I'm not used to work with remote resources, so maybe this question is trivial, but I'm not sure how to implement it.
I need to load a collection of images that are placed in a http folder, for example http://www.myexsamplesite.com/images.
Inside this directory I could have N images with different names.
I need to show these images in a WinForms application (in a ListView).
The alternative that I'm studying is downloading the images to a tmp dir, and then load them from disk from my WinForms application. I'm using the following:
WebClient fileReader = new WebClient();
fileReader.DownloadFile(imageAddress, filePath);
to download the files to disk. My question is:
How can I download all the files in the http folder? I guess that I need to enumerate the files in the folder and then download one to one.
The second question and most important. I'm sure that there is a much better mechanism to perform this task. So:
Is there any other way to get the http image content into a System.Drawing.Image?
Remember that I need to get all the files in the http folder.
Thanks in advance
First, to get all of the files, you need a way to enumerate them. HTTP does not have any method that lets you download a whole directory, or technically even list what's in a directory. Some web servers are set to send you a pre-defined web page which displays the list of files in a directory when it lacks a default page, but not all are. You could parse that content to get a list of the files you need to download. Otherwise, you'll need to find a way to get that info programmatically, based on the web application itself.
Second, you can load an image from a stream, as I recall. Instead of using WebClient, you can use HttpWebRequest so that you can access the content stream, and feed that into your constructor. However, I think it may be better/easier for you to use a temp directory and load the files from there. Sometimes unexpected things might happen when loading things from a network stream like this (for example, the stream of GIF images with animations is attempted to be kept open to continually read the frames of the animation), which could cause exceptions at odd times you might not be prepared to debug and understand off the bat.
Finally, note that you would only be using mime type here to verify that your content is an image - so you explicitly would not load something that is mime type application/octet-stream into an image object - but only things like image/jpeg, image/gif, image/png etc.
Related
Recently I was approached to develop an application (asp.net/c#) to allow users to listen some audio files stored in some shared folders.
The users didn't have access to the shared folders, and the files should be streamed. Also, the page should provide the play/stop/pause/forward/back functions, as well as time elapsed/total time information.
So I setup a webservice that access the required file, and return a Byte[] containing the mp3/wav audio (actually I have to convert them to the desired mp3/wav format prior to returning the Byte[]).
The problem is that I have no idea on how to present it in the webpage.
What i need is a webpage with some control that provides the necessary functionalities and information, loaded from a Byte[].
I've researched the web and tried a lot of snippets and controls with no luck at all.
Any ideas or directions on how to implement it?
Thanks in Advance,
António
You could use HTML5's audio tag, if you expect your users to be using fairly recent browser versions. You'd set the src to a URL that would be set up to write your byte[] to the response stream (e.g. maybe store the byte[] in Session, make an .ashx handler page to return that, and set src="myHandler.ashx").
A good approach would be to use silverlight or flash player, even a java applet.
I am using ASP.NET 4.0 + IIS 7 to serve up a number of large PDFs via Response.TransmitFile.
The PDFs are all linearized, i.e. "Fast Web View". However the browser still requires the entire PDF to be downloaded before displaying any of it. All I want to do is show the first page (at least) without having to wait several minutes for the entire PDF to download.
From what I have read, the response header should include ["Accept-Ranges", "bytes"] but this does not seem to help.
Can anyone give me some pointers?
Thanks in advance!
I don't think you can do that easily. For byte range to work you would need many requests to serve the same file. How would you associate all these requests with a single file instance? You would probaly need to save the file to disk or somehonw maintain the file in memory... it could get tricky...
Much simpler would be to save PDFs in a shared folder (a first in first out cache) and let the HTTP 1.1 do the rest.
I have an application in c#.net in which I have embeded the SWF file in SWFObject from COM Object.
Now after installation, the original SWF file also available in the application root directory. So from that place(application root directory) anyone can access that file. But I want to restrict that file from being opened.
axShockwaveFlash1.Movie = Directory.GetCurrentDirectory() + "\\XYZ.swf";
I did something like this.
So how can I restrict that file in application root directory such that only from my application I can access it..??
You can embed the file into a dll or exe file and play it from there. this way it is not (as a seperate file) in the file system at all.
For details see How to embed and access resources by using Visual C#.
You could save the swf file binary data as static bytes in your code and statically load them and convert back to an swf file. The conversion might take a little while but it only occurs once as you open the program.
Edit:
But k3b's answer is better.
