com.ibm.bpm.context

Interface ContextService



  • public interface ContextService
    The ContextService interface represents the programming model for the context service in BPM. The BPM context service provides the ability to access and modify protocol headers and execution context.It also propagates the execution context to downstream components.

    The following code is used to locate context service:

            ContextService contextService = (ContextService) ServiceManager.INSTANCE
                    .locateService("com/ibm/bpm/context/ContextService");
            
    The following features are supported:

    The above two features can be accessed by ContextObject too.

    The data which is set into the execution context by context service can be propagated across modules. Assuming there are two modules, Module A and Module B. Component A is in module A, component B is in module B, and, component A calls component B. In component A, the context data can be set like this:

       //Get the HeaderInfoType from contextService
             HeaderInfoType headers = contextService.getHeaderInfo();
             if(headers == null){ //Create new HeaderInfoType if its null and you want to propagate additional properties using headers
                    headers = ContextObjectFactory.eINSTANCE.createHeaderInfoType();
             }
    
       //Propagating custom properties through headers
       //Create a new property
                    PropertyType prop = ServiceMessageObjectFactory.eINSTANCE.createPropertyType();
                    prop.setName("Name"); //Set the name of the property
                    prop.setValue("value"); //Set the value of the property
                    prop.setPropertyType("java.lang.String"); //Set the type the property
    
                    List properties = headers.getProperties();
                properties.add(prop); //Add the property to the list of header properties
    
       // Set header info back to the current execution context.
       contextService.setHeaderInfo(headers);
    
       //Propagating custom data through UserDefinedContext
       // Get user defined context in current execution context
       UserDefinedContextType userDefinedContext = contextService.getUserDefinedContext();
       if(userDefinedContext == null){ // create a new context if context is null
            userDefinedContext = ContextObjectFactory.eINSTANCE.createUserDefinedContextType();
       }
       // Modifying the userDefinedContext
    
       //Create a new property with the data that needs to be propagated
             ComplexPropertyType customerData = ServiceMessageObjectFactory.eINSTANCE.createComplexPropertyType();
             customerData.setName("customer"); //Set the name of the property
    
             //The value of the data must be of type DataObject.
             //Use BusinessObject Factory service to create a DataObject
             BOFactory boFactory = (BOFactory) ServiceManager.INSTANCE.locateService("com/ibm/websphere/bo/BOFactory");
             //Pass the targetNameSpace of the business object and the ComplextTypeName
             DataObject dataObject = boFactory.create("http://www.ibm.com/xmlns/customer", "Customer");
    
             customerData.setValue(dataObject);//Set the value on the property
    
             //Get the UserContextType from UserDefinedContextType
             UserContextType userContext = userDefinedContext.getUserContext();
             if(userContext == null) //If the userContext is null, create a new instance and set in on the userDefinedContext
             {
                    userContext = ServiceMessageObjectFactory.eINSTANCE.createUserContextType();
                    userDefinedContext.setUserContext(userContext);
             }
             //Add the property to the userContext
             userContext.getEntries().add(customerData);
    
       // Set user defined context back to the current execution context.
       contextService.setUserDefinedContext(userDefinedContext);
    
       
    The context data will be propagated from component A to component B.

    In component B, the context data can be accessed like below:

    
       //Getting headers data
       HeaderInfoType headers = contextService.getHeaderInfo();
       //Retrieving the property
       if(headers != null)
             {
                    List headerProperties = headers.getProperties();
                    if(headerProperties !=null)
                    {
                            for(Iterator i = headerProperties.iterator(); i.hasNext();){
                                    PropertyType p = i.next();
                                    if(p.getName().equals("Name")){ //Check for the name of the property or directly get the property based on the index in which it was stored
                                            p.getValue();
                                            return;
                                    }
                            }
                    }
             }
    
    
             //Reading protocol specific headers
             //Reading http protocol headers
             HTTPHeaderType httpHeader = headers.getHTTPHeader();
             HTTPControl control = httpHeader.getControl();
             int contentLength = control.getContentLength();
       String method = control.getMethod();
    
       //Getting data from user defined context object
       UserDefinedContextType userDefinedContext = contextService.getUserDefinedContext();
       if(userDefinedContext != null)
       {
            List properties = userDefinedContext.getUserContext().getEntries();
                for (Iterator userContextProperties = properties.iterator(); userContextProperties.hasNext();)
                    {
                            ComplexPropertyType p = userContextProperties.next();
                            if(p.getName().equals("customer")){ //Check for the name of the property or directly get the property based on the index in which it was stored
                                    p.getValue();
                                    return;
                            }
                    }
             }
    
       

    Context access and propagation can make the business logic more clean, but setting large data in execution context or headers would impact the performance. Because once the data is set to current execution context, it will be propagated to downstream components. So, it is recommended to not put large data into current execution context.

    The ContextService API should not be used within a mediation flow. The SMO API should be used instead.

    com.ibm.websphere.sibx.smobo.ContextType context = smo.getContext();
    If the updated context data is not set back by setHeaderInfo, setUserDefinedContext, or setContextObject, the context service will NOT propagate the updated data to the downstream. Refer to Service Message Object documentation for more details on HeaderInfoType and UserDefinedContext APIs.
    • Method Detail

      • getHeaderInfo

        HeaderInfoType getHeaderInfo()
        Get the protocol headers in the current execution context

        The protocol headers type is represented by HeaderInfoType.

        Returns:
        the protocol header's information in current execution context
        See Also:
        HeaderInfoType
      • setHeaderInfo

        void setHeaderInfo(HeaderInfoType headerInfo)
        Set the protocol headers to the current execution context.

        If the input headers value is null, the protocol headers in current execution context will be removed.

        The context service will not propagate the updated context data if it is not set to current execution context.

        Parameters:
        headerInfo - the protocol header's information.
        See Also:
        HeaderInfoType
      • setUserDefinedContext

        void setUserDefinedContext(UserDefinedContextType userDefinedContext)
        Set user defined context data to the current execution context.

        If the input context value is null, the user defined context data in the current context will be removed.

        The context service will not propagate the context data if it is not set to current execution context.

        Parameters:
        userDefinedContext - the user defined context data.
        See Also:
        UserDefinedContextType
      • getContextObject

        ContextObject getContextObject()
        Get context object from current execution context.

        ContextObject is the container of header info and user defined context. It provides xpath like style to access and modify context data. For example:

                ContextObject contextObject = contextService.getContextObject();
                HeaderInfoType headers = contextObject.getHeaderInfo();
                UserDefinedContextType userDefinedContext = contextObject.getUserDefinedContext();
        
                
        Returns:
        context object
        See Also:
        ContextObject
      • setContextObject

        void setContextObject(ContextObject contextObject)
        Set context object to current execution context.

        If the modified context object is not set to current execution context, context service will not propagate the modified data. So, after the context object is modified, please set it back to current execution context:

                // get context object
                ContextObject contextObject = contextService.getContextObject();
                // Retrieve HeaderInfoType/UserDefinedCotextType objects and modify the data like specified above
                ... ...
                // Set the modified context object back to current execution context
                contextService.setContextObject(contextObject);
         
        Parameters:
        contextObject - the context object.
        See Also:
        ContextObject
IBM Business Process ManagerTM
Release 8