Proxy Repository

 The proxy repository is proposed to minimize the impact of remote code loading on the runtime behavior of the mobile code. If the connection between proxy repository and mobile code is based on fast and stable links, low latency and high reliability for the procedure of remote loading can be achieved. Hosts which are connected over fast and stable links build a neighborhood . The most desirable residence of a proxy repository is in the neighborhood of the mobile code. E.g. a LAN segment builds a neighborhood, but represents only a small number of hosts. This implies a big number of proxy repositories that must be set up if a mobile code moves to a lot of hosts in a complex network. The nature of the neighborhood is strongly application dependent. If e.g. neighborhood is defined as a subnet and a mobile agent visits exactly one host in the subnet, e.g. for configuration of DNS servers, a proxy repository is created on every host that is visited by the agent. In this scenario the concept of the proxy repository would not meet its goal, due to the unsuitable realization of the term neighborhood.

The proxy repositories can be started as a separate thread or process by the adaptation mechanism itself when it can not find a repository in the neighborhood. The started proxy repository serves to the mobile code as a replacement of the central repository . The mobile code does not contact the central repository any more, but the proxy repository for loading profiles or implementation classes instead.

 

Figure: Example for proxy repository  

Figure shows two neighborhoods and the route of a mobile code that moves in turn starting on host 1 to all others and terminates on host 7 as the last host. When the mobile code moves from host 4 to host 5 the neighborhood, e.g. the subnet, changes and the adaptation mechanism starts a proxy repository on host 5 . The initiation of the proxy repository and the strategy for loading objects from the central repository to the proxy repository depends on the architecture of the proxy repository, which is covered by the following section.