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• What is an elegant way to set up a leiningen project that requires different dependencies based on the build platform?

  - by Savanni D'Gerinel

  In order to do some multi-platform GUI development, I have just switched from GTK + Clojure (because it looks like the Java bindings for GTK never got ported to Windows) to SWT + Clojure. So far, so good in that I have gotten an uberjar built for Linux. The catch, though, is that I want to build an uberjar for Windows and I am trying to figure out a clean way to manage the project.clj file. At first, I thought I would set the classpath to point to the SWT libraries and then build the uberjar. This would require that I set a classpath to the SWT libraries before running the jar, but I would likely need a launcher script, anyway. However, leiningen seems to ignore the classpath in this instance because it always reports that Currently, project.clj looks like this for me: (defproject alyra.mana-punk/character "1.0.0-SNAPSHOT" :description "FIXME: write" :dependencies [[org.clojure/clojure "1.2.0"] [org.clojure/clojure-contrib "1.2.0"] [org.eclipse/swt-gtk-linux-x86 "3.5.2"]] :main alyra.mana-punk.character.core) The relevant line is the org.eclipse/swt-gtk-linux-x86 line. If I want to make an uberjar for Windows, I have to depend on org.eclipse/swt-win32-win32-x86, and another one for x86-64, and so on and so forth. My current solution is to simply create a separate branch for each build environment with a different project.clj. This seems kinda like using a semi to deliver a single gallon of milk, but I am using bazaar for version control, so branching and repeated integrations are easy. Maybe the better way is to have a project.linux.clj, project.win32.clj, etc, but I do not see any way to tell leiningen which project descriptor to use. What are other (preferably more elegant) ways to set up such an environment?

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• Methods to Analyze Sell Orders (in a video game)

  - by Travis

  I'm building a market manager for EVE, but this problem should be solvable without any prior knowledge of the game. Basically, sell orders in EVE look like this: All I'm really concerned with is picking a good price. The numbers the program would pick are sent out to our production team so they can buy the items to build things. Just like in a real market, the numbers we send off need to reflect the cheapest price that still offers a good quantity. Also, available quantities change over time, so we can't just pick the lowest listed price. For example, in the screencap above, we would set the sell price between 2,800.00 ISK and 3,000.00 ISK, even if only 500 units were needed. Even though the cheapest order would fit the quantity, it would probably quickly disappear. It would be better to set the price a tad higher so we don't underpay the production people. The Question: It's easy enough to figure prices out just by looking at the data, but I can't figure out how to have a program [java] do it. Different items sell with much less or more quantities (i.e. 3 or 300 or 3000 items) so the program has to be able to modify itself based on the offerings. I don't really want code as much as I do a way to think this through. Thanks in advance.

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• Alternative to using c:out to prevent XSS

  - by lynxforest

  I'm working on preventing cross site scripting (XSS) in a Java, Spring based, Web application. I have already implemented a servlet filter similar to this example http://greatwebguy.com/programming/java/simple-cross-site-scripting-xss-servlet-filter/ which sanitizes all the input into the application. As an extra security measure I would like to also sanitize all output of the application in all JSPs. I have done some research to see how this could be done and found two complementary options. One of them is the use of Spring's defaultHtmlEscape attribute. This was very easy to implement (a few lines in web.xml), and it works great when your output is going through one of spring's tags (ie: message, or form tags). The other option I have found is to not directly use EL expressions such as ${...} and instead use <c:out value="${...}" /> That second approach works perfectly, however due to the size of the application I am working on (200+ JSP files). It is a very cumbersome task to have to replace all inappropriate uses of EL expressions with the c:out tag. Also it would become a cumbersome task in the future to make sure all developers stick to this convention of using the c:out tag (not to mention, how much more unreadable the code would be). Is there alternative way to escape the output of EL expressions that would require fewer code modifications? Thank you in advance.

