Jim Chappell wrote:
IBM HTTP Server is based on the Apache HTTP Server (httpd.apache.org),
developed by the Apache Software Foundation.
Also know as IHS
1: http://www-01.ibm.com/software/webservers/httpservers/
or
2:
http://www-03.ibm.com/servers/eserver/zseries/zos/unix/ported/ihs/index.html
There is a lot of confusion and mis-information about this,
mostly due to IBM's messing about with names and words.
John Boylston, who recently retired from IBM, was my
primary source for insights into CGIs and the IBM servers.
Here are some excerpts from our correspondence:
July, 2006:
"...the current IBM HTTP Server for z/OS and IHS for z/OS Powered by Apache,
which MAY be available late this year. There are a number of enhancements
over the non-z/OS versions of the Apache server "
August, 2006:
"You might also look at http://www.w3.org/, which has the source code for
the ancient CERN server, which was the ancestor of today's z/OS server
(but soon to be supplemented on z/OS by an Apache-based one)."
March, 2007:
"The z/OS version of the Apache server, at the Apache level 2.0.47, is
currently available as a feature of WebSphere 6.1, just in the latest
WebSphere fixpack. Its official name is IBM HTTP Server (IHS) for
WebSphere Application Server (Version 6.1)."
October, 2007:
"The plug-in for IHS for WebSphere (the Apache-based HTTP
Server, on z/OS or elsewhere) is aware of this proxying activity"
April, 2008 (to the MVS-OE list):
"The Apache-based IHS for z/OS is currently a part of the WebSphere
product, though there is some discussion of making it separately
available.
It does not have WLM capabilities (that is, no Queue manager - Queue
server support as in the old server), but it does have SAF authentication
and SAFRunAs abilities.
I have a document describing the conversion of the old CERN-based
directives to the Apache-based ones. If you are interested, send me a note
offline from the Forum."
August, 2008:
"Unfortunately, the term "IHS", for "IBM HTTP Server", is used for both
products, but it is used mostly for the Apache-based one."
[by "both products", he means the free HTTP server and
the Apache server that is a WAS plug-in, now also available
separately for free]
[he goes on...]
"Advantages of the Apache-based server:
- It has better stuff. It has had the attention of hundreds of developers,
who have addressed issues of conformance to protocol, resistance to
attacks, and so on.
- It is the most widely used HTTP server.
- If your shop has been running Apache on other platforms, then they know
how to configure it, and how to write modules for it. Porting a module
from one platform to another is usually pretty easy.
- It is at the beginning of a long life on z/OS. The old server for z/OS
does not have a sunset date, but it could happen.
- It has many more options for configuring. Some of the things you used to
have to do in a module (GWAPI) in the old server can be accomplished with
a directive in Apache/IHS.
- It has many more exit points where your own modules can get control.
- It has the ability to listen on more than 2 ports.
- It has support for SSL proxy connections to content servers.
- It has support for many other features that are missing in the old
server.
Advantages of the old server:
- It has many features especially for z/OS, such as MVSDS and WLM. The WLM
support gives it scalability with ability to classify the work, while
Apache's scalability technique lacks the ability to classify the work. By
classify, I mean the ability to make certain requests run on certain
servers, and to regulate the creation/destruction/priority of servers of
each class with different policies.
- If you wrote and compiled your own modules 10 years ago, chances are
99.9% that they will still work without recompiling.
- You don't have to buy WebSphere to get it. So far, IHS/Apache is part of
WebSphere.
- If IBM announces a sunset date for withdrawal of support, we will still
support it for 2 to 5 years.
- It is written in 31-bit code. The new server is available only in a
64-bit version. This has posed a problem for some customers, who interface
to z/OS functions which have only a 31-bit interface. One example is the
Catalog Search Interface.
I could go on, but you get the idea."
February, 2009:
"Most lines that were previously set in the httpd.envvars file in the
classic z/OS webserver (unfortunately known sometimes as "DGW") can now be
set in the envvars file for IHS (the Apache-based server).
The difference is that the old httpd.envvars file used simple name=value
pairs, while the IHS envvars file is a script, so the name=value pairs
should be in the form of commands, such as "export..."."
Kind regards,
-Steve Comstock
The Trainer's Friend, Inc.
303-393-8716
http://www.trainersfriend.com
z/OS Application development made easier
* Our classes include
+ How things work
+ Programming examples with realistic applications
+ Starter / skeleton code
+ Complete working programs
+ Useful utilities and subroutines
+ Tips and techniques
==> Check out the Trainer's Friend Store to purchase z/OS <==
==> application developer toolkits. Sample code in four <==
==> programming languages, JCL to Assemble or compile, <==
==> bind and test. <==
==> http://www.trainersfriend.com/TTFStore/index.html <==
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