i am working on a system that has 2 parts. the parts are as follow:
1- a producer application that generate and append files in space A, and i cannot modify it ( i must not make noise for this part).
2- a transformer application that copies the files from space A(near the part1) to Space B.
. If part 2 starts to copy a file from A to B and during the copying of the file, part1 wants to append the same file, the part1 will stopped, because the file is under control of part2.
I want to if the part1 wants to append the file, control of the file granted to part 1, and it's not important to what happens for part2.
IS it possible to do that in windows??
If you are working within one computer system (not via network), then in general the correct way would be to monitor the writes, made by part 1, as they happen, and copy the written data on-the-fly. This is achieved using a file system filter driver, which intercepts write operations and captures the data being written.
Related
I need to move several hundred files from a Windows source folder to a destination folder together in one operation. The files are named sequentially (e.g. part-0001.csv, part-002.csv). It is not known what the final file in the sequence will be called. The files will arrive in the source folder over a number of weeks and it is not ascertainable when the final one will arrive. The users want to use a trigger file (i.e. the arrival of a spefic named file in the folder e.g. trigger.txt) to cause flow to start. My first two thoughts were using a first ListFile processor as an input to a second, or the input to an ExecuteProcess processor that would call a script to start the second one, however, neither of these processors accept an input, so I am a bit stumped as to how I might achieve this, or indeed if it is possible with NiFi. Has anyone encountered this use case, and if so how did you resolve it?
It's my understanding that most file IO operations are implemented in the kernel, such as CRUD, move or remove. However file copy is not implemented as a kernel level API.
In order to detect a file copy in the kernel one will need to use heuristics approach (discussion on this approach), e.g. as detect file reads, file creates and file writes from the same user with the same file name, but different paths.
Why copy is a user land operation?
First, because caring about whether or not two different files have the same content, where one file's content is copied directly from the other, is a user-space concern that has no logical reason to exist inside a kernel.
At best.
Bytes are bytes.
Second, how would the kernel distinguish copying a file between what are just two different file descriptors? See the man page for sendfile(). Why should the kernel track if the calling user called sendfile() to send the contents of a file to a TCP socket to who-knows-where or to another file?
Third, even if the kernel tracked copying a file, what on God's good Earth would it do with such data?
If you care about such file copy events, set up auditing.
I try to change the path of saving .csv file to C drive (the main dir).
Here the current code:
y="\"";
yy="\\";
Patch = "Csv_Files"+x2+Symbol()+x2;
I want the file that created to be rather saved in C drive ( the main dir ) instead in C:\Users\username\AppData\Roaming\MetaQuotes\Terminal\*********************\MQL4 dir.
How I can do that?
Thanks!
Short version
In pure-MQL4 no one can. MQL4 a-priori sand-boxes all fileIO to take place just in subdirectories of Terminal/MQL4/Files, resp. Tester/Files ( in case of testing a code inside a Strategy Tester ).
Still how to do that?
For security reasons, working with files is strictly controlled in the MQL4 language. Files with which file operations are conducted using MQL4 means, cannot be outside the file sandbox.
If FILE_COMMON is specified among flags, the file is opened in a shared folder for all MetaTrader 4 client terminals ( another magic ).
Nevertheless, you can setup distributed processing and orchestrate fileIO operations to be performed externally, via an unrestricted process and setup a peer-to-peer messaging or other DLL-based heterogenous distributed programming solution to escape from the box and write files wherever you need, even on a completely opposite side of the Earth ( remote logs et al ).
Is there a tool which can take 1000 Seperate HL7 Messages and combine them into a single document for 7edit? I need to run a test, and if I can do one document and choose send all, it will be better than me running it manually for each of these 1000 messages.
Yes, There exist a way to combine those messages in a single file. You can do that using any integration engine, I will take Mirth in this case.
Follow these steps in sequential order
Download Mirth Connect from here using the .exe installer (in case you don't have it).
Setup your account and do initial configuration on your local system.
Create a Channel called Appending Channel, put Source inbound and outbound connector as HL7v2.x.
Go to Source Tab, Put Connector type as File Reader. Give the location of the directory where your messages will reside(D:\x\read in my case). Make sure you have the directory shared
You can make Delete file after read as a Yes, which will prune the files after they are read from this location.If you do a NO, then specify where you want to move those files to.
Put Process Batch files as a No.
