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System Design Examples (InSeKTs)

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And then we have been discussing about another example on another system designbasically a known as InSeKTs. Basically, it is a Institute Service Kiosk Terminals. So, wediscussed about the objective of these particular system, and what are the basicrequirements, and how do we identify the requirements through scenario analysis, andinput output trace and then we discussed about the requirement identification and how dowe develop the originating requirements document or ORD.So once we have this, we discussed about the context diagram and then what are theexternal systems associated with remain system. In the next task is, basically to go andanalyze the functions of the system or we go for a functional decomposition.So, as we explained in the previous lecture.
(Refer Slide Time: 01:37)
The system context diagram is shown here. So, this is the system or we have manysubsystems and external systems acting or used in the main system through the contextdiagram shows the GPS system as an external system then other service providers isexternal system user as an external system. And then the server and database as externalsystems and of course, all other peripheral devices also.(Refer Slide Time: 02:06)
The main objective; we already explain that it is basically to provide the services for thevisitors as well as to the students. So, in order to do the functional decomposition we use
the method IDEF0 when we discussed about functional decomposition. So, IDEF0 is adiagrammatic method of decomposing the functions in to sub functions. So, here wehave different diagrams like A 0; A-0, A 1, A 2, A 3 like that. So, A 0 is the contextdiagram.So, here in this diagram we will show the system as well as it is external systems and thecontext in which the system is being used. So, the main function we can say providedirections and other navigation details to the visitors of course, you can have additionalfunctions also, but here we show this as the one of the main functions and then what arethe external systems and interactions needed for the system are shown here in the contextdiagram and then InSeKTs the main hardware which actually provides you this function.So, this is the context diagram or A0 diagram and then we try to decompose this functionor this diagram into sub functions. So, we start with this main function provide directionsin other navigation details as a main function and then decompose this into sub functions.So, when we decomposed we will be getting the A1 diagram this is the review of theprevious diagram; so for better clarity shown it as a separate diagram. So, here you cansee this is the main function provide directions and other navigation details and then youhave the hardware which actually provides this meant for service and then you have themaintenance services and maintenance system as an external system and you have allother external interactions and eternal users the different types of users then the userrequest different kinds of request and then there are destination information and thenrequest from customers.Similarly, the output from the system as acknowledgement and then location detailsnavigation details and then print out. So, these are the outputs these are the main inputsto the system now we will try to develop it further or we will decompose this functionfurther using IDEF0 methods.
(Refer Slide Time: 04:31)
So, we will go for the A 1 diagram which actually shows the sub functions which can beidentified from the A 0 function. So, the A 0 function is decomposed into 4 mainfunctions here as you can see accept request process request search database find routes.So, these are the main 4 functions which can be identified from the A 0 function. So, theA 0 function is decomposed into 4 functions here and then you can see the type ofinteractions taking place between these functions and the inputs coming to thesefunctions as well as the output from this function.As you can see, the inputs are basically the user request then the power supply in thedatabase and other infrastructural supports and then you have the output as acknowledgerequest then the display directions and the print map depending on the request from thecustomer we can actually provide a printed map or other kind of output. So, these are theinteractions taking place. So, it is not only the interaction with outside systems basicallywe will be having lot of interaction within the systems also within the sub functions alsothere will be many interaction. So, the output from this will be going to the processrequest that the request will be processed here and the process request should be sendingthe data to the searching database function.So, here the digitized request will be passed to this function and then the output will bepassed to the find route function. And then finally, the output will be given from here.So, these are the 4 functions which can be identified from the A0 function this is shown
