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  • Highly scalable and dynamic "rule-based" applications?

    - by Prof Plum
    For a large enterprise app, everyone knows that being able to adjust to change is one of the most important aspects of design. I use a rule-based approach a lot of the time to deal with changing business logic, with each rule being stored in a DB. This allows for easy changes to be made without diving into nasty details. Now since C# cannot Eval("foo(bar);") this is accomplished by using formatted strings stored in rows that are then processed in JavaScript at runtime. This works fine, however, it is less than elegant, and would not be the most enjoyable for anyone else to pick up on once it becomes legacy. Is there a more elegant solution to this? When you get into thousands of rules that change fairly frequently it becomes a real bear, but this cannot be that uncommon of a problem that someone has not thought of a better way to do this. Any suggestions? Is this current method defensible? What are the alternatives? Edit: Just to clarify, this is a large enterprise app, so no matter which solution works, there will be plenty of people constantly maintaining its rules and data (around 10). Also, The data changes frequently enough to say that some sort of centralized server system is basically a must.

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  • Why Freezing when sending email?

    - by Outlaw Lemur
    So i have a kinect program which when it detects a human, it saves images of them and sends your email a notification email, the thing is that when it sends the email, it freezes and stops running, Why does it do this? Email Notification Code: void SendNotificationEmail() { string email = textBox1.Text; string message = "Someone has been detected in your house!\n Go to www.kinected.webs.com to view your photos now!!!!"; System.Net.Mail.MailMessage emailsend = new System.Net.Mail.MailMessage(); emailsend.To.Add(email); emailsend.Subject = "There is an Intruder In Your Home!"; emailsend.From = new System.Net.Mail.MailAddress("[email protected]"); emailsend.Body = message; System.Net.Mail.SmtpClient smtp = new System.Net.Mail.SmtpClient("smtp.mail.yahoo.com."); smtp.Send(emailsend); } When its supposed to fire: void nui_ColorFrameReady2(object sender, ImageFrameReadyEventArgs e) { // 32-bit per pixel, RGBA image xxx PlanarImage Image = e.ImageFrame.Image; //int deltaFrames = totalFrames - lastFrameWithMotion; //if (totalFrames2 <= stopFrameNumber & deltaFrames > 300) { ++totalFrames2; string bb1 = Convert.ToString(totalFrames2); // string file_name_3 = "C:\\Research\\Kinect\\Proposal\\Depth_Img" + bb1 + ".jpg"; xxx string file_name_4 = "C:\\temp\\Kinect1_Img" + bb1 + ".jpg"; video.Source = BitmapSource.Create( Image.Width, Image.Height, 96, 96, PixelFormats.Bgr32, null, Image.Bits, Image.Width * Image.BytesPerPixel); BitmapSource image4 = BitmapSource.Create( Image.Width, Image.Height, 96, 96, PixelFormats.Bgr32, null, Image.Bits, Image.Width * Image.BytesPerPixel); if (PersonDetected == 1) { if (totalFrames2 % 10 == 0) { image4.Save(file_name_4, Coding4Fun.Kinect.Wpf.ImageFormat.Jpeg); SendNotificationEmail(); PersonDetected = 0; // lastFrameWithMotion = totalFrames; // topFrameNumber += 100; } } } } Thanks for any help!

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  • High-Level Application Architecture Question

