1. PaaSport - 605193 www.paasport-project.eu PaaSport Semantic Models Nick Bassiliades International Hellenic University (IHU) Semantic Models - Training material

2. PaaSport - 605193 PaaSport Architecture 2 www.paasport-project.eu Semantic Models - Training material

3. PaaSport - 605193 The role of the PaaSport Semantic Models Annotation of registered PaaS offerings and the deployed applications profiles Common vocabulary for system modules PaaSport Offering Recommendation layer –Matchmaking is performed using concepts and properties of the offering and application ontologies Persistence layer –DB schema follows the conceptual model of the ontologies; No mismatch Adaptive front-ends layer –UIs for managing application and PaaS offering profiles use concepts and properties from semantic models 3 www.paasport-project.eu Semantic Models - Training material

4. PaaSport - 605193 PaaSport Semantic Models have been defined as an extension of the Descriptions and Situations (DnS) pattern One (1) core model Three (3) contextualized extensions of the core pattern –Offerings –Applications –SLAs Semantic Models - Training material Semantic Models 4 www.paasport-project.eu

5. PaaSport - 605193 PaaS Offering Ontology Semantic Models - Training material 5 www.paasport-project.eu

6. PaaSport - 605193 Semantic Models - Training material 6 www.paasport-project.eu Offering Explanation Every Offering has an Offering Description (GroundOffering) Each parameter either has a value (without measurement unit, e.g. name) or parameterizes one Quality Value, that consists of a measurement unit and a data value (e.g. Latency-> 10msec) Every Offering Description consists of (offers) some PaaS Concepts, such as Programming Environment, Services, Resources, QoS etc Each Concept has some Parameters e.g. the QoS has parameter Latency

7. PaaSport - 605193 Semantic Models - Training material 7 www.paasport-project.eu Application Ontology

8. PaaSport - 605193 Application Explanation Every Application has a Description (satisfies some ApplicationRequirement) Each parameter either has a value (without measurement unit) or parameterizes one Quality Value, that consists of a measurement unit and a data value Every Application Requirement requires some PaaS Concepts, such as Programming Environment, QoS etc Each Concept has some Parameters e.g. the QoS has parameter Latency. Some Parameters are functional, whereas some other are non-functional. For example the name of a database is functional. For nonfunctional parameters the user through the GUI can state if it will be considered as functional or not. E.g. Latency less than 10ms is absolutely needed.

9. PaaSport - 605193 SLA Ontology Semantic Models - Training material 9 www.paasport-project.eu SLA is an agreement between 2 parties, the service consumer and a specific PaaS Offering Provider. The level of service is defined in terms of performance and reliability. SLA has a period of validity (properties StartDate, EndDate) The performance described by QoS parameters and the pricing by pricing policy parameters which are the same with QoS and pricing from the PaaSConcept.

10. PaaSport - 605193 PaaSportConcept –Represents an abstract concept of a service e.g. database, QoS, programming language, etc. –Each PaaSportConcept is associated with one ore more PaaSportParameters PaaSportParameter –Classifies an entity, specifying the way it should be interpreted e.g. the value “0.09 seconds” refers to the Latency of the provided service –The value of the parameter is defined using the hasParameterDataValue property Technical Meeting, Athens, 11-12 November 2014 10 Core PaaSport Pattern

11. PaaSport - 605193 Core PaaSport Pattern Technical Meeting, Athens, 11-12 November 2014 11

12. PaaSport - 605193 Concept Hierarchy Semantic Models - Training material 12 www.paasport-project.eu

13. PaaSport - 605193 PaaSConcepts are divined into eight subclasses. ProgrammingEnvironment concept is further subdivided into programming framework and programming language Service subdivided into Database and Server. Semantic Models - Training material 13 www.paasport-project.eu PaaS Concepts

14. PaaSport - 605193 PaaS Parameters Semantic Models - Training material 14 www.paasport-project.eu

15. PaaSport - 605193 Semantic Models - Training material 15 www.paasport-project.eu PaaS Parameters Parameters are divided into two subclasses: InformationalParameters, MatchmakingParameters. Only MatchmakingParameters are visible when the application’s developer creates the profile of the application. So the matchmaking algorithm uses only the matchmaking parameters. Matchmaking parameters are subdivided into functional and non- functional parameters. Functional parameters can only be used as functional requirements by the GUI. Non-functional parameters can be used both as nonfunctional requirements and as functional ones by the GUI.

