quail eggs and whatnot. However, we've been getting complaints because jumbo chicken eggs are not even close to equivalent to small ones. The price is different, and they really aren't substitutable in recipes. And here we thought we were doing users a favor by not overwhelming them with too many options. Currently each of the services (say, OrderSubmitter, EggTypeDefiner, SpendingReportsGenerator, InventoryTracker, RecipeCreator, RecipeTracker, or whatever) are identifying egg types with an industry-standard integer representation the species (let's call it speciesCode). We realize we've goofed up because this change could effect every service. There are two basic proposed solutions: Use a predefined identifier type like Guid as the eggTypeID throughout all the services, but make EggTypeDefiner the only service that knows that this maps to a speciesCode and eggSizeCode (and potentially to an isOrganic flag in the future, or whatever). Use an EggTypeID value object which is a combination of speciesCode and eggSizeCode in every service. I've proposed the first solution because I'm hoping it better encapsulates the definition of what an egg type is in the EggTypeDefiner and will be more resilient to changes, say if some people now want to differentiate eggs by whether or not they are "organic". The second solution is being suggested by some people who understand DDD better than I do in the hopes that less enrichment and lookup will be necessary that way, with the justification that in DDD using a value object as an ID is fine. Also, they are saying that EggTypeDefiner is not a domain and EggType is not an entity and as such should not have a Guid for an ID. However, I'm not sure the second solution is viable. This "value object" is going to have to be serialized into JSON and URLs for GET requests and used with a variety of technologies (C#, JavaScript...) which breaks encapsulation and thus removes any behavior of the identifier value object (is either of the fields optional? etc.) Is this a case where we want to avoid something that would normally be fine in DDD because we are trying to do DDD in a distributed fashion? Summary Can it be a good idea to use a custom value object as an identifier in a distributed system (solution #2)?

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• Core Data Migration - "Can't add source store" error

  - by Tofrizer

  Hi, In my iPhone app I'm using Core Data and I've made changes to my data model that cannot be automatically migrated over (i.e. added new relationships). I added the data model version (Design - Data Model - Add Model Version) and applied my new data model changes to the new version 2. I then created a mapping object model and set the Source and Destination models to their correct data models (old and new respectively). When I run the app and call the persistentStoreCoordinator, my app barfs with the following: 2010-02-27 02:40:30.922 XXXX[73578:20b] Unresolved error Error Domain=NSCocoaErrorDomain Code=134110 UserInfo=0xfc2240 "Operation could not be completed. (Cocoa error 134110.)", { NSUnderlyingError = Error Domain=NSCocoaErrorDomain Code=134130 UserInfo=0xfbb3a0 "Operation could not be completed. (Cocoa error 134130.)"; reason = "Can't add source store"; } FWIW (not much i think) I've also made the usual code changes in persistentStoreCoordinator to use the NSMigratePersistentStoresAutomaticallyOption and NSInferMappingModelAutomaticallyOption (for future data model changes that can be automatically migrated). More relevantly, my managedObjectModel is created by calling initWithContentsOfURL where the file/resource type is "momd". I've tried updating both the source and destination model in the mapping model (Design - Mapping Model - Update XXX Model) as well as deleted the mapping model and recreated it. I've cleaned and re-built but all to no avail. I still get the above error message. Any pointers/thoughts on how I can further debug or resolve this problem please? I haven't posted any code snippets because this feels much more like a build environment issue (and my code is very standard - just the usual core data code to handle migrations using a mapping model but I'm happy to show the code if it helps). Appreciate any help. Thanks

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• Box2dx: Usage of World.QueryAABB?