    - by Jesse Bunch
    So I'm really wanting to improve how I architect the software I code. I want to focus on maintainability and clean code. As you might guess, I've been reading a lot of resources on this topic and all it's doing is making it harder for me to settle on an architecture because I can never tell if my design is the one that the more experienced programmer would've chosen. So I have these requirements: I should connect to one vendor and download form submissions from their API. We'll call them the CompanyA. I should then map those submissions to a schema fit for submitting to another vendor for integration with the email service provider. We'll call them the CompanyB. I should then submit those responses to the ESP (CompanyB) and then instruct the ESP to send that submitter an email. So basically, I'm copying data from one web service to another and then performing an action at the latter web service. I've identified a couple high-level services: The service that downloads data from CompanyA. I called this the CompanyAIntegrator. The service that submits the data to CompanyB. I called this CompanyBIntegrator. So my questions are these: Is this a good design? I've tried to separate the concerns and am planning to use the facade pattern to make the integrators interchangeable if the vendors change in the future. Are my naming conventions accurate and meaningful to you (who knows nothing specific of the project)? Now that I have these services, where should I do the work of taking output from the CompanyAIntegrator and getting it in the format for input to the CompanyBIntegrator? Is this OK to be done in main()? Do you have any general pointers on how you'd code something like this? I imagine this scenario is common to us engineers---especially those working in agencies. Thanks for any help you can give. Learning how to architect well is really mind-cluttering.

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  • Database Schema Usage

    - by CrazyHorse
    I have a question regarding the appropriate use of SQL Server database schemas and was hoping that some database gurus might be able to offer some guidance around best practice. Just to give a bit of background, my team has recently shrunk to 2 people and we have just been merged with another 6 person team. My team had set up a SQL Server environment running off a desktop backing up to another desktop (and nightly to the network), whilst the new team has a formal SQL Server environment, running on a dedicated server, with backups and maintenance all handled by a dedicated team. So far it's good news for my team. Now to the query. My team designed all our tables to belong to a 3-letter schema name (e.g. User = USR, General = GEN, Account = ACC) which broadly speaking relate to specific applications, although there is a lot of overlap. My new team has come from an Access background and have implemented their tables within dbo with a 3-letter perfix followed by "_tbl" so the examples above would be dbo.USR_tblTableName, dbo.GEN_tblTableName and dbo.ACC_tblTableName. Further to this, neither my old team nor my new team has gone live with their SQL Servers yet (we're both coincidentally migrating away from Access environments) and the new team have said they're willing to consider adopting our approach if we can explain how this would be beneficial. We are not anticipating handling table updates at schema level, as we will be using application-level logins. Also, with regards to the unwieldiness of the 7-character prefix, I'm not overly concerned myself as we're using LINQ almost exclusively so the tables can simply be renamed in the DMBL (although I know that presents some challenges when we update the DBML). So therefore, given that both teams need to be aligned with one another, can anyone offer any convincing arguments either way?

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  • Constructor vs setter validations

    - by Jimmy
    I have the following class : public class Project { private int id; private String name; public Project(int id, String name, Date creationDate, int fps, List<String> frames) { if(name == null ){ throw new NullPointerException("Name can't be null"); } if(id == 0 ){ throw new IllegalArgumentException("id can't be zero"); } this.name = name; this.id = id; } public int getId() { return id; } public void setId(int id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } } I have three questions: Do I use the class setters instead of setting the fields directly. One of the reason that I set it directly, is that in the code the setters are not final and they could be overridden. If the right way is to set it directly and I want to make sure that the name filed is not null always. Should I provide two checks, one in the constructor and one in the setter. I read in effective java that I should use NullPointerException for null parameters. Should I use IllegalArgumentException for other checks, like id in the example.

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  • Books for MCSD and advice

    - by Mahesha999
    Hi there I am thinking to get certification done for MCSD. http://www.microsoft.com/learning/en/us/certification/cert-mcsd-web-applications.aspx I did found the books for first exam 480 comprising CSS3, HTML5 and JavaScript. However I did not found books for other exams: 486: ASP.NET MVC 4.5 Apps - Will ASP.NET 4 books suffice for this? Should I also learn Web Forms though I have considerable part of it. 487: Windows Azure and Web Services - What book should I use? I seems that the syllabus is too huge and will take considerable time. Anyone suggesting any advice to complete such exams, since this is going to be my first such. How should I prepare? Should I give this exam? Will it help? Sorry I know I asked many questions here in one questions - a bad practice but the books-question is a big concern for me.