with more clarity here in this diagram it is the same diagram which I explained earlier,you can see here this is the accept request function with the user request for directionsand the input power supply as the inputs. And then you have this output coming fromhere to the process request function where the digitized request will be going to thesearch database. So, here the output will be acknowledgement of the request then thesearch in database then find possible routes and that route will be displayed as a output tothe customer.So, these are the 4 main functions we can identify from the first function. So, thisdiagram is known as A11 diagram. So, here actually we are decomposing the A 1function into 4 functions now all these functions can be decomposed further into smallfunctions. So, we take one function here and then try to decompose that into smallfunctions. So, we can take accept request as one function A11 function and then we willdecompose this A 1 function, then we will decompose this into sub functions. So, that isshown here the accept request function is decomposed into small functions here. So,these the accept request the first function then digitize request is the next function in thatone and then once you have the digitization of the request, it will be passed to the nextfunction this is basically acknowledge request.So, there is another function to provide an acknowledgement or the output to show thatthe request has been accepted and that will be giving the output to the main to the nextfunction with or actually the output will be shown as a display or as some kind of afeedback to the customer. So, these are the sub function which you can identify from theA 1 function. So, this is A11 diagram. So, it will be having 3 sub functions here accept
request digitize request and acknowledge request same way we can actually furtherdecompose this into small functions like this we can actually decompose all thesefunctions into small functions and then we can get complete functional decomposition ofthe system.So, once we have the complete decomposition of the system we can actually develop afunctional decomposition at chart. So, functional decomposed in chart is an output of theIDEF0 a diagrams. So, we will take at the functions identified in the IDEF0 diagram andthen represent them as a chart as a hierarchical chart that will give you the functionaldecomposition. So, once we have the functional decomposition it actually tells us thatwhat are the functions to be provided in the system as we show in some of the previous
examples, we can actually write down all the functions like accept request digitizerequest acknowledge request like that and that will provide you an hierarchy of functionsand based on this functional hierarchy we can actually develop a physical architecture.As I mentioned earlier there are 2 types of physical architecture we developed one is thegeneric physical architecture the other one is the instantiated physical architecture in thegeneric architecture, we will identify the generic components to provide the functionsand in the instantiated one; we will try to give the details of these components whichactually can be used for that particular function.(Refer Slide Time: 09:59)
So, what we are shown here is a generic physical architecture for the InSeKTs system aswe can see there are multiple sub functions we need to provide in the system and notshown the complete diagram here because of the lack of space in to show the holdstructure here. So, we can see the user interface is one important sub function whichactually provide you input and output from the system.So, that is one sub functions of for that we need to have a user interface. So, userinterface components is one then the GPS and navigation aids and communicationmodule then power module than other input output modules also will be there. So, hereagain for the user interface we can see that there are different kinds of inputs and outputrequirements. So, we can use keyboards or touch screen telephone speaker display screenprinter fax. So, these are the component which can be used for the user interface
similarly for GPS and navigation aids we can see there are receiver transmittersprocessors and database server as the components for providing this particular functionfor communication module again we can have a network components and other hardwareand then of course, you can include the software also for communication.Then power module also we can have the normal power supply or the battery powersupply as the additional components over here. So, like this we can develop the genericphysical architecture. And I, now to get the instantiated physical architecture we can gofor the morphological box and identify the components which can be used for thesepurposes and we can see what kind of actual component or what device need to be usedfor these purposes. So, that is the next task. So, we can go for morphological box andthen get the details.(Refer Slide Time: 11:48)
So, here again we have different options I am just showing a very simple example hereyou can actually go for all components you can have actually developed themorphological box.So, here I have shown the display the telephone and the network options as well as theprinters and the direction are showing options and the database options the networkoptions.
(Refer Slide Time: 12:08)
(Refer Slide Time: 12:19)
So, here there are taken few components and then developed the morphological box asyou can see for the display you can have a different kinds of monitor CRT, LCDelectronics or plasma display or touch screen display and for the telephone you can havea cordless phone or with the code or with the our mobile phones you can have a networkvarious existing network and we have chosen or you can have a dedicated network forthe system can have different kinds of printers ink jet or dot matrix for the directions youcan have different databases or we can have the already existing softwares or algorithmcan be used for this purpose.
