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  • how can I save/keep-in-sync an in-memory graph of objects with the database?

    - by Greg
    Question - What is a good best practice approach for how can I save/keep-in-sync an jn-memory graph of objects with the database? Background: That is say I have the classes Node and Relationship, and the application is building up a graph of related objects using these classes. There might be 1000 nodes with various relationships between them. The application needs to query the structure hence an in-memory approach is good for performance no doubt (e.g. traverse the graph from Node X to find the root parents) The graph does need to be persisted however into a database with tables NODES and RELATIONSHIPS. Therefore what is a good best practice approach for how can I save/keep-in-sync an jn-memory graph of objects with the database? Ideal requirements would include: build up changes in-memory and then 'save' afterwards (mandatory) when saving, apply updates to database in correct order to avoid hitting any database constraints (mandatory) keep persistence mechanism separate from model, for ease in changing persistence layer if needed, e.g. don't just wrap an ADO.net DataRow in the Node and Relationship classes (desirable) mechanism for doing optimistic locking (desirable) Or is the overhead of all this for a smallish application just not worth it and I should just hit the database each time for everything? (assuming the response times were acceptable) [would still like to avoid if not too much extra overhead to remain somewhat scalable re performance]

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  • Windows cmd encoding change causes Python crash.

    - by Alex
    First I chage Windows CMD encoding to utf-8 and run Python interpreter: chcp 65001 python Then I try to print a unicode sting inside it and when i do this Python crashes in a peculiar way (I just get a cmd prompt in the same window). >>> import sys >>> print u'ëèæîð'.encode(sys.stdin.encoding) Any ideas why it happens and how to make it work? UPD: sys.stdin.encoding returns 'cp65001' UPD2: It just came to me that the issue might be connected with the fact that utf-8 uses multi-byte character set (kcwu made a good point on that). I tried running the whole example with 'windows-1250' and got 'ëeaî?'. Windows-1250 uses single-character set so it worked for those characters it understands. However I still have no idea how to make 'utf-8' work here. UPD3: Oh, I found out it is a known Python bug. I guess what happens is that Python copies the cmd encoding as 'cp65001 to sys.stdin.encoding and tries to apply it to all the input. Since it fails to understand 'cp65001' it crushes on any input that contains non-ascii characters.

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  • SQLce DAL Linq to Sql or EntityFramework

    - by bretddog
    Hi, I'm learning databases, using SqlCe, and need business object to database mapping. Currently I try to decide if to use Linq to Sql, or EntityFramework. (I understand a bit L2S, but haven't familiarized with EF yet) The program will only be debeloped and used by myself, so I have good control of the priorities: I don't need to consider potential change of database type or data storage type, as I'm quite certain SQLce will stay sufficient. I DO expect continued development and changes to the data scheme while the program is in active use; change business object properties (Hence database columns), and possibly overall table scheme. So old data must be transported to new scheme. I also want to keep a decent degree of layer separation DAL/BLL, although this may not be necessary, it is good for me to learn these principles. My question is: With these priorities, would I have any benefit by choosing either Linq2Sql vs. EntityFramwork? (and please explain why) Btw, the project involves very simple table scheme with only 4-5 tables and very simple relations. Thanks!

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  • Content Management Systems for Adaptive Content [closed]

    - by andrewap
    Content management systems (CMS) allow us to easily maintain blogs, news sites, general websites, and so on. Many of them are designed to manage pages of content, and provide tools to organize and customize how that content is displayed on the web. However, as explained by Mark Boulton in his Adaptive Content Management article, and by Karen McGrane in her talk on Adapting Ourselves to Adaptive Content, we are increasingly delivering content not just to the web, but also to other platforms and channels. We need tools to manage pieces of content with meaningful metadata attached. Create once, publish everywhere. The main idea is to store content cleanly, without intertwining it with presentation markup specific to the web. Because pieces of content is compartmentalized semantically, it can easily adapt to fit in different platforms and channels. Hence, it's called adaptive content. Let's look at a quick example to compare: Say I manage news articles and events. To create a news article, I would tell the CMS the type of content I'm creating, and be asked to fill in a form with individual fields tailored to news articles (e.g. headline, subtitle, full text, short snippet, and images). — i.e. pieces of content With a traditional web publishing tool, I would probably have had to create a new page under News, and then type in and format the news article in a blank WYSIWYG text editor. — i.e. pages of content As you can see, the first design allows me to individually specify content in its smallest semantic unit. When I want to display or consume it, the system can easily provide the pieces I need. So here's my question: Is there a CMS that is designed specifically with adaptive content in mind, and that is decoupled with the presentation layer? Note: This is not a discussion about the best CMS, or which CMS I should use. I am asking whether a very specific type of tool — CMS designed for adaptive content — exists for developers to use.

