Hand Held Message Service (HHms)

 

By Sangyoon Oh

soh@csit.fsu.edu

 

 

1. Introduction

In the Garnet Architecture, supporting PDA – desktop collaborating is one of the distinct features. To achieve this, it is necessary to have a middleware, which helps communication between PDA clients and desktops. Since a PDA client does not have Garnet Message Service (GMS) capability in the Garnet Architecture, a middleware (called a PDA-adaptor) convert GMS message into a Hand Held Message Service (HHms). HHms protocol defines a communication line between a PDA-Adaptor and PDA devices. HHms guarantee the most efficient types of message, since PDA¡¯s relative low message processing ability is considered. Continuous big-size messages make another processing job and overhead to PDA¡¯s slow CPU. So HHms define protocol-frame, which contains information blocks. Each blocks substitutes GMS capability so that the Garnet system has flawless communication over all types of access. Fig. 1 illustrates communication between a PDA and a PDA-adaptor.

 

 

Figure 1. Communication Between PDA and PDA-adaptor

 

2. Frame Component

HHms contains five components:

  1. Machine ID (Only from the PDA-Adaptor to PDA)
  2. HHTopic
  3. HHApplication ID
  4. HHEvent ID
  5. HHEvent Data

 

2.1 Machine ID

A Machine ID is a connected device ID. A PDA-adaptor will give this ID, when PDA make a connection to Adaptor and register. This registration is including all initial jobs both a PDA and a PDA-adaptor. A PDA send its profile to Adaptor and a PDA-adaptor creates a Job queue for it. A job queue is an instant object, which provide a PDA interface as well as a queue function.  

 

2.2 HHTopic

An event is related with a topic. It is what topic of this message is about.

           

2.3 HHApplication ID

It is a pre-defined PDA application ID (such as Instant Messenger, SVG viewer, and Shared Display).

 

2.4 HHEvent ID

It is what event type of this message. Each PDA application has a major/minor event to share with same topic subscriber (Client).

 

2.5 HHEvent Data

It is an event body itself.

 

(a) From PDA to PDA-adaptor

(b) From PDA-adaptor to PDA

 

Figure 2.  HHms protocol-frame