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• Network communication for a turn based board game

  - by randooom

  Hi all, my first question here, so please don't be to harsh if something went wrong :) I'm currently a CS student (from Germany, if this info is of any use ;) ) and we got a, free selectable, programming assignment, which we have to write in a C++/CLI Windows Forms Application. My team, two others and me, decided to go for a network-compatible port of the board game Risk. We divided the work in 3 Parts, namely UI, game logic and network. Now we're on the part where we have to get everything working together and the big question mark is, how to get the clients synchronized with each other? Our approach so far is, that each client has all information necessary to calculate and/or execute all possible actions. Actually the clients have all information available at all, aside from the game-initializing phase (add players, select map, etc.), which needs one "super-client" with some extra stuff to control things. This is the standard scenario of our approach: player performs action, the action is valid and got executed on the players client action is sent over the network action is executed on the other clients The design (i.e. no or code so far) we came up with so far, is something like the following pseudo sequence diagram. Gui, Controller and Network implement all possible actions (i.e. all actions which change data) as methods from an interface. So each part can implement the method in a way to get their job done. Example with Action(): On the player side's Client: Player-->Gui.Action() Gui-->Controller.Action() Controller-->Logic.Action (Logic.Action() == NoError)? Controller-->Network.Action() Network-->Parser.ParseAction() Network.Send(msg) On all other clients: Network.Recv(msg) Network-->Parser.Deparse(msg) Parser-->Logic.Action() Logic-->Gui.Action() The questions: Is this a viable approach to our task? Any better/easier way to this? Recommendations, critique? Our knowledge (so you can better target your answer): We are on the beginner side, in regards to programming on a somewhat larger projects with a small team. All of us have some general programming experience and basic understanding of the .Net Libraries and Windows Forms. If you need any further information, please feel free to ask.

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• Have problems designing input and output for a calculator app

  - by zoul

  Hello! I am writing a button calculator. I have the code split into model, view and a controller. The model knows nothing about formatting, it is only concerned with numbers. All formatting is done in the view. The model gets its input as keypresses, each keypress is a part of an enum: typedef enum { kButtonUnknown = 0, kButtonMemoryClear = 100, kButtonMemoryPlus = 112, kButtonMemoryMinus = 109, kButtonMemoryRecall = 114, kButtonClear = 99, … }; When the user presses a button (say 1), the model receives a button code (kButtonNum1), adds the corresponding number to a string input buffer ("1") and updates the numeric output value (1.0). The controller then passes the numeric output value to the view that formats it (1). This is all plain, simple and clean, but does not really work. The problem is that when user enters a part of a number (say 0.00, going to enter 0.001), the input does not survive the way through model to view and the display says 0 instead of 0.00. I know why this happens ("0.00"::string parses to 0::double and that gets formatted as 0). What I don’t know is how to design the calculator so that the code stays clean and simple and the numbers will show up on screen exactly as the user types them. I’ve already come with some kind of solution, but that’s essentially a hack and breaks the beautiful and simple flow from the calculator model to the display. Ideas? Current solution keeps track of the calculator state. If the calculator is building a number, I take the calculator input buffer (a string) and directly set the display contents (also a string). Otherwise I take the proper path, ie. take the numeric calculator output, pass it to the view as a double and the view uses its internal formatter to create a string for the display. Example input: input | display | mode ------+---------+------------ 0 | 0 | from string 0. | 0. | from string 0.0 | 0.0 | from string 0.0+ | 0 | from number This is ugly. (1) The calculator has to expose its input buffer and state. (2) The view has to expose its display and allow setting its contents directly using a string. (3) I have to duplicate some of the formatting code to format the string I got from the calculator input buffer. If user enters 12345.000, I have to display 12,345.000 and therefore I’ve got to have a commification code for strings. Yuck.

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• Any simple approaches for managing customer data change requests for global reference files?

  - by Kelly Duke

  For the first time, I am developing in an environment in which there is a central repository for a number of different industry standard reference data tables and many different customers who need to select records from these industry standard reference data tables to fill in foreign key information for their customer specific records. Because these industry standard reference files are utilized by all customers, I want to reserve Create/Update/Delete access to these records for global product administrators. However, I would like to implement a (semi-)automated interface by which specific customers could request record additions, deletions or modifications to any of the industry standard reference files that are shared among all customers. I know I need something like a "data change request" table specifying: user id, user request datetime, request type (insert, modify, delete), a user entered text explanation of the change request, the user request's current status (pending, declined, completed), admin resolution datetime, admin id, an admin entered text description of the resolution, etc. What I can't figure out is how to elegantly handle the fact that these data change requests could apply to dozens of different tables with differing table column definitions. I would like to give the customer users making these data change requests a convenient way to enter their proposed record additions/modifications directly into CRUD screens that look very much like the reference table CRUD screens they don't have write/delete permissions for (with an additional text explanation and perhaps request priority field). I would also like to give the global admins a tool that allows them to view all the outstanding data change requests for the users they oversee sorted by date requested or user/date requested. Upon selecting a data change request record off the list, the admin would be directed to another CRUD screen that would be populated with the fields the customer users requested for the new/modified industry standard reference table record along with customer's text explanation, the request status and the text resolution explanation field. At this point the admin could accept/edit/reject the requested change and if accepted the affected industry standard reference file would be automatically updated with the appropriate fields and the data change request record's status, text resolution explanation and resolution datetime would all also be appropriately updated. However, I want to keep the actual production reference tables as simple as possible and free from these extraneous and typically null customer change request fields. I'd also like the data change request file to aggregate all data change requests across all the reference tables yet somehow "point to" the specific reference table and primary key in question for modification & deletion requests or the specific reference table and associated customer user entered field values in question for record creation requests. Does anybody have any ideas of how to design something like this effectively? Is there a cleaner, simpler way I am missing? Thank you so much for reading.

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• How can I model the data in a multi-language data editor in WPF with MVVM?

  - by Patrick Szalapski

  Are there any good practices to follow when designing a model/ViewModel to represent data in an app that will view/edit that data in multiple languages? Our top-level class--let's call it Course--contains several collection properties, say Books and TopicsCovered, which each might have a collection property among its data. For example, the data needs to represent course1.Books.First().Title in different languages, and course1.TopicsCovered.First().Name in different languages. We want a app that can edit any of the data for one given course in any of the available languages--as well as edit non-language-specific data, perhaps the Author of a Book (i.e. course1.Books.First().Author). We are having trouble figuring out how best to set up the model to enable binding in the XAML view. For example, do we replace (in the single-language model) each String with a collection of LanguageSpecificString instances? So to get the author in the current language: course1.Books.First().Author.Where(Function(a) a.Language = CurrentLanguage).SingleOrDefault If we do that, we cannot easily bind to any value in one given language, only to the collection of language values such as in an ItemsControl. <TextBox Text={Binding Author.???} /> <!-- no way to bind to the current language author --> Do we replace the top-level Course class with a collection of language-specific Courses? So to get the author in the current language: course1.GetLanguage(CurrentLanguage).Books.First.Author If we do that, we can only easily work with one language at a time; we might want a view to show one language and let the user edit the other. <TextBox Text={Binding Author} /> <!-- good --> <TextBlock Text={Binding ??? } /> <!-- no way to bind to the other language author --> Also, that has the disadvantage of not representing language-neutral data as such; every property (such as Author) would seem to be in multiple languages. Even non-string properties would be in multiple languages. Is there an option in between those two? Is there another way that we aren't thinking of? I realize this is somewhat vague, but it would seem to be a somewhat common problem to design for. Note: This is not a question about providing a multilingual UI, but rather about actually editing multi-language data in a flexible way.

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• Discovering a functional algorithm from a mutable one

  - by Garrett Rowe

  This isn't necessarily a Scala question, it's a design question that has to do with avoiding mutable state, functional thinking and that sort. It just happens that I'm using Scala. Given this set of requirements: Input comes from an essentially infinite stream of random numbers between 1 and 10 Final output is either SUCCEED or FAIL There can be multiple objects 'listening' to the stream at any particular time, and they can begin listening at different times so they all may have a different concept of the 'first' number; therefore listeners to the stream need to be decoupled from the stream itself. Pseudocode: if (first number == 1) SUCCEED else if (first number >= 9) FAIL else { first = first number rest = rest of stream for each (n in rest) { if (n == 1) FAIL else if (n == first) SUCCEED else continue } } Here is a possible mutable implementation: sealed trait Result case object Fail extends Result case object Succeed extends Result case object NoResult extends Result class StreamListener { private var target: Option[Int] = None def evaluate(n: Int): Result = target match { case None => if (n == 1) Succeed else if (n >= 9) Fail else { target = Some(n) NoResult } case Some(t) => if (n == t) Succeed else if (n == 1) Fail else NoResult } } This will work but smells to me. StreamListener.evaluate is not referentially transparent. And the use of the NoResult token just doesn't feel right. It does have the advantage though of being clear and easy to use/code. Besides there has to be a functional solution to this right? I've come up with 2 other possible options: Having evaluate return a (possibly new) StreamListener, but this means I would have to make Result a subtype of StreamListener which doesn't feel right. Letting evaluate take a Stream[Int] as a parameter and letting the StreamListener be in charge of consuming as much of the Stream as it needs to determine failure or success. The problem I see with this approach is that the class that registers the listeners should query each listener after each number is generated and take appropriate action immediately upon failure or success. With this approach, I don't see how that could happen since each listener is forcing evaluation of the Stream until it completes evaluation. There is no concept here of a single number generation. Is there any standard scala/fp idiom I'm overlooking here?

