1. Architecture Definition & Analysis Survivable Network Analysis SecurityArchitectures Security Architecture and Analysis:Course Roadmap ArchitectureDevelopment Management Session 1(Linger) What: Methods for defining and reasoning about system architectures. Why: The architecture level is cost-effective and intellectually manageable for analysis and design of system security and survivability capabilities.Session 2, 3a (Linger) What: Survivability analysis improves preservation of critical mission capabilities. Why: No amount of security can guarantee that systems will not be compromised; essential services and assets must be maintained. Sessions 4, 6, 7. 9, 11 (Longstaff) What:Analysis of vulnerabilities and methods for improving system security. Why: System security can be improved by a variety of techniques at the network, operating system, and application level.Session 13 (Linger) What: Architecture development with COTS components Why: Most security vulnerabilities are the result of poor system development and acquisition practices.From a security perspective, good practices and management methods arecritically important.

• Plus:

Student team project in survivability analysis (Mead)

Guest lectures on special topics

Student presentations

2.

Security Architecture and Analysis:Session 2a

Topics:

Session 1 Review

Architecture Life Cycle, Work Products, and Processes

3. Session 1 Review 4. REVIEW: Architecture Defined

An information system architecture

is aspecificationfordevelopmentof a system

composed ofhardwareandsoftware componentsandconnectors

whoseexternal behaviorsatisfies theenterprise missionand

business requirements

Enterprise mission and business requirements Systemarchitecture Systemdevelopment Systemoperation Validate Design Validate Design 5. REVIEW: Concepts of System Architectures

Architectures are comprised of components and connectors:

Components(Computation)

• Hardware:

Workstations, servers, mainframes, printers, sensors, actuators,

• Software:

Operating systems, data base systems, middleware,

• • browsers, applications, utilities, firewalls, ...

Connectors(Communication)

• Hardware:

• Communication links: routers, switches, public telephone

• network, leased lines, virtual private networks,

• Software:

• Communication protocols: TCP/IP, SNMP, HTTP, FTP , Linkage

• conventions: procedure calls, remote procedure calls, thread

• initiation, ...

6. REVIEW: Concepts of System Architectures

Architecture properties:

• Functional properties

• • Must satisfy domain-specific functional requirements

• • and specifications

• Non-functional properties (the ilities)

• • Must satisfy performance, availability, reliability, safety, security, survivability, maintainability, usability, manageability, properties

Architecture trade-offs:

• Properties can conflict

• Trade-offs seek optimal combinations of properties

• based on cost/benefit analysis

7. REVIEW: Architectural Styles Example: A Bank ATM System Style: Hierarchical, client server, layered ATM ATM ATM ATM ... ATM ATM ATM ATM ... ATM ATM ATM ATM ... Server Server ... Mainframe Server Users Users Users ... Presentation/User Interface Layer Infrastructure/ Communications LayerDomain/Enterprise Logic/ Data Layer 8. Presentation Business Rules Data Access DBMS Fat Client Two Tiers Desktop: Server(s): Presentation Business Rules Data Access DBMS Plump Client Two Tiers Presentation Thin Client Multi-tier Ultra-Thin Client Multi-tier Browser Business Rules Data Access DBMS Business Rules Data Access DBMS REVIEW: Architectural Styles Gartners Two-Tier and Multi-Tier Enterprise Architectures: 9. REVIEW: Architecture Impact of COTS Products

Long history

• Started with environment support

• • Operating systems, data bases, language processors,

• Moving up the food chain

• Specialized applications, middleware, network services, ...

Most architectures today are assembled from COTS products

• Domain-specific vendors

• Bend business processes to match software capabilities

• Glue code ties incompatible products together

COTS characteristics:

