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  • How granular should a command be in a CQ[R]S model?

    - by Aaronaught
    I'm considering a project to migrate part of our WCF-based SOA over to a service bus model (probably nServiceBus) and using some basic pub-sub to achieve Command-Query Separation. I'm not new to SOA, or even to service bus models, but I confess that until recently my concept of "separation" was limited to run-of-the-mill database mirroring and replication. Still, I'm attracted to the idea because it seems to provide all the benefits of an eventually-consistent system while sidestepping many of the obvious drawbacks (most notably the lack of proper transactional support). I've read a lot on the subject from Udi Dahan who is basically the guru on ESB architectures (at least in the Microsoft world), but one thing he says really puzzles me: As we get larger entities with more fields on them, we also get more actors working with those same entities, and the higher the likelihood that something will touch some attribute of them at any given time, increasing the number of concurrency conflicts. [...] A core element of CQRS is rethinking the design of the user interface to enable us to capture our users’ intent such that making a customer preferred is a different unit of work for the user than indicating that the customer has moved or that they’ve gotten married. Using an Excel-like UI for data changes doesn’t capture intent, as we saw above. -- Udi Dahan, Clarified CQRS From the perspective described in the quotation, it's hard to argue with that logic. But it seems to go against the grain with respect to SOAs. An SOA (and really services in general) are supposed to deal with coarse-grained messages so as to minimize network chatter - among many other benefits. I realize that network chatter is less of an issue when you've got highly-distributed systems with good message queuing and none of the baggage of RPC, but it doesn't seem wise to dismiss the issue entirely. Udi almost seems to be saying that every attribute change (i.e. field update) ought to be its own command, which is hard to imagine in the context of one user potentially updating hundreds or thousands of combined entities and attributes as it often is with a traditional web service. One batch update in SQL Server may take a fraction of a second given a good highly-parameterized query, table-valued parameter or bulk insert to a staging table; processing all of these updates one at a time is slow, slow, slow, and OLTP database hardware is the most expensive of all to scale up/out. Is there some way to reconcile these competing concerns? Am I thinking about it the wrong way? Does this problem have a well-known solution in the CQS/ESB world? If not, then how does one decide what the "right level" of granularity in a Command should be? Is there some "standard" one can use as a starting point - sort of like 3NF in databases - and only deviate when careful profiling suggests a potentially significant performance benefit? Or is this possibly one of those things that, despite several strong opinions being expressed by various experts, is really just a matter of opinion?

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  • Data Transformation Pipeline

    - by davenewza
    I have create some kind of data pipeline to transform coordinate data into more useful information. Here is the shell of pipeline: public class PositionPipeline { protected List<IPipelineComponent> components; public PositionPipeline() { components = new List<IPipelineComponent>(); } public PositionPipelineEntity Process(Position position) { foreach (var component in components) { position = component.Execute(position); } return position; } public PositionPipeline RegisterComponent(IPipelineComponent component) { components.Add(component); return this; } } Every IPipelineComponent accepts and returns the same type - a PositionPipelineEntity. Code: public interface IPipelineComponent { PositionPipelineEntity Execute(PositionPipelineEntity position); } The PositionPipelineEntity needs to have many properties, many which are unused in certain components and required in others. Some properties will also have become redundant at the end of the pipeline. For example, these components could be executed: TransformCoordinatesComponent: Parse the raw coordinate data into a Coordinate type. DetermineCountryComponent: Determine and stores country code. DetermineOnRoadComponent: Determine and store whether coordinate is on a road. Code: pipeline .RegisterComponent(new TransformCoordinatesComponent()) .RegisterComponent(new DetermineCountryComponent()) .RegisterComponent(new DetermineOnRoadComponent()); pipeline.Process(positionPipelineEntity); The PositionPipelineEntity type: public class PositionPipelineEntity { // Only relevant to the TransformCoordinatesComponent public decimal RawCoordinateLatitude { get; set; } // Only relevant to the TransformCoordinatesComponent public decimal RawCoordinateLongitude { get; set; } // Required by all components after TransformCoordinatesComponent public Coordinate CoordinateLatitude { get; set; } // Required by all components after TransformCoordinatesComponent public Coordinate CoordinateLongitude { get; set; } // Set in DetermineCountryComponent, not required anywhere. // Requires CoordinateLatitude and CoordinateLongitude (TransformCoordinatesComponent) public string CountryCode { get; set; } // Set in DetermineOnRoadComponent, not required anywhere. // Requires CoordinateLatitude and CoordinateLongitude (TransformCoordinatesComponent) public bool OnRoad { get; set; } } Problems: I'm very concerned about the dependency that a component has on properties. The way to solve this would be to create specific types for each component. The problem then is that I cannot chain them together like this. The other problem is the order of components in the pipeline matters. There is some dependency. The current structure does not provide any static or runtime checking for such a thing. Any feedback would be appreciated.

