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• What messaging technologies in windows-ce for guaranteed msg delivery?

  - by Aidanapword

  We are building a windows-ce (6.0R3) based device that requires guaranteed and audit-ready message delivery (including store & forward) up to and down from the cloud. I have been looking for choices beyond: MSMQ a proprietary solution (what our prototype device is using) AMQP (I have not found any RabbitMQ clients for CE, by example) ... are there any others? We will be transporting sensitive data (who isn't?!?!) over a public network, and large scale options are required. Anything running on an embedded device will be performance sensitive too.

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• MySQL locking problem

  - by teehoo

  I have a simple setup of a set of writers and a set of readers working with a MySQL ISAM table. The writers are only inserting rows while the readers are only checking for new rows. OK, so I know that I don't need a lock in this situation, since I'm not modifying existing rows. However my Writers are accessing one more table that does need a lock. I piece of information seems irrelevant except for the following limitation stated in the MySQL documentation: A session that requires locks must acquire all the locks that it needs in a single LOCK TABLES statement. While the locks thus obtained are held, the session can access only the locked tables. For example, in the following sequence of statements, an error occurs for the attempt to access t2 because it was not locked in the LOCK TABLES statement: So to access the table I want to insert rows into, I NEED to lock it, which is causing me performance problems. Any suggestions of how to get around this?

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• Database indexes - what should they be

  - by WebweaverD

  Most of my database tables have a clear unique index through which lookups are done 90% of the time but I am a bit unsure on this one - I have a table which keeps track of user rating totals for items in my database, I now want to add another table, to track individual ratings with an ip address column to make sure no one can rate something twice. Since I can see this becoming a big, high use table it is important to optimize it correctly. (MYSQL table) This table will have the following fields: rating_id(always - unique), item_id (always - not unique), user_id (optional - not unique), ip_address (always - not unique), rating_value(always - not unique), has_review(bool) Now I envisions 90% the queries going something like this: When a user rates something - select where item_id = x and ip_address = y, (if rows = 0) insert rating When in user account pages - select where ip_address = x or username = y Now none of the fields searched on are unique, can I still use them as indexes (for example item _id and ip_address), can I have two indexes and will this still improve performance over a non indexed table?

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• Semantic stuff (RDF, OWL) on mobile phones - is it possible?

  - by Brian Schimmel

  I'm thinking about using semantic (web) technogies like RDF and OWL in an application on mobile devices. Currently I'm targeting android, but I'd also be interested in the possibilities on the iPhone and on J2ME. I would like to use a lib instead of implementing everything from scratch. I know that there are some libraries and frameworks like Jena, Redland, Protégé but they don't state on which platforms they are known to work. Having a dynamic object model and parsing from and to XML are must-haves for me. I'd also like to use reasoning, but I've been told it was rather computing-intensive, so that's only a nice-to-have. For all platforms mentioned, the question can be interpreted as Is it possible in theory (especially for J2ME I'm not sure) Are there libs that are known to work on those platforms? Is the performance on a mobile platform good enough for real world usage?

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• assistance with classifying tests

  - by amateur

  I have a .net c# library that I have created that I am currently creating some unit tests for. I am at present writing unit tests for a cache provider class that I have created. Being new to writing unit tests I have 2 questions These being: My cache provider class is the abstraction layer to my distributed cache - AppFabric. So to test aspects of my cache provider class such as adding to appfabric cache, removing from cache etc involves communicating with appfabric. Therefore the tests to test for such, are they still categorised as unit tests or integration tests? The above methods I am testing due to interacting with appfabric, I would like to time such methods. If they take longer than a specified benchmark, the tests have failed. Again I ask the question, can this performance benchmark test be classifed as a unit test? The way I have my tests set up I want to include all unit tests together, integration tests together etc, therefore I ask these questions that I would appreciate input on.

