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  • Logging *Business* Events - use logging framework?

    - by UpTheCreek
    Hi, Something here doesn't feel right to me here, and so I would like the community's input - perhaps I am approaching this in the wrong way.... Q: Is is appropriate to use traditional infrastructure logging frameworks (like log4net) to log business events? When I say business events, I mean I want a global log like this: xx:xx Customer A purchased widget B. xx:xx Widget B was dispatched from warehouse. xx:xx Customer B payment declined. Most traditional infrastructure logging frameworks have event levels something like this: FATAL ERROR WARN INFO DEBUG An of course these messages don't fit well into that. Best description would be INFO, but of course these are important events, and INFO is of very low importance. I would still like this as a 'log' (e.g. I don't want to have to extract this from my business objects each time I want to see it) Seems to me I have two options: 1) Use a framework like log4net and just define a special logger for this (and live with the fact that it doesn't feel right). 2) Provide a service for performing this that doesn't rely on a traditional logging services. I'm leaning towards 2. What has anyone else done in a similar situations? Thanks!

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  • Code Contracts Vs. Object Initializers (.net 4.0)

    - by Mystagogue
    At face value, it would seem that object initializers present a problem for .net 4.0 "code contracts", where normally the invariant should be established by the time the object constructor is finished. Presumably, however, object-initializers require properties to be set after construction is complete. My question is if the invariants of "code contracts" are able to handle object initializers, "as if" the properties were set before the constructor completes? That would be very nice indeed!!

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  • How to leverage Spring Integration in a real-world JMS distributed architecture?

    - by ngeek
    For the following scenario I am looking for your advices and tips on best practices: In a distributed (mainly Java-based) system with: many (different) client applications (web-app, command-line tools, REST API) a central JMS message broker (currently in favor of using ActiveMQ) multiple stand-alone processing nodes (running on multiple remote machines, computing expensive operations of different types as specified by the JMS message payload) How would one best apply the JMS support provided by the Spring Integration framework to decouple the clients from the worker nodes? When reading through the reference documentation and some very first experiments it looks like the configuration of an JMS inbound adapter inherently require to use a subscriber, which in a decoupled scenario does not exist. Small side note: communication should happen via JMS text messages (using a JSON data structure for future extensibility).

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  • Singleton Pattern combine with a Decorator

    - by Mike
    Attached is a classic Decorator pattern. My question is how would you modify the below code so that you can wrap zero or one of each topping on to the Pizza Right now I can have a Pepporini - Sausage -- Pepporini -- Pizza class driving the total cost up to $10, charging twice for Pepporini. I don't think I want to use the Chain of Responsibility pattern as order does not matter and not all toppings are used? Thank you namespace PizzaDecorator { public interface IPizza { double CalculateCost(); } public class Pizza: IPizza { public Pizza() { } public double CalculateCost() { return 8.00; } } public abstract class Topping : IPizza { protected IPizza _pizzaItem; public Topping(IPizza pizzaItem) { this._pizzaItem = pizzaItem; } public abstract double CalculateCost(); } public class Pepporini : Topping { public Pepporini(IPizza pizzaItem) : base(pizzaItem) { } public override double CalculateCost() { return this._pizzaItem.CalculateCost() + 0.50; } } public class Sausage : Topping { public Sausage(IPizza pizzaItem) : base(pizzaItem) { } public override double CalculateCost() { return this._pizzaItem.CalculateCost() + 1.00; } } public class Onions : Topping { public Onions(IPizza pizzaItem) : base(pizzaItem) { } public override double CalculateCost() { return this._pizzaItem.CalculateCost() + .25; } } }

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  • How to show unread subforums?

