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Weblogic Tutorials And Interview Questions For Beginners

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WebLogic Interview Questions

weblogic-interview-questions-and-answers

Oracle WebLogic Interview Questions

interview-questions-on-oracle-weblogic

&nbsp;
<h2 style="text-align: justify;">WebLogic Interview Questions and Answers</h2>
<h3 style="text-align: justify;">Q1) How do you differentiate between a server hang and server crash issue?</h3>
Ans: 
<ul>
<li style="text-align: justify;">When a server crashes, the JAVA process no longer exists. When the server is hung, it stops responding.</li>
<li style="text-align: justify;">We can use the Weblogic.ADMIN utility to ping the server. In case of a hang situation, we can take multiple thread dumps and analyze the cause of the hang.</li>
</ul>
<h3 style="text-align: justify;">Q2) What can be the various reasons for a server crash?</h3>
Ans:
<ul style="text-align: justify;">
<li style="text-align: justify;">Native IO</li>
<li style="text-align: justify;">SSL Native Libraries</li>
<li style="text-align: justify;">JVM</li>
<li style="text-align: justify;">Supported Configuration</li>
<li style="text-align: justify;">JDBC Driver issue</li>
</ul>
<h3 style="text-align: justify;">Q3) How do you troubleshoot a crash?</h3>
Ans:
<ul style="text-align: justify;">
<li style="text-align: justify; padding-left: 30px;">JVM crash generates a hs_err_pid file. We need to look into the stack trace of the hs_err_pid file.</li>
<li style="text-align: justify; padding-left: 30px;">If the thread is from a native<a href="https://en.wikipedia.org/wiki/Input/output" target="_blank" rel="noopener"> i/o</a>, we need to disable native io.</li>
<li style="text-align: justify; padding-left: 30px;">if the stack trace is from the driver, we need to get in touch with the drive team.</li>
<li style="text-align: justify; padding-left: 30px;">Quite possibly its a problem with the driver. Changing the type of driver can be a workaround.</li>
<li style="text-align: justify; padding-left: 30px;">If the thread shows it coming from an optimized code, we can turn off optimization.</li>
<li style="text-align: justify; padding-left: 30px;"> If the stack is from native calls of application, its a bug with the application and it has to b modified.</li>
</ul>
<h3 style="text-align: justify;">Q4) How do you troubleshoot Server Hang?</h3>
Ans: We can use java Weblogic. Admin PING to check if we get a normal response. We need to take multiple thread dumps with kill -3 paid on unix and CTLR Break on Windows. Analyze the thread dump to find the root cause.
<h3 style="text-align: justify;">Q5) What can be the reasons for the Server hang?</h3>
Ans: Memory leak, database query taking a long time to return, Deadlock.
<h3 style="text-align: justify;">Q6) What is a memory leak?</h3>
Ans: A memory leak is when objects are not removed from the heap even when they are not required.
<h3 style="text-align: justify;">Q7) What are the various causes for OUT OF MEMORY?</h3>
Ans:
<ul style="text-align: justify;">
<li>Insufficient heap size, not able to match the extra load.</li>
<li>Objects lying too long, like HTTP Sessions.</li>
<li>Memory leak in application code.</li>
<li>Full GC not happening due to JVM Bug.</li>
</ul>
<blockquote>
Inclined to build a profession as Weblogic Developer? Then here is the blog post on, explore <a title="Weblogic Training" href="weblogic-server-administration-training" target="_blank" rel="noopener">Weblogic Training</a>
</blockquote>
<h3 style="text-align: justify;">Q8) How to troubleshoot and overcome such issues?</h3>
Ans:
<ul style="text-align: justify;">
<li style="text-align: justify; padding-left: 30px;">Gather memory data by enabling GC verbose.</li>
<li style="text-align: justify; padding-left: 30px;">If its due to Http Session, timing out http session after a certain interval might help.</li>
<li style="text-align: justify; padding-left: 30px;">Look into the code for JDBC connection handling.</li>
<li style="text-align: justify; padding-left: 30px;">Optimizing the heap size according to the load.</li>
</ul>
<h3 style="text-align: justify;">Q9) When does High CPU Usage occur?</h3>
Ans: It occurs when one process or one thread utilizes an unexpectedly high proportion of CPU.
<h3 style="text-align: justify;">Q10) How to troubleshoot it?</h3>
Ans: In the Solaris environment, we need to take pstack and prstack and see what the threads are doing. In Windows, we need to use pslist and process explorer.
<h3 style="text-align: justify;">Q11) What is Clustering and what is achieved through it?</h3>
Ans: 
<ul>
<li style="text-align: justify;">Clustering is the grouping together of servers for the purpose of high availability and scalability.</li>
<li style="text-align: justify;">Load balancing and Failover is achieved.</li>
</ul>
<h3 style="text-align: justify;">Q12) How does Cluster Communication Happen?</h3>
Ans: Members of the Cluster communicate over the Cluster Multicast IP and Port by sending periodic heartbeat messages.
<h3 style="text-align: justify;">Q13) What is the difference between the Sun JVM and BEA JRockit JVM?</h3>
Ans:
<ul>
<li style="text-align: justify;">The most well know JVM is the implementation from Sun. The Sun JVM is called HotSpot. The Sun JVM is shipped in the Java Developer&rsquo;s Kit (JDK) and Java Runtime Environment (JRE) from Sun.</li>
<li style="text-align: justify;">The BEA JRockit JVM from BEA systems is optimized for reliability and performance for server-side applications. To achieve this, BEA JRockit JVM uses technologies such as code generation, hot spot detection, code optimization, advanced garbage collection algorithms, and tight operating system integration.</li>
</ul>
Tuning JVM Parameters:
If you have a single processor, a single-thread machine then you should use the serial collector (default for some configurations, can be enabled explicitly for with -XX:+UseSerialGC). For multiprocessor machines where your workload is basically CPU bound, use the parallel collector. This is enabled by default if you use the -server flag, or you can enable it explicitly with -XX:+UseParallelGC. If you&rsquo;d rather keep the GC pauses shorter at the expense of using more total CPU time for GC, and you have more than one CPU, you can use the concurrent collector (-XX:+UseConcMarkSweepGC). Note that the concurrent collector tends to require more RAM allocated to the JVM than the serial or parallel collectors for a given workload because some memory fragmentation can occur.
<h3 style="text-align: justify;">Q14) How do you do performance tuning of WLS?</h3>
Ans: It can be categorized into 4 parts. a. Application Tuning. jsp precompilation, ejb pool size cache..
<ul style="text-align: justify;">
<li>OS Tuning</li>
</ul>
Setting the TCP IP parameter. tcp_time_wait_interval tcp_conn_req_max_q
<ul style="text-align: justify;">
<li>Core Server Tuning.</li>
</ul>
tune work manager, tune chuck size and chunk pool size, using performance packs, connection backlog buffering.
<ul style="text-align: justify;">
<li>JVM Tuning</li>
</ul>
tuning gc strategy, monitoring garbage collection.
<h3 style="text-align: justify;">Q15) What is the difference between the Development mode and Production mode of the Weblogic Server?</h3>
Ans: 
Development Mode:
<ul style="text-align: justify;">
<li>The default JDK for the development domain is Sun Hotspot.</li>
<li>&nbsp;You can use the demo certificates for SSL.</li>
<li>Auto deployment(to admin server only) is enabled.</li>
<li>&nbsp;Server instances rotate their log files on start-up.</li>
<li>Admin Server uses an automatically created boot.properties during start-up.</li>
<li>The default maximum capacity for JDBC Datasource is 15.</li>
<li>The debug flag which is used to start the WebLogic Workshop Debugger is enabled.</li>
<li>In Development Mode any configuration change is done by a user who doesn&rsquo;t need him to take a Lock and Edit session.</li>
<li>Availability of web service test client.</li>
<li>Node manager username and password: Default Admin credentials.</li>
<li>Availability of Classloader Analysis Tool: Yes.</li>
<li>Default start parameters when using Sun JDK and the default startWebLogic script : java -client -Xms256m -Xmx512m -XX:CompileThreshold=8000 -XX:PermSize=128m -XX:MaxPermSize=256m.</li>
</ul>
Production Mode:
<ul style="text-align: justify;">
<li>The default JDK for the production domain is JRockit.</li>
<li>If you use the demo certificates for SSL a warning is displayed.</li>
<li>Auto deployment(to admin server only) is disabled.</li>
<li>Server instances rotate their log files when it reaches 5MB.</li>
<li>Admin Server prompts for username and password during start-up.</li>
<li>The default maximum capacity for JDBC Datasource is 25.</li>
<li>The debug flag which is used to start the WebLogic Workshop Debugger is disabled.</li>
<li>In Production Mode the user needs to procure a Lock and Edit session before trying to make any configurational changes.</li>
<li>No Availability of web service test client.</li>
<li>Node manager username and password: Randomly generated</li>
<li>Availability of Classloader Analysis Tool: No.</li>
<li>Default start parameters when using Sun JDK and the default startWebLogic script : java -server -Xms256m -Xmx512m -XX:MaxPermSize=256m.</li>
</ul>
<h3 style="text-align: justify;">Q16) What is HTTP tunneling? How can we configure it on Weblogic?</h3>
Ans: 
<ul>
<li style="text-align: justify;">HTTP tunneling provides a way to simulate a stateful socket connection between WebLogic Server and a Java client when your only option is to use the HTTP protocol. It is generally used to tunnel through an HTTP port in a security firewall. HTTP is a stateless protocol, but WebLogic Server provides tunneling functionality to make the connection appear to be a regular T3Connection. Steps to configure Http tunneling.</li>
<li style="text-align: justify;">Login into the Admin Console, click on the server on which you want to enable the Http Tunneling feature Click on the Protocols tab? General? check the &ldquo;Enable Tunneling&rdquo; checkbox.</li>
<li style="text-align: justify;">Now you can communicate with the JVMs (Server Instances) using protocols other than t3</li>
</ul>
<h3 style="text-align: justify;">Q17) What is the difference between T3 and HTTP protocol?</h3>
Ans: 
<ul>
<li style="text-align: justify;">WebLogic uses the T3 protocols for internal and external connections to the servers. The T3 protocol often is used in WebLogic&rsquo;s implementation of RMI. Proprietary of <a href="https://tekslate.com/weblogic-server-installation/" target="_blank" rel="noopener">WebLogic Server</a>.</li>
<li style="text-align: justify;">Http protocols are used primarily for HTTP communication between the browser and the webserver. Standard follows the W3C (World Wide Web Consortium).</li>
</ul>
Note: All of these protocols are, by default, multiplexed over the same connection to the server&rsquo;s address and port. So you can access a web page hosted by the server using a URL such as http://host:port/page.jsp. An external client can set up an initial JNDI context to a server using the URL t3://host: port/. All that has changed is the protocol over which the client must communicate with the server.
<a style="background-color: #e94350; color: #ffffff; padding: 10px 20px;" title="Weblogic Interview Questions and Tutorials" href="tutorialsweblogic-tutorials-how-to" target="_blank" rel="noopener">Weblogic Interview Questions and Tutorials</a>

