J2EE Connectors

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					   J2EE
 Connector
Architecture
                                       Outline

• Connector Overview
   – Goals
   – J2EE Integration
• Common Client Interface (CCI)
   – Object Model
   – Example Usage
• System Contracts
   – Connection Pooling
   – Transactions
   – Security
• Deployment (.rar files)
• Future Direction


          Copyright                J2EE Connector Architecture
          Object Computing, Inc.
                                             (2)
                                   Connector Goals

• Provide standardized interfaces to Enterprise Information Systems
  (EIS)
   – Mainframe Transaction Processing (TPs) - CICS, Tuxedo
   – Enterprise Resource Planning (ERP) - PeopleSoft, SAP
   – Database Systems - JDBC, LDAP
• The Resource Adapter (RA) is a system-level software driver used
  to connect to an EIS
• The resource adapter may be utilized in a managed (application
  server) or non-managed environment
   – Primary goal is to smoothly integrate J2EE components and EIS systems
   – Support general capabilities of J2EE 1.3 application servers
       » Scalability (typically via Pooling, Lifecycle management, clustering)
       » Distributed Transactions
       » Security


          Copyright                    J2EE Connector Architecture
          Object Computing, Inc.
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                                        Contracts

• A resource adapter supports three types of contracts
   – The Application contract (may support CCI)
       » A JCA Resource Adapter is not required to support any specific application contract (e.g.
         future versions of JDBC)
   – The JCA System contracts
       » Connection Management
       » Transaction Management
       » Security Management
   – The EIS protocol contract (typically proprietary)
• The packaging of the adapter could also be considered a contract
   – Follows J2EE jar and deployment descriptor pattern




           Copyright                   J2EE Connector Architecture
           Object Computing, Inc.
                                                 (4)
              High-Level Connector Architecture


                         Container-Component
App Server                     Contract                      Application
                                                             Component


                                                                    Application Contract
Connection                                                            (may be CCI)
 Manager

                                JCA                         JCA Resource
    Transaction                System                         Adapter
     Manager                  Contracts
                                                                    EIS-Specific
                                                                      Protocol
           Security
           Manager

                                                               EIS



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                                    Application Contracts

• The application contracts apply to user interaction with the
  Resource Adapter
   – Whether from a J2EE component or standalone
• Ideally, the contracts extend standard interfaces detailed in the
  Connector Specification
   – Called the “Common Client Interface” or CCI
   – Interfaces provide standardization for:
       »   obtaining connections
       »   submitting synchronous requests for record-based data
       »   querying metadata
       »   controlling local transactions

• Support for CCI is NOT required
   – Vendor may provide totally proprietary interfaces



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           Object Computing, Inc.
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                      Common Client Interface and JDBC

• Like JDBC, CCI deals with record-oriented queries and follows a
  similar usage pattern

  Function                        JDBC (java.sql)                       CCI (javax.resource.cci)
                                                                        ConnectionFactory +
  Create Connection               javax.sql.DataSource                  ConnectionSpec
  Create Commands                 Connection                            Connection

  Format Commands                 Statement                             Interaction + InteractionSpec
  Obtain Results                  ResultSet                             RecordFactory & Records




         Copyright                        J2EE Connector Architecture
         Object Computing, Inc.
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                                                 “Spec” classes

• CCI includes the ConnectionSpec to pass arbitrary information
   – An empty interface
   – Implementation defines properties following JavaBean conventions (get/set)
   – Standard Properties: UserName, Password
• InteractionSpec
   – connection.getInteraction() takes an InteractionSpec argument
   – Also a JavaBean with standard properties public interface javax.resource.cci.InteractionSpec
        »   FunctionName                                                extends Serializable {
        »   ExecutionTimeout                                              public static final int SYNC_SEND = 0;
                                                                          public static final int SYNC_SEND_RECEIVE = 1;
        »   FetchSize                                                     public static final int SYNC_RECEIVE = 2;
        »   InteractionVerb - synchronous actions                       }
               •   SYNC_SEND
               •   SYNC_SEND_RECEIVE (default)
               •   SYNC_RECEIVE