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  • Adding a forum to an existing site

    - by Andrew Heath
    I've got a site with ~500 registered members, 300 of which are what you'd call "active". Site data is kept in a MySQL dbase. I'd like to add a myBB forum to the site, but this question applies to any forum really. What I very much want to avoid is requiring my users to register both on the site and on the forum because my userbase is not technically literate and this would confuse a lot of them. However the forum software has its own registration, login, cookie, and password management system which naturally are different from the site's mechanics. I envision the following possibilities: install myBB into the existing database and customize the login code to unify the two systems. This would probably mean changing the site's code to use the myBB system as that would likely be less painful to refactor and wouldn't hurt future myBB upgrade ability. install myBB into separate database and write a bridging script of some sort that auto-registers existing site users with the forum if they elect to participate. Also check new forum registrations against the site's username list to prevent newcomers from taking existing names. run them fully separate and force users to re-register (easiest for ME, but least desirable for them) I would like a suggested course of action from those who have trod this path before... Thank you.

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  • What is a best practice tier structure of a Java EE 6/7 application?

    - by James Drinkard
    I was attempting to find a best practice for modeling the tiers in a Java EE application yesterday and couldn't come up with anything current. In the past, say java 1.4, it was four tiers: Presentation Tier Web Tier Business Logic Tier DAL (Data Access Layer ) which I always considered a tier and not a layer. After working with Web Services and SOA I thought to add in a services tier, but that may fall under 3. the business logic tier. I did searches for quite a while and reading articles. It seems like Domain Driven Design is becoming more popular, but I couldn't find a diagram on it's tier structure. Anyone have ideas or diagrams on what the proper tier structure is for newer Java EE applications or is it really the same, but more items are ranked under the four I've mentioned?

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  • What was your most challenging project? and why? [closed]

    - by tau
    I am asked this question many times in the interviews. I get confused about which project to tell them and why some project would look challenging or non-challenging. What are they looking for in the answer? Any software is a challenge before it gets started and it becomes a normal software engineering task after it has finished. All softwares I made were challenging until they got finished. Do I misunderstood the word "challenge"? Whats wrong in my thinking? What was your most challenging project and why you think so?

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  • What is the most accurate/frequent report on browser usage on the Internet?

    - by Ryan Hayes
    I'm determining which browsers a new site should support. I'm looking for a respected and accurate (as possible) report on the browser versions that are currently in use. This report should, at minimum cover the % of people who use what browsers, and versions of that browser. Is there a widely accepted source for this kind of report? If so, are they regularly released and available for free? Bonus points for other metrics such as breaking down by OS, Flash versions, JS versions, etc.

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  • What is up with the Joy of Clojure 2nd edition?

    - by kurofune
    Manning just released the second edition of the beloved Joy of Clojure book, and while I share that love I get the feeling that many of the examples are already outdated. In particular, in the chapter on optimization the recommended type-hinting seems not to be allowed by the compiler. I don't know if this was allowable for older versions of Clojure. For example: (defn factorial-f [^long original-x] (loop [x original-x, acc 1] (if (>= 1 x) acc (recur (dec x) (*' x acc))))) returns: clojure.lang.Compiler$CompilerException: java.lang.UnsupportedOperationException: Can't type hint a primitive local, compiling:(null:3:1) Likewise, the chapter on core.logic seems be using an old API and I have to find workarounds for each example to accommodate the recent changes. For example, I had to turn this: (logic/defrel orbits orbital body) (logic/fact orbits :mercury :sun) (logic/fact orbits :venus :sun) (logic/fact orbits :earth :sun) (logic/fact orbits :mars :sun) (logic/fact orbits :jupiter :sun) (logic/fact orbits :saturn :sun) (logic/fact orbits :uranus :sun) (logic/fact orbits :neptune :sun) (logic/run* [q] (logic/fresh [orbital body] (orbits orbital body) (logic/== q orbital))) into this, leveraging the pldb lib: (pldb/db-rel orbits orbital body) (def facts (pldb/db [orbits :mercury :sun] [orbits :venus :sun] [orbits :earth :sun] [orbits :mars :sun] [orbits :jupiter :sun] [orbits :saturn :sun] [orbits :uranus :sun] [orbits :neptune :sun])) (pldb/with-db facts (logic/run* [q] (logic/fresh [orbital body] (orbits orbital body) (logic/== q orbital)))) I am still pulling teeth to get the later examples to work. I am relatively new programming, myself, so I wonder if I am naively looking over something here, or are if these points I'm making legitimate concerns? I really want to get good at this stuff like type-hinting and core.logic, but wanna make sure I am studying up to date materials. Any illuminating facts to help clear up my confusion would be most welcome.