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• How can i convert this to a factory/abstract factory?

  - by Amitd

  I'm using MigraDoc to create a pdf document. I have business entities similar to the those used in MigraDoc. public class Page{ public List<PageContent> Content { get; set; } } public abstract class PageContent { public int Width { get; set; } public int Height { get; set; } public Margin Margin { get; set; } } public class Paragraph : PageContent{ public string Text { get; set; } } public class Table : PageContent{ public int Rows { get; set; } public int Columns { get; set; } //.... more } In my business logic, there are rendering classes for each type public interface IPdfRenderer<T> { T Render(MigraDoc.DocumentObjectModel.Section s); } class ParagraphRenderer : IPdfRenderer<MigraDoc.DocumentObjectModel.Paragraph> { BusinessEntities.PDF.Paragraph paragraph; public ParagraphRenderer(BusinessEntities.PDF.Paragraph p) { paragraph = p; } public MigraDoc.DocumentObjectModel.Paragraph Render(MigraDoc.DocumentObjectModel.Section s) { var paragraph = s.AddParagraph(); // add text from paragraph etc return paragraph; } } public class TableRenderer : IPdfRenderer<MigraDoc.DocumentObjectModel.Tables.Table> { BusinessEntities.PDF.Table table; public TableRenderer(BusinessEntities.PDF.Table t) { table =t; } public MigraDoc.DocumentObjectModel.Tables.Table Render(Section obj) { var table = obj.AddTable(); //fill table based on table } } I want to create a PDF page as : var document = new Document(); var section = document.AddSection();// section is a page in pdf var page = GetPage(1); // get a page from business classes foreach (var content in page.Content) { //var renderer = createRenderer(content); // // get Renderer based on Business type ?? // renderer.Render(section) } For createRenderer() i can use switch case/dictionary and return type. How can i get/create the renderer generically based on type ? How can I use factory or abstract factory here? Or which design pattern better suits this problem?

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• translating specifications into query predicates

  - by Jeroen

  I'm trying to find a nice and elegant way to query database content based on DDD "specifications". In domain driven design, a specification is used to check if some object, also known as the candidate, is compliant to a (domain specific) requirement. For example, the specification 'IsTaskDone' goes like: class IsTaskDone extends Specification<Task> { boolean isSatisfiedBy(Task candidate) { return candidate.isDone(); } } The above specification can be used for many purposes, e.g. it can be used to validate if a task has been completed, or to filter all completed tasks from a collection. However, I want to re-use this, nice, domain related specification to query on the database. Of course, the easiest solution would be to retrieve all entities of our desired type from the database, and filter that list in-memory by looping and removing non-matching entities. But clearly that would not be optimal for performance, especially when the entity count in our db increases. Proposal So my idea is to create a 'ConversionManager' that translates my specification into a persistence technique specific criteria, think of the JPA predicate class. The services looks as follows: public interface JpaSpecificationConversionManager { <T> Predicate getPredicateFor(Specification<T> specification, Root<T> root, CriteriaQuery<?> cq, CriteriaBuilder cb); JpaSpecificationConversionManager registerConverter(JpaSpecificationConverter<?, ?> converter); } By using our manager, the users can register their own conversion logic, isolating the domain related specification from persistence specific logic. To minimize the configuration of our manager, I want to use annotations on my converter classes, allowing the manager to automatically register those converters. JPA repository implementations could then use my manager, via dependency injection, to offer a find by specification method. Providing a find by specification should drastically reduce the number of methods on our repository interface. In theory, this all sounds decent, but I feel like I'm missing something critical. What do you guys think of my proposal, does it comply to the DDD way of thinking? Or is there already a framework that does something identical to what I just described?

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• Is it ok to dynamic cast "this" as a return value?

  - by Panayiotis Karabassis

  This is more of a design question. I have a template class, and I want to add extra methods to it depending on the template type. To practice the DRY principle, I have come up with this pattern (definitions intentionally omitted): template <class T> class BaseVector: public boost::array<T, 3> { protected: BaseVector<T>(const T x, const T y, const T z); public: bool operator == (const Vector<T> &other) const; Vector<T> operator + (const Vector<T> &other) const; Vector<T> operator - (const Vector<T> &other) const; Vector<T> &operator += (const Vector<T> &other) { (*this)[0] += other[0]; (*this)[1] += other[1]; (*this)[2] += other[2]; return *dynamic_cast<Vector<T> * const>(this); } } template <class T> class Vector : public BaseVector<T> { public: Vector<T>(const T x, const T y, const T z) : BaseVector<T>(x, y, z) { } }; template <> class Vector<double> : public BaseVector<double> { public: Vector<double>(const double x, const double y, const double z); Vector<double>(const Vector<int> &other); double norm() const; }; I intend BaseVector to be nothing more than an implementation detail. This works, but I am concerned about operator+=. My question is: is the dynamic cast of the this pointer a code smell? Is there a better way to achieve what I am trying to do (avoid code duplication, and unnecessary casts in the user code)? Or am I safe since, the BaseVector constructor is private?

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• Grid sorting with persistent master sort

  - by MikeWyatt

  I have a UI with a grid. Each record in the grid is sorted by a "master" sort column, let's call it a page number. Each record is a story in a magazine. I want the user to be able to drag and drop a record to a new position in the grid and automatically update the page number field to reflect the updated position. Easy enough, right? Now imagine that I also want to have the grid sortable by any other column (story title, section, author name, etc.). How does the drag and drop operation work now? Revert to page number sort during or after the drag and drop operation? This could confuse the user (why did my sort just change?). It would also result in arbitrary row positioning. Would the story now be before the row that was after it when the user dropped it? Or, would it be after the row that was before it? Those rows may now be widely separated after the master order sort. Disable the drag and drop feature if the grid isn't currently sorted by the page number? This would be easy, but the user might wonder why he can't drag and drop at certain times. Knowing to first sort by page number may not be very intuitive. Let the user rearrange his rows, but not make any changes to the page number? Require the user to enter a "Arrange Stories" mode, in which the grid sort is temporarily switched to page number and drag and drop is enabled? They would then exit the mode, and the previous sort would be reapplied. The big difference between this and the second option is that it would be more explicit than simply clicking on a column header. Any other ideas, or reasons why one of the above is the way to go? EDIT I'd like to point out that any of the above is technically possible, and easy to implement. My question is design-related. What is the most intuitive way to solve this problem, from the user's perspective?

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• Foreign key pointing to different tables

  - by Álvaro G. Vicario

  I'm implementing a table per subclass design I discussed in a previous question. It's a product database where products can have very different attributes depending on their type, but attributes are fixed for each type and types are not manageable at all. I have a master table that holds common attributes: product_type ============ product_type_id INT product_type_name VARCHAR E.g.: 1 'Magazine' 2 'Web site' product ======= product_id INT product_name VARCHAR product_type_id INT -> Foreign key to product_type.product_type_id valid_since DATETIME valid_to DATETIME E.g. 1 'Foo Magazine' 1 '1998-12-01' NULL 2 'Bar Weekly Review' 1 '2005-01-01' NULL 3 'E-commerce App' 2 '2009-10-15' NULL 4 'CMS' 2 '2010-02-01' NULL ... and one subtable for each product type: item_magazine ============= item_magazine_id INT title VARCHAR product_id INT -> Foreign key to product.product_id issue_number INT pages INT copies INT close_date DATETIME release_date DATETIME E.g. 1 'Foo Magazine Regular Issue' 1 89 52 150000 '2010-06-25' '2010-06-31' 2 'Foo Magazine Summer Special' 1 90 60 175000 '2010-07-25' '2010-07-31' 3 'Bar Weekly Review Regular Issue' 2 12 16 20000 '2010-06-01' '2010-06-02' item_web_site ============= item_web_site_id INT name VARCHAR product_id INT -> Foreign key to product.product_id bandwidth INT hits INT date_from DATETIME date_to DATETIME E.g. 1 'The Carpet Store' 3 10 90000 '2010-06-01' NULL 2 'Penauts R Us' 3 20 180000 '2010-08-01' NULL 3 'Springfield Cattle Fair' 4 15 150000 '2010-05-01' '2010-10-31' Now I want to add some fees that relate to one specific item. Since there are very little subtypes, it's feasible to do this: fee === fee_id INT fee_description VARCHAR item_magazine_id INT -> Foreign key to item_magazine.item_magazine_id item_web_site_id INT -> Foreign key to item_web_site.item_web_site_id net_price DECIMAL E.g.: 1 'Front cover' 2 NULL 1999.99 2 'Half page' 2 NULL 500.00 3 'Square banner' NULL 3 790.50 4 'Animation' NULL 3 2000.00 I have tight foreign keys to handle cascaded editions and I presume I can add a constraint so only one of the IDs is NOT NULL. However, my intuition suggests that it would be cleaner to get rid of the item_WHATEVER_id columns and keep a separate table: fee_to_item =========== fee_id INT -> Foreign key to fee.fee_id product_id INT -> Foreign key to product.product_id item_id INT -> ??? But I can't figure out how to create foreign keys on item_id since the source table varies depending on product_id. Should I stick to my original idea?

