Here is my case:
I'm using ABCPDF to generate a HTML document from a .DOCX file that I need to show on the web.
When you export to HTML from ABCPDF you generate a HTML and a folder with support files (.css, .js, .png)
Now these HTML files may contain quite sensitive data so I immediately after generating the files, I move them to a password-protected .zip file (from which I fetch them later)
The problem is, that this leaves the files unencrypted on the HDD for a few seconds and even longer if I'm (for some reason) unable to delete them at once.
I'd like suggestions for another way of doing this. I've looked in to a ram drive, but I'm not happy with installing such drivers on my servers. (AND the RAM drive would still be accessible from the OS)
The cause of the problem here might be that ABCPDF can only export HTML as files (since its multiple files) and not as a stream.
Any ideas?
I'm using .NET 4.6.x and c#
Since all your files except the .HTML are anonymous, you can use the suggested way of writing the HTML to a stream. Only all other files will be stored to the file system.
http://www.websupergoo.com/helppdfnet/source/5-abcpdf/doc/1-methods/save.htm
When saving to a Stream the format can be indicated using a Doc.SaveOptions.FileExtension property such as ".htm" or ".xps". For HTML you must provide a sensible value for the Doc.SaveOptions.Folder property.
http://www.websupergoo.com/helppdfnet/source/5-abcpdf/xsaveoptions/2-properties/folder.htm
This property specifies the folder where to store additional data such as images and fonts. it is only used when exporting documents to HTML. It is ignored otherwise.
For a start, try using a simple MemoryStream to hold the sensitive data. If you get large files or high traffic, open an encrypted stream to a file on your system.
Related
We are working with PDF files and want to check them if they are signed or not.
Currently we are using SecureBlackbox and it is working fine for small files.
Problem is with large (more than 2GB) files. When loading it gets out of memory or similar error.
Is there any way or library (for .net) to open large files and getting signature info from PDF?
What I tried so far with no success: ITextSharp, PdfSharp, SecureBlackbox
Ideal way would be not loading whole content of file, just information what is needed, so not to use so much memory or space.
Thank you for your suggestions.
Have a nice day.
Fitik
Suppose, I have a list of MP3 files on my server. And I want a user to download multiple files (which he wants through any means). For, this what i want is to create the zip file dynamically and while saving it into the Output Stream using the dotnetzip or ioniczip libraries.
Well, that's not the perfect solution if the zip file got heavy in size. As, in that scenario the server doesn't support resumable downloads. So, to overcome this approach, I need to handle the zip file structure internally and provide the resume support.
So, is there any library (open source) which i can use to provide resumable dyanamic zip files stream directly to the Output Stream. Or, if possible I will be happy if someone let me know the structure of zip file specially the header content + data content.
Once a download has started, you should not alter the ZIP file anymore. Because then a resume will just result in a broken ZIP file. So make sure your dynamically created ZIP file stays available!
The issue of providing resume-functionality was solved in this article for .NET 1.1, and it is still valid and functional.
I have got stuck in a problem while downloading documents from database.
Currently I'm working in ASP.net project and this is my first career project.
We have some documents which we store in database. The documents(.pdf,.doc,.png,.docx,xls,xlsx) are stored in binary format with their type specified.
I can download one document using Response.write. But now i have to concatenate some documents and then allow user to download on button click.
I have googled a lot. Developers have said that this is impossible. But still i feel that this can be done.
However if this is impossible i thought that i will save these individual documents first at some server location and then zip them and then allow user to download. But how would i be able to save the individual document in their original format at server location.
Please help me out. I'm in big problem.
It is not impossible to read more than one document from a database and zip them up before presenting the zip file to the response stream. You can do this all in process, there is no need to save the documents to the server.
This code uses Ionic.Zip to zip up several files and write them to a MemoryStream:
foreach (var file in files)
{
zipFile.AddEntry(file.FileName, file.ContentBytes); // these are the file bytes
}
var zipMs = new MemoryStream();
zipFile.Save(zipMs);
zipMs.Seek(0, SeekOrigin.Begin);
zipMs.Flush();
The file.FileName includes the extensions (.docx) of the documents and when downloading through the browser, everything is displayed and saved correctly.
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've got a project which requires a fairly complicated process and I want to make sure I know the best way to do this. I'm using ASP.net C# with Adobe Flex 3. The app server is Mosso (cloud server) and the file storage server is Amazon S3. The existing site can be viewed at NoiseTrade.com
I need to do this:
Allow users to upload MP3 files to
an album "widget"
After the user has uploaded their
album/widget, I need to
automatically zip the mp3 (for other
users to download) and upload the
zip along with the mp3 tracks to
Amazon S3
I actually have this working already (using client side processing in Flex) but this no longer works because of Adobe's flash 10 "security" update. So now I need to implement this server-side.
The way I am thinking of doing this is:
Store the mp3 in a temporary folder
on the app server
When the artist "publishes" create a
zip of the files in that folder
using a c# library
Start the amazon S3 upload process (zip and mp3s)
and email the user when it is
finished (as well as deleting the
temporary folder)
The major problem I see with this approach is that if a user deletes or adds a track later on I'll have to update the zip file but the temporary files will not longer exist.
I'm at a loss at the best way to do this and would appreciate any advice you might have.
Thanks!
The bit about updating the zip but not having the temporary files if the user adds or removes a track leads me to suspect that you want to build zips containing multiple tracks, possibly complete albums. If this is incorrect and you're just putting a single mp3 into each zip, then StingyJack is right and you'll probably end up making the file (slightly) larger rather than smaller by zipping it.
If my interpretation is correct, then you're in luck. Command-line zip tools frequently have flags which can be used to add files to or delete files from an existing zip archive. You have not stated which library or other method you're using to do the zipping, but I expect that it probably has this capability as well.
MP3's are compressed. Why bother zipping them?
I would say it is not necessary to zip a compressed file format, you are only gong to get a five percent reduction in filesize, give or take a little. Mp3's dont really zip up by their nature the have compressed most of the possible data already.
DotNetZip can zip up files from C#/ASP.NET. I concur with the prior posters regarding compressibility of MP3s. DotNetZip will automatically skip compression on MP3, and just store the file, just for this reason. It still may be interesting to use a zip as a packaging/archive container, aside from the compression.
If you change the zip file later (user adds a track), you could grab the .zip file from S3, and just update it. DotNetZip can update zip files, too. But in this case you would have to pay for the transfer cost into and out of S3.
DotNetZip can do all of this with in-memory handling of the zips - though that may not be feasible for large archives with lots of MP3s and lots of concurrent users.