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• Suggestion on UPnP presentation

  - by Microkernel

  Hi all, I am working on an embedded device (bit higher end in terms of system resources but still an embedded one) which has lot of media content in it. I am trying to make it UPnP complaint and want to be able to control this device using a UPnP complaint control point/companion device like ipad. The step towards this is to be able to present the playlist content to the user. We thought of using HTML5 as a format to use. But as I am a noob in web technologies, I am not sure whats the best way to produce and present rich dynamic web pages. The content thats presented are video/audio listing that device can play and want this listing to be generated using the user's input criteria. So, what would be the best way to generate these dynamic pages which are rich and rendered as HTML5 pages. (looked at XML & XSLT, but there seems to be some limitations in how well one can use XSLT from some rewviews I saw). Thanks Microkernel PS: This may be silly or very basic as I am a embedded systems developer and not even a noob in web technologoes...

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• Examples using Active Directory/LDAP groups for permissions \ roles in Rails App.

  - by Nick Gorbikoff

  Hello. I was wondering how other people implemented this scenario. I have an internal rails app ( inventory management, label printing, shipping,etc). I'm rewriting security on the system, cause the old way got to cumbersome to maintain ( users table, passwords, roles) - I used restful_authentication and roles. It was implemented about 3 years ago. I already implemented AuthLogic with ruby-ldap-net to authenticate users ( actually that was surprisingly easy, compared to how I struggled with other frameworks/languages before). Next step is roles. I already have groups defined in Active Directory - so I don't want to run a separate roles system in my rails app, I just want to reuse Active Directory groups - since that part of the system is already maintained for other purposes ( shared drives, backups, pc access, etc) So I was wondering if others had experience implementing permissions/roles in a rails app based on groups in Active Directory or LDAP. Also the roles requirements are pretty complex. Here is an example: For instance I have users that belong to the supervisors group in AD and to inventory dept, so I was that user to be able to run "advanced" tasks in invetory - adjust qty, run reports, however other "supervisors" from other departmanets, shouldn't be able to do this, also Top Management - should be able to use those reports (regardless weather they belong to the invetory or not), but not Middle Management, unless they are in inventory group. Admins of the system (Domain Admins) should have unrestricted access to the system , except for HR & Finances part unless they are in HR ( like you don't want all system admins (except for one authorized one) to see personal info of other employees). I looked at acl9, cancan, aegis. I was wondering if there are any advantaged/cons to using one versus the other for this particular use of system access based on AD. Suggest other systems if you had good experience. Thank you!!!

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• C++ destructors causing crash's

  - by larsonator

  ok, so i got a some what intricate program that simulates the uni systems of students, units, and students enrolling in units. Students are stored in a binary search tree, Units are stored in a standard list. Student has a list of Unit Pointers, to store which units he/she is enrolled in Unit has a list of Student pointers, to store students which are enrolled in that unit. The unit collections (storing units in a list) as made as a static variable where the main function is, as is the Binary search tree of students. when its finaly time to close the program, i call the destructors of each. but at some stage, during the destructors on the unit side, Unhandled exception at 0x002e4200 in ClassAllocation.exe: 0xC0000005: Access violation reading location 0x00000000. UnitCollection destructor: UnitCol::~UnitCol() { list<Unit>::iterator itr; for(itr = UnitCollection.begin(); itr != UnitCollection.end();) { UnitCollection.pop_front(); itr = UnitCollection.begin(); } } Unit Destructor Unit::~Unit() { } now i got the same sorta problem on the student side of things BST destructors void StudentCol::Destructor(const BTreeNode * r) { if(r!= 0) { Destructor(r->getLChild()); Destructor(r->getRChild()); delete r; } } StudentCol::~StudentCol() { Destructor(root); } Student Destructor Student::~Student() { } so yeah any help would be greatly appreciated

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• Leveraging hobby experience to get a job