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  • What is the best prctice for using security in JAX-WS

    - by kislo_metal
    Here is scenario : I have some web services (JAX-WS) that need to be secured. Currently for authentication needs I providing addition SecurityWService that give authorized user some userid & sessionid that is need to be described in request to other services. It would be more better to use some java security. We have many of them but could not defined what is better to use. Q1 : It is understand that I should use SSL in transport layer, but what should I use for user authorization. Is there is better way to establishing session, validating user etc. ? Here is some key description : Most web services clents is php based. I am using jax-ws implementation as a Stateless session EJB. Deploying to glassfish v3. Q2: what is the best framework / technology for user authorization / authentication in case of using JSF 2.0 and ejb3.1 technologies ( Realms? WSIT? )? Thank You!

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  • How to model parent to child pair in MySQL (SQL)

    - by mikeschuld
    I have a data model that includes element types Stage, Actor, and Form. Logically, Stages can be assigned pairs of ( Form <--- Actor ) which can be duplicated many times (i.e. same person and same form added to the same stage at a later date/time). Right now I am modeling this with these tables: Stage Form Actor Form_Actor _______________ |Id | |FormId | --> Id in Form |ActorId | --> Id in Actor Stage_FormActor __________________ |Id | |StageId | --> Id in Stage |FormActorId | --> Id in Form_Actor I am using CodeSmith to generate the data layer for this setup and none of the templates really know how to handle this type of relationship correctly when generating classes. Ideally, the ORM would have Stage.FormActors where FormActor would be the pair Form, Actor. Is this the correct way to model these relationships. I have tried using all three Ids in one table as well Stage_Form_Actor ______________ |Id | |StageId | --> Id in Stage |FormId | --> Id in Form |ActorId | --> Id in Actor This doesn't really get generated very well either. Ideas?

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  • ASP MVC - Routing Required?

    - by evo_9
    I've been reading up on MVC2 which came in VS2010 and it sounds pretty interesting. I'm actually in the middle of a large multi-tenant application project, and have just started coding the UI. I'm considering changing to MVC as I'm not that far along at this point. I have some questions about the Routing capabilities, namely are they required to use MVC or can I more or less ignore Routing? Or do I have to setup a default routing record that will make things work like standard ASPX (as far as routing alone is concerned)? The reason why I don't want to use Routing is because I've already defined a custom URL 'rewrite' mechanism of my own (which fires on session_start). In addition, I'm using jquery and opens-standards for the entire UI, and MVC's aspx overhead-free approach seems like a better fit based on how I've already started to build the application (I am not using viewstate at all, for example). I guess my big concern is whether the routing can be ignored, of if I will have to re-implement my custom URL rewriting to work with MVC, and if that's the case, how would I do that? As a new Routing routine, or stick with the session_start (if that's even possible?). Lastly, I don't want to use anything even remotely 'intelligent/readable' for the url - for a site like StackOverflow, the readability of the URL is a positive, but the opposite is true if it's not a public website like this one. In fact, it would seem to me that the more friendly MVC routing URL (which indirectly show method names) could pose a security risk on a private, non-public website app like I'm developing. For all these reasons I would love to use the lightweight aspects of MVC but skip the Routing entirely - is this possible?