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• Passing a parameter in a Report's Open Event to a parameter query (Access 2007)

  - by JPM

  Hi there, I would like to know if there is a way to set the parameters in an Access 2007 query using VBA. I am new to using VBA in Access, and I have been tasked with adding a little piece of functionality to an existing app. The issue I am having is that the same report can be called in two different places in the application. The first being on a command button on a data entry form, the other from a switchboard button. The report itself is based on a parameter query that has requires the user to enter a Supplier ID. The user would like to not have to enter the Supplier ID on the data entry form (since the form displays the Supplier ID already), but from the switchboard, they would like to be prompted to enter a Supplier ID. Where I am stuck is how to call the report's query (in the report's open event) and pass the SupplierID from the form as the parameter. I have been trying for a while, and I can't get anything to work correctly. Here is my code so far, but I am obviously stumped. Private Sub Report_Open(Cancel As Integer) Dim intSupplierCode As Integer 'Check to see if the data entry form is open If CurrentProject.AllForms("frmExample").IsLoaded = True Then 'Retrieve the SupplierID from the data entry form intSupplierCode = Forms![frmExample]![SupplierID] 'Call the parameter query passing the SupplierID???? DoCmd.OpenQuery "qryParams" Else 'Execute the parameter query as normal DoCmd.OpenQuery "qryParams"????? End If End Sub I've tried Me.SupplierID = intSupplierCode, and although it compiles, it bombs when I run it. And here is my SQL code for the parameter query: PARAMETERS [Enter Supplier] Long; SELECT Suppliers.SupplierID, Suppliers.CompanyName, Suppliers.ContactName, Suppliers.ContactTitle FROM Suppliers WHERE (((Suppliers.SupplierID)=[Enter Supplier])); I know there are ways around this problem (and probably an easy way as well) but like I said, my lack of experience using Access and VBA makes things difficult. If any of you could help, that would be great!

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• Git from localhost to remotehost with a team of three

  - by Mark McDonnell

  Hi, I'm completely new to Git. I've only just worked out how to use Github in a basic way (e.g. push my local file changes to Github - so I've not done 'pulling' down of content from Github and 'merging' it into my localhost version or anything like that). I had a look over at this existing question - Git: localhost remote development remote production - but I think it may have been a bit advanced for me at this stage as I didn't quite understand the terminology that most of the people were using. What I would like to achieve is to have a local server set-up that my team of developers can all 'push' to/'pull' from etc. And then have that local server upload any updated files automatically to our web server so we could see the updates live in the browser. I'm happy to get a server set-up in the office running Mac OSX Server and then installing Git on it and then getting the devs to write a shell script to push to the remote server but only if it was fairly easy for the devs local git to push to this new local server. I'm not a network engineer so I don't know what would need to be set-up for that to work, I know obviously we could set-up the server to be accessible via a local ip address like 192.168.0.xxx but not sure how that works with pushing to a git repository on that server? Would that literally be something like doing this on my local machine: git remote add MyGitFile git://192.168.0.xxx/MyGitFile.git ? Any ideas or advice you can give to a total Git newbie trying to help his team get a better work flow. Kind regards, Mark

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• How can I diff against a revision of a single file using only the default Git GUI tools?

  - by Rich

  I want to view the history of a single file, and then compare a single revision from that history against the current version. On the command line, this is easy: Run: git log -- <filename> Locate the version you want to compare, Run: git diff <commitid> -- <filename> But how can this be done using only the default Git gui tools, git gui and gitk? I know of two methods using gitk, but they're both horribly clunky: Either: Select the New View option from the View menu, Type in the full path to your file into the box labelled Enter files and directories to include, one per line, Locate the version you want to compare by looking at the highlighted items in the top pane, and click on it to select it, Right-click on the current version and select Diff selected - this, Or: Select Tree in the bottom right-hand pane, Locate the file you want to look at, right-click on it, and select Highlight this only, Locate the version you want to compare by looking at the highlighted items in the top pane, and click on it to select it, Right-click on the current version and select Diff selected - this, Click on the file in the bottom right-hand pane to jump to it in the diff output, or scroll manually. Is a better method than this?

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• Android - Basic CRUD (REST/RPC client) to remote server

  - by bsreekanth

  There are lot of discussion about REST client implementation in android, based on the talk at GoogleIO 2010, by Virgil Dobjanschi. My requirement may not necessarily involved, as I have some freedom to choose the configuration. I only target tablets configuration changes can be prevented if no other easy way (fix at Landscape mode etc) I am trying to achieve. Basic CRUD operation to my server (JSON RPC/ REST). Basically mimic an ajax request from android app (no webview, need native app) Based on the above mentioned talk, and some reading I see these options. Implement any of the 3 mentioned in the Google IO talk Especially, the last pattern may be more suitable as I don't care much of caching. But not sure how "real time" is sync implementation. Use HTTP request in AsyncTask. Simplest, but need to avoid re-sending request during change in device configuration (orientation change etc). Even if I fix at one orientation, recreation of activity still happens. So need to handle it elegantly. Use service to handle http request. So far, it say use service for long ruiing request. Not sure whether it is a good approach for simple GET/POST/PUt requests. Please share your experience on what could be the best way.

