my recent reads..

An MQ and OCCI Demo

A little while ago I got to dust off my C++ skills for a project that was to use Oracle Database (via OCCI) and also Websphere MQ. Oracle and IBM already make a range of demos available, but they are mostly all very closely scoped on one feature only. Since I didn't find anything that included all they key concepts in a full working demo, I put together a combined OCCI/MQ demo to do the job (available for download as a tar/gzip file here: occidemo.tgz, see the readme.txt for details).

A couple of key things demonstrated:

  1. C++ (OCCI) Oracle database access
  2. Transparent Application Failover (TAF) notifications in C++ (OCCI)
  3. Building a C++ application with MQ and OCCI support
  4. Using makefile flags to build either with full or a "stub" database library class
The demo is written for Linux (32 or 64 bit) and has been tested with Oracle Database 10g Server, Oracle 10g Instant Client, and IBM WebSphere MQ 6.0.

The diagrams below give a simple exposition of how the demo is structured. The executables "mqproducer" and "mqconsumer" are MQ clients shuttle messages back-and-forth via queues. For each message sent by "mqproducer", a reply is expected from "mqconsumer". The readme.txt in the archive contains fairly detailed coverage of how to run the demo.

If the sample is built with full database support, then a "dblibrary" is linked in that will persist each message to database (and the dblibrary_test program can be use to test the operation).
If the sample is built with a database "stub", then a dummy database library is substitued, and the programs a built without any Oracle Database support linked in at all. This can be useful when just wanting to focus on the MQ aspects in isolation.

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The top 10 dead (or dying) computer skills

I try to avoid postings that just refer you to other blogs or articles, but I've succumbed. ComputerWorld's The top 10 dead (or dying) computer skills prompted a bit of nostalgia. I scored 91% [giving myself 1% for the time I bought a book on COBOL while at uni ... and had the good sense to take it no further than that!!].

OS/2 brings back memories, of which I was also reminded when I first checked out Google's code search and found some of my 1995 OS/2 code lying around! [NB: these days, I look at this code and shudder "Eek!... buffer overflow vulnerability!!" ... security just wasn't front of mind back then! ]. But it also reminds me of how much thought I put into the decision to adopt C++ on OS/2. It very much felt like "this is a decision that I'll live with for years". But 12 years later, in 2007, that decision-making process seems so naive and foreign. Now it is routine to dabble in a couple of scripting languages, some Java, even some C++. The right (or most fun) tool for the job, right?

If I could say "Programming Language Bigotry" is a skill (some people certainly practiced and honed it like it was), then boy am I glad it seems to be a thing of the past and perhaps it deserves to be #1 in this list!

After a brief post-dot-boom hiatus, the drammatic rate of evolution is certainly back, spurred on by Web 2.0 hype. The rate of technological change has indeed become so "normal" that a top 10 list hardly scratches the surface. Personally I would have voted for int 21h. I'm sure generations to come will have absolutely no idea what that means, but for me and presumably many others, I can sum up a year of computer science with that very phrase.

For many (myself included), To Be Alive is To Be Learning and vice versa. The new religion if you will. "Lifelong learning" or "learning for life" are too trite and miss the essential truth.

Other may say that to be continuously learning is to be in a perpetual state of childhood. Look at some of the toys we are learning about and maybe they have a point!

Postscript: I just re-listened to a WebDevRadio Episode 18 which reminded me that Coldfusion is not dead!! At least according to the guys at Mach ii..
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Monitoring log files on Windows with Grid Control

The Oracle Grid Control agent for Windows ( is missing the ability to monitor arbitrary log files. This was brought up recently in the OTN Forums. The problem seems to have been identified by Oracle earlier this year (Bug 6011228) with a fix coming in a future release.

So what to do in the meantime? Creating a user defined metric is one approach, but has its limitations.

I couldn't help thinking that the support already provided for log file monitoring in Linux must already be 80% of what's required to run under Windows. A little digging around confirmed that. What I'm going to share today is a little hack to enable log file monitoring for a Windows agent. First the disclaimers: the info here is purely from my own investigation; changes you make are probably unsupported; try it at your own risk; backup any files before you modify them etc etc!!

Now the correct way to get your log file monitoring working would be to request a backport of the fix from Oracle. But if you are brave enough to hack this yourself, read on...

First, let me describe the setup I'm testing with. I have a Windows agent talking to a Linux Management Server. Before you begin any customisation, make sure the standard agent is installed and operating correctly. Go to the host home page and click on the "Metric and Policy Settings" link - you should not see a "Log File Pattern Matched Line Count" metric listed (if you do, then you are using an installation that has already been fixed).

To get the log file monitoring working, there are basically 5 steps:

  1. In the Windows agent deployment, add a <Metric NAME="LogFileMonitoring" TYPE="TABLE"> element to $AGENT_HOME\sysman\admin\metadata\host.xml

  2. In the Windows agent deployment, add a <CollectionItem NAME="LogFileMonitoring"> element to $AGENT_HOME\sysman\admin\default_collection\host.xml

  3. Fix a bug in $AGENT_HOME\sysman\admin\scripts\

  4. Reload/restart the agent

  5. In the OEM console, configure a rule and test it

Once you have done that, you'll be able monitor log files like you can with agents running on other host operating systems, and see errors reported in Grid Control like this:

So let's quickly cover the configuration steps.