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  • Jr developer report bug to maybe futur boss

    - by Cryptoforce
    I applied for a Web developer job in Quebec City and they call me back for a phone interview everything went well it last for over a hours and at the end they ask me to send code simple and a portfolio but in my research about the company and their products I found a PHP error(bug) in their app. Should I tell them or I will look like a total jerk and blew my chance for a interview? I know it might sound stupid, as a Jr developer I did 2 interviews they didn't went so well and I am very interested in this position part of my question is like a big lack of confidence so to make it short should I tell them about where is the error and how to fix it? Thanks

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  • How to ask the boss to pay for training courses

    - by jiceo
    Recently I came upon a well known local consulting company that has some interesting courses I'd like to take. The course is not cheap enough for me to pay out of my own pocket and not feel bad afterwards. The thing is that my startup company uses one set of framework (Python+Django) for most of the stuff I have to deal with, but the course covers Ruby on Rails 3. Since I've not had exposure to Ruby on Rails, and after seeing so many people speak highly of the course, I really thought it would be a good opportunity. I know that I'd have to approach my boss at the angle of 'how this might benefit the company' but other than this, any suggestions?

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  • Should I comment Tables or Columns in my database?

    - by jako
    I like to comment my code with various information, and I think most people nowadays do so while writing some code. But when it comes to database tables or columns, I have never seen anyone setting some comments, and, to be honest, I don't even think of looking for comments there. So I am wondering if some people are commenting their DB strcuture here, and if I should bother commenting, for instance when I create a new column to an existing table?

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  • Is sticking to one language a good practice?

    - by Ans
    I'm developing a pipeline for processing text that will go into production. The question I keep asking myself is: should I stick to one language when looking for a tool to do a particular task (e.g. NLTK, PDFMiner, CLD, CRFsuite, etc.)? Or is it OK to mix and match looking for the best tool regardless of what language it's written in (e.g. OpenNLP, ParsCit, poppler, CFR++, etc.) and warp my code around them?

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  • Why no fortran standard library ?

    - by Stefano Borini
    To be a language focused on mathematics and scientific computing, I am always baffled by the total lack of useful mathematical routines in the Fortran standard library. One would expect it to be shipped at least with a routine to compute standard deviation and mean, but this is not the case. In particular with the introduction of Fortran 90 and the addition of modules (thus reducing namespace pollution), I don't see any reason why of this critical lack of services. I would like to hear your knowledge about why this is the case.

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  • Is extreme programming out of date?

    - by KingBabar
    I have stumbled across this graph and I wonder if someone would care to explain the results? As you can see, extreme programming (XP) is practically uninterested and has almost disappeared from searches. The legend is: Blue: Agile Red: Scrum Orange: extreme programming Green: Waterfall source: http://www.google.com/insights/search/#cat=0-5&q=agile%2Cscrum%2Cextreme%20programming%2Cwaterfall&cmpt=q

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  • Class Design -- Multiple Calls from One Method or One Call from Multiple Methods?

