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• Object Oriented Programming in AS3

  - by Jordan

  I'm building a game in as3 that has balls moving and bouncing off the walls. When the user clicks an explosion appears and any ball that hits that explosion explodes too. Any ball that then hits that explosion explodes and so on. My question is what would be the best class structure for the balls. I have a level system to control levels and such and I've already come up with working ways to code the balls. Here's what I've done. My first attempt was to create a class for Movement, Bounce, Explosion and finally Orb. These all extended each other in the order I just named them. I got it working but having Bounce extend Movement and Explosion extend Bounce, it just doesn't seem very object oriented because what if I wanted to add a box class that didn't move, but did explode? I would need a separate class for that explosion. My second attempt was to create Movement, Bounce and Explosion without extending anything. Instead I passed in a reference to the Orb class to each. Then the class stores that reference and does what it needs to do based on events that are dispatched by the Orb such as update, which was broadcast from Orb every enter frame. This would drive the movement and bounce and also the explosion when the time came. This attempt worked as well but it just doesn't seem right. I've also thought about using Interfaces but because they are more of an outline for classes, I feel like code reuse goes out the window as each class would need its own code for a specific task even if that task is exactly the same. I feel as if I'm searching for some form of multiple inheritance for classes that as3 does not support. Can someone explain to me a better way of doing what I'm attempting to do? Am I being to "Object Oriented" by having classed for Movement, Bounce, Explosion and Orb? Are Interfaces the way to go? Any feedback is appreciated!

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• Java library class to handle scheduled execution of "callbacks"?

  - by Hanno Fietz

  My program has a component - dubbed the Scheduler - that lets other components register points in time at which they want to be called back. This should work much like the Unix cron service, i. e. you tell the Scheduler "notify me at ten minutes past every full hour". I realize there are no real callbacks in Java. Here's my approach, is there a library which already does this stuff? Feel free to suggest improvements, too. Register call to Scheduler passes: a time specification containing hour, minute, second, year month, dom, dow, where each item may be unspecified, meaning "execute it every hour / minute etc." (just like crontabs) an object containing data that will tell the calling object what to do when it is notified by the Scheduler. The Scheduler does not process this data, just stores it and passes it back upon notification. a reference to the calling object Upon startup, or after a new registration request, the Scheduler starts with a Calendar object of the current system time and checks if there are any entries in the database that match this point in time. If there are, they are executed and the process starts over. If there aren't, the time in the Calendar object is incremented by one second and the entreis are rechecked. This repeats until there is one entry or more that match(es). (Discrete Event Simulation) The Scheduler will then remember that timestamp, sleep and wake every second to check if it is already there. If it happens to wake up and the time has already passed, it starts over, likewise if the time has come and the jobs have been executed. Edit: Thanks for pointing me to Quartz. I'm looking for something much smaller, however.

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• When is it better to use a method versus a property for a class definition?

  - by ccomet

  Partially related to an earlier question of mine, I have a system in which I have to store complex data as a string. Instead of parsing these strings as all kinds of separate objects, I just created one class that contains all of those objects, and it has some parser logic that will encode all properties into strings, or decode a string to get those objects. That's all fine and good. This question is not about the parser itself, but about where I should house the logic for the parser. Is it a better choice to put it as a property, or as a method? In the case of a property, say public string DataAsString, the get accessor would house the logic to encode all of the data into a string, while the set accessor would decode the input value and set all of the data in the class instance. It seems convenient because the input/output is indeed a string. In the case of a method, one method would be Encode(), which returns the encoded string. Then, either the constructor itself would house the logic for the decoding a string and require the string argument, or I write a Decode(string str) method which is called separately. In either case, it would be using a method instead of a property. So, is there a functional difference between these paths, in terms of the actual running of the code? Or are they basically equivalent and it then boils down to a choice of personal preference or which one looks better? And in that kind of question... which would look cleaner anyway?

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• Upgrade .NET 1.1 WinForm/Service to what?

  - by Conor

  Hi Folks, We have a current WinForm/Windows Service running in .NET 1.1 out on various customer sites that is getting data from internal systems, transforming it and then calling a Web Service synchronously. This client app will no longer work in Vista or Windows 7 etc.. and its time to update!! I was looking for ideas on what I could do here, I didn't write the App and I have the Business team telling me they want the world but I need to be realistic :) Things the service must be able to do: - Handle multiple formats from internal system and transform to a schema SAP, ERP etc.. - Run silently and just work on customer sites (it does currently albeit .NET 1.1) - The Customers are unable to call our web service from their sites as they are not technical enough. - Upgrade it's self when updates occur (currently don't have this capability) Is there anything I can do here other than upgrade the service to run in .NET and add a few more transformation capabilities e..g they want the customer to be able to give us a flat file, an xml file, a csv and the service transforms it and calls the Web Service? I was hoping in this day and age we could use the Web, but automating this 100% rules it out in my eyes? I could be totally wrong!! Any help would be gratefully appreciated! Cheers. Conor

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• Need some help understanding this problem

  - by Legend

  I was wondering if someone could help me understand this problem. I prepared a small diagram because it is much easier to explain it visually. Problem I am trying to solve: 1. Constructing the dependency graph Given the connectivity of the graph and a metric that determines how well a node depends on the other, order the dependencies. For instance, I could put in a few rules saying that node 3 depends on node 4 node 2 depends on node 3 node 3 depends on node 5 But because the final rule is not "valuable" (again based on the same metric), I will not add the rule to my system. 2. Execute the request order Once I built a dependency graph, execute the list in an order that maximizes the final connectivity. First and foremost, I am wondering if I constructed the problem correctly and if I should be aware of any corner cases. Secondly, is there a closely related algorithm that I can look at? Currently, I am thinking of something like Feedback Arc Set or the Secretary Problem but I am a little confused at the moment. Any suggestions? PS: I am a little confused about the problem myself so please don't flame on me for that. If any clarifications are needed, I will try to update the question.

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• What is the best way to store site configuration data?

  - by DaveDev

  I have a question about storing site configuration data. We have a platform for web applications. The idea is that different clients can have their data hosted and displayed on their own site which sits on top of this platform. Each site has a configuration which determines which panels relevant to the client appear on which pages. The system was originally designed to keep all the configuration data for each site in a database. When the site is loaded all the configuration data is loaded into a SiteConfiguration object, and the clients panels are generated based on the content of this object. This works, but I find it very difficult to work with to apply change requests or add new sites because there is so much data to sift through and it's difficult maintain a mental model of the site and its configuration. Recently I've been tasked with developing a subset of some of the sites to be generated as PDF documents for printing. I decided to take a different approach to how I would define the configuration in that instead of storing configuration data in the database, I wrote XML files to contain the data. I find it much easier to work with because instead of reading meaningless rows of data which are related to other meaningless rows of data, I have meaningful documents with semantic, readable information with the relationships defined by visually understandable element nesting. So now with these 2 approaches to storing site configuration data, I'd like to get the opinions of people more experienced in dealing with this issue on dealing with these two approaches. What is the best way of storing site configuration data? Is there a better way than the two ways I outlined here? note: StackOverflow is telling me the question appears to be subjective and is likely to be closed. I'm not trying to be subjective. I'd like to know how best to approach this issue next time and if people with industry experience on this could provide some input.