  - by Rosarch

  I'm using Box2dx with C#/XNA. I'm trying to write a function that determines if a body could exist in a given point without colliding with anything: /// <summary> /// Can gameObject exist with start Point without colliding with anything? /// </summary> internal bool IsAvailableArea(GameObjectModel model, Vector2 point) { Vector2 originalPosition = model.Body.Position; model.Body.Position = point; // less risky would be to use a deep clone AABB collisionBox; model.Body.GetFixtureList().GetAABB(out collisionBox); // how is this supposed to work? physicsWorld.QueryAABB(x => true, ref collisionBox); model.Body.Position = originalPosition; return true; } Is there a better way to go about doing this? How is World.QueryAABB supposed to work? Here is an earlier attempt. It is broken; it always returns false. /// <summary> /// Can gameObject exist with start Point without colliding with anything? /// </summary> internal bool IsAvailableArea(GameObjectModel model, Vector2 point) { Vector2 originalPosition = model.Body.Position; model.Body.Position = point; // less risky would be to use a deep clone AABB collisionBox; model.Body.GetFixtureList().GetAABB(out collisionBox); ICollection<GameObjectController> gameObjects = worldQueryEngine.GameObjectsForPredicate(x => ! x.Model.Passable); foreach (GameObjectController controller in gameObjects) { AABB potentialCollidingBox; controller.Model.Body.GetFixtureList().GetAABB(out potentialCollidingBox); if (AABB.TestOverlap(ref collisionBox, ref potentialCollidingBox)) { model.Body.Position = originalPosition; return false; // there is something that will collide at this point } } model.Body.Position = originalPosition; return true; }

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• Movement prediction for non-shooters

  - by ShadowChaser

  I'm working on an isometric 2D game with moderate-scale multiplayer, approximately 20-30 players connected at once to a persistent server. I've had some difficulty getting a good movement prediction implementation in place. Physics/Movement The game doesn't have a true physics implementation, but uses the basic principles to implement movement. Rather than continually polling input, state changes (ie/ mouse down/up/move events) are used to change the state of the character entity the player is controlling. The player's direction (ie/ north-east) is combined with a constant speed and turned into a true 3D vector - the entity's velocity. In the main game loop, "Update" is called before "Draw". The update logic triggers a "physics update task" that tracks all entities with a non-zero velocity uses very basic integration to change the entities position. For example: entity.Position += entity.Velocity.Scale(ElapsedTime.Seconds) (where "Seconds" is a floating point value, but the same approach would work for millisecond integer values). The key point is that no interpolation is used for movement - the rudimentary physics engine has no concept of a "previous state" or "current state", only a position and velocity. State Change and Update Packets When the velocity of the character entity the player is controlling changes, a "move avatar" packet is sent to the server containing the entity's action type (stand, walk, run), direction (north-east), and current position. This is different from how 3D first person games work. In a 3D game the velocity (direction) can change frame to frame as the player moves around. Sending every state change would effectively transmit a packet per frame, which would be too expensive. Instead, 3D games seem to ignore state changes and send "state update" packets on a fixed interval - say, every 80-150ms. Since speed and direction updates occur much less frequently in my game, I can get away with sending every state change. Although all of the physics simulations occur at the same speed and are deterministic, latency is still an issue. For that reason, I send out routine position update packets (similar to a 3D game) but much less frequently - right now every 250ms, but I suspect with good prediction I can easily boost it towards 500ms. The biggest problem is that I've now deviated from the norm - all other documentation, guides, and samples online send routine updates and interpolate between the two states. It seems incompatible with my architecture, and I need to come up with a better movement prediction algorithm that is closer to a (very basic) "networked physics" architecture. The server then receives the packet and determines the players speed from it's movement type based on a script (Is the player able to run? Get the player's running speed). Once it has the speed, it combines it with the direction to get a vector - the entity's velocity. Some cheat detection and basic validation occurs, and the entity on the server side is updated with the current velocity, direction, and position. Basic throttling is also performed to prevent players from flooding the server with movement requests. After updating its own entity, the server broadcasts an "avatar position update" packet to all other players within range. The position update packet is used to update the client side physics simulations (world state) of the remote clients and perform prediction and lag compensation. Prediction and Lag Compensation As mentioned above, clients are authoritative for their own position. Except in cases of cheating or anomalies, the client's avatar will never be repositioned by the server. No extrapolation ("move now and correct later") is required for the client's avatar - what the player sees is correct. However, some sort of extrapolation or interpolation is required for all remote entities that are moving. Some sort of prediction and/or lag-compensation is clearly required within the client's local simulation / physics engine. Problems I've been struggling with various algorithms, and have a number of questions and problems: Should I be extrapolating, interpolating, or both? My "gut feeling" is that I should be using pure extrapolation based on velocity. State change is received by the client, client computes a "predicted" velocity that compensates for lag, and the regular physics system does the rest. However, it feels at odds to all other sample code and articles - they all seem to store a number of states and perform interpolation without a physics engine. When a packet arrives, I've tried interpolating the packet's position with the packet's velocity over a fixed time period (say, 200ms). I then take the difference between the interpolated position and the current "error" position to compute a new vector and place that on the entity instead of the velocity that was sent. However, the assumption is that another packet will arrive in that time interval, and it's incredibly difficult to "guess" when the next packet will arrive - especially since they don't all arrive on fixed intervals (ie/ state changes as well). Is the concept fundamentally flawed, or is it correct but needs some fixes / adjustments? What happens when a remote player stops? I can immediately stop the entity, but it will be positioned in the "wrong" spot until it moves again. If I estimate a vector or try to interpolate, I have an issue because I don't store the previous state - the physics engine has no way to say "you need to stop after you reach position X". It simply understands a velocity, nothing more complex. I'm reluctant to add the "packet movement state" information to the entities or physics engine, since it violates basic design principles and bleeds network code across the rest of the game engine. What should happen when entities collide? There are three scenarios - the controlling player collides locally, two entities collide on the server during a position update, or a remote entity update collides on the local client. In all cases I'm uncertain how to handle the collision - aside from cheating, both states are "correct" but at different time periods. In the case of a remote entity it doesn't make sense to draw it walking through a wall, so I perform collision detection on the local client and cause it to "stop". Based on point #2 above, I might compute a "corrected vector" that continually tries to move the entity "through the wall" which will never succeed - the remote avatar is stuck there until the error gets too high and it "snaps" into position. How do games work around this?