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  • Which pattern is best for large project

    - by shamim
    I have several years of software development experience, but I am not a keen and adroit programmer, to perform better I need helping hands. Recently I engaged in an ERP project. For this project want a very effective structure, which will be easily maintainable and have no compromise about performance issue. Below structures are now present in my old projects. Entity Layer BusinessLogic Layer. DataLogic Layer UI Layer. Bellow picture describe how they are internally connected. For my new project want to change my project structure, I want to follow below steps: Core Layer(common) BLL DAL Model UI Bellow picture describe how they are internally connected. Though goggling some initial type question’s are obscure to me, they are : For new project want to use Entity framework, is it a good idea? Will it increase my project performance? Will it more maintainable than previous structure? Entity Framework core disadvantages/benefits are? For my project need help to select best structure. Will my new structure be better than the old one?

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  • Moving all UI logic to Client Side?

    - by Mag20
    Our team originally consisted of mostly server side developers with minimum expertise in Javascript. In ASP.NET we used to write a lot of UI logic in code-behind or more recently through controllers in MVC. A little while ago 2 high level client side developers joined our team. They can do in HTMl/CSS/Javascript pretty much anything that we could previously do with server-side code and server-side web controls: Show/hide controls Do validation Control AJAX refreshing So I started to think that maybe it would be more efficient to just create a high level API around our business logic, kinda like Amazon Fulfillment API: http://docs.amazonwebservices.com/fws/latest/APIReference/, so that client side developers would fully take over the UI, while server side developers would only concentrate on business logic. So for ordering system you would have a high level API like: OrderService.asmx CreateOrderResponse CreateOrder(CreateOrderRequest) AddOrderItem AddPayment - SubmitPayment - GetOrderByID FindOrdersByCriteria ... There would be JSON/REST access to API, so it would be easy to consume from client-side UI. We could use this API for both internal UI development and also for 3-rd parties to create their own applications. With advances in Javascript and availability of good client side developers, is it a good time to get rid of code-behind/controllers and just concentrate on developing high level APIs (ala Amazon) that client side developers can consume?

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  • Oracle Exadata???????????????????

    - by takashi.hitomi
    2010?6????????????????????Oracle Exadata??????????????! ???????Oracle Exadata?????? ?????????2010 ???????????????????????????????????????????????????? ??????????????????????????????????????????????????????????????????????????????????? Oracle?Smart Grid????????Oracle Exadata??????????????????????????? ?21? ??·?????????? ????????????????? ????????????????????????????????????????????????????????????·?·????????????????????????????????????????????? ?????????????????????????????????????????????????????? ????????Oracle Exadata?????????????Oracle Database????????·?????????????? ?????????Update?Get?? Oracle Cloud Computing Summit ~ Database & Exadata Day ~ Oracle Cloud Computing Summit??????1? ????·??????????Oracle????????????????????????? ?????????·?????????????????????????????????·??????????????????????????????????????

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  • Disaster Recovery Example

    Previously, I use to work for a small internet company that sells dental plans online. Our primary focus concerning disaster prevention and recovery is on our corporate website and private intranet site. We had a multiphase disaster recovery plan that includes data redundancy, load balancing, and off-site monitoring. Data redundancy is a key aspect of our disaster recovery plan. The first phase of this is to replicate our data to multiple database servers and schedule daily backups of the databases that are stored off site. The next phase is the file replication of data amongst our web servers that are also backed up daily by our collocation. In addition to the files located on the server, files are also stored locally on development machines, and again backed up using version control software. Load balancing is another key aspect of our disaster recovery plan. Load balancing offers many benefits for our system, better performance, load distribution and increased availability. With our servers behind a load balancer our system has the ability to accept multiple requests simultaneously because the load is split between multiple servers. Plus if one server is slow or experiencing a failure the traffic is diverted amongst the other servers connected to the load balancer allowing the server to get back online. The final key to our disaster recovery plan is off-site monitoring that notifies all IT staff of any outages or errors on the main website encountered by the monitor. Messages are sent by email, voicemail, and SMS. According to Disasterrecovery.org, disaster recovery planning is the way companies successfully manage crises with minimal cost and effort and maximum speed compared to others that are forced to make decision out of desperation when disasters occur. In addition Sun Guard stated in 2009 that the first step in disaster recovery planning is to analyze company risks and factor in fixed costs for things like hardware, software, staffing and utilities, as well as indirect costs, such as floor space, power protection, physical and information security, and management. Also availability requirements need to be determined per application and system as well as the strategies for recovery.

