This work is sponsored by  Office of Naval Research (ONR) 
as part of the DoD Multidisciplinary University Research Initiative (MURI) Project CONTESSA
 

Overview:

Our proposed solutions are implemented in the context of the MAPGrid system being developed at UCI. To allow for easy extensibility and re-use, the prototype MAPGrid implementation uses the Globus Toolkit, along with standardized messaging interfaces such as XML for metadata exchange. The initial prototype of MAPGrid assumes a WLAN infrastructure.

We design a middleware framework (shown in Fig 1) that provides efficient multimedia streaming services to mobile clients in grid-based environments. Various middleware services are executed on different system entities i.e. the broker, grid volunteer servers (VSs) and mobile clients (MCs). The Broker is assumed to be a high end server and is responsible for global adaptations in the system. Its request scheduler component performs power-aware admission control and decides the optimal video quality for incoming requests by selecting grid VSs to service the request's entire duration. The broker's directory service (DS) module provides global state information about clients and resource availability of VSs; and the lifetime management and service completion control modules handle VS failures and service migrations within the grid. Data placement strategies for replicating video object data are executed by the placement management module of the broker.

In this framework, grid volunteer servers (VSs) are defined as a machine that participates in the grid by supplying idle resources when they are not being used, i.e. VSs are intermittently available. VSs provide high capacity storage to store multimedia data, CPU for multimedia transcoding, decompression and/or buffer memory. Additionally, VSs can be used to perform adaptive network transmission that facilitates effective dynamic power management of device NICs (network interface cards). Each VS downloads video replicas from a tertiary storage and performs dynamic video transcoding with adaptive network transmission.

Figure 1. MAPGrid System Architecture

A mobile client (MC) (e.g. PDA, laptop etc.) runs a streaming multimedia application (e.g. MPEG player), and receives video streams from different VSs. The energy optimization module at MCs and the transcoding module at VSs adopt techniques developed in the DYNAMO project. The system is under-development, and an initial prototype implementation is ready for a video streaming application (as shown in Figure 2). 

Figure 2. Demo for a video streaming application

Software:

Our broker and VS can run on any operating system that supports Globus installation, and we recommend to use machines that at least have 128MB memory. Currently we have tested the client's application on laptop machines, and we are about to test it on PDAs, e.g. Zaurus SL-6000L.

To run the program, the broker needs to install Ant, Globus Toolkit, Java 1.4.2, and MySQL (if possible); VSs need to install Ant, Globus Toolkit, Java 1.4.2; and Jigsaw Server; laptop clients need to install Ant, Globus Toolkit, Java 1.4.2, and JMF (Java Media Framework).  Please contact Yun Huang for program and tutorial.

Collaborations:

The initial MAPGrid system prototype is implemented for mobile users that have WLAN connectivity. To incorporate ad hoc nodes into mobile clients of MAPGrid, we integrate the Limone system from Washington University, which is a lightweight coordination middleware facilitating distributed application development in mobile ad hoc networks, via an interoperable Veneer layer. Figure 3 illustrates the idea of multi-dimensional interoperability, i.e. mobile hosts can use fixed grid resources within their communication range to get services with high QoS, even if mobile hosts are not able to access resources available in fixed network, they will still be capable of communicating with nearby ad hoc group members to get same services but with low QoS.

Figure 3. Multi-dimensional Interoperability

Demo for Multi-dimensional Interoperability:

This demo demonstrates a military application scenario, and it has been presented at the ONR meeting  in Nov. 2004. We used a Linksys wireless-g broadband router and 3 laptops (one IBM T42 with Windows XP for broker, one SONY VAIO with Linux for the VS, one IBM T41 with Windows XP for proxy) to form a "grid" network. The mobile devices include 2 Dell Axim PDAs and one Sharp Zaurus SL-6000L. As there is no light version of Globus Toolkit for thin device (like PDA), we used a grid proxy to bridge the connection between handheld devices and the grid Broker. Please contact Yun Huang for the program.

Figure 4. Multi-dimensional Interoperability