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Glossary

BNF

Backus–Naur form. A formal description of syntax used within a standard. The BNF description will show, for example, what characters can and cannot be used as a specific value. See more: http://en.wikipedia.org/wiki/Backus-Naur_form

Class

A sub-category of a RETS Resource. For example, the Property Resource may have RESI, COMI, LOTL, etc. as Classes.

Client

A software application which runs on a computer and relies on a server to perform some operations. For example: Microsoft Outlook may be your email client while Microsoft Exchange is the server which routes and stores your emails

Compact

A RETS client can request that the results to a query be in COMPACT format. The most basic explanation is that this is a tab-delimited file and the idea is that the bandwidth requirements are less than for representing the same data in STANDARD-XML format. Lookup data is provided in it’s coded format. COMPACT and COMPACT-DECODED formats will generally require that the client software utilize the server’s metadata to fully understand the fields presented.

Compact Decoded

Similar to COMPACT format, COMPACT-DECODED results are usually tab delimited. The major difference between COMPACT-DECODED and COMPACT is that COMPACT-DECODED results will have Lookup data in it’s most human readable format–coded fields will be expanded to something that is generally understandable to humans. Like COMPACT format, the client software will need to utilize the server’s metadata to fully understand the fields presented.

Compliance / Compliancy

Once a RETS client or RETS server has been developed, a Compliance test can be run to make sure that it follows the RETS standard. The tests are defined and designed by the Compliance Testing Workgroup.

DTD

Document Type Definition. These files are used to describe an XML document so a computer program can automatically “learn” how the XML is structured and what data types are used.

Data Elements

Pieces of information delivered from a server after a query and may include field values, images, URL’s, etc.

Data Recipient

Person or entity which receives, pulls or accesses MLS content.

Database Name

The unique identifier the MLS database uses to name a field. Some MLS databases use numeric database names

Database Server

The “backend” MLS system server which houses property, agent, office information as well as images, documents, etc. A database server is proprietary to the MLS vendor and works in conjunction with the MLS system software

FTP

File Transfer Protocol. FTP is a file transfer standard for moving static files from one computer to another.

Filtering

Applying rules to a User Agent, User Class, etc. which limits the data elements, amount of data, number of queries returned by a request for a specific User, User Class, User Agent, etc.

GUI

Graphical User Interface

GetObject

A RETS request type. The GetObject request is issued from a RETS client to a RETS server in order to obtain objects for a specific listing such as property photos or PDFs. The request can be for a single, specific object or can be issued to retrieve all objects.

HTTP

Hypertext Transfer Protocol. HTTP is the protocol the RETS 1.x family of versions use for communicating back and forth. Authentication is typically accomplished using either Basic or Digest authentication within HTTP. Request-specific values are passed to the server within the URL while the body of the response is returned back to the client in the HTTP body.

IDX

Internet Data eXchange. At it’s core, IDX is the concept of displaying property information from an MLS on an Internet website, although over the years, IDX has taken on different meanings. An “IDX feed” or “IDX file” is typically an exported file (once every 24 hours or so) that resides on an FTP server controlled by the MLS. “IDX vendor” is a term used to describe a 3rd party company that provides a product or service that makes use of data from an MLS.

Lookup

A field that contains preset codes as it’s value. For example: PropertyType might be a field that contains RES as it’s value. Doing a ‘METADATA-LOOKUP_TYPE’ request through RETS would tell you that PropertyType can contain RES (the code) for Residential (it’s value), CON for Condo, LAN for Land, COM for Commercial, etc.

Metadata

Metadata can be thought of as “data describing the data”. When used with RETS, retrieving the Metadata for a specific property class (example: Residential properties) will return very specific information about all of the fields, field types, which fields are searchable, etc. A “Metadata-aware” RETS client can use this information to automatically recognize changes to a data format (like when a field has been added) and adapt accordingly without user intervention (by adding a new field in their local database to make room).

Plugfest

Plugfest is an open workshop for technology partners to test their interoperability held during the trimester conferences. This is a popular event where some of the best technical staff from the industry meet to help each other connect using the RETS specification.

Query

A query is made up of different sub queries separated for logical operators. Each sub query can contain Sub Queries, Lookups, Ranges and Strings.

RCP

Rule Change Proposal. An RCP is a document which includes a possible rule change to the specified technical document. Once voted on and approved, the change described would be implemented into the standard.

RESO

Real Estate Standards Organization, a body that is a legal United States Corporation whose purpose is to govern the standards development, promotion, and maintenance activities of RETS and related activities.

RETS

Real Estate Transaction Standard

Request

An action performed against the server, such as a query, call for images, open house URL’s, etc.

Resource

The RETS term for a general category of data available through a RETS server. For example: Property, Agent, Tour, OpenHouse, etc.

SOAP

Simple Object Access Protocol. Provides a way to communicate between applications running on different operating systems, with different technologies and programming languages.

Schema

The structure of a database system, described in a formal language supported by the database. In a relational database, the schema defines the tables, the fields in each table, and the relationships between fields and tables. RETS Schema defines fields, data types and classifications.

Server

The Server is the central computer system which contains the desired information. A Server handles requests from Clients, applies business rules and other limitations on those requests (through filtering) and provides a valid data response back to the Client.

The pipe “|”

Means OR so everything separated by commas has is OR’ed.

The plus “+”

Means AND so everything separated by a comma is AND’ed.

The tilde “~”

Means NOT so everything separated by a comma is NOT’ed.

User Agent

A User Agent is the name a RETS client goes by and what version is currently being used. For example, a User Agent of RETSclient/1.0 shows that a user is using version 1.0 of a product called RETSclient. This “signature” is provided with each RETS request and can be used for authentication and/or filtering on the server.

User Class

See User Roles

User Roles

A group of users can be assigned specific user roles. Typically, these roles are used in combination with filtering so a group of users are assigned specific filtering. For example, any RETS user who is an IDX vendor can be assigned the “IDX Vendor” role and a specific filter can be applied to the group rather than to each user specifically.

Versioning

Mechanism which tracks all changes in content and code. For RETS, Versioning refers to the number associated or applied to the RETS Standard Documents, i.e. 1.5, 1.7, etc which have been voted and approved by the RETS Working Group.

WS (Web Services)

A standardized way of integrating web-based applications using the XML, SOAP, WSDL and UDDI open standards over the Internet protocol backbone.

XML

eXtensible Markup Language. XML is a custom markup language used by many general-purpose applications to exchange information. The tags used within XML are not pre-defined and can be anything that correctly describes the data. Data in this format is easy for a program to consume and use, regardless of the operating system or programming language used. Within RETS, the XML tags are pre-defined which make it easier for a single program to understand data that may come from different RETS servers.