        » ResultSetType - java.sql.ResultSet (FORWARD, SCROLL_SENSITIVE)
        » ResultSetConcurrency - java.sql.ResultSet (READ_ONLY, UPDATABLE)
   – May be bound in JNDI as a resource environment reference (like JMS Topics)

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            Object Computing, Inc.
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                                     Records

• An Interaction uses Record objects to qualify invocations and
  receive data in response




         Copyright                J2EE Connector Architecture
         Object Computing, Inc.
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                                    Records (cont’d)

• Records may be created through a provided implementation of the
  RecordFactory interface
   – The MappedRecord is a Map
   – The IndexedRecord is a List
   – Either may contain hierarchical structures of Records
• The create() methods of the factory take a recordName as an
  argument
   – The factory will utilize this name to reference meta information related to the
     construction of the record type
• The resource adapter may include additional means to create custom
  records




           Copyright                  J2EE Connector Architecture
           Object Computing, Inc.
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                                        ResultSet

• The CCI ResultSet extends the JDBC ResultSet
   – Provides similar support for scrolling, type mapping, updatability
• It may not support more advanced JDBC types
   – Blob, Clob, Array, Ref, Distinct, Struct, customized mapping
• java.sql.ResultSetMetaData is reused
   – Query column name, type, etc.
• ResultSetInfo provides information on the supported ResultSet
  functionality
   – e.g. visibility of updates and inserts




           Copyright                   J2EE Connector Architecture
           Object Computing, Inc.
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                          CCI Example - CICS Connector
// STANDALONE
//create and set values for a managed connection factory for EPI
EPIManagedConnectionFactory mcf =new
    EPIManagedConnectionFactory();
cf.setConnectionURL("tcp://gunner.almaden.ibm.com");
cf.setServerName("SCSCPAA6");
ConnectionFactory
    cxf=(ConnectionFactory)mcf.createConnectionFactory();

// or J2EE (using Environment Naming Context)
InitialContext ctx = new InitialContext();
ConnectionFactory cxf =
     (ConnectionFactory)ctx.lookup(“java:comp/env/jca/myConnector”);

//create a connection object                                            May pass
Connection connection =cxf.getConnection();                          ConnectionSpec to
                                                                      define identity,
//create an interaction with CICS to start transaction EPIP            context, etc.
Interaction interaction =connection.createInteraction();




        Copyright                      J2EE Connector Architecture
        Object Computing, Inc.
                                                 (12)
                                CCI Example - CICS Connector

// Implements InteractionSpec
EPIInteractionSpec iSpec =new EPIInteractionSpec();
iSpec.setFunctionName("EPIP"); // well-known property
iSpec.setAID(AIDKey.enter);       // vendor-specific property
iSpec.setInteractionVerb(InteractionSpec.SYNC_SEND_RECEIVE); // default

// Create a record to store the response from CICS - implements Record
// Can create records in this way or through RecordFactory implementations
// obtained via ConnectionFactory.getRecordFactory()
EPIScreenRecord screen =new EPIScreenRecordImpl();

// execute w/ InteractionSpec, InputRecord, OutputRecord
boolean rc =interaction.execute(iSpec,null,screen);

//close the interaction and connection
interaction.close();
connection.close();




              Copyright                    J2EE Connector Architecture
              Object Computing, Inc.
                                                     (13)
                                   Connection Management

• The connection management contract allows the resource adapter to
  leverage application server support for connection pooling
   – May manage their own pools in a non-managed environment
• Application component (EJB, servlet, client) looks up a Connection
  Factory in JNDI using the Environment Naming Context (ENC)
• Component requests a Connection Handle - possibly passing
  additional information
         import javax.resource.cci.ConnectionFactory;
         import javax.resource.cci.ConnectionFactory;
         import javax.naming.InitialContext;
         ...
         InitialContext ctx = new InitialContext();
         ConnectionFactory fcty = (ConnectionFactory)ctx.lookup(“java:comp/env/eis/myEIS”);
         Connection conn = fcty.getConnection(new MyEISConnectionSpec(data));


           Note that this example assumes support of CCI
          Copyright                      J2EE Connector Architecture
          Object Computing, Inc.
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                           Connection Management (cont’d)