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• Data-driven animation states

  - by user8363

  I'm trying to handle animations in a 2D game engine hobby project, without hard-coding them. Hard coding animation states seems like a common but very strange phenomenon, to me. A little background: I'm working with an entity system where components are bags of data and subsystems act upon them. I chose to use a polling system to update animation states. With animation states I mean: "walking_left", "running_left", "walking_right", "shooting", ... My idea to handle animations was to design it as a data driven model. Data could be stored in an xml file, a rdbms, ... And could be loaded at the start of a game / level/ ... This way you can easily edit animations and transitions without having to go change the code everywhere in your game. As an example I made an xml draft of the data definitions I had in mind. One very important piece of data would simply be the description of an animation. An animation would have a unique id (a descriptive name). It would hold a reference id to an image (the sprite sheet it uses, because different animations may use different sprite sheets). The frames per second to run the animation on. The "replay" here defines if an animation should be run once or infinitely. Then I defined a list of rectangles as frames. <animation id='WIZARD_WALK_LEFT'> <image id='WIZARD_WALKING' /> <fps>50</fps> <replay>true</replay> <frames> <rectangle> <x>0</x> <y>0</y> <width>45</width> <height>45</height> </rectangle> <rectangle> <x>45</x> <y>0</y> <width>45</width> <height>45</height> </rectangle> </frames> </animation> Animation data would be loaded and held in an animation resource pool and referenced by game entities that are using it. It would be treated as a resource like an image, a sound, a texture, ... The second piece of data to define would be a state machine to handle animation states and transitions. This defines each state a game entity can be in, which states it can transition to and what triggers that state change. This state machine would differ from entity to entity. Because a bird might have states "walking" and "flying" while a human would only have the state "walking". However it could be shared by different entities because multiple humans will probably have the same states (especially when you define some common NPCs like monsters, etc). Additionally an orc might have the same states as a human. Just to demonstrate that this state definition might be shared but only by a select group of game entities. <state id='IDLE'> <event trigger='LEFT_DOWN' goto='MOVING_LEFT' /> <event trigger='RIGHT_DOWN' goto='MOVING_RIGHT' /> </state> <state id='MOVING_LEFT'> <event trigger='LEFT_UP' goto='IDLE' /> <event trigger='RIGHT_DOWN' goto='MOVING_RIGHT' /> </state> <state id='MOVING_RIGHT'> <event trigger='RIGHT_UP' goto='IDLE' /> <event trigger='LEFT_DOWN' goto='MOVING_LEFT' /> </state> These states can be handled by a polling system. Each game tick it grabs the current state of a game entity and checks all triggers. If a condition is met it changes the entity's state to the "goto" state. The last part I was struggling with was how to bind animation data and animation states to an entity. The most logical approach seemed to me to add a pointer to the state machine data an entity uses and to define for each state in that machine what animation it uses. Here is an xml example how I would define the animation behavior and graphical representation of some common entities in a game, by addressing animation state and animation data id. Note that both "wizard" and "orc" have the same animation states but a different animation. Also, a different animation could mean a different sprite sheet, or even a different sequence of animations (an animation could be longer or shorter). <entity name="wizard"> <state id="IDLE" animation="WIZARD_IDLE" /> <state id="MOVING_LEFT" animation="WIZARD_WALK_LEFT" /> </entity> <entity name="orc"> <state id="IDLE" animation="ORC_IDLE" /> <state id="MOVING_LEFT" animation="ORC_WALK_LEFT" /> </entity> When the entity is being created it would add a list of states with state machine data and an animation data reference. In the future I would use the entity system to build whole entities by defining components in a similar xml format. -- This is what I have come up with after some research. However I had some trouble getting my head around it, so I was hoping op some feedback. Is there something here what doesn't make sense, or is there a better way to handle these things? I grasped the idea of iterating through frames but I'm having trouble to take it a step further and this is my attempt to do that.