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  • what tools and technologies an Technical Java Architect must hava [on hold]

    - by vicky
    I have more then eight years of experience in different Java tools, technologies and domains. Currently I am employed as a Technical Java Architect. I have worked on mobile, web, webservices, database, backend and desktop applications during this period. Everything was OK untill I got a few very good offers regarding an enterprise architect, solutions architect, java architects roles. But each one required different tool set. One was regarding experience in all Apache stack and technologies. So, help me which tools and technologies a real java technical Architect shuold have ? So that I can equip myself with that. Thanks.

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  • Should business services cross bounded contexts?

    - by Paul T Davies
    Firstly, I am following the convention that a bounded context is synonymous to a department, or possibly one department has 1 to many bounded contexts. We have a client consultancy department that has a Documentation Service. Documents are stored in the Document Store Service (which is where all documents in the company are stored - it is a utility service), and the Documentation Service stores information about that document (a business service). As it was designed for the client consultancy, it is information relevant to them. Now health and safety need somewhere to store information about a document. This is different information to client consultancy, but I have been instructed to extend the existing service to account for this extra information. I feel this service is now crossing a bounded context. My worry is that all departments will eventually store there information in here and the service will become bloated, trying to be all things to all departments. Each document record will only store a subset of the information because it will only belong to one department. It will get worse when different departments want to store the same information but refer to it in a diferent ways, or when two departments want to store different information that they refer to in the same way. In my understanding, this is exactly the reason for bounded contexts. I feel each department should have it's own business service for information about a document, but use the same utility service to actually store the document. What would be the correct approach?

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  • How should a JEE application store credentials for logging in to an external system?

    - by FGreg
    I am in a situation where I have a Web Application (WAR) that is accessing a REST service provided by another application. The REST service uses Basic HTTP Authentication. So that means the application calling the REST service needs to store user credentials somehow. To further complicate things, this is an enterprise, so there are different 'regions' the application moves through which will have different credentials for the same service (think local development, development region, integration region, user test region, production, etc...) My first instinct is that the credentials should be stored by the JEE container and the application should ask the container for the credentials (probably via JNDI?). I'm beginning to read about Java Authentication and Authorization Service (JAAS) but I'm not sure if that is the appropriate solution to this problem. How should a JEE application store credentials for logging in to an external system? A few more details about my WAR. It is a Spring-Integration project that has no front-end. The container I am working with is Websphere. I am using JEE 5 and Spring 4.0.1. To this point I have not needed to consider spring-security... does this situation mean I should re-evaluate that decision?

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  • Is it worth becoming a programmer?

    - by D. Higueras
    Hi everybody. I'm a first year student in CS and I absolutely love programming. Many people have told me it isn't so good once you start working. Some things like bringing your work home(thinking about how to solve problems), working many hours when the timeline reaches an end an so on. I've heard being a system administrator is a lot less stressing job, since you don't have to worry about it at home. So my questions are(for experienced programmers): Is it worth becoming a programmer? Does your job satisfy you enough to overcome these problems? Thanks in advance.

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  • Should I use a workflow engine?

    - by Fernando
    I need to add some new features to a PHP application. It is to follow the steps of a order. A process create some orders, the order goes to confirmation, then if approved is sent to a provider, later the provider confirm that can deliver the order, a request is made to the provider and so on... I need to register when every step is made and send notifications. Also, some steps have a estimate time, and if that time is elapsed I need to send notifications so everybody know about the delay. When a process starts, it have a predefined set of steps, but in a middle the user should be able to create new sub-steps, and delete or skip future steps.. Should I use a workflow engine? Which one do you suggests (free-opensource only)?