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• vector<vector<largeObject>> vs. vector<vector<largeObject>*> in c++

  - by Leif Andersen

  Obviously it will vary depending on the compiler you use, but I'm curious as to the performance issues when doing vector<vector<largeObject>> vs. vector<vector<largeObject>*>, especially in c++. In specific: let's say that you have the outer vector full, and you want to start inserting elements into first inner vector. How will that be stored in memory if the outer vector is just storing pointers, as apposed to storing the whole inner vector. Will the whole outer vector have to be moved to gain more space, or will the inner vector be moved (assuming that space wasn't pre-allocated), causing problems with the outer vector? Thank you

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• grails clean having issues

  - by hvgotcodes

  Im running grails 1.2 on win7. when i try to do grails clean it fails to remove some jars in my acegi plugin. after that failure, it complains about not finding the plugin descriptor. I am forced to remove all plugins from the disk manually and then run the app again to download them again. the particular jar in acegi is ant-contrib-xx.jar. has anyone seen this? as a further note, if i just delete the acegi directory after the initial failure it fails on a jar in another plugin. I dont know if Im having some sort of windows filesystem issue (I am coming from linux, forced to use win7 because intellij sucks on linux), or intellij is doing something, or what...

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• How can I dynamically inject code into event handlers in Delphi?

  - by mjustin

  For debugging / performance tests I would like to dynamically add logging code to all event handlers of components of a given type. For example, for all Dataset components located ona TDatamodule, I would like to add some code for the BeforeOpen and the AfterOpen event to store the start and end time and send a line to a logger with the elapsed time in the AfterOpen event. I would prefer to do this dynamically (no component subclassing), so that I can add this to all existing datamodules and forms with minimal effort only when needed. Iterating all components and filtering by their type is easy, but for the components which already have event handlers assigned, I need a way to store the existing event handlers, and assign a new modified event handler which first does the logging and then will invoke the original code which was already present. Is there a design pattern which can be applied, or even some example code which shows how to implement this in Delphi?

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• Is is better to store serialized data or raw html in mysql?

  - by Yegor

  I de-normalized my database, since the application was crawling otherwise, and Im storing a list of categories for each item in the DB as a raw html version, and simply echoing it out in my design. Each category is actually a link, which is include a tag. Naturally, this is abit of a pain, especially if I want to change the look of how the category links are displayed, since I gotta update all the old cached entries. What if I were to store this data as a serialized array instead, and simply unserialize it, and then apply formatting to it in php. Would there be a significant performance decrease over simply echoing out the raw html?

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• What is a .NET managed module?

  - by Abhijeet Patel

  I know it's a Windows PE32, but I also know that the unit of deployment in .NET is an assembly which in turn has a manifest and can be made up of multiple managed modules. My questions are : 1) How would you create multiple managed modules when building a project such as a class lib or a console app etc. 2) Is there a way to specify this to the compiler(via the project properties for example) to partition your source code files into multiple managed modules. If so what is the benefit of doing so? 3)Can managed modules span assemblies? 4)Are separate file created on disk when the source code is compiled or are these created in memory and directly embedded in an assembly?

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• Getting latest Subsonic builds

  - by Alex Yakunin

  I need the latest Subsonic build or build it by my own. Subsonic project web site shows the latest available version is Subsonic v3.0.0.3 released at July 15, 2009. Questions: Are there any later builds - e.g. maintained by community members? If so, how can I get the latest one? In worst case I'm ready to get the latest source code and try to build it by my own. Are there any instructions for this? Please note, that I'm not interested in almost 1 year old builds - I need a build based on the latest code for tests (LINQ, performance), ideally - compiled for .NET 4.0.

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• Good reasons why to not use XIB files?

  - by mystify

  Are there any good reasons why I should not use XIB / NIB files with an highly customized UI and extensive animations and super low memory footprint needs? As a beginner I started with XIB. Then I figured out I couldn't do just about everything in them. It started to get really hard to customize things the way I wanted them to be. So at the end, I threw all my XIBs away and did it all programmatically. So when someone asks me if XIB is good, I generally say: Yeah, if you want to make crappy boring interfaces and don't care too much about performance, go ahead. But what else could be a reason not to use XIB? Am I the only iPhone developer who prefers doing everything programmatically for this reasons?

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• MySQL triggers cannot update rows in same table the trigger is assigned to. Suggested workaround?