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• Are there any modern GUI toolkits which implement a heirarchical menu buffer zone?

  - by scomar

  In Bruce Tognazzini's quiz on Fitt's Law, the question discussing the bottleneck in the hierarchical menu (as used in almost every modern desktop UI), talks about his design for the original Mac: The bottleneck is the passage between the first-level menu and the second-level menu. Users first slide the mouse pointer down to the category menu item. Then, they must carefully slide the mouse directly across (horizontally) in order to move the pointer into the secondary menu. The engineer who originally designed hierarchicals apparently had his forearm mounted on a track so that he could move it perfectly in a horizontal direction without any vertical component. Most of us, however, have our forarms mounted on a pivot we like to call our elbow. That means that moving our hand describes an arc, rather than a straight line. Demanding that pivoted people move a mouse pointer along in a straight line horizontally is just wrong. We are naturally going to slip downward even as we try to slide sideways. When we are not allowed to slip downward, the menu we're after is going to slam shut just before we get there. The Windows folks tried to overcome the pivot problem with a hack: If they see the user move down into range of the next item on the primary menu, they don't instantly close the second-level menu. Instead, they leave it open for around a half second, so, if users are really quick, they can be inaccurate but still get into the second-level menu before it slams shut. Unfortunately, people's reactions to heightened chance of error is to slow down, rather than speed up, a well-established phenomenon. Therefore, few users will ever figure out that moving faster could solve their problem. Microsoft's solution is exactly wrong. When I specified the Mac hierarchical menu algorthm in the mid-'80s, I called for a buffer zone shaped like a <, so that users could make an increasingly-greater error as they neared the hierarchical without fear of jumping to an unwanted menu. As long as the user's pointer was moving a few pixels over for every one down, on average, the menu stayed open, no matter how slow they moved. (Cancelling was still really easy; just deliberately move up or down.) This just blew me away! Such a simple idea which would result in a huge improvement in usability. I'm sure I'm not the only one who regularly has the next level of a menu slam shut because I don't move the mouse pointer in a perfectly horizontal line. So my question is: Are there any modern UI toolkits which implement this brilliant idea of a < shaped buffer zone in hierarchical menus? And if not, why not?!

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• When does logic belong in the Business Object/Entity, and when does it belong in a Service?

  - by Casey

  In trying to understand Domain Driven Design I keep returning to a question that I can't seem to definitively answer. How do you determine what logic belongs to a Domain entity, and what logic belongs to a Domain Service? Example: We have an Order class for an online store. This class is an entity and an aggregate root (it contains OrderItems). Public Class Order:IOrder { Private List<IOrderItem> OrderItems Public Order(List<IOrderItem>) { OrderItems = List<IOrderItem> } Public Decimal CalculateTotalItemWeight() //This logic seems to belong in the entity. { Decimal TotalWeight = 0 foreach(IOrderItem OrderItem in OrderItems) { TotalWeight += OrderItem.Weight } return TotalWeight } } I think most people would agree that CalculateTotalItemWeight belongs on the entity. However, at some point we have to ship this order to the customer. To accomplish this we need to do two things: 1) Determine the postage rate necessary to ship this order. 2) Print a shipping label after determining the postage rate. Both of these actions will require dependencies that are outside the Order entity, such as an external webservice to retrieve postage rates. How should we accomplish these two things? I see a few options: 1) Code the logic directly in the domain entity, like CalculateTotalItemWeight. We then call: Order.GetPostageRate Order.PrintLabel 2) Put the logic in a service that accepts IOrder. We then call: PostageService.GetPostageRate(Order) PrintService.PrintLabel(Order) 3) Create a class for each action that operates on an Order, and pass an instance of that class to the Order through Constructor Injection (this is a variation of option 1 but allows reuse of the RateRetriever and LabelPrinter classes): Public Class Order:IOrder { Private List<IOrderItem> OrderItems Private RateRetriever _Retriever Private LabelPrinter _Printer Public Order(List<IOrderItem>, RateRetriever Retriever, LabelPrinter Printer) { OrderItems = List<IOrderItem> _Retriever = Retriever _Printer = Printer } Public Decimal GetPostageRate { _Retriever.GetPostageRate(this) } Public void PrintLabel { _Printer.PrintLabel(this) } } Which one of these methods do you choose for this logic, if any? What is the reasoning behind your choice? Most importantly, is there a set of guidelines that led you to your choice?

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• Partitioned Repository for WebCenter Content using Oracle Database 11g