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• data transmission between two sites

  - by SaMSa

  I'm use Asp.Net Mvc 4 www.hostname.com to my site from my report.hostname2.com send and receive data to move directly to that address by the string bi codebehind. querysstring not, because sending a very long string I mean rapor.coskunoglu.net/Pdf address to send string data to move directly to that address PDF of the screen to make it appear so. How can I do this? Thank you, take it easy. I'm sorry, my english is not good. EDIT: I want to use POST. sb - my StringBuilder. byte[] bytt = Encoding.UTF8.GetBytes(sb.ToString()); WebRequest wr = WebRequest.Create("http://report.hostname2.com/Pdf"); wr.ContentType = "application/x-www-form-urlencoded"; wr.ContentLength = bytt.Length; wr.Method = "POST"; Stream st = wr.GetRequestStream(); st.Write(bytt, 0, bytt.Length); st.Close(); After you send the POST I want to go to report.hostname2.com. Did you see this my job?

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• Bitwise operators and converting an int to 2 bytes and back again.

  - by aKiwi

  first time user, Hi guys! So hopefully someone can help.. My background is php so entering the word of lowend stuff like, char is bytes, which are bits.. which is binary values.. etc is taking some time to get the hang of ;) What im trying to do here is sent some values from an Ardunio board to openFrameWorks (both are c++). What this script currently does (and works well for one sensor i might add) when asked for the data to be sent is.. int value_01 = analogRead(0); // which outputs between 0-1024 unsigned char val1; unsigned char val2; //some Complicated bitshift operation val1 = value_01 &0xFF; val2 = (value_01 >> 8) &0xFF; //send both bytes Serial.print(val1, BYTE); Serial.print(val2, BYTE); Apparently this is the most reliable way of getting the data across.. So now that it is send via serial port, the bytes are added to a char string and converted back by.. int num = ( (unsigned char)bytesReadString[1] << 8 | (unsigned char)bytesReadString[0] ); So to recap, im trying to get 4 sensors worth of data (which im assuming will be 8 of those serialprints?) and to have int num_01 - num_04... at the end of it all. Im assuming this (as with most things) might be quite easy for someone with experience in these concepts.. Any help would be greatly appreciated. Thanks

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• Is the REST support in Spring 3's MVC Framework production quality yet?

  - by glenjohnson

  Hi all, Since Spring 3 was released in December last year, I have been trying out the new REST features in the MVC framework for a small commercial project involving implementing a few RESTful Web Services which consume XML and return XML views using JiBX. I plan to use either Hibernate or JDBC Templates for the data persistence. As a Spring 2.0 developer, I have found Spring 3's (and 2.5's) new annotations way of doing things quite a paradigm shift and have personally found some of the new MVC annotation features difficult to get up to speed with for non-trivial applications - as such, I am often having to dig for information in forums and blogs that is not apparent from going through the reference guide or from the various Spring 3 REST examples on the web. For deadline-driven production quality and mission critical applications implementing a RESTful architecture, should I be holding off from Spring 3 and rather be using mature JSR 311 (JAX-RS) compliant frameworks like RESTlet or Jersey for the REST layer of my code (together with Spring 2 / 2.5 to tie things together)? I had no problems using RESTlet 1.x in a previous project and it was quite easy to get up to speed with (no magic tricks behind the scenes), but when starting my current project it initially looked like the new REST stuff in Spring 3's MVC Framework would make life easier. Do any of you out there have any advice to give on this? Does anyone know of any commercial / production-quality projects using, or having successfully delivered with, the new REST stuff in Spring 3's MVC Framework. Many thanks Glen

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• Weird character at start of json content type

