Search Results

Search found 25579 results on 1024 pages for 'complex event processing'.

Page 754/1024 | < Previous Page | 750 751 752 753 754 755 756 757 758 759 760 761  | Next Page >

• Special technology needed for browser based chat?

  - by orokusaki

  On this post, I read about the usage of XMPP. Is this sort of thing necessary, and more importantly, my main question expanded: Can a chat server and client be built efficiently using only standard HTTP and browser technologies (such as PHP and JS, or RoR and JS, etc)? Or, is it best to stick with old protocols like XMPP find a way to integrate them with my application? I looked into CampFire via LiveHTTPHeaders and Firebug for about 5 minutes, and it appears to use Ajax to send a request which is never answered until another chat happens. Is this just CampFire opening a new thread on the server to listen for an update and then returning a response to the request when the thread hears an update? I noticed that they're requesting on a specific port (8043 if memory serves me) which makes me think that they're doing something more complex than just what I mentioned. Also, the URL requested started with /tcp/ which I found interesting. Note: I don't expect to ever have more than 150 users live-chatting in all the rooms combined at the same time. I understand that if I was building a hosted pay for chat service like CampFire with thousands of concurrent users, it would behoove me to invest time in researching special technologies vs trying to reinvent the wheel in a simple way in my app. Also, if you're going to do it with server polling, how often would you personally poll to maximize response without slamming the server?

  Read the article

• spring.net proxy factory with target type needs property virtual ?

  - by Vince

  Hi all, I'm creating spring.net proxy in code by using ProxyFactory object with ProxyTargetType to true to have a proxy on a non interfaced complex object. Proxying seems ok till i call a method on that object. The method references a public property and if this property is not virtual it's value is null. This doesn't happen if i use Spring.Aop.Framework.AutoProxy.InheritanceBasedAopConfigurer in spring config file but in this case i can't use this because spring context doesn't own this object. Is this normal to have such behavior or is there a tweak to perform what i want (proxying object virtual method without having to change properties virtual)? Note that i tried factory.AutoDetectInterfaces and factory.ProxyTargetAttributes values but doesn't help. My proxy creation code: public static T CreateMethodCallStatProxy<T>() { // Proxy factory ProxyFactory factory = new ProxyFactory(); factory.AddAdvice(new CallMonitorTrackerAdvice()); factory.ProxyTargetType = true; // Create instance factory.Target = Activator.CreateInstance<T>(); // Get proxy T proxiedClass = (T)factory.GetProxy(); return proxiedClass; } Thanks for your help

  Read the article

• Google Spreadsheet API problem: memory exceeded

  - by Robbert

  Hi guys, Don't know if anyone has experience with the Google Spreadsheets API or the Zend_GData classes but it's worth a go: When I try to insert a value in a 750 row spreadsheet, it takes ages and then throws an error that my memory limit (which is 128 MB!) was exceeded. I also got this when querying all records of this spreadsheet but this I can imaging because it's quite a lot of data. But why does this happen when inserting a row? That's not too complex, is it? Here's the code I used: public function insertIntoSpreadsheet($username, $password, $spreadSheetId, $data = array()) { $service = Zend_Gdata_Spreadsheets::AUTH_SERVICE_NAME; $client = Zend_Gdata_ClientLogin::getHttpClient($username, $password, $service); $client->setConfig(array( 'timeout' => 240 )); $service = new Zend_Gdata_Spreadsheets($client); if (count($data) == 0) { die("No valid data"); } try { $newEntry = $service->insertRow($data, $spreadSheetId); return true; } catch (Exception $e) { return false; } }

  Read the article

• Using SetParent to steal the main window of another process but keeping the message loops separate