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• No value given for one or more required parameters in connection initialisation

  - by Jean-François Côté

  I have an C# form application that use an access database. This application works perfectly in debug and release. It works on all version of Windows. But it crash on one computer with Windows 7. The message I got is: System.Data.OleDb.OleDbException: No value given for one or more required parameters. EDIT, after some debugging with messagebox on the computer that have the problem, here is the code that bug.The error is catched on the cmd.ExecuteReader(). The messagebox juste before is shown and the next one is the one in the catch with the exception below. Any ideas? public List<CoeffItem> GetModeleCoeff() { List<CoeffItem> list = new List<CoeffItem>(); try { OleDbDataReader dr; OleDbCommand cmd = new OleDbCommand("SELECT nIDModelAquacad, nIDModeleBorne, fCoefficient FROM tbl_ModelBorne ORDER BY nIDModelAquacad", m_conn); MessageBox.Show("Commande SQL créée avec succès"); dr = cmd.ExecuteReader(); MessageBox.Show("Exécution du reader sans problème!"); while (dr.Read()) { list.Add(new CoeffItem(Convert.ToInt32(dr["nIDModelAquacad"].ToString()), Convert.ToInt32(dr["nIDModeleBorne"].ToString()), Convert.ToDouble(dr["fCoefficient"].ToString()))); } MessageBox.Show("Lecture du reader"); dr.Close(); MessageBox.Show("Fermeture du reader"); } catch (OleDbException err) { MessageBox.Show("Erreur dans la lecture des modèles/coefficient: " + err.ToString()); } return list; } I think it's something related to the connection string but why only on that computer. Thanks for your help! EDIT Here is the complete error message: See the end of this message for details on invoking just-in-time (JIT) debugging instead of this dialog box. ***** Exception Text ******* System.Data.OleDb.OleDbException: No value given for one or more required parameters. at System.Data.OleDb.OleDbCommand.ExecuteCommandTextErrorHandling(OleDbHResult hr) at System.Data.OleDb.OleDbCommand.ExecuteCommandTextForSingleResult(tagDBPARAMS dbParams, Object& executeResult) at System.Data.OleDb.OleDbCommand.ExecuteCommandText(Object& executeResult) at System.Data.OleDb.OleDbCommand.ExecuteCommand(CommandBehavior behavior, Object& executeResult) at System.Data.OleDb.OleDbCommand.ExecuteReaderInternal(CommandBehavior behavior, String method) at System.Data.OleDb.OleDbCommand.ExecuteReader(CommandBehavior behavior) at System.Data.OleDb.OleDbCommand.ExecuteReader() at DatabaseLayer.DatabaseFacade.GetModeleCoeff() at DatabaseLayer.DatabaseFacade.InitConnection(String strFile) at CalculatriceCHW.ListeMesure.OuvrirFichier(String strFichier) at CalculatriceCHW.ListeMesure.nouveauFichierMenu_Click(Object sender, EventArgs e) at System.Windows.Forms.ToolStripItem.RaiseEvent(Object key, EventArgs e) at System.Windows.Forms.ToolStripMenuItem.OnClick(EventArgs e) at System.Windows.Forms.ToolStripItem.HandleClick(EventArgs e) at System.Windows.Forms.ToolStripItem.HandleMouseUp(MouseEventArgs e) at System.Windows.Forms.ToolStripItem.FireEventInteractive(EventArgs e, ToolStripItemEventType met) at System.Windows.Forms.ToolStripItem.FireEvent(EventArgs e, ToolStripItemEventType met) at System.Windows.Forms.ToolStrip.OnMouseUp(MouseEventArgs mea) at System.Windows.Forms.ToolStripDropDown.OnMouseUp(MouseEventArgs mea) at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks) at System.Windows.Forms.Control.WndProc(Message& m) at System.Windows.Forms.ScrollableControl.WndProc(Message& m) at System.Windows.Forms.ToolStrip.WndProc(Message& m) at System.Windows.Forms.ToolStripDropDown.WndProc(Message& m) at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m) at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m) at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

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• Auto increment with a Unit Of Work

  - by Derick

  Context I'm building a persistence layer to abstract different types of databases that I'll be needing. On the relational part I have mySQL, Oracle and PostgreSQL. Let's take the following simplified MySQL tables: CREATE TABLE Contact ( ID varchar(15), NAME varchar(30) ); CREATE TABLE Address ( ID varchar(15), CONTACT_ID varchar(15), NAME varchar(50) ); I use code to generate system specific alpha numeric unique ID's fitting 15 chars in this case. Thus, if I insert a Contact record with it's Addresses I have my generated Contact.ID and Address.CONTACT_IDs before committing. I've created a Unit of Work (amongst others) as per Martin Fowler's patterns to add transaction support. I'm using a key based Identity Map in the UoW to track the changed records in memory. It works like a charm for the scenario above, all pretty standard stuff so far. The question scenario comes in when I have a database that is not under my control and the ID fields are auto-increment (or in Oracle sequences). In this case I do not have the db generated Contact.ID beforehand, so when I create my Address I do not have a value for Address.CONTACT_ID. The transaction has not been started on the DB session since all is kept in the Identity Map in memory. Question: What is a good approach to address this? (Avoiding unnecessary db round trips) Some ideas: Retrieve the last ID: I can do a call to the database to retrieve the last Id like: SELECT Auto_increment FROM information_schema.tables WHERE table_name='Contact'; But this is MySQL specific and probably something similar can be done for the other databases. If do this then would need to do the 1st insert, get the ID and then update the children (Address.CONTACT_IDs) – all in the current transaction context.

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• Are bad data issues that common?

  - by Water Cooler v2

  I've worked for clients that had a large number of distinct, small to mid-sized projects, each interacting with each other via properly defined interfaces to share data, but not reading and writing to the same database. Each had their own separate database, their own cache, their own file servers/system that they had dedicated access to, and so they never caused any problems. One of these clients is a mobile content vendor, so they're lucky in a way that they do not have to face the same problems that everyday business applications do. They can create all those separate compartments where their components happily live in isolation of the others. However, for many business applications, this is not possible. I've worked with a few clients, one of whose applications I am doing the production support for, where there are "bad data issues" on an hourly basis. Yeah, it's that crazy. Some data records from one of the instances (lower than production, of course) would have been run a couple of weeks ago, and caused some other user's data to get corrupted. And then, a data script will have to be written to fix this issue. And I've seen this happening so much with this client that I have to ask. I've seen this happening at a moderate rate with other clients, but this one just seems to be out of order. If you're working with business applications that share a large amount of data by reading and writing to/from the same database, are "bad data issues" that common in your environment?