    - by Andrew
    I've been working on some code recently that interfaces with a CMS we use and it's presented me with a question on class design that I think is applicable in a number of situations. Essentially, what I am doing is extracting information from the CMS and transforming this information into objects that I can use programatically for other purposes. This consists of two steps: Retrieve the data from the CMS (we have a DAL that I use, so this is essentially just specifying what data from the CMS I want--no connection logic or anything like that) Map the parsed data to my own [C#] objects There are basically two ways I can approach this: One call from multiple methods public void MainMethodWhereIDoStuff() { IEnumerable<MyObject> myObjects = GetMyObjects(); // Do other stuff with myObjects } private static IEnumerable<MyObject> GetMyObjects() { IEnumerable<CmsDataItem> cmsDataItems = GetCmsDataItems(); List<MyObject> mappedObjects = new List<MyObject>(); // do stuff to map the CmsDataItems to MyObjects return mappedObjects; } private static IEnumerable<CmsDataItem> GetCmsDataItems() { List<CmsDataItem> cmsDataItems = new List<CmsDataItem>(); // do stuff to get the CmsDataItems I want return cmsDataItems; } Multiple calls from one method public void MainMethodWhereIDoStuff() { IEnumerable<CmsDataItem> cmsDataItems = GetCmsDataItems(); IEnumerable<MyObject> myObjects = GetMyObjects(cmsDataItems); // do stuff with myObjects } private static IEnumerable<MyObject> GetMyObjects(IEnumerable<CmsDataItem> itemsToMap) { // ... } private static IEnumerable<CmsDataItem> GetCmsDataItems() { // ... } I am tempted to say that the latter is better than the former, as GetMyObjects does not depend on GetCmsDataItems, and it is explicit in the calling method the steps that are executed to retrieve the objects (I'm concerned that the first approach is kind of an object-oriented version of spaghetti code). On the other hand, the two helper methods are never going to be used outside of the class, so I'm not sure if it really matters whether one depends on the other. Furthermore, I like the fact that in the first approach the objects can be retrieved from one line-- most likely anyone working with the main method doesn't care how the objects are retrieved, they just need to retrieve the objects, and the "daisy chained" helper methods hide the exact steps needed to retrieve them (in practice, I actually have a few more methods but am still able to retrieve the object collection I want in one line). Is one of these methods right and the other wrong? Or is it simply a matter of preference or context dependent?

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  • How do I express subtle relationships in my data?

    - by Chuck H
    "A" is related to "B" and "C". How do I show that "B" and "C" might, by this context, be related as well? Example: Here are a few headlines about a recent Broadway play: 1 - David Mamet's Glengarry Glen Ross, Starring Al Pacino, Opens on Broadway 2 - Al Pacino in 'Glengarry Glen Ross': What did the critics think? 3 - Al Pacino earns lackluster reviews for Broadway turn 4 - Theater Review: Glengarry Glen Ross Is Selling Its Stars Hard 5 - Glengarry Glen Ross; Hey, Who Killed the Klieg Lights? Problem: Running a fuzzy-string match over these records will establish some relationships, but not others, even though a human reader could pick them out from context in much larger datasets. How do I find the relationship that suggests #3 is related to #4? Both of them can be easily connected to #1, but not to each other. Is there a (Googlable) name for this kind of data or structure? What kind of algorithm am I looking for? Goal: Given 1,000 headlines, a system that automatically suggests that these 5 items are all probably about the same thing. To be honest, it's been so long since I've programmed I'm at a loss how to properly articulate this problem. (I don't know what I don't know, if that makes sense). This is a personal project and I'm writing it in Python. Thanks in advance for any help, advice, and pointers!

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  • Code Style - Do you prefer to return from a function early or just use an IF statement?

    - by Rachel
    I've often written this sort of function in both formats, and I was wondering if one format is preferred over another, and why. public void SomeFunction(bool someCondition) { if (someCondition) { // Do Something } } or public void SomeFunction(bool someCondition) { if (!someCondition) return; // Do Something } I usually code with the first one since that is the way my brain works while coding, although I think I prefer the 2nd one since it takes care of any error handling right away and I find it easier to read

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  • How to convince my boss that quality is a good thing to have in code?

