CSCI 578 Software Architectures Exam 2 Review Materials you are responsible for Chapters 9 17 in the text book Also Chapter 8 on Architectural Analysis since we didn t cover this in the first exam All lecture material from Implementation Architectures through People Roles and Teams Week 15 Homework 3 and Course Project Dan Crichton s lecture Exam Closed book closed note Format Write in answers No multiple choice Material Review Implementing Architectures Mapping problem of design decisions to implementation artifacts code executables etc Common Element Mapping Understand how components connectors interfaces configurations are reified in the actual system implementation One way versus Round trip Mapping Architectural Implementation Frameworks a piece of software that acts as a bridge between a particular architectural style and a set of implementation technologies Material Review Architectural implementation framework examples stdio java io iostream pipe and filter Evaluating architectural implementation frameworks Platform support fidelity matching assumptions efficiency size cost ease of use reliability robustness availability of source code portability long term maintainability and support Middleware Represents the implementation level reification of software connectors New Frameworks Avoid constructing these unless you have to Material Review Implementation Techniques Detailed description of pipe and filter Lunar Lander Material Review Applied Architectures 8 limitations fallacies of distributed computing Deutsch Gosling The network is reliable Latency is zero Bandwidth is infinite The network is secure Topology doesn t change There is one administrator Transport cost is zero The network is homogeneous Material Review Applied Architectures REST WWW Architectural principles Resources resources include metadata bits context free communication stateless small set of well defined methods representation metadata for caching presence of intermediaries to distributed computation workload Akami Caching of content and localized delivery architecture Google MapReduce GFS Distribution of computation parallelization and data over a commodity cluster of machines Material Review Applied Architectures Grid Protocol Architecture Globus P2P Architectures Napster Gnutella Skype Bittorrent Overall takeaways A great architecture is the ticket to runaway success A great architecture reflects deep understanding of the problem domain A great architecture probably combines aspects of several simpler architectures Develop a new architectural style with great care and caution Most likely you don t need a new style Material Review Designing for Non Functional Properties NFPs A software system s non functional property NFP is a constraint on the manner in which the system implements and delivers its functionality Example NFPs Efficiency Complexity Scalability Heterogeneity Adaptability Dependability Material Review Ascertain the role of software architecture in ensuring various NFPs At the level of major architectural building blocks Components Connectors Configurations As embodied in architectural style level design guidelines Efficiency Complexity Scalability Heterogeneity Adaptability Dependability Material Review Security and Trust The protection afforded to an automated information system in order to attain the applicable objectives of preserving the integrity availability and confidentiality of information system resources includes hardware software firmware information data and telecommunications National Institute of Standards and Technology Design Principles Least Privilege give each component only the privileges it requires Fail safe Defaults deny access if explicit permission is absent Economy of Mechanism adopt simple security mechanisms Complete Mediation ensure every access is permitted Design do not rely on secrecy for security Material Review Security and Trust Design Principles Separation of Privilege introduce multiple parties to avoid exploitation of privileges Least Common Mechanism limit critical resource sharing to only a few mechanisms Psychological Acceptability make security mechanisms usable Defense in Depth have multiple layers of countermeasures Material Review Decentralized No centralized authority to coordinate and control entities Independent peers with possibly conflicting goals interact with each other and make local autonomous decisions Presence of malicious peers in open decentralized applications Need for measures to protect peers against malicious attacks Material Review Some Threats of Decentralization Impersonation Mallory says she is Bob to Alice Fraudulent Actions Mallory doesn t complete transactions Misrepresenting Trust Mallory tells everyone Bob is evil Collusion Mallory and Eve tell everyone Bob is evil Addition of Unknowns Alice has never met Bob Decentralized Auctioning Carol Bob Open decentralized application Independent buyers sellers Potentially malicious participants Need to counter Marvin threats malicious Alice Decentralized Auctioning Mallory malicious Impersonation Bob Alice Bob is reliable and everyone has a good opinion about Bob I am Bob Mallory malicious Fraudulent Actions Alice pays for the items Marvin seller malicious Marvin does not ship the items Alice buyer Misrepresentation Bob Alice Bob is reliable and everyone has a good opinion about Bob Bob is unreliable Mallory malicious Bob Collusion Alice Bob is reliable and everyone has a good opinion about Bob Bob is unreliable Marvin malicious Mallory malicious Addition of Unknowns Carol new entrant in the system Bob has no information about Carol he is not sure whether to interact with Carol Bob Carol is new and does not know Alice she is not sure whether to interact with Alice Alice Material Review PACE Architecture HTTP Sender Custom Protocols Multicast Manager Communication Manager Communication Layer Multicast Handler Internal Information Key Manager External Information Credentia l Manager Application Trust Rules APPLI CAT I O N Trust Manager Trust Information Layer Layer Signature Manager Material Review Deployment and Mobility Deployment is the process of placement of a system s software components on its hardware hosts Changing the deployment of a component during runtime is called migration or redeployment Migration or redeployment is a type of software system mobility Mobility entails a superset of deployment issues Material Review 4 Major Deployment Activities Planning Modeling