    - by bilygates
    I have written a simple forum in PHP using PostgreSQL. The forum consists of a number of subforums (or categories, if you like) that contain topics. I have a table that stores when was the last time a user visited a topic. It's something like this: user_id, topic_id, timestamp. I can easily determine what topics should be marked as unread by comparing the timestamp of the last topic reply with the timestamp of the last user visit. My question is: how do I efficiently determine what subforums (categories) should be marked as unread? All I've come up with is this: every time a user visits a topic, update the visit timestamp and check if all the topics from the current subforum are read or unread. If they are all read, mark the subforum as read for the user. Else, mark it as unread. But I think there must be another way. Thank you in advance.

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  • coding in native language

    - by radi
    is it possible to someone to invent a new programming language in his native language , and if it possible how to do that and what the tools he need to write compiler for it . thanks .

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  • Understanding MongoDB (and NoSQL in general) and how to make the best use of it

    - by Earlz
    Hello, I am beginning to think that my next project I am wanting to do would work better with a NoSQL solution. The project would either involve a ton of 2-column tables or a ton of dynamic queries with dynamically generated columns in a traditional SQL database. So I feel a NoSQL database would be much cleaner. I'm looking at MongoDB and it looks pretty promising. Anyway, I'm attempting to make sense of it all. Also, I will be using MongoMapper in Ruby. Anyway though, I'm confused as to how to layout things in such a freeform database. I've read http://stackoverflow.com/questions/2170152/nosql-best-practices and the answer there says that normalization is usually bad in a NoSQL DB. So how would be the best way of laying out say a simple blog with users, posts, and comments? My natural thought was to have three collections for each and then link them by a unique ID. But this apparently is wrong? So, what are some of the ways to lay out such a thing? My concern with the answer given in the other question is, what if the author's name changed? You'd have to go through updating a ton of posts and comments. But is this an okay thing to do with NoSQL?

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  • Clean up upon the kill signal

    - by Begui
    How do you handle clean up when the program receives a kill signal? For instance, there is an application I connect to that wants any third party app (my app) to send a finish command. What is the best say to send that finish command when my app has been destroyed with a kill -9?

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  • How do I write this MySQL query?

    - by CT
    I am working on an Asset DB using a lamp stack. In this example consider the following 5 tables: asset, server, laptop, desktop, software All tables have a primary key of id, which is a unique asset id. Every object has all asset attributes and then depending on type of asset has additional attributes in the corresponding table. If the type is a server, desktop or laptop it also has items in the software table. Here are the table create statements: // connect to mysql server and database "asset_db" mysql_connect("localhost", "asset_db", "asset_db") or die(mysql_error()); mysql_select_db("asset_db") or die(mysql_error()); // create asset table mysql_query("CREATE TABLE asset( id VARCHAR(50) PRIMARY KEY, company VARCHAR(50), location VARCHAR(50), purchase_date VARCHAR(50), purchase_order VARCHAR(50), value VARCHAR(50), type VARCHAR(50), notes VARCHAR(200))") or die(mysql_error()); echo "Asset Table Created.</br />"; // create software table mysql_query("CREATE TABLE software( id VARCHAR(50) PRIMARY KEY, software VARCHAR(50), license VARCHAR(50))") or die(mysql_error()); echo "Software Table Created.</br />"; // create laptop table mysql_query("CREATE TABLE laptop( id VARCHAR(50) PRIMARY KEY, manufacturer VARCHAR(50), model VARCHAR(50), serial_number VARCHAR(50), esc VARCHAR(50), user VARCHAR(50), prev_user VARCHAR(50), warranty VARCHAR(50))") or die(mysql_error()); echo "Laptop Table Created.</br />"; // create desktop table mysql_query("CREATE TABLE desktop( id VARCHAR(50) PRIMARY KEY, manufacturer VARCHAR(50), model VARCHAR(50), serial_number VARCHAR(50), esc VARCHAR(50), user VARCHAR(50), prev_user VARCHAR(50), warranty VARCHAR(50))") or die(mysql_error()); echo "Desktop Table Created.</br />"; // create server table mysql_query("CREATE TABLE server( id VARCHAR(50) PRIMARY KEY, manufacturer VARCHAR(50), model VARCHAR(50), warranty VARCHAR(50))") or die(mysql_error()); echo "Server Table Created.</br />"; ?> How do I query the database so that if I search by id, I receive all related fields to that asset id? Thank you.

