I have looked all over (spent about 7 hours). I have found numerous articles on how to map a drive (google drive, onedrive etc). What I cannot seem to find an answer to is this: Once I have mapped the drive can I use the files on that drive just like I use files on a server. Open the file, read a record, write a record. I have created a file, mapped a network drive, wrote records to the file and retrieved records from the file. I have a home grown database that is implemented with a large binary (as opposed to text) file. I have to go to a byte position and read a fixed number of bytes. If WebDAV is copying the file to my computer and then writing it back this would make my file access way to slow and I cannot seem to find an answer. Some programmers I have talked to say I cannot even do that, yet I can. Any direction would be very much appreciated.
Charlie
That's likely because standard WebDAV doesn't allow updating ranges of resources only, so the whole thing needs to be written back.
Related
I'm making an application which plays music from a remote server, and I would like to be able to sort by author/album/year/etc. AFAIK the only way to do this is by reading the metadata but I don't want to have to download the whole audio file just to read the metadata, is there any way to separate them and download only the metadata?
BTW. I am using webdav_client for flutter, which uses dio as a back-end so instructions for that specifically would be greatly appreciated. TY
Firstly, you can usually make a request for a certain byte range by using ranged requests. This is dependent on server behavior. Most servers support it, but many don't.
Next, you need to figure out the location of the ID3 tags you want. Some versions of ID3 are located at the front of the file. Some are at the back. Therefore, you should probably request the first 128 KB or so of the file and search for ID3 data, while also getting the Length response header. Then if you don't find your tag at the beginning, you can make a request for the last 128 KB or whatever of the file, and search there.
Most MP3 files aren't very big, and bandwidth is usually plentiful. Depending on the size and scope of this project, you might actually find it more efficient to just download the whole files.
I don't think that it is possible to read just the ID3-metadata (at the beginning or the end) of the audiofile without downloading the entire file first.
One idea would be to extract this information on the server side and provide it separately, in addition to the audio file itself. To do this, you would need one of the well-known extraction tools available for your platform. However, if you need to download hundreds or thousands of companion files, I am not sure about the reliability of such a system.
What's the best practise for storing a large (expanding) number of small files on a server, without running into inode limitations?
For a project, I am storing a large number of small files on a server with 2TB HD space, but my limitation is the 2560000 allowed inodes. Recently the server used up all the inodes and was unable to write new files. I subsequently moved some files into databases, but others (images and json files remain on the drive). I am currently at 58% inode usage, so a solution is required imminently.
The reason for storing the files individually is to limit the number of database calls. Basically the scripts will check if the file exists and if so, then return results dependently. Performance wise this makes sense for my application, but as stated above it has limitations.
As I understand it does not help to move the files into sub-directories, because each inode points to a file (or a directory file), so in fact I would just use up more inodes.
Alternatively I might be able to bundle the files together in an archive type of file, but that will require some sort of indexing.
Perhaps I am going about this all wrong, so any feedback is greatly appreciated.
On the advice of arkascha I looked into loop devices and found some documentation about losetup. Remains to be tested.
i'm asp.net beginner and currently working in "upload download file" project with asp.net and vb.net as code behind language (like skydrive's web).
what i'm want ask is about upload file in server, must we store path file, size, accessed or created date into database? as we know we can use directory listing in system.io.
Thanks for your help.
You definetly want to store the path of the file. You want a way to find the file ;) Maybe later you will have multiple servers, replication or other fancy things.
For the rest, it depends a bit on the type of website. If it's going to get high traffic then store it in the database, this will limit the number of IO call (very slow). Also, it'll be a lot easier to handle sorting and queries. (sort by date, pull only the read onyl files, ...).
Database will also help if you want to show history or statistique.
You can save file in some directory and can save path of that file in database. You can also store size and created date of that file in DB. But storing a file in DB is a bit difficult. Rather than save file in Directory and save path of that file in DB
you could store the file information in a database to built some extra features like "avoid storing duplicate files", because you are having a faster search in the database! if you search the filesystem always a recursive function call get started
I am currently working on a project where i need to store few files and folders in encrypted manner. This project will be platform independent and hence will be written in Java.
Instead of encrypting individual file and folder, we have been thinking of using some virtual file-system where a single container file will hold complete file-system.
Most of the open source virtual encrypted file-system tools we studied work on following principle.
mount the virtual file system (using secure password)
use this filesystem
finally dismount it
But the main problem here we face is that anyone who has access of the PC (e.g. network admin) will be able to see decrypted files when virtual drive is mounted. We want to restrict access to encrypted file system at process level. No one else in same OS session should be able to see the contents, hence no drive mounting, etc.
So we are looking for some open source tool which will provided some some APIs using which we will be able to access files in encrypted container without mounting it.
can anyone point us to any such library?
This thing I'd normally say was pretty cool.
http://www.pismotechnic.com/pfm/
But I've recently accidently copied a sub-repository in a mercurial repository to another folder and when that happened a lot of files got magically messed up. If you don't mind possible issues like that (eg. keeping backups) this could be a solution for you.
I've stumbled upon this question while hunting for an alternative because corrupted files are definitely not on my requirement list.
I have a .jpg file which represents the current image from a webcam. User's will be downloading this file at an interval of once a second. Because there could be dozens of users reading it, this could be dozens of times a second (which is normal for any web server).
Problem is, this image is updated by a 3rd party application also once a second which "spiders" my local networks webcam portal image. This is so we can build our webcams into our current administration panel.
The problem I am already finding is ASP.net sometimes gets an error it can not access the file because it is open for write permissions by the bot. Likewise, the bot can not access it because IIS is feeding it to the user.
The bot uses io.streamwriter to save the data to the file, and my script uses Response.WriteFile to send the file to the script. (I need to use an actual ASP.net page with a JPG content-type that feeds the file to make sure only users with a active session can view the JPG).
My question is what is the best practices for this? I know why it's happening but what is the best resolution for this? Would storing as a BLOB in a database maybe be smarter since databases are created for concurrent read/writing already? Is there an easier way of doing this with a file I have not thought of yet?
Thanks in advance,
Anthony Greco
Using a BLOB will work if the readers use SNAPSHOT isolation model (SQL Server 2005 and up). See Download and Upload images from SQL Server via ASP.Net MVC for how to stream an image from a BLOB, and see Understanding Row Versioning-Based Isolation Levels for a lecture on SNAPSHOT.
But using a BLOB may be overkill, you could get away with something much simpler. For instance, if you only have one ASP.Net process, then you could have a global volatile variable for the current file name. The writer writes the JPG into a new file, and then updates the global 'current' file name with an Interlocked.CompareExchange operation (it has to be Compare because a newer writer might actually finish faster, outrun a previous writer, and you want to preserve the latest update). There are still some issues left to solve (find out the file name at startup, clean up old files etc) but they are all fairly ease to solve.
If you have a farm of servers, or multiple ASP.Net processes serving the site, then things could get complicated. I would still do a rotating file name and do a try-and-error approach (try to respond with newest file, fall back to previous older one if conflict is detected).
You could get the bot to write the data to a different filename and then do a delete and rename to the filename being served by ASP.Net. This should reduce the file lock time down to the time for a delete and rename to occur. To clarify:
ASP.Net serving image from "webcam.jpg"
bot writes image data to "temp.jpg"
when last image byte written, bot deletes "webcam.jpg" and renames "temp.jpg" to "webcam.jpg"
ASP.Net should check "webcam.jpg" exists, if not wait 10ms (or suitable small increment) and check again.