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  • Process xml-like log file queue

    - by Zsolt Botykai
    Hi all, first of all: I'm not a programmer, never was, although had learn a lot during my professional carreer as a support consultant. Now my task is to process - and create some statistics about a constantly written and rapidly growing XML like log file. It's not valid XML, because it does not have a proper <root> element, e.g. the log looks like this: <log itemdate="somedate"> <field id="0" /> ... </log> <log itemdate="somedate+1"> <field id="0" /> ... </log> <log itemdate="somedate+n"> <field id="0" /> ... </log> E.g. I have to count all the items with field id=0. But most of the solutions I had found (e.g. using XPath) reports an error about the garbage after the first closing </log>. Most probably I can use python (2.6, although I can compile 3.x as well), or some really old perl version (5.6.x), and recently compiled xmlstarlet which really looks promising - I was able to create the statistics for a certain period after copying the file, and pre- & appending the opening and closing root element. But this is a huge file and copying takes time as well. Isn't there a better solution? Thanks in advance!

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  • Spawning a thread in python

    - by morpheous
    I have a series of 'tasks' that I would like to run in separate threads. The tasks are to be performed by separate modules. Each containing the business logic for processing their tasks. Given a tuple of tasks, I would like to be able to spawn a new thread for each module as follows. from foobar import alice, bob charles data = getWorkData() # these are enums (which I just found Python doesn't support natively) :( tasks = (alice, bob, charles) for task in tasks # Ok, just found out Python doesn't have a switch - @#$%! # yet another thing I'll need help with then ... switch case alice: #spawn thread here - how ? alice.spawnWorker(data) No prizes for guessing I am still thinking in C++. How can I write this in a Pythonic way using Pythonic 'enums' and 'switch'es, and be able to run a module in a new thread. Obviously, the modules will all have a class that is derived from a ABC (abstract base class) called Plugin. The spawnWorker() method will be declared on the Plugin interface and defined in the classes implemented in the various modules. Maybe, there is a better (i.e. Pythonic) way of doing all this?. I'd be interested in knowing

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  • What is your personal approach/take on commenting?

    - by Trae
    Duplicate What are your hard rules about commenting? A Developer I work with had some things to say about commenting that were interesting to me (see below). What is your personal approach/take on commenting? "I don't add comments to code unless its a simple heading or there's a platform-bug or a necessary work-around that isn't obvious. Code can change and comments may become misleading. Code should be self-documenting in its use of descriptive names and its logical organization - and its solutions should be the cleanest/simplest way to perform a given task. If a programmer can't tell what a program does by only reading the code, then he's not ready to alter it. Commenting tends to be a crutch for writing something complex or non-obvious - my goal is to always write clean and simple code." "I think there a few camps when it comes to commenting, the enterprisey-type who think they're writing an API and some grand code-library that will be used for generations to come, the craftsman-like programmer that thinks code says what it does clearer than a comment could, and novices that write verbose/unclear code so as to need to leave notes to themselves as to why they did something."

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  • How to maintain a persistant network-connection between two applications over a network?

    - by John
    I was recently approached by my management with an interesting problem - where I am pretty sure I am telling my bosses the correct information but I really want to make sure I am telling them the correct stuff. I am being asked to develop some software that has this function: An application at one location is constantly processing real-time data every second and only generates data if the underlying data has changed in any way. On the event that the data has changed send the results to another box over a network Maintains a persistent connection between the both machines, altering the remote box if for some reason the network connection went down From what I understand, I imagine that I need to do some reading on doing some sort of TCP/IP socket-level stuff. That way if the connection is dropped the remote location will be aware that the data it has received may be stale. However management seems to be very convinced that this can be accomplished using SOAP. I was under the impression that SOAP is more or less a way for a client to initiate a procedure from a server and get some results via the HTTP protocol. Am I wrong in assuming this? I haven't been able to find much information on how SOAP might be able to solve a problem like this. I feel like a lot of people around my office are using SOAP as a buzzword and that has generated a bit of confusion over what SOAP actually is - and is capable of. Any thoughts on how to accomplish this task would be appreciated!

