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• How can I debug this web service http handler?

  - by baron

  Hello everyone, I am building a Httphandler following these instructions here It manipulates HTTP POST and HTTP GET. I have a client with two buttons two POST and GET. After i've tested and happy everythings working I move it from localhost to IIS. Now when I do this I get an exception in the POST handler code. How on earth can I debug this code line by line? I managed to do this awhile ago, I thought it was by attaching to process but I can't work it out. I can emulate GET just by typing address in browser, post im not sure about. I've tried telnetting and sending it from there but haven't had any luck.

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• Initializing new instances of a class in a loop, how can I persist an assignment to an event handler

  - by Pydroid

  This is a follow on question from http://stackoverflow.com/questions/3020960/why-is-my-prototype-function-not-returning-the-property-of-the-instance $.getJSON(myjson, function(data) { var json = data; for (i in json) { juuvies[i] = new Juuvy(i,json[i], font, keyfontsize, valfontsize, orbcol, orbkeycol, orbvalcol, paper); juuvies[i].juuv_it(); var mykey = juuvies[i].init_nodes(); juuvies[i].orb.node.onmouseover = function() { console.log(mykey);}; } }); And my init_nodes function, Juuvy.prototype.init_nodes = function() { return this.key; } At this point of time, I get only the last key in the loop, instead of a unique pass each time. Is there a way I can persist the assignment for the event handler?

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• Why and How to avoid Event Handler memory leaks ?

  - by gillyb

  Hey There, I just came to realize, by reading some questions and answers on StackOverflow, that adding event handlers using += in C# (or i guess, other .net languages) can cause common memory leaks... I have used event handlers like this in the past many times, and never realized that they can cause, or have caused, memory leaks in my applications. How does this work (meaning, why does this actually cause a memory leak) ? How can I fix this problem ? Is using -= to the same event handler enough ? Are there common design patterns or best practices for handling situations like this ? Example : How am I supposed to handle an application that has many different threads, using many different event handlers to raise several events on the UI ? Are there any good and simple ways to monitor this efficiently in an already built big application ? Thanks in advance!

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• How can I close the output stream after a jsp has been included.

  - by stu

  I have a webpage that makes an ajax call to get some data. That data takes a long time to calculate, so what I did was the first ajax server call returns "loading..." and then the thread goes on to calculate the data and store it in a cache. meanwhile the client javascript checks back every few seconds with another ajax call to see if the cache has been loaded yet. Here's my problem, and it might not be a problem. After the initial ajax to the server call, I do a ...getServletContext().getRequestDispatcher(jsppath).include(request, response); then I use that thread to do the calculations. I don't mind tying up the webserver thread with this, but I want the browser to get the response and not wait for the server to close the socket. I can't tell if the server is closing the socket after the include, but I'm guessing it's not. So how can I forcibly close the stream after I've written out my response, before starting my long calculations? I tried o = response.getOutputStream(); o.close(); but I get an illegal state exception saying that the output stream has already been gotten (presumably by the jsp I'm including) So my qestions: 1) is the webserver closing the socket (I'm guessing not, because you could always include another jsp) 2) if it is as I assume not closing the socket, how do I do that?

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• Is pthread_spin_trylock safe inside of sigsegv handler of multithreaded application?

  - by TWMouton

  I am trying to implement a handler that on SIGSEGV will collect some information such as process-id, thread-id and a backtrace and write this information to a file/pipe/socket. The problem lies in that there is the (probably pretty high) possibility that if one thread experienced a SIGSEGV that the others will shortly follow. If two threads happen to make it to the bit of code where they're writing their report out at the same time then they'll interleave their writing (to the same file). I know that I should only be using async-signal-safe functions as detailed in signal(7) I also have seen at least two cases here and video linked in top answer here where others have used pthread_spin_trylock to get around this problem. Is this a safe way to prevent the above problem?

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• Using an alternate JSON Serializer in ASP.NET Web API