  - by Cory House

  MySQL doesn't currently support updating rows in the same table the trigger is assigned to since the call could become recursive. Does anyone have suggestions on a good workaround/alternative? Right now my plan is to call a stored procedure that performs the logic I really wanted in a trigger, but I'd love to hear how others have gotten around this limitation. Edit: A little more background as requested. I have a table that stores product attribute assignments. When a new parent product record is inserted, I'd like the trigger to perform a corresponding insert in the same table for each child record. This denormalization is necessary for performance. MySQL doesn't support this and throws: Can't update table 'mytable' in stored function/trigger because it is already used by statement which invoked this stored function/trigger. A long discussion on the issue on the MySQL forums basically lead to: Use a stored proc, which is what I went with for now. Thanks in advance!

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• Java vs Flash for webcam access

  - by Alfredo Palhares

  I will make a video chat website, but coming from PHP and Python for the web i have no experience with video steaming. What do you recommend? Java or Flash? What's more flexible ? I am thinking of even making a C++ server application for stream controlling with a PHP fronted. Since is going to be a high traffic website and performance is a must. Can you point to some direction? Any documentation? Framework?

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• Measuring daemon CPU utilization over a portion of it's wall clock run time

  - by WhirlWind

  I am dealing with a network-related daemon: it takes data in, processes it, and spits it out. I would like to increase the performance of this daemon by profiling it and reducing it's CPU utilization. I can do this easily on Linux with gprof. However, I would also like to use something like "time" to measure it's total CPU utilization over a period of time. If possible, I would like to time it over a period that is less than its total run time: thus, I would like to start the daemon, wait awhile, generate CPU statistics, stop generating them, then stop the daemon at some later time. The "time" command would work well for me, but it seems to require that I start and stop the daemon as a child of time. Is there a way to measure CPU utilization for only a portion of the daemon's wall clock time?

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• Maximizing the number of threads to fully utilize all available resources without hindering overall

  - by Matt

  Let's say I have to generate a bunch of result files, and I want to make it as fast as possible. Each result file is generated independently of any other result file; in fact, one could say that each result file is agnostic to every other result file. The resources used to generate each result file is also unique to each. How can I dynamically decide the optimal number of threads to run simultaneously in order to minimize the overall run time? Is my only option to write my own thread manager that watches performance counters and adjust accordingly or does there exists some solid classes that already accomplish this?

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• Append in Dom taking more time in IE than Firefox or any other browser.

  - by user307635

  Hi , I m working on .net framework 3.0 visual studio 08 and Testing it in IE8 and other browsers. Whenever I m inserting new elements in DOM (ex. 300 divs at one time) than I m getting the performance very slow in IE . Why?. If its a javascript debugging which is taking time or what else. Is it really true that IE Dom Append takes much time than any other browser. Please help me , I m stuck badly.

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• Endianness manipulation - is there a C library for this?

  - by Malvineous

  Hi all, With the sort of programs I write (working with raw file data) I often need functions to convert between big and little endian. Usually I write these myself (which is covered by many other posts here) but I'm not that keen on doing this for a number of reasons - the main one being lack of testing. I don't really want to spend ages testing my code in a big endian emulator, and often just omit the code for big endian machines altogether. I also would rather make use of faster functions provided by various compilers, while still keeping my programs cross-platform. The only things I can find are socket calls like htons() but they require different #include files on each platform, and some GPL code like this, however that particular file, while comprehensive, seems to miss out on some of the high performance functions provided by some compilers. So, does anyone know of a library (ideally just a .h file) that is well tested and provides a standard set of functions for dealing with endianness across many compilers and platforms?

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• Intercept windows open file

  - by HyLian

  Hello, I'm trying to make a small program that could intercept the open process of a file. The purpose is when an user double-click on a file in a given folder, windows would inform to the software, then it process that petition and return windows the data of the file. Maybe there would be another solution like monitoring Open messages and force Windows to wait while the program prepare the contents of the file. One application of this concept, could be to manage desencryption of a file in a transparent way to the user. In this context, the encrypted file would be on the disk and when the user open it ( with double-click on it or with some application such as notepad ), the background process would intercept that open event, desencrypt the file and give the contents of that file to the asking application. It's a little bit strange concept, it could be like "Man In The Middle" network concept, but with files instead of network packets. Thanks for reading.