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• Big smart ViewModels, dumb Views, and any model, the best MVVM approach?

  - by Edward Tanguay

  The following code is a refactoring of my previous MVVM approach (Fat Models, skinny ViewModels and dumb Views, the best MVVM approach?) in which I moved the logic and INotifyPropertyChanged implementation from the model back up into the ViewModel. This makes more sense, since as was pointed out, you often you have to use models that you either can't change or don't want to change and so your MVVM approach should be able to work with any model class as it happens to exist. This example still allows you to view the live data from your model in design mode in Visual Studio and Expression Blend which I think is significant since you could have a mock data store that the designer connects to which has e.g. the smallest and largest strings that the UI can possibly encounter so that he can adjust the design based on those extremes. Questions: I'm a bit surprised that I even have to "put a timer" in my ViewModel since it seems like that is a function of INotifyPropertyChanged, it seems redundant, but it was the only way I could get the XAML UI to constantly (once per second) reflect the state of my model. So it would be interesting to hear anyone who may have taken this approach if you encountered any disadvantages down the road, e.g. with threading or performance. The following code will work if you just copy the XAML and code behind into a new WPF project. XAML: <Window x:Class="TestMvvm73892.Window1" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:local="clr-namespace:TestMvvm73892" Title="Window1" Height="300" Width="300"> <Window.Resources> <ObjectDataProvider x:Key="DataSourceCustomer" ObjectType="{x:Type local:CustomerViewModel}" MethodName="GetCustomerViewModel"/> </Window.Resources> <DockPanel DataContext="{StaticResource DataSourceCustomer}"> <StackPanel DockPanel.Dock="Top" Orientation="Horizontal"> <TextBlock Text="{Binding Path=FirstName}"/> <TextBlock Text=" "/> <TextBlock Text="{Binding Path=LastName}"/> </StackPanel> <StackPanel DockPanel.Dock="Top" Orientation="Horizontal"> <TextBlock Text="{Binding Path=TimeOfMostRecentActivity}"/> </StackPanel> </DockPanel> </Window> Code Behind: using System; using System.Windows; using System.ComponentModel; using System.Threading; namespace TestMvvm73892 { public partial class Window1 : Window { public Window1() { InitializeComponent(); } } //view model public class CustomerViewModel : INotifyPropertyChanged { private string _firstName; private string _lastName; private DateTime _timeOfMostRecentActivity; private Timer _timer; public string FirstName { get { return _firstName; } set { _firstName = value; this.RaisePropertyChanged("FirstName"); } } public string LastName { get { return _lastName; } set { _lastName = value; this.RaisePropertyChanged("LastName"); } } public DateTime TimeOfMostRecentActivity { get { return _timeOfMostRecentActivity; } set { _timeOfMostRecentActivity = value; this.RaisePropertyChanged("TimeOfMostRecentActivity"); } } public CustomerViewModel() { _timer = new Timer(CheckForChangesInModel, null, 0, 1000); } private void CheckForChangesInModel(object state) { Customer currentCustomer = CustomerViewModel.GetCurrentCustomer(); MapFieldsFromModeltoViewModel(currentCustomer, this); } public static CustomerViewModel GetCustomerViewModel() { CustomerViewModel customerViewModel = new CustomerViewModel(); Customer currentCustomer = CustomerViewModel.GetCurrentCustomer(); MapFieldsFromModeltoViewModel(currentCustomer, customerViewModel); return customerViewModel; } public static void MapFieldsFromModeltoViewModel(Customer model, CustomerViewModel viewModel) { viewModel.FirstName = model.FirstName; viewModel.LastName = model.LastName; viewModel.TimeOfMostRecentActivity = model.TimeOfMostRecentActivity; } public static Customer GetCurrentCustomer() { return Customer.GetCurrentCustomer(); } //INotifyPropertyChanged implementation public event PropertyChangedEventHandler PropertyChanged; private void RaisePropertyChanged(string property) { if (PropertyChanged != null) { PropertyChanged(this, new PropertyChangedEventArgs(property)); } } } //model public class Customer { public string FirstName { get; set; } public string LastName { get; set; } public DateTime TimeOfMostRecentActivity { get; set; } public static Customer GetCurrentCustomer() { return new Customer { FirstName = "Jim", LastName = "Smith", TimeOfMostRecentActivity = DateTime.Now }; } } }