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  • Using SQL dB column as a lock for concurrent operations in Entity Framework

    - by Sid
    We have a long running user operation that is handled by a pool of worker processes. Data input and output is from Azure SQL. The master Azure SQL table structure columns are approximated to [UserId, col1, col2, ... , col N, beingProcessed, lastTimeProcessed ] beingProcessed is boolean and lastTimeProcessed is DateTime. The logic in every worker role is: public void WorkerRoleMain() { while(true) { try { dbContext db = new dbContext(); // Read foreach (UserProfile user in db.UserProfile .Where(u => DateTime.UtcNow.Subtract(u.lastTimeProcessed) > TimeSpan.FromHours(24) & u.beingProcessed == false)) { user.beingProcessed = true; // Modify db.SaveChanges(); // Write // Do some long drawn processing here ... ... ... user.lastTimeProcessed = DateTime.UtcNow; user.beingProcessed = false; db.SaveChanges(); } } catch(Exception ex) { LogException(ex); Sleep(TimeSpan.FromMinutes(5)); } } // while () } With multiple workers processing as above (each with their own Entity Framework layer), in essence beingProcessed is being used a lock for MutEx purposes Question: How can I deal with concurrency issues on the beingProcessed "lock" itself based on the above load? I think read-modify-write operation on the beingProcessed needs to be atomic but I'm open to other strategies. Open to other code refinements too.

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  • Python C API from C++ app - know when to lock

    - by Alex
    Hi Everyone, I am trying to write a C++ class that calls Python methods of a class that does some I/O operations (file, stdout) at once. The problem I have ran into is that my class is called from different threads: sometimes main thread, sometimes different others. Obviously I tried to apply the approach for Python calls in multi-threaded native applications. Basically everything starts from PyEval_AcquireLock and PyEval_ReleaseLock or just global locks. According to the documentation here when a thread is already locked a deadlock ensues. When my class is called from the main thread or other one that blocks Python execution I have a deadlock. Python Cfunc1() - C++ func that creates threads internally which lead to calls in "my class", It stuck on PyEval_AcquireLock, obviously the Python is already locked, i.e. waiting for C++ Cfunc1 call to complete... It completes fine if I omit those locks. Also it completes fine when Python interpreter is ready for the next user command, i.e. when thread is calling funcs in the background - not inside of a native call I am looking for a workaround. I need to distinguish whether or not the global lock is allowed, i.e. Python is not locked and ready to receive the next command... I tried PyGIL_Ensure, unfortunately I see hang. Any known API or solution for this ? (Python 2.4)

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  • asp.net 4.0 webforms - how to keep ContentPlaceHolder1_ out of client id's in a simple way?

    - by James Manning
    I'm attempting to introduce master pages to an existing webforms site that's avoided using them because of client id mangling in the past (and me not wanting to deal with the mangling and doing <% foo.ClientID % everywhere :) GOAL: use 'static' id values (whatever is in the server control's id attribute) except for data-bound / repeating controls which would break for those cases and therefore need suffixes or whatever to differentiate (basically, Predictable) Now that the site migrated to ASP.NET 4.0, I first attempted to use ClientIDMode of Static (in the web.config) but that broke too many places doing repeating controls (checkboxes inside gridviews, for instance) since they all resulted with the same id. So, I then tried Predictable (again, just in the web.config) so that the repeating controls wouldn't have conflicting id's, and it works well except that the master page content placeholder (which is indeed a naming container) is still reflecting in the resulting client id's (for instance, ContentPlaceHolder1_someCheckbox). Certainly I could leave the web.config setting as static and then go through all the databound/repeating controls switch them to Predictable, but I'm hoping there's some easier/simpler way to get that effect without having to scatter ClientIDMode attributes in those N number of places (or extend all those databound controls with my own usercontrol that just sets clientidmode, or whatever). I even thought of leaving web.config set to static and doing a master or basepage handler (preinit? not sure if that would work or not) that would go walk Controls with OfType<INamingContainer() (might be a better choice on the type, but that seems like a good starting choice looking at repeater and gridview) and then set those to Predictable so I'd get static for all my 'normal' things outside of repeating controls but not have to deal with static inside things like gridview/repeater/etc. I don't see any way to mark the content placeholder such that it 'opts out' of being included in child id's - setting the ID of the placeholder to empty/blank doesn't work as it's a required attribute :) At that point I figured there was a better/simpler way that I was missing and decided to ask on SO :) Edit: I thought about changing all my 'fetch by id' jquery calls from $('#foo') to fetch_by_id('foo') and then having that function return the 'right one' by checking $('#foo').length and then $('#ContentPlaceHolder1_foo').length (and maybe other patterns) or even just have it return $('#foo, #ContentPlaceHolder1_foo') (again, potentially other patterns) but changing all the places I fetch elements by id seemed pretty ugly too, and I'd like to avoid that abstraction layer if possible to do so easily :)