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• Generic version control strategy for select table data within a heavily normalized database

  - by leppie

  Hi Sorry for the long winded title, but the requirement/problem is rather specific. With reference to the following sample (but very simplified) structure (in psuedo SQL), I hope to explain it a bit better. TABLE StructureName { Id GUID PK, Name varchar(50) NOT NULL } TABLE Structure { Id GUID PK, ParentId GUID (FK to Structure), NameId GUID (FK to StructureName) NOT NULL } TABLE Something { Id GUID PK, RootStructureId GUID (FK to Structure) NOT NULL } As one can see, Structure is a simple tree structure (not worried about ordering of children for the problem). StructureName is a simplification of a translation system. Finally 'Something' is simply something referencing the tree's root structure. This is just one of many tables that need to be versioned, but this one serves as a good example for most cases. There is a requirement to version to any changes to the name and/or the tree 'layout' of the Structure table. Previous versions should always be available. There seems to be a few possibilities to tackle this issue, like copying the entire structure, but most approaches causes one to 'loose' referential integrity. Example if one followed this approach, one would have to make a duplicate of the 'Something' record, given that the root structure will be a new record, and have a new ID. Other avenues of possible solutions are looking into how Wiki's handle this or go a lot further and look how proper version control systems work. Currently, I feel a bit clueless how to proceed on this in a generic way. Any ideas will be greatly appreciated. Thanks leppie

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• Function returning a class containing a function returning a class

  - by Scott

  I'm working on an object-oriented Excel add-in to retrieve information from our ERP system's database. Here is an example of a function call: itemDescription = Macola.Item("12345").Description Macola is an instance of a class which takes care of database access. Item() is a function of the Macola class which returns an instance of an ItemMaster class. Description() is a function of the ItemMaster class. This is all working correctly. Items can be be stored in more than one location, so my next step is to do this: quantityOnHand = Macola.Item("12345").Location("A1").QuantityOnHand Location() is a function of the ItemMaster class which returns an instance of the ItemLocation class (well, in theory anyway). QuantityOnHand() is a function of the ItemLocation class. But for some reason, the ItemLocation class is not even being intialized. Public Function Location(inventoryLocation As String) As ItemLocation Set Location = New ItemLocation Location.Item = item_no Location.Code = inventoryLocation End Function In the above sample, the variable item_no is a member variable of the ItemMaster class. Oddly enough, I can successfully instantiate the ItemLocation class outside of the ItemMaster class in a non-class module. Dim test As New ItemLocation test.Item = "12345" test.Code = "A1" quantityOnHand = test.QuantityOnHand Is there some way to make this work the way I want? I'm trying to keep the API as simple as possible. So that it only takes one line of code to retrieve a value.

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• PHP static objects giving a fatal error

  - by Webbo

  I have the following PHP code; <?php component_customer_init(); component_customer_go(); function component_customer_init() { $customer = Customer::getInstance(); $customer->set(1); } function component_customer_go() { $customer = Customer::getInstance(); $customer->get(); } class Customer { public $id; static $class = false; static function getInstance() { if(self::$class == false) { self::$class = new Customer; } else { return self::$class; } } public function set($id) { $this->id = $id; } public function get() { print $this->id; } } ?> I get the following error; Fatal error: Call to a member function set() on a non-object in ....../classes/customer.php on line 9 Can anyone tell me why I get this error? I know this code might look strange, but it's based on a component system that I'm writing for a CMS. The aim is to be able to replace HTML tags in the template e.g.; <!-- component:customer-login --> with; <?php component_customer_login(); ?> I also need to call pre-render methods of the "Customer" class to validate forms before output is made etc. If anyone can think of a better way, please let me know but in the first instance, I'd like to know why I get the "Fatal error" mentioned above. Cheers

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• Managing libraries and imports in a programming language

  - by sub

  I've created an interpreter for a stupid programming language in C++ and the whole core structure is finished (Tokenizer, Parser, Interpreter including Symbol tables, core functions, etc.). Now I have a problem with creating and managing the function libraries for this interpreter (I'll explain what I mean with that later) So currently my core function handler is horrible: // Simplified version myLangResult SystemFunction( name, argc, argv ) { if ( name == "print" ) { if( argc < 1 ) { Error('blah'); } cout << argv[ 0 ]; } else if ( name == "input" ) { if( argc < 1 ) { Error('blah'); } string res; getline( cin, res ); SetVariable( argv[ 0 ], res ); } else if ( name == "exit ) { exit( 0 ); } And now think of each else if being 10 times more complicated and there being 25 more system functions. Unmaintainable, feels horrible, is horrible. So I thought: How to create some sort of libraries that contain all the functions and if they are imported initialize themselves and add their functions to the symbol table of the running interpreter. However this is the point where I don't really know how to go on. What I wanted to achieve is that there is e.g.: an (extern?) string library for my language, e.g.: string, and it is imported from within a program in that language, example: import string myString = "abcde" print string.at( myString, 2 ) # output: c My problems: How to separate the function libs from the core interpreter and load them? How to get all their functions into a list and add it to the symbol table when needed? What I was thinking to do: At the start of the interpreter, as all libraries are compiled with it, every single function calls something like RegisterFunction( string namespace, myLangResult (*functionPtr) ); which adds itself to a list. When import X is then called from within the language, the list built with RegisterFunction is then added to the symbol table. Disadvantages that spring to mind: All libraries are directly in the interpreter core, size grows and it will definitely slow it down.

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• Routing redirection decision

  - by programming late night

  I have really no idea why I'm asking this as this a really completely irrelevant question for which I should have figured out an answer within milliseconds, yet I'm doing it. So in my project I have a Router class which splits up the request and selects the right page to be loaded. Fine so far. Now I have a page displayed when the user requests a page that doesn't exist, you know, 404. So theoretically, if the user entered mydomain.com/404 (I use mod_rewrite with a requests collector via index.php?req=*) the 404 error would be shown to him, but in fact there was no error - the 404 page would be displayed as a perfectly normal page. So if someone would try out requesting the 404 page via /404, he would be shown the page but he can't tell if the 404 page he requested doesn't exist and he is actually getting a, you guessed it, 404 error or if he actually found some flaw in the system that makes him able to see an error page when there is no error. I don't know how dumb this whole thing here is but I'm sure some of you have in fact ran into this problem already. Short version: If the user enters mydomain.com/404 the 404 page is shown even though there is no 404 error. I know this is a completely irrelevant question, please don't tell me, but I just spontaneously wanted to hear your thoughts on it. Strange eh? Should I redirect direct access to my 404-page to the home page? Should I do nothing? Should I just go to bed and stop asking irrelevant stuff?