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  • What is the best free cross-platform OpenGL GUI library for a video game?

    - by Jim Buck
    It must come with source. I've looked at these which look semi-promising: glgooey, guichan, and cegui. I've come across others that look more Windows-y than game-y, but that's not the direction I am looking to go in. I would like some simple functionality of typical controls (lists, dropdown box, etc.) but with support for graphical widgets that you would normally find in game frontends. Mouse clicking, dragging, dropping, etc. and sound effect hooks would be nice. (These libs often leave hooks for the external system to tell it when/where mouse events are occurring.) It would get rendered on top of what my own 3D engine is rendering for the game, so it must be able to play nicely with rendering code outside of the lib. The best criteria is whether or not a reasonable 2D game could be implemented just with the GUI library and minimal glue code. (By glue code, I mean init code, hooking up the mouse, and game logic.) I am creating a 3D game, but this criteria gives a pretty solid idea of what level of interactivity I would like in the GUI.

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  • Two pass JSP page rendering

    - by dotsid
    Suppose an example. I have following interface: public interface DataSource<T> { Future<T> fetch(); } This datasource can do asynchronous data fetching. And we have following tag for using datasource in JSP: <html> <d:fetch from="${orderDS}" var="orders"> <c:foreach in="${orders}" var="order"> <div class="order"> <c:out value="${order.title}" /> </div> </c:foreach> </d:fetch> </html> So, what I want? I want JSP rendering engine to call my custom tag (FetchTag in this example) twice. On first call FetchTag will do DataSource.fetch() call and save Future locally as a object field. On second call FetchTag do Future.get() call and will be blocked until data becomes available. Is there any way to do such a thing?

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  • ASP.Net MVC - how can I easily serialize query results to a database?

    - by Mortanis
    I've been working on a little property search engine while I learn ASP.Net MVC. I've gotten the results from various property database tables and sorted them into a master generic property response. The search form is passed via Model Binding and works great. Now, I'd like to add pagination. I'm returning the chunk of properties for the current page with .Skip() and .Take(), and that's working great. I have a SearchResults model that has the paged result set and various other data like nextPage and prevPage. Except, I no longer have the original form of course to pass to /Results/2. Previously I'd have just hidden a copy of the form and done a POST each time, but it seems inelegant. I'd like to serialize the results to my MS SQL database and return a unique key for that results set - this also helps with a "Send this query to a friend!" link. Killing two birds with one stone. Is there an easy way to take an IQueryable result set that I have, serialize it, stick it into the DB, return a unique key and then reverse the process with said key? I'm using Linq to SQL currently on a MS SQL Express install, though in production it'll be on MS SQL 2008.

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  • python os.mkfifo() for Windows

    - by user302099
    Hello. Short version (if you can answer the short version it does the job for me, the rest is mainly for the benefit of other people with a similar task): In python in Windows, I want to create 2 file objects, attached to the same file (it doesn't have to be an actual file on the hard-drive), one for reading and one for writing, such that if the reading end tries to read it will never get EOF (it will just block until something is written). I think in linux os.mkfifo() would do the job, but in Windows it doesn't exist. What can be done? (I must use file-objects). Some extra details: I have a python module (not written by me) that plays a certain game through stdin and stdout (using raw_input() and print). I also have a Windows executable playing the same game, through stdin and stdout as well. I want to make them play one against the other, and log all their communication. Here's the code I can write (the get_fifo() function is not implemented, because that's what I don't know to do it Windows): class Pusher(Thread): def __init__(self, source, dest, p1, name): Thread.__init__(self) self.source = source self.dest = dest self.name = name self.p1 = p1 def run(self): while (self.p1.poll()==None) and\ (not self.source.closed) and (not self.source.closed): line = self.source.readline() logging.info('%s: %s' % (self.name, line[:-1])) self.dest.write(line) self.dest.flush() exe_to_pythonmodule_reader, exe_to_pythonmodule_writer =\ get_fifo() pythonmodule_to_exe_reader, pythonmodule_to_exe_writer =\ get_fifo() p1 = subprocess.Popen(exe, shell=False, stdin=subprocess.PIPE, stdout=subprocess.PIPE) old_stdin = sys.stdin old_stdout = sys.stdout sys.stdin = exe_to_pythonmodule_reader sys.stdout = pythonmodule_to_exe_writer push1 = Pusher(p1.stdout, exe_to_pythonmodule_writer, p1, '1') push2 = Pusher(pythonmodule_to_exe_reader, p1.stdin, p1, '2') push1.start() push2.start() ret = pythonmodule.play() sys.stdin = old_stdin sys.stdout = old_stdout