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  • Loading enumerations from database

    - by Mosh
    Hello, I have a problem with mapping .NET enumerations to database tables. Imagine I have a table called Statuses with the following values: StatusID | Name 1 Draft 2 Ready ... ... In the application layer, I can either use a Repository to get all Statuses as an IList object. However, the problem with this approach is that I cannot reference a certain status in my business logic. For example, how can I implement something like this? if (myObject.Status is Ready) do this else if (myObject.Status is Draft) do that... Since the statuses are loaded dynamically, I cannot tell for sure what particular Status object in the List represents the Draft or Ready status. Alternatively, I could just use an enumeration like public enum Statuses { Draft, Ready }; Then I could easily use an enumeration in my business logic. if (myObject.Status == Statuses.Draft) // do something... However, the problem with this approach is that every time the user wants to modify the list of Statuses (adding a new status, or renaming an existing status) the application has to be re-compiled. We cannot load the statuses dynamically from the database. Has anyone else come across a similar situation? Any solutions/patterns? Cheers, Mosh

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  • python can't start a new thread

    - by Giorgos Komnino
    I am building a multi threading application. I have setup a threadPool. [ A Queue of size N and N Workers that get data from the queue] When all tasks are done I use tasks.join() where tasks is the queue . The application seems to run smoothly until suddently at some point (after 20 minutes in example) it terminates with the error thread.error: can't start new thread Any ideas? Edit: The threads are daemon Threads and the code is like: while True: t0 = time.time() keyword_statuses = DBSession.query(KeywordStatus).filter(KeywordStatus.status==0).options(joinedload(KeywordStatus.keyword)).with_lockmode("update").limit(100) if keyword_statuses.count() == 0: DBSession.commit() break for kw_status in keyword_statuses: kw_status.status = 1 DBSession.commit() t0 = time.time() w = SWorker(threads_no=32, network_server='http://192.168.1.242:8180/', keywords=keyword_statuses, cities=cities, saver=MySqlRawSave(DBSession), loglevel='debug') w.work() print 'finished' When the daemon threads are killed? When the application finishes or when the work() finishes? Look at the thread pool and the worker (it's from a recipe ) from Queue import Queue from threading import Thread, Event, current_thread import time event = Event() class Worker(Thread): """Thread executing tasks from a given tasks queue""" def __init__(self, tasks): Thread.__init__(self) self.tasks = tasks self.daemon = True self.start() def run(self): '''Start processing tasks from the queue''' while True: event.wait() #time.sleep(0.1) try: func, args, callback = self.tasks.get() except Exception, e: print str(e) return else: if callback is None: func(args) else: callback(func(args)) self.tasks.task_done() class ThreadPool: """Pool of threads consuming tasks from a queue""" def __init__(self, num_threads): self.tasks = Queue(num_threads) for _ in range(num_threads): Worker(self.tasks) def add_task(self, func, args=None, callback=None): ''''Add a task to the queue''' self.tasks.put((func, args, callback)) def wait_completion(self): '''Wait for completion of all the tasks in the queue''' self.tasks.join() def broadcast_block_event(self): '''blocks running threads''' event.clear() def broadcast_unblock_event(self): '''unblocks running threads''' event.set() def get_event(self): '''returns the event object''' return event

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  • Wildcards in T-SQL LIKE vs. ASP.net parameters