  - by Nek

  Hi, I'm trying to return json content read from MySQL server. This is supposed to be easy but, there is a 'weird' character that keeps appearing at start of the content. I have two pages for returning content: kcb433.sytes.net/as/test.php?json=true&limit=6&input=d this test.php is from a script written by Timothy Groves, which converts an array to json output http://kcb433.sytes.net/k.php?k=4 this one is supposed to do the same I tried to validate it here jsonformatter.curiousconcept.com but just page 1 gets validated, page 2 says that it does not contain JSON data. If accessed directly both pages has no problems. Then what is the difference, why both don't get validated? Then I found this page jsonformat.com and tried the same thing. Page 1 was ok and page 2 wasn't but, surprisingly the data could be read. At a glance, {"a":"b"} may look good but there is a character in front. According to a hex editor online, this is the value of the string above (instead of 9 values, there are 10): -- 7B 22 61 22 3A 22 62 22 7D The code to echo json in page 2 is: header("Content-Type: application/json"); echo "{\"a\":\"b\"}";

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• URL protocol handler shell execute problem

  - by Chuck

  Hi, I'm working on a small hobby web site where I'm able to launch a local app with certain arguments based on links. Setting up a protocol wasn't difficult, as described in http://msdn.microsoft.com/en-us/library/aa767914(VS.85).aspx, but I have one dilemma: Let's say the protocol is: foo:127.0.0.1:1111, so a link like href="foo:127.0.0.1:1111" would launch an app like: bar.exe "%1". Since I don't have any control over bar.exe (if I had, then it would be no problem to just parse it, obviously), I need some help parsing %1. bar.exe will launch correctly if it's run as bar.exe 127.0.0.1:1111, but not if it's run as bar.exe foo:127.0.0.1:1111. So I guess my question is... is there ANY way to tell the registry to pass on not %1, but a trimmed %1? (Thinking in terms of regexp where you have match[0] = all of the matched, match[1] = first capture in the matched text). I can solve it by having a .bat instead of .exe, but as I would like to make it as easy as possible for the user to use, I would LOVE it if I could handle it all stricly in registry. Any help is greatly appreciated! Chuck

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• What makes good web form styling for business applications?

  - by ProfK

  Styling forms (form elements) is something that even Eric Meyer prefers to avoid. However, most business forms, and that is where styling is at issue; 'contact us' forms are easy to style, put window estate at a premium, with more 'document level' (e.g. invoice) fields, plus 'detail level' (e.g. invoice line) fields. Factors I often find at play are: At my minimum, at least two horizontally adjacent fieldsets are required. In applications vs. public web pages, fixed positioning vs fluid layout is often better. Quantity of content is important, vs. exaggerated readability. Users know the system, and cues etc. take a back seat. In light of factors like these, is there any available guidence for styling web form based applications? Are there any CSS or JavaScript frameworks that would make my quest to style these applications better than Visual Studios still pathetic 'Auto-format' (what drugs were those people on? I will never take them.)

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• Class design when working with dataset

  - by MC

  If you have to retrieve data from a database and bring this dataset to the client, and then allow the user to manipulate the data in various ways before updating the database again, what is a good class design for this if the data tables will not have a 1:1 relationship with the class objects? Here are some I came up with: Just manipulate the DataSet itself on the client and then send it back to the database as is. This will work though obviously the code will be very dirty and not well-structured. Same as #1, but wrap the dataset code around classes. What I mean is that you may have a class that takes a dataset or a datatable in its constructor, and then provides public methods and properties to simplify the code. Inside these methods and properties it will be reading or manipulating the dataset. To update the database afterwards will be easy because you already have the updated dataset. Get rid of the dataset entirely on the client, convert to objects, then convert back to a dataset when needing to update the database. Is there any good resources where I can find information on this?

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• What is the benefit of using ONLY OpenID authentication on a site?

  - by Peter

  From my experience with OpenID, I see a number of significant downsides: Adds a Single Point of Failure to the site It is not a failure that can be fixed by the site even if detected. If the OpenID provider is down for three days, what recourse does the site have to allow its users to login and access the information they own? Takes a user to another sites content and every time they logon to your site Even if the OpenID provider does not have an error, the user is re-directed to their site to login. The login page has content and links. So there is a chance a user will actually be drawn away from the site to go down the Internet rabbit hole. Why would I want to send my users to another company's website? [ Note: my provider no longer does this and seems to have fixed this problem (for now).] Adds a non-trivial amount of time to the signup To sign up with the site a new user is forced to read a new standard, chose a provider, and signup. Standards are something that the technical people should agree to in order to make a user experience frictionless. They are not something that should be thrust on the users. It is a Phisher's Dream OpenID is incredibly insecure and stealing the person's ID as they log in is trivially easy. [ taken from David Arno's Answer below ] For all of the downside, the one upside is to allow users to have fewer logins on the Internet. If a site has opt-in for OpenID then users who want that feature can use it. What I would like to understand is: What benefit does a site get for making OpenID mandatory?