  - by Rick Strahl

  The new ASP.NET Web API that Microsoft released alongside MVC 4.0 Beta last week is a great framework for building REST and AJAX APIs. I've been working with it for quite a while now and I really like the way it works and the complete set of features it provides 'in the box'. It's about time that Microsoft gets a decent API for building generic HTTP endpoints into the framework. DataContractJsonSerializer sucks As nice as Web API's overall design is one thing still sucks: The built-in JSON Serialization uses the DataContractJsonSerializer which is just too limiting for many scenarios. The biggest issues I have with it are: No support for untyped values (object, dynamic, Anonymous Types) MS AJAX style Date Formatting Ugly serialization formats for types like Dictionaries To me the most serious issue is dealing with serialization of untyped objects. I have number of applications with AJAX front ends that dynamically reformat data from business objects to fit a specific message format that certain UI components require. The most common scenario I have there are IEnumerable query results from a database with fields from the result set rearranged to fit the sometimes unconventional formats required for the UI components (like jqGrid for example). Creating custom types to fit these messages seems like overkill and projections using Linq makes this much easier to code up. Alas DataContractJsonSerializer doesn't support it. Neither does DataContractSerializer for XML output for that matter. What this means is that you can't do stuff like this in Web API out of the box:public object GetAnonymousType() { return new { name = "Rick", company = "West Wind", entered= DateTime.Now }; } Basically anything that doesn't have an explicit type DataContractJsonSerializer will not let you return. FWIW, the same is true for XmlSerializer which also doesn't work with non-typed values for serialization. The example above is obviously contrived with a hardcoded object graph, but it's not uncommon to get dynamic values returned from queries that have anonymous types for their result projections. Apparently there's a good possibility that Microsoft will ship Json.NET as part of Web API RTM release.  Scott Hanselman confirmed this as a footnote in his JSON Dates post a few days ago. I've heard several other people from Microsoft confirm that Json.NET will be included and be the default JSON serializer, but no details yet in what capacity it will show up. Let's hope it ends up as the default in the box. Meanwhile this post will show you how you can use it today with the beta and get JSON that matches what you should see in the RTM version. What about JsonValue? To be fair Web API DOES include a new JsonValue/JsonObject/JsonArray type that allow you to address some of these scenarios. JsonValue is a new type in the System.Json assembly that can be used to build up an object graph based on a dictionary. It's actually a really cool implementation of a dynamic type that allows you to create an object graph and spit it out to JSON without having to create .NET type first. JsonValue can also receive a JSON string and parse it without having to actually load it into a .NET type (which is something that's been missing in the core framework). This is really useful if you get a JSON result from an arbitrary service and you don't want to explicitly create a mapping type for the data returned. For serialization you can create an object structure on the fly and pass it back as part of an Web API action method like this:public JsonValue GetJsonValue() { dynamic json = new JsonObject(); json.name = "Rick"; json.company = "West Wind"; json.entered = DateTime.Now; dynamic address = new JsonObject(); address.street = "32 Kaiea"; address.zip = "96779"; json.address = address; dynamic phones = new JsonArray(); json.phoneNumbers = phones; dynamic phone = new JsonObject(); phone.type = "Home"; phone.number = "808 123-1233"; phones.Add(phone); phone = new JsonObject(); phone.type = "Home"; phone.number = "808 123-1233"; phones.Add(phone); //var jsonString = json.ToString(); return json; } which produces the following output (formatted here for easier reading):{ name: "rick", company: "West Wind", entered: "2012-03-08T15:33:19.673-10:00", address: { street: "32 Kaiea", zip: "96779" }, phoneNumbers: [ { type: "Home", number: "808 123-1233" }, { type: "Mobile", number: "808 123-1234" }] } If you need to build a simple JSON type on the fly these types work great. But if you have an existing type - or worse a query result/list that's already formatted JsonValue et al. become a pain to work with. As far as I can see there's no way to just throw an object instance at JsonValue and have it convert into JsonValue dictionary. It's a manual process. Using alternate Serializers in Web API So, currently the default serializer in WebAPI is DataContractJsonSeriaizer and I don't like it. You may not either, but luckily you can swap the serializer fairly easily. If you'd rather use the JavaScriptSerializer built into System.Web.Extensions or Json.NET today, it's not too difficult to create a custom MediaTypeFormatter that uses these serializers and can replace or partially replace the native serializer. Here's a MediaTypeFormatter implementation using the ASP.NET JavaScriptSerializer:using System; using System.Net.Http.Formatting; using System.Threading.Tasks; using System.Web.Script.Serialization; using System.Json; using System.IO; namespace Westwind.Web.WebApi { public class JavaScriptSerializerFormatter : MediaTypeFormatter { public JavaScriptSerializerFormatter() { SupportedMediaTypes.Add(new System.Net.Http.Headers.MediaTypeHeaderValue("application/json")); } protected override bool CanWriteType(Type type) { // don't serialize JsonValue structure use default for that if (type == typeof(JsonValue) || type == typeof(JsonObject) || type== typeof(JsonArray) ) return false; return true; } protected override bool CanReadType(Type type) { if (type == typeof(IKeyValueModel)) return false; return true; } protected override System.Threading.Tasks.Taskobject OnReadFromStreamAsync(Type type, System.IO.Stream stream, System.Net.Http.Headers.HttpContentHeaders contentHeaders, FormatterContext formatterContext) { var task = Taskobject.Factory.StartNew(() = { var ser = new JavaScriptSerializer(); string json; using (var sr = new StreamReader(stream)) { json = sr.ReadToEnd(); sr.Close(); } object val = ser.Deserialize(json,type); return val; }); return task; } protected override System.Threading.Tasks.Task OnWriteToStreamAsync(Type type, object value, System.IO.Stream stream, System.Net.Http.Headers.HttpContentHeaders contentHeaders, FormatterContext formatterContext, System.Net.TransportContext transportContext) { var task = Task.Factory.StartNew( () = { var ser = new JavaScriptSerializer(); var json = ser.Serialize(value); byte[] buf = System.Text.Encoding.Default.GetBytes(json); stream.Write(buf,0,buf.Length); stream.Flush(); }); return task; } } } Formatter implementation is pretty simple: You override 4 methods to tell which types you can handle and then handle the input or output streams to create/parse the JSON data. Note that when creating output you want to take care to still allow JsonValue/JsonObject/JsonArray types to be handled by the default serializer so those objects serialize properly - if you let either JavaScriptSerializer or JSON.NET handle them they'd try to render the dictionaries which is very undesirable. If you'd rather use Json.NET here's the JSON.NET version of the formatter:// this code requires a reference to JSON.NET in your project #if true using System; using System.Net.Http.Formatting; using System.Threading.Tasks; using System.Web.Script.Serialization; using System.Json; using Newtonsoft.Json; using System.IO; using Newtonsoft.Json.Converters; namespace Westwind.Web.WebApi { public class JsonNetFormatter : MediaTypeFormatter { public JsonNetFormatter() { SupportedMediaTypes.Add(new System.Net.Http.Headers.MediaTypeHeaderValue("application/json")); } protected override bool CanWriteType(Type type) { // don't serialize JsonValue structure use default for that if (type == typeof(JsonValue) || type == typeof(JsonObject) || type == typeof(JsonArray)) return false; return true; } protected override bool CanReadType(Type type) { if (type == typeof(IKeyValueModel)) return false; return true; } protected override System.Threading.Tasks.Taskobject OnReadFromStreamAsync(Type type, System.IO.Stream stream, System.Net.Http.Headers.HttpContentHeaders contentHeaders, FormatterContext formatterContext) { var task = Taskobject.Factory.StartNew(() = { var settings = new JsonSerializerSettings() { NullValueHandling = NullValueHandling.Ignore, }; var sr = new StreamReader(stream); var jreader = new JsonTextReader(sr); var ser = new JsonSerializer(); ser.Converters.Add(new IsoDateTimeConverter()); object val = ser.Deserialize(jreader, type); return val; }); return task; } protected override System.Threading.Tasks.Task OnWriteToStreamAsync(Type type, object value, System.IO.Stream stream, System.Net.Http.Headers.HttpContentHeaders contentHeaders, FormatterContext formatterContext, System.Net.TransportContext transportContext) { var task = Task.Factory.StartNew( () = { var settings = new JsonSerializerSettings() { NullValueHandling = NullValueHandling.Ignore, }; string json = JsonConvert.SerializeObject(value, Formatting.Indented, new JsonConverter[1] { new IsoDateTimeConverter() } ); byte[] buf = System.Text.Encoding.Default.GetBytes(json); stream.Write(buf,0,buf.Length); stream.Flush(); }); return task; } } } #endif   One advantage of the Json.NET serializer is that you can specify a few options on how things are formatted and handled. You get null value handling and you can plug in the IsoDateTimeConverter which is nice to product proper ISO dates that I would expect any Json serializer to output these days. Hooking up the Formatters Once you've created the custom formatters you need to enable them for your Web API application. To do this use the GlobalConfiguration.Configuration object and add the formatter to the Formatters collection. Here's what this looks like hooked up from Application_Start in a Web project:protected void Application_Start(object sender, EventArgs e) { // Action based routing (used for RPC calls) RouteTable.Routes.MapHttpRoute( name: "StockApi", routeTemplate: "stocks/{action}/{symbol}", defaults: new { symbol = RouteParameter.Optional, controller = "StockApi" } ); // WebApi Configuration to hook up formatters and message handlers // optional RegisterApis(GlobalConfiguration.Configuration); } public static void RegisterApis(HttpConfiguration config) { // Add JavaScriptSerializer formatter instead - add at top to make default //config.Formatters.Insert(0, new JavaScriptSerializerFormatter()); // Add Json.net formatter - add at the top so it fires first! // This leaves the old one in place so JsonValue/JsonObject/JsonArray still are handled config.Formatters.Insert(0, new JsonNetFormatter()); } One thing to remember here is the GlobalConfiguration object which is Web API's static configuration instance. I think this thing is seriously misnamed given that GlobalConfiguration could stand for anything and so is hard to discover if you don't know what you're looking for. How about WebApiConfiguration or something more descriptive? Anyway, once you know what it is you can use the Formatters collection to insert your custom formatter. Note that I insert my formatter at the top of the list so it takes precedence over the default formatter. I also am not removing the old formatter because I still want JsonValue/JsonObject/JsonArray to be handled by the default serialization mechanism. Since they process in sequence and I exclude processing for these types JsonValue et al. still get properly serialized/deserialized. Summary Currently DataContractJsonSerializer in Web API is a pain, but at least we have the ability with relatively limited effort to replace the MediaTypeFormatter and plug in our own JSON serializer. This is useful for many scenarios - if you have existing client applications that used MVC JsonResult or ASP.NET AJAX results from ASMX AJAX services you can plug in the JavaScript serializer and get exactly the same serializer you used in the past so your results will be the same and don't potentially break clients. JSON serializers do vary a bit in how they serialize some of the more complex types (like Dictionaries and dates for example) and so if you're migrating it might be helpful to ensure your client code doesn't break when you switch to ASP.NET Web API. Going forward it looks like Microsoft is planning on plugging in Json.Net into Web API and make that the default. I think that's an awesome choice since Json.net has been around forever, is fast and easy to use and provides a ton of functionality as part of this great library. I just wish Microsoft would have figured this out sooner instead of now at the last minute integrating with it especially given that Json.Net has a similar set of lower level JSON objects JsonValue/JsonObject etc. which now will end up being duplicated by the native System.Json stuff. It's not like we don't already have enough confusion regarding which JSON serializer to use (JavaScriptSerializer, DataContractJsonSerializer, JsonValue/JsonObject/JsonArray and now Json.net). For years I've been using my own JSON serializer because the built in choices are both limited. However, with an official encorsement of Json.Net I'm happily moving on to use that in my applications. Let's see and hope Microsoft gets this right before ASP.NET Web API goes gold.© Rick Strahl, West Wind Technologies, 2005-2012Posted in Web Api  AJAX  ASP.NET   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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• How to change mod_rewrite to avoid {REQUEST_FILENAME} in order to get around 255 character URL limit?

