About Service Discovery Architecture

Service Location Protocol: Directory Agents are the renaming of MGs or various central authorities. Service and User Agents resides on the mobile devices and work the same as a subset of the CORBA framework components.

JINI: Has a Jini Lookup Service (JLS), exactly as MG.

Universal Plug and Play: UPnP uses SSDP over HTTP in two fashions, UDP(HTTPU) and UDP(HTTPMU). A service joining can unicase or multicase to the default selected set of clients or peers about it's arrival in the network and start of service. A client can directly contact a server based on URL or can multicase a request. UPnP seems to be a resonably good one since its architecture says 'NO' to centralized directory server.

SALUTATION: The salutation architecture defines another centralized entity as Salutation Manager (SLM), exctly as SLP's Directory Agent, or JINI's JLS or Nomadic's MG.

CONCLUSIVE POINTS
About UpnP
Hence, I am going to write or delve deeper into Universal Plug and Play only in the further blog contents. UPnP has five steps in all:

Discovery:

Based on SSDP over HTTP. When a device comes it multicast to the control point about it's service description. When a control point comes, it searches for devices of interest on the network.

Description:

After discovering the device, the control center retrieves the device (I assume service too) description from the URL provided by the device.

Control:

Control point sends control message to the control URL for the service.

Eventing:

In case service changes any of the service variables or other information about itself, it informs the control center with a event message about the change.

Presentation:

Some devices provides a URL like MBeans to allow a user to view device status or control the device.
About SLP

Advantage factor of SLP is that it supports service browsing and string based query.

About Nomadic

Cooperation among MG's in nomadic environment is also a good thing to do.

Few Points
Advantage of Nomadic over MANET are:

Scalability

Response Time

Load Balancing

Dimensions of Discovery

I can classify various discoveries in MANET and Pervasive computing as:
a.) Route Discovery
b.) Device Discovery
c.) Service Discovery

I can also classify demises in:
a.) Device Demise
b.) Service Demise
c.) Route Demise

I can classify the maintainance as:
a.) Route Maintainance

As far as Demise and Discovery dimensions are concerned:
Device property is a superset of the Service property. That means that happening of the Device entity would result in the same happening of the Service entity.