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• Spring - Transaction Readonly

  - by AAK

  Hello Gurus! Just wanted your expert opinions on declarative transaction management for Spring. Here is my setup - A. DAO Layer is Plain old JDBC using jdbcTemplete (No hibernate etc) B. Service Layer is POJO with declarative trasnactions as follows - save*, readonly=false, rollback for Throwable Things work fine with above setup. However when I say get*, readonly=true I see errors in my log file saying - Database connection cannot be marked as readonly. This happens for all get* methods in Service Layer. Now my questions - A. Do I have to say get* as readonly? All my get* methods are pure read DB operations. I do not wish to run them in any transaction context. How serious is the above error? B. When I remove the get* confiiguration, I do not see the errors, morever all my simple get* operations are performed without transactions. Is this the way to go? C. Why would anyone want to have transactional methods where readonly = true? Is there any practical significance of this configuration? Thank you! As always your resposes are much appreciated!

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• Codeplex/Sourceforge for internal use

  - by Josh

  I'm looking for a free/open source collaborative project manager that can be deployed internally in my workplace that would act similar to Codeplex or Sourceforge. Does anyone know of something like this, and if so do you have experience with it. Requirements: Open Source or Free Locally Deployable Has the same types of features found in Sourceforge / Codeplex Issue/Feature Tracking Community Interaction (ie. Voting, Roles, etc.) SCM Integration (Optional) .NET/Windows Friendly (Optional) Every business ends up having internal utilities, and domain specific apps that developers create to make life easier. Given the input of the internal developer community they have the potential to become much better (can you say GMail...), and I would simply like to foster such an environment internally by providing an easy place for that interaction to take place. UPDATE: So I like what I am seeing in both Trac and GForge, but both are heavily geared towards UNIX/Subversion environments. I should have specified this, but we are a MS shop from top to bottom. How practical do you think it is going to be to try and use these in a MS .NET environment? Would that be like trying to shove a square peg through a round hole?

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• Help needed in grokking password hashes and salts

  - by javafueled

  I've read a number of SO questions on this topic, but grokking the applied practice of storing a salted hash of a password eludes me. Let's start with some ground rules: a password, "foobar12" (we are not discussing the strength of the password). a language, Java 1.6 for this discussion a database, postgreSQL, MySQL, SQL Server, Oracle Several options are available to storing the password, but I want to think about one (1): Store the password hashed with random salt in the DB, one column Found on SO and elsewhere is the automatic fail of plaintext, MD5/SHA1, and dual-columns. The latter have pros and cons MD5/SHA1 is simple. MessageDigest in Java provides MD5, SHA1 (through SHA512 in modern implementations, certainly 1.6). Additionally, most RDBMSs listed provide methods for MD5 encryption functions on inserts, updates, etc. The problems become evident once one groks "rainbow tables" and MD5 collisions (and I've grokked these concepts). Dual-column solutions rest on the idea that the salt does not need to be secret (grok it). However, a second column introduces a complexity that might not be a luxury if you have a legacy system with one (1) column for the password and the cost of updating the table and the code could be too high. But it is storing the password hashed with a random salt in single DB column that I need to understand better, with practical application. I like this solution for a couple of reasons: a salt is expected and considers legacy boundaries. Here's where I get lost: if the salt is random and hashed with the password, how can the system ever match the password? I have theory on this, and as I type I might be grokking the concept: Given a random salt of 128 bytes and a password of 8 bytes ('foobar12'), it could be programmatically possible to remove the part of the hash that was the salt, by hashing a random 128 byte salt and getting the substring of the original hash that is the hashed password. Then re hashing to match using the hash algorithm...??? So... any takers on helping. :) Am I close?