  - by Jeremy Reimer

  According to this answer: max length of url 257 characters for mod_rewrite? there is a maximum 255 character hard limit based on the file system for using mod_rewrite. According to the accepted answer, there are two solutions: Change the URL format of your application to a max of 255 characters between each slash. Move the Rewrite rules into the apache virtual host config and remove the REQUEST_FILENAME. I cannot use the first method, so I am trying to figure out the second. I have put the Rewrite rules into the Apache virtual host config as requested. However I cannot figure out how to remove the REQUEST_FILENAME and still have my web application framework (Dragonfly) still work. Here is the portion of the rewrite rules that I moved from .htaccess into the virtual host config file of Apache: RewriteCond %{REQUEST_FILENAME} !-d RewriteCond %{REQUEST_FILENAME} !-l RewriteCond %{REQUEST_FILENAME} !-f [OR] # if don't want Dragonfly to process html files comment # out the line below (you may need to remove the [OR] above too). RewriteCond %{REQUEST_FILENAME} \.(html|nl)$ # Main URL rewriting. RewriteRule (.*) index.cgi?$1 [L,QSA] I've tried removing {REQUEST_FILENAME} and it just breaks the framework in various ways. How do I rewrite this without using {REQUEST_FILENAME}?

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• Tool for making fn-x buttons work? Archlinux, handler.sh

  - by data_jepp

  This just seems like such a normal thing to work. I know that this works out of the box on Ubuntu. But not in Archlinux. I would like to think that there is a tool in existence that would use acpi_listen to create a step by step way to enable all of the fn buttons on the keyboard. Everything works expect fn-F10(mute), fn-F11(s-down), fn-F12(s-up). How can I make the sound buttons work?

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• Debugging nginx URL rewrite: How do I figure out where the problem is?