    - by Kristof Claes
    My boss came to me today to ask me if we could implement a certain feature in 1.5 days. I had a look at it and told him that 2 to 3 days would be more realistic. He then asked me: "And what if we do it quick and dirty?" I asked him to explain what he meant with "quick and dirty". It turns out, he wants us to write code as quickly as humanly possible by (for example) copying bits and pieces from other projects, putting all code in the code-behind of the WebForms pages, stop caring about DRY and SOLID and assuming that the code and functionalities will never ever have to be modified or changed. What's even worse, he doesn't want us do it for just this one feature, but for all the code we write. We can make more profit when we do things quick and dirty. Clients don't want to pay for you taking into account that something might change in the future. The profits for us are in delivering code as quick as possible. As long as the application does what it needs to do, the quality of the code doesn't matter. They never see the code. I have tried to convince him that this is a bad way to think as the manager of a software company, but he just wouldn't listen to my arguments: Developer motivation: I explained that it is hard to keep developers motivated when they are constantly under pressure of unrealistic deadlines and budget to write sloppy code very quickly. Readability: When a project gets passed on to another developer, cleaner and better structured code will be easier to read and understand. Maintainability: It is easier, safer and less time consuming to adapt, extend or change well written code. Testability: It is usually easier to test and find bugs in clean code. My co-workers are as baffled as I am by my boss' standpoint, but we can't seem to get to him. He keeps on saying that by making things more quickly, we can sell more projects, ask a lower price for them while still making a bigger profit. And in the end these projects pay the developer's salaries. What more can I say to make him see he is wrong? I want to buy him copies of Peopleware and The Mythical Man-Month, but I have a feeling they won't change his mind either. A lot of you will probably say something like "Run! Get out of there now!" or "I'd quit!", but that's not really an option since .NET web development jobs are rather rare in the region where I live...

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  • Is this proper OO design for C++?

    - by user121917
    I recently took a software processes course and this is my first time attempting OO design on my own. I am trying to follow OO design principles and C++ conventions. I attempted and gave up on MVC for this application, but I am trying to "decouple" my classes such that they can be easily unit-tested and so that I can easily change the GUI library used and/or the target OS. At this time, I have finished designing classes but have not yet started implementing methods. The function of the software is to log all packets sent and received, and display them on the screen (like WireShark, but for one local process only). The software accomplishes this by hooking the send() and recv() functions in winsock32.dll, or some other pair of analogous functions depending on what the intended Target is. The hooks add packets to SendPacketList/RecvPacketList. The GuiLogic class starts a thread which checks for new packets. When new packets are found, it utilizes the PacketFilter class to determine the formatting for the new packet, and then sends it to MainWindow, a native win32 window (with intent to later port to Qt).1 Full size image of UML class diagram Here are my classes in skeleton/header form (this is my actual code): class PacketModel { protected: std::vector<byte> data; int id; public: PacketModel(); PacketModel(byte* data, unsigned int size); PacketModel(int id, byte* data, unsigned int size); int GetLen(); bool IsValid(); //len >= sizeof(opcode_t) opcode_t GetOpcode(); byte* GetData(); //returns &(data[0]) bool GetData(byte* outdata, int maxlen); void SetData(byte* pdata, int len); int GetId(); void SetId(int id); bool ParseData(char* instr); bool StringRepr(char* outstr); byte& operator[] (const int index); }; class SendPacket : public PacketModel { protected: byte* returnAddy; public: byte* GetReturnAddy(); void SetReturnAddy(byte* addy); }; class RecvPacket : public PacketModel { protected: byte* callAddy; public: byte* GetCallAddy(); void SetCallAddy(byte* addy); }; //problem: packets may be added to list at any time by any number of threads //solution: critical section associated with each packet list class Synch { public: void Enter(); void Leave(); }; template<class PacketType> class PacketList { private: static const int MAX_STORED_PACKETS = 1000; public: static const int DEFAULT_SHOWN_PACKETS = 100; private: vector<PacketType> list; Synch synch; //wrapper for critical section public: void AddPacket(PacketType* packet); PacketType* GetPacket(int id); int TotalPackets(); }; class SendPacketList : PacketList<SendPacket> { }; class RecvPacketList : PacketList<RecvPacket> { }; class Target //one socket { bool Send(SendPacket* packet); bool Inject(RecvPacket* packet); bool InitSendHook(SendPacketList* sendList); bool InitRecvHook(RecvPacketList* recvList); }; class FilterModel { private: opcode_t opcode; int colorID; bool bFilter; char name[41]; }; class FilterFile { private: FilterModel filter; public: void Save(); void Load(); FilterModel* GetFilter(opcode_t opcode); }; class PacketFilter { private: FilterFile filters; public: bool IsFiltered(opcode_t opcode); bool GetName(opcode_t opcode, char* namestr); //return false if name does not exist COLORREF GetColor(opcode_t opcode); //return default color if no custom color }; class GuiLogic { private: SendPacketList sendList; RecvPacketList recvList; PacketFilter packetFilter; void GetPacketRepr(PacketModel* packet); void ReadNew(); void AddToWindow(); public: void Refresh(); //called from thread void GetPacketInfo(int id); //called from MainWindow }; I'm looking for a general review of my OO design, use of UML, and use of C++ features. I especially just want to know if I'm doing anything considerably wrong. From what I've read, design review is on-topic for this site (and off-topic for the Code Review site). Any sort of feedback is greatly appreciated. Thanks for reading this.

