Future Work

Given the dynamic IoS setting, an ever changing application scenario can be foreseen for the BabelNEG infrastructure. In this last section, I will shortly sketch what adaptions / extensions to the current system design could be introduced in order to increase its overall adaptability to such new application settings.

The most fundamental dynamics, which can be anticipated for the future IoS, are a changing set of services and service metrics; especially in case of an ongoing trend to automate individual business functionalities and the emergence of juristical foundations for cross-organizational automated service transactions. This development can already be captured in the current system architecture, as it only affects the service vocabulary used within the negotiations. The actual agent roles, messages and negotiation protocols in general do not differ just because the negotiated metrics change.

Similarly, optimization of negotiation strategies with regard to a) individual nego-tiation protocols or even b) when introducing strategies optimized for a whole set of different protocols (which would be favored by a protocol-generic approach as presented in this thesis) does not affect the system architecture and communication mechanisms designed therein.

If more sophisticated negotiation protocols emerge, an extension of the description documents proposed in this thesis could become necessary. A potential adjustment, in-creasing their expressiveness, could be the introduction of sub-states within the negotia-tion process. This would result in an altered process-element within the EST document;

not only the incoming event will determine the possible actions, but rather a tuple of in-coming event and current state. This results in a direct equivalence to the state machine paradigm.

Apart from these dynamics of the underlying scenario, some fundamental extensions could be introduced, increasing the general efficiency of BabelNEG:

The first potential extension would be the introduction of a dedicated Information Service role, responsible for distributing negotiation-relevant data². Which data can be accessed can already be described within the EST document and in the current infrastructure proposal the NC is assumed to distribute such information. However, a comprehensive support for information distribution, potentially allowing for protocols,

2In the current prototype, this aspect was considered out of scope, as the primary goal was to investigate the adaptability of the SCs to new protocols.

in which the negotiating agents have to actively request some information, on e.g. the current highest bid during their negotiation behavior, is still to be designed.

Also, a publish / subscribe system could be another interesting extension to my system.

It could build on the already used query data structure (used for querying SIs, ESTs or STs from the RA at the moment) and would allow a SC agent to post the need for a service of a given type (and / or offering a given protocol) whenever no such service could be found right away. To this end, it would define the search criteria, create a respective query object and post this interest to a RA. Whenever a SI fitting the stated query is published at the RA, a notification message is sent to the respective SC, indicating that an instance of the required service is finally available on the market.

In order to assure timeliness of the stored interests a lease-based mechanism could be employed. Each interest, registered with the RA, must be renewed after certain time intervals. Whenever a lease is not renewed in time the respective interest is deleted from the publish / subscribe infrastructure.

A minor extension to the current system could also allow for the integration of reverse negotiations (and thus eventually for protocol-generity, or the need for such, at the SP side). Instead of publishing SI documents, representing a service offered by a SP, the SC agents could offer an extended SI document representing a demand for a service, the respective SC currently needs. This demand document would exhibit the same internal structure as an SI. However, no link to a WSDL document would be present, as the actual service implementation fulfilling this demand (if any of such is ever found), is not known at publication time. Additionally, the EST to be applied for this demand is only optional. If existent it denotes that the service to be found must not only fit the stated ST but also adhere to the stated EST (i.e. a distinct protocol is requested), if not, only the type of the service is specified as a criteria in the demand.

Especially the discovery architecture is very basic in the current version of the sys-tem. This is due to the already mentioned pragmatic reasons. Future versions should incorporate a more sophisticated and thus more robust and scalable discovery mecha-nism than a single registry node. The most promising approach for this is probably a P2P-based architecture, given such systems excel in scalability and resilience to node failures (especially structured ones).

One idea to integrate the current prototype with a P2P-based discovery architecture is to introduce a DHT which connects all registry nodes and in which all service description documents are stored. Whenever a service request is submitted to a registry node (node within the DHT ring), the respective documents are retrieved and returned to the requestor.

A new RA can simply join this system by discovering a DHT node already present (broadcast discovery) and then join the DHT ring as a neighbor of this node. Internally, this results in the re-distribution of the stored data and routing information. In contrast, the absence of a RA (which has left the DHT) is directly noticed by its neighbor, which then triggers the re-arrangement of the DHT data accordingly (this represents a standard mechanism for DHTs).

All of these extensions could help to increase the efficiency and overall functionality of the developed system. Nevertheless, the prototype as currently available already

demonstrates the feasibility of automated protocol-generity in SLA negotiations, which was the primary goal of this thesis.