interview-questions-on-weblogic

&nbsp;
<h2>Replicating session in JBoss&nbsp;</h2>
In this tutorial, we will see how to do&nbsp;Session replication in Weblogic Cluster You now need to use the&nbsp;node1&nbsp;and&nbsp;node2&nbsp;created before In&nbsp;session-test.war/WEB-INF/web.xml, add:
&nbsp; &lt;web-app&gt;
&nbsp; &lt;display-name&gt;Session Test&lt;/display-name&gt;
&nbsp; &lt;description&gt;...&lt;/description&gt;
&nbsp; &lt;distributable/&gt; &lt;!-- &nbsp;--&gt;
&nbsp; ...
&lt;/web-app&gt;
<table style="width: 690px;" width="690">
<tbody>
<tr>
<td style="width: 675.219px;">Your application&rsquo;s HTTP sessions now use the distributed cache.</td>
</tr>
</tbody>
</table>
Now:
<ul>
<li>Disable sticky sessions (optional)</li>
<li>Redeploy session-test.war to node1/deploy and node2/deploy directories</li>
<li>Restart and retest You can now see that your application is fault-tolerant, it supports failover AND state replication Problems with sticky sessions?</li>
<li>Uneven distribution of load</li>
<li>If one instance goes down, all of its sessions go with it</li>
</ul>
You can configure session replication here:
<ul>
<li>Sessions are replicated by&nbsp;all/deploy/cluster/jboss-cache-manager.sar:</li>
<li>Cache Mode:&nbsp;REPL_SYNC,&nbsp;REPL_ASYNC</li>
<li>Caching Configuration: replication queue</li>
<li>Cluster Name and Configuration: communication</li>
</ul>
<blockquote>
Inclined to build a profession as JBoss Developer? Then here is the blog post on, explore <a title="JBoss Training" href="jboss-training" target="_blank" rel="noopener">JBoss Training</a>
</blockquote>
<ul>
<li>Configure session replication per app in WEB-INF/jboss-web.xml</li>
</ul>
Replication trigger:&nbsp;SET,&nbsp;SET_AND_GET,&nbsp;SET_AND_NON_PRIMITIVE_GET,&nbsp;ACCESS
Replication granularity:&nbsp;SESSION,&nbsp;ATTRIBUTE,&nbsp;FIELD
deploy/cluster/jboss-cache-manager.sar/META-INF/jboss-cache-manager-jboss-beans.xml:
&lt;deployment ...&gt;
&nbsp; ...
&nbsp;&lt;bean name="CacheConfigurationRegistry" ...&gt;
&nbsp; ...
&nbsp;&lt;property name="newConfigurations"&gt;
&nbsp; &lt;map keyClass="java.lang.String" valueClass="org.jboss.cache.config.Configuration"&gt;
&nbsp; &lt;entry&gt;&lt;key&gt;standard-session-cache&lt;/key&gt;
&nbsp; &nbsp;&lt;value&gt;
&nbsp; &nbsp;&lt;bean name="StandardSessionCacheConfig" class="org.jboss.cache.config.Configuration"&gt;
&nbsp; &nbsp; ...
&nbsp; &nbsp;&lt;property name="clusterName"&gt;${jboss.partition.name:DefaultPartition}-SessionCache&lt;/property&gt;
&nbsp; &nbsp; &lt;property name="multiplexerStack"&gt;${jboss.default.jgroups.stack:udp}&lt;/property&gt;
&nbsp; &nbsp; &lt;property name="fetchInMemoryState"&gt;true&lt;/property&gt;
&nbsp; &nbsp; &lt;property name="nodeLockingScheme"&gt;PESSIMISTIC&lt;/property&gt;
&nbsp; &nbsp; &lt;property name="isolationLevel"&gt;REPEATABLE_READ&lt;/property&gt;
&nbsp; &nbsp; &nbsp;&lt;property name="useLockStriping"&gt;false&lt;/property&gt;
&nbsp; &nbsp; &nbsp;&lt;property name="cacheMode"&gt;REPL_ASYNC&lt;/property&gt;
&nbsp; &nbsp; &nbsp;&lt;property name="syncReplTimeout"&gt;17500&lt;/property&gt;
&nbsp; &nbsp; &nbsp;&lt;property name="lockAcquisitionTimeout"&gt;15000&lt;/property&gt;
&nbsp; &nbsp; &nbsp; &nbsp;...
&nbsp; &nbsp; &nbsp;&lt;/bean&gt;
&nbsp; &nbsp; &nbsp;&lt;/value&gt;
&nbsp;&nbsp;&nbsp;&nbsp; &lt;/entry&gt;
&nbsp;&nbsp;&nbsp;&nbsp; ...
&nbsp; &nbsp; &lt;/map&gt;
&nbsp; &nbsp; &lt;/property&gt;
&nbsp; &nbsp; ...
&nbsp; &nbsp;&lt;/bean&gt;
&nbsp; &nbsp;...
&nbsp; &nbsp;&lt;/deployment&gt;
You can also specify for each application some parameters: WEB-INF/jboss-web.xml:
&lt;jboss-web&gt;
&nbsp;&lt;replication-config&gt;
&nbsp;&lt;replication-trigger&gt;SET_AND_NON_PRIMITIVE_GET&lt;/replication-trigger&gt;
&nbsp;&lt;replication-granularity&gt;SESSION&lt;/replication-granularity&gt;
&nbsp;&lt;/replication-config&gt;
&nbsp;&lt;/jboss-web&gt;
<h2>For indepth understanding on JBoss click on:</h2>
<ul>
<li><a href="http://tekslate.com/jboss-architecture/" target="_blank" rel="noopener">JBoss architecture</a></li>
<li><a href="http://tekslate.com/how-to-install-jboss-application-server/" target="_blank" rel="noopener">Installation of jboss</a></li>
<li><a href="reactjs-training/" target="_blank" rel="noopener">Advanced Java Training in Houston</a></li>
<li><a href="http://tekslate.com/session-configuration-in-jboss/" target="_blank" rel="noopener">Session Configuration</a></li>
<li><a href="http://tekslate.com/tutorials/jboss/" target="_blank" rel="noopener">JBoss&nbsp;Tutorials</a></li>
<li><a href="http://tekslate.com/tutorials/jboss/" target="_blank" rel="noopener">JBoss Overview</a></li>
</ul>