  - by insta

  Background: My coworker and I are maintaining a million-line legacy application we inherited. Its frontend is written in VB6, and as we're devoting almost all of our resources to converting it to C#, we are looking for quick & dirty solutions to our specific problem. The application behaves in a plugin-ish manner. There are up to 20ish separate ActiveX controls that can be loaded at once in a grid-style layout. The problem is that the ActiveX controls do all of their processing on their own UI thread, and as a lot of it is blocking waiting on network access, the UI gets very soupy. When our hosting C# app loads these controls, it becomes unresponsive because of how many controls are chewing up UI resources doing nothing. To top it off, the controls are fragile and will crash at the slightest provocation. When they are hosted in the main C# app, it creates serious instability. The best my coworker and I have come up with so far is starting a process per ActiveX control. This process, which we call the proxy, is another winforms app. It uses named pipes to communicate with the hosting process. The hosting process creates a window, loads an ActiveX control of our choice (via some reflections & AxHost magic), and tells the main process what its window handle is via the named pipe. The main process uses a combination of SetParent, and SetWindowPos to move the proxy application into itself to emulate a plugin. Size updates are sent via the named pipe. This works well enough until the ActiveX application does some sort of lengthy process and we click around on the main window while it's working. For awhile the main window is responsive, but eventually it becomes unresponsive as the child window waits for its UI thread. How can we keep the child windows on their own complete thread while still getting the benefits of SetParent? (please let me know if anything isn't clear!)

  Read the article

• Problem in filtering records using Dataview (C#3.0)

  - by Newbie

  I have a data table . The data table is basically getting populated from excel sheet. And there are many excel sheets. Henceforth, I have written a utility method for accomplishing the same. Now in some of the excel sheets, there are date columns and in some it is not(only text/string). My function is populating the values properly into the datatable from the excell sheet. But there are many blank rows in the excel sheets some are filled with NULL , some with " ". So I need to filter those records (which are NULL or " " ) first before further processing. What I am after is to use a dataview and apply the filter over there. DataView dv = dataTable.DefaultView; dv.RowFilter = ColumnName + " <> ''"; Well by using metedata (GetOleDbSchemaTable(OleDbSchemaGuid.Columns, restrection)) I was able to get the column names from the excel sheet , so getting the column names is not an issue. But the problem is as I said in some Excel sheet there are date fileds some are not. So the Filter condition of the Dataview needs to be proper. If I apply the above logic, and if it encounters a Datafield, it is throwing error Cannot perform '<' operation on System.DateTime and System.String. Could you people please help me out? I need to filter columns(not known at compile time + their data types) which can have NULL and " " I am using C#3.0 Thanks

  Read the article

• How to keep your unit test Arrange step simple and still guarantee DDD invariants ?

  - by ian31

  DDD recommends that the domain objects should be in a valid state at any time. Aggregate roots are responsible for guaranteeing the invariants and Factories for assembling objects with all the required parts so that they are initialized in a valid state. However this seems to complicate the task of creating simple, isolated unit tests a lot. Let's assume we have a BookRepository that contains Books. A Book has : an Author a Category a list of Bookstores you can find the book in These are required attributes : a book has to have an author, a category and at least a book store you can buy the book from. There's likely to be a BookFactory since it is quite a complex object, and the Factory will initialize the Book with at least all the mentioned attributes. Now we want to unit test a method of the BookRepository that returns all the Books. To test if the method returns the books, we have to set up a test context (the Arrange step in AAA terms) where some Books are already in the Repository. If the only tool at our disposal to create Book objects is the Factory, the unit test now also uses and is dependent on the Factory and inderectly on Category, Author and Store since we need those objects to build up a Book and then place it in the test context. Would you consider this is a dependency in the same way that in a Service unit test we would be dependent on, say, a Repository that the Service would call ? How would you solve the problem of having to re-create a whole cluster of objects in order to be able to test a simple thing ? How would you break that dependency and get rid of all these attributes we don't need in our test ? By using mocks or stubs ? If you mock up things a Repository contains, what kind of mock/stubs would you use as opposed to when you mock up something the object under test talks to or consumes ?

  Read the article

• Browser performance when combining image resizing with animated movement

  - by Steve Reichgut

  I have been tasked with the job of converting a Flash animation into HTML. The animation is rather complex and requires the need to move multiple images (9) from location (x,y) to location (x2,y2) while simultaneously increasing the image size from 215px wide to 930px wide. While doing some initial testing of this animation with just 1-2 images, I noticed a lot of choppiness in FF handling of this animation. To try and isolate the problem, I removed the dynamic resizing of the animation and just moved it from point A to point B. What was interesting was that I saw the same behavior when simply moving a 930px image that was resized down to 215px (via the CSS width or inline width properties). When I try the same animation with a different image that is actually 215px wide, it performed smoothly. I then tried the same animation with the original 930px wide image (with no resizing) and it performed well also. This makes me wonder if the browser is having to "resize" the image down to 215px each time it is moved which is causing the choppiness. Is this a correct assumption? If so, is there any other way to optimize the animation to allow for simultaneous image resizing and image movement? Notes: 1) One optimization I have done is to position the images absolutely in order to minimize the reflow process. 2) I have tested the animation using both jQuery and the fX animation framework.