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  • How does I/O work for large graph databases?

    - by tjb1982
    I should preface this by saying that I'm mostly a front end web developer, trained as a musician, but over the past few years I've been getting more and more into computer science. So one idea I have as a fun toy project to learn about data structures and C programming was to design and implement my own very simple database that would manage an adjacency list of posts. I don't want SQL (maybe I'll do my own query language? I'm just having fun). It should support ACID. It should be capable of storing 1TB let's say. So with that, I was trying to think of how a database even stores data, without regard to data structures necessarily. I'm working on linux, and I've read that in that world "everything is a file," including hardware (like /dev/*), so I think that that obviously has to apply to a database, too, and it clearly does--whether it's MySQL or PostgreSQL or Neo4j, the database itself is a collection of files you can see in the filesystem. That said, there would come a point in scale where loading the entire database into primary memory just wouldn't work, so it doesn't make sense to design it with that mindset (I assume). However, reading from secondary memory would be much slower and regardless some portion of the database has to be in primary memory in order for you to be able to do anything with it. I read this post: Why use a database instead of just saving your data to disk? And I found it difficult to understand how other databases, like SQLite or Neo4j, read and write from secondary memory and are still very fast (faster, it would seem, than simply writing files to the filesystem as the above question suggests). It seems the key is indexing. But even indexes need to be stored in secondary memory. They are inherently smaller than the database itself, but indexes in a very large database might be prohibitively large, too. So my question is how is I/O generally done with large databases like the one I described above that would be at least 1TB storing a big adjacency list? If indexing is more or less the answer, how exactly does indexing work--what data structures should be involved?

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  • how to develop a common pool of functions?

    - by user975234
    I need to develop an application which runs on the web as well as on mobile platform. I want to make something like a directory where i hold my common functions in respect to web and mobile platform. This is the diagram which describes what i exactly want: I just want to know how do i implement this thing? If you can help me with the technical details that would be great! P.S: I am new to web app and stuff!

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  • Is .NET WCF worth the effort?

    - by SnOrfus
    Maybe it's me, but I've never encountered nearly as many problems, annoying challenges, indirect error messages and general frustrations with any other technology as I have with WCF. What are the ACTUAL benefits? Not the MS Press Release benefits of 'a unified architecture for something something that's not going to work anyway.' And are those benefits worth the annoying frustrations? I'm normally a big MS fanboy over here, but I just can't get behind WCF.

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