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• After extending the User model in django, how do you create a ModelForm?

  - by mlissner

  I extended the User model in django to include several other variables, such as location, and employer. Now I'm trying to create a form that has the following fields: First name (from User) Last name (from User) Location (from UserProfile, which extends User via a foreign key) Employer (also from UserProfile) I have created a modelform: from django.forms import ModelForm from django.contrib import auth from alert.userHandling.models import UserProfile class ProfileForm(ModelForm): class Meta: # model = auth.models.User # this gives me the User fields model = UserProfile # this gives me the UserProfile fields So, my question is, how can I create a ModelForm that has access to all of the fields, whether they are from the User model or the UserProfile model? Hope this makes sense. I'll be happy to clarify if there are any questions.

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• Should I design the application or model (database) first?

  - by YonahW

  I am getting ready to start building a new web project in my spare time to bring to fruition an idea that has been bouncing around my head for a while. I have never gotten down whether I am better off first building the model and then the consuming application or the other way around. What are the best practices? What would you build first and why? I imagine that in general the application should generally drive the model, however the application like many websites really doesn't do much without the model. For some reason I find it easier at times to think in terms of the model since the application is really just actions on the model. Is this a poor way of thinking about things? What advantages/disadvantages does each option have?

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• How can I not render a button in my view if a given property off my model has no value?

  - by Lee Warner

  I'm new to web development. In my view, I want to conditionally show a button if Model.TemplateLocation (which is a string) is not null or empty. Below is the code that is rendering the button currently: <div class="WPButton MyButton"> <%=Html.ActionLink(Model.TemplateLinkName, "DownloadTemplate", "ExternalData", new ArgsDownloadTemplate { Path = Model.TemplateLocation, FileName = Model.TemplateFileNameForDownload }, new{})%> </div> Can I wrap some C# code in the <% %'s to test for Model.TemplateLocations value before I render that? I was told to look into @style = "display:none" somehow. Could that be what I need?

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• What is good practice in .NET system architecture design concerning multiple models and aggregates

  - by BuzzBubba

  I'm designing a larger enterprise architecture and I'm in a doubt about how to separate the models and design those. There are several points I'd like suggestions for: - models to define - way to define models Currently my idea is to define: Core (domain) model Repositories to get data to that domain model from a database or other store Business logic model that would contain business logic, validation logic and more specific versions of forms of data retrieval methods View models prepared for specifically formated data output that would be parsed by views of different kind (web, silverlight, etc). For the first model I'm puzzled at what to use and how to define the mode. Should this model entities contain collections and in what form? IList, IEnumerable or IQueryable collections? - I'm thinking of immutable collections which IEnumerable is, but I'd like to avoid huge data collections and to offer my Business logic layer access with LINQ expressions so that query trees get executed at Data level and retrieve only really required data for situations like the one when I'm retrieving a very specific subset of elements amongst thousands or hundreds of thousands. What if I have an item with several thousands of bids? I can't just make an IEnumerable collection of those on the model and then retrieve an item list in some Repository method or even Business model method. Should it be IQueryable so that I actually pass my queries to Repository all the way from the Business logic model layer? Should I just avoid collections in my domain model? Should I void only some collections? Should I separate Domain model and BusinessLogic model or integrate those? Data would be dealt trough repositories which would use Domain model classes. Should repositories be used directly using only classes from domain model like data containers? This is an example of what I had in mind: So, my Domain objects would look like (e.g.) public class Item { public string ItemName { get; set; } public int Price { get; set; } public bool Available { get; set; } private IList<Bid> _bids; public IQueryable<Bid> Bids { get { return _bids.AsQueryable(); } private set { _bids = value; } } public AddNewBid(Bid newBid) { _bids.Add(new Bid {.... } } Where Bid would be defined as a normal class. Repositories would be defined as data retrieval factories and used to get data into another (Business logic) model which would again be used to get data to ViewModels which would then be rendered by different consumers. I would define IQueryable interfaces for all aggregating collections to get flexibility and minimize data retrieved from real data store. Or should I make Domain Model "anemic" with pure data store entities and all collections define for business logic model? One of the most important questions is, where to have IQueryable typed collections? - All the way from Repositories to Business model or not at all and expose only solid IList and IEnumerable from Repositories and deal with more specific queries inside Business model, but have more finer grained methods for data retrieval within Repositories. So, what do you think? Have any suggestions?

