The following shows an example of transport guaranetee entry from web.xml:
Even if the client is accessing through plain text port, WLS container will automatically redirect the request to the SSL port if enabled or to any other Network Channel enabled with SSL. This will ensure that certain applications or requests to be always accessed through SSL. Setting the transport guarantee to be NONE will relax the requirements and will not force SSL for the applications. But if there are SSL enabled network channels or SSL port is enabled on the server then the application can still be accessed using SSL. If the value for transport guarantee is set to be INTEGRAL then the requirement is that the data sent between the client and server be sent in such a way that it can't be changed in transit.
Needless to say that this configuration can also be configured through deployment plans. If the application you are deploying on WebLogic Server is already packaged for deployment or third-party application then deployment plan will solve the purpose of overriding the application's configuration through external means. See here for more information on deployment plans with WebLogic Server.