  - by pjmorse

  I have a specific URL pattern on a site which needs to be redirected to the HTTPS version. This is a Django site; Nginx checks each URL in memcached, and if it doesn't find a cached version it proxies the request to Apache/mod_python for Django to render the page. The relevant configuration block is rewrite ^/certificate https://mysite.com/certificate ; rewrite ^/([a-zA-Z]{2})/certificate https://mysite.com/certificate ; ...and it doesn't appear to be working at all. Nginx is: $ nginx -V nginx version: nginx/0.7.65 built by gcc 4.2.4 (Ubuntu 4.2.4-1ubuntu4) TLS SNI support disabled configure arguments: --prefix=/usr/local/nginx --pid-path=/var/run/nginx.pid --with-http_gzip_static_module --with-http_ssl_module How can I figure out if the problem is my patterns not matching, or a more obscure configuration problem? (The site is localized to three languages, and the localization is in the URL string, e.g. /US/news/, /DE/about, etc. It tracks localization in the session as well, defaulting to US, so if you just requested /news Django will rewrite to /US/news unless the user has a cookie indicating they're using a different localization. Django handles this, though, not Nginx.)

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• Cloned Centos 6.4 websrver for test purpose. Virtual host, .htaccess, redirecting url issue

  - by Shogoot

  I see similar questions, but not my exact challenge. What I have done so far I cloned a prod server over to a vmware to use it as a test server for new functionality I'm going to write. I'm not a sysadmin by trade, but I'm new to this company and I have to do some thing that are outside of my comfort zone (thats a good thing :) ) The prod server has 2 sites on it s1.com and s2.com. In /html/s1/, /html/s2/ there's an .htaccess file under each s*/. Looking like this: RewriteEngine ON RewriteBase / RewriteCond %{QUERY_STRING} id=([0-9]+) RewriteRule ^.* %1.htm RewriteCond %{QUERY_STRING} page=modules/checkout RewriteRule ^.* order.php RewriteCond %{QUERY_STRING} page=pages/sidekart RewriteRule ^.* pages/sidekart.htm The issue is that s1 has a lot of pages that really belongs under a third domain s3, the rule in line 4 and 5 redirects them to /html/s1/. An example of such URL is: s3.com/?page=modules/product&id=521614 I'm trying then to get those URLs (without modifying the URL) to redirect to s3's /html/s3/ server structure, which I set up making a new virtualhost s3 in test servers httpd.conf with a test3.com as servername and changing the other sites to tests1.com and tests2.com, and adding .htaccess also to this s3 root directory, and making a html/s3/ directory structure I populated with an index.html, etc. But, when I take the same URL (s3.com/?page=modules/product&id=521614) changing it to tests3.com/?page=modules/product&id=521614, I get s1's index page showing up in my browser. I've poked around about a day now and i cant figure out why this happens.

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• C# Serialization lock out

  - by Greycrow

  When I try to Serialize a class to an xml file I get the exception: The process cannot access the file 'C:\settings.xml' because it is being used by another process. Settings currentSettings = new Settings(); public void LoadSettings() { //Load Settings from XML file try { Stream stream = File.Open("settings.xml", FileMode.Open); XmlSerializer s = new XmlSerializer(typeof(Settings)); currentSettings = (Settings)s.Deserialize(stream); stream.Close(); } catch //Can't read XML - use default settings { currentSettings.Name = GameSelect.Items[0].ToString(); currentSettings.City = MapSelect.Items[0].ToString(); currentSettings.Country = RaceSelect.Items[0].ToString(); } } public void SaveSettings() { //Save Settings to XML file try { Stream stream = File.Open("settings.xml", FileMode.Create); XmlSerializer x = new XmlSerializer(typeof(Settings)); x.Serialize(stream, currentSettings); stream.Close(); } catch { MessageBox.Show("Unable to open XML File - File in use by other process"); } It appears that when I Deserialize it locks the file for writing back, even if I closed the stream. Thanks in advance.

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• Raising C# events with an extension method - is it bad?

  - by Kyralessa

  We're all familiar with the horror that is C# event declaration. To ensure thread-safety, the standard is to write something like this: public event EventHandler SomethingHappened; protected virtual void OnSomethingHappened(EventArgs e) { var handler = SomethingHappened; if (handler != null) handler(this, e); } Recently in some other question on this board (which I can't find now), someone pointed out that extension methods could be used nicely in this scenario. Here's one way to do it: static public class EventExtensions { static public void RaiseEvent(this EventHandler @event, object sender, EventArgs e) { var handler = @event; if (handler != null) handler(sender, e); } static public void RaiseEvent<T>(this EventHandler<T> @event, object sender, T e) where T : EventArgs { var handler = @event; if (handler != null) handler(sender, e); } } With these extension methods in place, all you need to declare and raise an event is something like this: public event EventHandler SomethingHappened; void SomeMethod() { this.SomethingHappened.RaiseEvent(this, EventArgs.Empty); } My question: Is this a good idea? Are we missing anything by not having the standard On method? (One thing I notice is that it doesn't work with events that have explicit add/remove code.)

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• JAVA - Download PDF file from Webserver

  - by Augusto Picciani

  I need to download a pdf file from a webserver to my pc and save it locally. I used Httpclient to connect to webserver and get the content body: HttpEntity entity=response.getEntity(); InputStream in=entity.getContent(); String stream = CharStreams.toString(new InputStreamReader(in)); int size=stream.length(); System.out.println("stringa html page LENGTH:"+stream.length()); System.out.println(stream); SaveToFile(stream); Then i save content in a file: //check CRLF (i don't know if i need to to this) String[] fix=stream.split("\r\n"); File file=new File("C:\\Users\\augusto\\Desktop\\progetti web\\test\\test2.pdf"); PrintWriter out = new PrintWriter(new FileWriter(file)); for (int i = 0; i < fix.length; i++) { out.print(fix[i]); out.print("\n"); } out.close(); I also tried to save a String content to file directly: OutputStream out=new FileOutputStream("pathPdfFile"); out.write(stream.getBytes()); out.close(); But the result is always the same: I can open pdf file but i can see white pages only. Does the mistake is around pdf stream and endstream charset encoding? Does pdf content between stream and endStream need to be manipulate in some others way?

