Tuesday Dec 08, 2015

Monitoring FAN Events

fanWatcher is a sample program to print the Oracle Notification Service (ONS) Fast Application Notification (FAN) event information. These events provide information regarding load balancing, and service and instance up and down events. This information is automatically processed by WebLogic Server Active GridLink and UCP on the mid-tier. For more information about FAN events, see this link.  The program described here is an enhancement of the earlier program described in that white paper  This program can be modified to work as desired to monitor events and help diagnose problems with configuration. The code is available this link (rename it from .txt to .java).

To run this Java application, you need to be set up to run a JDK and you need ons.jar and ojdbcN.jar in the CLASSPATH. The CLASSPATH is set differently depending on whether you are running on the database server or on the mid-tier with WebLogic Server or UCP. Make sure to use the correct path separator for CLASSPATH on your platform (';' for Windows, ':' otherwise).

The general format for the command line is

java fanWatcher config_type [eventtype … ]

Event Type Subscription

The event type sets up the subscriber to only return limited events. You can run without specifying the event type to see what types of events are returned. When you specify an event name on the command line, the program sets up the subscriber to have a simple match on the event. If the specified pattern occurs anywhere in a notification's header, then the comparison statement evaluates true. The most basic pattern match is an empty string (not null), which matches all notifications. The pattern is enclosed in double quotes (required) and prefixed with “%” to be case insensitive.

Event processing is more complete than shown in this sample. The subscription string is generally composed of one or more comparison statements, each logically related to another with the boolean operators '|' for an OR relationship or '&' for an AND relationship. Parentheses are used to group these comparison statements, and the '!' operator placed before an opening parenthesis negates the evaluated value within.

Each individual comparison statement must be enclosed within double quotes ('"'), and can take one of two basic forms: "pattern" or "name=value". A "pattern" is a simple string match of the notification header: if the specified "pattern" occurs anywhere in a notification's header, then the comparison statement evaluates true. The most basic pattern match is an empty string (not NULL) which matches all notifications.

The "name=value" format compares the ONS notification header or property name with the name against the specified value, and if the values match, then the comparison statement evaluates true. If the specified header or property name does not exist in the notification the comparison statement evaluates false. A comparison statement will be interpreted as a case insensitive when a percent character ('%') is placed before the opening quote. Note that for "name=value" comparison statements, only the value is treated as case insensitive with this option: the name lookup will always be case sensitive. A comparison statement will be interpreted as a regular expression when a dollar sign character ('$') is placed before the opening quote. Standard POSIX regular expressions are supported. To specify a regular expression that is also case insensitive, place the dollar sign and percent sign together and in that order ("$%") before the opening quote.

A special case subscription string composed of only the exclamation point character ('!') signifies that the subscription will not match any notifications.

You might want to modify the event to select on a specific service by using something like

%"eventType=database/event/servicemetrics/<serviceName> "

Running with Database Server 10.2 or later

This approach runs on the database server and connects directly to the local ONS daemon available in the Grid Infrastructure cluster. The FANwatcher utility must be run as a user that has privilege to access the $CRS_HOME/opmn/conf/ons.config, which is used by the ons daemon to start and accessed by this program. The configuration type on the command line is set to “crs”.

# CRS_HOME should be set for your Grid infrastructure
echo $CRS_HOME
javac fanWatcher.java
java -Doracle.ons.oraclehome=$CRS_HOME fanWatcher crs

Running with WLS 10.3.6 or later using an explicit node list

There are two ways to run in a client environment – with an explicit node list and using auto-ONS. It’s necessary to have ojdbcN.jar and ons.jar that are available when configured for WLS. If you are set up to run with UCP directly, these should also be in your CLASSPATH.

In the first approach, it will work with Oracle driver and database 11 and later (SCAN support came in later versions of Oracle including the jar files that shipped with WLS 10.3.6).

# Set the WLS environment using wlserver*/server/bin/setWLSEnv
CLASSPATH="$CLASSPATH:." # add local directory for sample program
javac fanWatcher.java
java fanWatcher "nodes=rac1:6200,rac2:6200" database/event/service

The node list is a string of one or more values of the form name=value separated by a newline character (\n).

There are two supported formats for the node list.

The first format is available for all versions of ONS. The following names may be specified.

nodes – This is required. The format is one or more host:port pairs separated by a comma.

walletfile – Oracle wallet file used for SSL communication with the ONS server.

walletpassword – Password to open the Oracle wallet file.

