WebLogic-real-Life Documentation

Transcription

1 WebLogic-real-Life Documentation Release 0.1 Mathieu COAVOUX September 06, 2016

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3 Startup and Shutdown 1 Startup WebLogic Startup and Shutdown Classes Java Messaging Service Connection Factory Distributed Queue Real life i

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5 Contents: Startup and Shutdown 1

6 2 Startup and Shutdown

7 CHAPTER 1 Startup WebLogic Depending on your configuration, servers can take time to startup. WebLogic deploys its application after two phases. # Phase 1: The application has the prepare status. At this step WebLogic controls package integrity and ensure the application can be deployed. We can meet errors at this step if a package has been corrupted while transferring from the Admin server to managed servers. This phase includes several steps. ## STATE_NEW : application has never been uploaded before. ## STATE_PREPARED : application package is available on managed servers. ## STATE_ADMIN # Phase 2: The application has the active status. WebLogic deploys the application in all managed servers of the cluster. Real life: On a WebLogic 12c platform we corrupted our WAR application in different ways. You can find below results of theses tests Test description Deployment status Application available Delete plan.xml Active Yes Delete web.xml Active Yes Delete weblogic.xml Active Yes Corrupt war file with dd command Active No Web application accessing a datasource which doesn t exists Failed No 1.1 Startup and Shutdown Classes Startup classes and shutdown classes are loaded when the server bootup. Depending on the deployment order the class can be loaded before or after other deployments and services StartLogger example Description In this example we developed a class named DatabaseLogger which writes the current date into t_start and a class named StartServlet which calss DatabaseLogger. When configuring a startup class in WebLogic console, the managed server will try to call the method main into this class. If we do not write this method main the following error will occur during startup: java.lang.nosuchmethodexception: app.startservlet does not define 'public static void main(string[])' 3

8 Configuration To configure a class into startup we first need to add the package to classloader. A quick and dirty solution is to add lines below to setdomainenv.sh CLASSPATH="${CLASSPATH}:/opt/wls12210/user_projects/domains/DOMAIN-2/upload/StartLoggerProject.jar" export $CLASSPATH Then you can add the class to start to Weblogic configuration with the following steps: Click Environment and Startup and Shutdown Classes Click New and select Startup Class Add Startup name to display in WebLogic console and startup class name to boot Select target and press finish For our example we set the following configuration If startup class failed to load server will shutdown. This is not the default value but can be usefull to know at the begining your application is not able to initialize Source code StartLogger class contains a single main method which calls writestarttime method from DataSourceClient 4 Chapter 1. Startup WebLogic

9 package fr.comprehensiveit.weblogic; public class StartLogger { public static void main(string args[]) throws InterruptedException { System.out.println("StartLogger"); DatabaseLogger dsc = new DatabaseLogger(); int myresult = dsc.writestarttime(); System.out.println("StartLogger result:"+myresult+"\n"); } } DataSourceClient writes current date and time in t_start2 column. We let WebLogic manages database connection by using testds datasource. package fr.comprehensiveit.weblogic; import java.sql.preparedstatement; import java.sql.resultset; import java.sql.sqlexception; import java.util.hashtable; import javax.naming.context; import javax.naming.initialcontext; import oracle.jdbc.oracleconnection; public class DatabaseLogger { public int writestarttime() { OracleConnection conn=null; javax.sql.datasource ds=null; Hashtable env = new Hashtable(); //Define weblogic context factory and URL env.put( Context.INITIAL_CONTEXT_FACTORY, "weblogic.jndi.wlinitialcontextfactory" ); env.put(context.provider_url, "t3:// :23001"); PreparedStatement psmt; try { Context context=new InitialContext( env ); //Try to get datasource testds from WebLogic ds=(javax.sql.datasource) context.lookup ("testds"); //Get a connection from pool conn=(oracleconnection) ds.getconnection(); String sql = "insert into t_start2 (d_start) values(current_timestamp)"; psmt = conn.preparestatement(sql); //Execute query psmt.executequery(); conn.commit(); conn.close(); }catch(exception ex){ try { conn.rollback(); }catch(exception ex2) { System.out.println("Can not rollback prepared statement. This might occur if co } //handle the exception ex.printstacktrace(); return 1; } return 0; 1.1. Startup and Shutdown Classes 5

10 } } Startup Before starting WebLogic we can check that no entry exists into t_start2 SQL> select * from webusr.t_start2; no rows selected During WebLogic bootup we can notice that WebLogic invoked the main method We can also verify if the entry exists SQL> select * from webusr.t_start2; ID D_START AUG PM CacheRetriever example In this example we are showing how startup class can be used. We developed a servlet which requires quite lot of informations from database and store it to cache before displaying result to user. This servlet will take time at the first run as cache is not initialized. Then we developed a jar that we initialize cache at the bootup. Hence when servlet is called the cache is initialized already. 6 Chapter 1. Startup WebLogic

11 CHAPTER 2 Java Messaging Service 2.1 Connection Factory Description A connection factory object is an administration object available under a JMS Module. A connection factory is used to access to queues or topics configured into this module. The connection factory is handling connections and is accessed by consumers and providers by its JNDI name Configuration Load Balance Load Balancing Enabled: When enabled this load balance producers between JMS servers. All messages sent by producers will be dispatched between JMS servers even messages issued during a single connection. Note this option will not dispatch consumers between JMS servers. Server Affinity Enabled: this option handles producers AND consumers connections. When enabled producers or consumers will send or get messages from the same JMS server. Hence if Load Balancing Enabled option and Server Affinity Enabled option are both enabled the producer will send all its messages to the same JMS server during the connection. The next connection it will send all messages to another JMS server. 2.2 Distributed Queue Description Distributed queue is a queue deployed to multiple JMS servers. As this queue is distributed some options can be configured to handle connection and messages in the cluster. If a consumer is connected to a JMS server which has no message in its queue all others members of the cluster will forward messages to this JMS server. 2.3 Real life As explain above consumers are not load balanced by the connection factory. If the consumer is deployed on the same server as the queue hence the connection factory will direct this consumer to the current server queue. 7

12 Below the example of Kyko application Kyko application Kyko application has two WebLogic cluster and each cluster has four WebLogic server. First architecture In the first architecture of our application the architect designed a single queue in the cluster 2 where all messages types have been stored. Bridges from cluster 1 selected their messages according to types and put them into the associated queue. Two major issues were encountered with this architecture: Bridge consumers were not dispatched smoothly : some consumers of type T1 were connected twice on a WebLogic server and some others servers haven t any consumer. Therefore some messages stored in some queues were not retrieve by cluster 1 Repetitive disconnection : as bridge selected some messages into the remote queue, it reaches often the maximum idle time as no message were fetched. Second architecture In the second architecture we have created a new distributed queue into cluster 1 to fix the problem of bridge disconnection but unfortunately the other issue remained. The connection factory CF1 was configure with the Load balance enabled and server affinity disabled. We disabled the server affinity to avoid to receive all messages on the same JMS server for the queue CL1-DQ1-ALL. 8 Chapter 2. Java Messaging Service

13 Last architecture In the last architecture we have created a new connection factory CF2 with the server affinity enabled to force bridges to connect to their own JMS server Real life 9

14 10 Chapter 2. Java Messaging Service