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This section will highlight some of the functional characteristics necessary for the design of an access mediation or access gateway applications platform.
Highly Flexible Applications Development Environment
The candidate platform should be flexible enough to allow the application developer to utilize the functions necessary to implement access mediation/access gateway applications. For example, the developer must have access to almost every protocol and message set. In addition, the developer should not be restricted in the type of transactions that the application can handle. The platform requirement transcends merely accepting queries and sending responses. In access mediation/access gateway applications, queries must be forwarded from the mediation point, and the mediation point must initiate new transactions.
Access to Multiple Protocol Sets in the Same Application
The platform should enable a single application to utilize multiple protocol sets. This allows for a protocol gateway to be created. As shown in Figures 3 and 4, this is the fundamental application of access gateways. In order for different networks to be interconnected, the ability to provide a gateway that converts the different protocols is essential.
Ability to Handle Complex Transactions
Most SCP platforms have been designed to handle basic transactions. In other words, they have been designed to accept a query and send a corresponding response. However, for access mediation/access gateway applications, the platform often handles complex transactions. For example, the platform must be able to forward or relay messages. The platform must also originate new query transactions and correlate the associated responses. Call or transaction state information may need to be maintained, and persistent storage mechanisms may need to be provided.
Overload and Performance Management
It is important that the platform be able to determine an overload condition on a per service basis. This is useful for transaction and quality of service monitoring. For example, if an overload condition is reached, the platform should be able to determine the offending service. As a result, the overloading service can be throttled independently, instead of throttling all services on the platform. This capability enables networks to handle overload and performance management separately.
Flexible Measurements
For access mediation/access gateway applications, measurements collection capabilities beyond those provided by basic peg counters are often needed. Usually, a more flexible collection and measurement system is required. For example, if a report is needed to determine the number of queries on an originating point code basis (where the point code will identify the system accessing the mediation point, possibly for billing purposes) this must be accomplished. One approach would be to collect information on individual transactions and later aggregate this information into custom reports.