  Read the article

• mod_rewrite with location-based ACL in apache?

  - by Alexey

  Hi. There is a CGI-script that provides some API for our customers. Call syntax is: script.cgi?module=<str>&func=<str>[&other-options] The task is to make different authentiction rules for different modules. Optionally, it will be great to have nice URLs. My config: <VirtualHost *:80> DocumentRoot /var/www/example ServerName example.com # Global policy is to deny all <Location /> Order deny,allow Deny from all </Location> # doesn't work :( <Location /api/foo> Order deny,allow Deny from all Allow from 127.0.0.1 </Location> RewriteEngine On # The only allowed type of requests: RewriteRule /api/(.+?)/(.+) /cgi-bin/api.cgi?module=$1&func=$2 [PT] # All others are forbidden: RewriteRule /(.*) - [F] RewriteLog /var/log/apache2/rewrite.log RewriteLogLevel 5 ScriptAlias /cgi-bin /var/www/example <Directory /var/www/example> Options -Indexes AddHandler cgi-script .cgi </Directory> </VirtualHost> Well, I know that problem is order of processing that directives. <Location>s will be processed after mod_rewrite has done its work. But I believe there is a way to change it. :) Using of standard Order deny,allow + Allow from <something> directives is preferable because it's commonly used in other places like this. Thank you for your attention. :)

  Read the article

• JBoss Clustered Service that sends emails from txt file

  - by michael lucas

  I need a little push in the right direction. Here's my problem: I have to create an ultra-reliable service that sends email messages to clients whose addresses are stored in txt file on FTP server. Single txt file may contain unlimited number of entries. Most often the file contains about 300,000 entries. Service exposes interface with just two simple methods: TaskHandle sendEmails(String ftpFilePath); ProcessStatus checkProcessStatus(TaskHandle taskHandle); Method sendEmails() returns TaskHandle by which we can ask for ProcessStatus. For such a service to be reliable clustering is necessary. Processing single txt file might take a long time. Restarting one node in a cluster should have no impact on sending emails. We use JBoss AS 4.2.0 which comes with a nice HASingletonController that ensure one instance of service is running at given time. But once a fail-over happens, the second service should continue work from where the first one stopped. How can I share state between nodes in a cluster in such a way that leaves no possibility of sending some emails twice?

  Read the article

• _dl_runtime_resolve -- When do the shared objects get loaded in to memory?

  - by windfinder

  We have a message processing system with high performance demands. Recently we have noticed that the first message takes many times longer then subsequent messages. A bunch of transformation and message augmentation happens as this goes through our system, much of it done by way of external lib. I just profiled this issue (using callgrind), comparing a "run" of just one message with a "run" of many messages (providing a baseline of comparison). The main difference I see is the function "do_lookup_x" taking up a huge amount of time. Looking at the various calls to this function, they all seem to be called by the common function: _dl_runtime_resolve. Not sure what this function does, but to me this looks like the first time the various shared libraries are being used, and are then being loaded in to memory by the ld. Is this a correct assumption? That the binary will not load the shared libraries in to memory until they are being prepped for use, therefore we will see a massive slowdown on the first message, but on none of the subsequent? How do we go about avoiding this? Note: We operate on the microsecond scale.

  Read the article

• Evaluate or Show HTML using Javascript

  - by Anita

  Hello, I have this...portion of code in Javascript: var description = document.createElement('P'); description.className='rssBoxDescription'; description.innerHTML = itemTokens[2]; div.appendChild(description); I see that description gets the HTML value and displays as plain HTML coding not as HTML processing it shouldbe ... how to convert this HTML value in description to be appended to div element shown as HTML...which is not showing. Also it has value something like: <table><tr><td style="padding: 0 5px"><ahref="xttp://picasaweb.google.com/linktoimagepage"><imgtag style="border:1px solid #5C7FB9" s_rc="xttp://lh3.ggpht.com/imagepath" alt="image.jpg"/></a></td><td valign="top"><font color="#6B6B6B">Date: </font><font color="#333333">Jun 28, 2007 9:00 AM</font><br/><font color=\"#6B6B6B\">Number of Comments on Photo:</font><font color=\"#333333\">0</font><br/><p><ahref="xttp://picasaweb.google.com/linktoimage"><font color="#3964C2">View Photo</font></a></p></td></tr></table> Pls help Anita

  Read the article

• jQuery AJAX request (Rails 3) gets redirected and returns empty message body!

