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• Help needed implementing a web based file management system with a file hierarchy system, help neede

  - by molleman

  Hello i am trying to create a web application that will allow users to upload files online, i am using gwt while using hibernate for database communication, i am able to upload file to a server , and store them on the server. but what i want is to associate the files with a user. i want the user to be able to create folders and store a file in sub folders. my logic was to use the composite pattern to store folders and fileLocations with a user but i am am finding it difficult to implement this so i can show the files and folders within a gwt tree. what would be the best way to implement a hierarchy of folders and information of the location of a file so it could be displayed in a gwt tree? what i did have was a User would hold a reference to a root folder and then each sub folder could hold folders or fileLocations. i used the composite pattern to implement the file hierarchy, but when i want to display a the contents of a folder i need a for loop for each list. so i could a folder within a folder within a folder that would need 3 for loops to show the contents of my folders. What is the best way to implement this file management system. so what do you guys think?

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• Load Balance WCF and Share a Remote MSMQ for High Throughput

  - by BarDev

  After a ton of reading in books and on the web, I have noticed hints of information that WCF and MSMQ can be used in achieving high throughput. The information I have seen mentions using multiple WCF services in a farm that reads from a single MSMQ queue. The problem is that I have found paragraphs here and there that mentions that high throughput can be done, but I cannot seem to find a document of how to implement it. The following is an excerpt from a MSDN article. The following paragraph is from Best Practices for Queued Communication http://msdn.microsoft.com/en-us/library/ms731093.aspx To achieve higher throughput and availability, use a farm of WCF services that read from the queue. This requires that all of these services expose the same contract on the same endpoint. The farm approach works best for applications that have high production rates of messages because it enables a number of services to all read from the same queue. This is what I'm trying to solve. I have an intranet application where a client sends a request to a WCF service. But I want the ability to load balance the WCF services on multiple servers in a farm. I also want these WCF services in the farm to do transactional reads from a remote MSMQ when an item is available in the Queue. If this is possible, an issue I have is that I do not understand the activation process of WCF to retrieve messages from a remote queue. If this is possible, does anyone know of any articles or Webcasts that would explain it in detail? BarDev

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• NHibernate Generators

  - by Dan

  What is the best tool for generating Entity Class and/or hbm files and/or sql script for NHibernate. This list below is from http://www.hibernate.org/365.html, which is the best any why? Moregen Free, Open Source (GPL) O/R Generator that can merge into existing Visual Studio Projects. Also merges changes to generated classes. NConstruct Lite Free tool for generating NHibernate O/R mapping source code. Different databases support (Microsoft SQL Server, Oracle, Access). GENNIT NHibernate Code Generator Free/Commercial Web 2.0 code generation of NHibernate code using WYSIWYG online UML designer. GenWise Studio with NHibernate Template Commercial product; Imports your existing database and generates all XML and Classes, including factories. It can also generate a asp.net web-application for your NHibernate BO-Layer automatically. HQL Analyzer and hbm.xml GUI Editor ObjectMapper by Mats Helander is a mapping GUI with NHibernate support MyGeneration is a template-based code generator GUI. Its template library includes templates for generating mapping files and classes from a database. AndroMDA is an open-source code generation framework that uses Model Driven Architecture (MDA) to transform UML models into deployable components. It supports generation of data access layers that use NHibernate as their persistence framework. CodeSmith Template for NH NHibernate Helper Kit is a VS2005 add-in to generate classes and mapping files. NConstruct - Intelligent Software Factory Commercial product; Full .NET C# source code generation for all tiers of the information system trough simple wizard procedure. O/R mapping based on NHibernate. For both WinForms and ASP.NET 2.0.

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• Server Security

  - by mahatmanich

  I want to run my own root server (directly accessible from the web without a hardware firewall) with debian lenny, apache2, php5, mysql, postfix MTA, sftp (based on ssh) and maybe dns server. What measures/software would you recomend, and why, to secure this server down and minimalize the attack vector? Webapplications aside ... This is what I have so far: iptables (for gen. packet filtering) fail2ban (brute force attack defense) ssh (chang default, port disable root access) modsecurity - is really clumsy and a pain (any alternative here?) ?Sudo why should I use it? what is the advantage to normal user handling thinking about greensql for mysql www.greensql.net is tripwire worth looking at? snort? What am I missing? What is hot and what is not? Best practices? I like "KISS" - Keep it simple secure, I know it would be nice! Thanks in advance ...