Permissions are based on users, not applications, so the short answer is you can't. However, you can build your own application-specific authentication pretty easily. Have your SWF require specific FlashVars to be set in order to move beyond frame 1. People can still decompile your SWF but this will at least stop most people. Another option is to try to store the data within you binary somehow and load the SWF using a byte-array, see this post for one attempt at that.
I am writing an application that would download and replace a pdf file only if the timestamp is newer than that of the already existing one ...
I know its possible to read the time stamp of a file on a local computer via the code line below,
MessageBox.Show(File.GetCreationTime("C:\\test.pdf").ToString());
is it possible to read the timestamp of a file that is online without downloading it .. ?
Unless the directory containing the file on the site is configured to show raw file listings there's no way to get a timestamp for a file via HTTP. Even with raw listings you'd need to parse the HTML yourself to get at the timestamp.
If you had FTP access to the files then you could do this. If just using the basic FTP capabilities built into the .NET Framework you'd still need to parse the directory listing to get at the date. However there are third party FTP libraries that fill in the gaps such as editFTPnet where you get a FTPFile class.
Updated:
Per comment:
If I were to set up a simple html file with the dates and filenames
written manually , I could simply read that to find out which files
have actually been updated and download just the required files . is
that a feasible solution ..
That would be one approach, or if you have scripting available (ASP.NET, ASP, PHP, Perl, etc) then you could automate this and have the script get the timestamp of the files(s) and render them for you. Or you could write a very simple web service that returns a JSON or XML blob containing the timestamps for the files which would be less hassle to parse than some HTML.
It's only possible if the web server explicitly serves that data to you. The creation date for a file is part of the file system. However, when you're downloading something over HTTP it's not part of a file system at that point.
HTTP doesn't have a concept of "files" in the way people generally think. Instead, what would otherwise be a "file" is transferred as response data with a response header that gives information about the data. The header can specify the type of the data (such as a PDF "file") and even specify a default name to use if the client decides to save the data as a file on the client's local file system.
However, even when saving that, it's a new file on the client's local file system. It has no knowledge of the original file which produced the data that was served by the web server.
I am building an interface whose primary function would be to act as a file renaming tool (the underlying task here is to manually classify each file within a folder according to rules that describe their content). So far, I have implemented a customized file explorer and a preview window for the files.
I now have to find a way to inform a user if a file has already been renamed (this will show up in the file explorer's listView). The program should be able to read as well as modify that state as the files are renamed. I simply do not know what method is optimal to save this kind of information, as I am not fully used to C#'s potential yet. My initial solution involved text files, but again, I do not know if there should be only one text file for all files and folders or simply a text file per folder indicating the state of its contained items.
A colleague suggested that I use an Excel spreadsheet and then simply import the row or columns corresponding to my query. I tried to find more direct data structures, but again I would feel a lot more comfortable with some outside opinion.
So, what do you think would be the best way to store this kind of data?
PS: There are many thousands of files, all of them TIFF images, located on a remote server to which I have complete access.
I'm not sure what you're asking for, but if you simply want to keep some file's information such as name, date, size etc. you could use the FileInfo class. It is marked as serializable, so that you could easily write an array of them in an xml file by invoking the serialize method of an XmlSerializer.
I am not sure I understand you question. But what I gather you want to basically store the meta-data regarding each file. If this is the case I could make two suggestions.
Store the meta-data in a simple XML file. One XML file per folder if you have multiple folders, the XML file could be a hidden file. Then your custom application can load the file if it exists when you navigate to the folder and present the data to the user.
If you are using NTFS and you know this will always be the case, you can store the meta-data for the file in a file stream. This is not a .NET stream, but a extra stream of data that can be store and moved around with each file without impacting the actual files content. The nice thin about this is that no matter where you move the file, the meta-data will move with the file, as long as it is still on NTFS
Here is more info on the file streams
http://msdn.microsoft.com/en-us/library/aa364404(VS.85).aspx
You could create an object oriented structure and then serialize the root object to a binary file or to an XML file. You could represent just about any structure this way, so you wouldn't have to struggle with the
I do not know if there should be only one text file for all files and folders or simply a text file per folder indicating the state of its contained items.
design issues. You would just have one file containing all of the metadata that you need to store. If you want speedier opening/saving and smaller size, go with binary, and if you want something that other people could open and view and potentially write their own software against, you can use XML.
There's lots of variations on how to do this, but to get you started here is one article from a quick Google:
http://www.codeproject.com/KB/cs/objserial.aspx