(Refer Slide Time: 12:57)
And the database can actually be again chosen from the existing database or we candevelop our own database and then local area network can be opted based on differentoptions available.(Refer Slide Time: 13:05)
Please discuss about the ring or master slave or architecture. So, we can actually chooseany one of this architecture for the network. So, like this we have different options andbased on this morphological box you can choose component for input output as well as
the directions and navigation and that can actually be shown in the architecture, then itbecomes a instantiated physical architecture.(Refer Slide Time: 13:34)
And apart from this requirements identified will be having redundancy requirementsbecause of the fault tolerance. So, we need to have methods to prevent the faultspreading to other parts. So, we can have the various kinds of fault detection method. So,we can actually have fault detection for the following cases were the user or supportfeedback system fails or the access to printer or fax telephone fails power supply systemfails or transmitter fails. Of course, you can identify many other scenarios also and try toprovide the redundancy requirement for these cases.
(Refer Slide Time: 14:10)
Here I have provided few cases basically for when the transmitter fails or from thesatellite GPS data fails and we need to have a hot standby system or hot standby sparingsystem can be provided to get the signal from the satellite.(Refer Slide Time: 14:21)
So, we can actually have transmitters more than one transmitter to transmit the signalfrom the satellite. So, we can have them in the cold stand by the hot standby is basicallyall these transmitters will be in on condition and there will be an error detector in this onewith the specified error declared here. So, based on that this will declared whether there
is an error or not if there is an error in this particular transmitter then automatically dataone from this transmitter will be accepted by the control unit and the control unit willgiven output to the system here.So, based on these the data will be accepted. So, depending on the health condition of thetransmitter the; whichever the transmitter is in good health condition will be used forproviding the data. So, that is the hot standby sparing methods.(Refer Slide Time: 15:16)
And similarly for the support of feedback system fails. So, we can actually havetriplicated TMR kind of method over here.
(Refer Slide Time: 15:22)
So, when the feedback system fails. So, we can actually have different ways ofconnecting the user input to the system. So, if one of the method failed other system willbe available for connecting; so the user data; if you are using a keyboard or any otherinterface device; if that with the fails we need to have additional devices to provide theinterface. So, we can actually have them in triplicated TMR model.(Refer Slide Time: 15:52)
So, that any failure in one of the inputs can always be taken care of using these methodsthat is one way of providing the standby sparing method.
(Refer Slide Time: 16:02)
Similarly, for the printer, we can actually have multiple printers in the cold standbymode.(Refer Slide Time: 16:05)
So, we can actually connect to one printer and whenever there is an error this will beactually connected to the printer 2 automatically it will be redirected to printer 2 thoughthe printer 2 will not be in on mode. So, we can actually keep it in cold standby andwhenever needed it can be activated and then can be used for printing the output. So, this
is actually can be in a cold standby because there the time delay in activating this maynot be a critical issue here that is why we can have it is in a cold standby methods.(Refer Slide Time: 16:40)
The same way we can go for the power supply system fail also. So, depending on thetime required to connect to the backup power we can have it in a cold standby mode or ifwe it is very critical we can go for a hot standby also, but in this case even if the powerfails for few seconds, it is not a major issue. So, we can actually connect in a coldstandby we can have a power backup in cold standby. So, whenever the main powerfails.
(Refer Slide Time: 17:12)
We can actually connected to the backup power and then can be used for controlling thesystem or you can actually be powering up the system. So, this is a end its a method ofproviding a standby power supply to avoid any faults in the system or this methodsactually provides fault tolerance for the system these actually shows the weightageallocation of the system.(Refer Slide Time: 17:30)
So, we know that there are multiple requirements for the system and then we need tohave some kind of priority in assigning the task or assigning the system functions.
