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• What is a good measure of strength of a link and influence of a node?

  - by Legend

  In the context of social networks, what is a good measure of strength of a link between two nodes? I am currently thinking that the following should give me what I want: For two nodes A and B: Strength(A,B) = (neighbors(A) intersection neighbors(B))/neighbors(A) where neighbors(X) gives the total number of nodes directly connected to X and the intersection operation above gives the number of nodes that are connected to both A and B. Of course, Strength(A,B) != Strength(B,A). Now knowing this, is there a good way to determine the influence of a node? I was initially using the Degree Centrality of a node to determine its "influence" but I somehow think its not a good idea because just because a node has a lot of outgoing links does not mean anything. Those links should be powerful as well. In that case, maybe using an aggregate of the strengths of each node connected to this node is a good idea to estimate its influence? I'm a little confused. Does anyone have any suggestions?

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• How to handle expired items?

  - by Mark

  My site allows users to post things on the site with an expiry date. Once the item has expired, it will no longer be displayed in the listings. Posts can also be closed, canceled, or completed. I think it would be be nicest just to be able to check for one attribute or status ("is active") rather than having to check for [is not expired, is not completed, is not closed, is not canceled]. Handling the rest of those is easy because I can just have one "status" field which is essentially an enum, but AFAIK, it's impossible to set the status to "expired" as soon as that time occurs. How do people typically handle this?

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• Would you store binary data in database or in file system?

  - by paul

  This is a question which has been asked before (large-text-and-images-in-sql) but mainly for data which will be changed. In my case the data will be stored and never changed. Just seems sensible to keep everything together. Are there any reasons why I should not store static binary data in a database? Assuming it is a sensible thing to do, are there any advantages to storing such data in separate tables? (You might begin to realise now that I'm not a DB expert...) Clarify: There will probably be no more than 10-20 users but these will be in the US and in the UK. The binary data will have to be transfered in any case.

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• Best Practice for CouchDB Document Versioning

  - by Groundwater

  Following my question here I am exmploring ideas for a generic approach to document versioning in CouchDB. While I imagine there may be no canonical approach, I had the following idea and am looking for feedback. I would like to maintain readable document ids as much as possible, so a document existing at /document1 would contain a pointer document to all existing versions on the system. The actual revision documents would be at something like /document1/308ef032a3801a where 308ef032a3801a is some random number or hash. Example The pointer document { "_id" : "document1", "versions" : [ "document1/308ef032a3801a" ] } The version document { "_id" : "document1/308ef032a3801a", ... actual content }

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• How to update SQL Server database from multiple data sources for ASP.Net MVC 4 application

  - by shaz

  I have 10+ SQL Server databases, from where I would use one table from each database to display information using the application that I am creating. For instance, DB1, DB2....DB10. NewDB (Account, Country, Costcenter....etc.). I have started with creating a new database which would contain all the information from all those 10+ databases. However, I am confused in many cases. First of all what process should I follow? Shall I create a table (in new database) with the same structure as the actual data source and insert data from actual data source to new database? Should I be doing this on the DBMS? If so, is it some scripting? (hint expected since very new to this) I am creating a report generation application which has 10+ data sources. I need some hint which way should I proceed? Thanks for advice/help in advance.

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• Java: refactoring static constants

  - by akf

  We are in the process of refactoring some code. There is a feature that we have developed in one project that we would like to now use in other projects. We are extracting the foundation of this feature and making it a full-fledged project which can then be imported by its current project and others. This effort has been relatively straight-forward but we have one headache. When the framework in question was originally developed, we chose to keep a variety of constant values defined as static fields in a single class. Over time this list of static members grew. The class is used in very many places in our code. In our current refactoring, we will be elevating some of the members of this class to our new framework, but leaving others in place. Our headache is in extracting the foundation members of this class to be used in our new project, and more specifically, how we should address those extracted members in our existing code. We know that we can have our existing Constants class subclass this new project's Constants class and it would inherit all of the parent's static members. This would allow us to effect the change without touching the code that uses these members to change the class name on the static reference. However, the tight coupling inherent in this choice doesn't feel right. before: public class ConstantsA { public static final String CONSTANT1 = "constant.1"; public static final String CONSTANT2 = "constant.2"; public static final String CONSTANT3 = "constant.3"; } after: public class ConstantsA extends ConstantsB { public static final String CONSTANT1 = "constant.1"; } public class ConstantsB { public static final String CONSTANT2 = "constant.2"; public static final String CONSTANT3 = "constant.3"; } In our existing code branch, all of the above would be accessible in this manner: ConstantsA.CONSTANT2 I would like to solicit arguments about whether this is 'acceptable' and/or what the best practices are.