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• GAE datastore querying integer fields

  - by ParanoidAndroid

  I notice strange behavior when querying the GAE datastore. Under certain circumstances Filter does not work for integer fields. The following java code reproduces the problem: log.info("start experiment"); DatastoreService datastore = DatastoreServiceFactory.getDatastoreService(); int val = 777; // create and store the first entity. Entity testEntity1 = new Entity(KeyFactory.createKey("Test", "entity1")); Object value = new Integer(val); testEntity1.setProperty("field", value); datastore.put(testEntity1); // create the second entity by using BeanUtils. Test test2 = new Test(); // just a regular bean with an int field test2.setField(val); Entity testEntity2 = new Entity(KeyFactory.createKey("Test", "entity2")); Map<String, Object> description = BeanUtilsBean.getInstance().describe(test2); for(Entry<String,Object> entry:description.entrySet()){ testEntity2.setProperty(entry.getKey(), entry.getValue()); } datastore.put(testEntity2); // now try to retrieve the entities from the database... Filter equalFilter = new FilterPredicate("field", FilterOperator.EQUAL, val); Query q = new Query("Test").setFilter(equalFilter); Iterator<Entity> iter = datastore.prepare(q).asIterator(); while (iter.hasNext()) { log.info("found entity: " + iter.next().getKey()); } log.info("experiment finished"); the log looks like this: INFO: start experiment INFO: found entity: Test("entity1") INFO: experiment finished For some reason it only finds the first entity even though both entities are actually stored in the datastore and both 'field' values are 777 (I see it in the Datastore Viewer)! Why does it matter how the entity is created? I would like to use BeanUtils, because it is convenient. The same problem occurs on the local devserver and when deployed to GAE.

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• ASP.NET MVC Framework

  - by Aamir Hasan

   MVC is a design pattern. A reusable "recipe" for constructing your application. Generally, you don't want your user interface code and data access code to be mixed together, it makes changing either one more difficult. By placing data access code into a "Model" object and user interface code into a "View" object, you can use a "Controller" object to act as a go-between, sending messages/calling methods on the view object when the data changes and vice versa. Model-view-controller (MVC) is an architectural pattern used in software engineering. In complex computer applications that present a large amount of data to the user, a developer often wishes to separate data (model) and user interface (view) concerns, so that changes to the user interface will not affect data handling, and that the data can be reorganized without changing the user interface. The model-view-controller solves this problem by decoupling data access and business logic from data presentation and user interaction, by introducing an intermediate component: the controller.Model:    The domain-specific representation of the information that the application operates. Domain logic adds meaning to raw data (e.g., calculating whether today is the user's birthday, or the totals, taxes, and shipping charges for shopping cart items).    Many applications use a persistent storage mechanism (such as a database) to store data. MVC does not specifically mention the data access layer because it is understood to be underneath or encapsulated by the Model.View:    Renders the model into a form suitable for interaction, typically a user interface element. Multiple views can exist for a single model for different purposes.Controller:    Processes and responds to events, typically user actions, and may invoke changes on the model.    