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• Is Domain Anaemia appropriate in a Service Oriented Architecture?

  - by Stimul8d

  I want to be clear on this. When I say domain anaemia, I mean intentional domain anaemia, not accidental. In a world where most of our business logic is hidden away behind a bunch of services, is a full domain model really necessary? This is the question I've had to ask myself recently since working on a project where the "domain" model is in reality a persistence model; none of the domain objects contain any methods and this is a very intentional decision. Initially, I shuddered when I saw a library full of what are essentially type-safe data containers but after some thought it struck me that this particular system doesn't do much but basic CRUD operations, so maybe in this case this is a good choice. My problem I guess is that my experience so far has been very much focussed on a rich domain model so it threw me a little. The remainder of the domain logic is hidden away in a group of helpers, facades and factories which live in a separate assembly. I'm keen to hear what people's thoughts are on this. Obviously, the considerations for reuse of these classes are much simpler but is really that great a benefit?

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• How to use multiple identity numbers in one table?

  - by vincer

  I have an web application that creates printable forms, these forms have a unique number on them, the problem is I have 2 forms that separate numbers need to be created for them. ie) Form1- Numbered 2000000-2999999 Form2- Numbered 3000000-3999999 dbo.test2 - is my form information table Tsel - is my autoinc table for the 3000000 series numbers Tadv - is my autoinc table for the 2000000 series numbers What I have done is create 2 tables with just autoinc row (one for 2000000 series numbers and one for 3000000 series numbers), I then created a trigger to add a record to the coresponding table, read back the autoinc number and add it to my table that stores the form information including the just created autoinc number for the right series of forms. Although it does work, I'm concerned that the numbers will get messed up under load. I'm not sure the @@IDENTITY will always return the right value when many people are using the system. (I cannot have duplicates and I need to use the numbering form show above. See code below. ** TRIGGER ** CREATE TRIGGER MAKEANID2 ON dbo.test2 AFTER INSERT AS SET NOCOUNT ON declare @someid int declare @someid2 int declare @startfrom int declare @test1 varchar(10) select @someid=@@IDENTITY select @test1 = (Select name1 from test2 where sysid = @someid ) if @test1 = 'select' begin insert into Tsel Default values select @someid2 = @@IDENTITY end if @test1 = 'adv' begin insert into Tadv Default values select @someid2 = @@IDENTITY end update test2 set name2=(@someid2) where sysid = @someid SET NOCOUNT OFF

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• What do you call a generalized (non-GUI-related) "Model-View-Controller" architecture?

  - by dcuccia

  I am currently refactoring code that coordinates multiple hardware components for data acquisition, and feeling a bit like I'm recreating the wheel. In particular, an MVC-like pattern seems to be emerging. Except, this has nothing to do with a GUI and I'm worried that I'm forcing this particular pattern where another might be more appropriate. Here's my scenario: Individual hardware "component" classes obey interface contracts for each hardware type. Previously, component instances were orchestrated by a single monolithic InstrumentController class, which relied heavily on configuration + branching logic for executing a specific acquisition sequence. After an iteration, I have a separate controller for each component, with these controllers all managed by a small InstrumentControllerBase (or its derivatives). The composite system will receive "input" either programmatically or via inter-hardware component triggering - in either case these interactions are routed to, and handled by, the appropriate controller. So, I have something that feels MVC-esque, but I don't know if that's because I'm forcing the point. With little direct MVC experience in application development, it's hard to know if I'm just trying to make my scenario fit MVC, where another pattern might be a good alternative or complimentary. My problem is, search results and wiki documentation of these family of patterns seems to immediately drop me into GUI-specific discussions. I understand "M means Model data and the V means View" - but do you call the superset pattern? Component-Commander-Controller? Whence can I exhume examples exemplary?

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• Many tables for many users?

  - by Seagull

  I am new to web programming, so excuse the ignorance... ;-) I have a web application that in many ways can be considered to be a multi-tenant environment. By this I mean that each user of the application gets their own 'custom' environment, with absolutely no interaction between those users. So far I have built the web application as a 'single user' environment. In other words, I haven't actually done anything to support multi-users, but only worked on the functionality I want from the app. Here is my problem... What's the best way to build a multi-user environment: All users point to the same 'core' backend. In other words, I build the logic to separate users via appropriate SQL queries (eg. select * from table where user='123' and attribute='456'). Each user points to a unique tablespace, which is built separately as they join the system. In this case I would simply generate ALL the relevant SQL tables per user, with some sort of suffix for the user. (eg. now a query would look like 'select * from table_ where attribute ='456'). In short, it's a difference between "select * from table where USER=" and "select * from table_USER".

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• I never really understood: what is Application Binary Interface (ABI)?

  - by claws

  I never clearly understood what is an ABI. I'm sorry for such a lengthy question. I just want to clearly understand things. Please don't point me to wiki article, If could understand it, I wouldn't be here posting such a lengthy post. This is my mindset about different interfaces: TV remote is an interface between user and TV. It is an existing entity but useless (doesn't provide any functionality) by itself. All the functionality for each of those buttons on the remote is implemented in the Television set. Interface: It is a "existing entity" layer between the functionality and consumer of that functionality. An, interface by itself is doesn't do anything. It just invokes the functionality lying behind. Now depending on who the user is there are different type of interfaces. Command Line Interface(CLI) commands are the existing entities, consumer is the user and functionality lies behind. functionality: my software functionality which solves some purpose to which we are describing this interface. existing entities: commands consumer: user Graphical User Interface(GUI) window,buttons etc.. are the existing entities, again consumer is the user and functionality lies behind. functionality: my software functionality which solves some purpose to which we are describing this interface. existing entities: window,buttons etc.. consumer: user Application Programming Interface(API) functions or to be more correct, interfaces (in interfaced based programming) are the existing entities, consumer here is another program not a user. and again functionality lies behind this layer. functionality: my software functionality which solves some purpose to which we are describing this interface. existing entities: functions, Interfaces(array of functions). consumer: another program/application. Application Binary Interface (ABI) Here is my problem starts. functionality: ??? existing entities: ??? consumer: ??? I've wrote few softwares in different languages and provided different kind of interfaces (CLI, GUI, API) but I'm not sure, if I ever, provided any ABI. http://en.wikipedia.org/wiki/Application_binary_interface says: ABIs cover details such as data type, size, and alignment; the calling convention, which controls how functions' arguments are passed and return values retrieved; the system call numbers and how an application should make system calls to the operating system; Other ABIs standardize details such as the C++ name mangling,[2] . exception propagation,[3] and calling convention between compilers on the same platform, but do not require cross-platform compatibility. Who needs these details? Please don't say, OS. I know assembly programming. I know how linking & loading works. I know what exactly happens inside. Where did C++ name mangling come in between? I thought we are talking at the binary level. Where did languages come in between? anyway, I've downloaded the [PDF] System V Application Binary Interface Edition 4.1 (1997-03-18) to see what exactly it contains. Well, most of it didn't make any sense. Why does it contain 2 chapters (4th & 5th) which describe the ELF file format.Infact, these are the only 2 significant chapters that specification. Rest of all the chapters "Processor Specific". Anyway, I thought that it is completely different topic. Please don't say that ELF file format specs are the ABI. It doesn't qualify to be Interface according to the definition. I know, since we are talking at such low level it must be very specific. But I'm not sure how is it "Instruction Set Architecture(ISA)" specific? Where can I find MS Window's ABI? So, these are the major queries that are bugging me.