    - by Vinzcent
    In my SQL statement I use wildcards. But when I try to select something, it never select something. While when I execute the query in Microsoft SQL Server Management Studio, it works fine. What am I doing wrong? Click handler protected void btnTitelAuteur_Click(object sender, EventArgs e) { cvalTitelAuteur.Enabled = true; cvalTitelAuteur.Validate(); if (Page.IsValid) { objdsSelectedBooks.SelectMethod = "getBooksByTitleAuthor"; objdsSelectedBooks.SelectParameters.Clear(); objdsSelectedBooks.SelectParameters.Add(new Parameter("title", DbType.String)); objdsSelectedBooks.SelectParameters.Add(new Parameter("author", DbType.String)); objdsSelectedBooks.Select(); gvSelectedBooks.DataBind(); pnlZoeken.Visible = false; pnlKiezen.Visible = true; } } In my Data Access Layer public static DataTable getBooksByTitleAuthor(string title, string author) { string sql = "SELECT 'AUTHOR' = tblAuthors.FIRSTNAME + ' ' + tblAuthors.LASTNAME, tblBooks.*, tblGenres.GENRE " + "FROM tblAuthors INNER JOIN tblBooks ON tblAuthors.AUTHOR_ID = tblBooks.AUTHOR_ID INNER JOIN tblGenres ON tblBooks.GENRE_ID = tblGenres.GENRE_ID " +"WHERE (tblBooks.TITLE LIKE '%@title%');"; SqlDataAdapter da = new SqlDataAdapter(sql, GetConnectionString()); da.SelectCommand.Parameters.Add("@title", SqlDbType.Text); da.SelectCommand.Parameters["@title"].Value = title; DataSet ds = new DataSet(); da.Fill(ds, "Books"); return ds.Tables["Books"]; }

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  • wrapping aspx user controls commands in a transaction

    - by Hans Gruber
    I'm working on heavily dynamic and configurable CMS system. Therefore, many pages are composed of a dynamically loaded set of user controls. To enable loose coupling between containers (pages) and children (user controls), all user controls are responsible for their own persistence. Each User Control is wired up to its data/service layer dependencies via IoC. They also implement an IPersistable interface, which allows the container .aspx page to issue a Save command to its children without knowledge of the number or exact nature of these user controls. Note: what follows is only pseudo-code: public class MyUserControl : IPersistable, IValidatable { public void Save() { throw new NotImplementedException(); } public bool IsValid() { throw new NotImplementedException(); } } public partial class MyPage { public void btnSave_Click(object sender, EventArgs e) { foreach (IValidatable control in Controls) { if (!control.IsValid) { throw new Exception("error"); } } foreach (IPersistable control in Controls) { if (!control.Save) { throw new Exception("error"); } } } } I'm thinking of using declarative transactions from the System.EnterpriseService namespace to wrap the btnSave_Click in a transaction in case of an exception, but I'm not sure how this might be achieved or any pitfalls to such an approach.

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  • swfupload session problem destroy session

    - by saquib
    Hello Friends, I have a problem with swfupload. I am passing session_id() like this /upload-file.php?s=189477fcfa1ec7f630e70a09e1e84cae but its not maintaining session and destroying my current session (logging me out) here is code in file upload. <?php if(isset($_GET['s'])) { session_id($_GET['s']); session_start(); require_once 'admin/class/user.php'; $u = new User(); //Check for user logged in if($u->islogged() == FALSE) { header("location: index.php"); exit(); code continue ..... } because am not logged in server redirect me to the index.php this is swfupload debugger window output SWF DEBUG: ----- END SWF DEBUG OUTPUT ---- SWF DEBUG: SWF DEBUG: Event: fileDialogStart : Browsing files. Multi Select. Allowed file types: *.jpg SWF DEBUG: Select Handler: Received the files selected from the dialog. Processing the file list... SWF DEBUG: Event: fileQueued : File ID: SWFUpload_0_0 SWF DEBUG: Event: fileDialogComplete : Finished processing selected files. Files selected: 1. Files Queued: 1 SWF DEBUG: StartUpload: First file in queue SWF DEBUG: Event: uploadStart : File ID: SWFUpload_0_0 SWF DEBUG: ReturnUploadStart(): File accepted by startUpload event and readied for upload. Starting upload to /upload-file.php?s='189477fcfa1ec7f630e70a09e1e84cae' for File ID: SWFUpload_0_0 SWF DEBUG: Event: uploadProgress (OPEN): File ID: SWFUpload_0_0 SWF DEBUG: Event: uploadProgress: File ID: SWFUpload_0_0. Bytes: 317793. Total: 317793 SWF DEBUG: Event: uploadError: HTTP ERROR : File ID: SWFUpload_0_0. HTTP Status: 302. SWF DEBUG: Event: uploadComplete : Upload cycle complete. SWF DEBUG: StartUpload: First file in queue SWF DEBUG: StartUpload(): No files found in the queue.

