MUM Architecture

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MUM Distributed Architecture

First and foremost, we claim that only management operations executed in client locality can guarantee service continuity by promptly foreseeing and reacting to client handoffs.

For that reason, MUM adopts a proxy-based infrastructure to grant service continuity and provides client devices with companion application-layer middleware proxies running at client access locality, i.e., Session Proxies, able to personalize service continuity management depending on and local executing context and client profile.
In addition, Session Proxies should be mobile to autonomously follow their roaming clients at provision time, to contribute to the automatic deployment of handoff management intelligence, and to re-distribute the service provisioning load within network access localities.

With more details, the distributed MUM architecture includes the following entities:

  • Session Proxy is responsible for transparent and proactive execution of adaptation and reconfiguration operations required by its client movements/handoffs. It executes in the client current wireless access network and exploits its full context awareness to act autonomously on client behalf; in addition, it maintains session state (data buffers, service binding information, …) of all continuous services currently accessed by the client device.

  • Service Gateway provides session proxies with a self-contained local executing environment and mediates session proxy access to system resources. MUM groups all Wireless Local Area Networks (WLANs) with the same network administration authority in a single Wireless Internet domain; for each domain, MUM deploys one service gateway re-sponsible for the session proxies of all clients in the included WI cells (see figure).

  • Client Stub implements middleware functions on the client side. MUM exploits client stub only to execute lightweight functions that require local access to the client device, e.g., to evaluate handoff predictions.

MUM Distributed Architecture

MUM Internal Architecture

The internal architecture of our MUM middleware implementation consists of several facilities, in the following (see figure) we report its main facilities. MUM session proxy and client stub are the components working to handle the handoff management process to maintain service continuity.


MUM Internal Architecture

Proxy/stub facilities include:

  • Handoff Prediction Monitor (HPM) to enable pro-activity at the middleware level
  • Service Continuity Manager (SCM) to grant timely delivery of multimedia data
  • Fast Service Re-binder (FSR) to accelerate component re-bind

Those three facilities form a pipeline; each stage of that pipeline exploits full context visibility and output data from the previous stage to trigger control actions over the following stage.



Service gateways comprise three generic facilities for continuous multimedia provisioning over the traditional Internet:

  • Context Information Store (CIS) to describes the local wireless Internet domain
  • Content Adaptors (CAs) to activate server-to-gateway paths and to dynamically adapt delivered contents by re-organizing delivery paths and by selecting appropriate content trans-coders
  • Session Proxy Manager (SPM) to support session proxy lifecycle and to enable their mobility


To ease integration with more traditional continuous service provisioning infrastructures MUM employs all most diffused standard application-level protocols: RealTime Protocol (RTP), Session Initiation Protocol (SIP), and RealTime Streaming Protocol (RTSP). In addition, to facilitate portability MUM is is implemented in Java and exploits pure-Java technologies such as Java Media Framework (JMF) and Java API for Integrated Networks (JAIN).