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  • Are game engines developed in the USA?

    - by numerical25
    I just finished talking to a Flashpoint Academy recruiter about their curriculum. I told him that after I graduate, I would like to go more in-depth with learning game engines and how to make games. So I asked him did their school teach anything in regards to learning any graphics API such as DirectX. He asked me to elaborate a little more as if he was not sure what I was talking about. So I asked did their school teach on how to build game engines. He said "no we only teach with the tools at hand, such as XNA, or the Unreal engine". He further said "most jobs that deal with building game engines go overseas and most of creative work is done in the United States." To be honest, I really had no intentions of going to this school. I just wanted to learn more about the school in case I had second thoughts somewhere down the line. To me I thought it was a bunch of BS, but my question is to you guys, "is it" ??

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  • Best way to migrate export/import from SQL Server to oracle

    - by matao
    Hi guys! I'm faced with needing access for reporting to some data that lives in Oracle and other data that lives in a SQL Server 2000 database. For various reasons these live on different sides of a firewall. Now we're looking at doing an export/import from sql server to oracle and I'd like some advice on the best way to go about it... The procedure will need to be fully automated and run nightly, so that excludes using the SQL developer tools. I also can't make a live link between databases from our (oracle) side as the firewall is in the way. The data needs to be transformed in the process from a star schema to a de-normalised table ready for reporting. What I'm thinking about is writing a monster query for SQL Server (which I mostly have already) that will denormalise and read out the data from SQL Server into a flat file using the sql server equivalent of sqlplus as a scheduled task, dump into a Well Known Location, then on the oracle side have a cron job that copies down the file and loads it with sql loader and rebuilds indexes etc. This is all doable, but very manual. Is there one or a combination of FOSS or standard oracle/SQL Server tools that could automate this for me? the Irreducible complexity is the query on one side and building indexes on the other, but I would love to not have to write the CSV dumping detail or the SQL loader script, just say dump this view out to CSV on one side, and on the other truncate and insert into this table from CSV and not worry about mapping column names and all other arcane sqlldr voodoo... best practices? thoughts? comments? edit: I have about 50+ columns all of varying types and lengths in my dataset, which is why I'd prefer to not have to write out how to generate and map each single column...

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  • Inserting default "admin" user into database during Rails App startup

    - by gbc
    I'm building my first real rails application for a little in-house task. Most of the application tasks require authentication/authorization. The first time the app starts up (or starts with a wiped db), I'd like the process to be: User logs into the admin panel using "admin" & "admin" for authentication info. User navigates to admin credentials editing page and changes name and password to something safer so that "admin" & "admin" is no longer a valid login. To achieve this result, I'd like to stuff a default username & password combination into the database on if the application starts up and detects that there are no user credentials in the 'users' table. For example: if User.count == 0 User.create(:name => "admin", :password => "admin") end However, I'm unsure where to place that code. I tried adding an initializer script in the config/initializers, but the error I received appeared to indicate that the model classes weren't yet loaded into the application. So I'm curious to know at what point I can hook into the application startup cycle and insert data into the database through ActiveRecord before requests are dispatched.

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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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  • Is there a more efficient way to do this?