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  • Access report not showing data

    - by Brian Smith
    I have two queries that I am using to generate a report from, the problem is when I run the report, three fields do not show any data at all for some reason. Query 1: SELECT ClientSummary.Field3 AS PM, ClientSummary.[Client Nickname 2] AS [Project #], ClientSummary.[Client Nickname 1] AS Customer, ClientSummary.[In Reference To] AS [Job Name], ClientSummary.Field10 AS Contract, (select sum([Billable Slip Value]) from Util_bydate as U1 where U1.[Client Nickname 2] = ClientSummary.[Client Nickname 2]) AS [This Week], (select sum([Billable Slip Value]) from Util as U2 where U2.[Client Nickname 2] = ClientSummary.[Client Nickname 2] ) AS [To Date], [To Date]/[Contract] AS [% Spent], 0 AS Backlog, ClientSummary.[Total Slip Fees & Costs] AS Billed, ClientSummary.Payments AS Paid, ClientSummary.[Total A/R] AS Receivable, [Forms]![ReportMenu]![StartDate] AS [Start Date], [Forms]![ReportMenu]![EndDate] AS [End Date] FROM ClientSummary; Query 2: SELECT JobManagement_Summary.pm, JobManagement_Summary.[project #], JobManagement_Summary.Customer, JobManagement_Summary.[Job Name], JobManagement_Summary.Contract, IIf(IsNull([This Week]),0,[This Week]) AS [N_This Week], IIf(IsNull([To Date]),0,[To Date]) AS [N_To Date], [% Spent], JobManagement_Summary.Backlog, JobManagement_Summary.Billed, JobManagement_Summary.Paid, JobManagement_Summary.Receivable, JobManagement_Summary.[Start Date], JobManagement_Summary.[End Date] FROM JobManagement_Summary; When I run the report from query 2 these 3 fields don't appear. N_This Week, N_To Date and % Spent. All have no data. It isn't the IIF functions, as it doesn't matter if I have those in there or remove them. Any thoughts? If I connect directly to the first recordset it works fine, but then SQL throws the error message: Multi-level GROUP BY cause not allowed in subquery. Is there any way to get around that message to link to it directly or does anyone have ANY clue why these fields are coming back blank? I am at wits end here!

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  • Favourite Features of VS 2010

    - by Noldorin
    With the general public release of Visual Studio 2010 Beta 2 today, this latest version has created a lot of hype and interest. Indeed, the opinion I've gauged is that VS 2010 has resolved a great deal of the minor flaws left over from previous versions, as well as added some particularly useful new code editor and project development tools (in particular the Premium/Ultimate versions). My question here is: what are you favourite new features in VS 2010 that have really got you excited? Or similarly, what are the flaws of VS 2008 that you are most glad to have resolved? There is a wealth of changes in VS 2010, of course, but these are some of the ones that have interested me most (about which I know!). Integrated support for F# (with multi-targeting for .NET 2.0 - 4.0)/ Much improved WPF designer. The VS 2008 was more than a bit buggy at times. Great improvements to the code editor, such as call hierarchy viewing. A decent add-in framework. A greatly expanded testing framework (now capable of database testing, for example) in Premium/Ultimate. Project planning and modelling features in Premium/Ultimate. If I could request one point/feature per post, I think that would be best, so we could vote them individually.

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  • Building asynchronous cache pattern with JSP

