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FIMS v1.1 Version numbers in schema

FIMS v1.1 Version numbers in schema. Richard Cartwright Quantel July 2013. Always a client and server …. Combinations 1.1 orchestrator requests to 1.0.7 service 1.0.7 service responds to 1.1 orchestrator Or 1.2 and 1.1, or 1.2 and 1.0.7

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FIMS v1.1 Version numbers in schema

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  1. FIMS v1.1Version numbers in schema Richard Cartwright Quantel July 2013

  2. Always a client and server … • Combinations • 1.1 orchestrator requests to 1.0.7 service • 1.0.7 service responds to 1.1 orchestrator • Or 1.2 and 1.1, or 1.2 and 1.0.7 • … and for notifications, clients become servers, servers become • Requirements • A family of "backwards compatible" clients and servers where the major version number is the same. • Major version number only changes on big changes: • e.g. Move from XML to JSON • Fundamental change to data model • Avoid the web browser implementation headache (all HTML versions) while making interoperability OK for users • Is it possible?

  3. Likely changes • Attributes • adding – older versions should ignore • ##other – means new attribute is an error • removing – unlikely • changing type – ignore enumerations you don't know? • Complex types and elements • Adding – preferably at the end of a sequence – older ignores • ##other – means new elements are an error • Removing – unlikely • changing type • changing cardinality – maxOccurs = 1 to unbounded • (just a couple of minOccurs = 1 to 0 in capture service) • WSDL/SOAP: XML change • REST: XML or headers

  4. Forgiving reader, compliant writer • XML schema under- and over- constrains • Under: Difference between request, response • Over: Sequences • Validate during development? or at runtime? • Auto-generation frameworks • Don't automatically deal with multiple versions • Needs mitigation – unexpected cost • XML parser without schema • Can be built to be more forgiving • Implementation guidelines section

  5. Labeling the versions • Enable analyzers and tools to be more or less forgiving • Extreme: AAF requires meta model to be embedded ✗ • Choice of representation • Add elements or attributes to resource, fault, … etc.. • Don't confuse FIMS version with resource revision • SMPTE approach within MXF (e.g. major = 1, minor = 3) • Encode in the namespace • E.g. http://base.fims.tv/1.1 • SMPTE approach to XML schemas • Choice of location • Add to the resource ref & fault type => notifications • Everything data rather than message mechanics • Add to messages (WSDL-SOAP) and headers (REST)

  6. Examples • POST .../api/job <bms:job xsi:type="tran:TransferJobType" xmlns:tran="http://transfermedia.fims.tv" xmlns:base="http://base.fims.tv" xmlns:xsi="http://www.w3.org/2001/ XMLSchema-instance" version="1.1"> <base:resourceID>101…</base:resourceID> <base:priority>low</base:priority> … • Or version="1.1" ✓ • Or add tertiary="7" for 1.0.7

  7. Version check API • Do we need an API • Servers and clients can check before messages • Central repo of systems and version numbers

  8. Discussion • Version numbers as attributes or in the namespace? • Attribute • Mandatory or optional? How to deal with 1.0.7? • Mandatory from 1.1 onwards • No attribute = 1.0.7 • Version attribute location – Resources, faults, messages (…request, …response), headers • Proposal yesterday: put at both resource and message levels • What about mixed mode messages? • Alternative: Force client and server to use same version, then only at the message level? • Create mapping … document the delta • Different endpoints, one per version – use redirection • Fault message … but what about the legacy? Do we need a version on fault at all? • Send a 1.1 message to 1.0.7, it will fault? • Orchestration is configured with locations • Agreed proposal: One endpoint per version – should reject messages of the wrong version • SOAP: Version numbers in request messages • SOAP: Responses also have a message, shall match request • Faults – no version number • SOAP: Notifications – version number, shall match initial request and response • SOAP: Events – Match the version of the endpoint • RCR is a good place to put version information and version check API – get versions returns all known endpoints with their versions – please can the repository group add this soon? • REST: All HTTP requests and responses have header property: X-FIMS-Version • REST: Events need to carry version details

  9. Agreed Proposal • One endpoint per version – should reject messages of the wrong version • SOAP: Version numbers in request messages • SOAP: Responses also have a message, shall match request • Faults – no version number • SOAP: Notifications – version number, shall match initial request and response • SOAP: Events – Match the version of the endpoint • RCR is a good place to put version information and version check API – get versions returns all known endpoints with their versions – please can the repository group add this soon? • REST: All HTTP requests and responses have header property: X-FIMS-Version • REST: Events need to carry version details

  10. Actions • Add version attributes to 1.1 schemas – RIC/Ash • Create new fault type: SVC_S00_0019 • Version mismatch. – RIC/Ash - Done • REST … add new header - RIC • Text in part 1 document to describe - RIC • Implementation guidelines - All • Translation service

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