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• Problem with circular definition in Scheme

  - by user8472

  I am currently working through SICP using Guile as my primary language for the exercises. I have found a strange behavior while implementing the exercises in chapter 3.5. I have reproduced this behavior using Guile 1.4, Guile 1.8.6 and Guile 1.8.7 on a variety of platforms and am certain it is not specific to my setup. This code works fine (and computes e): (define y (integral (delay dy) 1 0.001)) (define dy (stream-map (lambda (x) x) y)) (stream-ref y 1000) The following code should give an identical result: (define (solve f y0 dt) (define y (integral (delay dy) y0 dt)) (define dy (stream-map f y)) y) (solve (lambda (x) x) 1 0.001) But it yields the error message: standard input:7:14: While evaluating arguments to stream-map in expression (stream-map f y): standard input:7:14: Unbound variable: y ABORT: (unbound-variable) So when embedded in a procedure definition, the (define y ...) does not work, whereas outside the procedure in the global environment at the REPL it works fine. What am I doing wrong here? I can post the auxiliary code (i.e., the definitions of integral, stream-map etc.) if necessary, too. With the exception of the system-dependent code for cons-stream, they are all in the book. My own implementation of cons-stream for Guile is as follows: (define-macro (cons-stream a b) `(cons ,a (delay ,b)))

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• Iphone xcode simulator crashes when I move up and down on a table row

  - by Frames84

  I can't get my head round this. When the page loads, everything works fine - I can drill up and down, however 'stream' (in the position I have highlighted below) becomes not equal to anything when I pull up and down on the tableview. But the error is only sometimes. Normally it returns key/pairs. If know one can understand above how to you test for // (int)[$VAR count]} key/value pairs in a NSMutableDictionary object - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { static NSString *FirstLevelCell = @"FirstLevelCell"; UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:FirstLevelCell]; if(cell == nil) { cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:FirstLevelCell] autorelease]; } NSInteger row = [indexPath row]; //NSDictionary *stream = (NSDictionary *) [dataList objectAtIndex:row]; NSString *level = self.atLevel; if([level isEqualToString:@"level2"]) { NSMutableDictionary *stream = [[NSMutableArray alloc] init]; stream = (NSMutableDictionary *) [dataList objectAtIndex:row]; // stream value is (int)[$VAR count]} key/value pairs if ([stream valueForKey:@"title"] ) { cell.textLabel.text = [stream valueForKey:@"title"]; cell.textLabel.numberOfLines = 2; cell.textLabel.font =[UIFont systemFontOfSize:10]; NSString *detailText = [stream valueForKey:@"created"]; cell.detailTextLabel.numberOfLines = 2; cell.detailTextLabel.font= [UIFont systemFontOfSize:9]; cell.detailTextLabel.text = detailText; NSString *str = @"http://www.mywebsite.co.uk/images/stories/Cimex.jpg"; NSData *imageURL = [[NSData alloc] initWithContentsOfURL:[NSURL URLWithString:str]]; UIImage *newsImage = [[UIImage alloc] initWithData:imageURL]; cell.imageView.image = newsImage; [stream release]; } } else { cell.textLabel.text = [dataList objectAtIndex:row]; } return cell; } Thanks for your time

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• How to Use Steam In-Home Streaming

  - by Chris Hoffman

  Steam’s In-Home Streaming is now available to everyone, allowing you to stream PC games from one PC to another PC on the same local network. Use your gaming PC to power your laptops and home theater system. This feature doesn’t allow you to stream games over the Internet, only the same local network. Even if you tricked Steam, you probably wouldn’t get good streaming performance over the Internet. Why Stream? When you use Steam In-Home streaming, one PC sends its video and audio to another PC. The other PC views the video and audio like it’s watching a movie, sending back mouse, keyboard, and controller input to the other PC. This allows you to have a fast gaming PC power your gaming experience on slower PCs. For example, you could play graphically demanding games on a laptop in another room of your house, even if that laptop has slower integrated graphics. You could connect a slower PC to your television and use your gaming PC without hauling it into a different room in your house. Streaming also enables cross-platform compatibility. You could have a Windows gaming PC and stream games to a Mac or Linux system. This will be Valve’s official solution for compatibility with old Windows-only games on the Linux (Steam OS) Steam Machines arriving later this year. NVIDIA offers their own game streaming solution, but it requires certain NVIDIA graphics hardware and can only stream to an NVIDIA Shield device. How to Get Started In-Home Streaming is simple to use and doesn’t require any complex configuration — or any configuration, really. First, log into the Steam program on a Windows PC. This should ideally be a powerful gaming PC with a powerful CPU and fast graphics hardware. Install the games you want to stream if you haven’t already — you’ll be streaming from your PC, not from Valve’s servers. (Valve will eventually allow you to stream games from Mac OS X, Linux, and Steam OS systems, but that feature isn’t yet available. You can still stream games to these other operating systems.) Next, log into Steam on another computer on the same network with the same Steam username. Both computers have to be on the same subnet of the same local network. You’ll see the games installed on your other PC in the Steam client’s library. Click the Stream button to start streaming a game from your other PC. The game will launch on your host PC, and it will send its audio and video to the PC in front of you. Your input on the client will be sent back to the server. Be sure to update Steam on both computers if you don’t see this feature. Use the Steam > Check for Updates option within Steam and install the latest update. Updating to the latest graphics drivers for your computer’s hardware is always a good idea, too. Improving Performance Here’s what Valve recommends for good streaming performance: Host PC: A quad-core CPU for the computer running the game, minimum. The computer needs enough processor power to run the game, compress the video and audio, and send it over the network with low latency. Streaming Client: A GPU that supports hardware-accelerated H.264 decoding on the client PC. This hardware is included on all recent laptops and PCs. Ifyou have an older PC or netbook, it may not be able to decode the video stream quickly enough. Network Hardware: A wired network connection is ideal. You may have success with wireless N or AC networks with good signals, but this isn’t guaranteed. Game Settings: While streaming a game, visit the game’s setting screen and lower the resolution or turn off VSync to speed things up. In-Home Steaming Settings: On the host PC, click Steam > Settings and select In-Home Streaming to view the In-Home Streaming settings. You can modify your streaming settings to improve performance and reduce latency. Feel free to experiment with the options here and see how they affect performance — they should be self-explanatory. Check Valve’s In-Home Streaming documentation for troubleshooting information. You can also try streaming non-Steam games. Click Games > Add a Non-Steam Game to My Library on your host PC and add a PC game you have installed elsewhere on your system. You can then try streaming it from your client PC. Valve says this “may work but is not officially supported.” Image Credit: Robert Couse-Baker on Flickr, Milestoned on Flickr

