{"id":5358,"date":"2012-07-19T20:44:21","date_gmt":"2012-07-20T01:44:21","guid":{"rendered":"http:\/\/jianmingli.com\/wp\/?p=5358"},"modified":"2012-08-25T22:57:43","modified_gmt":"2012-08-26T03:57:43","slug":"1z0-102-introduction-to-clustering","status":"publish","type":"post","link":"https:\/\/jianmingli.com\/wp\/?p=5358","title":{"rendered":"Introduction to WebLogic 11g Clustering"},"content":{"rendered":"
\n

Contents<\/h2>\n
    \n\t
  1. \n\t\tDesribe a WebLogic Server cluster<\/a>\n\t\t
      \n\t\t\t
    1. \n\t\t\t\tWhat is a Cluster<\/a>\n\t\t\t<\/li>\n\t\t\t
    2. \n\t\t\t\tBenefits of Clustering<\/a>\n\t\t\t<\/li>\n\t\t\t
    3. \n\t\t\t\tWhat can be Clustered<\/a>\n\t\t\t<\/li>\n\t\t\t
    4. \n\t\t\t\tProxy Server<\/a>\n\t\t\t<\/li>\n\t\t<\/ol>\n\t
    5. \n\t\tCompare basic to multi-tier cluster architectures<\/a>\n\t\t
        \n\t\t\t
      1. \n\t\t\t\tBasic Cluster Architecture<\/a>\n\t\t\t<\/li>\n\t\t\t
      2. \n\t\t\t\tBasic Cluster Proxy Architecture<\/a>\n\t\t\t<\/li>\n\t\t\t
      3. \n\t\t\t\tMultitier Cluster Architecture<\/a>\n\t\t\t<\/li>\n\t\t\t
      4. \n\t\t\t\tMultitier Cluster Proxy Architecture<\/a>\n\t\t\t<\/li>\n\t\t\t
      5. \n\t\t\t\tProxy Plug-ins<\/a>\n\t\t\t<\/li>\n\t\t\t
      6. \n\t\t\t\tHttpClusterServlet<\/a>\n\t\t\t<\/li>\n\t\t<\/ol>\n\t
      7. \n\t\tDescribe cluster communication (heartbeats, peer-to-peer)<\/a>\n\t<\/li>\n<\/ol>\n<\/ol>\n<\/div>\n
         <\/div>\n

        << Previous<\/a><\/p>\n

        Desribe a WebLogic Server cluster<\/h2><\/span>\n

        What is a Cluster<\/h3><\/span>\n

        * A cluster is a logical group of managed servers within a domain
        \n– managed servers can reside on different machine
        \n– a cluster can not span across more than one domain
        \n* Provide failover and high availability for:
        \n– whole servers
        \n– web apps and services: relies on HTTP session state replication
        \n– EJB apps: relies on replica-aware stubs, enabled in weblogic-ejb-jar.xml<\/em>
        \n– JDBC resources
        \n– JMS
        \n* Is transparent to clients<\/p>\n

        Benefits of Clustering<\/h3><\/span>\n

        * Scalability: add more server instances to support higher load
        \n* Load balancing: distribute work across members
        \n* Application failover
        \n* Availability
        \n* Migration: for pinned services and components (e.g. JTA)<\/p>\n

        What can be Clustered<\/h3><\/span>\n

        * Servlets
        \n* JSP
        \n* EJB
        \n* RMI objects
        \n* JMS destinations
        \n* JDBC connections<\/p>\n

        Proxy Server<\/h3><\/span>\n

        * Software based:
        \n– WebLogic servlet, i.e. HTTPClusterServlet<\/em>
        \n– Web server plug in, e.g. mod_wl_ohs<\/em>
        \n– third party application
        \n* Hardware based, e.g. F5 Big IP<\/p>\n

        Compare basic to multi-tier cluster architectures<\/h2><\/span>\n

        Basic Cluster Architecture<\/h3><\/span>\n
        \"\"<\/a><\/h6><\/span>\n

        * Advantages:
        \n– easy admin
        \n– flexible load balancing
        \n– robust security
        \n* Disadvantages:
        \n– EJB method calls not load balanced<\/p>\n

        Basic Cluster Proxy Architecture<\/h3><\/span>\n

        * Static content is hosted on HTTP servers<\/p>\n

        \"\"<\/a><\/h6><\/span>\n

        Multitier Cluster Architecture<\/h3><\/span>\n
        \"\"<\/a><\/h6><\/span>\n

        * Advantages:
        \n– improved load balancing (more options: presentation tier, business tier)
        \n– fewer points of failure
        \n– EJB method calls are now load balanced
        \n– improved security options (different security policy for presentation tier and business tier)
        \n* Disadvantages:
        \n– no collocation optimization (network traffic between presentation tier and business tier)
        \n– higher cost
        \n– more configuration complexity<\/p>\n

        Multitier Cluster Proxy Architecture<\/h3><\/span>\n

        * Static content is hosted on HTTP servers<\/p>\n

        \"\"<\/a><\/h6><\/span>\n

        Proxy Plug-ins<\/h3><\/span>\n

        * Delegates dynamic content requests to WLS servers
        \n* Uses round robin
        \n* Based on cookie or URL rewrite
        \n* OHS uses mod_wl_ohs<\/em> as default proxy plug-in<\/p>\n

        \"\"<\/a><\/h6><\/span>\n

        HttpClusterServlet<\/h3><\/span>\n
        \"\"<\/a><\/h6><\/span>\n

        Describe cluster communication (heartbeats, peer-to-peer)<\/h2><\/span>\n

        * Peer to peer: uses IP sockets
        \n– access pinned objects
        \n– access clustered objects that reside on a remote server instance
        \n– replicate HTTP session states and stateful session EJB states between primary and secondary server
        \n* One to many: uses Unicast (preferred) or Multicast (deprecated)
        \n– cluster wide JNDI updates<\/p>\n

        \"\"<\/a><\/h6><\/span>\n

        – cluster heartbeats<\/p>\n

        Next <\/a>>><\/p>\n

        [mv_include id=’3268′]<\/p>\n","protected":false},"excerpt":{"rendered":"

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