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• WMD markdown editor - HTML to Markdown conversion

  - by gg1

  I am using wmd markdown editor on a project and had a question: When I post the form containing the markdown text area, it (as expected) posts html to the server. However, say upon server-side validation something fails and I need to send the user back to edit their entry, is there anyway to refill the textarea with just the markdown and not the html? Since as I have it set up, the server only has access to the post data (which is in the form of html) so I can't seem to think of a way to do this. Any ideas? Preferably a non-javascript based solution. Update: I found an html to markdown converter called markdownify. I guess this might be the best solution for displaying the markdown back to the user...any better alternatives are welcome! Update 2: I found this post on SO and I guess there is an option to send the data to the server as markdown instead of html. Are there any downsides to simply storing the data as markdown in the database? What about displaying it back to the user (outside of an editor)? Maybe it would be best to post both versions (html AND markdown) to the server... SOLVED: I can simply use php markdown to convert the markdown to html serverside.

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• WPF Usercontrol interaction with parent view / viewmodel

  - by obaylis

  Hi I have a mainView window which has its dataContext set to it's own viewModel. On that viewModel is a DateTime property which in turn is bound to a datepicker on my main view using 2 way binding. <toolkit:DatePicker DateSelected="{Binding mainDateTimeProperty, Mode=TwoWay}" /> This is all fine so far. On the change of my datetime property I create a list which is then bound to a datagrid elsewhere on the mainview. This all works fine. My question is to do with a usercontrol I want to add to the main view. I want this usercontrol to be self contained so have created it with it's own viewmodel but it does also need access to mainDateTimeProperty I thought that best way to go would be to create a dependencyProperty on the usercontrol and when I create my control in the main view I bind the dp to the datetime as follows. <uc:MyNewUserControl DateProperty="{Binding mainDateTimeProperty}" /> Trouble is how do I have the usercontrol maintain datacontext with it's viewmodel and yet still have the dependency property bound to a property on the main view model? Hope this is clear. Can post some more code if necessary. Looking for a best practice approach if possible. Thanks very much for any advice.

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• VS Solution and Mercurial repository layout for a c# project with plugins and external libraries.

  - by Joviee

  I'm developing a project in .NET (using C# to be more specific). Using Visual Studio as an IDE. Using Mercurial for version control. I'll be using some third-party libraries: ThirdParty.Foo.dll ThirdParty.Bar.dll ThirdParty.Baz.dll And some in-house libraries: Company.A Company.B Company.C Company.D (References third party libraries) Company.E (References Company.A) The project itself will have the following components: Project.Core Project.DataModel (references in-house/third-party libraries) Project.GUI (references Core, DataModel, and in-house/third-party libraries) Project.PluginOne (references Core, DataModel, and in-house/third-party libraries) Project.PluginTwo (references Core, DataModel, and in-house/third-party libraries) * can be an arbitrary number of plugins * I'm quite new to Mercurial, so I don't really know the best way to structure my repositories for a project like this, with a lot of interconnected components. The in-house libraries are fairly distinct, so I would say that each one of them should have its own repository. However, some of them use functionality provided by others. How should these dependencies be managed? The project plug-ins should be distinct from eachother, so I'd imagine that each would have its own repository. How should the dependencies on the in-house/third-party libraries and the rest of the project (Project.DataModel and Project.Core) be managed, with regards to the solution layout and the repository layout? So basically, for a project like this, what are the best way of structuring: (a) my visual studio solutions (b) my source control repository/repositories

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• Unity The parameter host could not be resolved when attempting to call constructor

