Configure Server Environments – Questionnaire 5

• What are the guidelines for the location of CacheDirectory attribute when configuring for high Availability.

  The location of the CacheDirectory attribute should be a local directory, even when configuring for high availability
  

• What happens if the filestore native wlfileio driver cannot be loaded.

  If the file store native wlfileio driver cannot be loaded, the store automatically runs in an alternate specialized Direct-Write policy mode.
  

• Explain Direct-Write policy

  When the Direct-Write policy is selected, WebLogic Server writes synchronously to a primary set of files in the location defined by the Directory attribute of the file store configuration using a native I/O wlfileio driver
  

• Explain Cache-Flush Policy

  When the Cache-Flush policy is selected, WebLogic Server enables the default file write behavior of the operating system and storage device, which typically includes caching and scheduling file writes, but forces a flush of the cache to disk before completing a transaction.
  

• Is Cache-Flush Policy transactionally safe

  It is transactionally safe
  

• What Synchronous Write policy provide lower runtime performance and in what cases

  Tends to provide lower runtime performance than the direct-write policies in typical use cases, except in those cases with large numbers of simultaneous producers or consumers.
  

• Explain Disabled Policy

  When the Disabled policy is selected, WebLogic Server relies on the default file write behavior of the operating system and storage device. In most cases, file writes are cached in memory and are scheduled for writing instead of being directly written to disk.
  

• What are the drawbacks of Disabled policy and why

  Possibly losing sent messages or generating duplicate received messages (even if messages are transactional) in the event of an operating system crash or a hardware failure. This is because transactions are complete as soon as their writes are cached in memory, instead of waiting for the writes to successfully reach the disk.
  

• When do we see failures in case of Disabled policy

  Simply shutting down an operating system or killing a WebLogic Server process does not generate these failures, as an OS flushes all outstanding writes under these circumstances during a normal shutdown. Instead, these failures can be emulated by abruptly shutting the power off to a busy server.
  

• What does JDBC TLOG store contains and what are its benefits

  JDBC TLOG stores persist transaction logs to a database, which provides the following benefits:
  ■ Leverages replication and HA characteristics of the underlying database.
  ■ Simplifies disaster recovery by allowing the easy synchronization of the state of the database and TLOGs.
  ■ Improved Transaction Recovery service migration as the transaction logs to do not need to be migrated (copied) to a new location.
  

• Can multiple weblogic servers share same JDBC TLOG store

  Only one JDBC TLOG store can be configured per WebLogic Server. Conversely, multiple WebLogic Servers can not share a JDBC TLOG store.
  

• Can JDBC TLOG data store use a data source that supports global transactions

  You cannot use a data source that is configured to use an XA JDBC driver or is configured to support global transactions. Use a non-XA data source.
  

• What is the relationship between database used to store TLOG information and the server startup.

  The database used to store the TLOG information must be available at server startup. If the database is not available, the WebLogic Server instance will fail to boot.
  

• What happens if the database used to store TLOG inforamtion goes down, while weblogic server is running

  If the JDBC TLOG store becomes unavailable, the JTA health state transitions to FAILED and any global transactions will fail. In turn, the server life-cycle changes to FAILED.
  

• What is the status of pending transactions if the TLOG store is changed from one store type to another and from one location to another.

  If the TLOG store is changed from one store type to another or from one location to another, the change takes effect only after reboot and all pending transactions in the old store are not be copied to the new store. You must ensure there are no pending transactions before changing the TLOG store type or location.
  

• What is the default JDBC store database table name

  The JDBC store database contains a database table, named WLStore, that is generated automatically and is used internally by WebLogic Server.
  

• What is the status of JDBC data stores, when the the Database becomes failed or unavailable.

  WebLogic Server provides robust JDBC data sources that can automatically reconnect to failed databases after they come back online, without requiring you to restart WebLogic Server.
  TestConnectionsOnReserve=”true”
  TestTableName=”SYSTABLES”
  ConnectionCreationRetryFrequencySeconds=”600″
  

• What is the transaction type when we use JDBC persistent Store

  Whenever you are using a JDBC store and a database (even if it is the same database where the JMS messages are stored), then it is two-phase commit transaction.
  