    - by garethdn
    I'm hoping there is a better way to the following. I'm creating a jigsaw-type application and this is the current code i'm using: -(void) touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { UITouch *touch = [touches anyObject]; //location of current touch CGPoint location = [touch locationInView:self.view]; if ([touch view] == img1) { [self animateFirstTouch:img1 withLocation:location]; } else if ([touch view] == img2) { [self animateFirstTouch:img2 withLocation:location]; } else if ([touch view] == img3) { [self animateFirstTouch:img3 withLocation:location]; } else if ([touch view] == img4) { [self animateFirstTouch:img4 withLocation:location]; } else if { ...... ...... } else if ([touch view] == img40) { [self animateFirstTouch:img40 withLocation:location]; return; } } I'm hoping that there is a better, more efficieny way to do this, rather than naming every image. I'm thinking something like, if touch view is equal to a UIImageView, then perform some task. The same for touchesEnded: -(void) touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event { UITouch *touch = [touches anyObject]; //location of current touch CGPoint location = [touch locationInView:self.view]; if ([touch view] == image1) { [self animateReleaseTouch:image1 withLocation:location]; } else if ([touch view] == image2) { [self animateReleaseTouch:image2 withLocation:location]; } else if ([touch view] == image3) { [self animateReleaseTouch:image3 withLocation:location]; } else if ([touch view] == image4) { [self animateReleaseTouch:image4 withLocation:location]; } else if{ ...... ...... } else if ([touch view] == image40) { [self animateReleaseTouch:image40 withLocation:location]; } return; } Any help please?

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  • How to deploy to multiple redundant production servers with "cap deploy"?

    - by Chad Johnson
    Capistrano is working great to deploy to a single server. However, I have multiple production API servers for my web application. When I deploy, my code needs to get deployed to every API server at once. Specifying each server manually is NOT the solution I am looking for (e.g. I don't want to do "cap api1 deploy; cap api2 deploy"). Is there a way, using Capistrano, to deploy to all servers at once, with just a simple "cap deploy"? I'm wondering what changes I would need to make to a typical deploy.rb file, whether I'd need to create a separate file for each server, and whether and how the Capfile would need to be changed. Also, I need to be able to specify a different deploy_to path for each server. And ideally, I wouldn't have to repeat things in different config files for different servers (eg. wouldn't have to specify :repository, :application, etc. multiple times). I have spent hours searching Google on this and looking through tutorials, but I have found nothing helpful. Here is a snippet from my current deploy.rb file: set :application, "testapplication" set :repository, "ssh://domain.com//srv/hg/#{application}" set :scm, :mercurial set :deploy_to, "/srv/www/#{application}" role :web, "domain.com" role :app, "domain.com" role :db, "domain.com", :primary => true, :norelease => true Should I just use the multistage extension and do this? task :deploy_everything do system "cap api1 deploy" system "cap api2 deploy" system "cap api2 deploy" end That could work, but I feel like this isn't what this extension is meant for...

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  • How to copy files without slowing down my app?

    - by Kevin Gebhardt
    I have a bunch of little files in my assets which need to be copied to the SD-card on the first start of my App. The copy code i got from here placed in an IntentService works like a charm. However, when I start to copy many litte files, the whole app gets increddible slow (I'm not really sure why by the way), which is a really bad experience for the user on first start. As I realised other apps running normal in that time, I tried to start a child process for the service, which didn't work, as I can't acess my assets from another process as far as I understood. Has anybody out there an idea how a) to copy the files without blocking my app b) to get through to my assets from a private process (process=":myOtherProcess" in Manifest) or c) solve the problem in a complete different way Edit: To make this clearer: The copying allready takes place in a seperate thread (started automaticaly by IntentService). The problem is not to separate the task of copying but that the copying in a dedicated thread somehow affects the rest of the app (e.g. blocking to many app-specific resources?) but not other apps (so it's not blocking the whole CPU or someting) Edit2: Problem solved, it turns out, there wasn't really a problem. See my answer below.

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  • PHP5 getrusage() returning incorrect information?