Session Replication in Weblogic Cluster

Session replication in Weblogic Cluster

session-replication-in-weblogic-cluster

&nbsp;
WebLogic Server is based on Java 2 Platform, Enterprise Edition (J2EE), the standard platform used to create Java-based multi-tier enterprise applications. J2EE platform technologies were developed through the efforts of BEA Systems and other vendors in collaboration with the main developer, Sun Microsystems.&nbsp;It manages system-level details so you can concentrate on business logic and presentation.
The following are the various Weblogic Server&nbsp;versions released from 2002. The most recent version of Weblogic is 12c.
<h2 style="text-align: justify;">Weblogic Server Versions</h2>
WebLogic Server 12c Release 3 (12.1.3) - June 26, 2014
WebLogic Server 12c Release 2 (12.1.2) - July 11, 2013
WebLogic Server 12c Release 1 (12.1.1) - Dec 1, 2011
WebLogic Server 11gR1 PS5 (10.3.6) - February 26, 2012
WebLogic Server 11gR1 PS4 (10.3.5) - May 16, 2011
WebLogic Server 11gR1 PS3 (10.3.4) - January 15, 2011
WebLogic Server 11gR1 PS2 (10.3.3) - April 2010
WebLogic Server 11gR1 PS1 (10.3.2) - Nov 2009
WebLogic Server 11g (10.3.1) - Jul 2009
WebLogic Server 10.3 - Aug 2008
WebLogic Server 10.0 - Mar 2007
WebLogic Server 9.2
WebLogic Server 9.1
WebLogic Server 9.0 - Nov 2006
WebLogic Server 8.1 - Jul 2003
WebLogic Server 7.0 - Jun 2002
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<h2 style="text-align: justify;">Weblogic Server Core Components</h2>
Oracle WebLogic Server supports Oracle, DB2, MS SQL Server, MySQL Enterprise and other JDBC-compliant databases. Oracle Weblogic Platform also includes:
<ul style="text-align: justify;">
<li>Core Components like Enterprise Grid Messaging, JMS Messaging Standard, JRockit, Oracle Top Link, Oracle WebLogic Server Web Services, Tuxedo</li>
</ul>
<ul style="text-align: justify;">
<li>Supported open standards like <a href="http://tekslate.com/administering-bpel-process-service-components-engines/" target="_blank" rel="noopener">BPEL</a> &amp; BPEL-J, ebXML, JAAS, Java EE 1.3 &amp; 1.4 &amp; 5, JPA 1.0 (2.0 available), JMX and SNMP</li>
</ul>
<ul style="text-align: justify;">
<li>Native support for: SOAP, UDDI, WSDL, WSRP, WS-Security, XSLT and XQuery</li>
</ul>
<h3 style="text-align: justify;">Standards support by version</h3>
The table below lists major standards supported by the WebLogic Server product version.
<table>
<tbody>
<tr>
<td>Standard</td>
<td>WLS 7.0</td>
<td>WLS 8.1</td>
<td>WLS 9.0</td>
<td>WLS 10.0</td>
<td>WLS 10.3</td>
</tr>
<tr>
<td>Java</td>
<td>1.3</td>
<td>1.4</td>
<td>5</td>
<td>5</td>
<td>6</td>
</tr>
<tr>
<td>Java EE</td>
<td>1.3</td>
<td>1.3</td>
<td>1.4</td>
<td>5</td>
<td>5</td>
</tr>
</tbody>
</table>
<h2 style="text-align: justify;">Overview of WebLogic Server System Administration</h2>
System administration of WebLogic Server includes a wide range of tasks: creating WebLogic Server domains; deploying applications; migrating domains from development environments to production environments; monitoring and managing the performance of the run-time system, and diagnosing and troubleshooting problems. (A WebLogic Server domain is a collection of WebLogic Server services designed for a specific purpose. For example, you might create one domain to provide an employee portal and another domain to provide business services to your customers.)
Because the WebLogic Server management system is based on Java EE and other standards, it integrates with systems that are frequently used to manage other software and hardware components. Also, WebLogic Server includes several of its own standards-based, extensible utilities. Alternatively, you can use APIs to create custom management utilities.
At the end of this module you will be able to:
<ul style="text-align: justify;">
<li>What are Software Component Tiers</li>
<li>The Web &amp; Application Server and Differences</li>
<li>J2EE Platform and WebLogic Server</li>
<li>Weblogic Server Versions &amp; Capabilities</li>
</ul>
<h2 style="text-align: justify;">Software Component Tiers</h2>
The software components of a multitier architecture consist of three tiers:
<ul style="text-align: justify;">
<li>The client tier contains programs executed by users, including Web browsers and network-capable application programs. These programs can be written in virtually any programming language.</li>
</ul>
<ul style="text-align: justify;">
<li>The middle tier contains <a href="http://tekslate.com/configuring-weblogic-server-environment/" target="_blank" rel="noopener">WebLogic Server</a> and other servers that are addressed directly by clients, such as existing Web servers or proxy servers.</li>
</ul>
<ul style="text-align: justify;">
<li>The backend tier contains enterprise resources, such as database systems, mainframe and legacy applications, and packaged enterprise resource planning (ERP) applications.</li>
</ul>
<img class="aligncenter wp-image-2254" title="Weblogic Server Component Tiers" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/126.png" alt="Weblogic Server Component Tiers" width="352" height="306" />
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<h2 style="text-align: justify;">The Web Server</h2>
A Web server handles the HTTP protocol. When the Web server receives an HTTP request, it responds with an HTTP response, such as sending back an <a href="http://tekslate.com/tutorials/html-tutorials/" target="_blank" rel="noopener">HTML</a> page. To process a request, a Web server may respond with a static HTML page or image, send a redirect, or delegate the dynamic response generation to some other program such as CGI scripts, JSPs (JavaServer Pages), servlets, ASPs (Active Server Pages), server-side JavaScripts, or some other server-side technology. Whatever their purpose, such server-side programs generate a response, most often in HTML, for viewing in a Web browser.
Understand that a Web server's delegation model is fairly simple. When a request comes into the Web server, the Web server simply passes the request to the program best able to handle it. The Web server doesn't provide any functionality beyond simply providing an environment in which the server-side program can execute and pass back the generated responses. The server-side program usually provides for itself such functions as transaction processing, database connectivity, and messaging.
While a Web server may not itself support transactions or database connection pooling, it may employ various strategies for fault tolerance and scalability such as load balancing, caching, and clustering&mdash;features often erroneously assigned as features reserved only for application servers.
<ul style="text-align: justify;">
<li>Provides Web content</li>
<li>Communicate via HTTP, FTP, etc</li>
<li>Can handle CGI requests</li>
</ul>
Proxy some requests to Application Servers
<img class="wp-image-2255 aligncenter" title="Weblogic Server" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/217.png" alt="Weblogic Server" width="508" height="272" />
<h2 style="text-align: justify;">The Application Server</h2>
&nbsp;As for the application server, according to our definition, an application server exposes business logic to client applications through various protocols, possibly including HTTP. While a Web server mainly deals with sending HTML for display in a Web browser, an application server provides access to business logic for use by client application programs. The application program can use this logic just as it would call a method on an object (or a function in the procedural world).
Such application server clients can include GUIs (graphical user interface) running on a PC, a Web server, or even other application servers. The information traveling back and forth between an application server and its client is not restricted to simple display markup. Instead, the information is program logic. Since the logic takes the form of data and method calls and not static HTML, the client can employ the exposed business logic however it wants.
In most cases, the server exposes this business logic through a component API, such as the EJB (Enterprise JavaBean) component model found on J2EE (Java 2 Platform, Enterprise Edition) application servers. Moreover, the application server manages its own resources. Such gate-keeping duties include security, transaction processing, resource pooling, and messaging. As&nbsp;a Web server, an application server may also employ various scalability and fault-tolerance techniques.
<img class="wp-image-2256 aligncenter" title="Weblogic Application Server" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/317.png" alt="Weblogic Application Server" width="388" height="313" />
<h4 style="text-align: justify;">Application servers:</h4>
<ul style="text-align: justify;">
<li>Provide services that support the execution and availability of deployed applications</li>
<li>Handle heavier processing chores than Web servers</li>
</ul>
<h3 style="text-align: justify;">Differences Between Application Server vs. Web Server</h3>
<h4 style="text-align: justify;">&nbsp;What is it?</h4>
Application Server: A server that exposes business logic to client applications through various protocols including HTTP.
Web Server: A server that handles HTTP protocol.
<h4 style="text-align: justify;">Functions:</h4>
Application Server: To deliver various applications to another device, it allows everyone in the network to run software off of the same machine.
Web Server: Keeping HTML, PHP, ASP, etc. files available for the web browsers to view when a user accesses the site on the web, handles HTTP requests from clients.
<h4 style="text-align: justify;">Clients can include:</h4>
Application Server:&nbsp; GUI&rsquo;s, Web Servers
Web Server: &nbsp;HTTP, HTML
<h4 style="text-align: justify;">Functionality:</h4>
Application Server:&nbsp; Adds functionality
Web Server: Does not add any
<h4 style="text-align: justify;">Examples of popular server products:</h4>
Application Server:&nbsp; Oracle OC4J(Oracle), Sybase Application server(Sybase), SAP Netweaver (SAP), <a title="JBoss" href="jboss" target="_blank" rel="noopener">Jboss</a> (Red Hat), WebLogic Server (Oracle), WebSphere (IBM)
Web Server: &nbsp;Microsoft IIS, Apache Tomcat
<h2 style="text-align: justify;">&nbsp;J2EE Platform and WebLogic Server</h2>
&nbsp;WebLogic Server J2EE applications are based on standardized, modular components. WebLogic Server provides a complete set of services for those modules and handles many details of application behavior automatically, without requiring programming.
J2EE includes deployment specifications for Web applications, EJB modules, Enterprise applications, client applications, and connectors. J2EE does not specify how an application is deployed on the target server&mdash;only how a standard module or application is packaged.
Java is platform independent, so you can edit and compile code on any platform, and test your applications on development WebLogic Servers running on other platforms. For example, it is common to develop WebLogic Server applications on a PC running Windows or Linux, regardless of the platform where the application is ultimately deployed.
<h4 style="text-align: justify;">Summary:&nbsp;</h4>
<ul style="text-align: justify;">
<li>Covered Software Component Tiers</li>
<li>Covered Overview and Differences of Web Server and Application Server</li>
<li>Overview of J2EE Platform and WebLogic Server</li>
</ul>
<h2>For indepth understanding of Weblogic click on </h2>
<ul>
<li><a title="Weblogic Tutorials" href="tutorialsweblogic-tutorials-how-to" target="_blank" rel="noopener">Weblogic Tutorials</a></li>
<li class="title"><a class="current-page" title="WebLogic Server Installation" href="http://tekslate.com/weblogic-server-installation/" target="_blank" rel="noopener">WebLogic Server Installation</a></li>
<li class="title"><a class="current-page" title="Terminology and WLS Architecture" href="http://tekslate.com/terminology-wls-architecture/" target="_blank" rel="noopener">Terminology &amp; WLS Architecture</a></li>
<li class="title"><a class="current-page" title="Managing Server Startup and Shutdown" href="http://tekslate.com/managing-server-startup-shutdown/" target="_blank" rel="noopener">Managing Server Startup and Shutdown</a></li>
<li class="title"><a class="current-page" title="Weblogic Node Manager Overview" href="http://tekslate.com/node-manager-overview-weblogic/" target="_blank" rel="noopener">Weblogic Node Manager Overview</a></li>
</ul>
&nbsp;
Our course design of tutorials is practical and informative. At TekSlate, we offer resources to help you learn various IT courses. We avail of both written material and demo video tutorials. For in-depth knowledge and practical experience explore <a href="http://tekslate.com/weblogic-server-administration-training/" target="_blank" rel="noopener">Online WebLogic Training</a>.

