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• Technology Plan - Which tools should I use?

  - by Armadillo

  Hi, Soon, I'll start my own software company. My primary product/solution will be a Billing/Invoice Software. In a near future, I pretend to expand this first module to an ERP. My app should be able to run as a stand-alone application and as a Web-based application (so there will be, probably two GUI for the same Database). My problem, now, is to choose the right tools; I'm talking about what programming language(s) should I use, what kind of database should I choose, and stuff like that. I'm primarily a VB6 programmer, so probably I'll choose the .net framework (vb/c#). But I'm seriously thinking about Java. Java has 2 "pros" that I really like: write once, run anywhere and it is free (I think...). I've been thinking about RIAs too, but I just don't have any substantial feedback about them... Then, I'll need a report tool. Crystal Reports? HTML based Reports? Other? Databases: I'm not sure if I should use SQL-Server Express or PostgreSQL (or other). I'd be happy to hear any comments and advices Thanks

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• From where to send mails in a MVC framework, so that there is no duplication of code?

  - by Sabya

  It's a MVC question. Here is the situation: I am writing an application where I have "groups". You can invite other persons to your groups by typing their email and clicking "invite". There are two ways this functionality can be called: a) web interface and b) API After the mail sending is over I want to report to the user which mails were sent successfully (i.e., if the SMTP send succeeded. Currently, I am not interested in reporting mail bounces). So, I am thinking how should I design so that there is no code duplication. That is, API and web-interface should share the bulk of the code. To do this, I can create the method "invite" inside the model "group". So, the API and and the Web-interface can just call: group-invite($emailList); This method can send the emails. But the, problem is, then I have to access the mail templates, create the views for the mails, and then send the mails. Which should actually be in the "View" part or at least in the "Controller" part. What is the most elegant design in this situation? Note: I am really thinking to write this in the Model. My only doubt is: previously I thought sending mails also as "presentation". Since it is may be considered as a different form of generating output.

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• pure/const functions in C++

  - by Albert

  Hi, I'm thinking of using pure/const functions more heavily in my C++ code. (pure/const attribute in GCC) However, I am curious how strict I should be about it and what could possibly break. The most obvious case are debug outputs (in whatever form, could be on cout, in some file or in some custom debug class). I probably will have a lot of functions, which don't have any side effects despite this sort of debug output. No matter if the debug output is made or not, this will absolutely have no effect on the rest of my application. Or another case I'm thinking of is the use of my own SmartPointer class. In debug mode, my SmartPointer class has some global register where it does some extra checks. If I use such an object in a pure/const function, it does have some slight side effects (in the sense that some memory probably will be different) which should not have any real side effects though (in the sense that the behaviour is in any way different). Similar also for mutexes and other stuff. I can think of many complex cases where it has some side effects (in the sense of that some memory will be different, maybe even some threads are created, some filesystem manipulation is made, etc) but has no computational difference (all those side effects could very well be left out and I would even prefer that). How does it work out in practice? If I mark such functions as pure/const, could it break anything (considering that the code is all correct)?

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• GitHub solution for personal repo

  - by Luke Maurer

  So I've got my private SVN repo on my home server, and it has maybe 30 different modules thrown together in it, ranging from abortive throw-away larks to a few endeavors that might actually go somewhere someday. But a recent filesystem failure (BTW, never ever EVER use XFS without a battery-backed hardware RAID) has me spooked and thinking of using a DVCS for all that. I've also just had quite the swig of the Git koolaid, and I've been working with GitHub of late, so that's where I'm looking right now. Of course, it would be silly to shell out major cash for a separate private Git repo for every little project, and I don't want to have to be selective about what I throw up there (I love all my children :-D ), so I'll have to be somewhat creative about this. I can happily use SSH to my home box to use Git the way I've been using SVN, and I'm thinking from there I could amalgamate everything into, say, a big project with 30 submodules, which I then push to GitHub. What'd be a sane way to set this up? Does using submodules sound feasible? How do I sync it all to my private GitHub repo? Cron job? Git hook? I'd love to hear it if anyone's done something similar. I'm not really married to Git or GitHub, so a sufficiently compelling feature of another solution might sway me. But if your answer does involve a different system (especially a different VCS), be advised it'll be a tougher sell :-)

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• Loading an FLV in Facebox with jQuery for IE7 and IE8