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• MSSQL Server using multiple ID Numbers

  - by vincer

  I have an web application that creates printable forms, these forms have a unique number on them, the problem is I have 2 forms that separate numbers need to be created for them. ie) Form1- Numbered 2000000-2999999 Form2- Numbered 3000000-3999999 dbo.test2 - is my form information table Tsel - is my autoinc table for the 3000000 series numbers Tadv - is my autoinc table for the 2000000 series numbers What I have done is create 2 tables with just autoinc row (one for 2000000 series numbers and one for 3000000 series numbers), I then created a trigger to add a record to the coresponding table, read back the autoinc number and add it to my table that stores the form information including the just created autoinc number for the right series of forms. Although it does work, I'm concerned that the numbers will get messed up under load. I'm not sure the @@IDENTITY will always return the right value when many people are using the system. (I cannot have duplicates and I need to use the numbering form show above. Thanks for any help See code below. ** TRIGGER ** CREATE TRIGGER MAKEANID2 ON dbo.test2 AFTER INSERT AS SET NOCOUNT ON declare @someid int declare @someid2 int declare @startfrom int declare @test1 varchar(10) select @someid=@@IDENTITY select @test1 = (Select name1 from test2 where sysid = @someid ) if @test1 = 'select' begin insert into Tsel Default values select @someid2 = @@IDENTITY end if @test1 = 'adv' begin insert into Tadv Default values select @someid2 = @@IDENTITY end update test2 set name2=(@someid2) where sysid = @someid SET NOCOUNT OFF

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• How to increase my "advanced" knowledge of PHP further? (quickly)

  - by Kerry

  I have been working with PHP for years and gotten a very good grasp of the language, created many advanced and not-so-advanced systems that are working very well. The problem I'm running into is that I only learn when I find a need for something that I haven't learned before. This causes me to look up solutions and other code that handles the problem, and so I will learn about a new function or structure that I hadn't seen before. It is in this way that I have learned many of my better techniques (such as studying classes put out by Amazon, Google or other major companies). The main problem with this is the concept of not being able to learn something if you don't know it exists. For instance, it took me several months of programming to learn about the empty() function, and I simply would check the string length using strlen() to check for empty values. I'm now getting into building bigger and bigger systems, and I've started to read blogs like highscalability.com and been researching MySQL replication and server data for scaling. I know that structure of your code is very important to make full systems work. After reading a recent blog about reddit's structure, it made me question if there is some standard or "accepted systems" out there. I have looked into frameworks (I've used Kohana, which I regretted, but decided that PHP frameworks were not for me) and I prefer my own library of functions rather than having a framework. My current structure is a mix between WordPress, Kohana and my own knowledge. The ways I can see as being potentially beneficial are: Read blogs Read tutorials Work with someone else Read a book What would be the best way(s) to "get to the next level" the level of being a very good system developer?

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• Applying ServiceKnownTypeAttribute to WCF service with Spring

