Level: Intermediate Gary Puchkoff (puchkoff@us.ibm.com), Senior Technical Staff Member, IBM
30 Aug 2006 Senior architect Gary Puchkoff answers your questions about WebSphere® Application Server for z/OS®.
Introduction
Senior architect and designer Gary Puchkoff covers how WebSphere Application for z/OS fits in with the rest of the WebSphere family and the unique exploitation of z/OS capabilities, which includes the System z™ Application Assist Processor (zAAP) for the Java™ processor. WebSphere for z/OS is the premier Java 2 Enterprise Edition (J2EE) and Web services application server for the mainframe. It is a complete programming model, compatible with WebSphere on other platforms while maintaining unique capabilities in the areas of security, transactions, and workload management.
Question: My company migrated from WebSphere Application Server for z/OS V4.0.1 to V5.1 and it was very time consuming. What is IBM® doing to improve the migration process?
Answer: The migration from V4.0.1 to V5 was more complicated than we would have liked. We have made improvements in a number of areas. First, we are now working very hard to ensure that we don't make incompatible changes to WebSphere. For example, the changes to scripting between V4 and V5 caused a lot of work to be done. In V5 and V6, we have maintained the same scripting support. Second, we have implemented a deprecation policy where we document all interfaces that are changing or going away within two releases of notice. These interfaces are documented in the WebSphere Application Server Information Center. After two releases, we will update the documentation when that interface is removed. Third, we have migration tooling built into the product to ease the transition from release to release. We now support migration even when you skip a release. Finally, we support mixed version cells when you are running WebShere Application Server ND. This means you can continue to run a V5.1 server by upgrading your deployment manager to V6.1, and create a new server at V6.1 while maintaining the V5.1 servers.
Question: We used WebSphere Application Server for z/OS V4.0.1 and found that migrating an application from WebSphere Application Server on Windows® was difficult. Not all the same APIs were supported. When is IBM going to make WebSphere Application Server for z/OS the same as on non-z/OS?
Answer: The support you are looking for is now in V6.0.2 and later. The implementation of WebSphere Application Server for z/OS is the same code base as on the non-z/OS platforms. WebSphere Application Server for z/OS continues to maintain a tight coupling to z/OS. We have not removed any exploitation of z/OS capabilities that were in the prior products. If you have an application that runs on WebSphere Application Server on Windows, you will find that it works the same on z/OS. There are going to be functions on Windows outside of the WebSphere programming model that may not be present on z/OS, just as there may be APIs on z/OS that are not present on Windows. As long as you stay within J2EE and the WebSphere documented APIs, you can be sure that the application will run.
Question: Can you give any news on when WebSphere Application Server for z/OS will support 64-bit?
Answer: When we announced WebSphere Application Server V6.1, we said we planned to deliver a version of z/OS that exploited 64 bit. z/OS 1.6 is a bi-modal operating system and it will run both 31-bit and 64-bit applications at the same time. So our WebSphere support for z/OS is being designed to support either 31-bit or 64-bit servers operating at the same time. You can upgrade your deployment manager and node agent to 64-bit, and define a new server as 64-bit while maintaining your other servers as 31-bit servers. This provides a granular migration path for customers to move to 64-bit support. With 64-bit support, you can specify a Java™ heap that is much larger. Customers typically find that about 1G is the largest Java heap that you can have on 31-bit z/OS. This support allows you to run 2G or larger. When we ship the z/OS 64-bit deliverable, we will also relax the 10MB IIOP message buffer limitation.
Question: Can z/OS reside in the same cell as non-z/OS?
Answer: Starting with V6.0.2, we support mixed platform cells with z/OS. This means you can have a z/OS node managed by a non-z/OS deployment manager, or you can have a z/OS deployment manager manage a non-z/OS server. This allows for more flexibility in maintaining a single cell. To do this, the security configuration must use the common security protocols between platforms, which is typically LDAP/LTPA and file based, or TAM based authorization. You also cannot have a cluster with a mixture of z/OS and non-z/OS servers. z/OS servers share data in a cluster using the z/OS coupling facility, which is not available to non-z/OS servers.
Question: Can you explain the benefit of zAAP processors when using z/OS?
Answer: zAAP processors are special purpose processors for use by z/OS. They only execute Java code. The idea is that since Java is a more CPU intensive language than others, we provide additional processor capacity by adding additional lower priced CPUs. These CPUs execute the Java portion of a Java application. Some Java applications will execute 50% of the time in Java, and others will execute 80%. It is very application dependent. IBM provides a mechanism to estimate this and help to determine the benefit of zAAPs for your applications. In addition to providing lower CPU cost, a zAAP's capacity is not included in the capacity of the machine. This means that when software is sold using a capacity based pricing metric, you may not have any increased software charges when you add an additional zAAP. So a zAAP may increase your overall capacity without increasing your software costs.
Question: Is there a plan for z/OS to support more granular administration permissions? We would like to limit developers to only installing applications in their own servers.
Answer: In V6.1, we added a new role called deployer. This role allows you to install applications in a server. We have also added support for more granular permissions. This is available in V6.1 through the scripting interface only. The administration console (GUI) does not yet support these more granular permissions. If you are limiting your developers to installing applications via scripting, then you can use this new support.
Question: We run in a sysplex and have multiple copies of WebSphere Application Servers for availability. Sometimes we need to do maintenance on one of the LPARs. Is there any way to temporarily have WebSphere z/OS stop receiving work?
Answer: Yes, we have added an operator command called pauselisteners/resumelisteners. You can specify this on the z/OS modify command, and there is also a MBEAN interface. When you issue pauselisteners, the z/OS server disconnects from all inbound work requests (HTTP, IIOP and MDBs). Then you can do whatever maintenance you need to do. When you are done, you can issue a resumelisteners to start accepting work again. Generally, the workload balancing code will recognize this, and work will go to other cluster members. This avoids having to stop WebSphere and restart it, which can be a time consuming activity.This support was shipped in WebSphere Application Server V5.1 and later.
Question: WebSphere on z/OS can use IHS powered by Apache on non-z/OS platforms, but needs IHS powered by Domino® on z/OS. Are there any plans to support an IHS powered by Apache on z/OS?
Answer: Yes, as part of the V6.1 announcement, we mentioned that we plan to deliver an IHS powered by Apache on z/OS. This will be consistent with all other supported WebSphere platforms.
Question: The install process for WebSphere on z/OS is very different from WebSphere on non-z/OS. Are there any plans to change this?
Answer: WebSphere on z/OS has to fit into the z/OS installation process, which is based on SMP/e and ISPF, as well as the installation process for WebSphere. In V6.1, we changed a few things. First, we no longer ship OBJ decks, we now ship executables. The value here is that it cuts the SMP/e installation time by a significant amount. Second, we now ship a tool as part of the Application Server Toolkit (AST) called the z/OS profile management tool. It is an Eclipse-based application that is similar to the PMT shipped for non-z/OS platforms. It runs on Linux or Windows and produces the same batch jobs as the ISPF dialogues. In addition, it supports the same response file format as non-z/OS that allows "silent" installs.
Resources
About the author  | 
| | Gary Puchkoff is a Senior Technical Staff Member, architect and designer of WebSphere Application Server for z/OS. He is responsible for the overall product with a focus on performance and security. He maintains close relationships with customers through regular meetings with the z-Series Business Leaders Council, and customer advocacy engagements. |
Rate this page
| 