Configuring metadata\host.xml
Insert the following in $AGENT_HOME\sysman\admin\metadata\host.xml on the Windows host. NB: this is actually copied this from the corresponding host.xml file used in a Linux agent deployment.
<Metric NAME="LogFileMonitoring" TYPE="TABLE">
<ValidMidTierVersions START_VER="" />
<CategoryProp NAME="OS" CHOICES="Windows"/>
<Label NLSID="log_file_monitoring">Log File Monitoring</Label>
<ColumnDescriptor NAME="log_file_name" TYPE="STRING" IS_KEY="TRUE">
<Label NLSID="host_log_file_name">Log File Name</Label>
<ColumnDescriptor NAME="log_file_match_pattern" TYPE="STRING" IS_KEY="TRUE">
<Label NLSID="host_log_file_match_pattern">Match Pattern in Perl</Label>
<ColumnDescriptor NAME="log_file_ignore_pattern" TYPE="STRING" IS_KEY="TRUE">
<Label NLSID="host_log_file_ignore_pattern">Ignore Pattern in Perl</Label>
<ColumnDescriptor NAME="timestamp" TYPE="STRING" RENDERABLE="FALSE" IS_KEY="TRUE">
<Label NLSID="host_time_stamp">Time Stamp</Label>
<ColumnDescriptor NAME="log_file_match_count" TYPE="NUMBER" IS_KEY="FALSE" STATELESS_ALERTS="TRUE">
<Label NLSID="host_log_file_match_count">Log File Pattern Matched Line Count</Label>
<ColumnDescriptor NAME="log_file_message" TYPE="STRING" IS_KEY="FALSE" IS_LONG_TEXT="TRUE">
<Label NLSID="host_log_file_message">Log File Pattern Matched Content</Label>
<QueryDescriptor FETCHLET_ID="OSLineToken">
<Property NAME="scriptsDir" SCOPE="SYSTEMGLOBAL">scriptsDir</Property>
<Property NAME="perlBin" SCOPE="SYSTEMGLOBAL">perlBin</Property>
<Property NAME="command" SCOPE="GLOBAL">%perlBin%/perl</Property>
<Property NAME="script" SCOPE="GLOBAL">%scriptsDir%/</Property>
<Property NAME="startsWith" SCOPE="GLOBAL">em_result=</Property>
<Property NAME="delimiter" SCOPE="GLOBAL">|</Property>
<Property NAME="warningStartsWith" SCOPE="GLOBAL">em_warning=</Property>

In the top TargetMetadata, also increment the META_VER attribute (in my case, changed from "3.0" to "3.1").

Configuring default_collection\host.xml
Insert the following in $AGENT_HOME\sysman\admin\default_collection\host.xml on the Windows host. NB: this is actually copied this from the corresponding host.xml file used in a Linux agent deployment.
<CollectionItem NAME="LogFileMonitoring">
<IntervalSchedule INTERVAL="15" TIME_UNIT = "Min"/>
<MetricColl NAME="LogFileMonitoring">
<Condition COLUMN_NAME="log_file_match_count"
MESSAGE="%log_file_message%. %log_file_match_count% crossed warning (%warning_threshold%) or critical (%critical_threshold%) threshold."
MESSAGE_NLSID="host_log_file_match_count_cond" />

A bug in
This may not be an issue in your deployment, but in mine I discovered that the script had a minor issue due to an unguarded use of the Perl symlink function (a feature not supported on Windows of course).

The original code around line 796 in $AGENT_HOME\sysman\admin\scripts\ was:
my $file2 = "$file1".".ln";
symlink $file1, $file2 if (! -e $file2);
return 0 if (! -e $file2);
my $signature2 = getSignature($file2);

This I changed to:
my $file2 = "$file1".".ln";
return 0 if (! eval { symlink("",""); 1 } );
symlink $file1, $file2 if (! -e $file2);
return 0 if (! -e $file2);
my $signature2 = getSignature($file2);

Reload/restart the agent
After you've made the changes, restart your agent using the windows "services" control panel or "emctl reload agent" from the command line. Check the management console to make sure agent uploads have resumed properly, and then you should be ready to configure and test log file monitoring.
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Validating Oracle SSO Configuration

A failing OC4J_SECURITY process recently had me digging out an old script I had put together to test Oracle Application Server Single-Sign-On (OSSO) configuration.

How and where the OSSO server keeps its configuration is a wierd and wonderful thing. The first few times I faced OSSO server issues I remember digging through a collection of metalink notes to piece together the story. It was after forgetting the details a second time that I committed the understanding to a script (

Appreciating the indirection used in the configuration is the key to understanding how it all really hangs together, which can really help if you are trying to fix a server config issue. Things basically hang together in a chain with 3 links:

1. Firstly, the SSO server uses a privileged connection to an OID server to retrieve the OSSO (database) schema password.

2. With that password, it can retrieve the SSO OID (ldap) server connection details from the OSSO (database) schema.

3. Thus the SSO Server finally has the information needed to connect to the OID server that contains the user credentials.

The script I've provided here gives you a simple and non-destructive test of all these steps. The most common problem I've seen in practice is that the OSSO schema password stored in OID gets out of sync from the actual OSSO schema password. I think various causes of these problems, but the script will identity the exact point of failure in a jiffy.
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