• What is the recommendation to improve performance under heavy JDBC Store I/O loads.

  Under heavy JDBC store I/O loads, you can improve performance by configuring a JDBC store to use multiple JDBC connections to concurrently process I/O operations.
  

• How do you enable I/O Multithreading for JDBC Stores

  To enable I/O multithreading, set the Worker Count attribute to an integer value greater than 1. The default value of this configuration property is 1 and disables this option.
  

• What is the Worker Count attribute

  The Worker Count attribute specifies the number of worker threads the JDBC store uses to process store I/O. Each worker thread acquires one JDBC connection from the configured data source pool when the store is opened.
  

• What is the Oracle recommendation to the Oracle database, when I/O Multithreading is used.

  To reduce contention on Oracle databases, Oracle recommends rebuilding the primary key index into a reverse key index when I/O multithreading is used.
  Oracle recommends reverse indexes for I/O multithreading and non-reverse indexes for single threaded I/O.
  

• At a high level, what are the different systems that can be monitored for a persistent store

  You can monitor statistics for each existing persistent store and for each open store connection.
  

• What is the criteria for store utility to be executed for Administering Persistent Store

  The store utility operates only on a store that is not currently opened by a running server instance. This utility can be run from a Java command line or from WebLogic Scripting Tool (WLST).
  

• What are the most common use of Store utility for Store Administration.

  The most common uses-cases for store administration are for compacting a file store to reduce its size and for dumping the contents of a file store of JDBC store to an XML file for troubleshooting purposes
  

• What are the limitations of Persistent Store
  • A persistent file store should not be opened simultaneously by two server instances;
    
  • Two JDBC stores must not share the same database table, because this will result in data corruption.
    
  • A persistent store may not survive arbitrary corruption.
    
  • A file store may return exceptions when its disk is full.
    
• What is the configuration to be taken care, when multiple servers try to access the same store at the same time.

  It is the responsibility of the administrator to ensure that the persistent store is being used in an environment in which multiple servers will not try to access the same store at the same time. (Two file stores are considered the “same store” if they have the same name and the same directory.)
  

Configure Server Environments – Questionnaire 4

• At what levels, can we set up attributes for the HTTP access logs.

  You can set the attributes that define the behavior of HTTP access logs for each server instance or for each virtual host that you define
  

• On what factors, do weblogic server rotate the logs.

  You can rotate the log file based on either the size of the file or after a specified amount of time has passed
  

• Can we add custom fields to the common log format.

  No. It can be added to the Extended Log format.
  

• How do we add custom field to Extended Log format

  To create a custom field you identify the field in the ELF log file using the Fields directive and then you create a matching Java class that generates the desired output. You can create a separate Java class for each field, or the Java class can output multiple fields.
  

• What are the attributes set to prevent Denial of Service attacks.

  You can set three attributes in WebLogic Server that help prevent this type of attack.
           PostTimeoutSecs
           MaxPostTimeSecs
           MaxPostSize

• What is the HTTP Status code returned by server, when Server is configured for Denial of Attacks.

  An HTTP error code 413 (Request Entity Too Large) is sent back to the client.
  

• When is HTTP Tunneling useful

  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.
  

• What is the default status of HTTP Tunneling

  HTTP tunneling is disabled by default.
  

• What is the criteria with respect to protocols, to use HTTP Tunneling

  The server must also support both the HTTP and T3 protocols in order to use HTTP tunneling
  

• How to make use of HTTP Tunneling to connect to weblogic server from the client

  When your client requests a connection with WebLogic Server, all you need to do in order to use HTTP tunneling is specify the HTTP protocol in the URL. For example:
  Hashtable env = new Hashtable();
  env.put(Context.PROVIDER_URL, “http://wlhost:80“);
  Context ctx = new InitialContext(env);
  

• In what Operating Systems, can we set the weblogic server to use Native IO for serving static files

  Applicable to Windows Only.
  

• What is the advantage of setting to use Native IO for serving static files.

  Using native I/O can provide performance improvements when serving larger static files.
  