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• Finding the Right Solution to Source and Manage Your Contractors

  - by mark.rosenberg(at)oracle.com

  Many of our PeopleSoft Enterprise applications customers operate in service-based industries, and all of our customers have at least some internal service units, such as IT, marketing, and facilities. Employing the services of contractors, often referred to as "contingent labor," to deliver either or both internal and external services is common practice. As we've transitioned from an industrial age to a knowledge age, talent has become a primary competitive advantage for most organizations. Contingent labor offers talent on flexible terms; it offers the ability to scale up operations, close skill gaps, and manage risk in the process of delivering services. Talent comes from many sources and the rise in the contingent worker (contractor, consultant, temporary, part time) has increased significantly in the past decade and is expected to reach 40 percent in the next decade. Managing the total pool of talent in a seamless integrated fashion not only saves organizations money and increases efficiency, but creates a better place for workers of all kinds to work. Although the term "contingent labor" is frequently used to describe both contractors and employees who have flexible schedules and relationships with an organization, the remainder of this discussion focuses on contractors. The term "contingent labor" is used interchangeably with "contractor." Recognizing the importance of contingent labor, our PeopleSoft customers often ask our team, "What Oracle vendor management system (VMS) applications should I evaluate for managing contractors?" In response, I thought it would be useful to describe and compare the three most common Oracle-based options available to our customers. They are:   The enterprise licensed software model in which you implement and utilize the PeopleSoft Services Procurement (sPro) application and potentially other PeopleSoft applications;  The software-as-a-service model in which you gain access to a derivative of PeopleSoft sPro from an Oracle Business Process Outsourcing Partner; and  The managed service provider (MSP) model in which staffing industry professionals utilize either your enterprise licensed software or the software-as-a-service application to administer your contingent labor program. At this point, you may be asking yourself, "Why three options?" The answer is that since there is no "one size fits all" in terms of talent, there is also no "one size fits all" for effectively sourcing and managing contingent workers. Various factors influence how an organization thinks about and relates to its contractors, and each of the three Oracle-based options addresses an organization's needs and preferences differently. For the purposes of this discussion, I will describe the options with respect to (A) pricing and software provisioning models; (B) control and flexibility; (C) level of engagement with contractors; and (D) approach to sourcing, employment law, and financial settlement. Option 1:  Enterprise Licensed Software In this model, you purchase from Oracle the license and support for the applications you need. Typically, you license PeopleSoft sPro as your VMS tool for sourcing, monitoring, and paying your contract labor. In conjunction with sPro, you can also utilize PeopleSoft Human Capital Management (HCM) applications (if you do not already) to configure more advanced business processes for recruiting, training, and tracking your contractors. Many customers choose this enterprise license software model because of the functionality and natural integration of the PeopleSoft applications and because the cost for the PeopleSoft software is explicit. There is no fee per transaction to source each contractor under this model. Our customers that employ contractors to augment their permanent staff on billable client engagements often find this model appealing because there are no fees to affect their profit margins. With this model, you decide whether to have your own IT organization run the software or have the software hosted and managed by either Oracle or another application services provider. Your organization, perhaps with the assistance of consultants, configures, deploys, and operates the software for managing your contingent workforce. This model offers you the highest level of control and flexibility since your organization can configure the contractor process flow exactly to your business and security requirements and can extend the functionality with PeopleTools. This option has proven very valuable and applicable to our customers engaged in government contracting because their contingent labor management practices are subject to complex standards and regulations. Customers find a great deal of value in the application functionality and configurability the enterprise licensed software offers for managing contingent labor. Some examples of that functionality are... The ability to create a tiered network of preferred suppliers including competencies, pricing agreements, and elaborate candidate management capabilities. Configurable alerts and online collaboration for bid, resource requisition, timesheet, and deliverable entry, routing, and approval for both resource and deliverable-based services. The ability to manage contractors with the same PeopleSoft HCM and Projects applications that are used to manage the permanent workforce. Because it allows you to utilize much of the same PeopleSoft HCM and Projects application functionality for contractors that you use for permanent employees, the enterprise licensed software model supports the deepest level of engagement with the contingent workforce. For example, you can: fill job openings with contingent labor; guide contingent workers through essential safety and compliance training with PeopleSoft Enterprise Learning Management; and source contingent workers directly to project-based assignments in PeopleSoft Resource Management and PeopleSoft Program Management. This option enables contingent workers to collaborate closely with your permanent staff on complex, knowledge-based efforts - R&D projects, billable client contracts, architecture and engineering projects spanning multiple years, and so on. With the enterprise licensed software model, your