So, we can actually see that the operational objectives are given the higher priority overhere.(Refer Slide Time: 17:49)
So, 0.65 is given as the priority for operational objectives maintenance is given 0.35. So,this again depends on the designer. So, designer can actually decide which one is moreimportant the maintenance function to be given priority or the operation object is to begiven priority. So, these priority operational objectives can actually be again thepriorities can be assigned to the subtask in the system. So, here again see that are not upto the operational objectives these are the sub functions needed.So, again we saw different methods of calculating the weightages. So, using thosemethods we can actually go for calculation of the weightages for various functions likethe storage capacity the number of simultaneous enquires to be handled speed of datatransfer speed of the system and security for sensitive data ease of use and thisoperational objectives the weightage need to be provided to this objectives based on theoverall weightage assigned to that particular function.So, here operational objective is as given 0.65 maintenance is given 0.35 and again thesub functions in the maintenance are given.
(Refer Slide Time: 19:03)
The weightages based on the importance of those functions. So, this is how we providethe operational objectives to the hierarchy of operational objectives and allocation ofweightage is to various functions. So, this is actually gives us an idea of how the systemdesign starts from the initial identification of operational objectives. And then goingahead with the identification of the actual requirements of the system, then identifyingthe context diagram or developing the context diagram, then looking at the externalsystems, and then input output requirements, then we go ahead with the completerequirement identification trade off requirements as well as system where technologicalrequirements based on that we develop the originating requirements document.And then go ahead with the functional decomposition functional hierarchy physicalarchitecture, then other functions for fault tolerance, then objectives and weightageallocation for various objectives trade off, and then we go for the actual system designdevelopment of the physical components or selection of physical components, and thenintegration of these components.And as we go with this we need to go for the development of testing and evaluationcriteria and then once you have the system we do the testing and evaluation and thenaccept the system. So, that is how we proceed with the design of system. So, all thisexamples, I am not showing the complete procedure and end to end process get this ideaof this is basically to tell you that how to use the principles whatever we learnt in the
system design in a practical situation whenever this is actually a gives you an idea howthis can be used for an real scenarios.So, in order to emphasize this we will take one more exampled again a simple exampledand highlight the importance of various system design principles and use of theseprinciples in the system design.(Refer Slide Time: 21:12)
So, this system is defined as or it is named as UdaReS basically it shows that a unifieddata recording system again, it is a practical example which we developed for a practicalapplication the objective of the unified data recording system is basically to develop aunified data recording system to monitor and control the academic administrative andother day-to-day activities across the campus.Again this is developed for practical application on the campus. So, when we have aunified data recording system which can actually be integrated with various activities ofthe campus then that becomes a complex system where we need to record lot of datafrom various sources like the student attendance the faculty and staff attendance as wellas their salary details, then the type of projects taken up by the faculty and all otheradministrative functions and academic activities like registration of course, this allotmentof a slots to the courses then timetable management registration phd, ms and otherresearch project registrations. So, all these things can be combined to a single systemwhere we can have a single database and the various terminals to record the data and
then it is terminals to access the data at various levels. So, here we are looking for aunified data recording system which can be used for various activities in the campus.We will try to see what are the main objectives and what are the main functions to beprovided and then we go ahead with the identifying the difference sub systems andcomponents in order to achieve the these functions.(Refer Slide Time: 23:05)
So, as I mentioned the main objectives are online recording and compilation ofattendance for students, staff faculty, on a day-to-day basis, real time analysis of slotwise engagement of students or faculty online compilation of student grades and teachercourse feedback integration with the online database of the central library.
(Refer Slide Time: 23:25)
As well as it serves as a real time database for leave salary as scholarship computationmonitor usage of various facilities like mess student facility centre gym swimming pooletcetera by the students as well as staff record faculty student staff usage of commonservices like hospital engineering unit the institute and usage of the data for futuristicplanning.Enable cashless transactions at various camp campus stores. So, apart from the acting asa data storage or recording system you can actually be used as a cashless transactiondevice also when develop an online database for projects undertaken by industrialconsultancy and sponsored research and provide online access to financial information.So, these are the main functions identified for the UdaReS system.