  - by Bernard

  Like many other's I began programming at an early age. I started when I was 11 and I learned C when I was 14 (now 26). While most of what I did were games just to entertain myself I did everything from low level 2D graphics, and binary I/O, to interfacing with free API's, custom file systems, audio, 3D animations, OpenGL, web sites, etc. I worked on a wide variety of things trying to make various games. Because of this experience I have tested out of every college level C/C++ programming course I have ever been offered. In the classes I took, my classmates would need a week to do what I finished in class with an hour or two of work. I now have my degree now and I have 2 years of experience working full time as a web developer however I would like to get back into C++ and hopefully do simulation programming. Unfortunately I have yet to do C++ as a job, I have only done it for testing out of classes and doing my senior project in college. So most of what I have in C++ is still hobby experience and I don't know how to best convey that so that I don't end up stuck doing something too low level for me. Right now I see a job offer that requires 2 years of C++ experience, but I have at least 9 (I didn't do C++ everyday for the last 14 years). How do I convey my experience? How much is it truly worth? and How do I get it's full value? The best thing that I can think of is a demo and a portfolio, however that only comes into play after an interview has been secured. I used a portfolio to land my current job. All answers and advice are appreciated.

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• Using jQuery with Windows 8 Metro JavaScript App causes security error

  - by patridge

  Since it sounded like jQuery was an option for Metro JavaScript apps, I was starting to look forward to Windows 8 dev. I installed Visual Studio 2012 Express RC and started a new project (both empty and grid templates have the same problem). I made a local copy of jQuery 1.7.2 and added it as a script reference. <!-- SomeTestApp references --> <link href="/css/default.css" rel="stylesheet" /> <script src="/js/jquery-1.7.2.js"></script> <script src="/js/default.js"></script> Unfortunately, as soon as I ran the resulting app it tosses out a console error: HTML1701: Unable to add dynamic content ' a' A script attempted to inject dynamic content, or elements previously modified dynamically, that might be unsafe. For example, using the innerHTML property to add script or malformed HTML will generate this exception. Use the toStaticHTML method to filter dynamic content, or explicitly create elements and attributes with a method such as createElement. For more information, see http://go.microsoft.com/fwlink/?LinkID=247104. I slapped a breakpoint in a non-minified version of jQuery and found the offending line: div.innerHTML = " <link/><table></table><a href='/a' style='top:1px;float:left;opacity:.55;'>a</a><input type='checkbox'/>"; Apparently, the security model for Metro apps forbids creating elements this way. This error doesn't cause any immediate issues for the user, but given its location, I am worried it will cause capability-discovery tests in jQuery to fail that shouldn't. I definitely want jQuery $.Deferred for making just about everything easier. I would prefer to be able to use the selector engine and event handling systems, but I would live without them if I had to. How does one get the latest jQuery to play nicely with Metro development?

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• File descriptor limits and default stack sizes

  - by Charles

  Where I work we build and distribute a library and a couple complex programs built on that library. All code is written in C and is available on most 'standard' systems like Windows, Linux, Aix, Solaris, Darwin. I started in the QA department and while running tests recently I have been reminded several times that I need to remember to set the file descriptor limits and default stack sizes higher or bad things will happen. This is particularly the case with Solaris and now Darwin. Now this is very strange to me because I am a believer in 0 required environment fiddling to make a product work. So I am wondering if there are times where this sort of requirement is a necessary evil, or if we are doing something wrong. Edit: Great comments that describe the problem and a little background. However I do not believe I worded the question well enough. Currently, we require customers, and hence, us the testers, to set these limits before running our code. We do not do this programatically. And this is not a situation where they MIGHT run out, under normal load our programs WILL run out and seg fault. So rewording the question, is requiring the customer to change these ulimit values to run our software to be expected on some platforms, ie, Solaris, Aix, or are we as a company making it to difficult for these users to get going? Bounty: I added a bounty to hopefully get a little more information on what other companies are doing to manage these limits. Can you set these pragmatically? Should we? Should our programs even be hitting these limits or could this be a sign that things might be a bit messy under the covers? That is really what I want to know, as a perfectionist a seemingly dirty program really bugs me.

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• How to create nested ViewComponents in Monorail and NVelocity?