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• Drawbacks of using an integer as a bitfield?

  - by Mark

  I have a bunch of boolean options for things like "accepted payment types" which can include things like cash, credit card, cheque, paypal, etc. Rather than having a half dozen booleans in my DB, I can just use an integer and assign each payment method an integer, like so PAYMENT_METHODS = ( (1<<0, 'Cash'), (1<<1, 'Credit Card'), (1<<2, 'Cheque'), (1<<3, 'Other'), ) and then query the specific bit in python to retrieve the flag. I know this means the database can't index by specific flags, but are there any other drawbacks?

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• Voting Script, Possibility of Simplifying Database Queries

  - by Sev

  I have a voting script which stores the post_id and the user_id in a table, to determine whether a particular user has already voted on a post and disallow them in the future. To do that, I am doing the following 3 queries. SELECT user_id, post_id from votes_table where postid=? AND user_id=? If that returns no rows, then: UPDATE post_table set votecount = votecount-1 where post_id = ? Then SELECT votecount from post where post_id=? To display the new votecount on the web page Any better way to do this? 3 queries are seriously slowing down the user's voting experience Edit In the votes table, vote_id is a primary key In the post table, post_id is a primary key. Any other suggestions to speed things up?

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• How do you manage web navigation info in your application?

  - by Dave

  I’m building an application where different users will have different menu items available to them depending on what they’ve paid for. There will also be multiple levels to the menu hierarchy. What’s the best approach to this problem? I’m assuming I need a database table that represents the menu hierarchy, including the parent-child relationships of the nodes in the navigation as well as the sorting of the items. Then another table which I use to manage whether a user is authorized to access a particular item in that table. When I render the view, I’d reference the menus, and the access rights of the user to output the menu, and I’d also need a function to check that same authorization from each controller in case a user manually types in a URL of a controller they’re not supposed to have access to. Is this the right approach? Any suggestions for caching this to prevent the constant look-ups of this type of info? I’m open to any suggestions on how you may have approached this type of requirement.

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• How I can Optimize this mySQL transaction within java code?

  - by worldpython

  Dear All, I am new to MySql database. I've large table(ID,...). I select ID frequently with java code and.And that make a heavy load on transaction select from tableName where ID=someID notes: 1.Database could be 100,000 records 2.I can't cache result 3.ID is a primary key 4.I try to optimize time needed to return result from query. Any ideas for optimization ? thanks in advance

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• Re-usable Obj-C classes with custom values: The right way

  - by Prairiedogg

  I'm trying to reuse a group of Obj-C clases between iPhone applications. The values that differ from app to app have been isolated and I'm trying to figure out the best way to apply these custom values to the classes on an app-to-app basis. Should I hold them in code? // I might have 10 customizable values for each class, that's a long signature! CarController *controller = [[CarController alloc] initWithFontName:@"Vroom" engine:@"Diesel" color:@"Red" number:11]; Should I store them in a big settings.plist? // Wasteful! I sometimes only use 2-3 of 50 settings! AllMyAppSettings *settings = [[AllMyAppSettings alloc] initFromDisk:@"settings.plist"]; MyCustomController *controller = [[MyCustomController alloc] initWithSettings:settings]; [settings release]; Should I have little, optional n_settings.plists for each class? // Sometimes I customize CarControllerSettings *carSettings = [[CarControllerSettings alloc] initFromDisk:@"car_settings.plist"]; CarController *controller = [[CarController alloc] initWithSettings:carSettings]; [carSettings release]; // Sometimes I don't, and CarController falls back to internally stored, reasonable defaults. CarController *controller = [[CarController alloc] initWithSettings:nil]; Or is there an OO solution that I'm not thinking of at all that would be better?

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• I am looking for some kind of code by Contracts that I can use with Eclipse

  - by devoured elysium

  I've tried before some Eclipse plugin (I don't remember its name) but it was lacking a lot of features (generics, for example). Is there anything easy to set up that would run on the last version of Java? Thanks

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• What programming shortcuts do you end up regretting or backing out?