  - by avidgoffer

  I am trying to apply the ServiceKnownTypeAttribute to my WCF Service but keep getting the error below my config. Does anyone have any ideas? <object id="HHGEstimating" type="Spring.ServiceModel.ServiceExporter, Spring.Services"> <property name="TargetName" value="HHGEstimatingHelper"/> <property name="Name" value="HHGEstimating"/> <property name="Namespace" value="http://www.igcsoftware.com/HHGEstimating"/> <property name="TypeAttributes"> <list> <ref local="wcfErrorBehavior"/> <ref local="wcfSilverlightFaultBehavior"/> <object type="System.ServiceModel.ServiceKnownTypeAttribute, System.ServiceModel"> <constructor-arg name="type" value="IGCSoftware.HHG.Business.UserControl.AtlasUser, IGCSoftware.HHG.Business"/> </object> </list> </property> Error thrown by a dependency of object 'HHGEstimating' defined in 'assembly [IGCSoftware.HHG.WebService, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null], resource [IGCSoftware.HHG.WebService.Resources.Spring.objects.xml] line 46' : '1' constructor arguments specified but no matching constructor found in object 'System.ServiceModel.ServiceKnownTypeAttribute#25A5628' (hint: specify argument indexes, names, or types to avoid ambiguities). while resolving 'TypeAttributes[2]' to 'System.ServiceModel.ServiceKnownTypeAttribute#25A5628' defined in 'assembly [IGCSoftware.HHG.WebService, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null], resource [IGCSoftware.HHG.WebService.Resources.Spring.objects.xml] line 46' Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: Spring.Objects.Factory.ObjectCreationException: Error thrown by a dependency of object 'HHGEstimating' defined in 'assembly [IGCSoftware.HHG.WebService, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null], resource [IGCSoftware.HHG.WebService.Resources.Spring.objects.xml] line 46' : '1' constructor arguments specified but no matching constructor found in object 'System.ServiceModel.ServiceKnownTypeAttribute#25A5628' (hint: specify argument indexes, names, or types to avoid ambiguities). while resolving 'TypeAttributes[2]' to 'System.ServiceModel.ServiceKnownTypeAttribute#25A5628' defined in 'assembly [IGCSoftware.HHG.WebService, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null], resource [IGCSoftware.HHG.WebService.Resources.Spring.objects.xml] line 46' Source Error: An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below. Stack Trace: [ObjectCreationException: Error thrown by a dependency of object 'HHGEstimating' defined in 'assembly [IGCSoftware.HHG.WebService, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null], resource [IGCSoftware.HHG.WebService.Resources.Spring.objects.xml] line 46' : '1' constructor arguments specified but no matching constructor found in object 'System.ServiceModel.ServiceKnownTypeAttribute#25A5628' (hint: specify argument indexes, names, or types to avoid ambiguities). while resolving 'TypeAttributes[2]' to 'System.ServiceModel.ServiceKnownTypeAttribute#25A5628' defined in 'assembly [IGCSoftware.HHG.WebService, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null], resource [IGCSoftware.HHG.WebService.Resources.Spring.objects.xml] line 46'] Spring.Objects.Factory.Support.ObjectDefinitionValueResolver.ResolveInnerObjectDefinition(String name, String innerObjectName, String argumentName, IObjectDefinition definition, Boolean singletonOwner) in l:\projects\spring-net\trunk\src\Spring\Spring.Core\Objects\Factory\Support\ObjectDefinitionValueResolver.cs:300 Spring.Objects.Factory.Support.ObjectDefinitionValueResolver.ResolvePropertyValue(String name, IObjectDefinition definition, String argumentName, Object argumentValue) in l:\projects\spring-net\trunk\src\Spring\Spring.Core\Objects\Factory\Support\ObjectDefinitionValueResolver.cs:150 Spring.Objects.Factory.Support.ObjectDefinitionValueResolver.ResolveValueIfNecessary(String name, IObjectDefinition definition, String argumentName, Object argumentValue) in l:\projects\spring-net\trunk\src\Spring\Spring.Core\Objects\Factory\Support\ObjectDefinitionValueResolver.cs:112 Spring.Objects.Factory.Config.ManagedList.Resolve(String objectName, IObjectDefinition definition, String propertyName, ManagedCollectionElementResolver resolver) in l:\projects\spring-net\trunk\src\Spring\Spring.Core\Objects\Factory\Config\ManagedList.cs:126 Spring.Objects.Factory.Support.ObjectDefinitionValueResolver.ResolvePropertyValue(String name, IObjectDefinition definition, String argumentName, Object argumentValue) in l:\projects\spring-net\trunk\src\Spring\Spring.Core\Objects\Factory\Support\ObjectDefinitionValueResolver.cs:201 Spring.Objects.Factory.Support.ObjectDefinitionValueResolver.ResolveValueIfNecessary(String name, IObjectDefinition definition, String argumentName, Object argumentValue) in l:\projects\spring-net\trunk\src\Spring\Spring.Core\Objects\Factory\Support\ObjectDefinitionValueResolver.cs:112 Spring.Objects.Factory.Support.AbstractAutowireCapableObjectFactory.ApplyPropertyValues(String name, RootObjectDefinition definition, IObjectWrapper wrapper, IPropertyValues properties) in l:\projects\spring-net\trunk\src\Spring\Spring.Core\Objects\Factory\Support\AbstractAutowireCapableObjectFactory.cs:373 Spring.Objects.Factory.Support.AbstractAutowireCapableObjectFactory.PopulateObject(String name, RootObjectDefinition definition, IObjectWrapper wrapper) in l:\projects\spring-net\trunk\src\Spring\Spring.Core\Objects\Factory\Support\AbstractAutowireCapableObjectFactory.cs:563 Spring.Objects.Factory.Support.AbstractAutowireCapableObjectFactory.ConfigureObject(String name, RootObjectDefinition definition, IObjectWrapper wrapper) in l:\projects\spring-net\trunk\src\Spring\Spring.Core\Objects\Factory\Support\AbstractAutowireCapableObjectFactory.cs:1844 Spring.Objects.Factory.Support.AbstractAutowireCapableObjectFactory.InstantiateObject(String name, RootObjectDefinition definition, Object[] arguments, Boolean allowEagerCaching, Boolean suppressConfigure) in l:\projects\spring-net\trunk\src\Spring\Spring.Core\Objects\Factory\Support\AbstractAutowireCapableObjectFactory.cs:918 Spring.Objects.Factory.Support.AbstractObjectFactory.CreateAndCacheSingletonInstance(String objectName, RootObjectDefinition objectDefinition, Object[] arguments) in l:\projects\spring-net\trunk\src\Spring\Spring.Core\Objects\Factory\Support\AbstractObjectFactory.cs:2120 Spring.Objects.Factory.Support.AbstractObjectFactory.GetObjectInternal(String name, Type requiredType, Object[] arguments, Boolean suppressConfigure) in l:\projects\spring-net\trunk\src\Spring\Spring.Core\Objects\Factory\Support\AbstractObjectFactory.cs:2046 Spring.Objects.Factory.Support.DefaultListableObjectFactory.PreInstantiateSingletons() in l:\projects\spring-net\trunk\src\Spring\Spring.Core\Objects\Factory\Support\DefaultListableObjectFactory.cs:505 Spring.Context.Support.AbstractApplicationContext.Refresh() in l:\projects\spring-net\trunk\src\Spring\Spring.Core\Context\Support\AbstractApplicationContext.cs:911 _dynamic_Spring.Context.Support.XmlApplicationContext..ctor(Object[] ) +197 Spring.Reflection.Dynamic.SafeConstructor.Invoke(Object[] arguments) in l:\projects\spring-net\trunk\src\Spring\Spring.Core\Reflection\Dynamic\DynamicConstructor.cs:116 Spring.Context.Support.RootContextInstantiator.InvokeContextConstructor(ConstructorInfo ctor) in l:\projects\spring-net\trunk\src\Spring\Spring.Core\Context\Support\ContextHandler.cs:550 Spring.Context.Support.ContextInstantiator.InstantiateContext() in l:\projects\spring-net\trunk\src\Spring\Spring.Core\Context\Support\ContextHandler.cs:494 Spring.Context.Support.ContextHandler.InstantiateContext(IApplicationContext parentContext, Object configContext, String contextName, Type contextType, Boolean caseSensitive, String[] resources) in l:\projects\spring-net\trunk\src\Spring\Spring.Core\Context\Support\ContextHandler.cs:330 Spring.Context.Support.ContextHandler.Create(Object parent, Object configContext, XmlNode section) in l:\projects\spring-net\trunk\src\Spring\Spring.Core\Context\Support\ContextHandler.cs:280 [ConfigurationErrorsException: Error creating context 'spring.root': Error thrown by a dependency of object 'HHGEstimating' defined in 'assembly [IGCSoftware.HHG.WebService, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null], resource [IGCSoftware.HHG.WebService.Resources.Spring.objects.xml] line 46' : '1' constructor arguments specified but no matching constructor found in object 'System.ServiceModel.ServiceKnownTypeAttribute#25A5628' (hint: specify argument indexes, names, or types to avoid ambiguities). while resolving 'TypeAttributes[2]' to 'System.ServiceModel.ServiceKnownTypeAttribute#25A5628' defined in 'assembly [IGCSoftware.HHG.WebService, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null], resource [IGCSoftware.HHG.WebService.Resources.Spring.objects.xml] line 46'] System.Configuration.BaseConfigurationRecord.EvaluateOne(String[] keys, SectionInput input, Boolean isTrusted, FactoryRecord factoryRecord, SectionRecord sectionRecord, Object parentResult) +202 System.Configuration.BaseConfigurationRecord.Evaluate(FactoryRecord factoryRecord, SectionRecord sectionRecord, Object parentResult, Boolean getLkg, Boolean getRuntimeObject, Object& result, Object& resultRuntimeObject) +1061 System.Configuration.BaseConfigurationRecord.GetSectionRecursive(String configKey, Boolean getLkg, Boolean checkPermission, Boolean getRuntimeObject, Boolean requestIsHere, Object& result, Object& resultRuntimeObject) +1431 System.Configuration.BaseConfigurationRecord.GetSection(String configKey, Boolean getLkg, Boolean checkPermission) +56 System.Configuration.BaseConfigurationRecord.GetSection(String configKey) +8 System.Web.Configuration.HttpConfigurationSystem.GetApplicationSection(String sectionName) +45 System.Web.Configuration.HttpConfigurationSystem.GetSection(String sectionName) +49 System.Web.Configuration.HttpConfigurationSystem.System.Configuration.Internal.IInternalConfigSystem.GetSection(String configKey) +6 System.Configuration.ConfigurationManager.GetSection(String sectionName) +78 Spring.Util.ConfigurationUtils.GetSection(String sectionName) in l:\projects\spring-net\trunk\src\Spring\Spring.Core\Util\ConfigurationUtils.cs:69 Spring.Context.Support.ContextRegistry.InitializeContextIfNeeded() in l:\projects\spring-net\trunk\src\Spring\Spring.Core\Context\Support\ContextRegistry.cs:340 Spring.Context.Support.ContextRegistry.GetContext() in l:\projects\spring-net\trunk\src\Spring\Spring.Core\Context\Support\ContextRegistry.cs:206 Spring.ServiceModel.Activation.ServiceHostFactory.CreateServiceHost(String reference, Uri[] baseAddresses) in l:\projects\spring-net\trunk\src\Spring\Spring.Services\ServiceModel\Activation\ServiceHostFactory.cs:66 System.ServiceModel.HostingManager.CreateService(String normalizedVirtualPath) +11687036 System.ServiceModel.HostingManager.ActivateService(String normalizedVirtualPath) +42 System.ServiceModel.HostingManager.EnsureServiceAvailable(String normalizedVirtualPath) +479 [ServiceActivationException: The service '/HHGEstimating.svc' cannot be activated due to an exception during compilation. The exception message is: Error creating context 'spring.root': Error thrown by a dependency of object 'HHGEstimating' defined in 'assembly [IGCSoftware.HHG.WebService, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null], resource [IGCSoftware.HHG.WebService.Resources.Spring.objects.xml] line 46' : '1' constructor arguments specified but no matching constructor found in object 'System.ServiceModel.ServiceKnownTypeAttribute#25A5628' (hint: specify argument indexes, names, or types to avoid ambiguities). while resolving 'TypeAttributes[2]' to 'System.ServiceModel.ServiceKnownTypeAttribute#25A5628' defined in 'assembly [IGCSoftware.HHG.WebService, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null], resource [IGCSoftware.HHG.WebService.Resources.Spring.objects.xml] line 46'.] System.ServiceModel.AsyncResult.End(IAsyncResult result) +11592858 System.ServiceModel.Activation.HostedHttpRequestAsyncResult.End(IAsyncResult result) +194 System.ServiceModel.Activation.HostedHttpRequestAsyncResult.ExecuteSynchronous(HttpApplication context, Boolean flowContext) +176 System.ServiceModel.Activation.HttpModule.ProcessRequest(Object sender, EventArgs e) +275 System.Web.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +68 System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +75