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• what libraries or platforms should I use to build web apps that provide real-time, asynchronous data

  - by Daniel Sterling

  This is a less a question with a simple, practical answer and more a question to foster discussion on the real-time data exchange topic. I'll begin with an example: Google Wave is, at its core, a real-time asynchronous data synchronization engine. Wave supports (or plans to support) concurrent (real-time) document collaboration, disconnected (offline) document editing, conflict resolution, document history and playback with attribution, and server federation. A core part of Wave is the Operational Transformation engine: http://www.waveprotocol.org/whitepapers/operational-transform The OT engine manages document state. Changes between clients are merged and each client has a sane and consistent view of the document at all times; the final document is eventually consistent between all connected clients. My question is: is this system abstract or general enough to be used as a library or generic framework upon which to build web apps that synchronize real-time, asynchronous state in each client? Is the Wave protocol directly used by any current web applications (besides Google's client)? Would it make sense to directly use it for generic state synchronization in a web app? What other existing libraries or frameworks would you consider using when building such a web app? How much code in such an app might be domain-specific logic vs generic state synchronization logic? Or, put another way, how leaky might the state synchronization abstractions be? Comments and discussion welcomed!

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• is there an equivalent of a trigger for general stored procedure execution on sql server

  - by Arj

  Hi All, Hope you can help. Is there a way to detect when a stored proc is being run on SQL Server without altering the SP itself? Here's the requirement. We need to track users running reports from our enterprise data warehouse as the core product we use doesn't allow for this. Both core product reports and a slew of in-house ones we've added all return their data from individual stored procs. We don't have a practical way of altering the parts of the product webpages where reports are called from. We also can't change the stored procs for the core product reports. (It would be trivial to add a logging line to the start/end of each of our inhouse ones). What I'm trying to find therefore, is whether there's a way in SQL Server (2005 / 2008) to execute a logging stored proc whenever any other stored procedure runs, without altering those stored procedures themselves. We have general control over the SQL Server instance itself as it's local, we just don't want to change the product stored procs themselves. Any one have any ideas? Is there a kind of "stored proc executing trigger"? Is there an event model for SQL Server that we can hook custom .Net code into? (Just to discount it from the start, we want to try and make a change to SQL Server rather than get into capturing the report being run from the products webpages etc) Thoughts appreciated Thanks

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• Yet another Haskell vs. Scala question

  - by Travis Brown

  I've been using Haskell for several months, and I love it—it's gradually become my tool of choice for everything from one-off file renaming scripts to larger XML processing programs. I'm definitely still a beginner, but I'm starting to feel comfortable with the language and the basics of the theory behind it. I'm a lowly graduate student in the humanities, so I'm not under a lot of institutional or administrative pressure to use specific tools for my work. It would be convenient for me in many ways, however, to switch to Scala (or Clojure). Most of the NLP and machine learning libraries that I work with on a daily basis (and that I've written in the past) are Java-based, and the primary project I'm working for uses a Java application server. I've been mostly disappointed by my initial interactions with Scala. Many aspects of the syntax (partial application, for example) still feel clunky to me compared to Haskell, and I miss libraries like Parsec and HXT and QuickCheck. I'm familiar with the advantages of the JVM platform, so practical questions like this one don't really help me. What I'm looking for is a motivational argument for moving to Scala. What does it do (that Haskell doesn't) that's really cool? What makes it fun or challenging or life-changing? Why should I get excited about writing it?

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• Is there a way to trace through only project source in Delphi?

  - by Justin

  I'm using Delphi 2010 and I'm wondering if there's a way to trace through code which is in the project without tracing through calls to included VCLs. For example - you put in a breakpoint and then use Shift+F7 to trace through line-by-line. Now you run into a call to some lengthy procedure in a VCL - in my case it's often a Measurement Studio or other component that draws the doodads for a bunch of I/O, OPC, or other bits. At any rate, what happens is that the debugger hops out of the active source file, opens the component source, and traces through that line by line. Often this is hundreds or thousands of lines of code I don't care about - I just want to have it execute and return to the next source line in MY project. Obviously you can do this by setting breakpoints around every instance of an external call, but often there are too many to make this practical - I'd be spending an hour setting a hundred breakpoints every time I wanted to step through a section of code. Is there a setting or a tool somewhere that can do this? Allow one to trace through code within the project while silently executing code which is external to the project? Thanks in advance, Stack Overflow!

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• Netlogo: error when putting variable in table, only constants allowe??