    - by Andrew
    I'm trying to determine CPU usage of my PHP scripts. I just found this article which details how to find system and user CPU usage time (Section 4). However, when I tried out the examples, I received completely different results. The first example: sleep(3); $data = getrusage(); echo "User time: ". ($data['ru_utime.tv_sec'] + $data['ru_utime.tv_usec'] / 1000000); echo "System time: ". ($data['ru_stime.tv_sec'] + $data['ru_stime.tv_usec'] / 1000000); Results in: User time: 29.53 System time: 2.71 Example 2: for($i=0;$i<10000000;$i++) { } // Same echo statements Results: User time: 16.69 System time: 2.1 Example 3: $start = microtime(true); while(microtime(true) - $start < 3) { } // Same echo statements Results: User time: 34.94 System time: 3.14 Obviously, none of the information is correct except maybe the system time in the third example. So what am I doing wrong? I'd really like to be able to use this information, but it needs to be reliable. I'm using Ubuntu Server 8.04 LTS (32-bit) and this is the output of php -v: PHP 5.2.4-2ubuntu5.10 with Suhosin-Patch 0.9.6.2 (cli) (built: Jan 6 2010 22:01:14) Copyright (c) 1997-2007 The PHP Group Zend Engine v2.2.0, Copyright (c) 1998-2007 Zend Technologies

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  • Data structure to build and lookup set of integer ranges

    - by actual
    I have a set of uint32 integers, there may be millions of items in the set. 50-70% of them are consecutive, but in input stream they appear in unpredictable order. I need to: Compress this set into ranges to achieve space efficient representation. Already implemented this using trivial algorithm, since ranges computed only once speed is not important here. After this transformation number of resulting ranges is typically within 5 000-10 000, many of them are single-item, of course. Test membership of some integer, information about specific range in the set is not required. This one must be very fast -- O(1). Was thinking about minimal perfect hash functions, but they do not play well with ranges. Bitsets are very space inefficient. Other structures, like binary trees, has complexity of O(log n), worst thing with them that implementation make many conditional jumps and processor can not predict them well giving poor performance. Is there any data structure or algorithm specialized in integer ranges to solve this task?

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  • Crystal Reports.NET problems accessing FieldObject for page count

    - by Stuart A
    Hi, We're using Crystal Reports.NET that was bundled with VS2005. We have a confirmation booking form letter report that we want to batch print. Generally this prints one page per person on letterhead paper, however occasionally if they've booked lots of courses the letter rolls over to two pages. The second page should not be printed to letterhead paper. Basically, because it's a rare occurance I was just going to print the lot and pause if a particular letter went over 1 page. I.e. Load the report, grab the page count, hollah at the user if it's more than one page otherwise carry on regardless. I have dropped a TotalPageCount on the footer of my report (Which I would supress if it worked!) and then try and read it in my application. Once I've loaded the document I am trying to call report.ReportDefinition.ReportObjects("TotalPageCount1") Which is of type CrystalDecisions.CrystalReports.Engine.FieldObject I cannot seem to get the value out of this for love nor money (nor any amount of cursing and swearing!) I can read any items of type TextObject, but if I append the TotalPageCount to a text field, it shows correctly in the report but then returns "Page count: TotalPageCount" rather than "Page count: 1" for example. Soo, short of going out of my mind, does anyone have any suggestions? Either a way to read the value or a way round it. The printer doesn't have multiple trays, though even if we got one, I'm not sure how to convince crystal to print different pages to different trays. Best regards, Stuart P.S. - is it a sign that the "crystal-reports" tag has a count of 666? :O(

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  • Why is my user control not instanciated on a postback?