  - by Adao Junior

  One of the biggest challenges for content management solutions is related to the storage management due the high volumes of the unstoppable growing of information. Even if you have storage appliances and a lot of terabytes, thinks like backup, compression, deduplication, storage relocation, encryption, availability could be a nightmare. One standard option that you have with the Oracle WebCenter Content is to store data to the database. And the Oracle Database allows you leverage features like compression, deduplication, encryption and seamless backup. But with a huge volume, the challenge is passed to the DBA to keep the WebCenter Content Database up and running. One solution is the use of DB partitions for your content repository, but what are the implications of this? Can I fit this with my business requirements? Well, yes. It’s up to you how you will manage that, you just need a good plan. During you “storage brainstorm plan” take in your mind what you need, such as storage petabytes of documents? You need everything on-line? There’s a way to logically separate the “good content” from the “legacy content”? The first thing that comes to my mind is to use the creation date of the document, but you need to remember that this document could receive a lot of revisions and maybe you can consider the revision creation date. Your plan can have also complex rules like per Document Type or per a custom metadata like department or an hybrid per date, per DocType and an specific virtual folder. Extrapolation the use, you can have your repository distributed in different servers, different disks, different disk types (Such as ssds, sas, sata, tape,…), separated accordingly your business requirements, separating the “hot” content from the legacy and easily matching your compliance requirements. If you think to use by revision, the simple way is to consider the dId, that is the sequential unique id for every content created using the WebCenter Content or the dLastModified that is the date field of the FileStorage table that contains the date of inclusion of the content to the DB Table using SecureFiles. Using the scenario of partitioned repository using an hierarchical separation by date, we will transform the FileStorage table in an partitioned table using  “Partition by Range” of the dLastModified column (You can use the dId or a join with other tables for other metadata such as dDocType, Security, etc…). The test scenario bellow covers: Previous existent data on the JDBC Storage to be migrated to the new partitioned JDBC Storage Partition by Date Automatically generation of new partitions based on a pre-defined interval (Available only with Oracle Database 11g+) Deduplication and Compression for legacy data Oracle WebCenter Content 11g PS5 (Could present some customizations that do not affect the test scenario) For the test case you need some data stored using JDBC Storage to be the “legacy” data. If you do not have done before, just create an Storage rule pointed to the JDBC Storage: Enable the metadata StorageRule in the UI and upload some documents using this rule. For this test case you can run using the schema owner or an dba user. We will use the schema owner TESTS_OCS. I can’t forgot to tell that this is just a test and you should do a proper backup of your environment. When you use the schema owner, you need some privileges, using the dba user grant the privileges needed: REM Grant privileges required for online redefinition. GRANT EXECUTE ON DBMS_REDEFINITION TO TESTS_OCS; GRANT ALTER ANY TABLE TO TESTS_OCS; GRANT DROP ANY TABLE TO TESTS_OCS; GRANT LOCK ANY TABLE TO TESTS_OCS; GRANT CREATE ANY TABLE TO TESTS_OCS; GRANT SELECT ANY TABLE TO TESTS_OCS; REM Privileges required to perform cloning of dependent objects. GRANT CREATE ANY TRIGGER TO TESTS_OCS; GRANT CREATE ANY INDEX TO TESTS_OCS; In our test scenario we will separate the content as Legacy, Day1, Day2, Day3 and Future. This last one will partitioned automatically using 3 tablespaces in a round robin mode. In a real scenario the partition rule could be per month, per year or any rule that you choose. Table spaces for the test scenario: CREATE TABLESPACE TESTS_OCS_PART_LEGACY DATAFILE 'tests_ocs_part_legacy.dat' SIZE 500K AUTOEXTEND ON NEXT 500K MAXSIZE UNLIMITED; CREATE TABLESPACE TESTS_OCS_PART_DAY1 DATAFILE 'tests_ocs_part_day1.dat' SIZE 500K AUTOEXTEND ON NEXT 500K MAXSIZE UNLIMITED; CREATE TABLESPACE TESTS_OCS_PART_DAY2 DATAFILE 'tests_ocs_part_day2.dat' SIZE 500K AUTOEXTEND ON NEXT 500K MAXSIZE UNLIMITED; CREATE TABLESPACE TESTS_OCS_PART_DAY3 DATAFILE 'tests_ocs_part_day3.dat' SIZE 500K AUTOEXTEND ON NEXT 500K MAXSIZE UNLIMITED; CREATE TABLESPACE TESTS_OCS_PART_ROUND_ROBIN_A 'tests_ocs_part_round_robin_a.dat' DATAFILE SIZE 500K AUTOEXTEND ON NEXT 500K MAXSIZE UNLIMITED; CREATE TABLESPACE TESTS_OCS_PART_ROUND_ROBIN_B 'tests_ocs_part_round_robin_b.dat' DATAFILE SIZE 500K AUTOEXTEND ON NEXT 500K MAXSIZE UNLIMITED; CREATE TABLESPACE TESTS_OCS_PART_ROUND_ROBIN_C 'tests_ocs_part_round_robin_c.dat' DATAFILE SIZE 500K AUTOEXTEND ON NEXT 500K MAXSIZE UNLIMITED; Before start, gather optimizer statistics on the actual FileStorage table: EXEC DBMS_STATS.GATHER_TABLE_STATS(USER, 'FileStorage', cascade => TRUE); Now check if is possible execute the redefinition process: EXEC DBMS_REDEFINITION.CAN_REDEF_TABLE('TESTS_OCS', 'FileStorage',DBMS_REDEFINITION.CONS_USE_PK); If no errors messages, you are good to go. Create a Partitioned Interim FileStorage table. You need to create a new table with the partition information to act as an interim table: CREATE TABLE FILESTORAGE_Part ( DID NUMBER(*,0) NOT NULL ENABLE, DRENDITIONID VARCHAR2(30 CHAR) NOT NULL ENABLE, DLASTMODIFIED TIMESTAMP (6), DFILESIZE NUMBER(*,0), DISDELETED VARCHAR2(1 CHAR), BFILEDATA BLOB ) LOB (BFILEDATA) STORE AS SECUREFILE ( ENABLE STORAGE IN ROW NOCACHE LOGGING KEEP_DUPLICATES NOCOMPRESS ) PARTITION BY RANGE (DLASTMODIFIED) INTERVAL (NUMTODSINTERVAL(1,'DAY')) STORE IN (TESTS_OCS_PART_ROUND_ROBIN_A, TESTS_OCS_PART_ROUND_ROBIN_B, TESTS_OCS_PART_ROUND_ROBIN_C) ( PARTITION FILESTORAGE_PART_LEGACY VALUES LESS THAN (TO_DATE('05-APR-2012 12.00.00 AM', 'DD-MON-YYYY HH.MI.SS AM')) TABLESPACE TESTS_OCS_PART_LEGACY LOB (BFILEDATA) STORE AS SECUREFILE ( TABLESPACE TESTS_OCS_PART_LEGACY RETENTION NONE DEDUPLICATE COMPRESS HIGH ), PARTITION FILESTORAGE_PART_DAY1 VALUES LESS THAN (TO_DATE('06-APR-2012 07.25.00 PM', 'DD-MON-YYYY HH.MI.SS AM')) TABLESPACE TESTS_OCS_PART_DAY1 LOB (BFILEDATA) STORE AS SECUREFILE ( TABLESPACE TESTS_OCS_PART_DAY1 RETENTION AUTO KEEP_DUPLICATES COMPRESS ), PARTITION FILESTORAGE_PART_DAY2 VALUES LESS THAN (TO_DATE('06-APR-2012 07.55.00 PM', 'DD-MON-YYYY HH.MI.SS AM')) TABLESPACE TESTS_OCS_PART_DAY2 LOB (BFILEDATA) STORE AS SECUREFILE ( TABLESPACE TESTS_OCS_PART_DAY2 RETENTION AUTO KEEP_DUPLICATES NOCOMPRESS ), PARTITION FILESTORAGE_PART_DAY3 VALUES LESS THAN (TO_DATE('06-APR-2012 07.58.00 PM', 'DD-MON-YYYY HH.MI.SS AM')) TABLESPACE TESTS_OCS_PART_DAY3 LOB (BFILEDATA) STORE AS SECUREFILE ( TABLESPACE TESTS_OCS_PART_DAY3 RETENTION AUTO KEEP_DUPLICATES NOCOMPRESS ) ); After the creation you should see your partitions defined. Note that only the fixed range partitions have been created, none of the interval partition have been created. Start the redefinition process: BEGIN DBMS_REDEFINITION.START_REDEF_TABLE( uname => 'TESTS_OCS' ,orig_table => 'FileStorage' ,int_table => 'FileStorage_PART' ,col_mapping => NULL ,options_flag => DBMS_REDEFINITION.CONS_USE_PK ); END; This operation can take some time to complete, depending how many contents that you have and on the size of the table. Using the DBA user you can check the progress with this command: SELECT * FROM v$sesstat WHERE sid = 1; Copy dependent objects: DECLARE redefinition_errors PLS_INTEGER := 0; BEGIN DBMS_REDEFINITION.COPY_TABLE_DEPENDENTS( uname => 'TESTS_OCS' ,orig_table => 'FileStorage' ,int_table => 'FileStorage_PART' ,copy_indexes => DBMS_REDEFINITION.CONS_ORIG_PARAMS ,copy_triggers => TRUE ,copy_constraints => TRUE ,copy_privileges => TRUE ,ignore_errors => TRUE ,num_errors => redefinition_errors ,copy_statistics => FALSE ,copy_mvlog => FALSE ); IF (redefinition_errors > 0) THEN DBMS_OUTPUT.PUT_LINE('>>> FileStorage to FileStorage_PART temp copy Errors: ' || TO_CHAR(redefinition_errors)); END IF; END; With the DBA user, verify that there's no errors: SELECT object_name, base_table_name, ddl_txt FROM DBA_REDEFINITION_ERRORS; *Note that will show 2 lines related to the constrains, this is expected. Synchronize the interim table FileStorage_PART: BEGIN DBMS_REDEFINITION.SYNC_INTERIM_TABLE( uname => 'TESTS_OCS', orig_table => 'FileStorage', int_table => 'FileStorage_PART'); END; Gather statistics on the new table: EXEC DBMS_STATS.GATHER_TABLE_STATS(USER, 'FileStorage_PART', cascade => TRUE); Complete the redefinition: BEGIN DBMS_REDEFINITION.FINISH_REDEF_TABLE( uname => 'TESTS_OCS', orig_table => 'FileStorage', int_table => 'FileStorage_PART'); END; During the execution the FileStorage table is locked in exclusive mode until finish the operation. After the last command the FileStorage table is partitioned. If you have contents out of the range partition, you should see the new partitions created automatically, not generating an error if you “forgot” to create all the future ranges. You will see something like: You now can drop the FileStorage_PART table: border-bottom-width: 1px; border-bottom-style: solid; text-align: left; border-left-color: silver; border-left-width: 1px; border-left-style: solid; padding-bottom: 4px; line-height: 12pt; background-color: #f4f4f4; margin-top: 20px; margin-right: 0px; margin-bottom: 10px; margin-left: 0px; padding-left: 4px; width: 97.5%; padding-right: 4px; font-family: 'Courier New', Courier, monospace; direction: ltr; max-height: 200px; font-size: 8pt; overflow-x: auto; overflow-y: auto; border-top-color: silver; border-top-width: 1px; border-top-style: solid; cursor: text; border-right-color: silver; border-right-width: 1px; border-right-style: solid; padding-top: 4px; " id="codeSnippetWrapper"> DROP TABLE FileStorage_PART PURGE; To check the FileStorage table is valid and is partitioned, use the command: SELECT num_rows,partitioned FROM user_tables WHERE table_name = 'FILESTORAGE'; You can list the contents of the FileStorage table in a specific partition, per example: SELECT * FROM FileStorage PARTITION (FILESTORAGE_PART_LEGACY) Some useful commands that you can use to check the partitions, note that you need to run using a DBA user: SELECT * FROM DBA_TAB_PARTITIONS WHERE table_name = 'FILESTORAGE';   SELECT * FROM DBA_TABLESPACES WHERE tablespace_name like 'TESTS_OCS%'; After the redefinition process complete you have a new FileStorage table storing all content that has the Storage rule pointed to the JDBC Storage and partitioned using the rule set during the creation of the temporary interim FileStorage_PART table. At this point you can test the WebCenter Content downloading the documents (Original and Renditions). Note that the content could be already in the cache area, take a look in the weblayout directory to see if a file with the same id is there, then click on the web rendition of your test file and see if have created the file and you can open, this means that is all working. The redefinition process can be repeated many times, this allow you test what the better layout, over and over again. Now some interesting maintenance actions related to the partitions: Make an tablespace read only. No issues viewing, the WebCenter Content do not alter the revisions When try to delete an content that is part of an read only tablespace, an error will occurs and the document will not be deleted The only way to prevent errors today is creating an custom component that checks the partitions and if you have an document in an “Read Only” repository, execute the deletion process of the metadata and mark the document to be deleted on the next db maintenance, like a new redefinition. Take an tablespace off-line for archiving purposes or any other reason. When you try open an document that is included in this tablespace will receive an error that was unable to retrieve the content, but the others online tablespaces are not affected. Same behavior when deleting documents. Again, an custom component is the solution. If you have an document “out of range”, the component can show an message that the repository for that document is offline. This can be extended to a option to the user to request to put online again. Moving some legacy content to an offline repository (table) using the Exchange option to move the content from one partition to a empty nonpartitioned table like FileStorage_LEGACY. Note that this option will remove the registers from the FileStorage and will not be able to open the stored content. You always need to keep in mind the indexes and constrains. An redefinition separating the original content (vault) from the renditions and separate by date ate the same time. This could be an option for DAM environments that want to have an special place for the renditions and put the original files in a storage with less performance. The process will be the same, you just need to change the script of the interim table to use composite partitioning. Will be something like: CREATE TABLE FILESTORAGE_RenditionPart ( DID NUMBER(*,0) NOT NULL ENABLE, DRENDITIONID VARCHAR2(30 CHAR) NOT NULL ENABLE, DLASTMODIFIED TIMESTAMP (6), DFILESIZE NUMBER(*,0), DISDELETED VARCHAR2(1 CHAR), BFILEDATA BLOB ) LOB (BFILEDATA) STORE AS SECUREFILE ( ENABLE STORAGE IN ROW NOCACHE LOGGING KEEP_DUPLICATES NOCOMPRESS ) PARTITION BY LIST (DRENDITIONID) SUBPARTITION BY RANGE (DLASTMODIFIED) ( PARTITION Vault VALUES ('primaryFile') ( SUBPARTITION FILESTORAGE_VAULT_LEGACY VALUES LESS THAN (TO_DATE('05-APR-2012 12.00.00 AM', 'DD-MON-YYYY HH.MI.SS AM')) LOB (BFILEDATA) STORE AS SECUREFILE , SUBPARTITION FILESTORAGE_VAULT_DAY1 VALUES LESS THAN (TO_DATE('06-APR-2012 07.25.00 PM', 'DD-MON-YYYY HH.MI.SS AM')) LOB (BFILEDATA) STORE AS SECUREFILE , SUBPARTITION FILESTORAGE_VAULT_DAY2 VALUES LESS THAN (TO_DATE('06-APR-2012 07.55.00 PM', 'DD-MON-YYYY HH.MI.SS AM')) LOB (BFILEDATA) STORE AS SECUREFILE , SUBPARTITION FILESTORAGE_VAULT_DAY3 VALUES LESS THAN (TO_DATE('06-APR-2012 07.58.00 PM', 'DD-MON-YYYY HH.MI.SS AM')) LOB (BFILEDATA) STORE AS SECUREFILE , SUBPARTITION FILESTORAGE_VAULT_FUTURE VALUES LESS THAN (MAXVALUE) ) ,PARTITION WebLayout VALUES ('webViewableFile') ( SUBPARTITION FILESTORAGE_WEBLAYOUT_LEGACY VALUES LESS THAN (TO_DATE('05-APR-2012 12.00.00 AM', 'DD-MON-YYYY HH.MI.SS AM')) LOB (BFILEDATA) STORE AS SECUREFILE , SUBPARTITION FILESTORAGE_WEBLAYOUT_DAY1 VALUES LESS THAN (TO_DATE('06-APR-2012 07.25.00 PM', 'DD-MON-YYYY HH.MI.SS AM')) LOB (BFILEDATA) STORE AS SECUREFILE , SUBPARTITION FILESTORAGE_WEBLAYOUT_DAY2 VALUES LESS THAN (TO_DATE('06-APR-2012 07.55.00 PM', 'DD-MON-YYYY HH.MI.SS AM')) LOB (BFILEDATA) STORE AS SECUREFILE , SUBPARTITION FILESTORAGE_WEBLAYOUT_DAY3 VALUES LESS THAN (TO_DATE('06-APR-2012 07.58.00 PM', 'DD-MON-YYYY HH.MI.SS AM')) LOB (BFILEDATA) STORE AS SECUREFILE , SUBPARTITION FILESTORAGE_WEBLAYOUT_FUTURE VALUES LESS THAN (MAXVALUE) ) ,PARTITION Special VALUES ('Special') ( SUBPARTITION FILESTORAGE_SPECIAL_LEGACY VALUES LESS THAN (TO_DATE('05-APR-2012 12.00.00 AM', 'DD-MON-YYYY HH.MI.SS AM')) LOB (BFILEDATA) STORE AS SECUREFILE , SUBPARTITION FILESTORAGE_SPECIAL_DAY1 VALUES LESS THAN (TO_DATE('06-APR-2012 07.25.00 PM', 'DD-MON-YYYY HH.MI.SS AM')) LOB (BFILEDATA) STORE AS SECUREFILE , SUBPARTITION FILESTORAGE_SPECIAL_DAY2 VALUES LESS THAN (TO_DATE('06-APR-2012 07.55.00 PM', 'DD-MON-YYYY HH.MI.SS AM')) LOB (BFILEDATA) STORE AS SECUREFILE , SUBPARTITION FILESTORAGE_SPECIAL_DAY3 VALUES LESS THAN (TO_DATE('06-APR-2012 07.58.00 PM', 'DD-MON-YYYY HH.MI.SS AM')) LOB (BFILEDATA) STORE AS SECUREFILE , SUBPARTITION FILESTORAGE_SPECIAL_FUTURE VALUES LESS THAN (MAXVALUE) ) )ENABLE ROW MOVEMENT; The next post related to partitioned repository will come with an sample component to handle the possible exceptions when you need to take off line an tablespace/partition or move to another place. Also, we can include some integration to the Retention Management and Records Management. Another subject related to partitioning is the ability to create an FileStore Provider pointed to a different database, raising the level of the distributed storage vs. performance. Let us know if this is important to you or you have an use case not listed, leave a comment. Cross-posted on the blog.ContentrA.com

