This topic explains how you might create your own propagation token
implementation, which is set on the running thread and propagated downstream.
About this task
The default propagation token usually is sufficient for propagating
attributes that are not user-specific. Consider writing your own implementation
if you want to accomplish one of the following tasks:
- Isolate your attributes within your own implementation.
- Serialize the information using custom serialization. You must deserialize
the bytes at the target and add that information back on the thread by plugging
in a custom login module into the inbound system login configurations. This
task also might include encryption and decryption.
To implement a custom propagation token, you must complete the following
steps:
- Write a custom implementation of the PropagationToken interface.
Many different methods are available for implementing the PropagationToken
interface. However, make sure that the methods that are required by the PropagationToken
interface and the token interface are fully implemented.
After
you implement this interface, you can place it in the profile_root/classes directory.
The profile_root variable
is the directory and name specified for the profilePath parameter at profile
creation. For more information on classes, see Creating a classes subdirectory in your profile for custom classes.
Tip: All of the
token types that are defined by the propagation framework have similar interfaces.
The token types are marker interfaces that implement the com.ibm.wsspi.security.token.Token
interface. This interface defines most of the methods. If you plan to implement
more than one token type, consider creating an abstract class that implements
the com.ibm.wsspi.security.token.Token interface. All of your token implementations,
including the propagation token, might extend the abstract class and then
most of the work is complete.
To see an implementation of the propagation
token, see Example: com.ibm.wsspi.security.token.PropagationToken implementation.
- Add and receive the custom propagation token during WebSphere Application
Server logins. This task is typically accomplished by adding a
custom login module to the various application and system login configurations.
You also can add the implementation from an application. However, to deserialize
the information, you need to plug in a custom login module, which is discussed
in Propagating a custom Java serializable object.
The WSSecurityPropagationHelper class has APIs that are used to set a propagation
token on the thread and to retrieve the token from the thread to make updates.
The
code sample in Example: Custom propagation token login module shows how to determine if the login is an initial
login or a propagation login. The difference between these login types is
whether the WSTokenHolderCallback callback contains propagation data. If the
callback does not contain propagation data, initialize a new custom propagation
token implementation and set it on the thread. If the callback contains propagation
data, look for your specific custom propagation token TokenHolder instance,
convert the byte array back into your customer PropagationToken object, and
set it back on the thread. The code sample shows both instances.
You
can add attributes any time your custom propagation token is added to the
thread. If you add attributes between requests and the getUniqueId method
changes, the Common Secure Interoperability Version 2 (CSIv2) client session
is invalidated so that it can send the new information downstream. Adding
attributes between requests can affect performance. In many cases, you want
the downstream requests to receive the new propagation token information.
To
add the custom propagation token to the thread, call the WSSecurityPropagationHelper.addPropagationToken
token. This call requires the WebSphereRuntimePerMission "setPropagationToken"
Java 2 Security permission.
- Add your custom login module to WebSphere Application
Server system login configurations that already contain the com.ibm.ws.security.server.lm.wsMapDefaultInboundLoginModule
login module for receiving serialized versions of your custom propagation
token You can also add this login module to any of the application
logins where you might want to generate your custom propagation token on the
thread during the login. Alternatively, you can generate the custom PropagationToken
implementation from within your application. However, to deserialize it, you
need to add the implementation to the system login modules.
For information
on how to add your custom login module to the existing login configurations,
see Developing custom login modules for a system login configuration.