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• Scale an image which is stored as a byte[] in Java

  - by Sergio del Amo

  I upload a file with a struts form. I have the image as a byte[] and I would like to scale it. FormFile file = (FormFile) dynaform.get("file"); byte[] fileData = file.getFileData(); fileData = scale(fileData,200,200); public byte[] scale(byte[] fileData, int width, int height) { // TODO } Anyone knows an easy function to do this? public byte[] scale(byte[] fileData, int width, int height) { ByteArrayInputStream in = new ByteArrayInputStream(fileData); try { BufferedImage img = ImageIO.read(in); if(height == 0) { height = (width * img.getHeight())/ img.getWidth(); } if(width == 0) { width = (height * img.getWidth())/ img.getHeight(); } Image scaledImage = img.getScaledInstance(width, height, Image.SCALE_SMOOTH); BufferedImage imageBuff = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); imageBuff.getGraphics().drawImage(scaledImage, 0, 0, new Color(0,0,0), null); ByteArrayOutputStream buffer = new ByteArrayOutputStream(); ImageIO.write(imageBuff, "jpg", buffer); return buffer.toByteArray(); } catch (IOException e) { throw new ApplicationException("IOException in scale"); } } If you run out of Java Heap Space in tomcat as I did, increase the heap space which is used by tomcat. In case you use the tomcat plugin for Eclipse, next should apply: In Eclipse, choose Window Preferences Tomcat JVM Settings Add the following to the JVM Parameters section -Xms256m -Xmx512m

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• Building a custom Linux Live CD

  - by Mike Heinz

  Can anyone point me to a good tutorial on creating a bootable Linux CD from scratch? I need help with a fairly specialized problem: my firm sells an expansion card that requires custom firmware. Currently we use an extremely old live CD image of RH7.2 that we update with current firmware. Manufacturing puts the cards in a machine, boots off the CD, the CD writes the firmware, they power off and pull the cards. Because of this cycle, it's essential that the CD boot and shut down as quickly as possible. The problem is that with the next generation of cards, I have to update the CD to a 2.6 kernel. It's easy enough to acquire a pre-existing live CD - but those all are designed for showing off Linux on the desktop - which means they take forever to boot. Can anyone fix me up with a current How-To? Update: So, just as a final update for anyone reading this later - the tool I ended up using was "livecd-creator". My reason for choosing this tool was that it is available for RedHat-based distributions like CentOs, Fedora and RHEL - which are all distributions that my company supports already. In addition, while the project is very poorly documented it is extremely customizable. I was able to create a minimal LiveCD and edit the boot sequence so that it booted directly into the firmware updater instead of a bash shell. The whole job would have only taken an hour or two if there had been a README explaining the configuration file!

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• Usage Rails 3.0 beta 3 without ActiveRecord ORM

  - by Anton

  Hi everybody! Just installed Rails 3.0 beta 3 in Windows 7. And started playing with some easy examples class SignupController < ApplicationController def index @user = User.new(params[:user]) if method.post? and @user.save redirect_to :root end end end class User def initialize(params = {}) @email = params[:email] @passw = params[:password] end def save end end <div align="center"> <% form_for :user do |form| %> <%= form.label :email %> <%= form.text_field :email %><br /> <%= form.label :password %> <%= form.text_field :password %><br /> <%= form.submit :Register! %> <% end %> </div> When I go to /signup I'm getting this error ArgumentError in SignupController#index wrong number of arguments(0 for 1) Is there a problem with constructor or what's wrong?Please, need your help!

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• Java/Groovy File IO Replacing an Image File with it's own Contents - Why Does This Work?

