# 2 Introduction

## 2.1 Specification Organization

This document, the SIF Infrastructure Implementation Specification, contains the SIF Infrastructure. This includes Architecture, Messaging, and Infrastructure sections. A separate document, the SIF Data Model Implementation Specification, contains the SIF Data Model. See Chapter 1, Preamble, for an explanation of Infrastructure and Data Model. This document will be of interest to technical readers, including software architects, developers and integrators.

- The Preamble provides an abstract of SIF along with the SIF Association disclaimer and details regarding certification and compliance claims.
- This Introduction outlines the organization of the specification, provides conventions used in this document, and summarizes versioning of the specification. Highlights of additions/changes since the previous version of the specification are also provided.
- Architecture describes the assumptions, concepts, models, and requirements related to the SIF infrastructure and data model.
- Messaging details the actions Agents and Zone Integration Servers take when sending and receiving messages.
- Infrastructure provides definitions of the XML structure of elements, messages and objects related to SIF infrastructure as opposed to data in the pK-12 environment.
- The document concludes with various appendices including lists of code set values defined within SIF and in external documents, and ends with a list of references to other documents.

## 2.2 Document Conventions

### 2.2.1 Definitions

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

### 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 occurring 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 EMPHASIZED, 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 marked with ellipses, e.g., `| ...`

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 2.4

This release contains the following significant updates and extensions to the SIF Infrastructure Implementation Specification.

### 2.4.1 New Web Services Transport

The new Web Services (SOAP) transport is defined in an appendix to the v.2.5 Infrastructure document. For SIF v2.5, this appendix section is self-contained and completely specifies how to use SOAP and WSDL to transport SIF data objects. In a future release, this section may become more integrated with the rest of the Infrastructure document.

### 2.4.2 Directed Events

An optional feature related to Event and Service Notify messages has been added. In past releases, the ZIS would ignore the Destination Id element and distribute the Event to all subscribed agents in the zone. Beginning with this release (v. 2.5) the ZIS will route the Event (or Service Notify) message only to the agent specified in the Destination Id element, if the element is present. The handling of Destination Id information is described in section 5.1.3 of the SIF Infrastructure Implementation Specification.

### 2.4.3 Stand-Alone Transports

As a result of the work accomplished in version 2.5, we now have two stand-alone transports that can be used with any existing or future data model, namely:

1. The Web Services transport, and
2. The traditional HTTP/HTTPS transport.

### 2.4.4 Infrastructure Documentation

The following documentation changes have been made to the Infrastructure chapters of the Specification. No changes to the meaning or intent of the Specification were made as a result of these edits:

- Chapters 3 and 5 have been edited for clarity and Standard English language usage.
- Flow Charts have been added to Infrastructure Chapter 4 to help clarify the messaging protocols. A note has been included that if the text and the chart conflict, the text always takes precedence.
- Orphan (never used) types have been removed.
- Some paragraphs or small sections have been rearranged or brought together to reduce confusion or conflicting statements on a topic.