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• The null value cannot be assigned to a member with type System.Int64 which is a non-nullable value t

  - by BritishDeveloper

  I'm getting the following error in my MVC2 app using Linq to SQL (I am new to both). I am connected to an actual SQL server not weird mdf: System.InvalidOperationException The null value cannot be assigned to a member with type System.Int64 which is a non-nullable value type My SQL table has a column called MessageID. It is BigInt type and has a primary key, NOT NULL and an IDENTITY 1 1, no Default In my dbml designer it has the following declaration for this field: [global::System.Data.Linq.Mapping.ColumnAttribute(Storage="_MessageId", AutoSync=AutoSync.OnInsert, DbType="BigInt NOT NULL IDENTITY", IsPrimaryKey=true, IsDbGenerated=true)] public long MessageId { get { return this._MessageId; } set { if ((this._MessageId != value)) { this.OnMessageIdChanging(value); this.SendPropertyChanging(); this._MessageId = value; this.SendPropertyChanged("MessageId"); this.OnMessageIdChanged(); } } } It keeps telling me that null cannot be assigned - I'm not passing through null! It's a long - it can't even be null! Am I doing something stupid? I can't find a solution anywhere! I made this work by changing the type of this property to Nullable<long> but surely this can't be right? Update: I am using InsertOnSubmit. Simplified code: public ActionResult Create(Message message) { if (ModelState.IsValid) { var db = new MessagingDataContext(); db.Messages.InsertOnSubmit(message); db.SubmitChanges(); //line 93 (where it breaks) } } breaks on SubmitChanges() with the error at the top of this question. Update2: Stack trace: at Read_Object(ObjectMaterializer`1 ) at System.Data.Linq.SqlClient.ObjectReaderCompiler.ObjectReader`2.MoveNext() at System.Linq.Enumerable.FirstOrDefault[TSource](IEnumerable`1 source) at System.Data.Linq.ChangeDirector.StandardChangeDirector.DynamicInsert(TrackedObject item) at System.Data.Linq.ChangeDirector.StandardChangeDirector.Insert(TrackedObject item) at System.Data.Linq.ChangeProcessor.SubmitChanges(ConflictMode failureMode) at System.Data.Linq.DataContext.SubmitChanges(ConflictMode failureMode) at Qanda.Controllers.MessagingController.Ask(Message message) in C:\Qanda\Qanda\Controllers\MessagingController.cs:line 93 Update3: No one knows and I don't have enough clout to offer a bounty! So continued on my ASP.NET blog. Please help!

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• Java, server client TCP communication ends with RST

