The purpose is to find a general definition for robustness examination of web site design system through the development process. Research presently robustness options and analysis explanations, most of them are being used for large software development or os's. Then considers one of currently definitions which might be best suited to robustness of web site design, Failure Methods and Effects Analysis to identify and measure the robustness of the web system which is predicated on the Jacobson''s research method that models the components of web site design system.
Keywords: Robustness Jacobson research web design Inability Modes and Effects Analysis (FMEA)
Along with information technology, especially the rapid development of computer technology, remarkable changes in the network age brought websites have surfaced. On the other hand, there are many reasons can lead to web site does not work. Systemically, it makes very difficult to check all problems. However, when site is designed, to use a measure to evaluation a variety of problems which might lead to crash web site is very important. Not merely can increase the robustness of the web page, but likewise have the ability to cope with some unforeseen situation, in order to make the website more secure and solid.
In computer technology, the clear description of robustness is not easy to be given, particularly when it is observed with trustworthiness . Nonetheless it has ability to deal with errors during execution of a system.  It can be regarded as way of measuring criteria, apart from basic properties such as protection, stability and functionality, the robustness of overall internet site is also important. Along the way of web site design, there is certainly some robustness of steps to be reviewed in order to enhance overall site, in other words, it still can keep steady execution if some components of website do not work in unexpected circumstances.
2. Main Part
2. 1 What is robustness?
There are some explanations of robustness have to be mentioned first. When the term ''sturdy'' used in computer knowledge, adverts to computer applications that shows not only under typical conditions but also under unusual conditions that emphasis expectation of its designers''. Productions created by computer such as internet sites are typically buggy (i. e. include problems) and fragile, therefore not powerful. It is problematic for a programmer to find and fix all the mistakes.
Second, you can find one beautiful way to distinguish consistency and robustness, the way is to check out the types of mistakes. From the point of view of web design, stability problem is often triggered by internal mistakes in website or part. Robustness problem is often brought on by external mistakes, such as unpredicted insight.  After making clear both of these principles, for the features of mistakes of robustness can be developed related measures.
2. 2 Explanations of measures for robustness
The success criterion is generally:''if the machine will not crash or hang up, then it is sturdy''.
 Fuzz screening is a straightforward technology that has far-reaching result to quality of the rules. In fuzz assessment, it generates bad data randomly to attack an application, and then programmer observes what breaks. The approach of fuzz evaluation is the fact, it is illogical, automated test and will not speculate which data will lead to be harmed like manual evaluation. Instead, test muddle of the application form data deeply as much as possible. The end result maybe leads programmer surprise, because any reasonable thinking person would not think of that kind of errors. It is simple, but it can declare the important pests in the application.
How will it work?
Realization of fuzz testing is very simple process.
1. Prepare a correct file and insert it in this program.
2. Generate arbitrary data to replace some elements of the file.
3. Observe what breaks.
First, generally, fuzz assessment only finds very easy errors. Second, the bugs found severe sometimes, because fuzz assessment is very popular on the globe, real attacker can use the same tool and develop other damaging programs. Third, the randomly inputs to get a boundary value condition is difficult.
Ballista is an method of make the operating system crash to get exceptional guidelines and the guidelines are used for system calls, then to make other software get abnormal termination instead of denoting problems gracefully. It is a ''dark-colored box'' screening. The goal of the Ballista is to check the robustness of the prevailing components. The results will apply as a course to an array of software components. But generally, the best situation is that, focus on modules which take all inputs from a parameter list.
How does indeed it work?
Ballista approach starts off at bombard an application component with combinations of exceptional and unexceptional source values. The response of the system is assessed for ''severe operating system failure'', an activity ''hang'' or a task ''abort''. ''Severe Operating-system failure'' is generally by means of a machine reboot, ''hang up'' is detected with a watchdog timer, and ''abort'' is detected by inspecting abnormal termination of a kid process. Ballista runs on the set of test conditions and runs a sizable number of these inputs.
Ballista is an extremely successful testing procedure, but it is often used in operating-system, not in web design. It also needs specific drive as workload to call kernel function. Therefore it is not easy to be extended.  Another disadvantage of Ballista is that it's very difficult to create test instances because the valid and invalid test data both must to be generated by type generator.
JCrasher is an method of test robustness of Java program. It inspects the type of java course and constructs code fragments that will create cases of different types to test general population methods under arbitrary test data. It can be used to examine pests caused by this program, if the program crash, it will throw an undeclared runtime exception. It does not require regulation except for offline tests of the situations which have brought on a crash.
Drawback: The rewrite of classes is re-initializable, and they could exist in another compile phase, rather than at weight time. It really is a drawback because JCrasher will not support dynamic launching.
FMEA (Failure modes and results analysis)
Failure methods and effects analysis (FMEA) is an operation for research of potential failing modes within something for classification by severeness and odds of the failures. It really is developed in three main phases which are severity, occurrence and recognition. They determined the grade of robustness of the machine. Before starting to utilize EMEA, the top work needs to be achieved first, is that confirms that robustness is roofed in the research.