Weblogic Server | What is Weblogic Application Server

Overview of Weblogic Application Server

overview-weblogic-application-server

WebLogic Server Installation

weblogic-server-installation

Weblogic Server Environment

Configuring a WebLogic Server Environment

configuring-weblogic-server-environment

&nbsp;
At the end of this chapter you will be able to:
<ul>
<li>Overview of the Node Manager</li>
<li>Versions of Node Manager</li>
<li>Accessing Node Manager</li>
<li>How Node Manager Works in the WebLogic Server Environment</li>
<li>Node Manager Configuration &amp; Log Files</li>
</ul>
<h2>Overview: </h2>
<ul>
<li>Server instances in a WebLogic Server production environment are often distributed across multiple domains, machines, and geographic locations. Node Manager is a WebLogic Server utility that enables you to start, shut down, and restart Administration Server and Managed Server instances from a remote location. Although Node Manager is optional, it is recommended if your WebLogic Server environment hosts applications with high availability requirements.</li>
<li>A Node Manager process is not associated with a specific WebLogic domain but with a machine. You can use the same Node Manager process to control server instances in any WebLogic Server domain, as long as the server instances reside on the same machine as the Node Manager process. &nbsp;</li>
</ul>
<h2>Node Manager (NM):</h2>
<ul>
<li>Lets you start and kill managed servers remotely: one server, a domain, a cluster</li>
<li>Is available as either a Java-based or (for UNIX or Linux) a script-based process.</li>
<li>Monitors and acts on server health</li>
<li>Runs on the same computers as the managed servers</li>
<li>Can be run automatically in the background, as a Windows service or a Unix daemon</li>
</ul>
<h3>What Node Manager Can Do </h3>
Node Manager can be used to:
<ul>
<li>Start, Shut Down, and Restart an Administration Server.</li>
<li>Start, Shut Down, Suspend, and Restart Managed Servers.</li>
<li>Automatically Restart Administration and Managed Servers on failure.</li>
<li>Monitor Servers and collects log data.</li>
</ul>
<h2>Node Manager Versions </h2>
WebLogic Server provides two versions of Node Manager, Java-based and script-based, with similar functionality. However, each version has a different configuration and security considerations. &nbsp;
<h2>Java-based Node Manager </h2>
<ul>
<li>Java-based Node Manager runs within a Java Virtual Machine (JVM) process. It is recommended that you run it as a Windows service on Windows platforms and as an operating system service on UNIX platforms, allowing it to restart automatically when the system is rebooted.</li>
<li>This version of the Node Manager determines its configuration from the node manager.properties file. Java-based Node Manager provides more security than the script-based version. &nbsp;</li>
</ul>
<h2>Script-based Node Manager </h2>
<ul>
<li>For UNIX and Linux systems, WebLogic Server provides a script-based version of Node Manager. This script is based on UNIX shell scripts but uses SSH for increased security. SSH uses user-id based security.</li>
<li>This version does not provide as much security as the Java-based version. However, the advantage of the script-based Node Manager is that it can remotely manage servers over a network that has been configured to use SSH. No additional server installation is required. The scripts merely have to be copied to the remote machine.</li>
</ul>
 Note:
It is recommended that you run a script-based Node Manager as an operating system service, which allows it to restart automatically when the system is rebooted. &nbsp;
<h3> Determining Which Node Manager Version to Use </h3>
Which version of Node Manager to use depends on the requirements of your WebLogic Server environment. The following considerations can help you decide which version is ideal for your environment:
<ul>
<li>If you are installing WebLogic Server on a Windows system, you must use the Java version of Node Manager. The scripted version of the Node Manager is not supported on Windows.</li>
</ul>
<ul>
<li>In order to use db-less leasing (consensus leasing), you may see faster performance when using the Java version of Node Manager.</li>
</ul>
<ul>
<li>The script-based Node Manager requires a much simpler security configuration than the Java version. RSH and SSH are generally easier to configure than SSL which is the security method used by the Java version of Node Manager. The script version of the Node Manager also requires a smaller footprint than the Java version.</li>
</ul>
<ul>
<li>The Java version of Node Manager can be used in conjunction with inetd on supported UNIX systems. inetd allows Node Manager to be automatically restarted upon receiving requests on the configured port.</li>
</ul>
<h2>Accessing Node Manager </h2>
A Node Manager client can be local or remote to the Node Managers with which it communicates. You access either version of Node Manager&mdash;the Java version or the script-based (SSH) version&mdash;from the following clients: &nbsp;
<h3>Administration Server</h3>
<ul>
<li>Administration Console, from the Environments&rarr;Machines&rarr;Configuration&rarr;Node Manager page.</li>
</ul>
<h3>WLST commands and scripts </h3>
WLST offline serves as a Node Manager command-line interface that can run in the absence of a running Administration Server. You can use WLST commands to start, stop, and monitor a server instance without connecting to an Administration Server. Starting the Administration Server is the main purpose of the stand-alone client. However, you can also use WLST to:
<ul>
<li>Stop a server instance that was started by Node Manager.</li>
<li>Start a Managed Server.</li>
<li>Access the contents of a Node Manager log file.</li>
<li>Obtain server status for a server that was started with Node Manager.</li>
<li>Retrieve the contents of the server output log.</li>
</ul>
<h2>How Node Manager Works in the WebLogic Server Environment &nbsp; </h2>
<h3>Node Manager Architecture: </h3>
The following diagram specifies the relationship between Node Manager, its clients, and the server instances it controls.
<img class="alignnone wp-image-2422" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/854-460x289.png" alt="Node manager architecture" width="469" height="294" />
<h3>How Node Manager Starts an Administration Server</h3>
<img class="alignnone wp-image-2423" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/863-460x254.png" alt="Node manager" width="442" height="243" />
<ol>
<li>An authorized user issues the WLST offline command, nmConnect to connect to the Node Manager process on the machine that hosts the Administration Server, and issues a command to start the Administration Server. The start command identifies the domain and server instance to start, and in the case of the Java Node Manager, provides the Node Manager username and password.</li>
</ol>
Note: If the user has previously connected to the Node Manager, a boot.properties file exists, and the user does not have to supply a username and password.
2 &amp; 3. Node Manager looks up the domain directory in nodemanager.domains and authenticates the user credentials using a local file that contains the encrypted username and password.
<ul>
<li>Node Manager creates the Administration Server process.</li>
</ul>
<ul>
<li>The Administration Server obtains the domain configuration from its config directory.</li>
</ul>
<h3>How Node Manager Starts a Managed Server</h3>
<img class="alignnone wp-image-2424" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/874-460x265.png" alt="Node manager" width="460" height="264" />
<ol>
<li>From the Administration Console, the user issues a start command for MS 1.</li>
</ol>
Note: A stand-alone client can also issue a start command for a Managed Server.
<ol start="2">
<li>The Administration Server issues a start command for Managed Server 1 to the Node Manager on Machine B, providing the remote start properties configured for MS 1.</li>
</ol>
<ol start="3">
<li>Node Manager starts Managed Server 1.</li>
</ol>
Node Manager starts the Managed Server using the same root directory where the Node Manager process is running. To run the Managed Server in a different directory, set the Root Directory attribute in the Server&mdash;&gt;Configuration&mdash;&gt;Server Start console page.
<ol start="4">
<li>Managed Server 1 contacts the Administration Server to check for updates to its configuration information.</li>
