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perfSONAR: Schema, Topology and Discovery

perfSONAR: Schema, Topology and Discovery. Martin Swany. OGF IPR Policies Apply. “ I acknowledge that participation in this meeting is subject to the OGF Intellectual Property Policy. ”

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perfSONAR: Schema, Topology and Discovery

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  1. perfSONAR:Schema, Topology andDiscovery Martin Swany

  2. OGF IPR Policies Apply • “I acknowledge that participation in this meeting is subject to the OGF Intellectual Property Policy.” • Intellectual Property Notices Note Well: All statements related to the activities of the OGF and addressed to the OGF are subject to all provisions of Appendix B of GFD-C.1, which grants to the OGF and its participants certain licenses and rights in such statements. Such statements include verbal statements in OGF meetings, as well as written and electronic communications made at any time or place, which are addressed to: • the OGF plenary session, • any OGF working group or portion thereof, • the OGF Board of Directors, the GFSG, or any member thereof on behalf of the OGF, • the ADCOM, or any member thereof on behalf of the ADCOM, • any OGF mailing list, including any group list, or any other list functioning under OGF auspices, • the OGF Editor or the document authoring and review process • Statements made outside of a OGF meeting, mailing list or other function, that are clearly not intended to be input to an OGF activity, group or function, are not subject to these provisions. • Excerpt from Appendix B of GFD-C.1: ”Where the OGF knows of rights, or claimed rights, the OGF secretariat shall attempt to obtain from the claimant of such rights, a written assurance that upon approval by the GFSG of the relevant OGF document(s), any party will be able to obtain the right to implement, use and distribute the technology or works when implementing, using or distributing technology based upon the specific specification(s) under openly specified, reasonable, non-discriminatory terms. The working group or research group proposing the use of the technology with respect to which the proprietary rights are claimed may assist the OGF secretariat in this effort. The results of this procedure shall not affect advancement of document, except that the GFSG may defer approval where a delay may facilitate the obtaining of such assurances. The results will, however, be recorded by the OGF Secretariat, and made available. The GFSG may also direct that a summary of the results be included in any GFD published containing the specification.” • OGF Intellectual Property Policies are adapted from the IETF Intellectual Property Policies that support the Internet Standards Process.

  3. Schema • Key Goals: Extensibility, Normalization, Readability • Break representation of performance measurements down into basic elements • Data and Metadata • Measurement Data • A set of of measurement events that have some value or values at a particular time • Measurement Metadata • The details about the set of measurement data

  4. Schema Normalization • Can simply the database representation for many types of measurement data • While optimizations are certainly possible, many measurement types can be viewed as one value over time • Assists Combination/Concatenation of metrics • Creating derived metrics • Normalization helps with inferring relationships between types of metrics

  5. Schema Basic Elements - Metadata • Subject • The measured/tested entity • Characteristic/Event Type (Verb) • What type of measurement, value, or event occurred • Parameters (Adjectives and Adverbs) • How, or under what conditions, did this event occur?

  6. Schema Basic Elements - Data • Some sort of value - Datum • Existence of an event might point to the case where there no additional value • As in “Link up/down” or threshold events • Time • Must be extensible since even agreement about the right structure is not easy • E.g. UNIX timestamp vs NTP time

  7. A Message Metadata Data Message Message

  8. An Object Store Metadata Data Store

  9. A Data is Linked to a Metadata Metadata <id>someId</id> Data <metadataIdRef> someId </metadataIdRef>

  10. A Metadata may be linked to another Metadata <id>someId</id> Metadata <id>someOtherId</id> <metadataIdRef> someId </metadataIdRef>

  11. Schema Namespaces • All measurements have some sort of Data and Time • All measurements can be described by the Metadata identifying who, what and how • The specific structures of the Data and Metadata elements depend on the measurement • Approach: Consistently use Data and Metadata elements and vary the namespaces of the specific elements

  12. Schema Namespaces - 2 • Why encode the measurement/event type in the namespace? • The encoding is essentially redundant • Some components of the system can pass Data and Metadata elements through without understanding their specific structure • Allows and implementation to decide whether it supports a particular type of data or not • Allows validation based on extended (namespace-specific) schemata