• How do you set Native IO

  weblogic.http.nativeIOEnabled tag is added in web.xml file
  

• What is weblogic Persistent Store

  The persistent store provides a built-in, high-performance storage solution for WebLogic Server subsystems and services that require persistence
  

• What are the different weblogic subsystems that can use Peristent Store
  • Diagnostic Service
    
  • JMS Messages
    
  • JMS Paging Store
    
  • JTA Transaction Lob(TLOG)
    
  • Path Service
    
  • Store and Forward (SAF) Service Agents
    
  • Web Services
    
  • EJB Timer Services
    
• Can the Custom Share be Shared by multiple Subsystems. If so, whats the contraint. If not, why

  The Default and custom stores are shareable by multiple subsystems, as long as they are all targeted to the same server instance or migratable target.
  

• What type of persistent store can be the Default Persistent Store.

  The default persistent store can only be a file store. Therefore, a JDBC store cannot be used as a default persistent store.
  

• What is special about Migratable JMS-related Services, in relation with Persitent Stores.

  Migratable JMS-related services cannot use the default file store, so you must configure a custom file store or JDBC store and target it to the same migratable target as the JMS server, SAF agent, or path service associated with the store.
  

• What is the Default Store location

  The default store maintains its data in a data\store\default directory inside the servername subdirectory of a domain’s root directory
  

• Can default Store type be changed. If so, how.

   

• When is it advisable to go for the Persistent Store

  Place a file store’s files on a particular device.
  Use a JDBC store rather than a file store for a particular server instance.
  Allow all physical stores in a cluster to share the same logical name.
  Logically separate different services to use different files or tables.
  Migratable JMS-related services cannot use the default persistent store, so you must configure a custom store and target it to the same migratable target as the migratable JMS service
  

• What are the different methods of creating Persistent Store
  • Use the Administration Console.
    
  • Directly edit the configuration file (config.xml).
    
  • Use Weblogic JMX
    
  • Use WLST
    
  • Use Weblogic Configuration Wizard
    
• What is the use of SynchronousWritePolicy of Persistent Store and what is the Oracle Recommendation on the value.

  The Synchronous Write Policy determines the behavior of the write operation of the file store. For most scenarios, Oracle recommends using the Direct-Write-With-Cache policy.
  

• Explain Direct-Write-With-Cache Policy

  When this policy is selected, WebLogic Server writes synchronously to a primary set of files in the location defined by the Directory attribute of the file store configuration using a native I/O wlfileio driver. WebLogic Server also asynchronously writes to a corresponding cache file in the location defined by the CacheDirectory attribute of the file store configuration, which is done implicitly by using OS memory caching the cache file blocks as output buffers for the primary data file.
  

  The cache files are used for performance optimizations at runtime and boot time and for recovery. This combination of direct writing with a native file driver and the use of corresponding cache files typically provides the best overall performance with the most safe disk writes.
  

• What is the directory of the file store configuration that is important for Direct-Write-With-Cache Policy

  The true persistent storage for messages is defined by the Directory attribute of the file store configuration.
  

Configure Server Environments – Questionnaire 3

• What is the use of Administration Port

  Administration port is used by each Managed Server in the domain exclusively for communication with the domain Administration Server.
  

• List down Administration Port capabilities
  • Start a server in standby state
    
  • Separate administration traffic from application traffic in your domain.
    
  • Administer a deadlocked server instance using WLST.

   

• Managed server has been configured for very first time. Managed server don’t support SSL. Administration Port is enabled. Will the newly configured managed server be able to start. If so, how. If not, why

  Managed Servers that do not support SSL cannot connect with the Administration Server during startup—you
  

  will have to disable the administration port in order to configure them.
  

• Managed server has been configured for very first time. Managed server don’t support SSL. Administration Port is enabled. In order to start the managed server, can I disable the Admin port for this managed server and start the instance.

  You can change an individual Managed Server administration port number, but you cannot enable or disable the administration port for an individual Managed Server.
  

• What is the use of default listen port or default SSL listen port

  It is required in the event that the server cannot bind to its configured administration port.
  

• What are the changes to be made to the Node manager startup arguments, after enabling the administration port.

  If you use Node Manager for restarting the Managed Servers, it is not necessary to modify startup settings or arguments for the Managed Servers. Node Manager automatically obtains and uses the correct URL to start a Managed Server.
  