</ol>
<ol start="5">
<li>If there are outstanding changes to the domain configuration, Managed Server 1 updates its local cache of configuration data.</li>
</ol>
<h3>How Node Manager Restarts an Administration Server</h3>
<img class="alignnone wp-image-2431" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/884-460x273.png" alt="Node manager" width="425" height="252" />
<ol>
<li>Node Manager determines from the Administration Server process exit code that it requires a restart.</li>
</ol>
<ol start="2">
<li>Node Manager obtains the username and password for starting the Administration Server from the boot.properties file, and the server startup properties from the &lt;server_name&gt;/data/nodemanager/startup.properties file.</li>
</ol>
<ol start="3">
<li>Node Manager starts the Administration Server.</li>
</ol>
<ol start="4">
<li>The Administration Server reads its configuration data and starts up.</li>
</ol>
<h3>How Node Manager Restarts a Managed Server</h3>
<img class="alignnone wp-image-2432" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/894-460x269.png" alt="Node manager" width="456" height="266" />
<ol>
<li>Node Manager determines from Managed Server 1&rsquo;s last known state that it requires restarting.</li>
</ol>
<ol start="2">
<li>Node Manager obtains the username and password for starting Managed Server 1 from the boot.properties file, and the server startup properties from the startup.properties file. These server-specific files are located in the server directory for Managed Server 1.</li>
</ol>
<ol start="3">
<li>Node Manager starts Managed Server 1.</li>
</ol>
Note: Node Manager waits for RestartDelaySeconds after a server instance fails before attempting to restart it.
<ol start="4">
<li>Managed Server 1 attempts to contact the Administration Server to check for updates to its configuration data. If it contacts the Administration Server and obtains updated configuration data, it updates its local cache of the config directory.</li>
</ol>
<ol start="5">
<li>If Managed Server 1 fails to contact the Administration Server, and if Managed Server Independence mode (MSI) is enabled, Managed Server 1 uses its locally cached configuration data.</li>
</ol>
Note: Managed Server Independence mode is enabled by default
<img class="alignnone wp-image-2433" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/904-460x295.png" alt="Node manager" width="452" height="289" />
<ol>
<li>Through the Administration Console, an authorized user issues a shutdown command for Managed Server 1.</li>
</ol>
<ol start="2">
<li>The Administration Server issues the shutdown command directly to Managed Server 1. If it successfully contacts Managed Server 1, Managed Server 1 performs the shutdown sequence described in &ldquo;Graceful Shutdown&rdquo; in Managing Server Startup and Shutdown.</li>
</ol>
<ol start="3">
<li>If in the previous step, the Administration Server failed to contact Managed Server 1, it issues a shutdown command for Managed Server 1 to Node Manager on Machine B.</li>
</ol>
<ol start="4">
<li>Node Manager issues a request to the operating system to kill Managed Server</li>
</ol>
<ol start="5">
<li>The operating system ends the Managed Server 1 process.</li>
</ol>
<h2>Node Manager Configuration Files</h2>
Except where noted, configuration files apply to both Java-based and script-based Node Manager.
&nbsp;<img class="alignnone wp-image-2434" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/917-460x261.png" alt="Node manager configuration" width="461" height="261" />
<h3>nodemanager.properties </h3>
This is the configuration file used by the Java-based version of Node Manager. This file is located in WL_HOME/common/nodemanager, where WL_HOME is the location in which you installed WebLogic Server.
<h3> nodemanager.domains </h3>
This file contains mappings between the names of domains managed by Node Manager and their corresponding directories. This file is located in WL_HOME/common/nodemanager. &nbsp;
<h3>nm_data.properties </h3>
This file stores the encryption data the Node Manager uses as an asymmetric encryption key. The data is stored in encrypted form. This file is located in WL_HOME/common/nodemanager. &nbsp;
<h3>nm_password.properties </h3>
This file stores the Node Manager username and password. This file is located in DOMAIN_HOME/config/nodemanager. &nbsp;
<h3>boot.properties </h3>
Node Manager uses this file to specify user credentials when starting a server. This file is located in DOMAIN_HOME/servers/&lt;server_name&gt;/data/nodemanager. &nbsp;
<h3> startup.properties</h3>
<ul>
<li>Each Managed Server instance has its own startup.properties file with properties that control how Node Manager starts up and controls the server. Node Manager automatically creates this file by using properties passed to Node Manager when the Administration Server was last used to start the server. This allows a Node Manager client or startup scripts to restart a Managed Server using the same properties last used by the Administration Server.</li>
<li>These properties correspond to the server startup attributes contained in ServerStartMBean and the health monitoring attributes in ServerStartMBean.</li>
<li>This file is located in DOMAIN_HOME/servers/&lt;server_name&gt;/data/nodemanager. &nbsp;</li>
</ul>
<h3>server_name.addr </h3>
<ul>
<li>server_name.addr stores the IP address added when a server starts or is migrated. This file is generated after the server IP address is successfully brought online during the migration. Server_name.addr is deleted when the IP address is brought offline. The server IP address is used to validate remove requests to prevent addresses from being erroneously removed while shutting down the server.</li>
<li>This file is located in DOMAIN_HOME/servers/&lt;server_name&gt;/data/nodemanager. &nbsp;</li>
</ul>
<h3>server_name.lck </h3>
<ul>
<li>server_name.lck is generated by each server and contains an internally used lock ID.</li>
<li>This file is located in DOMAIN_HOME/servers/&lt;server_name&gt;/data/nodemanager &nbsp;</li>
</ul>
<h3>server_name.pid </h3>
<ul>
<li>server_name.pid is generated by each server and contains the process ID of the server. Node Manager checks the process ID generated by the server during crash recovery.</li>
<li>This file is located in DOMAIN_HOME/servers/&lt;server_name&gt;/data/nodemanager &nbsp;</li>
</ul>
<h3>server_name.state </h3>
<ul>
<li>server_name.state is generated by the server and contains the server&rsquo;s current state. Node Manager monitors the contents of this file to determine the current state of the server.</li>
</ul>
Note: Do not delete or alter this file. Without this file, the Node Manager cannot determine the current state of the server.
<ul>
<li>This file is located in DOMAIN_HOME/servers/&lt;server_name&gt;/data/nodemanager. &nbsp;</li>
</ul>
<h3> Node Manager Log Files </h3>
Use the Node Manager and WebLogic Server log files to help troubleshoot problems in starting or stopping individual Managed Servers. &nbsp;
<h3> Node Manager Log File</h3>
NodeManagerHome/nodemanager.log, where NodeManagerHome is WL_HOME/common/nodemanager &nbsp;
<h3>Node Manager Server Instance Log Files </h3>
DOMAIN_HOME/servers/&lt;server_name&gt;/logs/&lt;server_name&gt;.out, where DOMAIN_HOME is the location in which you installed your WebLogic Server domain, such as d:beauser_projectsdomains&lt;domain-name&gt; &nbsp;
<h3> Web Logic Server Log Files </h3>
DOMAIN_HOME/servers/&lt;server_name&gt;/logs/&lt;server_name&gt;.log &nbsp;
<h3>Summary:</h3>
<ul>
<li>Overview of the Node Manager</li>
<li>Versions of Node Manager</li>
<li>Accessing Node Manager</li>
<li>How Node Manager Works in the WebLogic Server Environment</li>
<li>Node Manager Configuration &amp; Log Files</li>
</ul>
<h2>Check out our Related Courses</h2>
<ul>
<li><a title="Weblogic Tutorials" href="tutorialsweblogic-tutorials-how-to" target="_blank" rel="noopener">Weblogic Tutorials</a></li>
<li><a title="Introduction to Clustering Weblogic" href="introduction-clustering-weblogic/" target="_blank" rel="noopener">Introduction to Clustering Weblogic</a></li>
<li><a title="Oracle Apex&nbsp; Training In Hyderabad" href="oracle-apex-training/" target="_blank" rel="noopener">Oracle Apex&nbsp; Training In Hyderabad</a></li>
<li><a title="Oracle Weblogic Server Installation" href="weblogic-server-installation/" target="_blank" rel="noopener">Oracle Weblogic Server Installation</a></li>
</ul>