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• Streaming desktop with avconv - severe sound issues

  - by Tommy Brunn

  I'm trying to do some live streaming in Ubuntu 12.10, but I'm having some problems with audio. More specifically, the quality is complete garbage and it's at least 10 seconds out of sync with the video. I'm using an excellent guide found here to set up my loopback devices so that I can combine the desktop audio with the microphone input. It seems to work, as I'm able to stream both audio and video to Twitch.tv. But, as I said, the audio quality is terrible. The microphone audio is very, very low, but if I increase it, I get a horrible garbled sound that is absolutely unbearable. Nothing like that is present during VoIP calls or when recording sound alone with the sound recorder, so it's not an issue with the microphone itself. The entire audio stream is also delayed about 10-15 seconds compared to the video stream. I put together an imgur album of my settings. Here is some example output from when I'm streaming: avconv version 0.8.4-6:0.8.4-0ubuntu0.12.10.1, Copyright (c) 2000-2012 the Libav developers built on Nov 6 2012 16:51:11 with gcc 4.7.2 [x11grab @ 0x162fd80] device: :0.0+570,262 -> display: :0.0 x: 570 y: 262 width: 1280 height: 720 [x11grab @ 0x162fd80] shared memory extension found [x11grab @ 0x162fd80] Estimating duration from bitrate, this may be inaccurate Input #0, x11grab, from ':0.0+570,262': Duration: N/A, start: 1353181686.735113, bitrate: 884736 kb/s Stream #0.0: Video: rawvideo, bgra, 1280x720, 884736 kb/s, 30 tbr, 1000k tbn, 30 tbc [alsa @ 0x163fce0] capture with some ALSA plugins, especially dsnoop, may hang. [alsa @ 0x163fce0] Estimating duration from bitrate, this may be inaccurate Input #1, alsa, from 'pulse': Duration: N/A, start: 1353181686.773841, bitrate: N/A Stream #1.0: Audio: pcm_s16le, 48000 Hz, 2 channels, s16, 1536 kb/s Incompatible pixel format 'bgra' for codec 'libx264', auto-selecting format 'yuv420p' [buffer @ 0x1641ec0] w:1280 h:720 pixfmt:bgra [scale @ 0x1642480] w:1280 h:720 fmt:bgra -> w:852 h:480 fmt:yuv420p flags:0x4 [libx264 @ 0x165ae80] VBV maxrate unspecified, assuming CBR [libx264 @ 0x165ae80] using cpu capabilities: MMX2 SSE2Fast SSSE3 FastShuffle SSE4.2 [libx264 @ 0x165ae80] profile Main, level 3.1 [libx264 @ 0x165ae80] 264 - core 123 r2189 35cf912 - H.264/MPEG-4 AVC codec - Copyleft 2003-2012 - http://www.videolan.org/x264.html - options: cabac=1 ref=2 deblock=1:0:0 analyse=0x1:0x111 me=hex subme=6 psy=1 psy_rd=1.00:0.00 mixed_ref=0 me_range=16 chroma_me=1 trellis=1 8x8dct=0 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=4 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=0 b_adapt=1 b_bias=0 direct=1 weightb=0 open_gop=1 weightp=1 keyint=250 keyint_min=25 scenecut=40 intra_refresh=0 rc_lookahead=30 rc=cbr mbtree=1 bitrate=712 ratetol=1.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 vbv_maxrate=712 vbv_bufsize=512 nal_hrd=none ip_ratio=1.25 aq=1:1.00 Output #0, flv, to 'rtmp://live.justin.tv/app/live_23011330_Pt1plSRM0z5WVNJ0QmCHvTPmpUnfC4': Metadata: encoder : Lavf53.21.0 Stream #0.0: Video: libx264, yuv420p, 852x480, q=-1--1, 712 kb/s, 1k tbn, 30 tbc Stream #0.1: Audio: libmp3lame, 44100 Hz, 2 channels, s16, 712 kb/s Stream mapping: Stream #0:0 -> #0:0 (rawvideo -> libx264) Stream #1:0 -> #0:1 (pcm_s16le -> libmp3lame) Press ctrl-c to stop encoding frame= 17 fps= 0 q=0.0 size= 0kB time=10000000000.00 bitrate= 0.0kbitframe= 32 fps= 31 q=0.0 size= 0kB time=10000000000.00 bitrate= 0.0kbitframe= 40 fps= 23 q=29.0 size= 44kB time=0.03 bitrate=13786.2kbits/s dup=frame= 47 fps= 21 q=31.0 size= 93kB time=2.73 bitrate= 277.7kbits/s dup=0frame= 62 fps= 23 q=29.0 size= 160kB time=3.23 bitrate= 406.2kbits/s dup=0frame= 77 fps= 24 q=23.0 size= 209kB time=3.71 bitrate= 462.5kbits/s dup=0frame= 92 fps= 25 q=20.0 size= 267kB time=4.91 bitrate= 445.2kbits/s dup=0frame= 107 fps= 25 q=20.0 size= 318kB time=5.41 bitrate= 482.1kbits/s dup=0frame= 123 fps= 26 q=18.0 size= 368kB time=5.96 bitrate= 505.7kbits/s dup=0frame= 139 fps= 26 q=16.0 size= 419kB time=6.48 bitrate= 529.7kbits/s dup=0frame= 155 fps= 27 q=15.0 size= 473kB time=7.00 bitrate= 553.6kbits/s dup=0frame= 170 fps= 27 q=14.0 size= 525kB time=7.52 bitrate= 571.7kbits/s dup=0 frame= 180 fps= 25 q=-1.0 Lsize= 652kB time=7.97 bitrate= 670.0kbits/s dup=0 drop=32 //Here I stop the streaming video:531kB audio:112kB global headers:0kB muxing overhead 1.345945% [libx264 @ 0x165ae80] frame I:1 Avg QP:30.43 size: 39748 [libx264 @ 0x165ae80] frame P:45 Avg QP:11.37 size: 11110 [libx264 @ 0x165ae80] frame B:134 Avg QP:15.93 size: 27 [libx264 @ 0x165ae80] consecutive B-frames: 0.6% 0.0% 1.7% 97.8% [libx264 @ 0x165ae80] mb I I16..4: 7.3% 0.0% 92.7% [libx264 @ 0x165ae80] mb P I16..4: 0.1% 0.0% 0.1% P16..4: 49.1% 1.2% 2.1% 0.0% 0.0% skip:47.4% [libx264 @ 0x165ae80] mb B I16..4: 0.0% 0.0% 0.0% B16..8: 0.1% 0.0% 0.0% direct: 0.0% skip:99.9% L0:42.5% L1:56.9% BI: 0.6% [libx264 @ 0x165ae80] coded y,uvDC,uvAC intra: 82.3% 87.4% 71.9% inter: 7.1% 8.4% 7.0% [libx264 @ 0x165ae80] i16 v,h,dc,p: 27% 29% 16% 28% [libx264 @ 0x165ae80] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 22% 21% 14% 8% 8% 8% 7% 5% 7% [libx264 @ 0x165ae80] i8c dc,h,v,p: 47% 22% 20% 11% [libx264 @ 0x165ae80] Weighted P-Frames: Y:0.0% UV:0.0% [libx264 @ 0x165ae80] ref P L0: 96.4% 3.6% [libx264 @ 0x165ae80] kb/s:474.19 Received signal 2: terminating. Any ideas on how I can resolve this? The video delay is perfectly acceptable, so I wouldn't think that it's a network issue that's causing the delay in the audio. Any help would be appreciated.