  - by Terrance

  When I attempt to instantiate my instance of the base class I get the error: a ResolutionFailedException with roughly the following error "The parameter host could not be resolved when attempting to call constructor" I'm currently not using an Interface for the base type and my instance of the class is inheriting the base type class. I'm new to Unity and DI so I'm thinking its something I forgot possibly. ExeConfigurationFileMap map = new ExeConfigurationFileMap(); map.ExeConfigFilename = "Unity.Config"; Configuration config = ConfigurationManager.OpenMappedExeConfiguration(map, ConfigurationUserLevel.None); UnityConfigurationSection section = (UnityConfigurationSection)config.GetSection("unity"); IUnityContainer container = new UnityContainer(); section.Containers.Default.Configure(container); //Throws exception here on this BaseCalculatorServer server = container.Resolve<BaseCalculatorServer>(); and the Unity.Config file <container> <types> <type name ="CalculatorServer" type="Calculator.Logic.BaseCalculatorServer, Calculator.Logic" mapTo="Calculator.Logic.CalculateApi, Calculator.Logic"/> </types> </container> </containers> The Base class using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Runtime.Serialization; using System.ServiceModel; using System.ServiceModel.Transactions; using Microsoft.Practices.Unity; using Calculator.Logic; namespace Calculator.Logic { public class BaseCalculatorServer : IDisposable { public BaseCalculatorServer(){} public CalculateDelegate Calculate { get; set; } public CalculationHistoryDelegate CalculationHistory { get; set; } /// <summary> /// Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources. /// </summary> public void Dispose() { this.Dispose(); } } } The Implementation using System; using System.Collections.Generic; using System.Linq; using System.Text; using Calculator.Logic; using System.ServiceModel; using System.ServiceModel.Configuration; using Microsoft.Practices.Unity; namespace Calculator.Logic { public class CalculateApi:BaseCalculatorServer { public CalculateApi(ServiceHost host) { host.Open(); Console.WriteLine("Press Enter To Exit"); Console.ReadLine(); host.Close(); } public CalculateDelegate Calculate { get; set; } public CalculationHistoryDelegate CalculationHistory { get; set; } } } Yes both base class and implementation are in the same Namespace and thats something design wise that will change once I get this working. Oh and a more detailed error Resolution of the dependency failed, type = "Calculator.Logic.BaseCalculatorServer", name = "". Exception message is: The current build operation (build key Build Key[Calculator.Logic.BaseCalculatorServer, null]) failed: The value for the property "Calculate" could not be resolved. (Strategy type BuildPlanStrategy, index 3)

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• Enum Naming Convention - Plural

  - by o.k.w

  I'm asking this question despite having read similar but not exactly what I want at http://stackoverflow.com/questions/495051/c-naming-convention-for-enum-and-matching-property I found I have a tendency to name enums in plural and then 'use' them as singular, example: public enum EntityTypes { Type1, Type2 } public class SomeClass { /* some codes */ public EntityTypes EntityType {get; set;} } Of course it works and this is my style, but can anyone find potential problem with such convention? I do have an "ugly" naming with the word "Status" though: public enum OrderStatuses { Pending, Fulfilled, Error, Blah, Blah } public class SomeClass { /* some codes */ public OrderStatuses OrderStatus {get; set;} } Additional Info: Maybe my question wasn't clear enough. I often have to think hard when naming the variables of the my defined enum types. I know the best practice, but it doesn't help to ease my job of naming those variables. I can't possibly expose all my enum properties (say "Status") as "MyStatus". My question: Can anyone find potential problem with my convention described above? It is NOT about best practice. Question rephrase: Well, I guess I should ask the question this way: Can someone come out a good generic way of naming the enum type such that when used, the naming of the enum 'instance' will be pretty straightforward?

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• dynamically create class in scala, should I use interpreter?

  - by Phil

  Hi, I want to create a class at run-time in Scala. For now, just consider a simple case where I want to make the equivalent of a java bean with some attributes, I only know these attributes at run time. How can I create the scala class? I am willing to create from scala source file if there is a way to compile it and load it at run time, I may want to as I sometimes have some complex function I want to add to the class. How can I do it? I worry that the scala interpreter which I read about is sandboxing the interpreted code that it loads so that it won't be available to the general application hosting the interpreter? If this is the case, then I wouldn't be able to use the dynamically loaded scala class. Anyway, the question is, how can I dynamically create a scala class at run time and use it in my application, best case is to load it from a scala source file at run time, something like interpreterSource("file.scala") and its loaded into my current runtime, second best case is some creation by calling methods ie. createClass(...) to create it at runtime. Thanks, Phil

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• Django - provide additional information in template