  - by elsurudo

  I'm trying to do a manual jQuery AJAX request the following way: $("#user_plan_id").change(function() { $("#plan_container").load('/plans/' + this.value); }); I have the "rails.js" file included in my header, and a "<%= csrf_meta_tag %". I see from my log that the request IS getting to the server (although without the authenticity token... does rails.js even do this?), but the response is a 302 (Found) rather than 200, and no data actually gets rendered. Any ideas? Edit: I now see that the first request redirects, and the proper partial gets rendered on the redirect. However, the 2nd response's body (on the client-side) is still empty. I'm guessing jQuery uses the first response and doesn't have a listener set up for the redirect. How do I get around this? Also, another note: the page doing the requesting is an HTTPS page. Here is what my log says: Started GET "/plans/221168073" for 127.0.0.1 at Tue Jun 15 01:24:06 -0400 2010 Processing by PlansController#show as HTML Parameters: {"id"=>"221168073"} DEPRECATION WARNING: Using #request_uri is deprecated. Use fullpath instead. (called from ensure_proper_protocol at /Users/ernestsurudo/Sites/vidfolia/vendor/plugins/ssl_requirement/lib/ssl_requirement.rb:57) Redirected to http://vidfolia.com/plans/221168073 Completed 302 Found in 1ms Perhaps it has something to do with the deprecation warning?

  Read the article

• how can we apply client side validation on fileupload control in ASP.NET to check filename contain s

  - by subodh

  I am working on ASP.NET3.5 platform. I have used a file upload control and a asp button to upload a file. Whenever i try to upload a file which contain special characterlike (file#&%.txt) it show crash and give the messeage Server Error in 'myapplication' Application. A potentially dangerous Request.Files value was detected from the client (filename="...\New Text &#.txt"). Description: Request Validation has detected a potentially dangerous client input value, and processing of the request has been aborted. This value may indicate an attempt to compromise the security of your application, such as a cross-site scripting attack. You can disable request validation by setting validateRequest=false in the Page directive or in the configuration section. However, it is strongly recommended that your application explicitly check all inputs in this case. Exception Details: System.Web.HttpRequestValidationException: A potentially dangerous Request.Files value was detected from the client (filename="...\New Text &#.txt"). Source Error: An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below. how can i prevent this crash using javascript at client side?

  Read the article

• Recommend me an architecture for this Facebook application

  - by andybaird

  Firstly, this question is subjective. There is not a right answer for this question and it really depends on what works for you. I'm hoping to use this thread as a breeding ground for ideas. I hope this is acceptable in this medium. I'm working on building a Facebook app that will be replacing an already popular app that gets ~50k hits a day. The original app is using a very typical LAMP setup with help from some Zend libraries for database layer extraction. For the most part the app worked well, except to solve a lot of issues I ended up fragmenting tables to speed things up. As a result, I couldn't do a lot of things with the app that I wanted to (namely any processing using aggregate data that needed to be returned quickly) So I'm starting to design plans for the next version of this application, and I have a whole bunch of new and cool features that I know would choke my current setup. I'm looking for technological recommendations of data storage methods that scale well. The database does not necessarily need to be relational, simple key/value storage would suffice (although at present time I know little to nothing about KV stores) What's your recommendation? How would you tackle this? I'd like to take a completely free approach to this -- although I am most familiar and comfortable using PHP, I want to leave all technical options open.

  Read the article

• How to hand-over a TCP listening socket with minimal downtime?

  - by Shtééf

  While this question is tagged EventMachine, generic BSD-socket solutions in any language are much appreciated too. Some background: I have an application listening on a TCP socket. It is started and shut down with a regular System V style init script. My problem is that it needs some time to start up before it is ready to service the TCP socket. It's not too long, perhaps only 5 seconds, but that's 5 seconds too long when a restart needs to be performed during a workday. It's also crucial that existing connections remain open and are finished normally. Reasons for a restart of the application are patches, upgrades, and the like. I unfortunately find myself in the position that, every once in a while, I need to do this kind of thing in production. The question: I'm looking for a way to do a neat hand-over of the TCP listening socket, from one process to another, and as a result get only a split second of downtime. I'd like existing connections / sockets to remain open and finish processing in the old process, while the new process starts servicing new connectinos. Is there some proven method of doing this using BSD-sockets? (Bonus points for an EventMachine solution.) Are there perhaps open-source libraries out there implementing this, that I can use as is, or use as a reference? (Again, non-Ruby and non-EventMachine solutions are appreciated too!)