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• BIP and Mapviewer Mash Up I

  - by Tim Dexter

  I was out in Yellowstone last week soaking up various wildlife and a bit too much rain ... good to be back until the 95F heat yesterday. Taking a little break from the Excel templates; the dev folks are planing an Excel patch in the next week or so that will add a mass of new functionality. At the risk of completely mis leading you I'm going to hang back a while. What I have written so far holds true and will continue to do so. This week, I have been mostly eating 'mapviewer' ... answers on a post card please, TV show and character. I had a request to show how BIP can call mapviewer and render a dynamic map in an output. So I hit the books and colleagues for some answers. Mapviewer is Oracle's geographic information system, hereby known as GIS. I use it a lot in our BIEE demos where the interaction with the maps is very impressive. Need a map of California and its congressional districts? I have contacts; Jerry and David with their little black box of maps. Once in my possession I can build highly interactive, clickable maps that allow the user to drill into more information using a very friendly interface driving BIEE content and navigation. But what about maps in BIP output? Bryan Wise, who has written some articles on this blog did some work a while back with the PL/SQL API interface. The extract for the report called a function that in turn called the mapviewer server, passing a set of mapping requirements, it then returned a URL to a cached copy of that map. Easy to then have BIP render that image. Thats still very doable. You need to install a couple of packages and then load the mapviewer java APIs into the database. Then you can write your function to the APIs. A little involved? Maybe, but the database is doing all the heavy lifting for you. I thought I would investigate another method for getting the maps back into BIP. There is a URL interface you can call, this involves building an XML message to be passed to the mapviewer server. It's pretty straightforward to use on the mapviewer side. On the BIP side things are little more tricksy. After some unexpected messing about I finally got the ubiquitous Hello World map to render using the URL method. Not the most exciting map in the world, lots of ocean and a rather long URL to get it to render. http://127.0.0.1:9704/mapviewer/omserver?xml_request=%3Cmap_request%20title=%22Hello%20World%22%20datasource=%22cagis%22%20format=%22GIF_STREAM%22/%3E Notice all of the encoding in the URL string to handle the spaces, quotes, etc. All necessary to get BIP to make the call to the mapviewer server correctly without truncating the URL if it hits a real space rather than a %20. With that in mind constructing the URL was pretty simple. I'm not going to get into the content of the URL too much, for that you need to bone up on the mapviewer XML API. Check out the home page here and the documentation here. To make the template portable I used the standard CURRENT_SERVER_URL parameter from the BIP server and declared that in my template. <?param@begin:CURRENT_SERVER_URL;'myserver'?> Ignore the 'myserver', that was just a dummy value for testing at runtime it will resolve to: 'http://yourserver:port/xmlpserver' Not quite what we need as mapviewer has its own server path, in my case I needed 'mapviewer/omserver?xml_request=' as the fixed path to the mapviewer request URL. A little concatenation and substringing later I came up with <?param@begin:mURL;concat(substring($CURRENT_SERVER_URL,1,22),'mapviewer/omserver?xml_request=')?> Thats the basic URL that I can then build on. To get the Hello World map I need to add the following: <map_request title="Hello World" datasource="cagis" format="GIF_STREAM"/> Those angle brackets were the source of my headache, BIPs XSLT engine was attempting to process them rather than just pass them. Hok Min to the rescue ... again. I owe him lunch when I get out to HQ again! To solve the problem, I needed to escape all the characters and white space and then use native XSL to assign the string to a parameter. <xsl:param xdofo:ctx="begin"name="pXML">%3Cmap_request%20title=%22Hello%20World%22 %20datasource=%22cagis%22%20format=%22GIF_STREAM%22/%3E</xsl:param> I did not need to assign it to a parameter but I felt that if I were going to do anything more serious than Hello World like plotting points of interest on the map. I would need to dynamically build the URL, so using a set of parameters or variables that I then concatenated would be easier. Now I had the initial server string and the request all I then did was combine the two using a concat: concat($mURL,$pXML) Embedding that into an image tag: <fo:external-graphic src="url({concat($mURL,$pXML)})"/> and I was done. Notice the curly braces to get the concat evaluated prior to the image call. As you will see next time, building the XML message to go onto the URL can get quite complex but I have used it with some data. Ultimately, it would be easier to build an extension to BIP to handle the data to be plotted, it would then build the XML message, call mapviewer and return a URL to the map image for BIP to render. More on that next time ...