  - by Ninefingers

  Hi all, I am building an app to learn Django and have started with a Contact system that currently stores Contacts and Addresses. C's are a many to many relationship with A's, but rather than use Django's models.ManyToManyField() I've created my own link-table providing additional information about the link, such as what the address type is to the that contact (home, work etc). What I'm trying to do is pass this information out to a view, so in my full view of a contact I can do this: def contact_view_full(request, contact_id): c = get_object_or_404(Contact, id=contact_id) a = [] links = ContactAddressLink.objects.filter(ContactID=c.id) for link in links: b = Address.objects.get(id=link.AddressID_id) a.append(b) return render_to_response('contact_full.html', {'contact_item': c, 'addresses' : a }, context_instance=RequestContext(request)) And so I can do the equivalent of c.Addresses.all() or however the ManyToManyField works. What I'm interested to know is how can I pass out information about the link in the link object with the 'addresses' : a information, so that when my template does this: {% for address in addresses %} <!-- ... --> {% endfor %} and properly associate the correct link object data with the address. So what's the best way to achieve this? I'm thinking a union of two objects might be an idea but I haven't enough experience with Django to know if that's considered the best way of doing it. Suggestions? Thanks in advance. Nf

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• Genetic Algorithms applied to Curve Fitting

  - by devoured elysium

  Let's imagine I have an unknown function that I want to approximate via Genetic Algorithms. For this case, I'll assume it is y = 2x. I'd have a DNA composed of 5 elements, one y for each x, from x = 0 to x = 4, in which, after a lot of trials and computation and I'd arrive near something of the form: best_adn = [ 0, 2, 4, 6, 8 ] Keep in mind I don't know beforehand if it is a linear function, a polynomial or something way more ugly, Also, my goal is not to infer from the best_adn what is the type of function, I just want those points, so I can use them later. This was just an example problem. In my case, instead of having only 5 points in the DNA, I have something like 50 or 100. What is the best approach with GA to find the best set of points? Generating a population of 100, discard the worse 20% Recombine the remaining 80%? How? Cutting them at a random point and then putting together the first part of ADN of the father with the second part of ADN of the mother? Mutation, how should I define in this kind of problem mutation? Is it worth using Elitism? Any other simple idea worth using around? Thanks

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• Win 7 Privilege Level (Run as administrator) via GP or command line

  - by FinalizedFrustration

  Is there a way to set the Privilege Level for legacy software via group policy or on the command line? I have some legacy software, which we unfortunately cannot move away from. This software requires administrator access. I know I can go into the Properties dialog and check "Run this program as an administrator" on every single instance on every single one of my workstations, but that gets old after the 30th install. If I had my way, we would dump this software, find some software that did what we needed, was fully compliant with Win7 security best-practices and give everyone limited user accounts... However, I am not the boss, so everyone gets administrator accounts. Given that, I suppose I could just tell everyone to open the context menu and choose "Run as administrator", but we have some very, very, VERY low-tech users, and half of them might just choose "Delete" instead. Anyone know of a way to set this option on the command line? or better yet, through Group Policy?

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• Website Upgrade - Avoid Downtime

  - by nolan.sipos

  I have been requested to investigate how I can reduce the downtime of our website upgrades. We maintain a DNN site with both public facing pages and member only pages. The member only pages are directly linked to our core application database while the public pages are not. Our current process is to redirect website users as soon as the upgrade process begins, which includes Backup of the Prod DB Update Prod DB Update Executables (Application) Upgrade Website Application (If this requires an update) Install Dependencies Upgrade sub systems like communication engine and payment broker Update various configuration files Perform testing of systems Restart all services Allow access to site This process can take from 2 to 8 hours depending on upgrade required, scripts to be run, size of database and number or portals. My initial thoughts are to restrict users to read only pages and any update pages would be unavailable. Could anyone please offer suggestions as to the best practices for what I would think to be a common problem so that we can reduce this down time and if we need infrastructure changes, I can put this to our technical department.

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• apache2 mod_proxy configuration for single threaded servers

  - by The Doctor What

  I have a multiple instances of thin running behind apache 2.2's mod_proxy. The problem I have is that a couple pages, by design, take a while to run. If I just configure apache the obvious way (just add the thin urls as BalanceMember lines and no other configurations) then what happens is if someone clicks on the long-running page, then if enough web requests happen while it is running, someone eventually gets the same thin server and has to wait. Does anyone have some best practices or suggested configuration for mod_proxy and thin? Ciao!