16. PaaSport - 605193 Semantic Models - Training material 16 www.paasport-project.eu Parameters of a Service

17. PaaSport - 605193 Semantic Models - Training material 17 www.paasport-project.eu Resource and resource parameters

18. PaaSport - 605193 Semantic Models - Training material 18 www.paasport-project.eu Programming Environment and parameters

19. PaaSport - 605193 Semantic Models - Training material 19 www.paasport-project.eu QoS and parameters

20. PaaSport - 605193 Upper limit on the percentage of CPU load after which the platform scales up –E.g. “scale up if CPU load is higher than 90%”. Can be interpreted in 2 ways: –Server-like application: limit to be as low as possible Handle as many new requests as possible Maximum acceptable limit: a “compatible” offering may offer the same or lower CPU load. –Data-intensive application: limit to be as high as possible Utilize CPU as much as possible Minimum acceptable limit; a “compatible” offering may offer the same or higher CPU load. Semantic Models - Training material 20 www.paasport-project.eu MaxCPULoad

21. PaaSport - 605193 Lowest limit on the percentage of CPU load below which the platform scales down –E.g. “scale down when CPU load is below 30%” Always interpreted in the same way –Needs to be as high as possible Platform will scale-down early enough so that the CPU load is maintained relatively high (e.g. at least 50%). Cost is saved (no need to pay for extra VMs when not really needed). –Minimum acceptable limit; a “compatible” offering may offer the same or higher CPU load. Semantic Models - Training material 21 www.paasport-project.eu MinCPULoad

22. PaaSport - 605193 Latency –Delay incurred due to communications. –Maximum latency of an offering –Maximum latency required by an application ResponseTime –Time elapsed between sending a request and the reception of the first response Uptime –Percentage of time in a specific period that the application is up and running, or the offering is available Semantic Models - Training material 22 www.paasport-project.eu Latency, ResponseTime, Uptime

23. PaaSport - 605193 Semantic Models - Training material 23 www.paasport-project.eu Pricing Policy and parameters

24. PaaSport - 605193 Values with a measurement unit for a specific physical/logical quality –E.g. frequency 1 GhZ, memory 2 GB Semantic Models - Training material 24 www.paasport-project.eu Quality Values

25. PaaSport - 605193 Single Values, symbolic or numeric, require exact match –E.g. service name, location Nominal Values, enumerated data types, exact match –E.g. programming language names Ordinal Values, ordered enumerated data types, exact match, order can be established for better or worse –E.g. language or DB version Range Values, numeric values, require range match –E.g. network latency “less than” or “equal” 10ms –4 types, according to the matchmaking profile of each parameter: Max, Min, MaxMin, MinMax Semantic Models - Training material 25 www.paasport-project.eu PaaSport Quality value types

26. PaaSport - 605193 Max –Range Value with a Max upper limit, both for Offering-Application –Matches “less than” or “equal”. –E.g. network latency “less than” or “equal” 10ms Min –Range Value with a Min upper limit, both for Offering-Application –Matches “greater than” or “equal”. –E.g. Minimum CPU Load “greater than” or “equal” 50% MaxMin –Range Value with a limit that is Max for the Offering, Min for Application –Matches “less than” or “equal”. –E.g. Network Bandwidth: Offering gives maximum 1GB/s, application requires minimum 512MB/s MinMax –Range Value with a limit that is Min for the Offering, Max for Application –Matches “greater than” or “equal”. –Currently not used; may be useful in a future extension Semantic Models - Training material 26 www.paasport-project.eu Range values

27. PaaSport - 605193 Semantic Models - Training material 27 www.paasport-project.eu Full Offering example

28. PaaSport - 605193 Semantic Models - Training material 28 www.paasport-project.eu Full Application example