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• mod_rewrite apache

  - by Peter

  is there any way to hide redirected url, here is what I think: RewriteEngine On RewriteCond %{REQUEST_FILENAME} -f RewriteRule ^(.*)$ http://minteddomain.com/mint/pepper/tillkruess/downloads/tracker.php?url=http://%{HTTP_HOST}%{REQUEST_URI}&force So the long redirected url http://minteddomain.com/mint/pepper/tillkruess/downloads/tracker.php?url=http://%{HTTP_HOST}%{REQUEST_URI} to something shorter like /mintedomain.com/track/ It is possible? Adrian edit: Andrew: This is a stats software Mint (haveamint.com) with File Download tracker plugin. The File Download tracker works in this way: in .htaccess every file (zip, rar, txt,...) is redirected to the tracker.php file (because the stats): http://mydomain.com/mint/pepper/tillkruess/downloads/tracker.php?url=http://%{HTTP_HOST}%{REQUEST_URI} So the redirected url look like this for a zip file: http://minteddomain.com/mint/pepper/tillkruess/downloads/tracker.php?url=http://mydomain/downloads/apple.zip This redirected URL is very long and ugly. The best for me would be to redirect this redirected URL to something shorter URL: example: http://mydomain.com/track/downloads/apple.zip.. So the http://mydomain.com/track would be the http://minteddomain.com/mint/pepper/tillkruess/downloads/tracker.php

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• Using the Antenna and J2ME Polish preprocessors interchangeably and setting a variable value

  - by walter

  I have J2ME code, which I want to be able to compile using the J2ME Polish preprocessor or the wtkpreprocessor (antenna). They mostly use the same directives so it usually works, but ... When I want to insert an URL value in the Java code this gives a problem. In Antenna the code would look like this: //#ifdef my.url //# System.out.println("My Url"); //#expand String location = "%my.url%"; //#else System.out.println("Default"); String location = "http://www.some.default.url.com"; //#endif and in J2ME Polish it would look like this: //#ifdef my.url:defined //# System.out.println("My Url"); //#= String location = "${my.url}"; //#else System.out.println("Default"); String location = "http://www.some.default.url.com"; //#endif I want some way in which I can use the preprocessors interchangeably and still be able to set the url in the build.xml, any ideas?

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• Groovy Grails, How do you stream or buffer a large file in a Controller's response?

  - by Julian Noye

  Hi Guys I have a controller that makes a connection to a url to retrieve a csv file. I am able to send the file in the response using the following code, this works fine. def fileURL = "www.mysite.com/input.csv" def thisUrl = new URL(fileURL); def connection = thisUrl.openConnection(); def output = connection.content.text; response.setHeader "Content-disposition", "attachment; filename=${'output.csv'}" response.contentType = 'text/csv' response.outputStream << output response.outputStream.flush() However I don't think this method is inappropriate for a large file, as the whole file is loaded into the controllers memory. I want to be able to read the file chunk by chunk and write the file to the response chunk by chunk. Any ideas?

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• Conecting bash script with a txt file

  - by cathy

  I have a txt file with 100+ lines called page1.txt; odd lines are urls and even lines are url names. I have a bash file already created that checks urls for completion. Except right now, the process is really manual because I have to modify the bash every time I need to check a url. So I need to connect the bash to the txt using the variable url. $url should get all the odd lines from page1.txt and check if the link is complete or not. Also, how would I write a variable called name that derives from the url the 7 digits? bash file manually: url=http://www.-------------/-/8200233/1/ name=8200233 lynx -dump $url > $name.txt I would prefer if the bash file could add "Complete/In-Complete " at the beginning of every even line in the page1.txt file but a new text file could be also created to keep track of the Completes/In-completes.

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• How to clear a Firefox address bar without selecting its content?

  - by zuba

  Sometimes I need to move an url from an app to a browser. I select the url, say in gvim, and make Firefox window active. Then I see that I should clear address bar before pasting the new url, which requires selecting existing url, which wipes the new url from PRIMARY clipboard out. What is the best way to put the new url from PRIMARY clipboard to address bar? Is there a shortcut to clear address bar and then to move focus there? ps I know I can use Ctrl-C to put the new url to CLIPBOARD clipboard, but I prefer to use PRIMARY clipboard.

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• Problem doing SVN Vendor Branch - merge

  - by Gyan

  Hi, I am trying to use the svn vendor branch to upgrade the third party library. (We have modified the source code) I followed all the steps to create the vendor branch:: created the vendor branch for old version (3rd party library) created the vendor branch for latest version (3rd party library) copied the latest version to current folder using (usign svn_load_dirs.pl script) structure of vendor repository in svn URL/vendor/library/3.5.0 URL/vendor/library/3.7.0 URL/vendor/library/current I have the library-3.5.0 used/modified at URL/trunk/library/customized-library I have a problem when I try to merge the difference between URL/vendor/library/3.7.0 and URL/vendor/library/3.5.0 to URL/trunk/library/customized-library I am at the folder where URL/trunk/library/customized-library is checked out and I use following command to do the merge svn merge URL/vendor/library/3.5.0 URL/vendor/library/current . --accept PARAMETERS when I use theirs-conflict for accept parameter, It ignores all of my changes to the old version and copies files from 3.7.0 when I user mine-conflict, it ignores the files in 3.7.0 when I use postpone, it throws exception "tree conflict" Thanks Gyan

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• C# Image Download

  - by Nouman Zakir

  A C# class that makes it easier to download images from the web. Use the following code in your program to download image files such as JPG, GIF, PNG, etc from the internet using WebClient class. using System;using System.Drawing;using System.Drawing.Imaging;using System.IO;using System.Net;public class DownloadImage { private string imageUrl; private Bitmap bitmap; public DownloadImage(string imageUrl) { this.imageUrl = imageUrl; } public void Download() { try { WebClient client = new WebClient(); Stream stream = client.OpenRead(imageUrl); bitmap = new Bitmap(stream); stream.Flush(); stream.Close(); } catch (Exception e) { Console.WriteLine(e.Message); } } public Bitmap GetImage() { return bitmap; } public void SaveImage(string filename, ImageFormat format) { if (bitmap != null) { bitmap.Save(filename, format); } }}

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