  - by rob_g

  I have been asked to update the menu on a website we maintain. The website uses Castle Windors Monorail and NVelocity as the template. The menu is currently rendered using custom made subclasses of ViewComponent, which render li elements. At the moment there is only one (horizontal) level, so the current mechanism is fine. I have been asked to add drop down menus to some of the existing menus. As this is the first time I have seen Monorail and NVelocity, I'm a little lost. What currently exists: <ul> #component(MenuComponent with "title=Home" "hover=autoselect" "link=/") #component(MenuComponent with "title=Videos" "hover=autoselect") #component(MenuComponent with "title=VPS" "hover=autoselect" "link=/vps") #component(MenuComponent with "title=Add-Ons" "hover=autoselect" "link=/addons") #component(MenuComponent with "title=Hosting" "hover=autoselect" "link=/hosting") #component(MenuComponent with "title=Support" "hover=autoselect" "link=/support") #component(MenuComponent with "title=News" "hover=autoselect" "link=/news") #component(MenuComponent with "title=Contact Us" "hover=autoselect" "link=/contact-us") </ul> Is it possible to have nested MenuComponents (or a new SubMenuComponent) something like: <ul> #component(MenuComponent with "title=Home" "hover=autoselect" "link=/") #component(MenuComponent with "title=Videos" "hover=autoselect") #blockcomponent(MenuComponent with "title=VPS" "hover=autoselect" "link=/vps") #component(SubMenuComponent with "title="Plans" "hover=autoselect" "link=/vps/plans") #component(SubMenuComponent with "title="Operating Systems" "hover=autoselect" "link=/vps/os") #component(SubMenuComponent with "title="Supported Applications" "hover=autoselect" "link=/vps/apps") #end #component(MenuComponent with "title=Add-Ons" "hover=autoselect" "link=/addons") #component(MenuComponent with "title=Hosting" "hover=autoselect" "link=/hosting") #component(MenuComponent with "title=Support" "hover=autoselect" "link=/support") #component(MenuComponent with "title=News" "hover=autoselect" "link=/news") #component(MenuComponent with "title=Contact Us" "hover=autoselect" "link=/contact-us") </ul> I need to draw the sub menu (ul and li elements) inside the overridden Render method on MenuComponent, so using nested ViewComponent derivatives may not work. I would like a method keep the basically declarative method for creating menus, if at all possible.

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• Random-access archive for Unix use

  - by tylerl

  I'm looking for a good format for archiving entire file-systems of old Linux computers. TAR.GZ The tar.gz format is great for archiving files with UNIX-style attributes, but since the compression is applied across the entire archive, the design precludes random-access. Instead, if you want to access a file at the end of the archive, you have to start at the beginning and decompress the whole file (which could be several hundred GB) up to the point where you find the entry you're looking for. ZIP Conversely, one selling point of the ZIP format is that it stores an index of the archive: filenames are stored separately with pointers to the location within the archive were to find the data. If I want to extract a file at the end, I look up the position of that file by name, seek to the location, and extract the data. However, it doesn't store file attributes such as ownership, permissions, symbolic links, etc. Other options? I've tried using squashfs, but it's not really designed for this purpose. The file format is not consistent between versions, and building the archive takes a lot of time and space. What other options might suit this purpose better?

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• Would making plain int 64-bit break a lot of reasonable code?

  - by R..

  Until recently, I'd considered the decision by most systems implementors/vendors to keep plain int 32-bit even on 64-bit machines a sort of expedient wart. With modern C99 fixed-size types (int32_t and uint32_t, etc.) the need for there to be a standard integer type of each size 8, 16, 32, and 64 mostly disappears, and it seems like int could just as well be made 64-bit. However, the biggest real consequence of the size of plain int in C comes from the fact that C essentially does not have arithmetic on smaller-than-int types. In particular, if int is larger than 32-bit, the result of any arithmetic on uint32_t values has type signed int, which is rather unsettling. Is this a good reason to keep int permanently fixed at 32-bit on real-world implementations? I'm leaning towards saying yes. It seems to me like there could be a huge class of uses of uint32_t which break when int is larger than 32 bits. Even applying the unary minus or bitwise complement operator becomes dangerous unless you cast back to uint32_t. Of course the same issues apply to uint16_t and uint8_t on current implementations, but everyone seems to be aware of and used to treating them as "smaller-than-int" types.