  - by Trip

  It goes almost without saying, this works perfectly in Chrome, Firefox, and Safari. IE (any version) being the problem. Objective: I am trying to load JWplayer which loads an FLV from S3 in a Facebox popup. jQuery(document).ready(function($) { $('a[rel*=facebox]').facebox() }) HTML (haml): %li#videoGirl = link_to 'What is HQchannel?', '#player', :rel => 'facebox' .grid_8.omega.alpha#player{:style => 'display: none;'} :javascript var so = new SWFObject('/flash/playerTrans.swf','mpl','640px','360px','0'); so.addParam('allowscriptaccess','always'); so.addParam('allowfullscreen','true'); so.addParam('wmode','transparent'); so.addVariable('file', 'http://hometownquarterlyvideos.s3.amazonaws.com/whatishqchannel.flv&autostart=true&controlbar=none&repeat=always&image=/flash/video_girl/whatishqchannel.jpg&icons=false&screencolor=none&backcolor=FFFFFF&screenalpha=0&overstretch'); so.addVariable('overstretch', 'true') so.write('player'); Problem: Despite the video being set to display: none;. It begins playing anyway. When clicking on the activation div, IE7 pops up a wrong sized blank div with a nav (params are set to not show nav and scrubber), and no buttons on the nav and srubber work. IE8 shows the right size but same behavior with nav and scrubber not working, and blank screen. My guess: I'm thinking that the problem is with the javascript not being called at the right times. It seems it's loading the facebox without the jwplayer. At least I assume. Hence the reason why the nav is there. I thinking that it did not read the javascript for that.

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• How to overcome the programmer's block ?

  - by Nicolas Dorier

  How do you do when, during the development of your application, you can't decide yourself what to do next. You have no problem technically speaking, you have no problem to write clean code BUT you have a problem to decide yourself on what to code now. And you spend time thinking and thinking again on your design, in the car, in the shower, and you cannot write a single line of code... I think we call this "analysis paralysis". I hate being in this state ! How can you avoid this ? How do you do to not fall in this state ? I think this occurs when we are writting a big chunk of code with no visible improvement, but I'm not sure... UPDATE Like some of you said, this problem is also what we call the "programmer's block" (analogy with the writer's block). Doing some TDD doesn't help because I'm stuck, I can't decide myself what class to code, what methods to put inside (even a name of method). Though I admit that it helps to break a big chunk of code into smaller ones. Like Talesh said my head becomes full of "what-if".

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• Dynamic Collapsable Flow Chart Online

  - by Simon

  Been looking through a number of other related posts relating to flowchart software. I have been asked to put together a document outlining some of the typical problems our users encounter with our software product. What I would like to do, is create an interactive/online flowchart that lets users choose from 4-5 overall headings on whats wrong. Then for this to dynamically expand more choices on pinpointing the problem, and so on and so on, until they can get a resolution to their problem. The key thing that I have not been able to find in some of the flowchart software out there, is having the click + expand element. - I dont want all options to appear to the end-user in a huge flow chart as it will distract away from their specific issue. - I want them to be able to click away and go down a specific avenue that will end up giving them some good things to try, based on their decisions/clicks. I was originally thinking of perhaps putting something in Flex or Silverlight (ideally someone would have a template out there) but am now thinking of taking advantage of 3rd party (ideally free) software. This will need to be hosted in a browser. Any ideas?

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• Moving UIScrollView in App

  - by jsetting32

  Currently, I am attempting to create the same effect as Yahoo! Weather's App where the vital day information is at the bottom of the page on the top of a UIScrollView, that's contained by a UIView. I am having a hard time thinking about how this is going to happen or how I should implement this. If the user taps on the top of the UIScrollView which is located near the bottom of the laoded UIView, and starts to scroll up (/), the UIScrollView's frame should be moved to the TOP of the current UIView's frame. So the UIScrollView's y-value should change to UIView's (self.view.frame.origin.y) if the user starts scrolling UP on the UIScrollView which is located on the UIView's y-pixel ~280. Here's what the UIViewController should look like in the beginning of loading the ViewController... Then once the user slides his finger from the bottom to the top of the screen... this should happen........ And when the user scrolls to the top of the UIScrollView with all the content within it... the view should go back to the start picture shown... How is this done? I was thinking several UIGestureRecognizer's and Instantiating the UIscrollview at the lower part of the UIView... _weatherView = [[UIScrollView alloc] initWithFrame:CGRectMake(self.view.frame.origin.x, self.view.frame.origin.y + 250, self.view.bounds.size.width, self.view.bounds.size.height - 44)]; _weatherView.contentSize = CGSizeMake(self.view.bounds.size.width, self.view.bounds.size.height * 4); _weatherView.backgroundColor = [UIColor clearColor]; [self.view addSubview:_weatherView]; The adding some UIGestureRecognizer delegate method.... But anyone have any ideas on the UIGestureRecognizer delegate method? And how it should be implemented? I can write the psuedo-code but I am having problems finding the delegate methods :P Thank you!!! ---- Break Time.... :)

