Web Service Level Agreement (WSLA)

Web Service Level Agreement (WSLA)

Language Specification

Revision: wsla-2003/01/28

Authors:

Heiko Ludwig, IBM T.J. Watson Research Center

Asit Dan, IBM T.J. Watson Research Center

An SLA also specifies the measures to be taken in case of deviation and failure to meet the

asserted service guarantees, for example, a notification of the service customer. The assertions

of the service provider are based on a detailed definition of service parameters including the

algorithms -- how basic metrics should be measured in systems and how they are aggregated

involved. To actually act as a participant in a WSLA, parties have various degrees of freedom to

Abstract ............................................................................................................................................ 2

1. Introduction ........................................................................................................................... 7

1.1. Summary ........................................................................................................................... 7

1.4.4. WSLA Creation......................................................................................................... 11

1.4.5. Deployment Process ................................................................................................ 12

1.5. Scope of the Specification............................................................................................... 13

1.6. Structure of the Document .............................................................................................. 13

1.7. Running Example ............................................................................................................ 14

1.8. WSLA Compliance Monitor Release Notes..................................................................... 15

2. Web Service Level Agreement Language .......................................................................... 16

2.1. Overview of the Main Concepts ...................................................................................... 16

2.2. Structure .......................................................................................................................... 17

2.3. Parties.............................................................................................................................. 18

2.4. Service Definitions........................................................................................................... 22

2.4.1. Service Definition ..................................................................................................... 22

2.4.2. Service Object .......................................................................................................... 23

2.4.3. Schedule .................................................................................................................. 24

2.4.4. Trigger ♠ ................................................................................................................... 24

2.4.5. Constant ♠ ................................................................................................................ 25

2.4.6. SLAParameter.......................................................................................................... 25

2.4.7. SLAParameter Communication................................................................................ 26

2.4.8. Metric........................................................................................................................ 27

2.4.9.

2.4.15. Measurement Directive Assignment..................................................................... 35

2.4.16. Service Level Objective ........................................................................................ 36

2.4.17. Action Guarantee.................................................................................................. 37

2.4.18. Obligation Group................................................................................................... 38

2.4.19. Obligations............................................................................................................ 38

2.4.20. Logic Expression .................................................................................................. 39

2.4.21. Binary Logic Operator........................................................................................... 39

2.4.22. Unary Logic Operator ........................................................................................... 40

2.4.23. Predicates............................................................................................................. 40

2.4.24. Qualified Action..................................................................................................... 40

2.5.5. Execution Modality ................................................................................................... 44

2.5.6. Operand ................................................................................................................... 45

2.5.7. Lists .......................................................................................................................... 46

3. Standard Extensions ........................................................................................................... 47

3.1. Extension Mechanism and Purpose of Standard Extensions ......................................... 47

3.2. Operation Descriptions .................................................................................................... 48

3.2.1. WSDL SOAP Operation Description ........................................................................ 48

3.3. Action Descriptions.......................................................................................................... 49

3.3.1. WSDL SOAP Action Description.............................................................................. 49

3.4. Measurement Directives.................................................................................................. 49

3.4.6.

3.5.4. Mean♠....................................................................................................................... 56

3.5.5. Median ♠................................................................................................................... 56

3.5.6. Mode ♠...................................................................................................................... 57

3.5.7. Round ♠ .................................................................................................................... 57

3.5.8. Sum .......................................................................................................................... 58

3.5.9. Max........................................................................................................................... 59

3.5.10. ValueOccurs ......................................................................................................... 59

3.5.11. Arithmetic Functions ............................................................................................. 60

3.5.12. PercentageGreaterThanThreshold ♠.................................................................... 60

3.5.13. PercentageLessThanThreshold ♠ ........................................................................ 61

3.6.2. Greater ..................................................................................................................... 65

3.6.3. Less.......................................................................................................................... 65

3.6.4. Equal ........................................................................................................................ 66

3.6.5. GreaterEqual ............................................................................................................ 66

3.6.6. LessEqual................................................................................................................. 66

3.6.7. True ♠ ....................................................................................................................... 67

3.6.8. False ♠...................................................................................................................... 67

3.7. Action Invocations ........................................................................................................... 67

3.7.1. Notification................................................................................................................ 67

3.8. Additional Data Types of the Standard Extensions......................................................... 68