organization maintains responsibility for the sourcing, onboarding (including adherence to employment laws), and financial settlement processes. This means your organization maintains on staff or hires the expertise in these domains to utilize the software and interact with suppliers and contractors. Option 2:  Software as a Service (SaaS) The effort involved in setting up and operating VMS software to handle a contingent workforce leads many organizations to seek a system that can be activated and configured within a few days and for which they can pay based on usage. Oracle's Business Process Outsourcing partner, Provade, Inc., provides exactly this option to our customers. Provade offers its vendor management software as a service over the Internet and usually charges your organization a fee that is a percentage of your total contingent labor spending processed through the Provade software. (Percentage of spend is the predominant fee model, although not the only one.) In addition to lower implementation costs, the effort of configuring and maintaining the software is largely upon Provade, not your organization. This can be very appealing to IT organizations that are thinly stretched supporting other important information technology initiatives. Built upon PeopleSoft sPro, the Provade solution is tailored for simple and quick deployment and administration. Provade has added capabilities to clone users rapidly and has simplified business documents, like work orders and change orders, to facilitate enterprise-wide, self-service adoption with little to no training. Provade also leverages Oracle Business Intelligence Enterprise Edition (OBIEE) to provide integrated spend analytics and dashboards. Although pure customization is more limited than with the enterprise licensed software model, Provade offers a very effective option for organizations that are regularly on-boarding and off-boarding high volumes of contingent staff hired to perform discrete support tasks (for example, order fulfillment during the holiday season, hourly clerical work, desktop technology repairs, and so on) or project tasks. The software is very configurable and at the same time very intuitive to even the most computer-phobic users. The level of contingent worker engagement your organization can achieve with the Provade option is generally the same as with the enterprise licensed software model since Provade can automatically establish contingent labor resources in your PeopleSoft applications. Provade has pre-built integrations to Oracle's PeopleSoft and the Oracle E-Business Suite procurement, projects, payables, and HCM applications, so that you can evaluate, train, assign, and track contingent workers like your permanent employees. Similar to the enterprise licensed software model, your organization is responsible for the contingent worker sourcing, administration, and financial settlement processes. This means your organization needs to maintain the staff expertise in these domains. Option 3:  Managed Services Provider (MSP) Whether you are using the enterprise licensed model or the SaaS model, you may want to engage the services of sourcing, employment, payroll, and financial settlement professionals to administer your contingent workforce program. Firms that offer this expertise are often referred to as "MSPs," and they are typically staffing companies that also offer permanent and temporary hiring services. (In fact, many of the major MSPs are Oracle applications customers themselves, and they utilize the PeopleSoft Solution for the Staffing Industry to run their own business operations.) Usually, MSPs place their staff on-site at your facilities, and they can utilize either your enterprise licensed PeopleSoft sPro application or the Provade VMS SaaS software to administer the network of suppliers providing contingent workers. When you utilize an MSP, there is a separate fee for the MSP's service that is typically funded by the participating suppliers of the contingent labor. Also in this model, the suppliers of the contingent labor (not the MSP) usually pay the contingent labor force. With an MSP, you are intentionally turning over business process control for the advantages associated with having someone else manage the processes. The software option you choose will to a certain extent affect your process flexibility; however, the MSPs are often able to adapt their processes to the unique demands of your business. When you engage an MSP, you will want to give some thought to the level of engagement and "partnering" you need with your contingent workforce. Because the MSP acts as an intermediary, it can be very valuable in handling high volume, routine contracting for which there is a relatively low need for "partnering" with the contingent workforce. However, if your organization (or part of your organization) engages contingent workers for high-profile client projects that require diplomacy, intensive amounts of interaction, and personal trust, introducing an MSP into the process may prove less effective than handling the process with your own staff. In fact, in many organizations, it is common to enlist an MSP to handle contractors working on internal projects and to have permanent employees handle the contractor relationships that affect the portion of the services portfolio focused on customer-facing, billable projects. One of the key advantages of enlisting an MSP is that you do not have to maintain the expertise required for orchestrating the sourcing, hiring, and paying of contingent workers.  These are the domain of the MSPs. If your own staff members are not prepared to manage the essential "overhead" processes associated with contingent labor, working with an MSP can make solid business sense. Proper administration of a contingent workforce can make the difference between project success and failure, operating profit and loss, and legal compliance and fines. Concluding Thoughts There is little doubt that thoughtfully and purposefully constructing a service delivery strategy that leverages the strengths of contingent workers can lead to better projects, deliverables, and business results. What requires a bit more thinking is determining the platform (or platforms) that will enable each part of your organization to best deliver on its mission.

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