5.Description Examples

Here we will introduce an example using D­case description steps.In DEOS an annual demo is held at ET(Embedded Technology Exhibition in Japan).



Fig.6 illustrates a web server system which was demonstrated in 2011.Let`s write a D­case for this system.Here we will use a description experiment conducted by the DEOS center.

1.Define the system life cycle, summarize input-output document of each phase
This web server system was developed by integrating existing server PCs.Fig.7 illustrates its life cycle and input, output documents.However, since it is a demo system there is a possibility that some of the documents do not actually exist.Here we will focus on the operational work-flow definition document.



2.Categorize input, output documents
Input, Output document of each phase is organised and categorized from the dependability viewpoint.This becomes an input when writing a D­-case.

3.State a top goal : “the system is dependable”
The top goal of D­case is a claim that relates to dependability of a system.First we put the sentence "the system is dependable".Then, change and elaborate according to the targeted system.In this example we assumed, "the web server system sufficiently satisfies the SLA (Service Level Agreement)".