(Refer Slide Time: 24:19)
Now, how do you provide these? So, we need to look at the context diagram and whatare the various entities which will be interacting with the system. So, if this is theUdaReS system, then these are the external system that will be interacting with it. So, wecan see that these are campus services faculty students and staff.(Refer Slide Time: 24:37)
Then a library IC and SR gymkhana and administration of course, the administrationincludes the financial as well as academic activities.
Then the network through which the all the data will be transferred or exchanged withthe different agencies or the subsystems. So, that is the context diagram for the UdaReSsystem.(Refer Slide Time: 25:01)
Now, we look at the U-dare life cycle if you want to develop the system, what will be thelife cycle of the system.
(Refer Slide Time: 25:07)
So, in the development phase that is the main phase where we are looking at. So, weneed to identify the type of devices and I said scanners basically the type of hardwaredevices needed for data entry as well as for storing and the locations were we need toprovide these scanners. So, the type of scanners number of scanners method ofcommunication processing techniques all these things need to be developed in thedevelopment phase.So, this only a few things now we need to go for many more things in the developmentphase like the architecture communication architecture then network architecture allthose need to be developed in the development phase.
(Refer Slide Time: 25:50)
And then it is the assembling or the integration phase. So, we assembled the varioussubsystems to a main system. So, whatever the hardware we identified we try to integratethem together here if any development or new design need to be done that also will bedone, then we will do the assembling of various subsystems and configuring of networksand connecting subsystems to main system in the assembly stage.(Refer Slide Time: 26:15)
Then we go for the testing here testing the working of various subsystems individuallyand collectively to check the process parameters. So, we will run for a few days or few
weeks to see whether the system is working perfectly and depending on the output therefinement of the system will take place and once that is done then it will be deployed foroperation.(Refer Slide Time: 26:33)
So, then this is the deployment phase of the system and once deployed, then it will bemore like the maintenance we need to maintain the system.(Refer Slide Time: 26:46)
So, the maintenance phase requirements need to be identified what kind of checks to bedone what should be the a repair time and recuperation time for a system that is if
something goes wrong how long it will take to come back that is with the MTBF andMTTR and after the maintenance phase basically we will be looking at the refinement.(Refer Slide Time: 27:09)
So, what kind of improvement need to be done. So, there any update to be made andwhat kind of new facilities can be added and what are the features need to be providedfor futuristic expansion. So, all those things will be done in the refinement phase andthen the last one is the retirement phase, we need to see one actually we have to see thesystem can be replaced completely or if it we want to replace what should be the processof a replacement; how do we actually a disposed the hardware as well as othercomponents associated with the system.So, that is the retirement phase. So, when we design the system we need to look at all thephases and then design. So, we will start with the development phase and then we will gothrough various stages of assembly testing then maintenance then refinement as well as aretirement phase we design the system for all these phases. So, we will not be going allthese phases in this example, but I am emphasizing is that it is not only the developmentphase what we need to be worried we need to look at all these phases when we designthe system.
(Refer Slide Time: 28:21)
So, here the scope of the project will be limited to the limited data recording and retrievalby students. So, these are some of the project limitations or the constraints, we impose onsystem. So, the data recording and retrieval by students will be limited that datarecording by all the staff and limited retrieval by authorized stuff.So, all the stuff can actually record the data, but the retrieval will be only limited for toauthorized staff unlimited data entry and limited retrieval by faculty cashless transactionat select establishments and centers only. So, these are some of the constraints weidentified in the early stage of developments here the system operation we look at thescenarios in how to identify the requirements.So, as I discussed or explained the previous case studies we need to look at the variousoperational scenarios in how to identify the complete functional requirements. So, beforewe start the development we look at all possible scenarios and then identify therequirements. So, we can actually go through many scenarios this in the previousexamples also. So, here I will not be going through all the scenarios and explaining howto get the requirements.They will just take one or 2 scenarios and then show how the requirements can beidentified from the scenario.
(Refer Slide Time: 29:39)