  - by Chantal

  Hello, Currently I am working on a Netlogo program where I need to use nodes and links for vehicle routing problem. (links are called streets in the program) Here I have some practical problems of how to input variable linkspeed in a table with another node. Constants like 200 etc are fine. Online I found some examples where variables are used, but I do not know why I keep getting the following error: Expected a constant. (or why netlogo expects a constant) Here is the relevant piece of code: extensions [table] streets-own [linkspeed linktoll] nodes-own [netw] ;; In another piece of code linkspeed is assigned successfully to the links to cheapcalc ;; start conditions set costs very high 300000 ;; state 3 unsearched state 2 searching state 1 searched (for later purposes) ask nodes [ set i 0 set j count nodes set netw table:make while [i < j][ table:put netw (i) [3000000 3] set i (i + 1)]] set i 0 let k 0 ask node 35 ;; here i use node 35 as an example. ;; node 35 is connected to node 34, 36, 20 and 50 [table:put netw (35) [0 1] ;; node need to search costs to travel to itself ;; putting constants is ok. while [i < j] [ask my-links [ask both-ends [if (who != 35) [set color blue ;; set temp ([linkspeed] of street 35 who) ;; here my real goal is to put this in stat of i. but i is easier than linkspeed. table:put netw (who) [ i 2 ] ] ] ] set i (i + 1)] ] ;; next node for later, no it is just repetition of the same. end I hope somebody knows what is going on... Kind regards, Chantal

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• What is the best approach for creating a Common Information Model?

  - by Kaiser Advisor

  Hi, I would like to know the best approach to create a Common Information Model. Just to be clear, I've also heard it referred to as a canonical information model, semantic information model, and master data model - As far as I can tell, they are all referring to the same concept. I've heard in the past that a combined "top-down" and "bottom-up" approach is best. This has the advantage of incorporating "Ivory tower" architects and developers - The work will meet somewhere in the middle and usually be both logical and practical. However, this involves bringing in a lot of people with different skill sets. I've also seen a couple of references to the Distributed Management Task Force, but I can't glean much on best practices in terms of CIM development. This is something I'm quite interested in getting some feedback on since having a strong CIM is a prerequisite to SOA. Thanks for your help! KA Update I've heard another strategy goes along with overall SOA implementation: Get the business involved, and seek executive sponsorship. This would be part of the "Top-down" effort.

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• How Can I Create Reports in a Custom C#.NET Windows Application? - General Question

  - by user311509

  Assume i have a custom Windows application written in C#. This application has only the following functionalists, add, edit, delete and view. For example, a user can add a sale, change sales record, delete a sale record or view the whole sales record. I need to add some reporting functionalists e.g. i want a user to print the sales of a certain customer from 2008 to 2009 into pdf, what all products a certain customer has purchased from us and so on. I will only include the basic common report requests that are usually needed in the office. Any other kind of reports that are requested inconsistently, i would do it manually from my side at the back end and send the results manually to the requester. What i would do is: If a user wants more info of a certain customer, a special window box appears for that customer. This window box will have different controls that allows user to request more info such as, print customer purchases from ..... to ..... (user chooses the dates) and user will view results in pdf or so. Of course, at the back scene i will write an appropriate SQL Query with parameters that meets a certain function. Is this how it should be done? I have heard about SQL Reporting, i don't know anything about it yet. I will check it out. Anyhow, your suggestions won't harm. I'm still a student, so i don't have practical experience yet. I hope my question is clear enough. Thank you.

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• Screen capture doesn't work on MFC application in Vista

  - by David Thornley

  We've got some in-house applications built in MFC, with OpenGL drawing routines. They all use the same code to draw on the screen and either print the screen or save it to a JPEG file. Everything's been working fine in Windows XP, and I need to find a way to make them work on Vista. In three of our applications, everything works. In the remaining one, I can get the window border, title bar, menus, and task bar, but the interior never shows up. As I said, these applications use the exact same code to write to the screen and capture the window image, and the only difference I see that looks like it might be relevant is that the problem application uses the MFC multiple document interface, while the ones that work use the single document interface. Either the answer isn't on the net, or I'm worse at Googling than I thought. I asked on the MSDN forums, and the only practical suggestion I got was to use GDI+ rather than GDI, and that did nothing different. I have tried different things with every part of the code that captures and prints or save, given a pointer to the window, so apparently it's a matter of the window itself. I haven't rebuilt the offending application using SDI yet, and I really don't have any other ideas. Has anybody seen anything like this?