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  • admin-over-clients application

    - by azzido
    I have the same web application running on several different servers. Now I want a central place to administer everything in one web interface. What is the best way to do this? Should I provide a REST interface on every web application and let the admin application make all the calls? This seems like a common problem that's already been solved by smarter people than me. UPDATE: I want to change the application data per web application + see the results per web application

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  • What is the standard system architecture for MongoDB

    - by learner
    I know this question is too vague, so I would like to add some key numbers to give insights about what the scenario is Each Document size - 360KB Total Documents - 1.5 million Document created/day - 2k read intensive - YES Availability requirement - HIGH With these requirements in mind, here is what I believe should be the architecture, but not too sure, please share your experiences and point me to right directions 2 Linux Box(Ubuntu 11 would do)(on a different rack setup for availability) 64-bit Mongo Database 1-master(for read/wr1te) and 1-slave(read-only with replication ON) Sharding not needed at this point in time Thank you in advance

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  • Sun 280R architecture

    - by Andy
    How do I find out which architecture my Sun 280R is based on (eg . 501-6485 or 501-6690 etc) The command arch returns "sun4". Im running Solaris 10 Thanks

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  • Computer hobby and repairs

    - by John
    I have been a fulltime student recently working on graduate work to complete a graduate degree. While continuing my studies I have maintained my computer hobby. However, recently my computer hobby has been threatening to turn into a full-fledged side business. Because I am starting to have people come to me for computer help who I have never met before (who generally heard word-of-mouth from other people whose computers I looked at) I am seriously considering putting my conditions for working on a computer into writing (for potential damage control and perhaps liability reasons). Are there any standards for this that I should reference? Should responsibility be waived for times when the computer is left in my care or any time I look at a machine? Any advice you can provide here would be appreciated. What other lessons have you learned that I should be aware of in relation to helping people while continuing my studies as a hobby? Thank you in advance.

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  • foreign-architecture

    - by speedy-MACHO
    Always when I install something, I get the following error multiple times: Unknown configuration key 'foreign-architecture' found in your 'dpkg' configuration files. This warning will become a hard error at a later date, so please remove the offending configuration options and replace them with 'dpkg --add-architecture' invocations at the command line. When I try dpkg --add-architecture I get: Unknown configuration key `foreign-architecture' found in your `dpkg' configuration files. This warning will become a hard error at a later date, so please remove the offending configuration options and replace them with `dpkg --add-architecture' invocations at the command line. dpkg: error: --add-architecture takes one argument Type dpkg --help for help about installing and deinstalling packages [*]; Use `dselect' or `aptitude' for user-friendly package management; Type dpkg -Dhelp for a list of dpkg debug flag values; Type dpkg --force-help for a list of forcing options; Type dpkg-deb --help for help about manipulating *.deb files; Options marked [*] produce a lot of output - pipe it through `less' or `more' ! I've no problems yet, but since it says This warning will become a hard error at a later date I better do something about this. When I search 'foreign-architecture', I find an empty file, containing not a single byte. I somehow can't delete that file. Please help, it's a kind of creapy...

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  • What is the best way to diagrammatically represent a system threading architecture?

    - by thegreendroid
    I am yet to find the perfect way to diagrammatically represent the overall threading architecture for a system (using UML or otherwise). I am after a diagramming technique that would show all the threads in a given system and how they interact with each other. There are a few similar questions - Drawing Thread Interaction, UML Diagrams of Multithreaded Applications and Intuitive UML Approach to Depict Threads but they don't fully answer my question. What are some of the techniques that you've found useful to depict the overall threading architecture for a system?

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  • Are there any good Java/JVM libraries for my Expression Tree architecture?

    - by Snuggy
    My team and I are developing an enterprise-level application and I have devised an architecture for it that's best described as an "Expression Tree". The basic idea is that the leaf nodes of the tree are very simple expressions (perhaps simple values or strings). Nodes closer to the trunk will get more and more complex, taking the simpler nodes as their inputs and returning more complex results for their parents. Looking at it the other way, the application performs some task, and for this it creates a root expression. The root expression divides its input into smaller units and creates child expressions, which when evaluated it can use to build it's own result. The subdividing process continues until the simplest leaf nodes. There are two very important aspects of this architecture: It must be possible to manipulate nodes of the tree after it is built. The nodes may be given new input values to work with and any change in result for that node needs to be propagated back up the tree to the root node. The application must make best use of available processors and ultimately be scalable to other computers in a grid or in the cloud. Nodes in the tree will often be updating concurrently and notifying other interested nodes in the tree when they get a new value. Unfortunately, I'm not at liberty to discuss my actual application, but to aid understanding a little bit, you might imagine a kind of spreadsheet application being implemented with a similar architecture, where changes to cells in the table are propagated all over the place to other cells that need the result. The spreadsheet could get so massive that applying multi-core multi-computer distributed system to solve it would be of benefit. I've got my prototype "Expression Engine" working nicely on a single multi-core PC but I've started to run into a few concurrency issues (as expected because I haven't been taking too much care so far) so it's now time to start thinking about migrating the Engine to a more robust library, and that leads to a number of related questions: Is there any precedent for my "Expression Tree" architecture that I could research? What programming concepts should I consider. I realise this approach has many similarities to a functional programming style, and I'm already aware of the concepts of using futures and actors. Are there any others? Are there any languages or libraries that I should study? This question is inspired by my accidental discovery of Scala and the Akka library (which has good support for Actors, Futures, Distributed workloads etc.) and I'm wondering if there is anything else I should be looking at as well?

