Editing Service Location Protocol (section)

== Overview ==
SLP is used by devices to announce ''services'' on a local network. Each service must have a [[Uniform Resource Locator|URL]] that is used to locate the service. Additionally it may have an unlimited number of name/value pairs, called ''attributes''. Each device must always be in one or more ''scopes''. Scopes are simple strings and are used to group services, comparable to the ''network neighborhood'' in other systems. A device cannot see services that are in different scopes.

The URL of a printer could look like:
 service:printer:lpr://myprinter/myqueue

This URL describes a queue called "myqueue" on a printer with the host name "myprinter". The protocol used by the printer is [[Line Printer Daemon protocol|LPR]].  Note that a special URL scheme "service:" is used by the printer. "service:" URLs are not required: any URL scheme can be used, but they allow you to search for all services of the same type (e.g. all printers) regardless of the protocol that they use. The first three components of the  "service:" URL type ("service:printer:lpr") are also called ''service type''. The first two components ("service:printer") are called ''abstract service type''. In a non-"service:" URL the schema name is the service type (for instance "http" in "http://www.wikipedia.org").

The attributes of the printer could look like:
 (printer-name=Hugo),
 (printer-natural-language-configured=en-us),
 (printer-location=In my home office),
 (printer-document-format-supported=application/postscript),
 (printer-color-supported=false),
 (printer-compression-supported=deflate, gzip)
The example uses the standard syntax for attributes in SLP, only newlines have been added to improve readability.

The definition of a "service:" URL and the allowed attributes for the URL are specified by a ''service template'', a formalized description of the URL syntax and the attributes. Service templates are defined in RFC 2609.

SLP allows several query types to locate services and obtain information about them:
* It can search for all services with the same service type or abstract service type
* The query can be combined with a query for attributes, using [[Lightweight Directory Access Protocol|LDAP]]'s query language.
* Given its URL, the attributes of a service can be requested. In standard SLP the attributes are not returned in the query result and must be fetched separately. The Attribute List Extension (RFC 3059) fixes this problem.
* A list of all service types can be obtained
* A list of all existing scopes can be requested.