it is possible to use DotNetZip to create a zip from an accessed file (eg log file from another application) ?
so create a zip when the log file gets written through the other application
Hmm, well, yes, if you are willing to write some code.
One way to do it is to compress the file AFTER it has been written and closed.
You would need to have an app that runs with a filesystem watcher, and when it sees the log file being closed, it compresses that log file into a zip.
If you mean to imply, a distinct app that writes to a file and it automagically writes into a zip file, no I don't know of a simple way to do that. There is one possibility: if the 3rd party app accepts a System.IO.Stream in which to write the log entries. In that case, you can do that with DotNetZip. You can get a writeable stream from DotNetZip, into which the app writes content. It is compressed as it is written, and when the writing is complete, DotNetZip closes the zipfile. To use this, check the ZipFile.AddEntry() method that accepts a WriteDelegate. It's in the documentation.
Related
I am using Azure data Lake Store for files Storage. I am using operations like
Creating a main file
Creating part files
Appending these part files to main file (for Concurrent append)
Example:
There is main log file (eventually will contain logs from all
programs)
There are part log file that each program creates solely and then
append to the main log file
The workflow runs really file but i have noticed some unknown file getting uploaded onto the store directory. These files name is a GUID an has no extension, moreover these unknown files are empty.
Does anyone knows what might be the reason for these extra files.
Thanks for reformatting your question. This looks like some processing artefacts that probably will disappear shortly after. How did you upload/create your files?
I am working on vb.net application where I wanted to create and read a file. File will have specific extension for ex. .abcb the way I want my application to work is:
can create a file with .abcd extension
should read .abcd files only(and also application created files only so altered extension shouldn't be working)
.abcd files should show some garbage data when open in any other application(ex. word, notepad any image viewer etc.)
Now my application does 1,2(partly) step, i.e. it creates a file and load data also, it reads .abcd files only(not the altered files)
but created file can be read by other software's also.I tried searching a lot but have not found anything and don't know where to start.
Any help is appreciated!
if you don't want other programs to be able to read the content of your file then your going to have to mask it in some way, which is usually done with encryption.
assuming your not too worried about the key being compromised, the easiest way to accomplish this would be to generate a key with something like System.Security.Cryptography and use that key to encyrpt everything you send to the file and everything you read from it.
as for making your own file extension, you can make the extension of a file whatever you want when you make it:
Dim fs As FileStream = File.Create("/path/to/file/filename" & ".abcd")
the only thing that the extension does is tell the OS what progam to use when opening a file by default, which will probably be notepad since your making your own extension
I have a text file. Now I have changed its file type from .txt to .abc. My VB.NET program loads the text into textboxes from that file. After changing the file type, however, other apps like NotePad and Word are able to open and read my .abc file.
Is there any way that only my application will be able to open/read from the file and no other app would be able to do so? What I mean is, suppose I have a PhotoShop document .psd file, no other app, rather that photoshop itself, can open it. How do I make my file unreadable by other apps?
There is no way to prevent an app that you don't develop from opening any file. The extensions are just there for helping us humans, and maybe a bit for the computer to know the default app you select for an extension.
Like you said, a .txt file can be opened by many many apps. You can open a .txt file with Notepad, Firefox, VSCode, and many others.
Same way, a .psd file can be opened by many many apps. You can open that .psd file with Photoshop, but also Notepad, Firefox, and VSCode, and probably the same apps as above.
The difference is which apps can read and understand the file.
In order to make a file not understandable by other apps, you need to make it into a format that cannot recognize, because you planned it "in secret".
Like Visual Vincent said above, you could encrypt the file in a way, or you can have a binary file, that basically only your app knows know to understand.
Since you dont own the app you want the file to be understood by, then you either have to accept that it can be opened by any app that can open files, or you can try to encrypt the file outside the app, or like zipping it with a password, and then decrypting or unzipping when you want to use it.
Firstly, any file can be read unless it is still open by a particular process or service. Even PhotoShop files can be 'read' by NotePad - try it!
So, an attempt at my first answer...
You can try a couple of methods to prevent opening the file, for instance, applying a file lock. As an example, SQL Server .mdf files are locked by the SQL Server service. This happens because the files are maintained in an open state, however; your application would have to remain running to keep these files open. Technically, though, the files can still be copied.
Another way is to set the hidden attribute for the file. This hides the file from the less savvy users, but it will be displayed if the user show's hidden files.
And my second answer: You refer to the format of files by saying only PhotoShop can read or write its own files (not true, but I know what you're saying).
The format of the file must be decided by yourself. You must determine how you are going to store the data that you output from your application. It looks like you have been attempting to write your application data into a text file. Perhaps you should try writing to binary files instead. Binary files, while not encrypted, as suggested by Visual Vincent in the comments to your question, still provide a more tailored approach to storing your data.
Binary files write raw binary data instead of humanised text. For instance, if you write an integer to the file it will appear as a string of four bytes, not your usual 123456789 textual format.
So, you really need to clarify what data you want to write to the file, decide on a set structure to your file (as you also have to be able to read it back in to your application) and then be able to write the information.
The sequence of events that I'm trying to make happen in Meteor is:
On the client browser, upload a zip file and send it to the server
On the server, receive the zip file and hold it in a memory object
Unzip the memory object into individual objects representing the contents
Process the individual files one at a time
Return success/failure status to the client
I have steps 1 and 2 working, using EJSON to stringify the contents of the zip file on the client and again to convert it back to its original form on the server. The problem I'm encountering is when I try to unzip the object on the server. It seems that every unzip library available wants to operate directly on a file or stream, not on a memory object.
I suppose I could write the object to disk and read it back again, but that seems like an unnecessary step. Is there a library available to unzip a memory object? Alternatively, is there a way to create a stream directly from the object that I can then feed to the unzip routine?
Any advice would be greatly appreciated.
You could use the unzip module from npm. It accepts streaming input and allows you to process output without saving to disk.
It will take some work to wrap it to work with meteor. Your two options are the meteorhacks:npm package or upgrading to the Meteor 1.3 beta.
I have a program which takes input from S3, generates a text file, and then sends it to the mapper class. I am unable to write the file to S3, from where the mapper can read it later. Now, I realize that we cannot write files to S3 directly, so I am trying to upload the text file created to S3 using copyFromLocalFile(). However, I get a null pointer exception in the following line:
fs.copyFromLocalFile(true, new Path(tgiPath), mapIP);
I am creating the text file in main function, so I am not sure where exactly it's being created. The only reason behind the null pointer exception, that I can think of is that the text file is not being written on the local disk. So my question is: How do I write files on the local disk? If I just specify the name of the file while creating it, where is it created and how do I access it?
Have a look at Jets3t
This seems to be exactly what you need.
Jets3t is awesome, but I am using Google's App Engine, and it doesn't work on there because of threading limitations.
I banged my head against the wall until I came up with a solution that worked on App Engine by combining a bunch of existing libraries: http://socialappdev.com/using-amazon-s3-with-google-app-engine-02-2011