  Read the article

• [BEGINNER] Javascript Pop Ups

  - by user566312

  Hey All, My boss has asked for a page that will not change to have two timed pop ups load. I have found code and edited it to what I had thought it should do, but it is only loading the last onLoad event. I am a designer and I have helped with making webpages, but Javascript is so far outside of what I can understand. I have already learned how to use the single pop up and spent a whiiile learning the timeouts, but I cannot seem to get it to work with multiple popup functions. If you have a moment, would you take a look? Thank you :) h <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>H's Page 1</title> <SCRIPT LANGUAGE="JavaScript"> <!-- Original: Ronnie T. Moore, Editor --> <!-- Web Site: The JavaScript Source --> <!-- This script and many more are available free online at --> <!-- The JavaScript Source!! http://javascript.internet.com --> <!-- Begin closetime = 3; // Close window after __ number of seconds? // 0 = do not close, anything else = number of seconds function Start1(URL, WIDTH, HEIGHT) { windowprops = "left=50,top=50,width=" + WIDTH + ",height=" + HEIGHT; preview = window.open(URL, "preview", windowprops); if (closetime) setTimeout("preview.close();", closetime*1000); } function doPopup1() { url = "http://www.google.com"; width = 1680; // width of window in pixels height = 1050; // height of window in pixels delay = 10; // time in seconds before popup opens timer = setTimeout("Start1(url, width, height)", delay*1000); } closetime = 3; // Close window after __ number of seconds? function Start2(URL, WIDTH, HEIGHT) { windowprops = "left=50,top=50,width=" + WIDTH + ",height=" + HEIGHT; preview = window.open(URL, "preview", windowprops); if (closetime) setTimeout("preview.close();", closetime*1000); } function doPopup2() { url = "http://www.yahoo.com"; width = 1680; // width of window in pixels height = 1050; // height of window in pixels delay = 5; // time in seconds before popup opens timer = setTimeout("Start2(url, width, height)", delay*1000); } // End --> </script> <!-- STEP TWO: Insert the onLoad event handler into your BODY tag --> <!-- Script Size: 1.27 KB --> </head> <body OnLoad="doPopup1(); doPopup2();"> <p>My page text.</p> <p>My page text.</p> <p>My page text.</p> <p>My page text.</p> </body> </html>

  Read the article

• ASP.NET CacheDependency out of ThreadPool

  - by Stephen

  In an async http handler, we add items to the ASP.NET cache, with dependencies on some files. If the async method executes on a thread from the ThreadPool, all is fine: AsyncResult result = new AsyncResult(context, cb, extraData); ThreadPool.QueueUserWorkItem(new WaitCallBack(DoProcessRequest), result); But as soon as we try to execute on a thread out of the ThreadPool: AsyncResult result = new AsyncResult(context, cb, extraData); Runner runner = new Runner(result); Thread thread = new Thread(new ThreadStart(runner.Run()); ... where Runner.Run just invokes DoProcessRequest, The dependencies do trigger right after the thread exits. I.e. the items are immediately removed from the cache, the reason being the dependencies. We want to use an out-of-pool thread because the processing might take a long time. So obviously something's missing when we create the thread. We might need to propagate the call context, the http context... Has anybody already encountered that issue? Note: off-the-shelf custom threadpools probably solve this. Writing our own threadpool is probably a bad idea (think NIH syndrom). Yet I'd like to understand this in details, though.

  Read the article

• Saving "heavy" image to PDF in MATLAB - rendering problem

  - by yuk

  I generate a figure in MATLAB with lot amount of points (100000+) and want to save it into a PDF file. With zbuffer or painters renderer I've got very large and slowly opened file (over 4 Mb) - all points are in vector format. Using OpenGL renderer rasterize the figure in PDF, ok for the plot, but not good for text labels. The file size is about 150 Kb. Try this simplified code, for example: x=linspace(1,10,100000); y=sin(x)+randn(size(x)); plot(x,y,'.') set(gcf,'Renderer','zbuffer') print -dpdf -r300 testpdf_zb set(gcf,'Renderer','painters') print -dpdf -r300 testpdf_pa set(gcf,'Renderer','opengl') print -dpdf -r300 testpdf_op The actual figure is much more complex with several axes and different types of plots. Is there a way to rasterize the figure, but keep text labels as vectors? Another problem with OpenGL is that is does not work in terminal mode (-nosplash -nodesktop) under Mac OSX. Looks like OpenGL is not supported. I have to use terminal mode for automation. The MATLAB version I run is 2007b. Mac OSX server 10.4.