  13. Schema Namespaces and Extensibility • One key to extensibility is the use of hierarchy with delegation • Similar to OIDs in the IETF management world • The Global Grid Forum’s NM-WG has a hierarchy of characteristics • Good starting point • However, not all tools are cleanly mapped onto the Characteristic space • Often a matter of some debate

  14. Schema Namespaces and Extensibility - 2 • Organization-rooted tools namespace addresses this • Some top-level tools • ping, traceroute • Easy to add new tools in organization-specific namespaces • Performance Event Repository • Add a schema and get a URI • Add Java classes

  15. Versioning Example <nmwg:message id="snmpmsg5" type="MetadataKeyRequest" xmlns:nmwg="http://ggf.org/ns/nmwg/base/2.0/" xmlns:snmp="http://ggf.org/ns/nmwg/tools/snmp/2.0/" xmlns:nmwgt="http://ggf.org/ns/nmwg/topology/2.0/"> <nmwg:metadata id="meta2"> <snmp:subject id="subject2"> <nmwgt:interface> <nmwgt:hostName>scotch.pc.cis.udel.edu</nmwgt:hostName> <nmwgt:ipAddress type="ipv4">128.4.133.141</nmwgt:ipAddress> </nmwgt:interface> </snmp:subject> <nmwg:eventType>SNMP.Get.Request</nmwg:eventType> </nmwg:metadata>

  16. Versioning • Separate revisions of base schema and eventType schema • Open Issues: • Query for supported versions must be defined • This will enable a migration strategy

  17. Topology Schema

  18. Topology Schema • Topology schema • Reusable Subject elements for common cases • Also reduces redundancy • Relationships between Subjects • Same basic structure at all layers • Networks are graphs • Define: • Nodes • Interfaces • Links • Networks

  19. Topology

  20. Topology - Recursive Links

  21. Topology Schema • Structured by layers and the same elements recurring there • Varied again by namespaces • Reuse visualization logic, etc. • 4 Layers: Base (both abstract and L1), L2, L3, L4 <?xml version="1.0" encoding="UTF-8"?> <nmwg:store xmlns:nmwg="http://ggf.org/ns/nmwg/base/2.0/" xmlns:nmwgt="http://ggf.org/ns/nmwg/topology/3.0/" xmlns:nmwgtl3="http://ggf.org/ns/nmwg/topology/l3/3.0/" xmlns:nmwgtl2="http://ggf.org/ns/nmwg/topology/l2/3.0/">

  22. Relationships between Subjects • To completely capture the relationships, we need to do a few more things • Recursive definition of links • Logical links consist of physical links • Ordered lists of links • Like above, but we need to introduce an Index attribute • Networks • Physically consist of links but that is not always the most convenient logical view • Special element to which Interfaces or Links belong

  23. Relationships between Subjects • Elements at the same layer have relationships • A link “contains” two interfaces • At Layer2 or Layer3 • Elements of the same sort have relationships between themselves at different layers • A Layer 1 Interface (physical NIC) can have one or more Layer 2 Interfaces, which can each have one or more Layer 3 Interfaces • Node is special • Since a Node doesn’t really have any higher-layer characteristic independent of its Interfaces

  24. Schema Status • Three documents in preparation for OGF • Base Schema • Topology Schema • Extension guide • With examples of utilization, traceroute, ping • Drafts to NMWG by January • OGF meeting in February

  25. Schema Status • Three schema components • Base • Defines Message, Store, Data, Metadata, Parameters • Topology • Defines Subjects that can appear in the Metadata and Version 3 represents their relationships as well • EventTypes • Each data type extends the Base and can define what Parameters are acceptable and what subjects are required

  26. Outstanding Issues • Namespaces for Message types • Currently a simple text field, but namespaces might make Message syntax/semantics easier to track (and version) • Uniform EventTypes that match the EventType namespace • XML Factoring to further reduce redundant information • Some work at UD on “views”

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