6.1.3 Cost without XML

Since XML processing is needlessly expensive, lets analyze what the cost could be with non-XML protocols like RESTful approach using Simple Web Tokens [Hardt09].

Table 8:Table 6.5: Cost of TAS³ single use scenario without XML

Operation	IdP + Disc	Frontend	FE PDP	Responder	Rs PDP	Audit Bus	Audit Bus PDP
1. SSO	2T+4S=7	4T+3S=9	2T+2S+Z=5.5			4(2T+S)=16	4(T+Z)=8
2. Discovery	2T+3S=6	T+S=2.5				2T+S=4	T+Z=2
3. Trust & Priv.	T=1.5				2T+S=4	2T+S=4	T+Z=2
4. Rq Out PEP		T=1.5	2T+2S+Z=5.5			2T+S=4	T+Z=2
5. Send request		2T+2S=5		2T+3S=6		2(2T+S)=8	2(T+Z)=4
6. Rs In PEP				T=1.5	2T+2S+Z=5.5	2T+S=4	T+Z=2
7. Payload
8. Rs Out PEP				T=1.5	2T+2S+Z=5.5	2T+S=4	T+Z=2
9. Send response		T+2S=3.5		T+2S=3.5		2(2T+S)=8	2(T+Z)=4
10. Rq In PEP		T=1.5	2T+2S+Z=5.5			2T+S=4	T+Z=2
11. Process Obli		2T+S=4		2T+S=4		2(2T+S)=8	2(T+Z)=4
12. SLO	2T+2S=5	2T+2S=5				2(2T+S)=8	2(T+Z)=4
TOTAL	7T+9S=19.5	14T+11S=32	6T+6S+3Z=16.5	7T+6S=16.5	6T+5S+2Z=15	36T+18S=72	18T+S+X+18Z=36

Without the XML, but otherwise fully featureful architecture leads to grand total of 94T+55S+0X+23Z=207.5 RSA equivalents. Thus eliminating XML can lead to over 40% of savings.