    - by Antoine
    Hi, I'd like to set the trigger of an UpdatePanel to a user control outside the UpdatePanel on the same page . The user control is added at design time, not at runtime. If I statically declare the trigger, I get an error "A control with ID 'xx' cannot be found for the trigger in UpdatePanel". I tried to add the trigger at runtime in Page_Init or Page_Load, but it fails with the user control being null, although it has ViewState enabled. Has someone an idea on how to solve this? Here is the code of the user control: <%@ Control Language="C#" AutoEventWireup="true" CodeFile="ComponentDropDownControl.ascx.cs" Inherits="ComponentDropDownControl" EnableViewState="true" %> <asp:DropDownList ID="ComponentDropDown" runat="server" DataSourceID="ComponentFile" DataTextField="name" DataValueField="name" OnSelectedIndexChanged="ComponentDropDown_SelectedIndexChanged" AutoPostBack="True" EnableTheming="True"> </asp:DropDownList><asp:XmlDataSource ID="ComponentFile" runat="server" DataFile="~/App_Data/Components.xml" XPath="//component"></asp:XmlDataSource> And here it is in the aspx page: <%@ Page Language="C#" MasterPageFile="~/MasterPage.master" AutoEventWireup="true" CodeFile="create.aspx.cs" Inherits="create" Title="Create task" %> <%@ Register Src="ComponentDropDownControl.ascx" TagName="ComponentDropDownControl" TagPrefix="uc1" %> ... <uc1:ComponentDropDownControl ID="CustomComponentDropDown" runat="server" EnableViewState="true" /> In the Page_Load function of the aspx page, the following lines work at first time, but fail on the first PostBack (line 2, CustomComponentDropDown is null). AsyncPostBackTrigger trigger = new AsyncPostBackTrigger(); trigger.ControlID = CustomComponentDropDown.UniqueID.ToString(); UpdatePanel1.Triggers.Add(trigger);

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  • How can I call `update_attribute` for a list item in rails then actually update the html using jquery?

    - by Patrick Connor
    I want my users to be able to mark one or more items from an index view as "Active" or "Inactive" using a link. The text for the link should be state aware - so it might default to "Mark as Active" if the corresponding attribute was false or null, and "Mark as Inactive" if true. Once the user clicks the link and the attribute is updated in the controller, the link-text should update based on the new state. I am WAY off here, but this is a small sample of the code I have been trying... CONTROLLER ... respond_to :html, :js ... def update @item = Item.find(params[:id]) if @item.update_attributes(params[:item]) #Not sure of how to respond to .js here end end ... update.js.erb #how do I identify which element to update? $('#item[13456]').html("State aware text for link_to") VIEW - for item in @items = item.name = link_to "Mark as Active", item_path(item), :method => :put, :remote => true. :id => "item[#{item.id}]" I am happy to read any APIs, blogs, tutorials, etc. I just can't seem to get my hands/mind around this task. Any help or guidance is greatly appreciated!

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  • For business people to manage, keep binary images in MySQL or just the urls?

    - by Michael Mao
    Hello everyone: I am working on a task to enable image uploading and auto-scaling(from full sized to thumbnail) by jQuery & PHP. I can naturally come up with two approaches : First, store both images as binary objects directly into MySQL; Second, store only urls to the images and keep the images somewhere on server. The images are for everyone to view, so there are no security restrictions, as far as I know. Personally I don't have any preference, however, at the end of the day, it is the business people that are going to manage the images as part of the system(CRUD). So I am wondering which seems to be a bit better for them? Of course I am building a easy-to-use, visualize web interface for the staff to control the process, but I am not sure if that is enough. Lessons told me that if I don't think for the future and seek the most flexible approach, the I will probably screw myself sooner or later. PS. The following link is what I've found so far, which is pretty cool, no flash involved :) Andrew Valum's ajax image upload jQuery plugin

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  • Thread management advice - Is TPL a good idea?

    - by Ian
    I'm hoping to get some advice on the use of thread managment and hopefully the task parallel library, because I'm not sure I've been going down the correct route. Probably best is that I give an outline of what I'm trying to do. Given a Problem I need to generate a Solution using a heuristic based algorithm. I start of by calculating a base solution, this operation I don't think can be parallelised so we don't need to worry about. Once the inital solution has been generated, I want to trigger n threads, which attempt to find a better solution. These threads need to do a couple of things: They need to be initalized with a different 'optimization metric'. In other words they are attempting to optimize different things, with a precedence level set within code. This means they all run slightly different calculation engines. I'm not sure if I can do this with the TPL.. If one of the threads finds a better solution that the currently best known solution (which needs to be shared across all threads) then it needs to update the best solution, and force a number of other threads to restart (again this depends on precedence levels of the optimization metrics). I may also wish to combine certain calculations across threads (e.g. keep a union of probabilities for a certain approach to the problem). This is probably more optional though. The whole system needs to be thread safe obviously and I want it to be running as fast as possible. I tried quite an implementation that involved managing my own threads and shutting them down etc, but it started getting quite complicated, and I'm now wondering if the TPL might be better. I'm wondering if anyone can offer any general guidance? Thanks...

