Connecting DB2 to z/OS to Other DB2 Systems

For years DBAs have used IBM DB2 Connect to develop applications that run on Linux, Unix or Windows and connect to DB2 for z/OS. But what about connecting an application that runs on z/OS to DB2 running on a LUW system or even a separate z/OS system?

The drivers for connecting to other DB2 systems are available with DB2 for z/OS. To learn about these drivers and how to install them, see the DB2 10 for z/OS Application Programming Guide and Reference for Java.

(Note: As of DB2 Version 9.1, the JDBC/SQLJ Driver for OS/390 and z/OS is no longer supported. All Java application programs and Java routines that are currently written to work with the JDBC/SQLJ Driver for OS/390 and z/OS must be modified to work with the IBM Data Server Driver for JDBC and SQLJ -- formerly known as the DB2 Universal JDBC Driver. See the DB2 10 for z/OS Installation and Migration Guide to learn more about installing the IBM Data Server Driver for JDBC and SQLJ.)

Despite the growing need for mainframe pros to work with LUW environments, lack of awareness remains an issue. For instance, many people still don't realize that a Java application running on z/OS can be connected to a system with DB2 for LUW, or that a web-based application running on z/OS under UNIX System Services can be connected to another system with DB2 for z/OS.

A couple other relevant resources, starting with this list of IBM Data Server Driver for JDBC and SQLJ versions and DB2 for z/OS APARs. And to receive notifications about potential migration issues due to incompatible changes in DB2 10, you can track information APAR II14619 (DB2 V10.1 DDF MIGRATION INFOAPAR).

The point I was trying to make is that people still are not aware that you can connect a JAVA application running on z/OS to a DB2 running on LUW or a web based application running on z/OS under unix system services to DB2 for z/OS. I put the DB2-L comment in to show that even as of last month questions still come in asking is this possible.

 

Using File Reference Variables

DB2 10 for z/OS introduced support for reading and writing LOB and/or XML data to files using file reference variables. File reference variables allow large LOB or XML values to be inserted from or selected into files rather than host variables. This saves memory because applications aren't holding large XML or LOB values.

A related benefit of using file reference variables is that you avoid storing large XML/LOB values in host application working storage. The data bypasses the application storage and travels directly to the client file system and database server.  And by keeping the data out of the application storage, you avoid any limitations the application host language may place on working storage sizes. These languages supports file reference variables: C, C++, COBOL, PL/I, Assembler, REXX and Java. 

Do you have an application that takes advantage of DB2 10 for z/OS file reference variables? Please take a moment and post a comment about your experience.

zEC12: What’s in it for DB2 pros?

IBM recently announced the zEnterprise EC12 (zEC12), an enterprise system that provides cloud computing capabilities. Here's a nice overview, and here's Willie Favero dissecting the name.

The day of the zEC12 announcement, the IBM Redbook team released a draft titled, “IBM zEnterprise EC12 Technical Introduction."

I mention this publication because it cites three new features that I believe will improve DB2 processing. 

The first is the introduction of 2 GB page frames. This support means that the page size limit of 1 MB that's available in DB2 10 has grown by 2,048 times. IBM has this statement of direction:

• IBM plans for future maintenance roll-ups of 31- and 64-bit IBM SDK7 for z/OS Java to provide exploitation of new IBM zEnterprise EC12 features, including: Flash Express and pageable large pages, Transactional Execution Facility, Miscellaneous-Instruction-Extension Facility, and 2 GB pages.
• Beyond the existing DB2 support for zEC12, DB2 plans further enhancements designed to improve performance in two ways: 1) using pageable large (1 MB) pages and Flash Express and 2) enabling support of 2 GB pages

The second new feature is improved DB2 I/O response time based on changes to MIDAW and FICON channels. For more, see IBM Redpaper, “How does the MIDAW Facility Improve the Performance of FICON Channels Using DB2 and other workloads?”

The final new feature involves improvements in Java execution on z/OS. Java is planned to exploit a significant set of the new instructions available in zEC12. Here's IBM statement of direction on this:

"IBM SDK7 for z/OS Java is available for use by IBM middleware products running Java, such as IBM IMS 12, IBM DB2 10 for z/OS, and the Liberty profile of IBM WebSphere Application Server for z/OS v8.5 and is planned for use by a future release of CICS Transaction Server for z/OS."

IBM's intent to provide future maintance roll-ups of 31- and 64-bit SDK7 for z/OS Java (detailed above) also applies here.

I look forward to learning more about Flash Express, pageable large pages and the other new capabilities to come.

So is your company moving to zEC12? What's driving the decision for your upgrade?

DB2 for LUW Security Alert

IBM just published this security bulletin aimed at DB2 for LUW users, "Buffer Overflow Vulnerability in IBM DB2 Java Stored Procedure Infrastructure":

"DESCRIPTION: The IBM DB2 products listed... contain a security vulnerability that could allow an authenticated user to exploit a vulnerability in DB2's Java Stored Procedure infrastructure to cause a stack-based buffer overflow and possibly attain remote code execution.

"To exploit the vulnerability the malicious user would need:
1. Valid credential to connect to database
2. CONNECT privilege on database
3. A Java stored procedure to which the user has EXECUTE privilege.

