Examples of org.jbpm.env.Environment

org.jbpm.env.Environment
maintains contextual information for a thread in a set of {@link Context}s.
Introduction

Objects have different lifecycles and different context's (aka scopes). An environment provides the structure to easily manage objects with different contexts.

Examples of contexts are:
- application: The application context is used to store e.g. data sources, session factories and other static resources needed by an application. The application context lives for the complete duration of the {@link EnvironmentFactory}. So if the {@link EnvironmentFactory} is maintained in a static member field, the application context lives for the duration of the application. The same application context is shared for all the Environments produced by one EnvironmentFactory.
- block: The block context is used for e.g. a transaction and transactional resources, user authentication. In combination with a {@link WireContext}, this results in an efficient and configurable use of transactional resources that need to be lazily initialized.
- The environment can accomodate other contexts as well. They can be added and removed dynamically. Examples of other potential contexts are web-request, web-session, web-application, business processDefinition, job, ...
An environment is typically installed like this
static EnvironmentFactory environmentFactory = new DefaultEnvironmentFactory(); ... Environment environment = environmentFactory.openEnvironment(); try { ... everything available in this block ... } finally { environment.close(); }

Purpose

The first purpose of the environment is to separate the application from the environment. Standard Java and Enterprise Java are quite different and an environment abstraction like this allows for the development of applications that can run in both Standard and Enterprise environments. Also test environments are easier to tweak this way.

A second purpose of the environment is to enable specific to global searching of resources. E.g. you could search for an 'adminEmailAddress' in the contexts 'processDefinition-execution', 'processDefinition-definition' and 'application' in the given order. That way, a global adminEmailAddress can be specified in the application context and it can be refined in more specific contexts processDefinition-definition or processDefinition-execution.

Search order

To find an object in the environment, a searchOrder can be specified. A search order is an sequence that specifies the order in which the contexts should be searched.

The default search order is the inverse sequence of how the contexts are added to the environment. This is because in general, we can assume that the more recent a context was added, the more specific it is.

Transaction, username and classloader

Three objects are used so frequently in an environment that they get special treatment:
- Transaction: an abstraction for marking a transaction with setRollbackOnly.
- Classloader: the current class loader.
- Username: the name of the currently authenticated user.
For these special properties, setters are also available. That is to support programmatic injection into the environment. Alternatively, they can be configured in one of the contexts.
@see EnvironmentFactory @author Tom Baeyens

  public CommentImpl(String message, Execution execution) {
    this.message = message;
    this.execution = (ExecutionImpl) execution;
    this.time = Clock.getCurrentTime();
    
    Environment environment = Environment.getCurrent();
    if (environment!=null) {
      this.actorId = environment.getUserId();
    }
  }

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    if (value==null) {
      log.finest("creating null variable for "+key);
      variable = new NullVariable();
    } else {
    
      Environment environment = Environment.getCurrent();
      if (environment!=null) {
        VariableTypeResolver variableTypeResolver = environment.get(VariableTypeResolver.class);
        if (variableTypeResolver!=null) {
          variable = variableTypeResolver.createVariable(key, value, this);
        }
      }

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  private static final long serialVersionUID = 1L;


  public Object construct(WireContext wireContext) {
    EnvironmentInterceptor environmentInterceptor = new EnvironmentInterceptor();
    Environment environment = wireContext.getEnvironment();
    EnvironmentFactory environmentFactory = environment.getEnvironmentFactory();
    environmentInterceptor.setEnvironmentFactory(environmentFactory);
    return environmentInterceptor;
  }

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  // close ////////////////////////////////////////////////////////////////////


  public void close() {
    defaultEnvironmentFactory.applicationWireContext.fire(DefaultEnvironment.EVENT_CLOSEENVIRONMENT, this);
    
    Environment popped = pop();
    if (this!=popped) {
      throw new PvmException("environment nesting problem");
    }


    Context context = getBlockContext();

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  public void testPvmDbSession() {
    EnvironmentFactory environmentFactory = EnvironmentFactory.parseResource(
        "org/jbpm/examples/ch10/jbpm.environment.xml"
    );
    
    Environment environment = environmentFactory.openEnvironment();
    try {
      PvmDbSession pvmDbSession = environment.get(PvmDbSession.class);
      
      ProcessDefinition processDefinition = ProcessFactory.build("persited process")
      .done();
      
      pvmDbSession.save(processDefinition);
      
    } finally {
      environment.close();
    }
  }

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 * @author Tom Baeyens
 */
public class AuthorizationInterceptor extends Interceptor {


  public Object execute(Command command) {
    Environment environment = Environment.getCurrent();
    if (environment==null) {
      throw new PvmException("no environment for verifying authorization");
    }
    AuthorizationSession authorizationSession = environment.get(AuthorizationSession.class);
    if (authorizationSession==null) {
      throw new PvmException("no AuthorizationSession in environment for verifying authorization");
    }
    authorizationSession.checkPermission(command, environment);
    // if the authorization check succeeded, proceed

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  }


  protected ClobStrategy getClobStrategy() {
    ClobStrategy clobStrategy = null;
    
    Environment environment = Environment.getCurrent();
    if (environment!=null) {
      clobStrategy = (ClobStrategy) environment.get(CLOB_STRATEGY_ENV_KEY);
    }


    if (clobStrategy==null) {
      clobStrategy = DEFAULT_CLOB_STRATEGY;
    }

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  }


  protected BlobStrategy getBlobStrategy() {
    BlobStrategy blobStrategy = null;
    
    Environment environment = Environment.getCurrent();
    if (environment!=null) {
      blobStrategy = (BlobStrategy) environment.get(BLOB_STRATEGY_ENV_KEY);
    }


    if (blobStrategy==null) {
      blobStrategy = DEFAULT_BLOB_STRATEGY;
    }

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 * @author Tom Baeyens
 */
public class TransactionInterceptor extends Interceptor {


  public Object execute(Command command) {
    Environment environment = Environment.getCurrent();
    if (environment==null) {
      throw new PvmException("no environment for verifying authorization");
    }
    Transaction transaction = environment.getTransaction();
    if (transaction==null) {
      throw new PvmException("no transaction in environment");
    }
    try {
      return next.execute(command);

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public class EnvironmentInterceptor extends Interceptor {


  protected EnvironmentFactory environmentFactory;


  public Object execute(Command command) {
    Environment environment = environmentFactory.openEnvironment();
    try {
      return next.execute(command);
      
    } finally {
      environment.close();
    }
  }

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Related Classes of org.jbpm.env.Environment

org.jbpm.client.impl.AsyncCommandService

org.jbpm.client.impl.AuthorizationInterceptor

org.jbpm.client.impl.EnvironmentInterceptor

org.jbpm.client.impl.StandardCommandService

org.jbpm.client.impl.TransactionInterceptor

org.jbpm.env.impl.DefaultEnvironment

org.jbpm.env.session.timer.MemoryTimerSession$ExecutionTask

org.jbpm.examples.ch09._01_EnvironmentTest

org.jbpm.examples.ch10.PvmDbSessionTest

org.jbpm.lob.Blob

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Examples of org.jbpm.env.Environment

Introduction

Purpose

Search order

Transaction, username and classloader

Related Classes of org.jbpm.env.Environment