1. Examination and improves the safety, reliability and robustness of something.
2. Reduces the potential for robustness concerns.
3. Detects, recognizes and removes of potential problems early.
2. 3 New idea in web design
Robustness concerns surprising domain. To improve robustness, procedures should be taken either expand the opportunity of specification, or make sure stableness of system under unpredicted situation. FMEA might be most appropriate of calculating robustness to web site design. Since it can be utilized for robustness evaluation of the specification of web design, and the results can be specified, therefore designer can clearly understand the problems and find related solutions. Alternatively, fuzz evaluation and JCrasher are hottest in large software development, if the program writing language of web design is JSP (Java service webpage), JCrasher can be used for measuring the robustness of java parts during web growing. Ballista is normally strongly found in os's. The robustness of website is vital. Because  web system evaluated through the HTTP standard protocol, it is difficult to regulate the suggestions of users. The net system will need to have tolerance to unpredicted problems from users'' insight.
2. 3. 1 Preparatory work
Before applying FMEA, there are two essential works needed. First is to model the robustness of components for web design. Second is to design the worksheet.
2. 3. 1. 1 Model the robustness of components :
One of the greatest ''use circumstance diagram'' method is Jacobson''s research. To design a powerful web, model the procedure of web system before develop rules is vital. Here, it is employed to analysis produced web product,  there's a diagram for robustness diagram design.
The diagram is coupled with class diagram and activity diagram. The part of the distance is robustness diagram. There are many features. It can be used to help creator to guarantee the correctness of use case. It can be used to ensure use circumstance to contain all the necessary branch of the process, in so doing providing the correctness inspections. It can be used to reduce the gap between research and design, and then in the end complete the primary design.
The Jacobson''s use case diagram uses three stereotype elements :
1. Entity subject, usually it is from real life, classes from the domains model.
2. Boundary object, it is used to interactive between users and system. Normally, it contains frame, diagonal, menus, and they're typically displays or web pages.
3. Control thing, it is utilized to hook up boundary thing with boundary object.
Boundary subject and entity thing are nouns (objects) and controller is verb (action). And there are four interactive guidelines for these three stereotype elements when design robustness diagrams.
1. Nouns can connect to verbs (vice versa)
2. Nouns cannot connect to other nouns.
3. Verbs can connect to other verbs.
According to these rules, any aspect in web design can be designed as a robustness diagram. For example, if the part in web design is web login system, developer can bring the diagram and evaluation the working control for the existing component of the system.
Generally, it isn't hard to find ''home webpage'', ''background login page'' are boundary objects according to evaluation above text useful case. And the system provides input checking (in branch process), thus ''looking at'' is controller object. System can shows error meaning, therefore ''display'' is another controller thing. System will search the databases to find the information form of the user, ''users'' information form'' and ''individual information'' is entity objects, ''initial end user information'' is controller thing. Finally, the robustness of case is shown below.
Once creator has done robustness analysis, they have to do a Initial Design Review . The period of Initial Design Review helps developer to ensure that robustness diagrams, domain name model, and the utilization case word all match to one another. After robustness examination, the designer could continue to next step of in depth design, and writing rules for it.
2. 3. 1. 2 Design the worksheet:
When the robustness diagram is research, then creator could create worksheet to continue the analysis and solution, worksheet provides the important information about the machine. All the items or functions of the worksheet should be outlined in a reasonable manner.
The purpose of FMEA is to explore all possible failure modes of each control object model from the exterior operating environment (e. g. user input), the probability of detection possibility, and the severity of the impact to the robustness requirements of web system. In addition, it can be used for every single control objects. Results are usually launched in a specially designed worksheet.
Example of FMEA Worksheet for login part
Control subject Failure function System Impact S
(Severity score) Possible Cause(s) O
(occurrence rating) D(detection rating) CRIT
(critical characteristic) RPN(risk priority amount) Suggested actions
Login control No response is produced at all Fail to respond to user''s connections. Prevent further use of the machine. 8 Error user suggestions/ database is made up of inappropriate/damaged data 2 5 N 80 Control the user input, and also to prevent serious problems into the thing.
Understand some variables of the stand. 
''S'' is Intensity score of the crash effect, 1 means no risk, 10 means critical.
''O'' is incident rating, similarly, the range of it is from 1 to 10, it is based on the web design specification
''D'' is detection rating, the value of it means the power of identify the failures.
''RPN'' is risk priority Quantities, it is computed by formulation RPN = S x O x D. The highest severity of the failure mode may not actually to be treated firstly, but rather the best RPN should be treated.
RPN can be seen as a metric of robustness for the machine, and the robustness will be better if creators solve highest RPN.
There are several goals can be achieved:
1. Classify the robustness critical elements, that is, the part of program logic which is straightforward to failure or crash from external errors or unusual situation.
2. Ranking main concern to the possible reasons causes of failure robustness.
3. Establish prevention options, either eliminate possible causes or decrease the effect of web robustness.
Seldom methods to analysis and way of measuring robustness of web site design. FMEA could build the requirement to minimize the probability of failure in order to improve robustness of the web system. And it can evaluate how the component of the net system might fail and how the failure influences to the system functions. Nonetheless it cost much time to analysis the net product, because each component of the net product must be analysis. But it ensures the actual errors will not affect the whole web system. Although the technique is based on the foundation of useful applications, but it generally does not often apply to a genuine development process. The numerical evaluation system of robustness will make the effect clear. FMEA can be utilized both along the way of web design and developed web product. For a sizable web product development, FMEA might be appropriate solution to analysis the product.
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