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• MySQL "OR MATCH" hangs (very slow) on multiple tables

  - by Kerry

  After learning how to do MySQL Full-Text search, the recommended solution for multiple tables was OR MATCH and then do the other database call. You can see that in my query below. When I do this, it just gets stuck in a "busy" state, and I can't access the MySQL database. SELECT a.`product_id`, a.`name`, a.`slug`, a.`description`, b.`list_price`, b.`price`, c.`image`, c.`swatch`, e.`name` AS industry, MATCH( a.`name`, a.`sku`, a.`description` ) AGAINST ( '%s' IN BOOLEAN MODE ) AS relevance FROM `products` AS a LEFT JOIN `website_products` AS b ON (a.`product_id` = b.`product_id`) LEFT JOIN ( SELECT `product_id`, `image`, `swatch` FROM `product_images` WHERE `sequence` = 0) AS c ON (a.`product_id` = c.`product_id`) LEFT JOIN `brands` AS d ON (a.`brand_id` = d.`brand_id`) INNER JOIN `industries` AS e ON (a.`industry_id` = e.`industry_id`) WHERE b.`website_id` = %d AND b.`status` = %d AND b.`active` = %d AND MATCH( a.`name`, a.`sku`, a.`description` ) AGAINST ( '%s' IN BOOLEAN MODE ) OR MATCH ( d.`name` ) AGAINST ( '%s' IN BOOLEAN MODE ) GROUP BY a.`product_id` ORDER BY relevance DESC LIMIT 0, 9 Any help would be greatly appreciated. EDIT All the tables involved are MyISAM, utf8_general_ci. Here's the EXPLAIN SELECT statement: id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY a ALL NULL NULL NULL NULL 16076 Using temporary; Using filesort 1 PRIMARY b ref product_id product_id 4 database.a.product_id 2 1 PRIMARY e eq_ref PRIMARY PRIMARY 4 database.a.industry_id 1 1 PRIMARY <derived2> ALL NULL NULL NULL NULL 23261 1 PRIMARY d eq_ref PRIMARY PRIMARY 4 database.a.brand_id 1 Using where 2 DERIVED product_images ALL NULL NULL NULL NULL 25933 Using where I don't know how to make that look neater -- sorry about that UPDATE it returns the query after 196 seconds (I think correctly). The query without multiple tables takes about .56 seconds (which I know is really slow, we plan on changing to solr or sphinx soon), but 196 seconds?? If we could add a number to the relevance if it was in the brand name ( d.name ), that would also work

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• how does one _model_ data from relational databases in clojure ?

  - by sandeep

  I have asked this question on twitter as well the #clojure IRC channel, yet got no responses. There have been several articles about Clojure-for-Ruby-programmers, Clojure-for-lisp-programmers.. but what is the missing part is Clojure for ActiveRecord programmers . There have been articles about interacting with MongoDB, Redis, etc. - but these are key value stores at the end of the day. However, coming from a Rails background, we are used to thinking about databases in terms of inheritance - has_many, polymorphic, belongs_to, etc. The few articles about Clojure/Compojure + MySQL (ffclassic) - delve right into sql. Of course, it might be that an ORM induces impedence mismatch, but the fact remains that after thinking like ActiveRecord, it is very difficult to think any other way. I believe that relational DBs, lend themselves very well to the object-oriented paradigm because of them being , essentially, Sets. Stuff like activerecord is very well suited for modelling this data. For e.g. a blog - simply put class Post < ActiveRecord::Base has_many :comments end class Comment < ActiveRecord::Base belongs_to :post end How does one model this in Clojure - which is so strictly anti-OO ? Perhaps the question would have been better if it referred to all functional programming languages, but I am more interested from a Clojure standpoint (and Clojure examples)