  - by bryanjonker

  I saw this question and it reminded me of AutoGenerateColumns in the old DataGrid. The few times I've used them, I ended up backing it out because I needed data formatting past the standard "spit out the Data Source columns." Likewise, with toggle, it sounds like it would save time, but then you end up needing to keep track of state or something else, and you rewrite the code accordingly. Are there things that you end up using thinking it will save you time, but end up backing out because it doesn't do what you need?

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• Hide or Disable? In this example and in general...

  - by George

  I have the following set of controls. Scenario 1: If you select one of the first 3 radio buttons and click enter, focus will jump to the Passport Number text box. If the user selects "Other", the "Other, Please Specify" textbox is enabled and, for convenience, screen focus (the cursor is moved) to that textbox. Scenario 2: The "specify Other" text box is hidden until the user clicks on the Other Radio button. Upon doing so, the textbox is made visible and the cursor is placed in this textbox. Which scenario do you feel is a better approach? Perhaps you have another variation? Please state your reasoning. I would also appreciate it if you could make a generalized statement as to when hiding is better than disabling or vice versa, but I am also interested in this particular example. Thanks. Afetrthought: Perhaps, in the 2nd example, the "Please Specify" text would only appear after the user has selected the 'Other' radio button.

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• How do you determine how coarse or fine-grained a 'responsibility' should be when using the single r

  - by Mark Rogers

  In the SRP, a 'responsibility' is usually described as 'a reason to change', so that each class (or object?) should have only one reason someone should have to go in there and change it. But if you take this to the extreme fine-grain you could say that an object adding two numbers together is a responsibility and a possible reason to change. Therefore the object should contain no other logic, because it would produce another reason for change. I'm curious if there is anyone out there that has any strategies for 'scoping', the single-responsibility principle that's slightly less objective?

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• Objective-C Objects Having Each Other as Properties

  - by mwt

  Let's say we have two objects. Furthermore, let's assume that they really have no reason to exist without each other. So we aren't too worried about re-usability. Is there anything wrong with them "knowing about" each other? Meaning, can each one have the other as a property? Is it OK to do something like this in a mythical third class: Foo *f = [[Foo alloc] init]; self.foo = f; [f release]; Bar *b = [[Bar alloc] init]; self.bar = b; [b release]; foo.bar = bar; bar.foo = foo; ...so that they can then call methods on each other? Instead of doing this, I'm usually using messaging, etc., but sometimes this seems like it might be a tidier solution. I hardly ever see it in example code (maybe never), so I've shied away from doing it. Can somebody set me straight on this? Thanks.

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• How do you find the balance between Javascript (jQuery) and code behind in ASP.NET.

  - by PieterG

  Stackoverflow members, How do you currently find the balance between javascript and code behind. I have recently come across some extremely bad (in my eyes) legacy code that lends itself to chaos (someHugeJavafile.js) which contains a lot of the logic used in many of the pages. Let's say for example that you have a Form that you need to complete. 1. Personal Details 2. Address Information 3. Little bit more about yourself You don't want to overload the person with all the fields at once, so you decide to split it up into steps. Do you create separate pages for Personal Details, Address Information and a Little bit more about yourself. Do you create controls for each and hide and show them on a postback or using some update panel? Do you use jQuery and do some checking to ensure that the person has completed the required fields for the step and show the new "section" by using .show()? How do you usually find the balance?

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• Database date fields - Naming Convention

  - by Mark

  What's a good way of naming date/datetime fields? Can't decide if I want to use things like expiry_date, end_tme, created_on, or simply expires, modified.

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• How to cancel a deeply nested process

  - by Mystere Man

  I have a class that is a "manager" sort of class. One of it's functions is to signal that the long running process of the class should shut down. It does this by setting a boolean called "IsStopping" in class. public class Foo { bool isStoping void DoWork() { while (!isStopping) { // do work... } } } Now, DoWork() was a gigantic function, and I decided to refactor it out and as part of the process broke some of it into other classes. The problem is, Some of these classes also have long running functions that need to check if isStopping is true. public class Foo { bool isStoping void DoWork() { while (!isStopping) { MoreWork mw = new MoreWork() mw.DoMoreWork() // possibly long running // do work... } } } What are my options here? I have considered passing isStopping by reference, which I don't really like because it requires there to be an outside object. I would prefer to make the additional classes as stand alone and dependancy free as possible. I have also considered making isStopping a property, and then then having it call an event that the inner classes could be subscribed to, but this seems overly complex. Another option was to create a "Process Cancelation Token" class, similar to what .net 4 Tasks use, then that token be passed to those classes. How have you handled this situation? EDIT: Also consider that MoreWork might have a EvenMoreWork object that it instantiates and calls a potentially long running method on... and so on. I guess what i'm looking for is a way to be able to signal an arbitrary number of objects down a call tree to tell them to stop what they're doing and clean up and return.