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• OleDb database to DataSet and back in c#?

  - by Troy

  I'm writing a program that lets a user: Connect to an (arbitrary) View all of the tables in that database in separate DataGridViews Edit them in the program, generate random data, and see the results Choose to commit those changes or revert So I discovered the DataSet class, which looks like it's capable of holding everything that a database would, and I decided that the best thing to do here would be to load everything into one dataset, let the user edit it, and then save the dataset back to the database. The problem is that the only way I can find to load the database tables is this: set = new DataSet(); DataTable schema = connection.GetOleDbSchemaTable( OleDbSchemaGuid.Tables, new string[] { null, null, null, "TABLE" }); foreach (DataRow row in schema.Rows) { string tableName = row.Field<string>("TABLE_NAME"); DataTable dTable = new DataTable(); new OleDbDataAdapter("SELECT * FROM " + tableName, connection).Fill(dTable); dTable.TableName = tableName; set.Tables.Add(dTable); } while it seems like there should be a simpler way given that datasets appear to be designed for exactly this purpose. The real problem though is when I try saving these things. In order to use the OleDbDataAdapter.Update() method, I'm told that I have to provide valid INSERT queries. Doesn't that kind of negate the whole point of having a class to handle this stuff for me? Anyway, I'm hoping somebody can either explain how to load and save a database into a dataset or maybe give me a better idea of how to do what I'm trying to do. I could always parse the commands together myself, but that doesn't seem like the best solution.

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• Fighting Spam - What can I do as an: Email Administrator, Domain Owner, or User?

  - by Chris S

  This is a Canonical Question about Fighting Spam. Also related: How to stop people from using my domain to send spam? There are so many techniques and so much to know about fighting SPAM. What widely used techniques and technologies are available to Administrator, Domain Owners, and End Users to help keep the junk out of our inboxes? We're looking for an answer that covers different tech from various angles. The accepted answer should include a variety of technologies (eg SPF/SenderID, DomainKeys/DKIM, Graylisting, DNS RBLs, Reputation Services, Filtering Software [SpamAssassin, etc]); best practices (eg mail on Port 25 should never be allowed to relay, Port 587 should be used; etc), terminology (eg, Open Relay, Backscatter, MSA/MTA/MUA, Spam/Ham), and possibly other techniques.

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• Useful training courses that aren't specific to a single technology

  - by Dave Turvey

  I have possibly the best problem in the world. I have about £1600 left in a training budget and I need to find something to spend it on. I can spend it on anything that could be considered training. Books, courses, conferences, etc. I would like to find a course that would benifit a software developer but is not about learning a specific programming technology. I don't really want to spend it on a technical training course. These topics are usually best learned with a good book and some trial and error. I have also already been on a general business/management training course and a PRINCE2 project management course. I am currently working on a project on my own so am responsible for communicating with the client, requirements gathering, project management, etc., as well as the coding. What training have you found useful outside the usual technical stuff? Has anyone done any business analysis courses? What were they like? Are there any courses on some of the practicalities of working with software, e.g. automated test and deployment strategies, handling technical support? I would prefer a course in the UK but I can travel if necessary.

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• MySQL Full-Text Search Across Multiple Tables - Quick/Long Solution?