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• Contructor parameters for dependent classes with Unity Framework

  - by Onisemus

  I just started using the Unity Application Block to try to decouple my classes and make it easier for unit testing. I ran into a problem though that I'm not sure how to get around. Looked through the documentation and did some Googling but I'm coming up dry. Here's the situation: I have a facade-type class which is a chat bot. It is a singleton class which handles all sort of secondary classes and provides a central place to launch and configure the bot. I also have a class called AccessManager which, well, manages access to bot commands and resources. Boiled down to the essence, I have the classes set up like so. public class Bot { public string Owner { get; private set; } public string WorkingDirectory { get; private set; } private IAccessManager AccessManager; private Bot() { // do some setup // LoadConfig sets the Owner & WorkingDirectory variables LoadConfig(); // init the access mmanager AccessManager = new MyAccessManager(this); } public static Bot Instance() { // singleton code } ... } And the AccessManager class: public class MyAccessManager : IAccessManager { private Bot botReference; public MyAccesManager(Bot botReference) { this.botReference = botReference; SetOwnerAccess(botReference.Owner); } private void LoadConfig() { string configPath = Path.Combine( botReference.WorkingDirectory, "access.config"); // do stuff to read from config file } ... } I would like to change this design to use the Unity Application Block. I'd like to use Unity to generate the Bot singleton and to load the AccessManager interface in some sort of bootstrapping method that runs before anything else does. public static void BootStrapSystem() { IUnityContainer container = new UnityContainer(); // create new bot instance Bot newBot = Bot.Instance(); // register bot instance container.RegisterInstance<Bot>(newBot); // register access manager container.RegisterType<IAccessManager,MyAccessManager>(newBot); } And when I want to get a reference to the Access Manager inside the Bot constructor I can just do: IAcessManager accessManager = container.Resolve<IAccessManager>(); And elsewhere in the system to get a reference to the Bot singleton: // do this Bot botInstance = container.Resolve<Bot>(); // instead of this Bot botInstance = Bot.Instance(); The problem is the method BootStrapSystem() is going to blow up. When I create a bot instance it's going to try to resolve IAccessManager but won't be able to because I haven't registered the types yet (that's the next line). But I can't move the registration in front of the Bot creation because as part of the registration I need to pass the Bot as a parameter! Circular dependencies!! Gah!!! This indicates to me I have a flaw in the way I have this structured. But how do I fix it? Help!!

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• Domain Validation in a CQRS architecture

