EA2T User Manual
Contents
1. EA T User Manual A guide how to use EA2T YO Dept of Industrial Control Systems KTH October 2010 ELFORSK Content EA T User manual 1 Background 1 1 Probabilistic relational models PRMS cccceceeeeeeeeeeeeeeees 1 2 The theory behind the tool ssssssnsssssnsssnnnnnnnnsnnennssnesnennenns 2 Specifying Theory in EA2T DA Sanno EA T aaua a e E ean 2 1 1 Getting familiar with the user interface 05 DAZ Menu Dar nunas aan E EEE ie Zid TOOL Da araen R OO AEE O i Zeiss MO palei E a EA A EAA 2 2 Adding CIASSES iienaa a AE a ES 2 3 PGGING SIO E an a E T 2 4 Addin ADUTE S ia aa a A A AR 2 4 1 Adding Discrete Attributes sssssssssrsnrrnrrsnrrnrenrrnn 2 4 2 Adding Continuous Attributes s sssssssssrssrenrenrene 29 Adding Attribute Relationships cccccccccceeeeeeeeeeeeeeeeeeeeeees 2 5 1 Adding of internal Attribute Relationships 2 5 2 Setting of aggregation FUNCTIONS cccceeeeeeeeeeeeees 2 5 2 1 Setting of discrete aggregation functions 008 2 5 2 2 Setting of continuous aggregation functions 3 Modeling in EA T Concrete Modeler Sf Starting EA Tocana ance tazentsieciauone a a 3 1 1 Getting familiar with the user interface 008 3127 Menu Dares aaa Cadence retsiersincanaral ness crs 3y OO Dal irer ea EA teats OE AE EEE Sadi E Too l E E E A E E E 3 2 Instantiating Classes ruinen A AASA 3 3 Instantiatin2. attribute values as well as that of the causal relations as such Using this analysis framework the pros and cons of the scenarios can be weighted against each other in order to determine which alternative ought to be preferred 2 Specifying Theory in EA T The theory that should be used to perform analysis on is specified with the Abstract Component of the EA2T 2 1 Starting EA T The EA T is written in Java to enable platform independence and thus requires Java JRE to run if missing it can be downloaded at http www java com For windows users the program is started by from the command line using the command java jar AbstractModellerPrm jar Or by clicking on the AbstractModellerPrm jar 2 1 1 Getting familiar with the user interface When starting the abstract modeler the following window is displayed Abstract Modeller c oan x File Help E B g P Add Class E Unsaved Scene Figure 1 The main window of the EAT abstract modeler with modeling pane menu bar tool bar and status bar This view is dominated by the large modeling area the white part of the window Apart from this there is the menu bar and the tool bar at the top of the screen and the info palette at the right side Following is a short description of the menu choices and buttons in the tool bar as well as the info palette 2 1 2 Menu bar The menu consists of two top menus the file menu and the help menu The file menu off
3. automatic easy fashion Bayesian network A Bayesian network is a probabilistic graphical model that represents a set of variables and their probabilistic dependencies Bayesian networks combine a rigorous mathematical handling of uncertainty with a graphical and intuitive depiction of causal relationships between different phenomena Bayesian calculations are at the heart of enterprise architecture analysis using the EA T Concrete modeler The concrete modeler is used to model concrete instances of system scenarios The concrete modeler uses the theoretical framework developed in the abstract modeler to direct and enable complicated enterprise architecture analyses without a need for the user to be a theoretical expert The concrete modeler is mainly intended to be used by enterprise architects in the industry Class A class is a category that entities can belong to When an entity in a concrete model belongs to a class it means that it has some attributes associated with that class as defined in the abstract model For instance the class system might contain attributes such as information security or performance whereas for the class process might have attributes such as efficiency or cycle time Credibility Different data have different credibility depending on whether the source is reliable whether it is recently collected etc When conducting enterprise architecture analyses it is of great import
4. clicking the attribute and selecting Evidence Figure 11 illustrates the display that appears Evidence Evicences for attribute Security Evidence Figure 11 The evidence dialog where John in an interview claims that the attribute is in state Medium with a 95 probability To add evidence on the attribute enter a name on the evidence select which of the attributes states to add evidence about fill in the credibility matrix and press add evidence in the lower left region of the dialog In the example in Figure the evidence John corresponding to the result of an interview with a John claims that the attribute in this case Cyber security policy fulfillment from NERC CIP 003 is in state medium The credibility is 95 a more detailed discussion about credibility follows in the next section It is possible to add multiple evidence on an attribute including conflicting evidence This reflects the possibility of disagreement uncertainty and even deliberate deception All evidence added to an attribute will be Shown in the list at the top of the dialog It is also possible to remove evidence by selecting it in the list and pressing delete evidence Attribute might be updated in case that e g wrong data has been saved This is done by at first clicking on existing evidence Afterwards the evidence is displayed It might be modified afterwards and finally stored through a click on the Update Evidence but
5. equations to be set SO eer Equation For Capacity Equation Press Ctrl space for help Functions and Operations Operations ProbabilityDistribution ArithematicFunctions Trignome tericFunctions yperbolicFunctions Available Nodes Process TimeRequired Figure 16 Properties Dialog for Continuous Attributes The supported functions and operations are shown in the Functions and Operations list on the right and can be added to the equation via either drag amp drop or by hand The attributes of nodes that can be used to create a certain equation are shown in the list Available Nodes If the mouse pointer is over a node in that list the reference slot that a certain attribute is taken from is shown The attributes can be inserted into an equation via drag amp drop too The largest part of this dialog is the box that allows the creation of equations that can be built based upon the already described concepts If ctrl and space are pressed auto completion is performed or the user is presented with possible candidates for completion Finally in the lower part of the dialog the bounds can be set which are used in case that functions are used 2 5 Adding Attribute Relationships As already described above Attributes can be affected by other attributes This has to happen with consideration of the types of the attributes i e only continuous Attributes can be related to continuous attributes and only discrete
6. menu consists of two top menus the file menu and the help menu The file menu offers to Export to XML on the one hand and to Import From XML on the other hand It is also possible to replace or update the existing theory using Apply new Theory this feature is described below The networks which are created during the calculation of the models can optionally be saved Therefore the path needs to be specified using the Save Genie File option Executing the export function creates an xml document that reflects the content of the model whereas the import allows reading a model from xml file which has been created earlier Additionally the program can be closed from the file menu Help I Apply New Theory Save Genie File Export To AML Import From AML Exit Ctrl Q Figure 3 Menu of Concrete Modeller 3 1 3 Tool bar The toolbar as displayed below allows for easy access to the most common functions of the tool O B bead E Add class g Calculate Figure 4 The toolbar of the EAT concrete modeller containing the most common commands Starting from the left there at first the possibility to clear the scene and thereby to start with a new model can be found The second function allows opening of an existing model This is followed by both save and Saves as functionalities A button to add classes is offered next which even allows the instantiation of several classes at a time gt Create M
7. Selection Panel 3 4 Adding evidence Creating instances of classes and relationships builds up the skeleton of the model This provides basic knowledge for performing the assessment based upon prior knowledge about the various attributes i e properties of the model In order for the assessment to be specific for the case at hand this skeleton must be augmented with information about the actual states of the attributes in the model In most cases it is very difficult to have direct knowledge about complex attributes such as the information security of an enterprise otherwise this tool would serve little purpose However more low level attributes such as minimum password length or number of open ports in the firewall can usually be found While this information is generally not hard to find it is potentially very resource demanding to actually gather it all The concept of evidence handles this Evidence is knowledge about the actual states of attributes that is not certain but has a level of credibility that can be taken into account when performing the analysis The EA T concrete modeler allows the user to provide evidence s regarding the states of every attribute including the more complex ones in case such knowledge is available The way evidence is set depends on the kind of the Attribute that is considered 3 4 1 Adding evidence for discrete Attributes Evidence regarding the state of a discrete attribute is given by right
8. Slots so that they are related on each instantiation of that Class automatically The relation is created as all others are In the dialog that is presented the box Internal Reference needs to be checked afterwards 2 5 2 Setting of aggregation functions Aggregation functions describe how several instances of the same Attribute are combined during the calculation The usage of aggregation functions is needed as during the theory modeling the amount of linked instances is unclear i e aggregation functions make the theory prepared to handle dynamic aspects of the instantiations As aggregation functions are used to handle dynamic aspects they are only used when several nodes need to be aggregated This means that in case of only one parent is allowed through multiplicities no aggregation is necessary Whereas if the amount of parents is unclear multiplicity they are utilized To overcome the fact that there also might be zero parents modeled a Default CPT can be set the option is available in an Attribute Relationship s context menu which serves as alternative input in case of nothing else being available 4 Set Default CPM Security of Process Figure 18 Default CPT Dialog for Attributes Relation 2 5 2 1 Setting of discrete aggregation functions Discrete attributes can be aggregated through Max Min or Average CPTs The function of them is described in MEKs and PJs book The states of the default CPT
9. ance that models and decisions are not based on flawed or biased data By requiring the user to specify the credibility of the data used the EA T tool manages this aspect of data collection Enterprise architecture The discipline of advocates the use of models to support decision making on enterprise wide information system issues By analyzing the relevant data in a structured and preferably quantitative way better management decisions can be made Entity An entity is a modeling concept usually referring to something that is an object in the real world Enterprise CRM system computer and project team are all examples of possible entities Entities have attributes and belong to classes Evidence Evidence is the data about real world circumstances collected for the purpose of enterprise architecture analysis Such evidence is never certain but rather has a level of credibility that can be taken into account when performing the analysis The EA T concrete modeler allows the user to provide evidence s regarding the states of every attribute including the more complex ones should such knowledge be available Model A model is a simplified representation of the real world specifically designed to capture the aspects relevant for a certain purpose and leave other aspects out Enterprise architecture models try to incorporate those features relevant to decision making on enterprise wide information system issues The EA T tool distingu
10. asible or not As mentioned in the first step assessment scoping the decision maker identifies the available decision alternatives i e the enterprise information system scenarios In this step the decision maker also needs to determine how the scenario should be evaluated i e the goal of the assessment One such goal could be to assess the security of an information system Other goals could be to assess the availability interoperability or data quality of the proposed to be architecture Often several quality attributes are desirable goals In this paper without loss of generality we simplify the problem to the assessment of security of an electric power station Information about the involved systems and their organizational context is required for a good understanding of their data quality For instance it is reasonable to believe that a firewall would increase the probability that the system is secure The availability of the firewall is thus one factor that can affect the security and should therefore be recorded in the scenario model The decision maker needs to understand what information to gather and also ensure that this information is indeed collected and modeled Overall the effort aims to understand which attributes causally influence the selected goal viz data quality It might happen that the attributes identified do not directly influence the goal If so an iterative approach can be employed to identify further attributes causa
11. attributes are allowed to get linked to discrete ones Attribute Relations need to be based on Slots where an internal Attribute relationship is an exception see below Therefore at first slots need to be present before Attributes can be related This can also be done iterative When slots are present two attributes can be related by holding the ctrl key and drawing a connection from the first to the second one Once this is done a dialog is shown that allows selecting the slots that the attribute relationship is based on Set Slot Chain Process TimeRequired gt System Capacity Source dass Process Internal Reference step 1 ss System Ref 1 Figure 17 Path Determination Dialog for Attributes Relation Sequentially from source to target slots can be selected that are used as basis to this Attribute relationship When the target is reached green icons symbolize that the relation is valid Yellow arrows allow going one step back when a correction of the path is needed Attributes need to be related in order to serve as input to each other This means that in case that discrete Attributes are used the states of the Attributes only appear when the Attributes have been related previously For continuous variables it means that before Attributes can be used in equations they need to be related 2 5 1 Adding of internal Attribute Relationships Attributes of the same class might also be related without the usage of
12. ble even in complex models A description might be add from the context menu too System yst Add Attribute Securit h Set Superclass Response T Self References F Edit References m Set Description Shape d Delete Class Figure 6 Context menu for a Class Set Super Class option will lead to following dialog Set Superclass Setting supercass for System Any currently set attributes with same names as those of superdass will be replaced by the ones from the superclass Proceed with caution e ES Figure 7 Set Super Class Dialog 2 3 Adding Slots Classes can be related to each other via slots This is done by holding the ctri key and drawing a relation from one Class to another one Afterwards those slots can be configured from their context menu available through a right click ome Process System Refi urity Set Properties Security Show Routing Response Time Delete Reference Slot Figure 8 Context menu for Slot Reference Three options are possible at first the properties of the slots can be set second the routing can be adjusted and third they can be deleted The properties that can be adjusted are multiplicities role names and the name of the slots in general If the routing is activated than a double click on a slot allows to either set or remove a control point which is a fixed point that is part of a slot Set Reference Slot Properties Figure 9 Slot Refe
13. distribution depending on the result The distributions are presented in terms of e Mean value e Variance e Skewness e Kurtosis e Samples e Histogram with individual amount of bins Figure 14 Single Value Values for CE Variance SkEWNESS Kurtosis 219 934525 0 071474 0 209863 Bins Histogram E E ss o a za a ec a i i i i i Occurances Figure 15 Probability Distribution 3 6 Replacement of used theory As mentioned previously the tool supports the replacement and update of the used theory The tool tries to match and perform updates as far as possible completely autonomously In case of ambiguities the tool questions the user to solve them l Discrepancies in Prm Figure 16 Ambiguities in Theory Replacement It is possible to change evidence in case the attributes have been changed E l Discrepancies in Prm Discrepancies found between current IPrm and Prm High H of Entity Unnamed 2 Security Figure 17 Change Evidence CPT At the end of a theory replacement a dialog presents the modifications that have been made 4 Quick reference Abstract modeler The abstract modeler is the part of the EA T where the underlying theory for enterprise architecture assessments is specified Here the concepts and relationships relevant for different kinds of analysis is defined thus enabling the users of the concrete modeler to perform advanced assessments in an
14. ers to Export to XML on the one hand and to Import From XML on the other hand Executing the export function creates an xml document that reflects the content of the model whereas the import allows reading a model from an xml file which has been created earlier Additionally the program can be closed from the file menu i Abstract Modeller 0 Help Export To AML Import From AML Exit Ctrl Q Figure 2 The File menu of Abstract Modeler 2 1 3 Tool bar The toolbar as displayed below allows for easy access to the most common functions of the tool O BEE BP add class aj Figure 3 The toolbar of the EAT concrete modeller containing the most common commands Starting from the left there at first the possibility to clear the scene and thereby to start with a new model can be found The second function allows opening of an existing model This is followed by both save and Save as functionality A button to add classes is offered next and finally screenshots of the model can be made 2 1 4 Info palette Information on the current model is presented in this information area System Description Reference Slots Process Ref 1 Process Ref2 Attributes Security ResponseTime Capacity Figure 4 The Info Palette It shows the information about selected object At the top of the info palette a satellite view can be found This presents an overview of the model and is meant to help orienting and navigating wi
15. ew IPrm Class 2s Instantiate Classes Figure 5 Multi Instantiation Dialog Screenshots of the model can be made as well Finally the Calculate button allows evaluating a model 3 1 4 Info palette Information on the current model is presented in this information area Sorat Pier pests x aor Ler _ a POE F aor Ler Pa eT Le Tages J e gt reo CeoFcic Figure 6 Satellite View At the top of the info palette a satellite view can be found This presents an overview of the model and is meant to help orienting and navigating within large models Below information panel can be found Here a short Summary of the selected model element is presented Server Description Process X pe Process Ref 1 pu Security Reference Slots Security P 7 Process X Refi ResponseTime Attributes Timekll aps ed Capacity Security Response Time Capaaty Figure 7 Info Palette showing information of Server System The third panel allows to instantiate the classes contained in the used theory The amounts of instantiations at a time can be set via spinners manual prm Process l System l Figure 8 Instantiation Panel In the lowest part of the info palette several filters can be switched on or off They are e To show the connections on top of the entities e To show the relations between attributes e To show the relations between classes e To show the labels of the rela
16. g relatiONnSHipS ccccccesseeeseeeeeeeeeeeeeeeaueuaeaeas 3 4 Addin eviden CE ennie A AO i 3 4 1 Adding evidence for discrete Attributes sessssersrse ZA L e GredibItY MatriX wunaiacreinecdetetewetmincet tosieaermsenselt 3 4 2 Adding evidence for 3 5 Calculating the model 3 6 Replacement of used theory 4 Quick reference continuous Attributes ccc cececeecaueeceueas 30 EA T User manual This document is a user manual for the Enterprise architecture Assessment EA T tool For more information about the tool project confer http www ics kth se eat 1 Background The discipline of enterprise architecture advocates the use of models to Support decision making on enterprise wide information system issues In order to provide such support enterprise architecture models should be amenable to analyses of various properties as e g the availability performance interoperability modifiability and information security of the modeled enterprise information systems This manual describes a software tool for such analyses EA T is an acronym for Enterprise Architecture Analysis Tool and is a software system for modeling and analysis of enterprises and their information systems The EA T tool supports analysis of enterprise architecture models The tool guides the creation of enterprise information system scenarios in the form of enterprise architecture models and generates quantitative assessments of
17. ishes two types of models the abstract model that speak of general relationships between entities such as availability and maintenance organizations and concrete models that speak of particular companies and situations such as the availability of system X on company Y The idea is that the abstract models are provided by researchers as support for the industry that deals primarily with concrete models Object See Entity Relationship Relationships describe how different classes relate to each other Observable regularities in the real world are modeled as relationships such as when the reliability of components decreases the maintenance costs increase Relationships based on research are created in the abstract modeler where they serve as templates for analyses in the concrete modeler
18. licking the attribute and selecting Evidence Figure 12 illustrates the display that appears Indata 2 Edicence Figure 12 The evidence dialog For Continuous Attribute This attribute can be described in terms of either a fixed 3 5 Calculating the model Once the model is complete in terms of objects relationships and evidence on the attributes it is possible to perform the actual assessment Since each concrete model has an underlying abstract model that defines the theory the user only have to request that the analysis is to take place The theory is then applied to the model using and all the attributes are evaluated The Model is calculated by pressing the calculate button in the tool bar To display the result of the assessment right click on the attribute of interest the Show values option The results of the assessment are displayed according to the type of attribute that is considered Discrete attributes are presented as probability distributions In the example given in Figure10 below it is possible to see that the degree of preparedness for occurrence of incidents is assessed to being high with a 65 probability medium with a 25 probability and low with 10 probability Figure 13 The result of an assessment showing a probability distribution for the attribute Degree of preparedness for occurrence of incidents Continuous variables are either presented as single value or as probability
19. lity distribution over an architecture model The template describes the meta model for the architecture model and the probabilistic dependencies between attributes of the architecture objects A PRM together with an instantiated architecture model of specific objects and relations defines a probability distribution overv the attributes of the objects The probability distribution can be used to infer the values of unknown attributes given evidence of the values of a set of known attributes PRMs are related to Bayesian Networks PRMs are to Bayesian networks as relational logic is to propositional logic 1 2 The theory behind the tool Enterprise architecture models serve several purposes Kurpjuweit and Winter identify three distinct modeling purposes with regard to information systems viz i documentation and communication ii analysis and explanation and iii design The present article focuses on the analysis and explanation which is not to denigrate the usefulness of the others The reason is that analysis and explanation are closely related to the notion of proper goals for enterprise architecture efforts For example a business goal of decreasing downtime costs immediately leads to an analysis interest in availability This in turn defines the modeling needs e g the need to collect data on mean times to failure and repair In this sense analysis is at the core of making rational decisions about information systems An anal
20. lly affecting the attributes found in the previous iteration This iterative process continues until all paths of attributes and causal relations between them have been broken down into attributes that are directly controllable for the decision maker cf Fig 2 Goal decomposition Goal decomposition iteration result Goal selection Indirectly controllable Directly controllable Figur 2 Goal decomposition method In the second step collecting evidence the scenarios need to be detailed with actual information to facilitate their analysis of them Thus once the appropriate attributes have been set the corresponding data is collected throughout the organization In particular it should be noted here that the collected data will not be perfect Rather it risks being incomplete and uncertain The tool handles this by allowing the user to enter the credibility of the evidence depending on how large the deviations from the true value are judged to be In the third and final step performing the analysis the decision alternatives are analyzed with respect to the goal set e g security The mathematical formalism plays a vital role in this analysis Using conditional probabilities and Bayes rule it is possible to infer the values of the variables in the goal decomposition under different architecture scenarios By using the PRM formalism the architecture analysis accounts for two kinds of potential uncertainties that of the
21. match the states of the attribute they are supposed to replace System Process Security pi Ho E Security View Slot Chain 2 d Response Jime Aggregation Function MIN Set Default MAX Capacity v AVG Show Routing X Delete Attribute Kinship Figure 19 Aggregation Functions for Attributes Relation 2 5 2 2 Setting of continuous aggregation functions Continuous attributes can be aggregated through summation product or calculation of average System G Process Security prea Y n Security ResponseTime mekllapsed Capacity s View Slot Chain Aggregation Function SUM Set Default PRODUCT AVG Show Routing A X Delete Attribute Kinship Figure 20 Aggregation function for continuous attributes A default equation can be set as well The dialog is similar to the one for setting Attribute properties the only difference is that no variables in terms of other Attributes can be used CO Figure 21 Default Equation for continuous Attribute 3 Modeling in EA T Concrete Modeler The theory specified in the Abstract modeler can be applied in the concrete part of the tool 3 1 Starting EA T The EA T concrete modeler is written in Java to enable platform independence and thus requires Java JRE to run if missing it can be downloaded at http www java com For windows users the program is started by running from the command line using the command java jar ConcreteModellerIPrm alte
22. rence Properties It is also possible to add a slot from a certain Class to the same again This is done via the Self References menu of the Class context menu oo Process System Ret 1 Add Attribute ee ity Securii hy Set Superclass Response Self References A Add Undirected Edit References C3 Add Directed Edit ql Set Description Shape Delete Class Figure 10 Self Reference menu Either undirected or directed self references can be used System os Process Refi Security oo Seonraty Response Time Figure 11 Undirected Self Reference The difference is that undirected self references can be used to relate attributes of an object of Class A to a second one and the other way around whereas directed one only allow relations from one object to another one Slots determine which and how many relations are possible in the instantiations see below Create Directed Self Reference Set Properties As this is a directed self reference at least one label must be set Figure 12 Directed Self Reference and Properties of Self Reference System G Process Security re a z t enia ecurity ResponseTime TLimekliapsed Capacity Figure 13 Directed Self Reference will be shown by directed self reference icon on top of class 2 4 Adding Attributes Attributes are used to describe Classes They can be added from the context menu of a certain clas
23. rnatively a double click on ConcreteModellerIPrm jar starts the tool too 3 1 1 Getting familiar with the user interface When starting the concrete modeler the following dialog is displayed Load Abstract Model File Welcome As you are starting the Enterprise Architecture Tool for the first time you need to specify which abstract model to use as meta model or which concrete model to use Please select the abstract model file prm or concrete model file iPrm to use File Cancel Figure 1 Start Up Dialog Here the user might load a previously done model and continue his work on that or he can start with an empty model As an empty model needs to be based upon a predefined theory this needs to be loaded in order to start otherwise Afterwards the following window is displayed ff Concrete Modeller File Help O BoE Add class ag manual prm T Ts Attributes Relation Class Relations Show Reference Labels Show Attributes GuidLines With Move T Figure 2 The main window of the EAT concrete modeler with modeling pane menu bar tool bar and status bar This view is dominated by the large modeling area the white part of the window Apart from this there is the menu bar and the tool bar at the top of the screen and the info palette on the right Following is a short description of the menu choices and buttons in the tool bar as well as the info palette 3 1 2 Menu bar The
24. s Several types of Attributes are supported which are explained in detail below Add Attribute 4b Add Discrete Attribute Security ce Add Continuous Attribute System o Process hi Set Superclass Self References F Edit References Set Description Shape w Delete Class Figure 14 Adding New Attribute A description can be added to all Attributes this function is executed from the attribute s context menu 2 4 1 Adding Discrete Attributes Discrete Attributes allow the description of classes in terms of states On default the used states are high medium and low But this can be changed through the Set Attribute Properties function It is also possible to use 1 2 3 4 and 5 or true and false Additionally even customized states are possible This can be figured in the upper part of the Set CPM dialog Set CPM seanty n u T E EE Mo pasha p3 E E EE Figure 15 Setting CPM for Discrete Attribute In case of customized states the plus button allows the adding of additional states The probabilities that the considered variable is in a certain state on a scale from O to 1 based on its potential parents can be set in this dialog 2 4 2 Adding Continuous Attributes Continuous Attributes allow the description of classes in terms of mathematical equations which even can be probability distribution functions The Set Attribute Properties function opens a dialog that allows these
25. the scenarios as they evolve Assessments can be of various quality attributes such as information security interoperability maintainability performance availability usability functional suitability and accuracy The EAT tool consists of two parts the abstract modeler for defining the underlying theory for the assessment and the concrete modeler for modeling enterprises and performing assessments Theory definition is the activity of identifying which phenomena are relevant for achieving the system properties For instance security analysis requires modeling of entities such as firewalls intrusion detection systems anti malware functions access right definition and implementation training of personnel the existence of business continuity plans and much more In the abstract modeler the structure and importance of these phenomena is modeled The abstract modeler is thus mainly aimed to be used by researchers The second part of the tool is the concrete modeler which is used to model concrete instances of system scenarios The concrete modeler uses the theoretical framework developed in the abstract modeler The concrete modeler is mainly intended to be used by the industry While this manual focuses on the concrete modeler information about the abstract modeler can be obtained from the project team at EAT ics kth se 1 1 Probabilistic relational models PRMs A probabilistic relational model PRM specifies a template for a probabi