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• Harvesting Dynamic HTTP Content to produce Replicating HTTP Static Content

  - by Neil Pitman

  I have a slowly evolving dynamic website served from J2EE. The response time and load capacity of the server are inadequate for client needs. Moreover, ad hoc requests can unexpectedly affect other services running on the same application server/database. I know the reasons and can't address them in the short term. I understand HTTP caching hints (expiry, etags....) and for the purpose of this question, please assume that I have maxed out the opportunities to reduce load. I am thinking of doing a brute force traversal of all URLs in the system to prime a cache and then copying the cache contents to geodispersed cache servers near the clients. I'm thinking of Squid or Apache HTTPD mod_disk_cache. I want to prime one copy and (manually) replicate the cache contents. I don't need a federation or intelligence amongst the slaves. When the data changes, invalidating the cache, I will refresh my master cache and update the slave versions, probably once a night. Has anyone done this? Is it a good idea? Are there other technologies that I should investigate? I can program this, but I would prefer a configuration of open source technologies solution Thanks

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• How does mercurial's bisect work when the range includes branching?

  - by Joshua Goldberg

  If the bisect range includes multiple branches, how does hg bisect's search work. Does it effectively bisect each sub-branch (I would think that would be inefficient)? For instance, borrowing, with gratitude, a diagram from an answer to this related question, what if the bisect got to changeset 7 on the "good" right-side branch first. @ 12:8ae1fff407c8:bad6 | o 11:27edd4ba0a78:bad5 | o 10:312ba3d6eb29:bad4 |\ | o 9:68ae20ea0c02:good33 | | | o 8:916e977fa594:good32 | | | o 7:b9d00094223f:good31 | | o | 6:a7cab1800465:bad3 | | o | 5:a84e45045a29:bad2 | | o | 4:d0a381a67072:bad1 | | o | 3:54349a6276cc:good4 |/ o 2:4588e394e325:good3 | o 1:de79725cb39a:good2 | o 0:2641cc78ce7a:good1 Will it then look only between 7 and 12, missing the real first-bad that we care about? (thus using "dumb" numerical order) or is it smart enough to use the full topography and to know that the first bad could be below 7 on the right-side branch, or could still be anywhere on the left-side branch. The purpose of my question is both (a) just to understand the algorithm better, and (b) to understand whether I can liberally extend my initial bisect range without thinking hard about what branch I go to. I've been in high-branching bisect situations where it kept asking me after every test to extend beyond the next merge, so that the whole procedure was essentially O(n). I'm wondering if I can just throw the first "good" marker way back past some nest of merges without thinking about it much, and whether that would save time and give correct results.

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• Calculate the year for ending month/day?

  - by Dave Jarvis

  Given: Start Year Start Month & Start Day End Month & End Day What SQL statement results in TRUE if a date lands between the Start and End days? 1st example: Start Date = 11-22 End Date = 01-17 Start Year = 2009 Specific Date = 2010-01-14 TRUE 2nd example: Start Date = 11-22 End Date = 11-16 Start Year = 2009 Specific Date = 2010-11-20 FALSE 3rd example: Start Date = 02-25 End Date = 03-19 Start Year = 2004 Specific Date = 2004-02-29 TRUE I was thinking of using the MySQL functions datediff and sign plus a CASE condition to determine whether the year wraps, but it seems rather expensive. Am looking for a simple, efficient calculation. Update 1 The problem is the end date cannot simply use the year. The year must be increased if the end month/day combination happens before the start date. The start date is easy: Start Date = date( concat_ws( '-', year, Start Month, Start Day ) ) The end date is not so simple. Update 2 Here is what I was thinking about for obtaining the end year: end_year = case sign( diff( date( concat_ws( year, start_month, start_day ) ), date( concat_ws( year, end_month, end_day ) ) ) ) when -1 then Start_Year + 1 else Start_Year end case Then wrap that expression (once syntactically correct) inside of another date, followed by BETWEEN statement. Update 3 To clear up some confusion: there is no end year. The end year must be calculated. Thank you!

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• Is DB logging more secure than file logging for my PHP web app?