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• How to populate a listview in ASP.NET 3.5 through a dataset?

  - by EasyDot

  Is it possible to populate a listview with a dataset? I have a function that returns a dataset. Why im asking this is because my SQL is quite complicated and i can't convert it to a SQLDataSource... Public Function getMessages() As DataSet Dim dSet As DataSet = New DataSet Dim da As SqlDataAdapter Dim cmd As SqlCommand Dim SQL As StringBuilder Dim connStr As StringBuilder = New StringBuilder("") connStr.AppendFormat("server={0};", ConfigurationSettings.AppSettings("USERserver").ToString()) connStr.AppendFormat("database={0};", ConfigurationSettings.AppSettings("USERdb").ToString()) connStr.AppendFormat("uid={0};", ConfigurationSettings.AppSettings("USERuid").ToString()) connStr.AppendFormat("pwd={0};", ConfigurationSettings.AppSettings("USERpwd").ToString()) Dim conn As SqlConnection = New SqlConnection(connStr.ToString()) Try SQL = New StringBuilder cmd = New SqlCommand SQL.Append("SELECT m.MESSAGE_ID, m.SYSTEM_ID, m.DATE_CREATED, m.EXPIRE_DATE, ISNULL(s.SYSTEM_DESC,'ALL SYSTEMS') AS SYSTEM_DESC, m.MESSAGE ") SQL.Append("FROM MESSAGE m ") SQL.Append("LEFT OUTER JOIN [SYSTEM] s ") SQL.Append("ON m.SYSTEM_ID = s.SYSTEM_ID ") SQL.AppendFormat("WHERE m.SYSTEM_ID IN ({0}) ", sSystems) SQL.Append("OR m.SYSTEM_ID is NULL ") SQL.Append("ORDER BY m.DATE_CREATED DESC; ") SQL.Append("SELECT mm.MESSAGE_ID, mm.MODEL_ID, m.MODEL_DESC ") SQL.Append("FROM MESSAGE_MODEL mm ") SQL.Append("JOIN MODEL m ") SQL.Append(" ON m.MODEL_ID = mm.MODEL_ID ") cmd.CommandText = SQL.ToString cmd.Connection = conn da = New SqlDataAdapter(cmd) da.Fill(dSet) dSet.Tables(0).TableName = "BASE" dSet.Tables(1).TableName = "MODEL" Return dSet Catch ev As Exception cLog.EventLog.logError(ev, cmd) Finally 'conn.Close() End Try End Function

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• Algorithm for assigning a unique series of bits for each user?

  - by Mark

  The problem seems simple at first: just assign an id and represent that in binary. The issue arises because the user is capable of changing as many 0 bits to a 1 bit. To clarify, the hash could go from 0011 to 0111 or 1111 but never 1010. Each bit has an equal chance of being changed and is independent of other changes. What would you have to store in order to go from hash - user assuming a low percentage of bit tampering by the user? I also assume failure in some cases so the correct solution should have an acceptable error rate. I would an estimate the maximum number of bits tampered with would be about 30% of the total set. I guess the acceptable error rate would depend on the number of hashes needed and the number of bits being set per hash. I'm worried with enough manipulation the id can not be reconstructed from the hash. The question I am asking I guess is what safe guards or unique positioning systems can I use to ensure this happens.

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• How to justify using a scripting language as part of a project

  - by sylvanaar

  I have a specific project in which I want to use either a scripting language + C, or as an alternative a 100% Java solution. The program adapts a legacy system for use with other moderns systems. Basically, I have few choices as to what language I can use. I have C/C++, Java 1.4, and I have also compiled the Lua for this environment. The program does 'screen scraping' and has to deal with alot of strings. That part of the code is highly variable. Most of the developers at my company use C, so - my original design was to write some portions in C, and use Lua for the part that dealt with strings and changed freqently. I was told 'You have to justify your use of the scripting language.' So i reworked my design using 100% Java, and was told - Java wont have enough performance. You should do the whole thing in C. I'm not controlling lasers or doing image processing - just some screen scraping. I still have to provide justification for using anything but C - so what justification can I provide?