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  • Upcasting without any added data fields.

    - by Benjamin Manns
    In my project I have a generic Packet class. I would like to be able to upcast to other classes (like LoginPacket or MovePacket). The base class contains a command and arguments (greatly simplified): public class Packet { public String Command; public String[] Arguments; } I would like to have be able to convert from Packet to LoginPacket (or any other) based on a check if Packet.Command == "LOGIN". The login packet would not contain any new data members, but only methods for accessing specific arguments. For example: public class LoginPacket : Packet { public String Username { get { return Arguments[0]; } set { Arguments[0] == value; } } public String Password { get { return Arguments[1]; } set { Arguments[1] == value; } } } It would be great if I could run a simple code that would cast from Packet to LoginPacket with something like LoginPacket _Login = (LoginPacket)_Packet;, but that throws a System.InvalidCastException. It seems like this would be an easy task, as no new data is included, but I can't figure out any other way than copying everything from the Packet class to a new LoginPacket class.

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  • Java: design for using many executors services and only few threads

    - by Guillaume
    I need to run in parallel multiple threads to perform some tests. My 'test engine' will have n tests to perform, each one doing k sub-tests. Each test result is stored for a later usage. So I have n*k processes that can be ran concurrently. I'm trying to figure how to use the java concurrent tools efficiently. Right now I have an executor service at test level and n executor service at sub test level. I create my list of Callables for the test level. Each test callable will then create another list of callables for the subtest level. When invoked a test callable will subsequently invoke all subtest callables test 1 subtest a1 subtest ...1 subtest k1 test n subtest a2 subtest ...2 subtest k2 call sequence: test manager create test 1 callable test1 callable create subtest a1 to k1 testn callable create subtest an to kn test manager invoke all test callables test1 callable invoke all subtest a1 to k1 testn callable invoke all subtest an to kn This is working fine, but I have a lot of new treads that are created. I can not share executor service since I need to call 'shutdown' on the executors. My idea to fix this problem is to provide the same fixed size thread pool to each executor service. Do you think it is a good design ? Do I miss something more appropriate/simple for doing this ?

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  • Findbugs and comparing

    - by Rob Goodwin
    I recently started using the findbugs static analysis tool in a java build I was doing. The first report came back with loads of High Priority warnings. Being the obsessive type of person, I was ready to go knock them all out. However, I must be missing something. I get most of the warnings when comparing things. Such as the following code: public void setSpacesPerLevel(int value) { if( value >= 0) { ... produces a high priority warning at the if statement that reads. File: Indenter.java, Line: 60, Type: BIT_AND_ZZ, Priority: High, Category: CORRECTNESS Check to see if ((...) & 0) == 0 in sample.Indenter.setSpacesPerLevel(int) I am comparing an int to an int, seems like a common thing. I get quite a few of that type of error with similar simple comparisons. I have alot of other high priority warnings on what appears to be simple code blocks. Am I missing something here? I realize that static analysis can produce false positives, but the errors I am seeing seem too trivial of a case to be a false positive. This one has me scratching my head as well. for(int spaces = 0;spaces < spacesPerLevel;spaces++){... Which gives the following findbugs warning: File: Indenter.java, Line: 160, Type: IL_INFINITE_LOOP, Priority: High, Category: CORRECTNESS There is an apparent infinite loop in sample.Indenter.indent() This loop doesn't seem to have a way to terminate (other than by perhaps throwing an exception). Any ideas? So basically I have a handful of files and 50-60 high priority warnings similar to the ones above. I am using findbugs 1.3.9 and calling it from the findbugs ant task

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