This chapter describes the SLP status codes and message types. SLP message types are listed with the abbreviations and function codes. SLP status codes are shown with descriptions and function codes that are used to indicate that a request is received (code 0), or that the receiver is busy. The SLP daemon (slpd) returns status codes for unicast messages only. Status Type Status Code Description No Error 0 Request was processed without error. LANGUAGE_NOT_SUPPORTED 1 For an AttrRqst or SrvRqst, there is data for the service type in the scope, but not in the language that is indicated. PARSE_ERROR 2 The message fails to follow SLP syntax. INVALID_REGISTRATION 3 The SrvReg has problems. For example, a zero lifetime or an omitted language tag. SCOPE_NOT_SUPPORTED 4 The SLP message did not include a scope in its scope list that is supported by the SA or DA that answered the request. AUTHENTICATION_UNKNOWN 5 The DA or SA received a request for an unsupported SLP SPI. AUTHENTICATION_ABSENT 6 The UA or DA expected URL and attribute authentication in the SrvReg and did not receive it. AUTHENTICATION_FAILED 7 The UA or DA detected an authentication error in an Authentication block. VER_NOT_SUPPORTED 9 Unsupported version number in message. INTERNAL_ERROR 10 An unknown error occurred in the DA or SA. For example, the operating system had no remaining file space. DA_BUSY_NOW 11 The UA or SA should retry, using exponential backoff. The DA is busy processing other messages. OPTION_NOT_UNDERSTOOD 12 The DA or SA received an unknown option from the mandatory range. INVALID_UPDATE 13 The DA received a SrvReg without FRESH set, for an unregistered service or with inconsistent service types. MSG_NOT_SUPPORTED 14 The SA received an AttrRqst or SrvTypeRqst and does not support it. REFRESH_REJECTED 15 The SA sent a SrvReg or partial SrvDereg to a DA more frequently than the DA's min-refresh-interval. Message Type Abbreviation Function Code Description Service Request SrvRqst 1 Issued by a UA to find services or by a UA or SA server during active DA discovery. Service Reply SrvRply 2 The DA or SA response to a service request. Service Registration SrvReg 3 Enables SAs to register new advertisements, to update existing advertisements with new and changed attributes, and to refresh URL lifetimes. Service Deregistration SrvDereg 4 Used by the SA to deregister its advertisements when the service they represent is no longer available. Acknowledgment SrvAck 5 The DA response to an SA's service request or service deregistration message. Attribute Request AttrRqst 6 Made either by URL or by service type to request a list of attributes. Attribute Reply AttrRply 7 Used to return the list of attributes. DA Advertisement DAAdvert 8 The DA response to multicast service requests. Service Type Request SrvTypeRqst 9 Used to inquire about registered service types that have a particular naming authority and are in a particular set of scopes. Service Type Reply SrvTypeRply 10 The message that is returned in response to the service type request. SA Advertisement SAAdvert 11 UAs employ the SAAdvert to discover SAs and their scopes in networks where no DAs are deployed.