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• Which version of Grady Booch's OOA/D book should I buy?

  - by jackj

  Grady Booch's "Object-Oriented Analysis and Design with Applications" is available brand new in both the 2nd edition (1993) and the 3rd edition (2007), while many used copies of both editions are available. Here are my concerns: 1) The 2nd edition uses C++: given that I just finished reading my first two C++ books (Accelerated C++ and C++ Primer) I guess practical tips can only help, so the 2nd edition is probably best (I think the 3rd edition has absolutely no code). On the other hand, the C++ books I read insist on the importance of using standard C++, whereas Booch's 2nd edition was published before the 1998 standard. 2) The 2nd edition is shorter (608 pages vs. 720) so, I guess, it will be slightly easier to get through. 3) The 3rd edition uses UML 2.0, whereas the 2nd edition is pre-UML. Some reviews say that the notation in the 2nd edition is close enough to UML, so it doesn't matter, but I don't know if I should be worrying about this or not. 4) The 2nd edition is available in good-shape used copies for considerably less than what the 3rd one goes for. Given all the above factors, do you think I should buy the 2nd or the 3rd edition? Recommendations on other books are also welcome but I would prefer it if whoever answers has read at least one of the versions of Booch's book (preferably both!). I have already bought but not read GoF and Riel's books. I also know that I should practice a lot with real-life code. Thanks.

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• OO vs Simplicity when it comes to user interaction

  - by Oetzi

  Firstly, sorry if this question is rather vague but it's something I'd really like an answer to. As a project over summer while I have some downtime from Uni I am going to build a monopoly game. This question is more about the general idea of the problem however, rather than the specific task I'm trying to carry out. I decided to build this with a bottom up approach, creating just movement around a forty space board and then moving on to interaction with spaces. I realised that I was quite unsure of the best way of proceeding with this and I am torn between two design ideas: Giving every space its own object, all sub-classes of a Space object so the interaction can be defined by the space object itself. I could do this by implementing different land() methods for each type of space. Only giving the Properties and Utilities (as each property has unique features) objects and creating methods for dealing with the buying/renting etc in the main class of the program (or Board as I'm calling it). Spaces like go and super tax could be implemented by a small set of conditionals checking to see if player is on a special space. Option 1 is obviously the OO (and I feel the correct) way of doing things but I'd like to only have to handle user interaction from the programs main class. In other words, I don't want the space objects to be interacting with the player. Why? Errr. A lot of the coding I've done thus far has had this simplicity but I'm not sure if this is a pipe dream or not for larger projects. Should I really be handling user interaction in an entirely separate class? As you can see I am quite confused about this situation. Is there some way round this? And, does anyone have any advice on practical OO design that could help in general?

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• Cobol web development/hosting resources

  - by felixm

  Hello, I'm employed at a fairly big company here in Germany and got the job to create the main website for it which will feature: Static contents; Information and Presentations An employee area (around 6000 employees) featuring various things from calenders, job descriptions, some sort of groups Too many other dynamic things I can't list here I have decided to use COBOL for the job, it may be very underrated but it is a very powerful language, especially for business apps and, as my co-workers say, web (2.0) development too. I also need to use COBOL because all the backend and transactions system of the company is programmed in it (some small parts were programmed in LISP too, idk exactly why). I also have received an API that makes it possible to use COBOL with MySQL easily. This is a big project and it will probably take more than 2 months programming it. What do I have to expect when building a huge web app in COBOL? Are there web frameworks for COBOL available? Some sort of MVC? Are there any good resources for practical web-development with COBOL? Thanks in advance

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• Delphi : Handling the fact that Strings are not Objects

  - by awmross

  I am trying to write a function that takes any TList and returns a String representation of all the elements of the TList. I tried a function like so function ListToString(list:TList<TObject>):String; This works fine, except you can't pass a TList to it. E2010 Incompatible types: 'TList<System.TObject>' and 'TList<System.string>' In Delphi, a String is not an Object. To solve this, I've written a second function: function StringListToString(list:TList<string>):String; Is this the only solution? Are there other ways to treat a String as more 'object-like'? In a similar vein, I also wanted to write an 'equals' function to compare two TLists. Again I run into the same problem function AreListsEqual(list1:TList<TObject>; list2:TList<TObject>):boolean; Is there any way to write this function (perhaps using generics?) so it can also handle a TList? Are there any other tricks or 'best practises' I should know about when trying to create code that handles both Strings and Objects? Or do I just create two versions of every function? Can generics help? I am from a Java background but now work in Delphi. It seems they are lately adding a lot of things to Delphi from the Java world (or perhaps the C# world, which copied them from Java). Like adding equals() and hashcode() to TObject, and creating a generic Collections framework etc. I'm wondering if these additions are very practical if you can't use Strings with them.