Weblogic Node Manager Overview

node-manager-overview-weblogic

Weblogic Node Manager Configuration

weblogic-node-manager-configuration

We are going to discuss about:
<ul style="text-align: justify;">
<li style="text-align: justify;">UsagWee of Logs</li>
<li style="text-align: justify;">Server Log Files and Domain Log Files</li>
<li style="text-align: justify;">Message Formats &amp; Attributes</li>
<li style="text-align: justify;">Configuring WebLogic Logging Services</li>
<li style="text-align: justify;">Filtering WebLogic Server Log Messages</li>
<li style="text-align: justify;">Using the console to Monitor</li>
</ul>
This chapter describes how you use WebLogic Server logging services to monitor server, subsystem, and application events. It explains how you configure WebLogic Server to write messages to log files and listen for the log messages that WebLogic Server broadcasts. It also describes how to view log messages through the WebLogic Server Administration Console.
Using Logs
WebLogic Server subsystems use logging services to provide information about events such as the deployment of new applications or the failure of one or more subsystems. A server instance uses them to communicate its status and respond to specific events. For example, you can use WebLogic logging services to report error conditions or listen for log messages from a specific subsystem.
<ul style="text-align: justify;">
<li>Logs can aid in the discovery of:
<ul>
<li>frequently accessed resources</li>
<li>activity by day and time interval</li>
<li>amount of data sent and received</li>
<li>IP addresses of users accessing the site</li>
<li>number of actual &ldquo;hits&rdquo;</li>
<li>problems servicing requests</li>
<li>performance statistics</li>
</ul>
</li>
</ul>
Server Log Files and Domain Log Files
Each WebLogic Server instance writes all messages from its subsystems and applications to a server log file that is located on the local host computer. By default, the server log file is located in the logs directory below the server instance root directory; for example, DOMAIN_NAME\servers\SERVER_NAME\logs\SERVER_NAME.log, where DOMAIN_NAME is the name of the directory in which you located the domain and SERVER_NAME is the name of the server.
In addition to writing messages to the server log file, each server instance forwards a subset of its messages to a domain-wide log file. By default, servers forward only messages of severity level NOTICE or higher. While you can modify the set of messages that are forwarded, servers can never forward messages of the DEBUG severity level.
The domain log file provides a central location from which to view the overall status of the domain. The domain log resides in the Administration Server logs directory. The default name and location for the domain log file is DOMAIN_NAME\servers\ADMIN_SERVER_NAME\logs\DOMAIN_NAME.log,
Where DOMAIN_NAME is the name of the directory in which you located the domain and ADMIN_SERVER_NAME is the name of the Administration Server.
Message Formats &amp; Attributes
Log Message Format
When a WebLogic Server instance writes a message to the server log file, the first line of each message begins with #### followed by the message attributes. Each attribute is contained between angle brackets.
Here is an example of a message in the server log file:
####&lt;Sept 22, 2004 10:46:51 AM EST&gt; &lt;Notice&gt; &lt;WebLogicServer&gt; &lt;MyComputer&gt;
&lt;examplesServer&gt; &lt;main&gt; &lt;&lt;WLS Kernel&gt;&gt; &lt;&gt; &lt;null&gt; &lt;1080575211904&gt; &lt;BEA-000360&gt; &lt;Server started in RUNNING mode&gt;
In this example, the message attributes are: Locale-formatted Timestamp, Severity, Subsystem, Machine Name, Server Name, Thread ID, User ID, Transaction ID, Diagnostic Context ID, Raw Time Value, Message ID, and Message Text. (A subsequent section, &ldquo;Message Attributes,&rdquo; describes each attribute.)
Format of Output to Standard Out and Standard Error
When a WebLogic Server instance writes a message to standard out, the output does not include the #### prefix and does not include the Server Name, Machine Name, Thread ID, User ID, Transaction ID, Diagnostic Context ID, and Raw Time Value fields.
Here is an example of how the message from the previous section would be printed to standard out:
&lt;Sept 22, 2004 10:51:10 AM EST&gt; &lt;Notice&gt; &lt;WebLogicServer&gt; &lt;BEA-000360&gt; &lt;Server started in RUNNING mode
In this example, the message attributes are: Locale-formatted Timestamp, Severity, Subsystem, Message ID, and Message Text.
Message Attributes
The messages for all WebLogic Server instances contain a consistent set of attributes. In addition, if your application uses WebLogic logging services to generate messages, its messages will contain these attributes.
<img class="alignnone wp-image-2468" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/983-460x283.png" alt="98" width="471" height="289" />
Message Severity &amp; Messages Forwarded to Domain Log
The severity attribute of a WebLogic Server log message indicates the potential impact of the event or condition that the message reports.
<img class="alignnone wp-image-2469" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/993-460x289.png" alt="99" width="476" height="298" />
Message Catalog
Message catalogs are available in HTML format on e-docs as part of the documentation deliverable. You can search for messages by error number using the search engine.
<img class="alignnone wp-image-2471" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/1002-460x212.png" alt="100" width="504" height="232" />
<img class="alignnone wp-image-2472" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/1012-460x312.png" alt="101" width="445" height="301" />
Configuring WebLogic Logging Services
&nbsp;
Logging Configuration Tasks: Main Steps
The following steps summarize how you configure and filter log messages that WebLogic Server generates. Related documentation and later sections in this guide describe these steps in more detail.
<ol style="text-align: justify;">
<li>Use the Administration Console to manage log files and configure the following logging options:</li>
<li>Domain and server log file name and location, rotation pattern, location of archived log files, and number of log files stored.</li>
</ol>
<ol style="text-align: justify;">
<li>Types of messages that the server sends to standard out.</li>
</ol>
<ol style="text-align: justify;">
<li>Which messages a server instance sends to the domain log.</li>
</ol>
<ol style="text-align: justify;">
<li>Log files for HTTP requests.</li>
</ol>
<ol style="text-align: justify;">
<li>Specify the logging implementation (Java Logging or Log4j).</li>
</ol>
<ol style="text-align: justify;">
<li>Specify message destination and configure filtering log messages by severity level or other criteria. See &ldquo;Filter log messages&rdquo; in the Administration Console Online Help.</li>
</ol>
<ol style="text-align: justify;" start="2">
<li>Alternatively, configure log message filtering on the message handler using the WebLogic Scripting Tool.</li>
</ol>
<ol style="text-align: justify;" start="3">
<li>Filter log messages published by the logger using the Java APIs.</li>
</ol>
Environment -&gt; Servers -&gt; Logging&hellip;
<img class="alignnone wp-image-2473" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/1022-460x316.png" alt="102" width="462" height="317" />
Filtering WebLogic Server Log Messages
WebLogic logging services provide several filtering options that give you the flexibility to determine which messages are written to WebLogic Server log files and standard out, and which are written to the log file and standard out that a client JVM maintains.
<ul style="text-align: justify;">
<li>Log filters provide control over the log messages that get published.</li>
</ul>
<ul style="text-align: justify;">
<li>You can filter out messages of a certain severity level, from a particular subsystem, or according to specified criteria</li>
</ul>
<ul style="text-align: justify;">
<li>You can create separate filters for the messages that each server instance writes to:
<ul>
<li>its server log file</li>
<li>standard out</li>
<li>memory buffer</li>
<li>domain-wide log</li>
</ul>
</li>
</ul>
Create Log Filters 
Step 1:
Domain -&gt; Configuration -&gt; Log Filters and then click on New
<img class="alignnone wp-image-2474" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/1032-460x167.png" alt="103" width="508" height="183" />
Step 2: Specify the Name of the Filter and click on Finish Button and Click on Activate Changes
<img class="alignnone wp-image-2475" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/1042.png" alt="104" width="386" height="313" />
Step 3: Specify the conditions according to the requirement and then apply save and Activate Changes.
<img class="alignnone wp-image-2476" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/1051.png" alt="105" width="450" height="351" />
Assigning a Log Filter to Server
Servers -&gt; Select Server -&gt; Logging -&gt; Advanced and then apply the Filter according to the requirement.
<img class="alignnone wp-image-2477" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/1061-460x283.png" alt="106" width="435" height="267" />
Using the Console to Monitor
The Administration Console offers some monitoring capabilities:
<img class="alignnone wp-image-2478" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/1071-460x114.png" alt="107" width="369" height="91" />
Monitoring Running Servers
<img class="alignnone wp-image-2479" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/1081-460x266.png" alt="108" width="432" height="249" />
<img class="alignnone wp-image-2480" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/1091-460x199.png" alt="109" width="440" height="189" />
<img class="alignnone wp-image-2481" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/1102-460x178.png" alt="110" width="458" height="177" />
Monitoring Individual Servers
Server Status and Threads Monitoring
<img class="alignnone wp-image-2483" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/1113-460x311.png" alt="111" width="429" height="288" />
<img class="alignnone wp-image-2484" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/1122-460x288.png" alt="112" width="452" height="282" />
Check out our Related Courses <a href="https://tekslate.com/tutorials/weblogic-tutorials-how-to/">Weblogic Tutorials</a> <a href="https://tekslate.com/introduction-clustering-weblogic/">Introduction to Clustering Weblogic</a> <a href="https://tekslate.com/oracle-goldengate-training/">Oracle Goldengate Training In Chicago</a> <a href="https://tekslate.com/weblogic-server-installation/">Oracle Weblogic Server Installation</a>
&nbsp;