  - by Jupaol

  Basically I want to know if there is a better way to validate my domain entities. This is how I am planning to do it but I would like your opinion The first approach I considered was: class Customer : EntityBase<Customer> { public void ChangeEmail(string email) { if(string.IsNullOrWhitespace(email)) throw new DomainException(“...”); if(!email.IsEmail()) throw new DomainException(); if(email.Contains(“@mailinator.com”)) throw new DomainException(); } } I actually do not like this validation because even when I am encapsulating the validation logic in the correct entity, this is violating the Open/Close principle (Open for extension but Close for modification) and I have found that violating this principle, code maintenance becomes a real pain when the application grows up in complexity. Why? Because domain rules change more often than we would like to admit, and if the rules are hidden and embedded in an entity like this, they are hard to test, hard to read, hard to maintain but the real reason why I do not like this approach is: if the validation rules change, I have to come and edit my domain entity. This has been a really simple example but in RL the validation could be more complex So following the philosophy of Udi Dahan, making roles explicit, and the recommendation from Eric Evans in the blue book, the next try was to implement the specification pattern, something like this class EmailDomainIsAllowedSpecification : IDomainSpecification<Customer> { private INotAllowedEmailDomainsResolver invalidEmailDomainsResolver; public bool IsSatisfiedBy(Customer customer) { return !this.invalidEmailDomainsResolver.GetInvalidEmailDomains().Contains(customer.Email); } } But then I realize that in order to follow this approach I had to mutate my entities first in order to pass the value being valdiated, in this case the email, but mutating them would cause my domain events being fired which I wouldn’t like to happen until the new email is valid So after considering these approaches, I came out with this one, since I am going to implement a CQRS architecture: class EmailDomainIsAllowedValidator : IDomainInvariantValidator<Customer, ChangeEmailCommand> { public void IsValid(Customer entity, ChangeEmailCommand command) { if(!command.Email.HasValidDomain()) throw new DomainException(“...”); } } Well that’s the main idea, the entity is passed to the validator in case we need some value from the entity to perform the validation, the command contains the data coming from the user and since the validators are considered injectable objects they could have external dependencies injected if the validation requires it. Now the dilemma, I am happy with a design like this because my validation is encapsulated in individual objects which brings many advantages: easy unit test, easy to maintain, domain invariants are explicitly expressed using the Ubiquitous Language, easy to extend, validation logic is centralized and validators can be used together to enforce complex domain rules. And even when I know I am placing the validation of my entities outside of them (You could argue a code smell - Anemic Domain) but I think the trade-off is acceptable But there is one thing that I have not figured out how to implement it in a clean way. How should I use this components... Since they will be injected, they won’t fit naturally inside my domain entities, so basically I see two options: Pass the validators to each method of my entity Validate my objects externally (from the command handler) I am not happy with the option 1 so I would explain how I would do it with the option 2 class ChangeEmailCommandHandler : ICommandHandler<ChangeEmailCommand> { public void Execute(ChangeEmailCommand command) { private IEnumerable<IDomainInvariantValidator> validators; // here I would get the validators required for this command injected, and in here I would validate them, something like this using (var t = this.unitOfWork.BeginTransaction()) { var customer = this.unitOfWork.Get<Customer>(command.CustomerId); this.validators.ForEach(x =. x.IsValid(customer, command)); // here I know the command is valid // the call to ChangeEmail will fire domain events as needed customer.ChangeEmail(command.Email); t.Commit(); } } } Well this is it. Can you give me your thoughts about this or share your experiences with Domain entities validation EDIT I think it is not clear from my question, but the real problem is: Hiding the domain rules has serious implications in the future maintainability of the application, and also domain rules change often during the life-cycle of the app. Hence implementing them with this in mind would let us extend them easily. Now imagine in the future a rules engine is implemented, if the rules are encapsulated outside of the domain entities, this change would be easier to implement

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• How to generate a Program template by generating an abstract class

  - by Byron-Lim Timothy Steffan

  i have the following problem. The 1st step is to implement a program, which follows a specific protocol on startup. Therefore, functions as onInit, onConfigRequest, etc. will be necessary. (These are triggered e.g. by incoming message on a TCP Port) My goal is to generate a class for example abstract one, which has abstract functions as onInit(), etc. A programmer should just inherit from this base class and should merely override these abstract functions of the base class. The rest as of the protocol e.g. should be simply handled in the background (using the code of the base class) and should not need to appear in the programmers code. What is the correct design strategy for such tasks? and how do I deal with, that the static main method is not inheritable? What are the key-tags for this problem? (I have problem searching for a solution since I lack clear statements on this problem) Goal is to create some sort of library/class, which - included in ones code - results in executables following the protocol. EDIT (new explanation): Okay let me try to explain more detailled: In this case programs should be clients within a client server architecture. We have a client server connection via TCP/IP. Each program needs to follow a specific protocol upon program start: As soon as my program starts and gets connected to the server it will receive an Init Message (TcpClient), when this happens it should trigger the function onInit(). (Should this be implemented by an event system?) After onInit() a acknowledgement message should be sent to the server. Afterwards there are some other steps as e.g. a config message from the server which triggers an onConfig and so on. Let's concentrate on the onInit function. The idea is, that onInit (and onConfig and so on) should be the only functions the programmer should edit while the overall protocol messaging is hidden for him. Therefore, I thought using an abstract class with the abstract methods onInit(), onConfig() in it should be the right thing. The static Main class I would like to hide, since within it e.g. there will be some part which connects to the tcp port, which reacts on the Init Message and which will call the onInit function. 2 problems here: 1. the static main class cant be inherited, isn it? 2. I cannot call abstract functions from the main class in the abstract master class. Let me give an Pseudo-example for my ideas: public abstract class MasterClass { static void Main(string[] args){ 1. open TCP connection 2. waiting for Init Message from server 3. onInit(); 4. Send Acknowledgement, that Init Routine has ended successfully 5. waiting for Config message from server 6..... } public abstract void onInit(); public abstract void onConfig(); } I hope you get the idea now! The programmer should afterwards inherit from this masterclass and merely need to edit the functions onInit and so on. Is this way possible? How? What else do you recommend for solving this? EDIT: The strategy ideo provided below is a good one! Check out my comment on that.

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• Advice on Factory Method

  - by heath

  Using php 5.2, I'm trying to use a factory to return a service to the controller. My request uri would be of the format www.mydomain.com/service/method/param1/param2/etc. My controller would then call a service factory using the token sent in the uri. From what I've seen, there are two main routes I could go with my factory. Single method: class ServiceFactory { public static function getInstance($token) { switch($token) { case 'location': return new StaticPageTemplateService('location'); break; case 'product': return new DynamicPageTemplateService('product'); break; case 'user' return new UserService(); break; default: return new StaticPageTemplateService($token); } } } or multiple methods: class ServiceFactory { public static function getLocationService() { return new StaticPageTemplateService('location'); } public static function getProductService() { return new DynamicPageTemplateService('product'); } public static function getUserService() { return new UserService(); } public static function getDefaultService($token) { return new StaticPageTemplateService($token); } } So, given this, I will have a handful of generic services in which I will pass that token (for example, StaticPageTemplateService and DynamicPageTemplateService) that will probably implement another factory method just like this to grab templates, domain objects, etc. And some that will be specific services (for example, UserService) which will be 1:1 to that token and not reused. So, this seems to be an ok approach (please give suggestions if it is not) for a small amount of services. But what about when, over time and my site grows, I end up with 100s of possibilities. This no longer seems like a good approach. Am I just way off to begin with or is there another design pattern that would be a better fit? Thanks. UPDATE: @JSprang - the token is actually sent in the uri like mydomain.com/location would want a service specific to loction and mydomain.com/news would want a service specific to news. Now, for a lot of these, the service will be generic. For instance, a lot of pages will call a StaticTemplatePageService in which the token is passed in to the service. That service in turn will grab the "location" template or "links" template and just spit it back out. Some will need DynamicTemplatePageService in which the token gets passed in, like "news" and that service will grab a NewsDomainObject, determine how to present it and spit that back out. Others, like "user" will be specific to a UserService in which it will have methods like Login, Logout, etc. So basically, the token will be used to determine which service is needed AND if it is generic service, that token will be passed to that service. Maybe token isn't the correct terminology but I hope you get the purpose. I wanted to use the factory so I can easily swap out which Service I need in case my needs change. I just worry that after the site grows larger (both pages and functionality) that the factory will become rather bloated. But I'm starting to feel like I just can't get away from storing the mappings in an array (like Stephen's solution). That just doesn't feel OOP to me and I was hoping to find something more elegant.

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• Configurable Values in Enum

  - by Omer Akhter

  I often use this design in my code to maintain configurable values. Consider this code: public enum Options { REGEX_STRING("Some Regex"), REGEX_PATTERN(Pattern.compile(REGEX_STRING.getString()), false), THREAD_COUNT(2), OPTIONS_PATH("options.config", false), DEBUG(true), ALWAYS_SAVE_OPTIONS(true), THREAD_WAIT_MILLIS(1000); Object value; boolean saveValue = true; private Options(Object value) { this.value = value; } private Options(Object value, boolean saveValue) { this.value = value; this.saveValue = saveValue; } public void setValue(Object value) { this.value = value; } public Object getValue() { return value; } public String getString() { return value.toString(); } public boolean getBoolean() { Boolean booleanValue = (value instanceof Boolean) ? (Boolean) value : null; if (value == null) { try { booleanValue = Boolean.valueOf(value.toString()); } catch (Throwable t) { } } // We want a NullPointerException here return booleanValue.booleanValue(); } public int getInteger() { Integer integerValue = (value instanceof Number) ? ((Number) value).intValue() : null; if (integerValue == null) { try { integerValue = Integer.valueOf(value.toString()); } catch (Throwable t) { } } return integerValue.intValue(); } public float getFloat() { Float floatValue = (value instanceof Number) ? ((Number) value).floatValue() : null; if (floatValue == null) { try { floatValue = Float.valueOf(value.toString()); } catch (Throwable t) { } } return floatValue.floatValue(); } public static void saveToFile(String path) throws IOException { FileWriter fw = new FileWriter(path); Properties properties = new Properties(); for (Options option : Options.values()) { if (option.saveValue) { properties.setProperty(option.name(), option.getString()); } } if (DEBUG.getBoolean()) { properties.list(System.out); } properties.store(fw, null); } public static void loadFromFile(String path) throws IOException { FileReader fr = new FileReader(path); Properties properties = new Properties(); properties.load(fr); if (DEBUG.getBoolean()) { properties.list(System.out); } Object value = null; for (Options option : Options.values()) { if (option.saveValue) { Class<?> clazz = option.value.getClass(); try { if (String.class.equals(clazz)) { value = properties.getProperty(option.name()); } else { value = clazz.getConstructor(String.class).newInstance(properties.getProperty(option.name())); } } catch (NoSuchMethodException ex) { Debug.log(ex); } catch (InstantiationException ex) { Debug.log(ex); } catch (IllegalAccessException ex) { Debug.log(ex); } catch (IllegalArgumentException ex) { Debug.log(ex); } catch (InvocationTargetException ex) { Debug.log(ex); } if (value != null) { option.setValue(value); } } } } } This way, I can save and retrieve values from files easily. The problem is that I don't want to repeat this code everywhere. Like as we know, enums can't be extended; so wherever I use this, I have to put all these methods there. I want only to declare the values and that if they should be persisted. No method definitions each time; any ideas?

