HP-UX IP Address and Client Management Administrator's Guide HP-UX 11i v2, HP-UX 11i v3

Figure 1-6 SLP Architecture
In Figure 1-6, SAs contain service advertisements describing the services they represent. The
advertisement consists of service type, attributes, and service access point. UAs transmit queries
to the network about what services their clients require. The SAs intercept these queries and
return the service access point information if the query matches the service type and attributes
of the services they represent. The UA clients then utilize the services through the service access
point information.
SLP Attributes
Attributes in SLP are transmitted in text string lists. The lists contain parenthesized expressions
assigning an attribute tag to a value or a set of values. The syntax for the attribute string list is
as follows:
attrlist = *WS attr-assign *WS / *WS attr-assign *WS “,”
; attrlist
Attributes are formed into a list consisting of comma-separated expressions. The assignment
expressions contain the attribute tag, followed by "=", followed by a comma-separated list of one
or more values. An example of attribute list is as follows:
(submission day=wednesday),new_copy,(month=1,2,3,4,5,6)
In this list, the submission day is assigned a string value of wednesday; the month attribute is
assigned a list of integer values. The new_copy attribute is a keyword attribute and is not part
of an attribute assignment expression. SAs send attribute lists in this format to DAs in response
to a UA request for attribute values.
Discovering a Directory Agent
Following are the different ways in which UAs and SAs find DAs:
• Active DiscoveryIn active DA discovery, the UA and the SA send a multicast SLP request
to the network. The service type of the request is directory-agent, and the query is
empty. If the client wants to discover all DAs within its multicast radius, it does not include
any scope in the service request. DAs are required to reply with their service URLs and the
scopes that they support. The response to the service request message, however, is not a
service reply, but rather a DA advertisement. The service URL of a DA includes the host
name or IP address of the DA as shown in the following examples:
SLP Overview 55