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• Virtual and Physical Memory / OutOfMemoryException

  - by user417518

  Hi, I am working on a 64-bit .Net Windows Service application that essentially loads up a bunch of data for processing. While performing data volume testing, we were able to overwhelm the process and it threw an OutOfMemoryException (I do not have any performance statistics on the process when it failed.) I have a hard time believing that the process requested a chunk of memory that would have exceeded the allowable address space for the process since its running on a 64-bit machine. I do know that the process is running on a machine that is consistently in the neighborhood of 80%-90% physical memory usage. My question is: Can the CLR throw an OutOfMemoryException if the machine is critically low on available physical memory even though the process wouldn't exceed it's allowable amount of virtual memory? Thanks for your help!

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• WPF/.NET data access models - resource recommendations

  - by jasonk

  We're in the early design/prep phases of transferring/updating a rather large "legacy" 3 tier client-server app to a new version. We’re looking at doing WPF over Winforms as it appears to be the direction Microsoft is pushing development of the future and we’d like the maximize the life cycle/span of the apps. That said during the rewrite we’d like to make as many changes to our data access/presentation model to improve performance as much as possible up front as many. I’ve been doing some research along that vein but the vast majority of the resources I've found that discuss WPF focus only simple data tracking apps or focus on the very basics UI design/controls. The few items that even discuss data presentation are fairly elementary in depth. Are there any books/articles/recommended reading/other resources recommended for development related to large enterprise level business apps? Any “gotchas” that should/could be avoided? General advice to minimize the time underwater

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• SQL Server union selects built dynamically from list of words

  - by Adam Tuttle

  I need to count occurrence of a list of words across all records in a given table. If I only had 1 word, I could do this: select count(id) as NumRecs where essay like '%word%' But my list could be hundreds or thousands of words, and I don't want to create hundreds or thousands of sql requests serially; that seems silly. I had a thought that I might be able to create a stored procedure that would accept a comma-delimited list of words, and for each word, it would run the above query, and then union them all together, and return one huge dataset. (Sounds reasonable, right? But I'm not sure where to start with that approach...) Short of some weird thing with union, I might try to do something with a temp table -- inserting a row for each word and record count, and then returning select * from that temp table. If it's possible with a union, how? And does one approach have advantages (performance or otherwise) over the other?

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• Site images don't refresh after setting expired headers on .htaccess

  - by Miguel Hernandez

  I have a site that uses a CSS sprite for all the images. I set the .htaccess file to set the expired headers to a future time as they recommend to improve site performance. However, when I updated the sprite image none of my browsers on two different computers seem to fetch the new image. I deleted the .htaccess serveral times but no luck. I am sure this must be easy as pie to fix but right now I am out of options. Here is the code inside my .htaccess file: # CONFIGURE media caching # Header unset ETag FileETag None <FilesMatch "(?i)^.*\.(ico|flv|jpg|jpeg|png|gif|js|css)$"> Header unset Last-Modified Header set Expires "Fri, 21 Dec 2012 00:00:00 GMT" Header set Cache-Control "public, no-transform" </FilesMatch> <IfModule mod_deflate.c> <FilesMatch "\.(js|css)$"> SetOutputFilter DEFLATE </FilesMatch> </IfModule> Thanks!

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• What is a good Very-High level UI framework for JavaScript?

  - by Robert Gould

  I need to write a temporary Web-based graphical front-end for a custom server system. In this case performance and scalability aren't issues, since at most 10 people may check the system simultaneously. Also it should be PHP or Python (server) & JavaScript (client) (can't use Flex or Silverlight for very specific non-programming related issues). So I know I could use YUI or jQuery, but was wondering if there is something even more high-level that would say allow me to write such a little project within a few hours of work, and get done with it. Basically I want to be as lazy as possible (this is throw-away code anyways) and get the job done in as little time as possible. Any suggestions?

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• Play Shoutcast MP3 radio stream with Python?

  - by Zachary Brown

  I have managed to create an online radio station using Shoutcast and Sam Broadcaster. Now, I am wanting to build my own player for that radio station. I am not sure where to begin, I have googled, but no luck. I am using Python 2.6 on Microsoft Windows. I have managed to capture the stream and save it as an MP# on the hard disk, just not sure what to do with it next. I tried playback of the file, but it always pulls up errors. This is the code I have so far: import urllib target = open("broadcast.mp3") conn = urllib.urlopen("http://78.159.104.175:80") while True: target.write(con.read(5200)) Any help would be greatly appreciated!

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