• Multiple connection handles may refer to the same underlying
  ManagedConnection (physical connection)
• The app server will examine its pool of connections and determine a
  subset which could match the request (<res-sharing-scope>)
• The app server calls matchManagedConnection() on the resource
  adapter with parameters:
   – Information passed to getConnection() (via a ConnectionSpec if CCI)
   – Security information for the current principal (javax.security.auth.Subject)
   – A subset of active connections (based on app server logic)
• If none of the candidates match, the app server will request a new
  connection
• Note that over time the app server may associate many different
  connection handles with a single ManagedConnection (@see
  associateConnection())
           Copyright                 J2EE Connector Architecture
           Object Computing, Inc.
                                               (15)
                          Connection Management Interaction




RA must provide
for non-managed




             Copyright                J2EE Connector Architecture
             Object Computing, Inc.
                                                (16)
                         Transaction Management Contract

• J2EE distinguishes two types of transactions and contracts for each
• A transaction controlled external to the resource manager is an XA
  or JTA transaction
   – The resource manager may only support one-phase commit of XA transactions
• A transaction managed internal to the resource manager is a local
  transaction
• An adapter may support either, both, or neither (<transaction-
  support>)
            public interface javax.resource.spi.ManagedConnection {
            …
             javax.transaction.xa.XAResource getXAResource() throws ResourceException;
             javax.resource.spi.LocalTransaction getLocalTransaction() throws ResourceException;
            ...
            }



          Copyright                       J2EE Connector Architecture
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                                   Transaction Management

• Many scenarios are problematic if all resource managers do not
  support XA transactions with 2PC
   – The same thread of execution (involving one or more app components) may only
     utilize a single non-XA RA
   – In general, use of non-XA and XA capable RAs may not be mixed in the same thread
     of execution
   – Local transactions may not span container boundaries (J2EE 1.3 spec)
• But... higher performance is attained through the use of only local
  transactions
   – But how does server know a priori what resource managers will be involved in a
     transaction ?
   – Some advantage may be achieved through 1-PC optimization
   – 2PC “last resource optimization” may be provided by some app servers
• Any number of non-transactional resource managers may be mixed
  with transactional ones
          Copyright                      J2EE Connector Architecture
          Object Computing, Inc.
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                                XA Transaction Management

• XA transactions are initiated and terminated (commit or rollback) in
  two basic ways in J2EE
   – By the container based on deployment descriptor settings
   – Explicitly by component code (Using JTA UserTransaction)
• In neither case are low-level XA interfaces visible to components
• Typically, container-managed transactions are used
   – In this scenario, a transaction context is active at the time the getConnection() call is
     made (upon entry into the method implementation)
   – After the app server obtains a ManagedConnection, it gets the XAResource from the
     connection and enlists it with the transaction manager
   – The final Connection.close() causes the resource to be delisted
   – At method completion, the container completes the transaction and the transaction
     manager utilizes the two-phase commit on all previously enlisted resources




           Copyright                   J2EE Connector Architecture
           Object Computing, Inc.
                                                 (19)
                              Local Transaction Management

• Local transactions may be either container-managed or component-
  managed
   – Components manage local transactions using a RA-specific API (typically
     implementing javax.resource.cci.LocalTransaction)
   – The LocalTransaction instance is obtained from the connection
       » contains only start(), commit(), rollback()
   – In situations of component-managed local transactions the app server is notified of
     transaction events via the ConnectionEventListener



             public interface javax.resource.spi.ConnectionEventListener {
             …
              void localTransactionStarted(ConnectionEvent event);
              void localTransactionCommitted(ConnectionEvent event);
              void localTransactionRolledback(ConnectionEvent event);
             ...
             }


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                                   Security Contracts

• The application component provider has 2 options for EIS sign-on
   – Container -> Authentication details defined by the deployer
   – Application -> Passed to getConnection() by component code
   – Choice is defined in component deployment descriptor <res-auth> element
• Adapters often provide default settings in their descriptors
• Application-level authentication information is passed directly to
  the RM
   – Opaque to the connector architecture
• Container-level authentication information is one two types
   – PasswordCredential
   – GenericCredential
• The type passed to the adapter is defined by its deployment
  descriptor - <credential-interface>

