2 Introduction

2.1 Specification Organisation

Beyond the abstract and this introduction, educators and non-technical readers are typically interested in the escs data objects that can be shared and reported on by SIF-enabled applications in SIF implementations. These are presented in the Data Model section in a format that should not be a barrier to readers with a background that includes a brief introduction to [XML], though they may benefit from the introductory sections of Architecture. Technical readers, including software architects, developers and integrators, should have a solid background in Architecture, Messaging, Infrastructure and Data Model.

2.2 Document Conventions

2.2.1 Definitions

The first time a term or concept is defined, it may be emphasised.

2.2.2 Structure and Values

SIF message and object names, XML element tags, attribute names and values, and other codes or values are typically presented as in this sentence.

2.2.3 Examples

Longer examples of XML or HTTP messages are typically numbered and presented as given here.
Example 2.2.3-1: Examples Convention

2.2.4 References

References to other works occuring in this text are given in brackets, e.g. [REFERENCE]. The text in brackets corresponds to a key in the References appendix. Often when the text in the brackets duplicates surrounding text, the reference alone is used (e.g. [XML] instead of XML [XML]).

2.2.5 Terminology

The key words MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD, SHOULD NOT, RECOMMENDED, MAY, OPTIONAL, when EMPHASISED, are to be interpreted as described in [RFC 2119].

2.2.6 XML Diagrams

Quick overviews of XML structures, including messages, objects, common elements and types, are provided in XML diagrams. The following diagram illustrates the conventions typically encountered in SIF.

Figure 2.2.6-1: XML Diagram Conventions

XML elements are represented by rectangles with the name of the element in the upper portion and the type, if any, in the lower portion. Attributes are represented in the same fashion, but have an @ icon rather than a SIF icon. Elements and attributes that are optional have a circled ? (0 or 1 occurrence) to the left of the rectangle. Optional and mandatory repeatable elements are indicated by a circled * (0 or more occurrences) and + (1 or more occurrences), respectively. Element attributes are grouped together in a rectangular block and connected to the element with a line that turns at right angles. Ordered sequences of XML elements are bracketed by lines that turn at right angles. When a choice of XML elements is indicated, the elements are bracketed by angled lines. A choice of elements can occur within an element, or may be an unnamed choice of elements.

XML types are represented using the same conventions as for XML elements, though the type portion of the rectangle typically indicates a base type, if any.

The type name of any element, attribute or type may be prefixed with a , indicating the type is restricted in some fashion by one or more XML Schema facets (e.g. enumeration). When the type is a union of types, a list of types is presented, each type separated by |; if the list of union types is long, the list may be ellipted with | ...

In an actual XML diagram, element, type and attribute rectangles are usually linked to their corresponding definitions/descriptions in accompanying tables.

2.3 Version Numbers

The SIF Implementation Specification uses the following version numbering scheme:

major version . minor version r revision number

Major versions typically introduce additions/changes to the SIF infrastructure and/or data model changes that impact a significant percentage of SIF-enabled applications (e.g. making previously optional elements mandatory, removal of deprecated objects, elements or values). The first release of a major version has a minor version of 0 (2.0); major version numbers start at 1 and are incremented as major versions are released (1.0, 2.0, 3.0, ...).

Minor releases typically introduce new data objects, or optional additions to data objects, to the marketplace, and may include minor infrastructure additions/changes that do not impact existing SIF-enabled applications and that ZIS vendors have agreed to implement. The first minor version released subsequent to and within a major release has a minor version of 1 and is incremented as new minor versions are released (2.1, 2.2, ...). If a significant number of minor release features is introduced in a specification, the SIF Association may decide to increment the minor version number by more than 1 (e.g. 1.1 to 1.5), though a number like 1.5 is not an indication of being halfway to a major release, as minor version numbers may be incremented significantly past 10 (2.10, 2.11, ...) as data objects and other minor version features are released.

Corrections resulting from identified errata, as well as textual changes, may be incorporated into a revision release. These typically include minor corrections to messages or data objects, corrections of typographical errors, or corrected/expanded documentation. If major errors in any release are identified, a revision release may incorporate changes more typical of a major or minor release. First major and minor releases have a revision number of 0, which is omitted from the version number (2.0, not 2.0r0); subsequent revision numbers start at 1 and are incremented as new revisions are released (2.0r1, 2.0r2, ...).

2.4 Highlighted Additions/Changes Since Version 1.2

This release contains the following significant updates and extensions to the SIF specification.

2.4.1 Zone Services

Zone Services is the third major transactional model of the SIF Implementation Specification; joining the publish/subscribe and the request/response functionality. Zone Services provides its clients (existing SIF applications and other Zone Services) with the following capabilities:

Four new messages were added to the SIF infrastructure to support these capabilities: ServiceInput, ServiceOutput, ServiceNotification, and CancelServiceInputs. Message processing choreographies are described in Section 4: Messaging and message contents are defined in Section 5: Infrastructure.

Three sets of US-specific Zone Services are included with this release, all of which are defined in Section 7: Zone Services. These have been included in the UK specification as a guide to how Zone Services should be implemented. It is not expected that these should be used as is in the UK, but it was thought that their inclusion would be beneficial to simplify development of UK-specific Zone Services. The Zone Services included in Section 7 of this printed document are not included in the XSDs associated with the release because of their locale specific characteristics. Also, the Zone Services that appear in Section 7 are deprecated as of version 1.3 and will be replaced by UK-specific Zone Services.

The specific changes are detailed below.

2.4.2 Data Model

2.4.3 Infrastructure

2.4.4 Enhanced Security

An XML Filtering capability on both elements and messages has been defined for the ZIS to allow it to implement site-specific data security policies.

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