Question about FileSystemProvider API in JDK7

[Pisarev, Vitaliy]

I appreciate the quick response. 

I looked at the code of PassThroughFileSystem, and I must say it underlines my point here. In case someone wants to interpose on the default provider, he has to write all this boiler plate code. 
And unless they are aware of the PassThroughFileSystem, they will probably not do it right. The point being that the mechanism is not friendly for extension by developers.

Since delegation is the only feasible method available, I wonder whether you have any plans for introducing facilities that will allow extension by inheritance, or put some other hooks in place?

The reason I am insisting is because I think that a file system abstraction is a very powerful concept and I would definitely like to know whether you are planning to invest in this in the future.

-----Original Message-----
From: Alan Bateman [mailto:Alan.Bateman at oracle.com] 
Sent: יום ב 21 אוקטובר 2013 10:55
To: Pisarev, Vitaliy; nio-dev
Cc: core-libs-dev at openjdk.java.net
Subject: Re: Question about FileSystemProvider API in JDK7

On 21/10/2013 06:30, Pisarev, Vitaliy wrote:
> Hello,
>
> I was directed to this list by Brian Goetz, I am a new member and I am not yet acquainted with how things go in these mailing lists.
> I am an SW Engineer and I am looking for some insight about the new FileSystemProvider API. I posted a question on SO:
>
> http://stackoverflow.com/questions/19425836/tweaking-the-behavior-of-t
> he-default-file-system-in-java-7
>
> I hope this reaches you and your answer reaches me back.
>
The service provider interface allows you to replace the default provider or interpose on it (see the FileSystems.getDefault docs for the details on how this is configured). When you interpose on the default provider then you have the opportunity to do your customization although it can be tricky to ensure that you get all the delegation right. As a starting point then look at the PassThroughFileSystem in jdk/test tree, this is a provider used by some of the tests and may be what you are looking for.

If on the other hand that you are looking for something at the lower level, say to intercept calls to the operating system then there isn't anything in the APi for that.  To do customizations at that level requires using a native interposer library, or if Windows then it means using something like Detours [1].

-Alan.

[1] http://research.microsoft.com/pubs/68568/huntusenixnt99.pdf