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• How to access hidden template in unnamed namespace?

  - by Johannes Schaub - litb

  Here is a tricky situation, and i wonder what ways there are to solve it namespace { template <class T> struct Template { /* ... */ }; } typedef Template<int> Template; Sadly, the Template typedef interferes with the Template template in the unnamed namespace. When you try to do Template<float> in the global scope, the compiler raises an ambiguity error between the template name and the typedef name. You don't have control over either the template name or the typedef-name. Now I want to know whether it is possible to: Create an object of the typedefed type Template (i.e Template<int>) in the global namespace. Create an object of the type Template<float> in the global namespace. You are not allowed to add anything to the unnamed namespace. Everything should be done in the global namespace. This is out of curiosity because i was wondering what tricks there are for solving such an ambiguity. It's not a practical problem i hit during daily programming.

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• How to I pass parameters to Ruby/Python scripts from inside PHP?

  - by Roger

  Hi, everybody. I need to turn HTML into equivalent Markdown-structured text. From what I could discover, I have only two good choices: Python: Aaron Swartz's html2text.py Ruby: Singpolyma's html2markdown.rb As I am programming in PHP, I need to pass the HTML code, call the Ruby/Python Script and receive the output back. I started creating a simple test just to know if my server was configured to run both languages. PHP code: echo exec('./hi.rb'); Ruby code: #!/usr/bin/ruby puts "Hello World!" It worked fine and I am ready to go to the next step. Unfortunately, all I know is that the function is Ruby works like this: HTML2Markdown.new('<h1>HTMLcode</h1>').to_s I don't know how to make PHP pass the string (with the HTML code) to Ruby nor how to make the ruby script receive the variable and pass it back to PHP (after have parsed it into Markdown). Believe it or not: I know less of Python. A folk made a similar question here ("how to call ruby script from php?") but with no practical information to my case. Any help would be a joy - thanks. Rogério Madureira. atipico.com.br

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• Decoupling the view, presentation and ASP.NET Web Forms

  - by John Leidegren

  I have an ASP.NET Web Forms page which the presenter needs to populate with controls. This interaction is somewhat sensitive to the page-life cycle and I was wondering if there's a trick to it, that I don't know about. I wanna be practical about the whole thing but not compromise testability. Currently I have this: public interface ISomeContract { void InstantiateIn(System.Web.UI.Control container); } This contract has a dependency on System.Web.UI.Control and I need that to be able to do things with the ASP.NET Web Forms programming model. But neither the view nor the presenter may have knowledge about ASP.NET server controls. How do I get around this? How can I work with the ASP.NET Web Forms programming model in my concrete views without taking a System.Web.UI.Control dependency in my contract assemblies? To clarify things a bit, this type of interface is all about UI composition (using MEF). It's known through-out the framework but it's really only called from within the concrete view. The concrete view is still the only thing that knows about ASP.NET Web Forms. However those public methods that say InstantiateIn(System.Web.UI.Control) exists in my contract assemblies and that implies a dependency on ASP.NET Web Forms. I've been thinking about some double dispatch mechanism or even visitor pattern to try and work around this.