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• Looking to reimplement build toolchain from bash/grep/sed/awk/(auto)make/configure to something more

  - by wash

  I currently maintain a few boxes that house a loosely related cornucopia of coding projects, databases and repositories (ranging from a homebrew *nix distro to my class notes), maintained by myself and a few equally pasty-skinned nerdy friends (all of said cornucopia is stored in SVN). The vast majority of our code is in C/C++/assembly (a few utilities are in python/perl/php, we're not big java fans), compiled in gcc. Our build toolchain typically consists of a hodgepodge of make, bash, grep, sed and awk. Recent discovery of a Makefile nearly as long as the program it builds (as well as everyone's general anxiety with my cryptic sed and awking) has motivated me to seek a less painful build system. Currently, the strongest candidate I've come across is Boost Build/Bjam as a replacement for GNU make and python as a replacement for our build-related bash scripts. Are there any other C/C++/asm build systems out there worth looking into? I've browsed through a number of make alternatives, but I haven't found any that are developed by names I know aside from Boost's. (I should note that an ability to easily extract information from svn commandline tools such as svnversion is important, as well as enough flexibility to configure for builds of asm projects as easily as c/c++ projects)

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• How to decrypt a string encrypted with HMACSHA1?

  - by Bob

  I'm an encryption novice trying to pass some values back and forth between systems. I can encrypt the value, but can't seem to figure out how to decrypt on the other end. I've created a simple Windows Forms application using VB.NET. Trying to input a value and a key, encrypt and then decrypt to get the original value. Here's my code so far. Any help greatly appreciated. Thanks. Imports System Imports System.IO Imports System.Security.Cryptography Imports System.Text Public Class Form1 Private Sub btnEncode_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnEncode.Click Dim hmacsha1 As New HMACSHA1(Encoding.ASCII.GetBytes(txtKey.Text)) Dim hashValue As Byte() = hmacsha1.ComputeHash(Encoding.ASCII.GetBytes(txtValue.Text)) txtResult.Text = BytesToHexString(hashValue) hmacsha1.Clear() End Sub Private Sub btnDecode_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDecode.Click '??? End Sub Private Function BytesToHexString(ByVal bytes As Byte()) As String Dim output As String = String.Empty Dim i As Integer = 0 Do While i < bytes.Length output += bytes(i).ToString("X2") i += 1 Loop Return output End Function End Class

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• Document management, SCM ?

  - by tsunade

  Hello, This might not be a hard core programming question, but it's related to some of the tools used by programmers I suspect. So we're a bunch of people each with a bunch of documents and a bunch of different computers on a bunch of operating systems (well, only 2, linux and windows). The best way these documents can be stored/managed is if they were available offline (the laptop might not always be online) but also synchronized between all the machines. Having a server with extra reliable storage be a "base repository" seems like a good idea to me. Using a SCM comes to my mind and I've tried Subversion, and it seems to be a good thing that it uses a centralized repository - but: When checking out the total size of the checkout is roughly double the original size. Big files or big repositories seem to slow it down. Also I've tried rsync, which might work - but it's a bit rough when it comes to the potential conflict. Finally I've tried Unison (which is a wrapping of rsync, I think) and while it works it becomes horribly slow for the big directories we have here since it has to scan everything. So the question is - is there a SCM tool out there that is actually practial to use for a big bunch of both small and big files? If thats a NO - does anyone know other tools that do this job? Thanks for reading :)

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• Projects integration question

  - by qkrsppopcmpt

  Other team has one legacy system, which is data aggregators. It is implemented as web service using JAVA, SOAP,MTOM,Tomcat and Axis2. They have wsdl files defining functionalities such as search, retrieve data, upload, download. Our team has a new developed website which is developed using RoR with mySQL. It is sort of social networking. Users can register, add friends, upload images, videos. Also, they can search data. We are required to connect the two systems. One possible solution I think is - Adding components into our website. The component invoke services on the aggregators. - Synchronize website database to the aggregators. My doubts are: 1. How to add components in our websites? The components should use Java or Ruby or adapter from java to ruby. It is possible using ruby invoke web service. I think it should work since it is the point of web service. If so, can ruby call those services in wsdl directly? But how to deal with those different data structure? How to synchroinze our database to the aggregators. I think the best way is also through web service invocation such as upload. That means, we have to export the db records into xml files and then write some tools to upload. The web service project support MTOM. So, it is fine to upload huge data. Am I on the right record? Can anybody give me some hint. Thanks.