• Ties your system capability and evolution to vendors

• Cost savings possible, but risks must be managed

• Functionality and security are what vendor says they are

• • Actual capabilities may differ

• Source code usually not available

• Knowledge of quality and reliability difficult to acquire

• Acceptance testing and configuration management are critical

10. REVIEW: An Architecture Framework Architecture Best Practices: Enterprise modeling and requirements specification Application analysis and design Data analysis and design System integration Network analysis and design Incremental system development Enabling Technologies: Computing & comm. components Microsoft technologies JAVA technologies Web technologies XML technologies Security technologies Architecture patterns Development methods and tools Domain Architectures: EAI architectures E-commerce architectures Directory architectures System management architectures Middleware architectures Industry standard architectures Client Environment: Client relations, people, and culture Enterprise architectures, business models, workflows, & legacy systems Functional, non-functional, & usagerequirements and constraints Processes for Developing Tools for Developing Framework for Developing Goals for Developing Architecture Fundamentals: Architecture role and life cycle Architecture representation and reasoning Architecture processes and work products Architecture analysis and design Architecture modeling and validationArchitecture patterns and properties COTS evaluation and integrationAbility to Develop Marketplace Environment: Partners and alliancesCOTS and component products Service and consultation offerings User groups and standards Parts for Developing System Environment:enterprise architecture, business models, system usage and evolution External Behavior View(System Specification): User tasks and workflows Function and information Stimulus/response behavior Data and Software View(Logical Infrastructure): Middleware and applications Databases and storage systemsOperating systemsHardware and Network View(Physical Infrastructure): Computing hardware: servers, mainframes, PCs,mass storage, Networks, wired & wireless: media, devices, topology, protocolsSystem Requirements:function, and properties of reliability, performance, scalability, security, usability, cost, SYSTEM ARCHITECTURE 11. REVIEW: Box Structure Reasoning for Components

Box Structures

• A systematic model for component analysis and design

• Five fundamental component characteristics: BURST

• • Boundary: What is inside and what is outside?

• • Users: Who are the users?

• • Responses: What is the set of possible responses?

• • Stimuli: What is the set of possible stimuli?

• • Transactions: What are the possible mappings from stimuli toresponses?

• Three fundamental component representations:

• • Black box: Component behavior based on history of use

• • State Box: Component behavior based on retained data

• • Clear box: Component behavior based on procedure (anothercourse!)

12.

The example ofblack box behavior: A hand calculator

REVIEW: Box Structure Reasoning for Components: Black Boxes

The black box of a component in diagram form

Stimulus (S) Response (R) Stimulus Stimulus history Response 716 5 7165 716C 5 5

Black box behavior depends on more than the current stimulus,

it also depends on thehistory of use

Transition functionof a black box description

(stimulus history, stimulus)(response)

13.

Opens up a black box to reveal retained data; allows reasoning about

the state

Transition functionof a state box description

• (stimulus, current state) --> (response, new state)

REVIEW: Box Structure Reasoning for Components: State Boxes

The state box of a component in diagram form

Stimulus (S) Response (R) state trans 14. REVIEW: Compositional Reasoning for Networks A Bank ATM System ATM ATM ATM ATM ... ATM ATM ATM ATM ... ATM ATM ATM ATM ... Server Server ... Mainframe Server Users Users ... Presentation/User Interface Layer Infrastructure/ Communications LayerDomain/Enterprise Logic/ Data Layer 15. REVIEW: Compositional Reasoning for Networks

What happens from viewpoint of ATM user submitting a transaction?

ATM Server Mainframe Server ATM

• [User] o [ATM] o [server] o [mainframe] o [server] o [ATM] o [User]

• • o is composition operator

• • [, ] denote the transition function of the component

• • Note that eachuse of a componentis in the composition

Component compositions are also known asarchitecture traces

ATM Security: Composition with wrong pin number (U for user)

ATM Server ATM Server ATM Server ATM Try again wrong pin Try again wrong pin Access denied User User U U U U U U U U 16. REVIEW: Compositional Reasoning for Networks

Another pin number composition

ATM Server ATM Server ATM Server ATM wrong pin Try again wrong pin Try again right pin Access denied Server ATM Access granted wrong pin

Compositional reasoning is concerned with thenet effectof

all the components in a composition

Net effect means the overall change

• From the stimuli to the first component

• To the response from the last component

U U U U U U U U U U U 17. REVIEW: Compositional Reasoning for Networks When you buy gas at a pump with a speedpass, what is a possible architecture trace of your transaction? ? pump pump User User Despite the fact that thousands of users may be accessing the system at the same time, the system is designed to maintain the compositional integrity of the architecture traces of all the users. It appears to you as though you are the only user. 18. REVIEW: Compositional Reasoning for Networks

Many systems are designed to preserve composition and isolate

asynchronous behavior

Bank system preserves independence of transactions based on

account numbers

In general, systems are designed for compositional operations

A Bank ATM System ATM ATM ATM ATM ... ATM ATM ATM ATM ... ATM ATM ATM ATM ... Server Server ... Mainframe Server Users Users ... 19. Architecture Life Cycle, Work Products,and Processes 20. Architecture FundamentalsArchitecture Practices Client Environment:enterprise arch. legacy systems initial requirements Marketplace Environment Domain Architectures Enabling Technologies INPUTS Architecture Life Cycle: Inputs 21.

If it exists and is current

• May define business models

• May define IT infrastructure

• May define evolutionary objectives

• May provide guidance for architecture development

If it exists and is not current

• Opportunity to update

• Guidance is suspect

Perspective Know the status of enterprise architecture definition Analyze existing enterprise architecture IT infrastructure Evaluate requirements wrt existing infrastructure Architecture Life Cycle: Inputs: Enterprise Architecture Defn 22.

Legacy reuse and integration

• Data, software, and networks involved

• Potential major costs or savings

• Impacts architecture, development, & deployment

Many alternatives possible

• Wrapping, rewriting, transforming, rehosting,

Decision making

• Legacy systems are often difficult to modernize

• Assessment of legacy capabilities is crucial

• Business valuation of legacy assets

• is crucial

• New uses for old data

• Business case, cost/benefit analysis

Perspective Analyze legacy capabilities wrt client requirements Understand evolution plans for legacy assets Treat legacy integration on a par with new components Architect forfirm future usesof legacy elementsArchitecture Life Cycle: Inputs: Legacy systems 23.

Often not fully known by client

• Effective requirements discovery is essential

• Enterprise and business models are the basis

Functionalrequirements

• User tasks and workflows

• System services and transactions

• Use cases are a popular method

Usagerequirements

• User types and roles

• Usage patterns and traffic levels

Non-functional(property) requirements

• Reliability, performance, scalability,

• security, survivability, usability, cost,

Perspective Never architect against presumed requirementsAvoid late-life-cycle requirements surprises Iterate requirements definition with clients Involve all client roles andstakeholders Treat requirements as an architecture entry condition Develop prototypes to elicit requirements from clients Establishrequirements baselinesto manage change andprevent scope creep Architecture Life Cycle: Inputs: Initial Requirements 24.

Partners and alliances

• Partnering can reduce costs and spread risk

COTS products

• Extensive, comprehensive capabilities available

• Vendor capability and track record can be issues

• Product function and quality can beissues

• Trend to standard, integrated solutions

User groups and standards

• Provide experience benchmark,

• enable interoperability

Perspective Capitalize on alliance strategies and agreements Perform due diligence assessments of vendors Evaluate function and quality of COTS products Reconcile COTS capabilities with client requirements Recognize COTS selections tie clients to supply chains Capitalize on accepted standards, avoid othersArchitecture Life Cycle: Inputs: Marketplace Environment 25.

EAI architectures

• Data-, application-, portal-, process-oriented,

• XML, middleware, RPCs, message brokers,

• Packages: SAP, PeopleSoft, BizTalk,

E-commerce architectures

• B2C, B2B, B2G, G2C

• Content, payments, orders, fulfillment,

• Security, trust, privacy, QoS

• Packages, ISPs,

Industry standard architectures

Perspective Capitalize on applicable domain architectures Maintain knowledge ofevolving domain methods Architecture Life Cycle: Inputs: Domain Architectures 26.

Computation & communication hardware

• Processing power and bandwidth

• Intel, Cisco,

• Hardware in continual evolution

Integration environments

• Applications, middleware, operating systems,

• Microsoft, Sun, Oracle,

• Environments in continual evolution

Integration enablers

• HTML, XML, security,

• Enablers in continual evolution

Perspective Maintain knowledge ofevolving technologies Where possible, build on existing client environments Recognize enabler selections tie clients to supply chainsArchitect for component and environment evolution Architecture Life Cycle: Inputs: Enabling Technologies 27. Architecture FundamentalsArchitecture Practices Client Environment:enterprise arch. legacy systems initial requirements Marketplace Environment Domain Architectures Enabling Technologies Final RequirementsPrototypes & Models Architecture Design Architecture ProvisioningArchitecture Validation VendorAgreementsDevelopment Plan INPUTS WORK PRODUCTS Architecture Life Cycle: Work Products 28.

Discovery and reconciliation

• Requirements analysis with client

• User experience with prototypes

• User needs vs. product capabilities

Requirements trade-offs

• Optimal non-functional property mix

• Functional trade-offs:

Goal is no project impact

• Customer understands trade-offs

• Customer agrees to requirements baseline

• Schedule and budget remain intact

Perspective Challenge and confirm key requirements Find any under-represented stakeholders Review property trade-offs with client The baseline plus controlled changes are the final reqs. It doesnt matter how well the wrong system is built Cost Benefit High High Low Low No Go Discuss Go Discuss Architecture Life Cycle: Work Products: Final Requirements 29.

Prototype goals

• Requirements elicitation and finalization

• Proof of concept

Model goals

• Simulation, prediction of system performance

• Proof of concept

Prototyping and Modeling

• Key risk management strategies

• Can be a phase in multi-phase project

Perspective Target prototypes to specific questions and objectives Evolving prototypes into products can be very risky Model results are only as good as model fidelity Model results are only as good as model inputsMatch modeling effort to project stakes Architecture Life Cycle: Work Products: Prototypes & Models 30.

Architecture is the integrating foundation of the project

• A complete abstraction of the final system

• Defers details without losing them

• Development and usage become envisionable

• Basis for reasoning, discussions, and decisions

Satisfies client needs

• Functional and non-functional requirements

• Traceability of requirements into architecture is important

Prescribes system development

• Architecture should leave nothing out at

• its level of abstraction

• Development should refine, not

• invent, architecture

Perspective Get all the guidance, advice, and review you can find Simple and straightforward solutions are best Use what is known to work -- capitalize on similar projects Architecture Life Cycle: Work Products: Architecture Design I 31.

Architecture defines

• External behavior design (system specification)

• • User tasks and workflows

• • Stimulus/response behavior

• Data and software design (logical infrastructure)

• • Retained state, application software,

• • Middleware, operating systems, databases,

• • Partitioning of function and data in an architectural style

• Hardware and network design (physical infrastructure)

• • Servers, mainframes, PCs,

• • Media, devices, topology, protocols,

• Non-functional properties

• • Property definitions

• • How properties are satisfied

• User skills and training

Architecture Life Cycle: Work Products: Architecture Design II 32.

Provide specifications for every component

• Function

• Usage

• Non-functional properties

Provide source for every component

• As-is or modified legacy or COTS

• As-is or modified partner product

• Enabling environment or technology

• New development

• ISP, ASP,

• Various combinations

Perspective Select sources based on component specificationsSatisfy cost objectives Define level of effort for component provisioning Carefully weigh benefits of buy vs. build Develop components as a last resort Architecture Life Cycle: Work Products: Provisioning 33.

Validate architecture functionality

• Every required user function must be present

• All functions must operate harmoniously

Validate non-functional properties

• Every required property must be satisfied

• All properties must co-exist harmoniously

Validation processes

• Verify as-designed against as-specified

• Many methods may be employed

• Team inspections are a key technique

Perspective Treat validation as a distinct task Apply validation entry and exit conditions Ensure artifacts are in shape for validation Validate conformance of artifacts to specifications Document evidence for conformance Iterate validation and rework until artifacts pass Use validation defect rates to manage quality Architecture Life Cycle: Work Products: Validation 34.

Architecture is a driver of vendor agreements

• Incorporates vendor components

• Basis for development plan

• Defines component deliverables

• • Provisioning strategies

• • Requirements and specifications

• Defines service deliverables

• • Scope and QoS

• • Staffing and skills

Perspective Define deliverables for vendor agreements Perform due diligence on vendor capabilities Define checkpoints for assessing vendor progress Define testable acceptance criteria for deliverables Define implications of acceptance failure Manage risk with plan B for critical components Architecture Life Cycle: Work Products: Vendor Agreements 35.

Defines development environment

• Enabling technologies

• Development and testing processes

Defines development steps

• Incremental development is essential

• Stepwise completion of system parts

• Client feedback from early increments

• Tasks and schedules

Perspective Define environment early to drive staffing and training Define steps so that systemaccumulates into final form Be prepared for development feedback to architectureEvaluate early increments wrt required propertiesArchitecture Life Cycle: Work Products: Development Plan 36. Architecture FundamentalsArchitecture Practices Client Environment:enterprise arch. legacy systems initial requirements Marketplace Environment Domain Architectures Enabling Technologies Final RequirementsPrototypes & Models Architecture Design Architecture ProvisioningArchitecture Validation VendorAgreements Development Plan INPUTS WORK PRODUCTS ITERATIVE ARCHITECTURE DEVELOPMENT Ent. Arch., Legacy, Reqs., Market, Domain, Enablers Env. and Steps Analysis Devel. Planning Schedule Mgmt. Plan Planning (Architecture Development) Architecture Life Cycle: Arch. Development 37.

Embedded within project schedule

• Supports project dependencies

Entry conditions (rarely satisfied)

• Stable and complete requirements

• Availability of appropriate staff and resources

Exit condition

• Architecture work products are complete and validated

Perspective Failure to meet schedule is a non-starterSurface schedule-impacting problems early Work at level of abstraction compatible with schedule Architecture Life Cycle: Arch. Development: Schedule 38.

Defines work products

• Project-specific architecture artifacts

Defines tasks

• Activities that will produce the work products

Defines internal schedules and resources

• Task sequencing and resource allocation

Defines risks and mitigations

• Key risks and uncertainties

• Actions for recognition and control

Perspective Plan is a sequencing of tasks plus risk management Define tasks to accumulate into work products Use the plan to manage the architecture work Track actual vs. predicted performance Discovery/experimentation tasks can reduce riskArchitecture Life Cycle: Arch. Development: Management Plan 39.

Understand the client and resources

• Client problem

• • Enterprise architecture and business models

• • Legacy systems

• • Requirements

• • From present operations to envisioned future operations

• Potential resources

• • Marketplace offerings

• • Domain architectures

• • Enabling technologies

A project-long activity

• May require experimentation, training

• Document understandings for decision-making

Perspective Never stop learning about the problem and resources Architecture Life Cycle: Arch. Development: Analysis 40.

Define development environment

Define development and testing steps

Perspective Consult with developers to arrive at a consensus plan Consult with customers on staging of deliverables Architecture Life Cycle: Arch. Development: Development Planning 41. Architecture FundamentalsArchitecture Practices Client Environment:enterprise arch. legacy systems initial requirements Marketplace Environment Domain Architectures Enabling Technologies Final RequirementsPrototypes & Models Architecture Design Architecture ProvisioningArchitecture Validation VendorAgreements Development Plan INPUTS WORK PRODUCTS ITERATIVE ARCHITECTURE DEVELOPMENT External Behavior Data & Software Hardware & Network Design Refine Refine Refine Design Design Ent. Arch., Legacy, Reqs., Market, Domain, Enablers Env. and Steps Validation Checkpoint Analysis Inspection Devel. Planning IterationsSchedule Mgmt. Plan Planning Architecture Life Cycle: Arch. Development: Design Activities 42.

External behavior design maps requirements into specifications

External behavior design plus network traffic, etc., drives data and software design

Data and software design plus network traffic, geography, etc., drives hardware and network design

Non-functional requirements drive everything

System evolution requirements drive everything

Perspective Refinement process allows divide, connect, and conquer strategy Refinement helps maintain intellectual control Refinements can be verified wrt their specifications Cant design the top without knowing the bottom Last intellectual passis top down Architecture Life Cycle: Arch. Development: The Refinement Process 43.

The first idea is rarely the best idea

Iteration drives evaluation and improvement

Iteration permits systematic convergence to a solution

Iteration has desirable properties similar to requirements change control

Iterations document design decisions

Perspective Use iteration to achieve informed agreement Use iteration to uncover gaps and misunderstandings Continually challenge assumptions and decisions Architecture Life Cycle: Arch: Development: The Iteration Process