Working with Context Parameters

You can retrieve a context parameter from a request or from a response, and set a context parameter in a request or a response.

Retrieving a Context Parameter from a Request

Procedure

  1. Retrieve the request context: 
    import com.tibco.amf.platform.runtime.extension.context.RequestContext;
RequestContext requestContext = 
 (RequestContext)componentContext.getRequestContext();
  2. Retrieve the parameter from the request context: 
    requestContext.getParameter(parameterName, Type.class);

    where Type can take the values String, Integer, Long, Boolean, Map, QName, and URI.

Setting a Context Parameter in a Request

Procedure

  1. Create a mutable request context: 
    import com.tibco.amf.platform.runtime.extension.context.MutableRequestContext;
MutableRequestContext mutableRequestContext = componentContext.
 createMutableRequestContext();
  2. Set a parameter on the mutable request context: 
    mutableRequestContext.setParameter(parameterName, Type.class, 
  parameterValue);
  3. Set the request context on the component's context to the mutable request context: 
    componentContext.setRequestContext(mutableRequestContext);
  4. Invoke a reference.
    Note:

    The componentContext.getRequestContext() function returns the request context that corresponds to the last remotable service invocation whereas componentContext.setContext() assigns the context that gets used for the next downstream service invocation. For example, in the following case, curCtx does not equal to newCtx but equals to oldCtx. 

    RequestContext oldCtx = (RequestContext)componentContext.getRequestContext();
MutableRequestContext newCtx = componentContext.createMutableRequestContext();
componentContext.setRequestContext(newCtx);
RequestContext curCtx = (RequestContext)componentContext.getRequestContext();

Retrieving a Context Parameter from a Response

Procedure

  1. Retrieve a callback context from the mutable request context: 
    import com.tibco.amf.platform.runtime.extension.context.CallbackContext;
CallbackContext callbackContext = mutableRequestContext.getCallbackContext();
  2. Retrieve a parameter from the callback context: 
    callbackContext.getParameter(parameterName, Type.class);

Setting a Context Parameter in a Response

Procedure

  1. Retrieve a mutable callback context from the original request context: 
    import com.tibco.amf.platform.runtime.extension.context.MutableCallbackContext;
MutableCallbackContext mutableCallbackContext = (MutableCallbackContext)requestContext.
  getCallbackContext();
  2. Set a parameter on the mutable callback context: 
    mutableCallbackContext.setParameter(parameterName, 
  Type.class, parameterValue);

Distributed File System Example

A distributed file system component manages files based on the host address of the machine on which the file was created. The address is tracked in a context parameter named httpHost:


The file system component is invoked by SOAP clients through a service with a SOAP binding and by a web application component.

  • If a request comes through the SOAP binding, the context parameter is mapped to the TCP remote host header by the SOAP binding:

  • If the request originates from the web application, the parameter value is retrieved from the HTTP request and manually set by the servlet implementing the web application component: 
    String host = req.getRemoteHost();
MutableRequestContext mutableRequestContext = 
 componentContext.createMutableRequestContext(); 
mutableRequestContext.setParameter("httpHost", String.class, host);
componentContext.setRequestContext(mutableRequestContext);
The file system component retrieves the value of the context parameter as follows: 
RequestContext requestContext = componentContext.getRequestContext();
String host requestContext.getParameter("httpHost", String.class);

Dynamic Binding Example

Application logic can depend on the value of the application and service name. In particular, the application logic may be used to dynamically determine the target of a reference invocation (also referred to as wire by implementation) in a mediation flow. The following example illustrates how to retrieve the application and service name in a Java component that invokes a mediation component service, and set context parameters with that data: 
String appName = componentContext.getApplicationName();
String svcname = componentContext.getRequestContext().getServiceName();	
MutableRequestContext mutableRequestContext = 
 componentContext.createMutableRequestContext();
mutableRequestContext.setParameter("ServiceName", java.lang.String.class, 
 svcname);
mutableRequestContext.setParameter("ApplicationName", 
 java.lang.String.class, appName);
componentContext.setRequestContext(mutableRequestContext);
The context parameters are then mapped in the mediation flow's Set Dynamic Reference task property sheet as follows: