1
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- Week 12
- LBSC 690
- Information Technology
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2
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- Search component model
- Work a “shuttle launch” example
- Term weighting; TF and DF
- Combining evidence
- Content, metadata, behavior
- Anchor text
- Why it doesn’t work better than it does!
- Precision-Recall curves
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3
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4
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- Questions
- Systems analysis
- Building complex systems
- Managing complex systems
- Final exam review
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5
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- Acquisition strategy
- Off-the-shelf (“COTS”)
- Custom-developed
- Implementation strategy
- “Best-of-breed”
- Integrated system
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6
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- Self-contained (e.g., PDA)
- Requires replication of software and data
- Client-server (e.g., Web)
- Some functions done centrally, others locally
- Peer-to-peer (e.g., Skype)
- All data and computation is distributed
- “Cloud computing”
- Centrally managed data and compute centers
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7
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8
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9
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10
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- Interactive (“timesharing”)
- Usually multiple processes on one machine
- Possibly supporting different users
- Batch processing (e.g., recall notices)
- Save it up and do it all at once
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11
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- Systems analysis
- How do we know what kind of system to build?
- User-centered design
- How do we discern and satisfy user needs?
- Implementation
- Management
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12
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- User-centered
- System-centered
- Availability
- Mean Time Between Failures (MTBF)
- Mean Time To Repair (MTTR)
- Capacity
- Number of users for each application
- Response time
- Flexibility
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13
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- First steps:
- Understand the task
- Limitations of existing approaches
- Understand the environment
- Structure of the industry, feasibility study
- Then identify the information flows
- e.g., Serials use impacts cancellation policy
- Then design a solution
- And test it against the real need
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14
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- Where does information originate?
- Might come from multiple sources
- Feedback loops may have no identifiable source
- Which parts should be automated?
- Some things are easier to do without computers
- Which automated parts should be integrated?
- What existing systems are involved?
- What information do they contain?
- Which systems should be retained?
- What data will require
“retrospective conversion”?
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15
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- Process Modeling
- Structured analysis and design
- Entity-relationship diagrams
- Data-flow diagrams
- Object Modeling
- Object-oriented analysis and design
- Unified Modeling Language (UML)
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16
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- Acquisition
- Cataloging
- Reference
- Online Public Access Catalog (OPAC)
- Circulation
- Weeding
- Reserve, recall, fines, interlibrary loan, …
- Budget, facilities schedules, payroll, ...
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17
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- What functions should be integrated?
- What are the key data flows?
- Which of those should be automated?
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18
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19
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- Requirements analysis
- Specifies what the software is supposed to do
- Specification
- “Specification” defines the design of the software
- Implementation
- Verification
- “Test Plan” defines how you will know that it did it
- Maintenance
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20
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- Build what you think you need
- Perhaps using the waterfall model
- Get a few users to help you debug it
- First an “alpha” release, then a “beta” rel=
ease
- Release it as a product (version 1.0)
- Make small changes as needed (1.1, 1.2, ….)
- Save big changes for a major new release
- Often based on a total redesign (2.0, 3.0, …)
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21
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22
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- The waterfall model doesn’t work well
- Requirements usually incomplete or incorrect
- The spiral model is expensive
- Redesign leads to recoding and retesting
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23
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- Goal: explore requirements
- Without building the complete product
- Start with part of the functionality
- That will (hopefully) yield significant insight
- Build a prototype
- Focus on core functionality, not in efficiency
- Use the prototype to refine the requirements
- Repeat the process, expanding functionality
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24
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25
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- Policy
- Privacy, access control, appropriate use, …
- Training
- System staff, organization staff, “end users”
- Operations
- Fault detection and response
- Backup and disaster recovery
- Audit
- Cost control (system staff, periodic upgrades, …)
- Planning
- Capacity assessment, predictive reliability, …
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26
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- Planning
- Installation
- Facilities, hardware, software, integration, migration, disruption<=
/li>
- Training
- System staff, operations staff, end users
- Operations
- System staff, support contracts, outages, recovery, …
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27
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28
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29
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- Bill Gates on Linux (March, 1999):
- “I don’t really think in the commercial market, we̵=
7;ll
see it in any significant way.”
- Microsoft SEC filing (January, 2004):
- “The popularization of the open source movement continues to =
pose
a significant challenge to the company’s business model”=
;
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30
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- More eyes Þ
fewer bugs
- Iterative releases Þ rapid bug fixes
- Rich community Þ more ideas
- Coders, testers, debuggers, users
- Distributed by developers Þ truth in advertising
- Open data formats Þ Easier integration
- Standardized licenses
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31
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- Communities require incentives
- Much open source development is underwritten
- Developers are calling the shots
- Can result in feature explosion
- Proliferation of “orphans”
- Diffused accountability
- Fragmentation
- “Forking” may lead to competing versions
- Little control over schedule
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32
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- You can control any two of:
- Open source software takes this to an extreme
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33
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- Support Sellers
- Loss Leader
- Widget Frosting
- Accessorizing
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34
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- Check out Risks Digest for a random date
- http://catless.ncl.ac.uk/Risks
- Pick a random date near your birthday
- Find a case of unexpected consequences
- Try to articulate the root cause
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35
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- Critical system availability
- Why can’t we live without these systems?
- Understandability
- Why can’t we predict what systems will do?
- Nature of bugs
- Why can’t we get rid of them?
- Auditability
- How can we learn to do better in the future?
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36
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- Telecommunications
- Banking and finance
- Energy
- Transportation
- Emergency services
- Food and agriculture
- Water
- Public health
- Postal and shipping
- Defense industrial base
- Hazardous materials
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37
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- Response system
- Analysis, warning, response, recovery
- Threat and vulnerability reduction
- Awareness and training program
- Return on investment, best practices
- Securing government systems
- International cooperation
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38
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- Systems analysis
- Required for complex multi-person tasks
- User-centered design
- Multiple stakeholders complicate the process
- Implementation
- Architecture, open standards, …
- Management
- Typically the biggest cost driver
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39
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40
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