  - by iama

  I would like to log errors/informational and warning messages from within my web application to a log. I was initially thinking of logging all of these onto a text file. However, my PHP web app will need write access to the log files and the folder housing this log file may also need write access if log file rotation is desired which my web app currently does not have. The alternative is for me to log the messages to the MySQL database since my web app is already using the MySQL database for all its data storage needs. However, this got me thinking that going with the MySQL option is much better than the file option since I already have a configuration file with the database access information protected using file system permissions. If I now go with the log file option I need to tinker the file and folder access permissions and this will only make my application less secure and defeats the whole purpose of logging. Is this correct? I am using XAMPP for development and am a newbie to LAMP. Please let me know your recommendations for logging. Thanks.

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• How can one convince a team to use a new technology (LinQ, MVC, etc )?

  - by Atomiton

  Obviously, it's easier to do with some developers, but I'm sure many of us are on teams that prefer the status quo. You know the type. You see some benefit in a piece of new technology and they prefer the tried and true methods. Try, for example, DBA/C# programmer the advantages of using LinQ ( not necessarily LinQ to SQL, just LinQ in general ). For example, When a project requirement is to be cross-platform... instead of thinking about how one can run Windows on a Mac through a VM Machine, introducing the idea of using relatively new Silverlight or creating it in Java ( as an option to look into ). I know most people don't like to be out of their comfort level, so it takes a bit of convincing, and not ALL new technology makes business sense... but how have you convinced your team to look at a new technology? What technologies have you successfully introduced to your workplace? What technologies do you think are hardest to introduce? ( I'm thinking paradigm-shifting ones, like MVC from WebForms... or new languages ) What strategies do you employ to make these new technologies appealing?

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• Synchronizing one or more databases with a master database - Foreign keys

  - by Ikke

  I'm using Google Gears to be able to use an application offline (I know Gears is deprecated). The problem I am facing is the synchronization with the database on the server. The specific problem is the primary keys or more exactly, the foreign keys. When sending the information to the server, I could easily ignore the primary keys, and generate new ones. But then how would I know what the relations are. I had one sollution in mind, bet the I would need to save all the pk for every client. What is the best way to synchronize multiple client with one server db. Edit: I've been thinking about it, and I guess seqential primary keys are not the best solution, but what other possibilities are there? Time based doesn't seem right because of collisions which could happen. A GUID comes to mind, is that an option? It looks like generating a GUID in javascript is not that easy. I can do something with natural keys or composite keys. As I'm thinking about it, that looks like the best solution. Can I expect any problems with that?

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• Advanced search engine or server for relational database [closed]

  - by Pawel

  In my current project we are storing big volume of data in relational database. One of the recent key requirements is to enrich application by adding some advanced search capabilities. In the Project, performance is one of the important factors due to very large tables (10+ milions of records) with parent-children relations (for example: multi-level parent-child relationship, where I am looking for all parents with specific children). The search engine should also be able to check these references for hits. I have found some potential engines on stack overflow, however it looks like that all of them are dedicated rather for text search than relational db and hosted on linux os: lucene Solr Sphinx As I understand some of them use documents as a source of searching, but is it possible or efficient to create programmaticaly documents based on my relational data? As I am not familiar with all of their features/capabilities can anyone please make some recommendations or propose some different solution? To summarize my requirements: framework/engine to search relational database including decendants. support for Microsoft SQL Server can be used in .NET applications preferably hosted on Windows systems Does any of mentioned above are able to solve my problem? do you know any better solution?

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• C++ Declarative Parsing Serialization

  - by Martin York

  Looking at Java and C# they manage to do some wicked processing based on special languaged based anotation (forgive me if that is the incorrect name). In C++ we have two problems with this: 1) There is no way to annotate a class with type information that is accessable at runtime. 2) Parsing the source to generate stuff is way to complex. But I was thinking that this could be done with some template meta-programming to achieve the same basic affect as anotations (still just thinking about it). Like char_traits that are specialised for the different types an xml_traits template could be used in a declaritive way. This traits class could be used to define how a class is serialised/deserialized by specializing the traits for the class you are trying to serialize. Example Thoughs: template<typename T> struct XML_traits { typedef XML_Empty Children; }; template<> struct XML_traits<Car> { typedef boost::mpl::vector<Body,Wheels,Engine> Children; }; template<typename T> std::ostream& Serialize(T const&) { // my template foo is not that strong. // but somthing like this. boost::mpl::for_each<typename XML_Traits<T>::Children,Serialize>(data); } template<> std::ostream& Serialize<XML_Empty>(T const&) { /* Do Nothing */ } My question is: Has anybody seen any projects/decumentation (not just XML) out there that uses techniques like this (template meta-programming) to emulate the concept of annotation used in languges like Java and C# that can then be used in code generation (to effectively automate the task by using a declaritive style). At this point in my research I am looking for more reading material and examples.

