City Planning Use Context
City Planning Objectives
The main objective of city planning is to enable the information system to evolve progressively, without having to redesign the entire system, while allowing programs or software of different origins and periods to peacefully coexist.
For this to happen, it is necessary to define information system design rules that are valid for many years and are therefore independent of changes in technology.
City planning assumes that inventory of application assets has already been established, but it is not necessary to have documented the application architecture in detail; only the names of the applications and services is required.
A second objective of city planning is to identify functional redundancies in order to:
• Avoid creating new systems when developing new applications by using existing software resources.
• Reduce maintenance costs by carrying out renovations block by block, defining a new resource that is substituted for old ones and satisfies the various use cases.
• Consolidate two Information Systems in cases such as a merger/acquisition.
• Prepare the deployment of EAI software on a large scale.
Note, however, that certain redundancies are justified. The fact that two use cases are similar does not necessarily imply that there must be a single solution. Other constraints (operation, performance, etc.) may lead to keeping them separate.
City planning justification
City planning is justified for businesses:
• that have significant application assets.
• that have a long history in information technology.
• where information technology is strategic.
It may also be justified in:
• Mergers/Acquisitions
This immediately results in a high level of redundancy, particularly in operating resources. The city planning must occur prior to consolidating IT resources.
• Enterprises dependent on "software packages"
Here again, the level of redundancy may be significant, particularly in the data. The objective of city planning is to prepare for data synchronization
Apart from these cases, city planning projects are rarely flagship projects. They must be low key, with no negative impact on other projects.
City Planning and Application Architecture
The application architecture defines or documents (maps) the structure of applications and their services, showing the cooperation between them. It explains how the information system functions.
The city planning for the information system explains what the applications do, documenting redundancies so they can be reduced.