  - by Senne

  I'm trying to figure out if this is normal. Because without errors, a connection should be terminated by: FIN -> <- ACK <- FIN ACK -> I get this at the end of a TCP connection (over SSL, but i also get it with non-encrypted): From To 1494 server client TCP search-agent > 59185 [PSH, ACK] Seq=25974 Ack=49460 Win=63784 Len=50 1495 client server TCP 59185 > search-agent [ACK] Seq=49460 Ack=26024 Win=63565 Len=0 1496 client server TCP 59185 > search-agent [PSH, ACK] Seq=49460 Ack=26024 Win=63565 Len=23 1497 client server TCP 59185 > search-agent [FIN, ACK] Seq=49483 Ack=26024 Win=63565 Len=0 1498 server client TCP search-agent > 59185 [PSH, ACK] Seq=26024 Ack=49484 Win=63784 Len=23 1499 client server TCP 59185 > search-agent [RST, ACK] Seq=49484 Ack=26047 Win=0 Len=0 The client exits normally and reaches socket.close, shouldn't then the connection be shut down normally, without a reset? I can't find anything about the TCP streams of java on google... Here is my code: Server: package Security; import java.io.*; import java.net.*; import javax.net.ServerSocketFactory; import javax.net.ssl.*; import java.util.*; public class SSLDemoServer { private static ServerSocket serverSocket; private static final int PORT = 1234; public static void main(String[] args) throws IOException { int received = 0; String returned; ObjectInputStream input = null; PrintWriter output = null; Socket client; System.setProperty("javax.net.ssl.keyStore", "key.keystore"); System.setProperty("javax.net.ssl.keyStorePassword", "vwpolo"); System.setProperty("javax.net.ssl.trustStore", "key.keystore"); System.setProperty("javax.net.ssl.trustStorePassword", "vwpolo"); try { System.out.println("Trying to set up server ..."); ServerSocketFactory factory = SSLServerSocketFactory.getDefault(); serverSocket = factory.createServerSocket(PORT); System.out.println("Server started!\n"); } catch (IOException ioEx) { System.out.println("Unable to set up port!"); ioEx.printStackTrace(); System.exit(1); } while(true) { client = serverSocket.accept(); System.out.println("Client trying to connect..."); try { System.out.println("Trying to create inputstream..."); input = new ObjectInputStream(client.getInputStream()); System.out.println("Trying to create outputstream..."); output = new PrintWriter(client.getOutputStream(), true); System.out.println("Client successfully connected!"); while( true ) { received = input.readInt(); returned = Integer.toHexString(received); System.out.print(" " + received); output.println(returned.toUpperCase()); } } catch(SSLException sslEx) { System.out.println("Connection failed! (non-SSL connection?)\n"); client.close(); continue; } catch(EOFException eofEx) { System.out.println("\nEnd of client data.\n"); } catch(IOException ioEx) { System.out.println("I/O problem! (correct inputstream?)"); } try { input.close(); output.close(); } catch (Exception e) { } client.close(); System.out.println("Client closed.\n"); } } } Client: package Security; import java.io.*; import java.net.*; import javax.net.ssl.*; import java.util.*; public class SSLDemoClient { private static InetAddress host; private static final int PORT = 1234; public static void main(String[] args) { System.setProperty("javax.net.ssl.keyStore", "key.keystore"); System.setProperty("javax.net.ssl.keyStorePassword", "vwpolo"); System.setProperty("javax.net.ssl.trustStore", "key.keystore"); System.setProperty("javax.net.ssl.trustStorePassword", "vwpolo"); System.out.println("\nCreating SSL socket ..."); SSLSocket socket = null; try { host = InetAddress.getByName("192.168.56.101"); SSLSocketFactory factory = (SSLSocketFactory) SSLSocketFactory.getDefault(); socket = (SSLSocket) factory.createSocket(host, PORT); socket.startHandshake(); } catch(UnknownHostException uhEx) { System.out.println("\nHost ID not found!\n"); System.exit(1); } catch(SSLException sslEx) { System.out.println("\nHandshaking unsuccessful ..."); System.exit(1); } catch (IOException e) { e.printStackTrace(); } System.out.println("\nHandshaking succeeded ...\n"); SSLClientThread client = new SSLClientThread(socket); SSLReceiverThread receiver = new SSLReceiverThread(socket); client.start(); receiver.start(); try { client.join(); receiver.join(); System.out.println("Trying to close..."); socket.close(); } catch(InterruptedException iEx) { iEx.printStackTrace(); } catch(IOException ioEx) { ioEx.printStackTrace(); } System.out.println("\nClient finished."); } } class SSLClientThread extends Thread { private SSLSocket socket; public SSLClientThread(SSLSocket s) { socket = s; } public void run() { try { ObjectOutputStream output = new ObjectOutputStream(socket.getOutputStream()); for( int i = 1; i < 1025; i++) { output.writeInt(i); sleep(10); output.flush(); } output.flush(); sleep(1000); output.close(); } catch(IOException ioEx) { System.out.println("Socket closed or unable to open socket."); } catch(InterruptedException iEx) { iEx.printStackTrace(); } } } class SSLReceiverThread extends Thread { private SSLSocket socket; public SSLReceiverThread(SSLSocket s) { socket = s; } public void run() { String response = null; BufferedReader input = null; try { input = new BufferedReader( new InputStreamReader(socket.getInputStream())); try { response = input.readLine(); while(!response.equals(null)) { System.out.print(response + " "); response = input.readLine(); } } catch(Exception e) { System.out.println("\nEnd of server data.\n"); } input.close(); } catch(IOException ioEx) { ioEx.printStackTrace(); } } }

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• Using MongoDB with Ruby On Rails and the Mongomapper plugin

  - by Micke

  Hello, i am currently trying to learn Ruby On Rails as i am a long-time PHP developer so i am building my own community like page. I have came pritty far and have made the user models and suchs using MySQL. But then i heard of MongoDB and looked in to it a little bit more and i find it kinda nice. So i have set it up and i am using mongomapper for the connection between rails and MongoDB. And i am now using it for the News page on the site. I also have a profile page for every User which includes their own guestbook so other users can come to their profile and write a little message to them. My thought now is to change the User models from using MySQL to start using MongoDB. I can start by showing how the models for each User is set up. The user model: class User < ActiveRecord::Base has_one :guestbook, :class_name => "User::Guestbook" The Guestbook model model: class User::Guestbook < ActiveRecord::Base belongs_to :user has_many :posts, :class_name => "User::Guestbook::Posts", :foreign_key => "user_id" And then the Guestbook posts model: class User::Guestbook::Posts < ActiveRecord::Base belongs_to :guestbook, :class_name => "User::Guestbook" I have divided it like this for my own convenience but now when i am going to try to migrate to MongoDB i dont know how to make the tables. I would like to have one table for each user and in that table a "column" for all the guestbook entries since MongoDB can have a EmbeddedDocument. I would like to do this so i just have one Table for each user and not like now when i have three tables just to be able to have a guestbook. So my thought is to have it like this: The user model: class User include MongoMapper::Document one :guestbook, :class_name => "User::Guestbook" The Guestbook model model: class User::Guestbook include MongoMapper::EmbeddedDocument belongs_to :user many :posts, :class_name => "User::Guestbook::Posts", :foreign_key => "user_id" And then the Guestbook posts model: class User::Guestbook::Posts include MongoMapper::EmbeddedDocument belongs_to :guestbook, :class_name => "User::Guestbook" But then i can think of one problem.. That when i just want to fetch the user information like a nickname and a birthdate then it will have to fetch all the users guestbook posts. And if each user has like a thousand posts in the guestbook it will get really much to fetch for the system. Or am i wrong? Do you think i should do it any other way? Thanks in advance and sorry if i am hard to understand but i am not so educated in the english language :)

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