  - by jboyd

  I have some JPG files that need to be replaced at runtime with a JFIF standardized version of themselves (we are using a vendor that gives us JPG that do not have proper headers so they don't work in certain applications)... I am able to create a new file from the existing image, then get a buffered image from that file and write the contents right back into the file without having to delete it and it works... imageSrcFolder.eachFileMatch ( ~/.*\.jpg/, { BufferedImage bi = ImageIO.read( it ) ImageIO.write( bi, "jpg", it ) }); The question I have is why? Why doesn't the file end up doubled in size? Why don't I have to delete it first? Why am I able to take a file object to an existing file and then treat it as if it were a brand new one? It seems that what I consider to be a "file" is not what the File object in java actually is, or else this wouldn't work at all. My code does exactly what I want it to do, but I'm not convinced it always will... it just seems way too easy

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• read the currency format

  - by user485783

  perhaps for some people this is easy, but I want to learn There are 2 currency formats: first currency format is 1,123,123.12 and this format may be like $1,123,123.12 or 1,123,123.12€ and second currency format is 1.123.123,12 and this may be such $1.123.123,12 or 1.123.123,12€ so the difference is the placement of dots and commas The above format will be $this->value('one of the currency format insert here'); e.g. $this->value('$1,123,123.12'); or $this->value('1.123.123,12€'); that I want to know is the code if (first currency format) {use blah .. blah ..} elseif (second currency format) {use blah .. blah ..} else {/ / unsupported format} so how the code to identify whether the entry is input the first currency format or second currency format? thanks for the your pointers and ideas. UPDATED: I apologize for mistake in giving examples When I tried to test the code I have a little confused because it seems not working then I changed my prevoious parts, so that $value['amount'] it may be use first currency format 1,123,123.12 and this format may be like $1,123,123.12 or 1,123,123.12€ and second currency format 1.123.123,12 and this may be such $1.123.123,12 or 1.123.123,12€ then the value['amount'] will identify first with code like the following conditional class curr_format { private bla...bla..1 private bla...bla..2 var etc.. public function curr_format ($bla...,$and_bla..) { //then make conditional is here if (first currency format) {//use blah .. blah ..} elseif (second currency format) {//use blah .. blah ..} else {/ / unsupported format} //another codes.. at the end output as look like: $identify = new curr_format(); echo $identify->curr_format($value['amount'],$else_statement);

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• What's the next steps for moving from appengine to full django?

  - by tomcritchlow

  Hey guys, I'm super new to programming and I've been using appengine to help me learn python and general coding. I'm getting better quickly and I'm loving it all the way :) Appengine was awesome for allowing me to just dive into writing my app and getting something live that works (see http://www.7bks.com/). But I'm realising that the longer I continue to learn on appengine the more I'm constraining myself and locking myself into a single system. I'd like to move to developing on full django (since django looks super cool!). What are my next steps? To give you a feel for my level of knowledge: I'm not a unix user I'm not familiar with command line controls (I still use appengine/python completely via the appengine SDK) I've never programmed in anything other than python, anywhere other than appengine I know the word SQL, but don't know what MySQL is really or how to use it. So, specifically: What are the skills I need to learn to get up and running with full django/python? If I'm going to host somewhere else I suppose I'll need to learn some sysadmin type skills (maybe even unix?). Is there anywhere that offers easy hosting (like appengine) but that supports django? I hear such great things about heroku I'm considering switching to RoR and going there I appreciate that I'm likely not quite ready to move away from appengine just yet but I'm a fiercely passionate learner (http://www.7bks.com/blog/179001) and would love it if I knew all the steps I needed to learn so I could set about learning them. At the moment, I don't even know what the steps are I need to learn! Thank you very much. Sorry this isn't a specific programming question but I've looked around and haven't found a good how-to for someone of my level of experience and I think others would appreciate a good roadmap for the things we need to learn to get up and running. Thanks, Tom PS - if anyone is in London and fancies showing me the ropes in person that would be super awesome :)

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• Handling user interface in a multi-threaded application (or being forced to have a UI-only main thre

  - by Patrick

  In my application, I have a 'logging' window, which shows all the logging, warnings, errors of the application. Last year my application was still single-threaded so this worked [quite] good. Now I am introducing multithreading. I quickly noticed that it's not a good idea to update the logging window from different threads. Reading some articles on keeping the UI in the main thread, I made a communication buffer, in which the other threads are adding their logging messages, and from which the main thread takes the messages and shows them in the logging window (this is done in the message loop). Now, in a part of my application, the memory usage increases dramatically, because the separate threads are generating lots of logging messages, and the main thread cannot empty the communication buffer quickly enough. After the while the memory decreases again (if the other threads have finished their work and the main thread gradually empties the communication buffer). I solved this problem by having a maximum size on the communication buffer, but then I run into a problem in the following situation: the main thread has to perform a complex action the main thread takes some parts of the action and let's separate threads execute this while the seperate threads are executing their logic, the main thread processes the results from the other threads and continues with its work if the other threads are finished Problem is that in this situation, if the other threads perform logging, there is no UI-message loop, and so the communication buffer is filled, but not emptied. I see two solutions in solving this problem: require the main thread to do regular polling of the communication buffer only performing user interface logic in the main thread (no other logic) I think the second solution seems the best, but this may not that easy to introduce in a big application (in my case it performs mathematical simulations). Are there any other solutions or tips? Or is one of the two proposed the best, easiest, most-pragmatic solution? Thanks, Patrick