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                                    Container Authentication

• JCA utilizes the JAAS APIs to pass authentication information
• The app server creates a javax.security.auth.Subject object which
  contains a single principal and an instance of the correct Credential
  type
• The Subject instance is passed to the ManagedConnectionFactory
  matchManagedConnection() or createManagedConnection()
  methods by the app server
• The app server determines the contents of the Credential based on:
   – The principal identification in effect at the time of getConnection()
        » May be different from the authenticated user (e.g. EJB 2.0 runAs)
   – <authentication-mechanism-type> element(s)
   – deployment settings for mapping of principal identifications




           Copyright                      J2EE Connector Architecture
           Object Computing, Inc.
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                            Resource Principal Identification

• The resource principal identity for the adapter-EIS communication
  may be established by the deployer in various ways:
   – Configured Identity (static)
        » Identity is defined in descriptor
   – Principal Mapping
        » Each resource has a mapping of component principal -> resource principal
   – Caller Impersonation
        » Resource principal acts on behalf of the caller principal
        » Principal delegation specific to security mechanism (e.g. Kerberos)
   – Credentials Mapping
        » The principal identity remains the same but credentials are mapped to a different
          authentication domain




           Copyright                     J2EE Connector Architecture
           Object Computing, Inc.
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                                   Caching Manager

• Current JCA architecture includes minimal contracts for a Caching
  Manager
• The caching manager registers interest in transaction events
   – Similar to the EJB SessionSynchronization interface
   – beforeCompletion() - just prior to commit()
   – afterCompletion() - notifies whether transaction committed or rolledback
• The caching manager services CCI queries and resyncs with the EIS
            when appropriate based on the above callbacks
  • Connector-based JDO implementations are Caching Managers




          Copyright                  J2EE Connector Architecture
          Object Computing, Inc.
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                                   Packaging and Deployment

• Resource adapters are packaged in jar files similar to application
  components (suffix is .rar)
• The Resource Adapter Archive contains all java and native files
  required to execute
• Also contains the RAR deployment descriptor - ra.xml
• Each application server typically provides a schema for an
  additional proprietary deployment descriptor
   – JNDI bind location
   – Details of security mapping




          Copyright                       J2EE Connector Architecture
          Object Computing, Inc.
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                      Contents of the Deployment Descriptor

• Class file identification
   – <connection-interface> and <connection-impl-class>
   – <connectionfactory-interface> and <connectionfactory-impl-class>
   – <managedconnectionfactory-class>
• Security Settings
   –   <authentication-mechanism-type>* - BasicPassword, Kerbv5, etc.
   –   <credential-interface> - PasswordCredential or GenericCredential
   –   <reauthentication-support> - Can ManagedConnections change principal ?
   –   <security-permission> - special security permissions (standard “grant” .policy syntax)
         » use privileged code blocks to exercise

• Misc
   – <license-required>
   – <config-property> - misc configuration values



            Copyright                    J2EE Connector Architecture
            Object Computing, Inc.
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                                   Future Direction

• Specification
   – Pluggability of JMS Providers
   – Thread Management Contract
       » Needed to allow asynchronous communication with EIS
       » Finally have the ability to create threads (!?)
   – CCI support requirement
   – CCI XML support
       » Metadata - Query Interactions and Record types available
       » Submit Interactions as XML

• Industry
   – Entity Bean CMP mapping to EIS ?
   – Greater variety and ease of use of EIS
   – Ability of new technologies to integrate with J2EE
       » JDO ?



          Copyright                   J2EE Connector Architecture
          Object Computing, Inc.
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                                       Vendors

• Insevo
   – CICS, IMS, JD Edwards, Baan, SAP, Siebel, PeopleSoft
   – Support CCI and XML-based interface/schema repository
   – Bi-directional communication
• Resource Adapters, Inc
   – SAP, PeopleSoft, Siebel, Oracle
   – Also support XML interaction and Bi-directional communication
• SolarMetric, PrismTech, FastObjects, Versant
   – JDO Implementations w/JCA support
• Sonic
   – Can plug RAs into SonicXQ as services




           Copyright                J2EE Connector Architecture
           Object Computing, Inc.
                                              (28)

				
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