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• Does anyone know of any good open source voting software?

  - by mezoid

  I'm looking for a voting system that we can implement at work amongst our developers. We need something that allows developers to submit ideas about what we can do to improve our development practices (amongst other things) and then have all the developers vote on the ideas to give everyone an idea of what ideas we should attempt to implement first. For example, our developers could list ideas for parts of our code base that should be improved/cleaned up and we'd be able to collectively vote on which parts to start on first. Something like www.uservoice.com might be one way of getting what we need but I'm still wanting to look at alternatives. Unfortunately, googling for voting and polling systems just doesn't seem to bring up any useful results because most of them seem geared towards elections and surveys rather than a way for people to make suggestions and vote on them. Does anyone here know of any sort of software system that might be able to do what I'm looking for? Better yet, does anyone have such a system set up for the developers at their work place? I'd be interested in knowing if it is useful at all.

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• Integer array or struct array - which is better?

  - by MusiGenesis

  In my app, I'm storing Bitmap data in a two-dimensional integer array (int[,]). To access the R, G and B values I use something like this: // read: int i = _data[x, y]; byte B = (byte)(i >> 0); byte G = (byte)(i >> 8); byte R = (byte)(i >> 16); // write: _data[x, y] = BitConverter.ToInt32(new byte[] { B, G, R, 0 }, 0); I'm using integer arrays instead of an actual System.Drawing.Bitmap because my app runs on Windows Mobile devices where the memory available for creating bitmaps is severely limited. I'm wondering, though, if it would make more sense to declare a structure like this: public struct RGB { public byte R; public byte G; public byte B; } ... and then use an array of RGB instead of an array of int. This way I could easily read and write the separate R, G and B values without having to do bit-shifting and BitConverter-ing. I vaguely remember something from days of yore about byte variables being block-aligned on 32-bit systems, so that a byte actually takes up 4 bytes of memory instead of just 1 (but maybe this was just a Visual Basic thing). Would using an array of structs (like the RGB example` above) be faster than using an array of ints, and would it use 3/4 the memory or 3 times the memory of ints?

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• how to upgrade compact framework applications?

  - by Derick Bailey

  i'm looking for a way to manage application upgrades for my compact framework app. let's say i have v1 of the app installed on my device, and v1.1 has been released. I want the app to make a call to my server to see if there is a new version. since a new version is found, i want to send down the new version of the app to the device and have it installed, replacing the old version. my first thought was just to have the app download the .cab file and kick off the cab file just before exiting the app. this would mostly get the job done but it would prompt the user to pick the installation location if they have a storage card or other partitions on their device. i would like to prevent any user input and just have the new version of the app installed, replacing the old app. i'm certain that there are others doing this already and i don't want to reinvent the wheel, here. what application management tools and systems exist for this type of process? how can I facilitate this type of process?

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

  - by Pawel

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

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• 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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• Where clause on joined table used for user defined key/value pairs

  - by Steve Wright

  Our application allows administrators to add “User Properties” in order for them to be able to tailor the system to match their own HR systems. For example, if your company has departments, you can define “Departments” in the Properties table and then add values that correspond to “Departments” such as “Jewelry”, “Electronics” etc… You are then able to assign a department to users. Here is the schema: In this schema, a User can have only one UserPropertyValue per Property, but doesn’t have to have a value for the property. I am trying to build a query that will be used in SSRS 2005 and also have it use the PropertyValues as the filter for users. My query looks like this: SELECT UserLogin, FirstName, LastName FROM Users U LEFT OUTER JOIN UserPropertyValues UPV ON U.ID = UPV.UserID WHERE UPV.PropertyValueID IN (1, 5) When I run this, if the user has ANY of the property values, they are returned. What I would like to have is where this query will return users that have values BY PROPERTY. So if PropertyValueID = 1 is of Department (Jewelry), and PropertyValueID = 5 is of EmploymentType (Full Time), I want to return all users that are in Department Jewelry that are EmployeeType of Full Time, can this be done? Here's a full data example: User A has Department(Jewelry value = 1) and EmploymentType(FullTime value = 5)User B has Department(Electronics value = 2) and EmploymentType(FullTime value = 5)User C has Department(Jewelry value = 1) and EmployementType(PartTime value = 6) My query should only return User A using the above query UPDATE: I should state that this query is used as a dataset in SSRS, so the parameter passed to the query will be @PropertyIDs and it is defined as a multi-value parameter in SSRS. WHERE UPV.PropertyValueID IN (@PropertyIDs)