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• UITableView superClass for delegate?

  - by fuzzygoat

  A quick question, I am setting a delegate for UITableView and I have a question regarding setting the delegate and dataSource properties. I have noticed that the properties for delegate and dataSource are not available, I was thinking that adopting the protocols would make them available. But I am now thinking that I maybe have the superclass for my delegate class wrong. Currently I have: -(void)viewDidLoad { TestDelegate *tempDelegate = [[TestDelegate alloc] init]; [self setMyDelegate:tempDelegate]; // setDelegate // setDataSource [tempDelegate release]; [super viewDidLoad]; } My interface for TestDelegate looks like: @interface TestDelegate : NSObject <UITableViewDelegate, UITableViewDataSource> { NSArray *listData; int myCounter; } Can I ask if the above should be: @interface TestDelegate : UITableView <UITableViewDelegate, UITableViewDataSource> { NSArray *listData; int myCounter; } gary EDIT: I think it might be right as NSObject, I have a viewtableView in IB, thats what I will need to connect my delegate class to. I added to tableView in IB so maybe I just need to make it available in Xcode.

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• Sequential access to asynchronous sockets

  - by Lars A. Brekken

  I have a server that has several clients C1...Cn to each of which there is a TCP connection established. There are less than 10,000 clients. The message protocol is request/response based, where the server sends a request to a client and then the client sends a response. The server has several threads, T1...Tm, and each of these may send requests to any of the clients. I want to make sure that only one of these threads can send a request to a specific client at any one time, while the other threads wanting to send a request to the same client will have to wait. I do not want to block threads from sending requests to different clients at the same time. E.g. If T1 is sending a request to C3, another thread T2 should not be able to send anything to C3 until T1 has received its response. I was thinking of using a simple lock statement on the socket: lock (c3Socket) { // Send request to C3 // Get response from C3 } I am using asynchronous sockets, so I may have to use Monitor instead: Monitor.Enter(c3Socket); // Before calling .BeginReceive() And Monitor.Exit(c3Socket); // In .EndReceive I am worried about stuff going wrong and not letting go of the monitor and therefore blocking all access to a client. I'm thinking that my heartbeat thread could use Monitor.TryEnter() with a timeout and throw out sockets that it cannot get the monitor for. Would it make sense for me to make the Begin and End calls synchronous in order to be able to use the lock() statement? I know that I would be sacrificing concurrency for simplicity in this case, but it may be worth it. Am I overlooking anything here? Any input appreciated.

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• Would an immutable keyword in Java be a good idea?

  - by berry120

  Generally speaking, the more I use immutable objects in Java the more I'm thinking they're a great idea. They've got lots of advantages from automatically being thread-safe to not needing to worry about cloning or copy constructors. This has got me thinking, would an "immutable" keyword go amiss? Obviously there's the disadvantages with adding another reserved word to the language, and I doubt it will actually happen primarily for the above reason - but ignoring that I can't really see many disadvantages. At present great care has to be taken to make sure objects are immutable, and even then a dodgy javadoc comment claiming a component object is immutable when it's in fact not can wreck the whole thing. There's also the argument that even basic objects like string aren't truly immutable because they're easily vunerable to reflection attacks. If we had an immutable keyword the compiler could surely recursively check and give an iron clad guarantee that all instances of a class were immutable, something that can't presently be done. Especially with concurrency becoming more and more used, I personally think it'd be good to add a keyword to this effect. But are there any disadvantages or implementation details I'm missing that makes this a bad idea?

