EIS InfoBook Multi-[name] description, undated

NYC 9/11 Public Portal Document

client has direct access to the database and, based on each individual user’s permissions, can directly update data on the server. This can lead to two drawbacks: a large number of people accessing a single server can degrade performance and everyone is connected to, processing, and updating the ultimate source data which can result in a risk to the integrity of the data. To counter these two drawbacks, the next type of architecture is available, data warehouse.

Data Warehouse Architecture

A data warehouse is a server, like all other servers in a client/server environment. Its purpose, however, is to be a repository for data that is viewed, not acted upon. As Figure 3 shows, the data warehouse server is directly connected to one or more other servers. This may be in the form of updatable views or standard database replication. The net result is that a client can access either a server that contains a subset of information or the data warehouse server which contains a superset of information. The difference is that, in general, a site will have permission to make maximum use (read, update, etc.) to its own server whereas its access to a data warehouse server does not allow the update of information. The data warehouse represents an integrated view of clean and analyzed data rather than the raw data that would reside in the other servers.

EIS IntoBook's use of data warehouse architecture is ideally suited for those central or headquarters offices that need to understand, but not act upon, information processes taking zMitiinaiTim

place at remote sites. This concept of different users with different needs for information processing being served by different information processing capabilities and architectures gives rise to the next type of architecture, multi-tier Figure 3 client/server architecture.

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