Logging and Filtering in Weblogic

Logging and Filtering

weblogic-logging-filtering

Work Managers in Weblogic

work-managers-weblogic

weblogic jdbc overview

Weblogic JDBC

jdbc-weblogic

&nbsp;
At the end of this chapter you will be able to:
<ul>
<li>Understand how WebLogic Server JMS is implemented</li>
<li>Configure JMS administered objects using the administration console </li>
<li>Configure persistent messages</li>
<li>Use the WLS administration console to monitor JMS</li>
</ul>
<h3>Message-Oriented Middleware</h3>
<ul>
<li>Message-oriented middleware refers to an infrastructure that supports messaging.</li>
<li>Typical message-oriented middleware architectures define these elements:
<ul>
<li>Message structure</li>
<li>The way to send and receive messages</li>
<li>Scaling guidelines</li>
</ul>
</li>
</ul>
<h2>Point-to-Point (PTP) Queue</h2>
<ul>
<li>Many producers can serialize messages to multiple receivers in a queue.</li>
</ul>
&nbsp; <img class="alignnone wp-image-2578" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/468-460x152.png" alt="PTP Queue" width="466" height="154" />
<h2>Publish-Subscribe Topics</h2>
<ul>
<li>Publishing and subscribing to a topic decouple producers from consumers.</li>
</ul>
<img class="alignnone wp-image-2579" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/477-460x150.png" alt="Publish subscribe" width="492" height="159" /> &nbsp;
<h2>WebLogic Server JMS Features</h2>
<ul>
<li>WebLogic Server JMS supports:
<ul>
<li>PTP and Pub/subdomains</li>
<li>Guaranteed and transactional message delivery</li>
<li>Durable subscribers</li>
<li>Distributed destinations</li>
<li>Recovery from failed servers</li>
</ul>
</li>
</ul>
<h2>&nbsp; JMS Architecture: Connecting</h2>
<img class="alignnone wp-image-2580" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/486-460x180.png" alt="JMS Architecture" width="474" height="185" /> &nbsp;
<h2>JMS Architecture: Sending Messages </h2>
<img class="alignnone wp-image-2581" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/496-460x191.png" alt="JMS Architecture" width="479" height="198" /> &nbsp;
<h2>Transacted Messaging</h2>
<ul>
<li>A JMS client can use JTA to participate in a distributed transaction.</li>
<li>Alternatively, a JMS client can demarcate transactions local to the JMS Session, through a transacted session.</li>
<li>Participation in a transaction is optional.</li>
</ul>
<blockquote>
Inclined to build a profession as Weblogic Developer? Then here is the blog post on, explore <a title="Weblogic Training" href="weblogic-server-administration-training" target="_blank" rel="noopener">Weblogic Training</a>
</blockquote>
<h2>Administrative Tasks</h2>
<img class="alignnone wp-image-2582" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/507-460x119.png" alt="Administrative tasks" width="464" height="119" />
<ul>
<li>Administrative tasks include these:
<ul>
<li>Creating and monitoring JMS Servers</li>
<li>Creating connection factories</li>
<li>Creating and monitoring destinations</li>
<li>Creating JMS stores</li>
<li>Configuring thresholds and quotas</li>
<li>Configuring durable subscriptions</li>
<li>Managing JMS service fail-over</li>
</ul>
</li>
</ul>
<h2>WLS JMS Server</h2>
<ul>
<li>In WLS, the messaging service is implemented through a JMS Server.</li>
<li>A JMS Server receives and distributes messages.</li>
</ul>
<img class="alignnone wp-image-2583" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/5111-460x157.png" alt="WLS JMS Server" width="520" height="177" /> &nbsp;
<h3>Create a JMS Server</h3>
&nbsp; <img class="alignnone wp-image-2584" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/525-460x243.png" alt="JMS Server" width="506" height="266" /> &nbsp;
<h3>Target a JMS Server</h3>
<img class="alignnone wp-image-2585" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/535-460x152.png" alt="JMS Server" width="506" height="167" /> &nbsp;
<h3>Configure a JMS Server</h3>
<img class="alignnone wp-image-2586" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/545-460x281.png" alt="JMS Server" width="472" height="288" /> &nbsp;
<h3>JMS Resources</h3>
<ul>
<li>JMS resources are managed as system modules, application modules, or packaged JDBC resource modules.</li>
</ul>
<img class="alignnone wp-image-2587" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/555-460x203.png" alt="JMS Server" width="473" height="208" /> &nbsp;
<h3>Modular JMS Resource Configuration and Deployment...</h3>
<ul>
<li>JMS configurations in WebLogic Server are stored as modules
<ul>
<li>Defined by an XML file that conforms to the Weblogic-jmsmd.xsd schema</li>
<li>Similar to standard J2EE modules</li>
</ul>
</li>
<li>An administrator can create and manage JMS modules as:
<ul>
<li>Global system resources</li>
<li>Global standalone modules</li>
<li>Modules packaged with an enterprise application</li>
</ul>
</li>
<li>An advantage of modular deployment is simplified migration between environments, such as:
<ul>
<li>From development to integration</li>
<li>From system test to production</li>
</ul>
</li>
<li>You can migrate your application and the required JMS configuration:
<ul>
<li>Without opening an EAR file</li>
<li>Without extensive manual JMS reconfiguration</li>
</ul>
</li>
</ul>
<h2>Connection Factory</h2>
<ul>
<li>A connection factory:
<ul>
<li>Encapsulates connection configuration information</li>
<li>Is used to create pre-configured connections</li>
<li>Is stored in JNDI</li>
<li>Can be targeted to servers or clusters</li>
</ul>
</li>
<li>WLS provides a default connection factory that is bound in JNDI to weblogic.jms.ConnectionFactory.</li>
<li>When a new configuration is required, a new connection factory can be created.</li>
</ul>
<img class="alignnone wp-image-2588" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/565-460x234.png" alt="JMS Connection factory" width="501" height="254" />
<img class="alignnone wp-image-2589" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/575-460x226.png" alt="JMS Connection factory" width="513" height="251" />
<img class="alignnone wp-image-2590" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/585-460x182.png" alt="JMS Connection factory" width="496" height="195" />
<img class="alignnone wp-image-2591" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/595-460x218.png" alt="JMS Connection factory" width="497" height="235" />
<img class="alignnone wp-image-2592" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/605-460x204.png" alt="JMS Connection factory" width="510" height="226" /> &nbsp;
<h3>Configure Connection Factory: Default Delivery</h3>
&nbsp; <img class="alignnone wp-image-2593" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/619-460x203.png" alt="JMS Connection factory" width="491" height="216" /> &nbsp;
<h3>Configure Connection Factory: Client</h3>
<img class="alignnone wp-image-2594" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/625-460x289.png" alt="JMS Connection factory" width="485" height="304" /> &nbsp;
<h3>Configure Connection Factory: Transactions</h3>
<img class="alignnone wp-image-2595" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/635-460x218.png" alt="JMS Connection factory" width="456" height="216" /> &nbsp;
<h3>Configure Connection Factory:&nbsp; Flow Control</h3>
<img class="alignnone wp-image-2596" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/645-460x329.png" alt="JMS Connection factory" width="435" height="310" /> &nbsp;
<h3>Destination</h3>
<ul>
<li>A destination is a lightweight object stored in JNDI.</li>
<li>It is the target on a JMS Server for sending or receiving messages.</li>
<li>The JMS destination types are:
<ul>
<li>Queue</li>
<li>Topic</li>
</ul>
</li>
</ul>
<h3>Create a Queue Destination&hellip;</h3>
<img class="alignnone wp-image-2597" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/655-460x206.png" alt="JMS Connection factory" width="493" height="220" />
<img class="alignnone wp-image-2598" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/665-460x204.png" alt="JMS Connection factory" width="489" height="217" />
<img class="alignnone wp-image-2599" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/675-460x197.png" alt="JMS Connection factory" width="532" height="227" /> &nbsp;
<h2>Threshold and Quota</h2>
<ul>
<li>A threshold and a quota can be set for Server and Destination objects.</li>
<li>A quota is a limit defined for JMS administered objects; it includes these values:
<ul>
<li>The maximum number of bytes that can be stored</li>
<li>The maximum number of messages that can be stored</li>
</ul>
</li>
<li>A threshold is a limit that triggers message paging, flow control, and logged warnings, using:
<ul>
<li>Upper and lower values for the number of bytes</li>
<li>Upper and lower values for the number of messages</li>
</ul>
</li>
</ul>
<h3>Configuring Thresholds and Quotas</h3>
<img class="alignnone wp-image-2600" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/685-460x289.png" alt="Threshold and Quotas" width="494" height="309" />
<h2>Configuring Persistent Messaging &nbsp;</h2>
<h3>Durable Subscribers and Subscriptions</h3>
<ul>
<li>Durable subscribers register durable subscriptions to guarantee message delivery even if subscribers are inactive.</li>
<li>A subscriber is considered active if the Java object that represents it exists.</li>
<li>By default, subscribers are non-durable.</li>
<li>Administrators configure:
<ul>
<li>Where messages are persisted</li>
<li>Persistent connection factories and destinations</li>
</ul>
</li>
</ul>
<h3>When to Use Persistent Messaging</h3>
<ul>
<li>Persistent messaging permits messages in memory to be written out to a persistent store.</li>
<li>Configure persistent messaging if:
<ul>
<li>Development requires durable subscriptions (use durable subscribers in the application)</li>
<li>You require that in-progress messages persist across server restarts</li>
</ul>
</li>
</ul>
<h3>How a Durable Subscription Works</h3>
<ul>
<li>If a subscriber client is active, messages are delivered normally:</li>
<li>When the client becomes active again, its ID is used to retrieve and redeliver messages.</li>
</ul>
&nbsp; <img class="alignnone wp-image-2601" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/695-460x164.png" alt="Durable subscription" width="492" height="174" /> &nbsp;
<h3>Configure a Durable Subscription</h3>
<ul>
<li>To configure durable subscriptions, an administrator must:
<ul>
<li>Create and configure a JMS store</li>
<li>Configure connection factories or destinations as persistent</li>
<li>Associate the JMS store with the JMS Server</li>
</ul>
</li>
<li>The JMS store can be configured to use either:
<ul>
<li>A file store</li>
<li>A JDBC store (a connection pool)</li>
</ul>
</li>
</ul>
<h3>Create a JMS File Store&hellip;</h3>
<img class="alignnone wp-image-2602" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/704-460x242.png" alt="70" width="474" height="248" />
&nbsp; <img class="alignnone wp-image-2603" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/719-460x193.png" alt="JMS" width="471" height="196" /> &nbsp;
<h3>Create a JMS JDBC Store&hellip;</h3>
<ul>
<li>To configure JMS JDBC persistence:
<ul>
<li>Create a JDBC DataSource.</li>
<li>Create a JMS store and refer to the JDBC DataSource.</li>
<li>Refer to the JMS store from the JMS Server configuration.</li>
</ul>
</li>
<li>The required infrastructure (tables, and so on) is created automatically.</li>
</ul>
&nbsp; <img class="alignnone wp-image-2604" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/725-460x293.png" alt="JMS" width="477" height="304" /> &nbsp;
<h3>Assign a Store to a JMS Server</h3>
<img class="alignnone wp-image-2605" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/735-460x223.png" alt="JMS Server" width="480" height="232" /> &nbsp;
<h2>Persistent Connection Factory </h2>
<img class="alignnone wp-image-2606" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/745-460x304.png" alt="Connection factory" width="475" height="314" /> &nbsp;
<img class="alignnone wp-image-2607" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/755-460x274.png" alt="Connection factory" width="479" height="284" /> &nbsp;
<h3>Monitoring JMS in WLS Statistics for JMS Objects</h3>
<ul>
<li>Statistics are provided for the following JMS objects:
<ul>
<li>JMS servers</li>
<li>Connections</li>
<li>Destinations</li>
</ul>
</li>
</ul>
<h3>Monitor JMS Servers&hellip;</h3>
<img class="alignnone wp-image-2608" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/765-460x199.png" alt="JMS Server" width="493" height="212" />
<img class="alignnone wp-image-2609" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/775-460x200.png" alt="JMS Server" width="485" height="210" /> &nbsp;
<h3>Monitor Destinations</h3>
<img class="alignnone wp-image-2610" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/785-460x173.png" alt="JMS Server" width="474" height="177" /> &nbsp;
<h3>Summary: </h3>
In this chapter, we learned how to:
<ul>
<li>Understand messaging concepts</li>
<li>Understand WebLogic Server&rsquo;s JMS support</li>
<li>Configure JMS servers, queues, and topics</li>
<li>Monitor JMS servers, queues, and topics</li>
</ul>
<h2>Check out our Related Courses </h2>
<ul>
<li><a title="Weblogic Tutorials" href="tutorialsweblogic-tutorials-how-to" target="_blank" rel="noopener">Weblogic Tutorials</a></li>
<li><a title="Introduction to Clustering Weblogic" href="introduction-clustering-weblogic/" target="_blank" rel="noopener">Introduction to Clustering Weblogic</a></li>
<li><a title="WebLogic Server Admin Training in Bangalore" href="weblogic-server-administration-training/" target="_blank" rel="noopener">WebLogic Server Admin Training in Bangalore</a></li>
<li><a title="Oracle Weblogic Server Installation" href="weblogic-server-installation/" target="_blank" rel="noopener">Oracle Weblogic Server Installation</a> &nbsp; &nbsp; &nbsp;</li>
</ul>