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• Exporting de-aggregated data

  - by Ben

  I'm currently working on a data export feature for a survey application. We are using SQL2k8. We store data in a normalized format: QuestionId, RespondentId, Answer. We have a couple other tables that define what the question text is for the QuestionId and demographics for the RespondentId... Currently I'm using some dynamic SQL to generate a pivot that joins the question table to the answer table and creates an export, its working... The problem is that it seems slow and we don't have that much data (less than 50k respondents). Right now I'm thinking "why am I 'paying' to de-aggregate the data for each query? Why don't I cache that?" The data being exported is based on dynamic criteria. It could be "give me respondents that completed on x date (or range)" or "people that like blue", etc. Because of that, I think I have to cache at the respondent level, find out what respondents are being exported and then select their combined cached de-aggregated data. To me the quick and dirty fix is a totally flat table, RespondentId, Question1, Question2, etc. The problem is, we have multiple clients and that doesn't scale AND I don't want to have to maintain the flattened table as the survey changes. So I'm thinking about putting an XML column on the respondent table and caching the results of a SELECT * FROM Data FOR XML AUTO WHERE RespondentId = x. With that in place, I would then be able to get my export with filtering and XML calls into the XML column. What are you doing to export aggregated data in a flattened format (CSV, Excel, etc)? Does this approach seem ok? I worry about the cost of XML functions on larger result sets (think SELECT RespondentId, XmlCol.value('//data/question_1', 'nvarchar(50)') AS [Why is there air?], XmlCol.RinseAndRepeat)... Is there a better technology/approach for this? Thanks!

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• Generics vs inheritance (when no collection classes are involved)

  - by Ram

  This is an extension of this questionand probably might even be a duplicate of some other question(If so, please forgive me). I see from MSDN that generics are usually used with collections The most common use for generic classes is with collections like linked lists, hash tables, stacks, queues, trees and so on where operations such as adding and removing items from the collection are performed in much the same way regardless of the type of data being stored. The examples I have seen also validate the above statement. Can someone give a valid use of generics in a real-life scenario which does not involve any collections ? Pedantically, I was thinking about making an example which does not involve collections public class Animal<T> { public void Speak() { Console.WriteLine("I am an Animal and my type is " + typeof(T).ToString()); } public void Eat() { //Eat food } } public class Dog { public void WhoAmI() { Console.WriteLine(this.GetType().ToString()); } } and "An Animal of type Dog" will be Animal<Dog> magic = new Animal<Dog>(); It is entirely possible to have Dog getting inherited from Animal (Assuming a non-generic version of Animal)Dog:Animal Therefore Dog is an Animal Another example I was thinking was a BankAccount. It can be BankAccount<Checking>,BankAccount<Savings>. This can very well be Checking:BankAccount and Savings:BankAccount. Are there any best practices to determine if we should go with generics or with inheritance ?

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• Modifying File while in use using Java

  - by Marquinio

  Hi all, I have this recurrent Java JAR program tasks that tries to modify a file every 60seconds. Problem is that if user is viewing the file than Java program will not be able to modify the file. I get the typical IOException. Anyone knows if there is a way in Java to modify a file currently in use? Or anyone knows what would be the best way to solve this problem? I was thinking of using the File canRead(), canWrite() methods to check if file is in use. If file is in use then I'm thinking of making a backup copy of data that could not be written. Then after 60 seconds add some logic to check if backup file is empty or not. If backup file is not empty then add its contents to main file. If empty then just add new data to main file. Of course, the first thing I will always do is check if file is in use. Thanks for all your ideas.

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• Trouble creating a SQL query

  - by JoBu1324

  I've been thinking about how to compose this SQL query for a while now, but after thinking about it for a few hours I thought I'd ask the SO community to see if they have any ideas. Here is a mock up of the relevant portion of the tables: contracts id date ar (yes/no) term payments contract_id payment_date The object of the query is to determine, per month, how many payments we expect, vs how many payments we received. conditions for expecting a payment Expected payments begin on contracts.term months after contracts.date, if contracts.ar is "yes". Payments continue to be expected until the month after the first missed payment. There is one other complication to this: payments might be late, but they need to show up as if they were paid on the date expected. The data is all there, but I've been having trouble wrapping my head around the SQL query. I am not an SQL guru - I merely have a decent amount of experience handling simpler queries. I'd like to avoid filtering the results in code, if possible - but without your help that may be what I have to do. Expected Output Month Expected Payments Received Payments January 500 450 February 498 478 March 234 211 April 987 789 ... SQL Fiddle I've created an SQL Fiddle: http://sqlfiddle.com/#!2/a2c3f/2

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