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• In which domains are message oriented middleware like AMQP useful?

  - by cocotwo

  What problem do MOM (Message Oriented Middleware) solve? Scalability? Integration? In which domain are they typically used and in which domains are they typically not used? For example, say, is Google using such solution for it's main search engine or to power GMail? What about big websites like Walmart, eBay, FedEx (pretty much a Java shop) and buy.com (pretty much an MS shop)? Does MOM solve a need there? Does it make any sense when you're writing a Webapp where you control the server-side and have an homogenous environment (say tens of Amazon EC2 instances all running Linux + Java JVMs) there and where the clients are, well, Web browsers? Does it make sense for desktop apps that need to communicate with a server? Or is it 'only' for big enterprise stuff where you typically have a happy mix of countless of different systems that needs to communicate in a way or another? I'm a bit confused as to what they're useful for and I think that with example of where they're appropriate and where they're not appropriate I could better understand their use.

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• CMS for managing plain-text content, with tagging

  - by user575606

  Hi, We have some quite-specific requirements for our app that a CMS may help us with, and were hoping that someone may know of a CMS that matches these requirements (it's quite a laborous task to download each CMS and verify this manually). We want a CMS to allow users to create and manage articles, but storing the articles in plain-text only. All of the CMSs that we have looked at so far are geared towards creating HTML pages. We want the CMS to manage workflow (approval process), and tracking of history. The requirements for plain text only is that the intent is to allow business people to generate content which we are going to display in our Silverlight application - we don't want to go down the route of hosting and displaying arbitrary HTML in the app as we want the styling to be seamless with our app, amongst other reasons. We would also want to allow the user to be able to link between articles, but not to external sites (i.e. HTML with no formatting, or some other way of specifying article links), and the third requirement is the ability to tag articles and search on articles. Does anyone know of any non-HTML targetted CMS systems that may match these requirements? Thanks, Gary

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• Handling close-to-impossible collisions on should-be-unique values

  - by balpha

  There are many systems that depend on the uniqueness of some particular value. Anything that uses GUIDs comes to mind (eg. the Windows registry or other databases), but also things that create a hash from an object to identify it and thus need this hash to be unique. A hash table usually doesn't mind if two objects have the same hash because the hashing is just used to break down the objects into categories, so that on lookup, not all objects in the table, but only those objects in the same category (bucket) have to be compared for identity to the searched object. Other implementations however (seem to) depend on the uniqueness. My example (that's what lead me to asking this) is Mercurial's revision IDs. An entry on the Mercurial mailing list correctly states The odds of the changeset hash colliding by accident in your first billion commits is basically zero. But we will notice if it happens. And you'll get to be famous as the guy who broke SHA1 by accident. But even the tiniest probability doesn't mean impossible. Now, I don't want an explanation of why it's totally okay to rely on the uniqueness (this has been discussed here for example). This is very clear to me. Rather, I'd like to know (maybe by means of examples from your own work): Are there any best practices as to covering these improbable cases anyway? Should they be ignored, because it's more likely that particularly strong solar winds lead to faulty hard disk reads? Should they at least be tested for, if only to fail with a "I give up, you have done the impossible" message to the user? Or should even these cases get handled gracefully? For me, especially the following are interesting, although they are somewhat touchy-feely: If you don't handle these cases, what do you do against gut feelings that don't listen to probabilities? If you do handle them, how do you justify this work (to yourself and others), considering there are more probable cases you don't handle, like a supernonva?

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