Go to Destinations tab, create a Destination called as Appender and make it a File Writer type.
Give the directory(D:\x\Output in my case) where your final file will be placed.Give the file name as final.txt.
Choose Append on the file exists tab.
In Template, Drag Raw Data from the list on the right hand side, and put it here or else what you can do is type ${message.rawData} in the template section.
Save Channel and Deploy it.
Place all your messages in the read folder (mentioned above), and wait for Mirth to poll the folder (default setting is 1000 ms).
Once that is done, go to final.txt to see all the messages appended in the same file.
The downside is that even though this process is 100 percent working, the message thus appended will not be seperated by any means. So it will look like below
|2688684|||||||||||||||||||||||||199912271408||||||002376853MSH|^~\&|EPIC|EPICADT|
^ End of first message
You don't need any tool for that. 7edit is able to read multi-message files. You just need to append each message into one single text file like this (two ADT messages):
MSH|^~\&|SystemA|CompanyA|SystemB|CompanyB|20121116122025||ADT^A01|101|T|2.5||||||UNICODE UTF-8
EVN|A01|20130823080958
PID|||1000||Lastname^Firstname
PV1||I
MSH|^~\&|SystemA|CompanyA|SystemB|CompanyB|20121116122026||ADT^A01|102|T|2.5||||||UNICODE UTF-8
EVN|A01|20130823080958
PID|||1000||Lastname^Firstname
PV1||I
Open this file with 7edit and you will see this (multiple messages):
Now you can send all messages at once by pressing on Send and then select All Messages:
It is that simple - no other tool necessary (just to make the append in one file maybe)
You could also try to use HL7Browser (www.nule.org), a tool that is similar to 7Edit, with less features but free.
You should be able to open many single HL7 messages files, HL7Browser will cache them in its viewer and should allow you to save them all to a single file.
Hope helps
Davide
if you have multiple HL7 files in one folder and want to combine them into 1 hl7 file, you can do following:
create a batch file in this folder named combine.cmd
write following into this batch file
del combined.hl7
for %%f in (*.hl7) do type "%%f" >> combined.hl
move combined.hl combined.hl7
run this batch file
result: all hl7 files in this folder are combined into a single file called "combined.hl7"
If I'm writing a simple text log file from multiple processes, can they overwrite/corrupt each other's entries?
(Basically, this question Is file append atomic in UNIX? but for Windows/NTFS.)
You can get atomic append on local files. Open the file with FILE_APPEND_DATA access (Documented in WDK). When you omit FILE_WRITE_DATA access then all writes will ignore the the current file pointer and be done at the end-of file. Or you may use FILE_WRITE_DATA access and for append writes specify it in overlapped structure (Offset = FILE_WRITE_TO_END_OF_FILE and OffsetHigh = -1 Documented in WDK).
The append behavior is properly synchronized between writes via different handles. I use that regularly for logging by multiple processes. I do write BOM at every open to offset 0 and all other writes are appended. The timestamps are not a problem, they can be sorted when needed.
Even if append is atomic (which I don't believe it is), it may not give you the results you want. For example, assuming a log includes a timestamp, it seems reasonable to expect more recent logs to be appended after older logs. With concurrency, this guarantee doesn't hold - if multiple processes are waiting to write to the same file, any one of them might get the write lock - not just the oldest one waiting. Thus, logs can be written out of sequence.
If this is not desirable behaviour, you can avoid it by publishing logs entries from all processes to a shared queue, such as a named pipe. You then have a single process that writes from this queue to the log file. This avoids the conccurrency issues, ensures that logs are written in order, and works when file appends are not atomic, since the file is only written to directly by one process.
From this MSDN page on creating and opening Files:
An application also uses CreateFile to specify whether it wants to share the file for reading, writing, both, or neither. This is known as the sharing mode. An open file that is not shared (dwShareMode set to zero) cannot be opened again, either by the application that opened it or by another application, until its handle has been closed. This is also referred to as exclusive access.
and:
If you specify an access or sharing mode that conflicts with the modes specified in the previous call, CreateFile fails.
So if you use CreateFile rather than say File.Open which doesn't have the same level of control over the file access, you should be able to open a file in such a way that it can't get corrupted by other processes.
You'll obviously have to add code to your processes to cope with the case where they can't get exclusive access to the log file.
No it isn't. If you need this there is Transactional NTFS in Windows Vista/7.