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• Creating futures using Apple's GCD

  - by jer

  I'm working on a library which implements the actor model on top of Grand Central Dispatch (specifically the C level API libdispatch). Basically a brief overview of my system is as such: Communication happens between actors using messages Multicast communication only (one actor to many actors) Senders and receivers are decoupled from one another using a blackboard where messages are pushed to. Messages are sent in the default queue asynchronously using dispatch_group_async() once a message gets pushed onto the blackboard. I'm trying to implement futures in the language right now, so I've created a new type which holds some information: A group of its own The value being 'returned' However, I have a problem since dispatch_block_t is of type void (^)(void) so it doesn't return anything. So my idea of in my future_new() function of setting up another group which can be used to execute a block returning a result, which I can store in my "value" member in my future_t structure, isn't going to work. The rest of the futures implementation is very clear, except it all depends on being able to get the value into the future back from the actor, acting on the message. When using the library, it would greatly reduce its usefulness if I had to ask users (and myself) to be aware when futures were going to be used by other parts of the system—It just isn't practical. I'm wondering if anyone can think of a way around this?

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• A good solution for displaying galleries with lytebox and php

  - by Johann

  Hello I have thought for a while over an issue with the loading of images on a website-solution that I have programmed (For fun and the experience) The programming language used is PHP with MYSQL as the database language It also uses javascript, but not extensively I have recently realized that the engine I programmed, while it has it's smart solutions also carry a lot of flaws and redundant code. I have therefore decided to make a new one, now incorporating what I know, but didn't when I started the previous project. For the new system, there will be an option to add galleries to a site, and upload images to it. I have used the javascript image viewer Lytebox before. The screen goes dark and an image appears with a "Previous" and "next" button to view the other images. The problem is that I used groups with lytebox and the images themselves, resized as thumbs. This causes lytebox to work only when all the images have loaded. If you click a link before that, the image is shown as if you right click and choose "Show image" Information about these images is parsed from a database using a while statement with a counter that goes from 0 to sizeof() I'm thinking it probably isn't a good idea to have the images as the thumbs, even if you restrict the upload size. Likewise, adding thumbs at upload also seems like a hassle. It would be practical if the thumbs didn't show up before they were fully loaded. Has anyone got any good tips. Any help would be appreciated. Johann

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• Add less than integer variable to string search

  - by user1691832

  I'm scanning a text document for certain installed programs on a computer and looking for an easy way to include a greater or less than variable in the string I'm scanning for. Here is a very ugly and cumbersome example of what I'm using currently and while it works as a temporary fix, isn't practical or sustainable. If CheckBox2.Checked Then sReader.Close() If text.Contains("Adobe Flash Player 11 Plugin") And text.Contains("Adobe Flash Player 11 ActiveX") Then Else If text.Contains("Adobe Flash Player 12 Plugin") And text.Contains("Adobe Flash Player 12 ActiveX") Then Else If text.Contains("Adobe Flash Player 13 Plugin") And text.Contains("Adobe Flash Player 13 ActiveX") Then Else '(Goes ahead and does a silent install of the missing or outdated program) So far I've run into this problem with both Adobe Flash and Java RTE and am certain to run into it with future programs. Essentially I need to scan for "Adobe Flash Player (Any number less than 11) Plugin" , "Adobe Flash Player (Any number less than 11) ActiveX" , "Java (number less than 9) Update (any number)". I'm sure whatever solution is offered can likely be adapted to similar programs I'm likely to encounter later. Thanks ----- Edit ----- I've since tried the following code but it always returns the "Found" messagebox, even when no version of adobe flash is present in the file it is scanning. If CheckBox2.Checked Then sReader.Close() Dim options As RegexOptions = RegexOptions.None Dim regex As Regex = New Regex("Adobe Flash Player (?<version>\d+) (Plugin|ActiveX)", options) Dim input As String = "Adobe Flash Player 11 Plugin" ' Get match Dim match As Match = regex.Match(input) Dim version As String = match.Groups("version").Value If (match.Success) Then MessageBox.Show("Version 11 or higher found, skipping install") Else MessageBox.Show("Version 11 or higher not found, installing Version 11")

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• Is the Java classpath final after JVM startup?