  - by Kerry

  Hello all, I have been doing a bit of research on full-text searches as we realized a series of LIKE statements are terrible. My first find was MySQL full-text searches. I tried to implement this and it worked on one table, failed when I was trying to join multiple tables, and so I consulted stackoverflow's articles (look at the end for a list of the ones I've been to) I didn't see anything that clearly answered my questions. I'm trying to get this done literally in an hour or two (quick solution) but I also want to do a better long term solution. Here is my query: SELECT a.`product_id`, a.`name`, a.`slug`, a.`description`, b.`list_price`, b.`price`, c.`image`, c.`swatch`, e.`name` AS industry FROM `products` AS a LEFT JOIN `website_products` AS b ON (a.`product_id` = b.`product_id`) LEFT JOIN ( SELECT `product_id`, `image`, `swatch` FROM `product_images` WHERE `sequence` = 0) AS c ON (a.`product_id` = c.`product_id`) LEFT JOIN `brands` AS d ON (a.`brand_id` = d.`brand_id`) INNER JOIN `industries` AS e ON (a.`industry_id` = e.`industry_id`) WHERE b.`website_id` = 96 AND b.`status` = 1 AND b.`active` = 1 AND MATCH( a.`name`, a.`sku`, a.`description`, d.`name` ) AGAINST ( 'ashley sofa' ) GROUP BY a.`product_id` ORDER BY b.`sequence` LIMIT 0, 9 The error I get is: Incorrect arguments to MATCH If I remove d.name from the MATCH statement it works. I have a full-text index on that column. I saw one of the articles say to use an OR MATCH for this table, but won't that lose the effectiveness of being able to rank them together or match them properly? Other places said to use UNIONs but I don't know how to do that properly. Any advice would be greatly appreciated. In the idea of a long term solution it seems that either Sphinx or Lucene is best. Now by no means and I a MySQL guru, and I heard that Lucene is a bit more complicated to setup, any recommendations or directions would be great. Articles: http://stackoverflow.com/questions/1117005/mysql-full-text-search-across-multiple-tables http://stackoverflow.com/questions/668371/mysql-fulltext-search-across-1-table http://stackoverflow.com/questions/2378366/mysql-how-to-make-multiple-table-fulltext-search http://stackoverflow.com/questions/737275/pros-cons-of-full-text-search-engine-lucene-sphinx-postgresql-full-text-searc http://stackoverflow.com/questions/1059253/searching-across-multiple-tables-best-practices

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• Suggest a good method with least lookup time complexity

  - by Amrish

  I have a structure which has 3 identifier fields and one value field. I have a list of these objects. To give an analogy, the identifier fields are like the primary keys to the object. These 3 fields uniquely identify an object. Class { int a1; int a2; int a3; int value; }; I would be having a list of say 1000 object of this datatype. I need to check for specific values of these identity key values by passing values of a1, a2 and a3 to a lookup function which would check if any object with those specific values of a1, a2 and a3 is present and returns that value. What is the most effective way to implement this to achieve a best lookup time? One solution I could think of is to have a 3 dimensional matrix of length say 1000 and populate the value in it. This has a lookup time of O(1). But the disadvantages are. 1. I need to know the length of array. 2. For higher identity fields (say 20), then I will need a 20 dimension matrix which would be an overkill on the memory. For my actual implementation, I have 23 identity fields. Can you suggest a good way to store this data which would give me the best look up time?

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• Use Java exceptions internally for REST API user errors?

  - by user303396

  We have a REST API that works great. We're refactoring and deciding how to internally handle errors by the users of our API. For example the user needs to specify the "movie" url parameter which should take the value of "1984", "Crash", or "Avatar". First we check to see if it has a valid value. What would be the best approach if the movie parameter is invalid? return null from one of the internal methods and check for the null in the main API call method throw an exception from the internal method and catch exceptions in the main API method I think it would make our code more readable and elegant to use exceptions. However, we're reluctant because we'd be potentially throwing many exceptions because of user API input errors, our code could be perfect. This doesn't seem to be the proper use of exceptions. If there are heavy performance penalties with exceptions, which would make sense with stack traces needing to be collected, etc., then we're unnecessarily spending resources when all we need to do is tell the user the parameter is wrong. These are REST API methods, so we're not propogating the exceptions to the users of the API, nor would we want to even if possible. So what's the best practice here? Use ugly nulls or use java's exception mechanism?

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• identation control while developing a small python like language

  - by sap

  Hello, Im developing a small python like language using flex, byacc (for lexical and parsing) and C++, but i have a few questions regarding scope control. just as python it uses white spaces (or tabs) for identation, not only that but i want to implement index breaking like for instance if you type "break 2" inside a while loop thats inside another while loop it would not only break from the last one but from the first loop as well (hence the number 2 after break) and so on. example: while 1 while 1 break 2 end end #after break 2 it would jump right here but since i dont have an "anti" tab character to check when a scope ends (like C for example i would just use the '}' char) i was wondering if this method would the the best: i would define a global variable, like "int tabIndex" on my yacc file that i would access in my lex file using extern. then everytime i find a tab character on my lex file i would increment that variable by 1. when parsing on my yacc file if i find a "break" keyword i would decrement by the amount typed after it from the tabIndex variable, and when i reach and EOF after compiling and i get a tabIndex != 0 i would output compilation error. now the problem is, whats the best way to see if the identation got reduced, should i read \b (backspace) chars from lex and then reduce the tabIndex variable (when the user doesnt use break)? another method to achieve this? also just another small question, i want every executable to have its starting point on the function called start() should i hardcode this onto my yacc file? sorry for the long question any help is greatly appretiated. also if someone can provide an yacc file for python would be nice as a guideline (tried looking on google and had no luck). thanks in advance.