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  • Storing n-grams in database in < n number of tables.

    - by kurige
    If I was writing a piece of software that attempted to predict what word a user was going to type next using the two previous words the user had typed, I would create two tables. Like so: == 1-gram table == Token | NextWord | Frequency ------+----------+----------- "I" | "like" | 15 "I" | "hate" | 20 == 2-gram table == Token | NextWord | Frequency ---------+------------+----------- "I like" | "apples" | 8 "I like" | "tomatoes" | 12 "I hate" | "tomatoes" | 20 "I hate" | "apples" | 2 Following this example implimentation the user types "I" and the software, using the above database, predicts that the next word the user is going to type is "hate". If the user does type "hate" then the software will then predict that the next word the user is going to type is "tomatoes". However, this implimentation would require a table for each additional n-gram that I choose to take into account. If I decided that I wanted to take the 5 or 6 preceding words into account when predicting the next word, then I would need 5-6 tables, and an exponentially increase in space per n-gram. What would be the best way to represent this in only one or two tables, that has no upper-limit on the number of n-grams I can support?

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  • Modular enterprise architecture using MVC and Orchard CMS

    - by MrJD
    I'm making a large scale MVC application using Orchard. And I'm going to be separating my logic into modules. I'm also trying to heavily decouple the application for maximum extensibility and testability. I have a rudimentary understanding of IoC, Repository Pattern, Unit of Work pattern and Service Layer pattern. I've made myself a diagram. I'm wondering if it is correct and if there is anything I have missed regarding an extensible application. Note that each module is a separate project.

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  • Good tool to visualise database schema?

    - by Mat
    Are there any good tools for visualising a pre-existing database schema? I'm using MySQL if it matters. I'm currently using MySQL Workbench to process an SQL create script dump, but it's clunky, slow and a manual process to drag all the tables about (which would be okay if it wasn't so slow).

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  • how can i use switch statement on type-safe enum pattern

    - by Fer
    I found a goodlooking example about implementation enums in a different way. That is called type-safe enum pattern i think. I started using it but i realized that i can not use it in a switch statement. My implementation looks like the following: public sealed class MyState { private readonly string m_Name; private readonly int m_Value; public static readonly MyState PASSED= new MyState(1, "OK"); public static readonly MyState FAILED= new MyState(2, "ERROR"); private MyState(int value, string name) { m_Name = name; m_Value = value; } public override string ToString() { return m_Name; } public int GetIntValue() { return m_Value; } } What can i add to my class in order to be able to use this pattern in switch statements in C#? Thanks.

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  • Problem implementing Interceptor pattern

    - by ph0enix
    I'm attempting to develop an Interceptor framework (in C#) where I can simply implement some interfaces, and through the use of some static initialization, register all my Interceptors with a common Dispatcher to be invoked at a later time. The problem lies in the fact that my Interceptor implementations are never actually referenced by my application so the static constructors never get called, and as a result, the Interceptors are never registered. If possible, I would like to keep all references to my Interceptor libraries out of my application, as this is my way of (hopefully) enforcing loose coupling across different modules. Hopefully this makes some sense. Let me know if there's anything I can clarify... Does anyone have any ideas, or perhaps a better way to go about implementing my Interceptor pattern? Update: I came across Spring.NET. I've heard of it before, but never really looked into it. It sounds like it has a lot of great features that would be very useful for what I'm trying to do. Does anyone have any experience with Spring.NET? TIA, Jeremy

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  • How do I recover from an unchecked exception?

