The Enterprise Architecture Repository is both a means to store all of the artefacts concerning the enterprise architecture and a federated information system linking with other sources of data and c0ntent. This federated environment produces a enterprise architecture management system to support architectural development. There is quite an interesting overview of this on the Aris Community blog.
Along side the standard features of the repository, to hold the information pertaining to the AsIs and ToBe models, is the need for the system to support research development and evidence management. The enterprise architecture is represented by a collection of facts and statements about the enterprise. They are collected in a set of artefacts and are used through the architecture development methodology to build future versions of the enterprise. It is the change from the current state of the enterprise to a new state that evidence is required and applied to support change decisions. The evidence that is used and cited within artefacts it should be stored within the architecture repository. This enables the evidence to analysed and tracked through the lifetime of the decision.
The evidence repository is a subset of the EA repository or federated knowledge base that has defined relationships that link the evidence to the artefact. This can be achieved through simple hyperlinks but a defined approach with specific artefact metadata and unique identifiers would offer a structured relationship. This should also encompass the evidence metadata to provide the attributes to support tracking such as the value, confidence and temporal attributes.
Whilst it is important to store evidence cited within artefacts within the EA repository it is also important to store research and information to act as future evidence. This form of evidence should be built with a formal process and should be collected in line with future views of the organisation. This type of evidence can include horizon scanning of new technologies, customer or user opinions and surveys, planned legislative changes or innovations.
I have made this principle 1 because i consider an enterprise architecture repository a fundamental part of enterprise architecture and building up and storing evidence is a vital part of evidence based enterprise architecture.