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• lseek/write suddenly returns -1 with errno = 9 (Bad file descriptor)

  - by Ger Teunis

  My application uses lseek to seek the desired position to write data. The file is opened using open() command successfully and my application was able to use lseek and wite lots of times. At a given time, for some users and not easily reproducible the lseek returns -1 with an errno of 9. File is not closed before this and the filehandle (int) isn't reset. After this an other file is created open is okay again and lseek and write works again. To make it even worse, this user tried the complete sequence again and all was well. So my question is, can the OS close the file handle for me for some reason? What could cause this? A file indexer or file scanner of some sort? What is the best way to solve this; is this pseudo code the best solution? (never mind the code layout, will create functions for it) int fd=open(...); if (fd>-1) { long result = lseek(fd,....); if (result == -1 && errno==9) { close(fd..); //make sure we try to close nicely fd=open(...); result = lseek(fd,....); } } Anybody experience with something similar? Summary: file seek and write works okay for a given fd and suddenly gives back errno=9 without a reason.

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• Unit Testing - Validation of ViewModel ASP.NET MVC 2

  - by dean nolan

  I am currently unit testing a service that adds users to a repository. I am using dependency injection to test using a fake repository. The repository has a method CreateUser(User user) which just adds it to the database or in this case a List of Users. The logic for the creation is in the UserServices class. The application has a form for creating a user that requires some properties such as name and address. This is an MVC 2 app and I will be using the new validation using data annotations. This makes me wonder about a few things: 1) Should I annotate a POCO object that will map to the database? Or should I create a specific View Model that has these annotations and pass this data to the UserServices class? 2)Should the UserServicesClass also check this data? Would I best be constructing a Usr out of the ViewModel and passing this into the Service as a parameter? 3) The actual unit testing would depend on 2), I either populate a User object and pass that in, or I pass a large list of strings to the method CreateUser. Writing this out I get a basic idea that I should probably annotate the view model only, pass in a user (constructed by the view model if the data is valid) and also just construct the user in the unit test also. Is this the best way to go?

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• Database warehouse design: fact tables and dimension tables

  - by morpheous

  I am building a poor man's data warehouse using a RDBMS. I have identified the key 'attributes' to be recorded as: sex (true/false) demographic classification (A, B, C etc) place of birth date of birth weight (recorded daily): The fact that is being recorded My requirements are to be able to run 'OLAP' queries that allow me to: 'slice and dice' 'drill up/down' the data and generally, be able to view the data from different perspectives After reading up on this topic area, the general consensus seems to be that this is best implemented using dimension tables rather than normalized tables. Assuming that this assertion is true (i.e. the solution is best implemented using fact and dimension tables), I would like to seek some help in the design of these tables. 'Natural' (or obvious) dimensions are: Date dimension Geographical location Which have hierarchical attributes. However, I am struggling with how to model the following fields: sex (true/false) demographic classification (A, B, C etc) The reason I am struggling with these fields is that: They have no obvious hierarchical attributes which will aid aggregation (AFAIA) - which suggest they should be in a fact table They are mostly static or very rarely change - which suggests they should be in a dimension table. Maybe the heuristic I am using above is too crude? I will give some examples on the type of analysis I would like to carryout on the data warehouse - hopefully that will clarify things further. I would like to aggregate and analyze the data by sex and demographic classification - e.g. answer questions like: How does male and female weights compare across different demographic classifications? Which demographic classification (male AND female), show the most increase in weight this quarter. etc. Can anyone clarify whether sex and demographic classification are part of the fact table, or whether they are (as I suspect) dimension tables.? Also assuming they are dimension tables, could someone elaborate on the table structures (i.e. the fields)? The 'obvious' schema: CREATE TABLE sex_type (is_male int); CREATE TABLE demographic_category (id int, name varchar(4)); may not be the correct one.

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