Re: Use of the IFS

Adam - one of the best ways, IMO, to spend time on New Year's (NOT!) is to get the IFS Concepts manual - I posted it a few days ago, but here it is again. There are even sections on why you'd want to use it, but it's kind of typical IBM-ese. It'll tell you what a stream file is and everything else.

http://publib.boulder.ibm.com/infocenter/systems/scope/i5os/topic/ifs/rzaax.pdf

HTH
Vern

Joe Pluta wrote:

Adam West wrote:

Yes I am not that familiar with stream files actually. How are they used?

Adam, just to give you an inkling of what the IFS is about:

1. The IFS is a hierarchical system of folders within folders, much as you would see on a PC or on any Unix system (more like Unix, actually, as there are no "drives" like there are on PCs).

2. All of the objects we green screen dinosaurs are familiar with (libraries, files, members, programs, data areas, you name it) are stored in a folder called QSYS.LIB.

3. Many of the IBM folders start with (go figure!) the letter Q - those are typically folders that are very i specific.

4. Other standard folders have a distinctly Unix feel to them, with names like /tmp and /home.

5. Users on other machines can "map" drives or folders to your IFS. That is, you can create a folder on the IFS, and then other machines in your network can link to that folder and then access files on the folder as if that file were on their machine locally. No FTP required.

6. Similarly, a special folder name in the IFS, QNTC, allows you to access network-shared folders on other machines from the i. That is, the folder on some PC can be shared on the network and your i can read and write directly to that folder.

7. Typically, the files in the non-QSYS folders are treated as "stream files" which are "streams" of bytes - you usually don't deal with them as having fixed-length records and fields. Although that can happen, it's typically not done. Instead, you usually start reading the file at the beginning and run through it to the end - hence the term "stream".

8. The types of information stored in stream files includes but is certainly not limited to: simple text files, office documents of all persuasions, PDF documents, pictures in various formats (JPEG, PNG, etc.), and source and compiled objects for all manner of programming languages, from Java to C to PHP, and source for interpreted languages such as JavaScript and HTML.

The IFS allows Java programs and Unix programs running under PASE to access data natively, since those environments deal almost exclusively with stream files. Any structured data is accessed through a database engine, which typically also stores its data in stream files. For example, I've been writing some articles on using MySQL on the i, and when you create a table in MySQL it stores the data in stream files in the IFS, not in DB2 tables in the QSYS file system. APIs exist for us RPG folks to access that data as well, either in binary or in text format, and for the latter to convert between our beloved EBCDIC and the formats used in the IFS world (predominantly ASCII and Unicode).

Hope this gives you a little intro. Happy New Year!

Joe