    - by erickson
    Unchecked exceptions are alright if you want to handle every failure the same way, for example by logging it and skipping to the next request, displaying a message to the user and handling the next event, etc. If this is my use case, all I have to do is catch some general exception type at a high level in my system, and handle everything the same way. But I want to recover from specific problems, and I'm not sure the best way to approach it with unchecked exceptions. Here is a concrete example. Suppose I have a web application, built using Struts2 and Hibernate. If an exception bubbles up to my "action", I log it, and display a pretty apology to the user. But one of the functions of my web application is creating new user accounts, that require a unique user name. If a user picks a name that already exists, Hibernate throws an org.hibernate.exception.ConstraintViolationException (an unchecked exception) down in the guts of my system. I'd really like to recover from this particular problem by asking the user to choose another user name, rather than giving them the same "we logged your problem but for now you're hosed" message. Here are a few points to consider: There a lot of people creating accounts simultaneously. I don't want to lock the whole user table between a "SELECT" to see if the name exists and an "INSERT" if it doesn't. In the case of relational databases, there might be some tricks to work around this, but what I'm really interested in is the general case where pre-checking for an exception won't work because of a fundamental race condition. Same thing could apply to looking for a file on the file system, etc. Given my CTO's propensity for drive-by management induced by reading technology columns in "Inc.", I need a layer of indirection around the persistence mechanism so that I can throw out Hibernate and use Kodo, or whatever, without changing anything except the lowest layer of persistence code. As a matter of fact, there are several such layers of abstraction in my system. How can I prevent them from leaking in spite of unchecked exceptions? One of the declaimed weaknesses of checked exceptions is having to "handle" them in every call on the stack—either by declaring that a calling method throws them, or by catching them and handling them. Handling them often means wrapping them in another checked exception of a type appropriate to the level of abstraction. So, for example, in checked-exception land, a file-system–based implementation of my UserRegistry might catch IOException, while a database implementation would catch SQLException, but both would throw a UserNotFoundException that hides the underlying implementation. How do I take advantage of unchecked exceptions, sparing myself of the burden of this wrapping at each layer, without leaking implementation details?

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  • How to decide which colors to use that look most similar across most screens/monitors?

    - by Lyon
    Hi, I'm baffled. I'm trying to find suitable colors for a logo that would look similar across most monitors/screens. I know it's near impossible, but how does one end up with the color palette that new Google logo and Facebook "blue" uses for example? I've a monitor that has been calibrated, and a few laptop screens that have default settings. Yet both the Google logo and facebook's look similar (although they aren't using colors restricted to the web safe 216 palette. Any ideas? thoughts? Thanks

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  • How to track history of db tables that include many-to-many mapping tables?

    - by chacmool
    I have seen several questions here on tracking db history, but can't seem to find one that matches our situation. We need to track the history of several tables, some of which are many-to-many linking tables. Eg say we have this schema: EntityA id name EntityB id name ABLink A_id B_id So, tracking changes to EntityA or EntityB seems pretty straightforward. We can keep a log table with the same columns plus a date stamp and user. But what about the links? How do we maintain the set of links that are valid for a given version of the data? We need to be able to recreate a history of the data showing changes in chronological order. So if a link added or deleted, we indicate that. Etc.

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  • Statement hierarchy in programming languages

    - by sudo
    I quickly wrote an interpreter for some sort of experimental programing language i came up with, in PHP (yes, in PHP). The language itself doesn't have anything really special, I just wanted to give it a try. I got the basic things working (Hello World, input to output, string manipulation, arithmetics) but I'm getting stuck with the management of blocks and grouped statements. What I mean is: PHP and most other languages let you do this: ((2+2)*(8+2)+2), of course not only with mathematical computations. My program structure currently consists of a multidimensional array built like this: ID => Type (Identifier, String, Int, Newline, EOF, Comma, ...) Contents (If identifier, int or string) How could I allow statements to be executed in a defined order like in the PHP example above?