"If you do not have any Java stored procedures installed then you are not affected. To find the names of your Java stored procedures, execute the following SQL statement using the DB2 Command Line Processor (CLP):

SELECT ROUTINENAME FROM SYSCAT.ROUTINES WHERE LANGUAGE='JAVA'

"If you have no Java stored procedures installed then you would get back an empty result like the following:

 

ROUTINENAME
------------------------------------------------

0 record(s) selected. "

 

Initially I didn't think this posed a significant risk, because only an authorized user would be able to get far enough to cause a problem. However, most security breaches happen with people on the inside, so this should be taken seriously. The link above provides details, including a list of affected platforms and a link to the patch that must be installed to correct the vulnerability.

I didn't see any mention of DB2 for z/OS. If you're aware of any security vulnerabilities for DB2 for z/OS, please post a comment.

DB2: What Interests You?

A little more than three years ago, I started this blog with IBM Systems Magazine. My primary goal then was to tell you about the cool new features in DB2 9. In fact, my first post, dated July 16, 2007, explained how to use Universal Table Space.

Since then, I've written about everything from database administration and SQL to Java and XML to IBM Redbooks and the state of the mainframe. And, with DB2 10 now in beta, most recently I've been writing about new features to come.

All of these things interest me. But I'm also interested in what you think.

I know that this is a diverse group of readers. So, in an effort to learn what you really want to read about, I'm requesting your feedback.

I'm not exaggerating when I say I love hearing from you. Reader questions and comments not only give me things to write about, they broaden my perspective on DB2 and the mainframe. So, please: If there's a specific area of DB2 you'd like to see covered, let me know. You can e-mail me, or just post in Comments.

I look forward to hearing from you.

Batch Modernization on z/OS

Much has been written in blogs and z/OS forums about the need to hire a younger generation to take over for the aging workforce. The reality is that fewer computer science graduates are wanting to work on the mainframe because it wasn't taught to them -- and because the mainframe wasn't part of their curriculum, they view it as outdated technology and a career dead-end.

Now, companies like IBM and CA are introducing products that are geared toward this new Xbox and PlayStation generation. And, just as Windows replaced DOS, you'll see the web browser replace ISPF and TSO. This will make the transition from developing and working on Windows and Internet Explorer much smoother and more familiar. However, while all this is great for the online transaction processing systems, what about the boring batch systems that are written in COBOL and execute using Job Control Language (JCL)? How can these batch-running programs send e-mail or save reports in PDF format so they can be shared and used by modern Web-based applications?

The recently released IBM Redbook, "Batch Modernization on z/OS," attempts to answer these questions. The publication explains why we need to implement new technologies like Java and PHP on z/OS. It also provides sample DB2 DDL and source code for implementing sample applications.

From my reading, I learned the interesting fact that some standard Java APIs are available to help you interact with z/OS services. For example:

•    MVS dataset and VSAM access to interact with z/OS specific data
•    Condition code passing for integration of Java batch jobs into z/OS job nets
•    z/OS Catalog search
•    Interaction with the MVS Console
•    Conversion of COBOL/ASM data types to Java types
•    Invoking DFSORT to effectively sort data
•    Access to z/OS Access Method Services (IDCAMS)
•    RACF APIs to integrate Java into the z/OS security model
•    Writing of Logstreams (e.g. as an Appender to LOG4J)
•    Submission of Jobs from Java

Since batch jobs do a lot with reading, writing and sorting sequential and VSAM files, it makes sense to provide these services available to Java programs. The world is changing very quickly, and the way we build and support applications on z/OS is changing just as rapidly.

As one who's repeatedly expressed his love of Redbooks, let me tell you that, from what I've read, "Batch Modernization on z/OS" is one of the most valuable Redbooks available to both traditional mainframe personnel and LUW (Linux, UNIX, Windows) pros who are getting started with z/OS. If your company is modernizing its batch systems, you owe it to yourself to download and review this publication.

And, if you or your company has already gone down the road of modernization, please take a moment to post a comment. It's always nice to learn from those who've gone through the process.

Call for Requirements: IBM Java SDK for z/OS

IBM would like to hear from you regarding your organization's use of Java stored procedures. Before you can answer these questions, you'll need to know if you have the IBM SDK for z/OS Java 2 installed on all of your z/OS systems. If you have Java stored procedures, then you have it. If you're not sure, ask your systems programmer--or run this query, which will return a list of Java stored procedures:

SELECT SCHEMA, NAME, CREATEDBY
     , LANGUAGE, ROUTINETYPE
     , SPECIFICNAME, WLM_ENVIRONMENT
FROM SYSIBM.SYSROUTINES
WHERE LANGUAGE = 'JAVA';

Here are the questions:

• If YES (the SDK is installed), what level(s) of the SDK are installed?
• If NO (the SDK is NOT installed), do you foresee any problems installing the SDK as a prerequisite for a DB2 for z/OS tool product?
• Do you have zAAPs on the LPARs you would run the tools on?
• Any comments about our using Java on z/OS?

Your feedback will help drive IBM's future directions in DB2 for z/OS tools development. Please send your feedback directly to Bryan Smith: [email protected] .