  Read the article

• How would i down-sample a .wav file then reconstruct it using nyquist? - in MATLAB

  - by Andrew

  This is all done in MATLAB 2010 My objective is to show the results of: undersampling, nyquist rate/ oversampling First i need to downsample the .wav file to get an incomplete/ or impartial data stream that i can then reconstuct. Heres the flow chart of what im going to be doing So the flow is analog signal - sampling analog filter - ADC - resample down - resample up - DAC - reconstruction analog filter what needs to be achieved: F= Frequency F(Hz=1/s) E.x. 100Hz = 1000 (Cyc/sec) F(s)= 1/(2f) Example problem: 1000 hz = Highest frequency 1/2(1000hz) = 1/2000 = 5x10(-3) sec/cyc or a sampling rate of 5ms This is my first signal processing project using matlab. what i have so far. % Fs = frequency sampled (44100hz or the sampling frequency of a cd) [test,fs]=wavread('test.wav'); % loads the .wav file left=test(:,1); % Plot of the .wav signal time vs. strength time=(1/44100)*length(left); t=linspace(0,time,length(left)); plot(t,left) xlabel('time (sec)'); ylabel('relative signal strength') **%this is were i would need to sample it at the different frequecys (both above and below and at) nyquist frequency.*I think.*** soundsc(left,fs) % shows the resaultant audio file , which is the same as original ( only at or above nyquist frequency however) Can anyone tell me how to make it better, and how to do the sampling at verious frequencies?

  Read the article

• Analyze log files from many languages using a single tool. And recommendations of logging frameworks

  - by Binary255

  We have a system build on lots of languages. The ones we are interested in logging, in order of priority, are: C/C++ PHP C# Bash Java Wish list: If it is possible, we would like logging to be achieved from the above languages in such a way that we may use a single log viewing tool for all of them. Ideally they would be in the same format, but next to that in as few formats as possible and readable from as many log file viewers as possible. If it is possible logging to a single log file or a set of log files would be nice. With a possibility to filter based on the source language that is being logged. We would like to copy the log files (or should be log to a database and copy it instead?) from multiple servers to a single location. So that we can analyze the log files from many servers at the same time (to see if any of our servers execute a certain piece legacy code for example). Being able to change logging level at runtime would be nice. Thank you for reading! It's quite a complex problem, I hope someone has wrestled with it before and has some valuable information!

  Read the article

• Catching / blocking SIGINT during system call

  - by danben

  I've written a web crawler that I'd like to be able to stop via the keyboard. I don't want the program to die when I interrupt it; it needs to flush its data to disk first. I also don't want to catch KeyboardInterruptedException, because the persistent data could be in an inconsistent state. My current solution is to define a signal handler that catches SIGINT and sets a flag; each iteration of the main loop checks this flag before processing the next url. However, I've found that if the system happens to be executing socket.recv() when I send the interrupt, I get this: ^C Interrupted; stopping... // indicates my interrupt handler ran Traceback (most recent call last): File "crawler_test.py", line 154, in <module> main() ... File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/socket.py", line 397, in readline data = recv(1) socket.error: [Errno 4] Interrupted system call and the process exits completely. Why does this happen? Is there a way I can prevent the interrupt from affecting the system call?

  Read the article

• Getting a handle on GIS math, where do I start?