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  • change computer desktop icon in Windows 2008 R2 to display computer name

    - by Mouffette
    In Windows 2003 I was able to change the registry key as follows to display the actualy computer name on the desktop using the Computer Desktop Icon. System Key: [HKEY_CLASSES_ROOT\CLSID\{20D04FE0-3AEA-1069-A2D8-08002B30309D}] Change "LocalizedString" value to %COMPUTERNAME% I'm getting access denied messages using regedit for this key and I'm unable to give full rights to this specific key as well as administrator. Does anyone have a better solution for displaying the computer name on the desktop? Thanks.

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  • Wake up my company computer from a home computer

    - by Darcy
    I would like to learn if it is possible for me to send a packet (a magical one) from another computer to my computer. I am interested in waking up my computer at work from the one I am using at home. That is I would like to power it on at 7:00am by sending it a wake-on packet from the home computer. I have no idea how to carry out this seemingly trivial task, I hope someone could offer some basic ideas for me start. Thank you so much in advance.

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  • Sharp Architecture for Winform apps?

    - by CF_Maintainer
    The Sharp Architecture Contrib seems to suggest it is possible. It seemed like they had a dependency on "PostSharp" which has now been replaced with Castle interceptors. Has anyone used the Sharp Architecture for a non Web project? How was the experience? Does that mean one is locked in with castle as the IoC container when using Sharp architecture for non web purposes? If not Sharp Architecture, then what are some of the favored application frameworks for the non web world [spring.NET?] ? If one were to start a green field Winforms app, what application framework would be desirable?

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  • SAAS architecture and salesforce database architecture

    - by Farax
    Hello all, I am architecting a software project and I want to create a SAAS (Software As a service) one. I want to model my application along the lines of Salesforce. I really like there customization features but I am not sure how they really go about it. I read that they create an ID for every field that is required and then store the corresponding data too. Can anyone guide me as to how this is possible. For example, if I want to store an employee record. 2 fields (firstname, lastname) are already given and the user adds a third field(say DOB), how is data going to be stored? I would also appreciate if someone could give me some resources to practical examples of implementing a SAAS architecture. Thanks

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  • How to properly diagram lambda expressions or traversals through them in Architecture Explorer?

    - by MainMa
    I'm exploring a piece of code in Architecture Explorer in Visual Studio 2010 to study the relations between methods. I noticed a strange behavior. Take the following source code. It generates a hello message based on a template and a template engine, the template engine being a method (a sort of strategy pattern simplified at a maximum for demo purposes). public string GenerateHelloMessage(string personName) { return this.ApplyTemplate( this.DefaultTemplateEngine, this.GenerateLocalizedHelloTemplate(), personName); } private string GenerateLocalizedHelloTemplate() { return "Hello {0}!"; } public string ApplyTemplate( Func<string, string, string> templateEngine, string template, string personName) { return templateEngine(template, personName); } public string DefaultTemplateEngine(string template, string personName) { return string.Format(template, personName); } The graph generated from this code is this one: Change the first method from this: public string GenerateHelloMessage(string personName) { return this.ApplyTemplate( this.DefaultTemplateEngine, this.GenerateLocalizedHelloTemplate(), personName); } to this: public string GenerateHelloMessage(string personName) { return this.ApplyTemplate( (a, b) => this.DefaultTemplateEngine(a, b), this.GenerateLocalizedHelloTemplate(), personName); } and the graph becomes: While semantically identical, those two versions of code produce different dependency graphs, and Architecture Explorer shows no trace of the lambda expression (while Visual Studio's code coverage, for example, shows them, as well as Code analysis seems to be able to understand that the link exists). How would it be possible, without changing the source code, to: Either force Architecture Explorer to display everything, including lambda expressions, Or make it traverse lambda expressions while drawing a dependency through them (so in this case, drawing the dependency from GenerateHelloMessage to DefaultTemplateEngine in the second example)?

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