  - by Jens

  Hi, I have read a lot about the Java class loading process lately. Often I came across texts that claimed that it is not possible to add classes to the classpath during runtime and load them without class loader hackery (URLClassLoaders etc.) As far as I know classes are loaded dynamically. That means their bytecode representation is only loaded and transformed to a java.lang.Class object when needed. So shouldn't it be possible to add a JAR or *.class file to the classpath after the JVM started and load those classes, provided they haven't been loaded yet? (To be clear: In this case the classpath is simple folder on the filesystem. "Adding a JAR or *.class file" simply means dropping them in this folder.) And if not, does that mean that the classpath is searched on JVM startup and all fully qualified names of the found classes are cached in an internal "list"? It would be nice of you if you could point me to some sources in your answers. Preferably the offical SUN documentation: Sun JVM Spec. I have read the spec but could not find anything about the classpath and if it's finalized on JVM startup. P.s. This is a theoretical question. I just want to know if it is possible. There is nothing practical I want to achieve. There is just my thirst for knowledge :)

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• named_scope + average is causing the table to be specified more then once in the sql query run on po

  - by hadees

  I have a named scopes like so... named_scope :gender, lambda { |gender| { :joins => {:survey_session => :profile }, :conditions => { :survey_sessions => { :profiles => { :gender => gender } } } } } and when I call it everything works fine. I also have this average method I call... Answer.average(:rating, :include => {:survey_session => :profile}, :group => "profiles.career") which also works fine if I call it like that. However if I were to call it like so... Answer.gender('m').average(:rating, :include => {:survey_session => :profile}, :group => "profiles.career") I get... ActiveRecord::StatementInvalid: PGError: ERROR: table name "profiles" specified more than once : SELECT avg("answers".rating) AS avg_rating, profiles.career AS profiles_career FROM "answers" LEFT OUTER JOIN "survey_sessions" survey_sessions_answers ON "survey_sessions_answers".id = "answers".survey_session_id LEFT OUTER JOIN "profiles" ON "profiles".id = "survey_sessions_answers".profile_id INNER JOIN "survey_sessions" ON "survey_sessions".id = "answers".survey_session_id INNER JOIN "profiles" ON "profiles".id = "survey_sessions".profile_id WHERE ("profiles"."gender" = E'm') GROUP BY profiles.career Which is a little hard to read but says I'm including the table profiles twice. If I were to just remove the include from average it works but it isn't really practical because average is actually being called inside a method which gets passed the scoped. So there is some times gender or average might get called with out each other and if either was missing the profile include it wouldn't work. So either I need to know how to fix this apparent bug in Rails or figure out a way to know what scopes were applied to a ActiveRecord::NamedScope::Scope object so that I could check to see if they have been applied and if not add the include for average.

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• Creating a global variable on the fly. [PHP ENCRYPTION]

  - by stormdrain

  Is there a way to dynamically create constant variables on the fly? The idea is that upon logging into the system, a user would be asked to upload a small text file that would be fread, and assigned to a var that would be accessible throughout the system. If this is possible, just to be clear, would this variable then only be accessible to that user and only while the session is alive? Security being the main concern here, would it be more practical to store the var in a session variable? The plan: Data in the db will be encrypted via mcrypt, and the key will be stored on USB thumbdrives. The user will insert the thumbdrive when going to access the system. Upon logging in, the app will prompt the user to upload the key. They will navigate to the thumbdrive and key. Via fopen and fread, the key will be assigned to a global var which will then allow access to encrypted data, and will be used to encrypt new info being entered to the db. When the user logs out, or session times out, the global var will become empty. Thanks!

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• GSM Cell Towers Location & Triangulation Algorithm (Similar to OpenCellID / Skyhook / Google's MyLocation)

  - by ranabra

  Hi all, assuming I have a Fingerprint DB of Cell towers. The data (including Long. & Lat. CellID, signal strength, etc) is achieved by 'wardriving', similar to OpenCellID.org. I would like to be able to get the location of the client mobile phone without GPS (similar to OpenCellID / Skyhook Wireless/ Google's 'MyLocation'), which sends me info on the Cell towers it "sees" at the moment: the Cell tower connected to, and another 6 neighboring cell towers (assuming GSM). I have read and Googled it for a long time and came across several effective theories, such as using SQL 2008 Spatial capabilities, or using an euclidean algorithm, or Markov Model. However, I am lacking a practical solution, preferably in C# or using SQL 2008 :) The location calculation will be done on the server and not on the client mobile phone. the phone's single job is to send via HTTP/GPRS, the tower it's connected to and other neighboring cell towers. Any input is appreciated, I have read so much and so far haven't really advanced much. Thanx

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