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• Implementing a 'many-to-many' database

  - by Raven Dreamer

  Greetings, stack*overflow* In my database, I already have one table, 'contacts' that contains records of individual people. I also have several other tables in my database which represent "skill sets" that contain records denoting a particular skill. 1) Am I correct in plotting this as a "many-to-many" relationship? (each contact can have multiple skill sets, and each skill set can belong to multiple contacts) 2) I'm new to databases -- do I want to link the tables? 3) Is there a way to implement this in my program (C# + windows forms) such that for any given record in the 'contacts' table, either the names of all associated 'skill set' tables or all the 'skill' records associated with the 'contact' record could be retrieved? (Database is located on SQL Server Express 2008)

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• How to make technical training session useful and successful for trainee?

  - by metal-gear-solid

  Are these suggestions good to give for a successful training session? Practice time should be always given immediate after technical training? usually after receiving any technical session about any new thing we do routine work. If we don't do practice just after training, later when we do any work related to that training then we feel we need training again. So if we are getting training today and will not use it for some period of time (15 -30 -60 days) then the training is of no use, as it is at the wrong time. I.e. We will forget many things Any other suggestions which i should give? I'm trainee not trainer. What suggestion should i give to trainer/organizer?

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• Why doesn't Java Map extends Collection?

  - by polygenelubricants

  I was surprised by the fact that Map<?,?> is not a Collection<?>. I thought it'd make a LOT of sense if it was declared as such: public interface Map<K,V> extends Collection<Map.Entry<K,V>> After all, a Map<K,V> is a collection of Map.Entry<K,V>, isn't it? So is there a good reason why it's not implemented as such?

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• suggestions on syntax to express mathematical formula concisely

  - by aaa

  hello. I am developing functional domain specific embedded language within C++ to translate formulas into working code as concisely and accurately as possible. I post prototype in the comment, it is about 2 hundred lines long. Right now my language looks something like this (well, actually is going to look like): // implies two nested loops j=0:N, i=0,j (range(i) < j < N)[T(i,j) = (T(i,j) - T(j,i))/e(i+j)]; // implies summation over above expression sum(range(i) < j < N))[(T(i,j) - T(j,i))/e(i+j)]; I am looking for possible syntax improvements/extensions or just different ideas about expressing mathematical formulas as clearly and precisely as possible (in any language, not just C++). Can you give me some syntax examples relating to my question which can be accomplished in your language of choice which consider useful. In particular, if you have some ideas about how to translate the above code segments, I would be happy to hear them. Thank you just to clarify and give actual formula, my short-term goal is to express the following expression concisely where values in <> are already computed as 4-dimensional array

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• Does this copy the reference or the object?

  - by Water Cooler v2

  Sorry, I am being both thick and lazy, but mostly lazy. Actually, not even that. I am trying to save time so I can do more in less time as there's a lot to be done. Does this copy the reference or the actual object data? public class Foo { private NameValueCollection _nvc = null; public Foo( NameValueCollection nvc) { _nvc = nvc; } } public class Bar { public static void Main() { NameValueCollection toPass = new NameValueCollection(); new Foo( toPass ); // I believe this only copies the reference // so if I ever wanted to compare toPass and // Foo._nvc (assuming I got hold of the private // field using reflection), I would only have to // compare the references and wouldn't have to compare // each string (deep copy compare), right? } I think I know the answer for sure: it only copies the reference. But I am not even sure why I am asking this. I guess my only concern is, if, after instantiating Foo by calling its parameterized ctor with toPass, if I needed to make sure that the NVC I passed as toPass and the NVC private field _nvc had the exact same content, I would just need to compare their references, right?

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• Naming of boolean column in database table

  - by Space Cracker

  I have 'Service' table and the following column description as below Is User Verification Required for service ? Is User's Email Activation Required for the service ? Is User's Mobile Activation required for the service ? I Hesitate in naming these columns as below IsVerificationRequired IsEmailActivationRequired IsMobileActivationRequired or RequireVerification RequireEmailActivation RequireMobileActivation I can't determined which way is the best .So, Is one of the above suggested name is the best or is there other better ones ?

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