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• Modifying C# dictionary value

  - by minjang

  I'm a C++ expert, but not at all for C#. I created a Dictionary<string, STATS>, where STATS is a simple struct. Once I built the dictionary with initial string and STATS pairs, I want to modify the dictionary's STATS value. In C++, it's very clear: Dictionary<string, STATS*> benchmarks; Initialize it... STATS* stats = benchmarks[item.Key]; // Touch stats directly However, I tried like this in C#: Dictionary<string, STATS> benchmarks = new Dictionary<string, STATS>(); // Initialize benchmarks with a bunch of STATS foreach (var item in _data) benchmarks.Add(item.app_name, item); foreach (KeyValuePair<string, STATS> item in benchmarks) { // I want to modify STATS value inside of benchmarks dictionary. STATS stat_item = benchmarks[item.Key]; ParseOutputFile("foo", ref stat_item); // But, not modified in benchmarks... stat_item is just a copy. } This is a really novice problem, but wasn't easy to find an answer. EDIT: I also tried like the following: STATS stat_item = benchmarks[item.Key]; ParseOutputFile(file_name, ref stat_item); benchmarks[item.Key] = stat_item; However, I got the exception since such action invalidates Dictionary: Unhandled Exception: System.InvalidOperationException: Collection was modified; enumeration operation may not execute. at System.ThrowHelper.ThrowInvalidOperationException(ExceptionResource resource) at System.Collections.Generic.Dictionary`2.Enumerator.MoveNext() at helper.Program.Main(String[] args) in D:\dev\\helper\Program.cs:line 75

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• Implementation of MVC with SQLite and NSURLConnection, use cases?

  - by user324723

  I'm interested in knowing how others have implemented/designed database & web services in their iphone app and how they simplified it for the entire application. My application is dependent on these services and I can't figure out a efficient way to use them together due to the (semi)complexity of my requirements. My past attempts on combining them haven't been completely successful or at least optimal in my mind. I'm building a database driven iphone app that uses a relational database in sqlite and consumes web services based on missing content or user interaction. Like this hasn't been done before...right? Since I am using a relational database - any web services consumed requires normalization, parsing the result and persisting it to the database before it can be displayed in a table view controller. The applications UI consists of nested(nav controller) table views where a user can select a cell and be taken to the next table view where it attempts to populate the table views data source from the database. If nothing exists in the database then it will send a request via web services to download its content, thus download - parse - persist - query - display. Since the user has the ability to request a refresh of this data it still requires the same process. Quickly describing what I've implemented and tried to run with - 1st attempt - Used a singleton web service class that handled sending web service requests, parsing the result and returning it to the table view controller via delegate protocols. Once the controller received that data it would then be responsible for persisting it to the database and re-returning the result. I didn't like the idea of only preventing the case where the app delegate selector doesn't exists(released) causing the app to crash. 2nd attempt - Used NSNotificationCenter for easy access to both database and web services but later realized it was more complex due to adding and removing observers per view(which isn't advised anyways).

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• Synchronizing one or more databases with a master database - Foreign keys

  - by Ikke

  I'm using Google Gears to be able to use an application offline (I know Gears is deprecated). The problem I am facing is the synchronization with the database on the server. The specific problem is the primary keys or more exactly, the foreign keys. When sending the information to the server, I could easily ignore the primary keys, and generate new ones. But then how would I know what the relations are. I had one sollution in mind, bet the I would need to save all the pk for every client. What is the best way to synchronize multiple client with one server db. Edit: I've been thinking about it, and I guess seqential primary keys are not the best solution, but what other possibilities are there? Time based doesn't seem right because of collisions which could happen. A GUID comes to mind, is that an option? It looks like generating a GUID in javascript is not that easy. I can do something with natural keys or composite keys. As I'm thinking about it, that looks like the best solution. Can I expect any problems with that?

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