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• What does a WinForm application need to be designed for usability, and be robust, clean, and profess

  - by msorens

  One of the principal problems impeding productivity in software implementation is the classic conundrum of “reinventing the wheel”. Of late I am a .NET developer and even the wonderful wizardry of .NET and Visual Studio covers only a portion of this challenging issue. Below I present my initial thoughts both on what is available and what should be available from .NET on a WinForm, focusing on good usability. That is, aspects of an application exposed to the user and making the user experience easier and/or better. (I do include a couple items not visible to the user because I feel strongly about them, such as diagnostics.) I invite you to contribute to these lists. LIST A: Components provided by .NET These are substantially complete components provided by .NET, i.e. those requiring at most trivial coding to use. “About” dialog -- add it with a couple clicks then customize. Persist settings across invocations -- .NET has the support; just use a few lines of code to glue them together. Migrate settings with a new version -- a powerful one, available with one line of code. Tooltips (and infotips) -- .NET includes just plain text tooltips; third-party libraries provide richer ones. Diagnostic support -- TraceSources, TraceListeners, and more are built-in. Internationalization -- support for tailoring your app to languages other than your own. LIST B: Components not provided by .NET These are not supplied at all by .NET or supplied only as rudimentary elements requiring substantial work to be realized. Splash screen -- a small window present during program startup with your logo, loading messages, etc. Tip of the day -- a mini-tutorial presented one bit at a time each time the user starts your app. Check for available updates -- facility to query a server to see if the user is running the latest version of your app, then provide a simple way to upgrade if a new version is found. Maximize to multiple monitors -- the canonical window allows you to maximize to a single monitor only; in my apps I allow maximizing across multiple monitors with a click. Taskbar notifier -- flash the taskbar when your backgrounded app has new info for the user. Options dialogs -- multi-page dialogs letting the user customize the app settings to his/her own preferences. Progress indicator -- for long running operations give the user feedback on how far there is left to go. Memory gauge -- an indicator (either absolute or percentage) of how much memory is used by your app. LIST C: Stylistic and/or tiny bits of functionality This list includes bits of functionality that are too tiny to merit being called a component, along with stylistic concerns (that admittedly do overlap with the Windows User Experience Interaction Guidelines). Design a form for resizing -- unless you are restricting your form to be a fixed size, use anchors and docking so that it does what is reasonable when enlarged or shrunk by the user. Set tab order on a form -- repeated tab presses by the user should advance from field to field in a logical order rather than the default order in which you added fields. Adjust controls to be aware of operating modes -- When starting a background operation with, for example, a “Go” button, disable that “Go” button until the operation completes. Provide access keys for all menu items (per UXGuide). Provide shortcut keys for commonly used menu items (per UXGuide). Set up some (global or important or common) shortcut keys without associating to menu items. Allow some menu items to be invoked with or without modifier keys (shift, control, alt) where the modifier key is useful to vary the operation slightly. Hook up Escape and Enter on child forms to do what is reasonable. Decorate any library classes with documentation-comments and attributes -- this allows Visual Studio to leverage them for Intellisense and property descriptions. Spell check your code! What else would you include?

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• referencing part of the composite primary key

  - by Zavael

  I have problems with setting the reference on database table. I have following structure: CREATE TABLE club( id INTEGER NOT NULL, name_short VARCHAR(30), name_full VARCHAR(70) NOT NULL ); CREATE UNIQUE INDEX club_uix ON club(id); ALTER TABLE club ADD CONSTRAINT club_pk PRIMARY KEY (id); CREATE TABLE team( id INTEGER NOT NULL, club_id INTEGER NOT NULL, team_name VARCHAR(30) ); CREATE UNIQUE INDEX team_uix ON team(id, club_id); ALTER TABLE team ADD CONSTRAINT team_pk PRIMARY KEY (id, club_id); ALTER TABLE team ADD FOREIGN KEY (club_id) REFERENCES club(id); CREATE TABLE person( id INTEGER NOT NULL, first_name VARCHAR(20), last_name VARCHAR(20) NOT NULL ); CREATE UNIQUE INDEX person_uix ON person(id); ALTER TABLE person ADD PRIMARY KEY (id); CREATE TABLE contract( person_id INTEGER NOT NULL, club_id INTEGER NOT NULL, wage INTEGER ); CREATE UNIQUE INDEX contract_uix on contract(person_id); ALTER TABLE contract ADD CONSTRAINT contract_pk PRIMARY KEY (person_id); ALTER TABLE contract ADD FOREIGN KEY (club_id) REFERENCES club(id); ALTER TABLE contract ADD FOREIGN KEY (person_id) REFERENCES person(id); CREATE TABLE player( person_id INTEGER NOT NULL, team_id INTEGER, height SMALLINT, weight SMALLINT ); CREATE UNIQUE INDEX player_uix on player(person_id); ALTER TABLE player ADD CONSTRAINT player_pk PRIMARY KEY (person_id); ALTER TABLE player ADD FOREIGN KEY (person_id) REFERENCES person(id); -- ALTER TABLE player ADD FOREIGN KEY (team_id) REFERENCES team(id); --this is not working It gives me this error: Error code -5529, SQL state 42529: a UNIQUE constraint does not exist on referenced columns: TEAM in statement [ALTER TABLE player ADD FOREIGN KEY (team_id) REFERENCES team(id)] As you can see, team table has composite primary key (club_id + id), the person references club through contract. Person has some common attributes for player and other staff types. One club can have multiple teams. Employed person has to have a contract with a club. Player (is the specification of person) - if emplyed - can be assigned to one of the club's teams. Is there better way to design my structure? I thought about excluding the club_id from team's primary key, but I would like to know if this is the only way. Thanks. UPDATE 1 I would like to have the id as team identification only within the club, so multiple teams can have equal id as long as they belong to different clubs. Is it possible? UPDATE 2 updated the naming convention as adviced by philip Some business rules to better understand the structure: One club can have 1..n teams (Main squad, Reserve squad, Youth squad or Team A, Team B... only team can play match, not club) One team belongs to one club only A player is type of person (other types (staff) are scouts, coaches etc so they do not need to belong to specific team, just to the club, if employed) Person can have 0..1 contract with 1 club (that means he is employed or unemployed) Player (if employed) belongs to one team of the club Now thinking about it - moving team_id from player to contract would solve my problem, and it could hold the condition "Player (if employed) belongs to one team of the club", but it would be redundant for other staff types. What do you think?

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• Do I must expose the aggregate children as public properties to implement the Persistence ignorance?

  - by xuehua

  Hi all, I'm very glad that i found this website recently, I've learned a lot from here. I'm from China, and my English is not so good. But i will try to express myself what i want to say. Recently, I've started learning about Domain Driven Design, and I'm very interested about it. And I plan to develop a Forum website using DDD. After reading lots of threads from here, I understood that persistence ignorance is a good practice. Currently, I have two questions about what I'm thinking for a long time. Should the domain object interact with repository to get/save data? If the domain object doesn't use repository, then how does the Infrastructure layer (like unit of work) know which domain object is new/modified/removed? For the second question. There's an example code: Suppose i have a user class: public class User { public Guid Id { get; set; } public string UserName { get; set; } public string NickName { get; set; } /// <summary> /// A Roles collection which represents the current user's owned roles. /// But here i don't want to use the public property to expose it. /// Instead, i use the below methods to implement. /// </summary> //public IList<Role> Roles { get; set; } private List<Role> roles = new List<Role>(); public IList<Role> GetRoles() { return roles; } public void AddRole(Role role) { roles.Add(role); } public void RemoveRole(Role role) { roles.Remove(role); } } Based on the above User class, suppose i get an user from the IUserRepository, and add an Role for it. IUserRepository userRepository; User user = userRepository.Get(Guid.NewGuid()); user.AddRole(new Role() { Name = "Administrator" }); In this case, i don't know how does the repository or unit of work can know that user has a new role? I think, a real persistence ignorance ORM framework should support POCO, and any changes occurs on the POCO itself, the persistence framework should know automatically. Even if change the object status through the method(AddRole, RemoveRole) like the above example. I know a lot of ORM can automatically persistent the changes if i use the Roles property, but sometimes i don't like this way because of the performance reason. Could anyone give me some ideas for this? Thanks. This is my first question on this site. I hope my English can be understood. Any answers will be very appreciated.