Weblogic JMS (Java Message Service)

jms-java-message-service-weblogic

Security in Weblogic

Security

weblogic-security

Performance and Tuning in Weblogic

Performance and Tuning

weblogic-performance-tuning

Trouble Shooting in WebLogic

trouble-shooting-weblogic

&nbsp;
At the end of this chapter you will be able to:
<ul>
<li>Cluster Introduction and Architecture</li>
<li>Networks and Clusters</li>
<li>Cluster Communication</li>
</ul>
<h2>Definition: Clustering</h2>
<ul>
<li>A cluster is a group of WebLogic Server instances, working in coordination.</li>
</ul>
&nbsp; <img class="alignnone wp-image-2701" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/1216-460x213.png" alt="Clustering" width="437" height="201" /> &nbsp;
&nbsp;
<h3>Benefits of Clustering</h3>
<ul>
<li>There are two main benefits of clustering together WebLogic servers:
<ul>
<li>Scalability</li>
<li>High-Availability</li>
</ul>
</li>
</ul>
<ul>
<li>Scalability allows you to add and remove servers without disrupting current services.</li>
</ul>
<ul>
<li>High-Availability ensures that when a server (in a cluster) fails, there are other servers to take over the work so the client is not affected.</li>
</ul>
<h3>Key Capabilities:</h3>
The key capabilities of a WebLogic cluster are:
<ul>
<li>Application Failover</li>
</ul>
When an object in an application is performing a task becomes unavailable, another object will take over and finish the job.
<ul>
<li>Site Failover</li>
</ul>
When all the services and applications in a single site fail they can switch to a separate site and continue processing.
<ul>
<li>Server Migration</li>
</ul>
When a server fails, pinned services can be migrated to another server in a cluster.
<ul>
<li>Load Balancing</li>
</ul>
The even distribution of tasks and communications across multiple servers. &nbsp;
<blockquote>
Inclined to build a profession as Weblogic Developer? Then here is the blog post on, explore <a title="Weblogic Training" href="weblogic-server-administration-training" target="_blank" rel="noopener">Weblogic Training</a>
</blockquote>
<h2>Cluster Architecture:</h2>
<ul>
<li>Applications are generally broken into multiple tiers, each representing their distinct functionality:
<ul>
<li>Web tier</li>
<li>Presentation tier</li>
<li>Business or object tier</li>
</ul>
</li>
</ul>
<ul>
<li>WebLogic provides clustering support for all three tiers.</li>
<li>Other services, such as JMS and <a href="jdbc-weblogic" target="_blank" rel="noopener">JDBC</a>, can take advantage of clusters but load-balancing and failover is a little different.</li>
</ul>
<h3>Deciding on Cluster Architecture</h3>
Good architecture is somewhat subjective but there are a few global considerations:
&nbsp; &nbsp; &nbsp; &nbsp;1.&nbsp; Performance
&nbsp; &nbsp; &nbsp; &nbsp; 2. Efficient replication
&nbsp; &nbsp; &nbsp; &nbsp; 3. Optimal load balancing
&nbsp; &nbsp; &nbsp; &nbsp; 4. Effective failover
&nbsp; &nbsp; &nbsp; &nbsp; 5. Reliable communication
<ul>
<li>There are two primary cluster architectures to choose from:
<ul>
<li>Basic Cluster architecture</li>
<li>Multi-tier architecture</li>
</ul>
</li>
</ul>
<h2>Basic Cluster Architecture</h2>
Basic cluster architecture combines static HTTP, presentation logic, business logic, and objects into one cluster.
<img class="alignnone wp-image-2702" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/1310-460x255.png" alt="Basic cluster architecture" width="408" height="226" /> &nbsp;
<h2>Multi-Tier Cluster Architecture</h2>
The Web tier and the business logic with services can be separated into two clusters.
<img class="alignnone wp-image-2703" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/147-460x245.png" alt="Multi tier architecture" width="434" height="230" /> &nbsp;
<h3>When to Use Multi-tier Architecture</h3>
<ul>
<li>The multi-tier cluster is recommended for Web Applications that require:
<ul>
<li>Load balancing for method calls to clustered EJBs</li>
<li>Flexibility for load balancing between servers that provide</li>
</ul>
</li>
</ul>
<ul>
<li>HTTP content and servers that provide clustered objects
<ul>
<li>Higher availability (fewer single points of failure)</li>
<li>More flexible security</li>
</ul>
</li>
</ul>
<h3>Basic Cluster Architecture Advantages and Disadvantages</h3>
<ul>
<li>The basic cluster architecture has these advantages:
<ul>
<li>Easy administration</li>
<li>Flexible load balancing</li>
<li>Robust security</li>
</ul>
</li>
</ul>
<ul>
<li>The basic cluster architecture has these disadvantages:
<ul>
<li>Cannot load balance EJB method calls</li>
<li>Load balancing across the tiers may become unbalanced</li>
</ul>
</li>
</ul>
<h3>Multi-tier Advantages and Disadvantages:</h3>
<ul>
<li>The multi-tier architecture has these advantages:
<ul>
<li>Improved load balancing</li>
<li>Load balancing of EJB methods</li>
<li>Higher availability</li>
<li>Improved security options</li>
</ul>
</li>
</ul>
<ul>
<li>The multi-tier architecture has these disadvantages:
<ul>
<li>Can create a bottleneck when presentation tier makes frequent calls to the business logic</li>
<li>Increased licensing cost</li>
<li>Added firewall configuration complexity</li>
</ul>
</li>
</ul>
<h2>Proxy Servers</h2>
<ul>
<li>Proxy servers are used to provide load balancing and failover for a cluster.
<ul>
<li>Are the client&rsquo;s first level of interaction with the cluster</li>
<li>Give the cluster its single server appearance</li>
</ul>
</li>
<li>A proxy server can be either software-based or hardware-based.</li>
<li>A software-based proxy server may be an internal WebLogic servlet or a 3rd party application.</li>
<li>A hardware-based proxy server is typically a physical load balancer.</li>
</ul>
<h2>Basic Cluster Proxy Architecture:</h2>
Similar to the basic cluster architecture, except for static content, is hosted on non-clustered HTTP servers.
<img class="alignnone wp-image-2704" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/157-460x224.png" alt="Basic Cluster Proxy architecture" width="419" height="204" /> &nbsp;
<h2>Multi-Tier Cluster Proxy Architecture</h2>
Similar to the multi-tier cluster architecture, except for static content, is hosted on non-clustered HTTP servers.
<img class="alignnone wp-image-2705" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/167-460x220.png" alt="Multi-tier cluster proxy architecture" width="447" height="213" /> &nbsp;
&nbsp;
<h2>WLS HttpClusterServlet</h2>
<img class="alignnone wp-image-2706" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/177-460x256.png" alt="WLS Http Cluster servlet" width="437" height="242" /> &nbsp;
<h3>WLS Plug-Ins&hellip;</h3>
<ul>
<li>WLS is compatible with major Web servers using the following plug-ins:
<ul>
<li>Sun Java System Web Server plug-in (formerly Netscape iPlanet or Sun One Web Server)</li>
<li>IIS plug-in (Microsoft IIS)</li>
<li>Apache plug-in</li>
</ul>
</li>
</ul>
<ul>
<li>Plug-ins:
<ul>
<li>Delegate dynamic content requests to WLS</li>
<li>Round-robin across a cluster</li>
<li>Support routing based on URL path or on the MIME type of the requested file or both</li>
<li>Route HTTP requests to back-end WLS instances based on session cookie or URL rewriting</li>
<li>Avoid failed servers in the cluster</li>
</ul>
</li>
</ul>
<h3>Proxy Plug-in Vs. Load Balancer</h3>
<ul>
<li>There are many advantages to using a physical load balancer instead of the proxy plug-in:
<ul>
<li>No need to configure client plug-ins</li>
<li>Eliminating the proxy layer reduces the number of connections</li>
<li>The availability of more sophisticated load balancing algorithms</li>
</ul>
</li>
<li>There are a number of disadvantages as well:
<ul>
<li>Additional administration</li>
<li>Explicit configuration of &ldquo;sticky&rdquo; sessions for stateful web Applications</li>
</ul>
</li>
</ul>
<h3>Architecture Recommendations</h3>
<ul>
<li>If possible, place static web content on separate web servers in the DMZ.</li>
<li>Use combined tier architecture if your presentation and control tier makes multiple invocations of the business tier.</li>
<li>Make sure that your architecture choice supports passing active and passive cookies between the cluster and client application.</li>
</ul>
<h3>Clusterin Networks</h3>
<ul>
<li>WebLogic Server clusters can be created in three different kinds of networks:
<ul>
<li>Local Area Networks</li>
<li>Metropolitan Area Networks</li>
<li>Wide Area Networks</li>
</ul>
</li>
</ul>
<ul>
<li>When you are configuring your cluster, you will need to keep in mind the type of network you are using.</li>
</ul>
<h2>Local Area Networks</h2>
<ul>
<li>A local area network (LAN) serves a local set of computers.
<ul>
<li>They usually use high quality, high-speed communication links</li>
<li>Typical data transmission speeds are 100 megabits/second</li>
</ul>
</li>
<li>Most clusters exist within a single LAN</li>
</ul>
&nbsp; <img class="alignnone wp-image-2707" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/187-460x126.png" alt="LAN" width="435" height="119" /> &nbsp;
&nbsp;
<h2>Metropolitan Area Networks:&nbsp;</h2>
<ul>
<li>A Metropolitan Area Network (MAN) is a network that usually spans a campus or a city.</li>
<li>You can have different clusters located reasonably close to each other within a MAN.</li>
</ul>
<img class="alignnone wp-image-2708" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/197-460x141.png" alt="MAN" width="435" height="132" /> &nbsp;
<h2>Wide Area Networks</h2>
<ul>
<li>A Wide Area Network (WAN) usually spans a wider geographical area and can be made up of smaller MANs and Local Area Networks (LAN).</li>
<li>You can have different clusters located in different regions within a WAN.</li>
</ul>
A cluster can be located in different LANs within a MAN or within a WAN
<img class="alignnone wp-image-2709" src="https://newtekslateassets.s3.us-west-2.amazonaws.com/wp-content/uploads/2014/11/207-460x111.png" alt="WAN" width="433" height="104" /> &nbsp; &nbsp;
<h2>Cluster Communication</h2>
<h3>Server Communication in a Cluster</h3>
<ul>
<li>WebLogic Server instances in a cluster communicate with one another using two different techniques:
<ul>
<li>Multicast (UDP)</li>
<li>Sockets (peer-to-peer TCP)</li>
</ul>
</li>
<li>IP multicast broadcasts one-to-many communications among clustered instances.</li>
<li>IP sockets are used for peer-to-peer communications between servers.</li>
</ul>
<h3>Detecting a Failure: &nbsp;</h3>
<ul>
<li>WebLogic clusters detect the failure of a server instance in the following ways:
<ul>
<li>Through the use of IP sockets</li>
<li>Through the WebLogic server heartbeat</li>
</ul>
</li>
</ul>
<ul>
<li>If a server in the cluster unexpectedly closes its socket, it will be marked as "failed" and its services will not be used.</li>
<li>Server instances use multicast to broadcast heartbeats every 10 seconds to other server instances in the cluster.
<ul>
<li>If three heartbeats are missed from a peer server, the server is marked as "failed" and its services will not be used</li>
</ul>
</li>
</ul>
<h3>One-to-Many Communications</h3>
<ul>
<li>WebLogic Server uses one-to-many communication for:</li>
</ul>
<ul>
<li>Cluster-wide JNDI updates</li>
<li>Cluster &ldquo;heartbeats&rdquo;</li>
</ul>
<ul>
<li>Because all one-to-many communications occur over IP multicast, when designing a cluster, consider these factors:
<ul>
<li>If your cluster spans multiple subnets, your network must be configured to reliably transmit messages</li>
<li>A firewall can break IP multicast transmissions</li>
<li>The multicast address should not be shared with other applications</li>
<li>Multicast storms may occur</li>
</ul>
</li>
</ul>
<h3>Peer-to-Peer Communications:</h3>
<ul>
<li>WebLogic Server uses peer-to-peer communications for:</li>
</ul>
<ul>
<li>Accessing non-clustered objects that reside on a remote server instance in the cluster</li>
<li>Replicating HTTP session states and stateful session EJB states between a primary and a secondary server</li>
<li>Accessing clustered objects that reside on a remote server instance (typically, in a multi-tier cluster architecture)</li>
</ul>
<h3>Multi-Tier Communications:</h3>
<ul>
<li>Multi-tier clusters will require more IP Sockets than a combined-tier cluster:
<ul>
<li>One socket for replicating session states</li>
<li>One socket for each WebLogic Server in the EJB cluster, for accessing remote objects</li>
</ul>
</li>
<li>As an example, using a three-node cluster, the worst-case scenario would be five open sockets per server:
<ul>
<li>One primary and secondary replicated session</li>
<li>Each server simultaneously invokes a remote EJB method on each node in the cluster</li>
</ul>
</li>
</ul>
<h3>Communication in a WAN:</h3>
<ul>
<li>In a WAN, the servers in your cluster may span multiple subnets.</li>
</ul>
<ul>
<li>In order for multicast messages to reliably transmit across the WAN your network must meet the following requirements:
<ul>
<li>Full support of IP multicast packet propagation</li>
<li>A network latency that allows for multicast messages to reach their destination in 200 to 300 milliseconds</li>
<li>A multicast time-to-live value high enough to ensure that routers do not discard multicast packets</li>
</ul>
</li>
</ul>
<h2>Summary:</h2>
In this chapter we discussed:
<ul>
<li>Cluster Introduction and Architecture</li>
<li>Networks and Clusters</li>
<li>Cluster Communication</li>
</ul>
<h2>Check out our Related Courses</h2>
<ul>
<li><a title="Weblogic Tutorials" href="tutorialsweblogic-tutorials-how-to" target="_blank" rel="noopener">Weblogic Tutorials</a></li>
<li><a title="Oracle Goldengate Training In Hyderabad" href="oracle-goldengate-training/" target="_blank" rel="noopener">Oracle Goldengate Training In Hyderabad</a></li>
<li><a title="Oracle Weblogic Server Installation" href="weblogic-server-installation/" target="_blank" rel="noopener">Oracle Weblogic Server Installation</a> &nbsp;</li>
</ul>

Introduction to Weblogic Clustering

Introduction to Clustering

introduction-clustering-weblogic