181.Explain about WebLogic Production Redeployment?
- Production redeployment:
- Allows two versions of a single Web application or module to run simultaneously
- Requires you to include unique version information either:
- Within the application’s META-INF/MANIFEST.MF file
- As part of the deployment process
- When a new version is redeployed, WLS automatically:
- Routes existing clients to the prior (retired) version
- Routes new clients to the new version
- Undeploys the prior version when all existing clients finish their work or their conversations time out
182.What are the Requirements and Restrictions for Production Redeployment in WLS?
- Production redeployment is supported for:
- Stand-alone Web Application (WAR) modules and Enterprise Applications (EARs) whose client accesses the application via a Web application (HTTP)
- Enterprise Applications that are accessed by inbound JMS messages from a global JMS destination, or from inbound JCA requests
- All types of Web Services, including conversational and reliable Web Services
- Production redeployment is not supported for:
- Stand-alone EJB or Resource Archive (RAR) modules
- Applications that use JTS drivers
- Applications that obtain JDBC data sources via the DriverManager API instead of using the JNDI lookup
- Applications that include the EJB 1.1 container-managed persistence (CMP) EJBs
- A deployed application must specify a version number.
- WLS can host a maximum of two different versions of an application at one time.
- When you are redeploying a new version of an application, the following features cannot change:
- Deployment targets
- Security model
- Persistent store settings
183.Redeploying Versus Distributing an applications in WLS?
- Distributing is an alternative to deploying an application.
- Distributing an application prepares it for deployment by copying its files to all target servers and validating the files.
- You can start a distributed application in Administration mode. Access to the application is then restricted to a configured Administration channel.
- Distributing a new version of the application makes it available for testing before being released for general consumption.
- Redeploying a new version of an application places the application immediately into use and makes it available to new client requests.
184.How will you Distributing a New Application Version in WLS?
- Use the weblogic.Deployer –distribute command.
- After the application is distributed, start the application in Administration mode.
- Test the application.
- When ready, start the application (without using –adminmode).
- Optionally set a retirement timeout for the older version of the application.
185.How will you Create MANIFEST.mf file for Production Redeployment?
- Create MANIFEST.mf with the following contents:
Specification-Title: Java Utility Classes
Specification-Vendor: Sun Microsystems, Inc.
Implementation-Vendor: Sun Microsystems, Inc.
- Then add an entry for WLS versioning:
186.What is a cluster Definition?
- A cluster is a group of Oracle WebLogic Server instances that work in coordination.
- Clustering provides:
- High availability
- Load balancing
187.What Is a Cluster?
- Is a logical group of Oracle WebLogic Servers within a domain
- Supports features to
- Whole servers
- Web applications/services
- EJB applications
- Is transparent to a client
188.What are the Benefits of Clustering?
- There are two main benefits of clustering together Oracle WebLogic Servers:
- High availability
- Scalability is the ability to provide more capacity for an application, in this case, by adding additional servers without having to make major architectural changes.
- High availability ensures that when a server (in a cluster) fails, there are other servers to take over the work, so that the client is not affected.
189.What are the Key Capabilities of clustering?
The key capabilities of a WebLogic cluster are:
- Application failover
- When an object in an application that is performing a task becomes unavailable, another object takes over and finishes
- Site failover
- When all the services and applications in a single site fail, they can switch to a separate site and continue processing.
- Server migration
- When a server fails, pinned services can be migrated to another server in a cluster.
- Load balancing
- Tasks and communications are evenly distributed across multiple servers.
190.Explain about Cluster Architecture?
- Applications are generally broken into multiple tiers, each representing its distinct functionality:
- Web tier
- Presentation tier
- Business or object tier
- WebLogic provides clustering support for all three tiers.
- Other services, such as JMS and JDBC, can take advantage of clusters but load-balancing and failover is a little different.