The second format is available starting in database It supports more complicated topologies with multiple clusters and node lists. It has the following names.

nodes.id—this value is a list of nodes representing a unique topology of remote ONS servers. id specifies a unique identifier for the node list. Duplicate entries are ignored. The list of nodes configured in any list must not include any nodes configured in any other list for the same client or duplicate notifications will be sent and delivered. The list format is a comma separated list of ONS daemon listen addresses and ports pairs separated by colon.

maxconnections.id— this value specifies the maximum number of concurrent connections maintained with the ONS servers. id specifies the node list to which this parameter applies. The default is 3.

active.id If true, the list is active and connections are automatically established to the configured number of ONS servers. If false, the list is inactive and is only be used as a fail over list in the event that no connections for an active list can be established. An inactive list can only serve as a fail over for one active list at a time, and once a single connection is re-established on the active list, the fail-over list reverts to being inactive. Note that only notifications published by the client after a list has failed over are sent to the fail over list. id specifies the node list to which this parameter applies. The default is true.

remotetimeout —The timeout period, in milliseconds, for a connection to each remote server. If the remote server has not responded within this timeout period, the connection is closed. The default is 30 seconds.

The walletfile and walletpassword may also be specified (note that there is one walletfile for all ONS servers). The nodes attribute cannot be combined with name.id attributes.

Running with WLS using auto-ONS

Auto-ONS is available starting in Database Before that, no information is available. Auto-ONS only works with RAC configurations; it does not work with an Oracle Restart environment.  Since the first version of WLS that ships with Database 12.1 is WLS 12.1.3, this approach will only work with upgraded database jar files on versions of WLS earlier than 12.1.3. Auto-ONS works by getting a connection to the database to query the ONS information from the server. For this program to work, a user, password, and URL are required. For the sample program, the values are assumed to be in the environment (to avoid putting them on the command line). If you want, you can change the program to prompt for them or hard-code the values into the java code.

# Set the WLS environment using wlserver*/server/bin/setWLSEnv
# Set the credentials in the environment. If you don't like doing this,
# hard-code them into the java program
export password url user
javac fanWatcher.java
java fanWatcher autoons

fanWatcher Output

The output looks like the following. You can modify the program to change the output as desired. In this short output capture, there is a metric event and an event caused by stopping the service on one of the instances.

** Event Header **
Notification Type: database/event/servicemetrics/otrade
Delivery Time: Fri Dec 04 20:08:10 EST 2015
Creation Time: Fri Dec 04 20:08:10 EST 2015
Generating Node: rac1
Event payload:
VERSION=1.0 database=dev service=otrade { {instance=inst2 percent=50 flag=U
NKNOWN aff=FALSE}{instance=inst1 percent=50 flag=UNKNOWN aff=FALSE} } timestam
p=2015-12-04 17:08:03

** Event Header **
Notification Type: database/event/service
Delivery Time: Fri Dec 04 20:08:20 EST 2015
Creation Time: Fri Dec 04 20:08:20 EST 2015
Generating Node: rac1
Event payload:
VERSION=1.0 event_type=SERVICEMEMBER service=otrade instance=inst2 database=dev db_domain= host=rac2 status=down reason=USER timestamp=2015-12-04 17:

Monday Jun 30, 2014

Oracle WebLogic Server 12.1.3 Whitepaper - Developing with WebLogic Server

One of the most significant areas of investment in WebLogic Server 12.1.3 has been in developer productivity and API updates, as I summarized in my blog from last week.   However, a brief summary is typically not enough for developers who want a more detailed description of the improvements we have delivered.   And although product documentation contains all of the relevant updates, sometime it does not capture the overall background on the topic that puts the improvements into context.  

Steve Button from the WebLogic Server product management team has published an excellent whitepaper on OTN - Oracle WebLogic Server 12.1.3 Whitepaper - Developing with WebLogic Server - which provides a detailed description of the new features, along with the background which explains why we delivered the improvements, and the benefits they offer.   The whitepaper covers new WebLogic Server 12.1.3 features in the areas of WebSocket, JSON, JAX-RS, JPA, Server-Sent Events, Maven and more.

If you are a WebLogic Server user looking for a detailed description of the latest development features in WebLogic Server 12.1.3, and how you can leverage them in your applications, this is an excellent resource.   Please take a look!


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