    - by merweirdo
    I have a JSP that will take some 8 minutes to render. The code logic itself can not be made more efficient (it will update often and be updated by basically a pointy haired boss). I tried wrapping it with a caching layer like <%@ taglib uri="/WEB-INF/classes/oscache.tld" prefix="oscache" %> <oscache:cache time="60"> <div class="pagecontent"> ..... my logic </div> </oscache:cache> This is nice until the 60 seconds is over. The next query after that blocks until the 8 minutes of rendering is done with again. I would need a way to build a pattern something like: If there is no version of the dynamic content in the cache run the actual logic (and populate the cache for subsequent requests) If there is a non-expired version of the dynamic content in the cache serve the output of the JSP logic from the cache If there is an expired version of the dynamic content in the cache serve the output of the JSP logic still from the cache AND run the JSP logic in the background so that the cache gets updated transparently to the user - avoiding the user have to wait for 8 minutes I found out that at least EHCache might be able to do some asynchronous cache updating but it did not sadly seem to apply to the JSP tags... Also I have to take in 10-20 parameters for the actual logic of the JSP and some of them should be used as a key for caching. Code example and/or pointers would be greatly appreciated. I do not frankly care if the solution provided is extremely ugly. I just want a simple 5 minute caching with asynchronous cache update taking into account some parameters as a key.

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  • Are there more secure alternatives to the .Net SQLConnection class?

    - by KeyboardMonkey
    Hi SO people, I'm very surprised this issue hasn't been discussed in-depth: This article tells us how to use windbg to dump a running .Net process strings in memory. I spent much time researching the SecureString class, which uses unmanaged pinned memory blocks, and keeps the data encrypted too. Great stuff. The problem comes in when you use it's value, and assign it to the SQLConnection.ConnectionString property, which is of the System.String type. What does this mean? Well... It's stored in plain text Garbage Collection moves it around, leaving copies in memory It can be read with windbg memory dumps That totally negates the SecureString functionality! On top of that, the SQLConnection class is non-inheritable, I can't even roll my own with a SecureString property instead; Yay for closed-source. Yay. A new DAL layer is in progress, but for a new major version and for so many users it will be at least 2 years before every user is upgraded, others might stay on the old version indefinitely, for whatever reason. Because of the frequency the connection is used, marshalling from a SecureString won't help, since the immutable old copies stick in memory until GC comes around. Integrated Windows security isn't an option, since some clients don't work on domains, and other roam and connect over the net. How can I secure the connection string, in memory, so it can't be viewed with windbg?

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  • Java try finally variations

    - by Petr Gladkikh
    This question nags me for a while but I did not found complete answer to it yet (e.g. this one is for C# http://stackoverflow.com/questions/463029/initializing-disposable-resources-outside-or-inside-try-finally). Consider two following Java code fragments: Closeable in = new FileInputStream("data.txt"); try { doSomething(in); } finally { in.close(); } and second variation Closeable in = null; try { in = new FileInputStream("data.txt"); doSomething(in); } finally { if (null != in) in.close(); } The part that worries me is that the thread might be somewhat interrupted between the moment resource is acquired (e.g. file is opened) but resulting value is not assigned to respective local variable. Is there any other scenarios the thread might be interrupted in the point above other than: InterruptedException (e.g. via Thread#interrupt()) or OutOfMemoryError exception is thrown JVM exits (e.g. via kill, System.exit()) Hardware fail (or bug in JVM for complete list :) I have read that second approach is somewhat more "idiomatic" but IMO in the scenario above there's no difference and in all other scenarios they are equal. So the question: What are the differences between the two? Which should I prefer if I do concerned about freeing resources (especially in heavily multi-threading applications)? Why? I would appreciate if anyone points me to parts of Java/JVM specs that support the answers.

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  • How can I make this SQL query more efficient? PHP.

    - by Alan Grant
    Hi all, I have a system whereby a user can view categories that they've subscribed to individually, and also those that are available in the region they belong in by default. So, the tables are as follows: Categories UsersCategories RegionsCategories I'm querying the db for all the categories within their region, and also all the individual categories that they've subscribed to. My query is as follows: Select * FROM (categories c) LEFT JOIN users_categories uc on uc.category_id = c.id LEFT JOIN regions_categories rc on rc.category_id = c.id WHERE (rc.region_id = ? OR uc.user_id = ?) At least I believe that's the query, I'm creating it using Cake's ORM layer, so the exact one is: $conditions = array( array( "OR" => array ( 'RegionsCategories.region_id' => $region_id, 'UsersCategories.user_id' => $user_id ) )); $this->find('all', $conditions); This turns out to be incredibly slow (sometimes around 20 seconds or so. Each table has around 5,000 rows). Is my design at fault here? How can I retrieve both the users' individual categories and those within their region all in one query without it taking ages? Thanks!