• How do we disable the hostname verification between the URL and the hostname in the SSL Certificate.

  If the hostname in the URL is not identical to the hostname in the Administration Server’s certificate, disable hostname verification in the command line or start script, as shown below:
  -Dweblogic.security.SSL.ignoreHostnameVerification =true
  

• How do you bind the managed server to an administrative channel during reboot.

  To allow a Managed Server to bind to an administrative channel during reboot, use the following command-line option:
  -Dweblogic.admin.ListenAddress=<addr>
  

• How do you configure Custom Administrative Channels

  To configure a custom channel for administrative traffic, configure the channel, and select “admin” as the channel protocol.
  

• Can the Administration traffic be separated from cluster communication traffic

  WebLogic Server allows you to create network channels to handle administration traffic or communications between clusters.

• When is it useful to create separate network channels to handle administration traffic or communications between clusters.

  This can be useful in the following situations:
  ■ Internal administration traffic needs to occur over a secure connection, separate from other network traffic.
  ■ Other types of network traffic, for example replication data, need to occur over a separate network connection.
  ■ Certain types of network traffic need to be monitored.
  

• For what type of Server to Server traffic, internal channels can be created

  Within a cluster, internal channels can be created to handle to the following types of server-to-server connections:
  ■ Multicast traffic
  ■ Replication traffic
  ■ Administration traffic
  

• What will be the status of requests when you shutdown the channel

  When you shutdown a channel while the server is running, the server does not attempt to gracefully terminate any work in progress.
  

• What are the restrictions for Channel Naming

  WebLogic Server uses the internal channel names .WLDefaultChannel and .WLDefaultAdminChannel and reserves the .WL prefix for channel names. Do not begin the name of a custom channel with the string .WL.
  

• What happens if custom channel specifies the same port as Managed Server’s default port.

  If the custom channel specifies the same port as a Managed Server’s default port, the custom channel and the Managed Server’s default channel will each try to bind to the same port, and you will be unable to start the Managed Server.
  

• When we want to use a channel in the cluster, do we need to configure it in each managed server in the cluster.

  For each channel you want to use in the cluster, configure the channel identically, including its name, on each Managed Server in the cluster.
  

• What is Replication Channel

  A replication channel is a network channel that is designated to transfer replication information between clusters.
  

• When do the default Replication Channel being used.

  If a replication channel is not explicitly defined, WebLogic Server uses a default network channel to communicate replication information.
  

• When weblogic Server uses default network channel for Replication, can this communication be SSL encrypted. If so, what are its implications. If not, why

  When WebLogic Server uses a default network channel as the replication channel, it does not use SSL encryption by default. You can enable SSL encryption using the secureReplicationEnabled attribute of the ClusterMBean.
  Enabling SSL encryption can have a direct impact on clustered application throughput as session replication is blocking by design. in other words, no response is sent to the client until replication is completed. You should consider this when deciding to enable SSL on the replication channel.
  

• What is the protocol being used, if replication channel is explicitly defined.

  If a replication channel is explicitly defined, the channel’s protocol is used to transmit replication traffic.
  

• What is the impact of setting up the Packet Size to different instances of weblogic server

  MTUSize attribute in the Server element of config.xml sets the maximum size for packets sent using the associated network card. It affects the instances where the same NIC card address is used.
  

• How can custom channel be assigned to an EJB

  You can assign a custom channel to an EJB. After you configure a custom channel, assign it to an EJB using the network-access-point element in weblogic-ejb-jar.xml.
  

• Can the Weblogic server listen on port 80, even though weblogic user is not a previliged user. If so, how. If not, why

  By setting the weblogic.system.enableSetUID property (and, if desired, the weblogic.system.enableSetGID property) to true, you enable an internal process by which WebLogic Server switches its UNIX user ID (UID) after it binds to port 80.
  

• What are the most common parameters that can be set up to each virtual host separately.

  For each virtual host that you define you can also separately define HTTP parameters and HTTP access logs.
  You can also designate a default Web Application for each virtual host
  

• What are the two different formats Weblogic server uses to log HTTP transactions

  WebLogic Server can keep a log of all HTTP transactions in a text file, in either common log format or extended log format.