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  • Is there an ORM that supports composition w/o Joins

    - by Ken Downs
    EDIT: Changed title from "inheritance" to "composition". Left body of question unchanged. I'm curious if there is an ORM tool that supports inheritance w/o creating separate tables that have to be joined. Simple example. Assume a table of customers, with a Bill-to address, and a table of vendors, with a remit-to address. Keep it simple and assume one address each, not a child table of addresses for each. These addresses will have a handful of values in common: address 1, address 2, city, state/province, postal code. So let's say I'd have a class "addressBlock" and I want the customers and vendors to inherit from this class, and possibly from other classes. But I do not want separate tables that have to be joined, I want the columns in the customer and vendor tables respectively. Is there an ORM that supports this? The closest question I have found on StackOverflow that might be the same question is linked below, but I can't quite figure if the OP is asking what I am asking. He seems to be asking about foregoing inheritance precisely because there will be multiple tables. I'm looking for the case where you can use inheritance w/o generating the multiple tables. Model inheritance approach with Django's ORM

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  • Is extending a singleton class wrong?

    - by Anwar Shaikh
    I am creating a logger for an application. I am using a third party logger library. In which logger is implemented as singleton. I extended that logger class because I want to add some more static functions. In these static functions I internally use the instance (which is single) of Logger(which i inherited). I neither creates instance of MyLogger nor re-implemented the getInstance() method of super class. But I am still getting warnings like destructor of MyLogger can not be created as parent class (Loggger) destructor is not accessible. I want to know, I am I doing something wrong? Inheriting the singleton is wrong or should be avoided??

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  • Howto write a class where a property can be accessed without naming it.

    - by SchlaWiener
    I have a (dump) question regarding VB/C# I often use third party classes where I can access a child object with only specifying the id or key. Example: Instead of writing: DataRow row = GetAPopulatedDataRowSomeWhere(); Object result = row.Items[1]; // DataRow has no Items property Object result = row.Items["colName"]; // Also not possible I use this code to access the members: DataRow row = GetAPopulatedDataRowSomeWhere(); Object result = row[1]; Object result = row["colName"]; Can someone tell me how a class has to look like to support this syntax? My own class has a Dictionary that I want to access this way. MyClass["key"]; // <- that's what I want MyClass.SubItems["key"]; // <- that's how I use it now

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  • How to store data in mysql, to get the fastest performance?

    - by Oden
    Hey, I'm thinking about it, witch of the following two query types would give me the fastest performance for a user messaging module inside my site: The first one i thought about is a multi table setup, witch has a connection table, and a main table. The connection table holds the connection between accounts, and the messaging table. In this case a query would look like following, to get some data of the author, and the messages he has sent: SELECT m.*, a.username FROM messages AS m LEFT JOIN connection_table ON (message_id = m.id) LEFT JOIN accounts AS a ON (account_id = a.id) WHERE m.id = '32341' Inserting into it is a little bit more "complicated". My other idea, and in my thought the better solution of this problem is that i store the data i would use in a connection table in the same table where is store the data of the mail. Sounds like i would get lots of duplicated entries, but no, because i have a field witch has text type and holds user ids like this: *24*32*249* If I want to query them, i use the mysql LIKE method. Deleting is an other problem, but for this i have one more field where i store who has deleted the post. Sad about that i don't know how to join this. So what would you recommend? Are there other ways?

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  • Generalized plugable caching pattern?

    - by BCS
    Given that it's one of the hard things in computer science, does anyone know of a way to set up a plugable caching strategy? What I'm thinking of would allow me to write a program with minimal thought as to what needs to be cached (e.i. use some sort of boiler-plate, low/no cost pattern that compiles away to nothing anywhere I might want caching) and then when things are further along and I know where I need caching I can add it in without making invasive code changes. As an idea to the kind of solution I'm looking for; I'm working with the D programing language (but halfway sane C++ would be fine) and I like template.

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