  - by Joshua

  I am in charge of a program that is used to create a set of nodes and paths for consumption by an autonomous ground vehicle. The program keeps track of the locations of all items in its map by indicating the item's position as being x meters north and y meters east of an origin point of 0,0. In the real world, the vehicle knows the location of the origin's lat and long, as it is determined by a dgps system and is accurate down to a couple centimeters. My program is ignorant of any lat long coordinates. It is one of my goals to modify the program to keep track of lat long coords of items in addition to an origin point and items' x,y position in relation to that origin. At first blush, it seems that I am going to modify the program to allow the lat long coords of the origin to be passed in, and after that I desire that the program will automatically calculate the lat long of every item currently in a map. From what I've researched so far, I believe that I will need to figure out the math behind converting to lat long coords from a UTM like projection where I specify the origin points and meridians etc as opposed to whatever is defined already for UTM. I've come to ask of you GIS programmers, am I on the right track? It seems to me like there is so much to wrap ones head around, and I'm not sure if the answer isn't something as simple as, "oh yea theres a conversion from meters to lat long, here" Currently, due to the nature of DGPS, the system really doesn't need to care about locations more than oh, what... 40 km? radius away from the origin. Given this, and the fact that I need to make sure that the error on my coordinates is not greater than .5 meters, do I need anything more complex than a simple lat/long to meters conversion constant? I'm knee deep in materials here. I could use some pointers about what concepts to research. Thanks much!

  Read the article

• DataSets to POCOs - an inquiry regarding DAL architecture

  - by alexsome

  Hello all, I have to develop a fairly large ASP.NET MVC project very quickly and I would like to get some opinions on my DAL design to make sure nothing will come back to bite me since the BL is likely to get pretty complex. A bit of background: I am working with an Oracle backend so the built-in LINQ to SQL is out; I also need to use production-level libraries so the Oracle EF provider project is out; finally, I am unable to use any GPL or LGPL code (Apache, MS-PL, BSD are okay) so NHibernate/Castle Project are out. I would prefer - if at all possible - to avoid dishing out money but I am more concerned about implementing the right solution. To summarize, there are my requirements: Oracle backend Rapid development (L)GPL-free Free I'm reasonably happy with DataSets but I would benefit from using POCOs as an intermediary between DataSets and views. Who knows, maybe at some point another DAL solution will show up and I will get the time to switch it out (yeah, right). So, while I could use LINQ to convert my DataSets to IQueryable, I would like to have a generic solution so I don't have to write a custom query for each class. I'm tinkering with reflection right now, but in the meantime I have two questions: Are there any problems I overlooked with this solution? Are there any other approaches you would recommend to convert DataSets to POCOs? Thanks in advance.

  Read the article

• Remove Empty Attributes from XML

  - by er4z0r

  Hi, I have a buggy xml that contains empty attributes and I have a parser that coughs on empty attributes. I have no control over the generation of the xml nor over the parser that coughs on empty attrs. So what I want to do is a pre-processing step that simply removes all empty attributes. I have managed to find the empty attribus, but now I don't know how to remove them: XPathFactory xpf = XPathFactory.newInstance(); XPath xpath = xpf.newXPath(); XPathExpression expr = xpath.compile("//@*"); Object result = expr.evaluate(d, XPathConstants.NODESET); if (result != null) { NodeList nodes = (NodeList) result; for(int node=0;node<nodes.getLength();node++) { Node n = nodes.item(node); if(isEmpty(n.getTextContent())) { this.log.warn("Found empty attribute declaration "+n.toString()); NamedNodeMap parentAttrs = n.getParentNode().getAttributes(); parentAttrs.removeNamedItem(n.getNodeName()); } } } This code gives me a NPE when accessing n.getParentNode().getAttributes(). But how can I remove the empty attribute from an element, when I cannot access the element?

  Read the article

• Erlang ODBC parameter query with null parameters

  - by Schlomer

  Is it possible to pass null values to parameter queries? For example Sql = "insert into TableX values (?,?)". Params = [{sql_integer, [Val1]}, {sql_float, [Val2]}]. % Val2 may be a float, or it may be the atom, undefined odbc:param_query(OdbcRef, Sql, Params). Now, of course odbc:param_query/3 is going to complain if Val2 is undefined when trying to match to a sql_float, but my question is... Is it possible to use a parameterized query, such as: Sql = "insert into TableY values (?,?,?,?,?,?,?,?,?)". with any null parameters? I have a use case where I am dumping a large number of real-time data into a database by either inserting or updating. Some of the tables I am updating have a dozen or so nullable fields, and I do not have a guarantee that all of the data will be there. Concatenating a SQL together for each query, checking for null values seems complex, and the wrong way to do it. Having a parameterized query for each permutation is simply not an option. Any thoughts or ideas would be fantastic! Thank you!

  Read the article

< Previous Page | 750 751 752 753 754 755 756 757 758 759 760 761  | Next Page >