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  • Reading same file from multiple threads in C#

    - by Gustavo Rubio
    Hi. I was googling for some advise about this and I found some links. The most obvious was this one but in the end what im wondering is how well my code is implemented. I have basically two classes. One is the Converter and the other is ConverterThread I create an instance of this Converter class that has a property ThreadNumber that tells me how many threads should be run at the same time (this is read from user) since this application will be used on multi-cpu systems (physically, like 8 cpu) so it is suppossed that this will speed up the import The Converter instance reads a file that can range from 100mb to 800mb and each line of this file is a tab-delimitted value record that is imported to another destination like a database. The ConverterThread class simply runs inside the thread (new Thread(ConverterThread.StartThread)) and has event notification so when its work is done it can notify the Converter class and then I can sum up the progress for all these threads and notify the user (in the GUI for example) about how many of these records have been imported and how many bytes have been read. It seems, however that I'm having some trouble because I get random errors about the file not being able to be read or that the sum of the progress (percentage) went above 100% which is not possible and I think that happens because threads are not being well managed and probably the information returned by the event is malformed (since it "travels" from one thread to another) Do you have any advise on better practices of implementation of threads so I can accomplish this? Thanks in advance.

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  • Loading an XML configuration file BEFORE the flex application loads

    - by Shahar
    Hi, We are using an XML file as an external configuration file for several parameters in our application (including default values for UI components and properties values of some service layer objects). The idea is to be able to load the XML configuration file before the flex application initializes any of its components. This is crucial because XML loading is processed a-synchronously in flex, which can potentially cause race-conditions in the application. For example: the configuration file holds the endpoint URL of a web service used to obtain data from the server. The URL resides in the XML because we want to allow our users to alter the endpoint URL according to their environment. Now because the endpoint URL is retrieved only after the XML has been completely loaded, some of the application's components might be invoking operations on this web service before it is initialized with the correct endpoint. The trivial solution would have been to suspend the initialization of the application until the complete event is dispatched by the loader. But it appears that this solution is far from being trivial. I haven't found a single solution that allows me to load the XML before any other object in the application. Can anyone advice or comment on this matter? Regards, Shahar

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  • Implementing java FixedTreadPool status listener

    - by InsertNickHere
    Hi there, it's about an application which is supposed to process (VAD, Loudness, Clipping) a lot of soundfiles (e.g. 100k). At this time, I create as many worker threads (callables) as I can put into memory, and then run all with a threadPool.invokeAll(), write results to file system, unload processed files and continue at step 1. Due to the fact it's an app with a GUI, i don't want to user to feel like the app "is not responding" while processing all soundfiles. (which it does at this time cause invokeAll is blocking). Im not sure what is a "good" way to fix this. It shall not be possible for the user to do other things while processing, but I'd like to show a progress bar like "10 of 100000 soundfiles are done". So how do I get there? Do I have to create a "watcher thread", so that every worker hold a callback on it? I'm quite new to multi threading, and don't get the idea of such a mechanisem.. If you need to know: I'm using SWT/JFace. Regards, InsertNickHere

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  • Game architecture: modeling different steps/types of UI

    - by Sander
    I have not done any large game development projects, only messed around with little toy projects. However, I never found an intuitive answer to a specific design question. Namely, how are different types/states of UI modeled in games? E.g. how is a menu represented? How is it different from a "game world" state (let's use an FPS as an example). How is an overlaid menu on top of a "game world" modeled? Let's imagine the main loop of a game. Where do the game states come into play? It it a simple case-by-case approach? if (menu.IsEnabled) menu.Process(elapsedTime); if (world.IsEnabled) world.Process(elapsedTime); if (menu.IsVisible) menu.Draw(); if (world.IsVisible) world.Draw(); Or are menu and world represented somewhere in a different logic layer and not represented at this level? (E.g. a menu is just another high-level entity like e.g. player input or enemy manager, equal to all others) foreach (var entity in game.HighLevelEntities) entity.Process(elapsedTime); foreach (var entity in game.HighLevelEntities) entity.Draw(elapsedTime); Are there well-known design patterns for this? Come to think of it, I don't know any game-specific design patterns - I assume there are others, as well? Please tell me about them.

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