What is AS/400?

Baredor

Seeing "Knowledge of AS/400 helpful" and like statements on the job engines and was wondering what this meant.

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squawk1500

An AS/400 is an IBM mainframe computer. You can check them out on IBMs website or look them up on ebay.

keatron

AS 400 is a IBM platform server first released in the late 80's. I use to support one (working for a police department). If you've heard of the IBM iSeries, and i5 platforms, that's the newer AS 400 stuff. It has an object oriented integrated relational database.

NPA24

So are these kind of IBM servers popular today? I started to see those in many job postings when I was job hunting and always wondered why these companies have these legacy servers still in use. Is there really a pro to still using the AS 400?

keatron

Well, they are still in use today (just as NT 4 based networks are). As I pointed out before IBM iSeries servers are the newer AS 400 systems. A similar comparison would be NT 3 platforms to 2000/2003 platforms. Depending on who you're talking to and where you are, the term "AS 400" is sometimes used generically to elude to that class and function of IBM servers. Some companies are replacing this with a .NET and SQL server solution.

kjpou1

Actually the IBM AS/400 is classified as a midrange, the S/390's are mainframe ( work and develop on both). The predecessor of the AS400 was the system 38. It is for medium sized companies and when hooked/networked together can provide very high transaction processing throughput. They are extremely scalable, flexible and high availability platforms.

As has been mentioned IBM has produced a server series, the iSeries, that allows you to host AIX,windows and linux environments plus a wide range of other services. The newer models, not just the servers, run a linux partition for Apache, java, dns and dhcp well let's just say a very wide range of services that linux is capable of. This was IBM's way of getting into the lower end markets. Kind of sitting between companies that were outgrowing their window environments but were still not ready to pay the price tag of there main AS/400 platforms. The larger models are not used much as servers but more for running the the core applications of a business. What most companies will do is buy one of the iSeries server machines to run their webpages and such so that the production environment will not be touched from outside thus providing a level of security there as well.

The database engine on an AS/400 was specially built DB2 engine to take advantage of their 64-bit processing platforms. As a database server it is extremely flexible, fast as hell with fault tolarence built in. Very transaction oriented database access. It actually provides two type of access, one direct by key access and/or SQL query access. Of which both can be interchanged.

It supports a number of programming languages C, C++,RPG, COBOL and MI(machine instruction more or less assembly language for the AS400 which is not usually used).

The interface to the system uses a modified telnet data stream called the 5250 data stream which means it uses port 23 for connections unless using SSL connections.

As far as legacy is concerned, the AS400 is not considered legacy by any means. Many campanies use the system especially banks and finacial institutions. They might have a mainframe for processing all the transactions but usually there is an AS400 providing all the information and transaction processing to the mainframe.

Well I could keep going but this is probably more information than you were looking for.

A couple of links here:

http://www.ddj.com/documents/s=875/ddj0065f/
http://www-1.ibm.com/servers/eserver/iseries/about/why.html

The article below gives some background on why the as400 is thought of the way it is:

http://www-1.ibm.com/servers/eserver/iseries/pdf/iSeries_Dierckx_0405.pdf

And of course the main IBM site pages.

Regards

Kenneth

Baredor

Great to know. Thanks everyone.

NPA24

Those were pretty good replies. Thanks everybody for all the great information about the AS400!

PCHoldmann

I work in an AS/400 / iSeries environment, and at a database server the things are great. We have 6 stores that connect to one server, and I think we had 1 instance of unplanned downtime in the past 5 years, and i think that was human error or an act of nature, I forget the details (Plus one time that IBM called us and told us that the macine had sent them a message that one of the drives was on the way out, IBM had a tech come out before we were open and replace the drive

). They are different from most systems that you would work with on a normal basis, 5250 is a screen at a time protocol, meening that whatever you are filling out (i.e. an order form) is displayed as a full screen, the data you type if buffered, and sent when you hit enter. Standard telnet is charachter at a time: press a key, the keystroke is sent to the server, and echoed back to you. The AS/400 is also where you would run into twinax cabling, to connect dumb terminals, but that is going away in favor of 5250 telnet sessions. Another benefit: No known viruses.

shadown7

Real good information on AS/400!

mikey_b

It cn be hard to find training for though... It is something I'd much rather learn about in a lab environment than books. Very complex stuff, but the complexity pays off, Big Financial Institutions love IBM.

kjpou1

PCHoldmann wrote:

They are different from most systems that you would work with on a normal basis, 5250 is a screen at a time protocol, meening that whatever you are filling out (i.e. an order form) is displayed as a full screen, the data you type if buffered, and sent when you hit enter. Standard telnet is charachter at a time: press a key, the keystroke is sent to the server, and echoed back to you. The AS/400 is also where you would run into twinax cabling, to connect dumb terminals, but that is going away in favor of 5250 telnet sessions. Another benefit: No known viruses.

Yes correct the 5250 emulator buffers the data and sends it back to the host in an interactive communications environment. Meaning there is really no interaction between the client and the host until you tell it to communcate with a function/aid key.

You can also connect to the AS400 with a simple telnet client as well via port 23 but not all the function keys will be active so the user experience will be pretty much bland. Thus the use of port 23 to communicate with the host AS/400. There is a negotiation that takes place on connection to an as/400 telnet session, one of which is a device capabilities query. You then send back whether you are a normal telnet client, 5250 client or even 3270. The controller does the translation of the correct protocol in use. The interfacing controller is really quite intelligent and the 5250 data streams are quite horrific. Which brings me to another little tidbit of information being that AS/400's are EBCDIC based not ASCII.

The other thing that is mentioned here that not a lot of people know is how actual telnet works. It is an echo type of protocol which is great to know and explained above.

As for learning you can find quite a lot of time share AS400 sites on the internet.

Here is one (am not associated with them in anyway):

http://www.netshare400.com
http://www.timeshare400.com

They usually all provide learning documents as well. Just to see what I am talking about with telnet you can do the following from the command line.

>telnet www.netshare400.com

You will be connected with a telnet session to an actual AS400 session presenting an interactive signon session.

If you plan on using one of these timeshares from the house to play around with you will need a 5250 emulator. The commercial ones cost an arm and a leg but there are some really good free ones out there. Am sure the free ones are more than enough to get you started because I use one for production environments.

linux and windows (basic 5250 emulation):

http://tn5250.sourceforge.net

A java based one (of which a new version will be available the weekend) that also provides a lot of extra options and a file download feature to convert data bases into specific format such as MS excel.

http://tn5250j.sourceforge.net

Mochasoft has a basic trial version and is not that expensive at 25$ for a registerd version:
www.mochasoft.com

IMHO the free ones mentioned above are better than the mochasoft one.

Hope this helps

Kenneth

PCHoldmann

One other source of information is from IBM at http://publib.boulder.ibm.com/pubs/html/as400/infocenter.html, I am not sure if there is any kind of "Getting started" or anything, but it is the full IBM documentation for the AS/400 / iSeries / i5.

garv221

Baredor wrote:

Seeing "Knowledge of AS/400 helpful" and like statements on the job engines and was wondering what this meant.

WOW...I use to run one back in 2000..The first job I ever had, I had a program called Aspelle Everywhere (ahead of its time) that would use SSL web browser to VPN into the As/400 mainframe. I just remember that being a big deal. They don't make Aspelle Everywhere anymore...

JDMurray

When you want to know what something is, look it up in the Wikipedia:

http://en.wikipedia.org/wiki/AS/400

garv221

jdmurray wrote:

When you want to know what something is, look it up in the Wikipedia:

http://en.wikipedia.org/wiki/AS/400

Nice, very nice.