GF.Header Modification

Data that is being transported is usually encapsulated in one or more layers, the outermost of which serve the network transport method(s). There are several reasons why an infrastructure facility might need to change information in (one or several of) these layers, for instance for routing purposes.

Other Building Block Types that have these specific needs for their own purposes include the necessary functionality (e.g. Load Balancing), but this separate Building Block Type has been created to serve the case where data encapsulation must be manipulated for other reasons.

A Header Modification Building Block can manipulate the encapsulation of a piece of data:
 * at the OSI layers 1 through 7 to serve an infrastructural goal, e.g. inserting headers plus data in HTTP packets in an authenticating proxy (e.g. IBM WebSeal, which adds authenticated users in the HTTP header as "iv-user");
 * to support an applicative goal from the infrastructure, or
 * to modify the headers of Messages (e.g. email or SOAP messages), e.g. inserting a line in an email message header to indicate the message has been scanned for viruses, or changing the recipient of a SOAP message (in a SOAP WSE router).