PRELIMINARY STUDY

Phase PS.3 Generalization

PS.3.1 Purposes

This phase closes the preliminary study. It allows to pass to the logical level and already taking the main physical constraints into account.

 For every selected solution, generalize by taking a greater number of cases into account, and no longer only the 'normal representative cases'

 Go deeper into the study of the impact on the organization

 Evaluate with care the economical impact (required resources, costs, benefits)

 Evaluate with care the impact on the migration (planning, resources, ...)

The purpose is to become able to make the realization decision.

PS.3.2 Realization actions

 Functions

 Take the other procedures into account (special cases, ...). Extend the solution from the limited framework of the normal representative cases.

The cases that are completely exceptional or abnormal need not being managed fully by the system; nevertheless, they need being processed by an exception procedure to be defined.

Think to the possible exceptions in the e-business application. An exception procedure for an e-business system could be a toll-free phone number or a mail contact.

• customers with singular needs could feel themselves lost.
• some customers can misunderstand the application use
• in some circumstances, the web application can work in a way that was not foreseen

 Processes

 Describe the logic of the processes. Several logical scenarios are possible for one functions set.

Describe the processes sequences.

Describe the actors and their responsibilities; propose new organizational models.

Who does what ? The tasks groups should be allocated to services.

Logical Processes Model
Procedure: online purchase orders process
Day	Operation	Who	Process
			man	IT system
D0	Products selection	Customer	enter	assist
D0	Enter payment	Customer	enter
D0	Transaction commitment	Customer	confirm	availability validation payment validation payment registration order registration
D0	Transaction confirmation			send a confirmation email
N0-night	Packaging	Dispatching	manual packaging
N0-night	Delivery taken in charge by a third company	Carrier	deliver

 Describe the logic of some functions (flow chart, rules, ...)

  Screen models can be useful tools to help understanding the system.

 At the data level [Logical Data Model]

 complete the data and information inventory.

 complete the conceptual data model by adding

actors, access rights, data protection ...

historical or last value ?

 describe the different possible states of an entity or of a data group

Entity Life Cycle Diagram

 Take the technical (physical) aspects in charge.

 physical implementation

Describe the IT system: study all needed resources

distribution of data, tasks and processes

security: plan to set up the web server on a standalone machine

smart failure: plan to duplicate every hardware architecture component

peek performance: plan to cluster many servers

constraints linked to hardware, operating system, network, ...

Resource pooling : some resources, e.g. connections to services like a database or an ERP, are expensive in terms of allocation (instantiation) time and memory. It is not possible for every online user to have its own resources : they have to be shared. Generic customers should for instance share a few database connections on the "generic customer" account.

include this requirement for the selection of both the object framework (i.e. OLE/COM or Java) and the merchant software package.

Ethernet segment isolation : network connections between the http, processing and database servers should use a dedicated Ethernet segment (high traffic expected)

 

security policy

plan to install a firewall on the web server

plan a detailed security study

plan to clearly separate development and production environments : they should run on different computers 

 identify the main risks factors at operation time.

 backup / restore

 degraded operation mode, accepted time limit, ...

Provide a bandswitch limiting mechanism : users should be redirected to a « waiting area » if the servers are overloaded.

   Web site technical architecture

   Web site hosting / management

 Evaluate the impact on the organization:

 evolution of the services and of the hierarchy; study the changes in the workload and in the required human resources; study the trainingand outsourcing requirements

PS.3.3 Project management actions

 Integrate all practical constraints (complete the functional aspects)

constraints linked to existing equipment

compatibility constraints

portability constraints

operational constraints

 Integrate the quantitative data

traffic volume, upstream and downstream

data volume 

processes volume, transactions number.

users number

expected response time

 Set up the migration to the new system

Integrate the migration constraints

Try to merge purposes and constraints coming from the system architecture design, and technical and human constraints.

Set up migration scenarios.

 Set up the final balance of the selected solution in terms of:

 costs, needed resources

  Human resources:

Make an inventory of the needed project tasks and quantify them

Assign the project tasks to project functions

Evaluate the skills required to perform these project functions

 benefits

 planning

 risks

PS.3.4 Quality assurance actions

 Control by second reading, simple or alternate.

 Key factor; UPSTREAM: check that all requirements find a solution

 at the functions & processes level

check systematically that all requirements from the preliminary study will find a solution

evaluate the requirements that would not find a solution

the possible limits, particularly in organization terms (automation level).

 at the data level

make sure that the data inventory is mode under a systematic form .

this inventory can be the base for the specifications, the tests games and the basic customizing.

 at the resources level

make particularly sure that all human resources that will be required during the detailed analyses, realization and launch steps will be effectively available.

 Key factor: focus the quality control as from now, in order that the preliminary study is the base for the evaluation of the final realization.

PS.3.5 Phase closing actions

 Write a summary report of the preliminary study, allowing the decision-makers to choose.

 At the end of this phase, all the aspects of the new solution should be well known and the decision can be made with a full knowledge of the facts:

detailed description of the new processes.

new work organization; required human resources

new architecture; realization budget.

evolution scenario: feasibility, planning, cost

economical balance

 Needed resources

The budgetary constraints should be added to the technical constraints and the ones coming from the System Architecture Design.

The project may be cut in sub-projects.

 You should inform widely about the conclusions of the preliminary study:

all the people who participated to the preliminary study

all the people who will participate to the detailed study

the management