26. thin large models Below an information panel can be found Here a short summary of the selected model element is presented In the lowest part of the info palette several filters can be switched on or off They are e To show the connections on top of the entities e To show the relations between attributes e To show the relations between classes e To show the labels of the relationships e To show attributes e To show reference lines a Attribute Relations Y Class Relations 7 Show Labels iy Attributes J Guides with move Figure 5 The Filter Panel 2 2 Adding Classes Classes can be added either from the already described button in the tool bar or from the context menu available through a right click Classes describe the central parts of the model They can be derived from real objects such as person or system Also a more abstract level of entities is possible such as function or process which have no physical real world counterpart They are depicted like classes in a class diagram as a rectangle with the name of the class at the top of the box and a line separating it from the rest of the box Classes can inherit properties from already existing classes which can be selected from their context menu therefore the option Set Superclass needs to be used Classes can be attributed see description below It is also possible to bring to front them so that they get visi
27. tionships e To show attributes e To show reference lines J a Attributes Relation Class Relations 7 Uj Show Reference Labels Show Attributes 7 GuidLines With Move Figure 9 Filter Panel 3 2 Instantiating Classes Classes are instantiated from the tool bar as described above or by selecting the amount of Objects in the info palette Instantiating a Class means that the created Object has attributes associated with that type in the abstract model For instance the class system might contain attributes such as information security or performance whereas for the class process attributes such as efficiency or cycle time could be appropriate The exact attributes of the classes as well as what classes that are available is specified by the abstract model the theory developed in the EA T Abstract Modeler 3 3 Instantiating relationships Relationships are created between two classes and specify which relation those classes have Which relationships are valid is defined in the underlying abstract model To create a relationship press and hold the Ctrl key while dragging between the classes The order of source and target is not In this dialog it is possible to choose which relationship to create using the drop down list since there might be more than one option that is valid according to the abstract model Select Reference Slot gt Ref 1 Process X Process X Figure 10 Relation
28. ton If its 100 assure that an Attribute is in a certain state this can also be expressed by fixing that Attribute to always assume that state The context menu of that Attribute offers therefore the function Set State Out of all the possible states that the Attribute might be in the right one can be chosen 3 4 1 1 Credibility Matrix The credibility matrix makes it possible to express the credibility of a source of evidence The matrix represents the probability that the attribute is in each of its states given the evidence More formally the matrix specifies P A E where A is the attribute and E is the evidence In the current version of the tool this matrix is predefined to the one shown in Figure which should be interpreted as follows Given an evidence that the attribute is in state high there is a 95 probability that the attribute actually is in the state high and a 2 5 probability that the attribute is in state medium or low respectively Similarly given evidences on states medium or low there is a 95 probability that the attribute is in the same state as the evidence and a 2 5 probability that it is in any of the other states Future versions of the tool will allow the modeler to define this matrix according to the type of evidence used Some information sources are simply more credible than others 3 4 2 Adding evidence for continuous Attributes Evidence regarding the state of a concrete attribute is given by right c
29. ysis centric process of enterprise architecture is illustrated in Fig 1 In the first step assessment scoping the problem is described in terms of one or a set of potential future scenarios of the enterprise and in terms of the assessment criteria with its theory the PRM in the figure to be used for scenario evaluation In the second step the scenarios are detailed by a process of evidence collection resulting in a model instantiated PRM in the figure for each scenario In the final step analysis quantitative values of the models quality attributes are calculated and the results are then visualized in the form of e g enterprise architecture diagrams Assessment Scoping Evidence Collection Analysis Model Builder Calculation Visualization Function Function Function 7 aS Scenarios Figur 1 The process of enterprise architecture analysis with three main activities i setting the goal ii collecting evidence and iii performing the analysis Mi ii Probabilistic Relational Evidence Instantiated PRM More concretely assume that a decision maker in an electric utility is contemplating changes related to the configuration of a substation The modification of a new access control policy would reduce the probability that someone installs malware on a system and thereby reduce the risk that this type of unwanted software is executed The question for the decision maker is whether this change is fe
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