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• Testing for Adjacent Cells In a Multi-level Grid

  - by Steve

  I'm designing an algorithm to test whether cells on a grid are adjacent or not. The catch is that the cells are not on a flat grid. They are on a multi-level grid such as the one drawn below. Level 1 (Top Level) | - - - - - | | A | B | C | | - - - - - | | D | E | F | | - - - - - | | G | H | I | | - - - - - | Level 2 | -Block A- | -Block B- | | 1 | 2 | 3 | 1 | 2 | 3 | | - - - - - | - - - - - | | 4 | 5 | 6 | 4 | 5 | 6 | ... | - - - - - | - - - - - | | 7 | 8 | 9 | 7 | 8 | 9 | | - - - - - | - - - - - | | -Block D- | -Block E- | | 1 | 2 | 3 | 1 | 2 | 3 | | - - - - - | - - - - - | | 4 | 5 | 6 | 4 | 5 | 6 | ... | - - - - - | - - - - - | | 7 | 8 | 9 | 7 | 8 | 9 | | - - - - - | - - - - - | . . . . . . This diagram is simplified from my actual need but the concept is the same. There is a top level block with many cells within it (level 1). Each block is further subdivided into many more cells (level 2). Those cells are further subdivided into level 3, 4 and 5 for my project but let's just stick to two levels for this question. I'm receiving inputs for my function in the form of "A8, A9, B7, D3". That's a list of cell Ids where each cell Id has the format (level 1 id)(level 2 id). Let's start by comparing just 2 cells, A8 and A9. That's easy because they are in the same block. private static RelativePosition getRelativePositionInTheSameBlock(String v1, String v2) { RelativePosition relativePosition; if( v1-v2 == -1 ) { relativePosition = RelativePosition.LEFT_OF; } else if (v1-v2 == 1) { relativePosition = RelativePosition.RIGHT_OF; } else if (v1-v2 == -BLOCK_WIDTH) { relativePosition = RelativePosition.TOP_OF; } else if (v1-v2 == BLOCK_WIDTH) { relativePosition = RelativePosition.BOTTOM_OF; } else { relativePosition = RelativePosition.NOT_ADJACENT; } return relativePosition; } An A9 - B7 comparison could be done by checking if A is a multiple of BLOCK_WIDTH and whether B is (A-BLOCK_WIDTH+1). Either that or just check naively if the A/B pair is 3-1, 6-4 or 9-7 for better readability. For B7 - D3, they are not adjacent but D3 is adjacent to A9 so I can do a similar adjacency test as above. So getting away from the little details and focusing on the big picture. Is this really the best way to do it? Keeping in mind the following points: I actually have 5 levels not 2, so I could potentially get a list like "A8A1A, A8A1B, B1A2A, B1A2B". Adding a new cell to compare still requires me to compare all the other cells before it (seems like the best I could do for this step is O(n)) The cells aren't all 3x3 blocks, they're just that way for my example. They could be MxN blocks with different M and N for different levels. In my current implementation above, I have separate functions to check adjacency if the cells are in the same blocks, if they are in separate horizontally adjacent blocks or if they are in separate vertically adjacent blocks. That means I have to know the position of the two blocks at the current level before I call one of those functions for the layer below. Judging by the complexity of having to deal with mulitple functions for different edge cases at different levels and having 5 levels of nested if statements. I'm wondering if another design is more suitable. Perhaps a more recursive solution, use of other data structures, or perhaps map the entire multi-level grid to a single-level grid (my quick calculations gives me about 700,000+ atomic cell ids). Even if I go that route, mapping from multi-level to single level is a non-trivial task in itself.

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• Wine 1.6.2-Trying to switch to 32-bit Wineprefix from 64-bit Wine (Trusty 14.04). Can anyone help me out?

  - by AlternateSteve90

  Hello fellow Ubuntu users, I'm having a little trouble with Wine 1.6.1 and I was wondering if someone could help me out. I recently downloaded some 32-bit games that I'd wanted to try(BeamNG Drive and Bugbear's Next Car Game demo) and I had run into some trouble trying to get either of these games to run. So I came across a couple pieces of advice on the 'Net, one here on the Ubuntu community site and the other at BeamNG's forums, on how to create a 32-bit wineprefix on a 64-bit setup. I managed to be able to create the wine32 folder, but now I'm having trouble making it my default Wine setup. Anybody have any idea how I can do that? I'll post the URLs for said advice, btw: http://www.beamng.com/threads/1788-Installing-DRIVE-under-Linux-via-Wine How do I create a 32-bit WINE prefix? Here's what I've tried so far in the Terminal: steven@steven-HP-Pavilion-17-Notebook-PC:~$ WINEPREFIX='/home/user/wine32' WINEARCH='win32' wine 'wineboot' wine: chdir to /home/user/wine32 : No such file or directory steven@steven-HP-Pavilion-17-Notebook-PC:~$ WINEPREFIX='/home/steven/wine32' WINEARCH='win32' wine 'wineboot' wine: created the configuration directory '/home/steven/wine32' fixme:storage:create_storagefile Storage share mode not implemented. err:mscoree:LoadLibraryShim error reading registry key for installroot err:mscoree:LoadLibraryShim error reading registry key for installroot err:mscoree:LoadLibraryShim error reading registry key for installroot err:mscoree:LoadLibraryShim error reading registry key for installroot fixme:storage:create_storagefile Storage share mode not implemented. fixme:iphlpapi:NotifyAddrChange (Handle 0x10ee890, overlapped 0x10ee89c): stub wine: configuration in '/home/steven/wine32' has been updated. steven@steven-HP-Pavilion-17-Notebook-PC:~$ WINEPREFIX=$HOME/.wine32 wine dxsetup.exe wine: created the configuration directory '/home/steven/.wine32' fixme:storage:create_storagefile Storage share mode not implemented. err:mscoree:LoadLibraryShim error reading registry key for installroot err:mscoree:LoadLibraryShim error reading registry key for installroot err:mscoree:LoadLibraryShim error reading registry key for installroot err:mscoree:LoadLibraryShim error reading registry key for installroot fixme:storage:create_storagefile Storage share mode not implemented. fixme:iphlpapi:NotifyAddrChange (Handle 0x103e2b8, overlapped 0x103e2d0): stub fixme:storage:create_storagefile Storage share mode not implemented. fixme:iphlpapi:NotifyAddrChange (Handle 0x10fe890, overlapped 0x10fe89c): stub wine: configuration in '/home/steven/.wine32' has been updated. wine: cannot find L"C:\windows\system32\dxsetup.exe" steven@steven-HP-Pavilion-17-Notebook-PC:~$ WINEARCH=win64 winecfgsteven@steven-HP-Pavilion-17-Notebook-PC:~$ WINEPREFIX='/home/steven/wine32' WINEARCH='win32' wine 'wineboot' steven@steven-HP-Pavilion-17-Notebook-PC:~$ WINEARCH=win32 winecfg wine: WINEARCH set to win32 but '/home/steven/.wine' is a 64-bit installation. steven@steven-HP-Pavilion-17-Notebook-PC:~$ WINEPREFIX='/home/steven/wine32' WINEARCH='win32' wine 'wineboot' steven@steven-HP-Pavilion-17-Notebook-PC:~$ WINEPREFIX='/home/user/wine32' WINEARCH='win32' wine 'wineboot' wine: chdir to /home/user/wine32 : No such file or directory steven@steven-HP-Pavilion-17-Notebook-PC:~$ WINEPREFIX='/home/steven/wine32' WINEARCH='win32' wine 'wineboot' steven@steven-HP-Pavilion-17-Notebook-PC:~$ WINEPREFIX=/home/steven/wine32 WINEARCH='win32' wine 'wineboot' steven@steven-HP-Pavilion-17-Notebook-PC:~$ WINEPREFIX=/home/steven/wine32 WINEARCH=win32 wine wineboot steven@steven-HP-Pavilion-17-Notebook-PC:~$ So, yeah. TBH, though, I'm far from an expert and perhaps I've been going about it all the wrong way. In the meantime, I'll try to keep looking for solutions on my own, but if anybody can help me solve this dilemma, especially if anyone happens to own any of these two games in particular, I'd appreciate it. :)

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• &lsquo;Responsive Web Design with Macaw&rsquo;&ndash; free book updated

  - by ihaynes

  Originally posted on: http://geekswithblogs.net/ihaynes/archive/2014/08/12/lsquoresponsive-web-design-with-macawrsquondash-free-book-updated.aspxThe free book on Macaw by Schonne Eldridge that I mentioned before has been updated. If you’re already subscribed you’ll get alerts for updates. If not the book is well worth getting to start you off with Macaw. If you haven’t tried Macaw yet, heck, you’re missing something big. The book is available from http://schonne.com/macaw Macaw itself is at http://macaw.co

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• UEC - Can the Cluster Controller and Storage Controller be seperate systems?

  - by Jeremy Hajek

  My department is implementing an Ubuntu Enterprise Cloud. I have done the testing and am quite comfortable with the 4 pieces, CC/SC, CLC, WS, NC. Looking at various documents below it appears the the Storage Controller and Cluster Controller (eucalyptus-sc and eucalyptus-cc) are always installed on the same system. My question is this: can I install the storage controller and the cluster controller on separate systems? http://open.eucalyptus.com/wiki/EucalyptusAdvanced_v2.0 the picture indicates that cc and sc are two different machines http://www.canonical.com/sites/default/files/active/Whitepaper-UbuntuEnterpriseCloudArchitecture-v1.pdf P.10 1st paragraph uses the word "machine(s)" http://software.intel.com/file/31966 P. 8 indicates the same separate architecture BUT... https://help.ubuntu.com/community/UEC/PackageInstallSeparate indicates below that the SC and CC are to be on the same system.

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