We present ClearView, a system for automatically patching errors in deployed software. ClearView works on stripped Windows x86 binaries without any need for source code, debugging information, or other external information, and without human intervention.ClearView (1) observes normal executions to learn invariants that characterize the application's normal behavior, (2) uses error detectors to monitor the execution to detect failures, (3) identifies violations of learned invariants that occur during failed executions, (4) generates candidate repair patches that enforce selected invariants by changing the state or the flow of control to make the invariant true, and (5) observes the continued execution of patched applications to select the most successful patch.ClearView is designed to correct errors in software with high availability requirements. Aspects of ClearView that make it particularly appropriate for this context include its ability to generate patches without human intervention, to apply and remove patches in running applications without requiring restarts or otherwise perturbing the execution, and to identify and discard ineffective or damaging patches by evaluating the continued behavior of patched applications.In a Red Team exercise, ClearView survived attacks that exploit security vulnerabilities. A hostile external Red Team developed ten code-injection exploits and used these exploits to repeatedly attack an application protected by ClearView. ClearView detected and blocked all of the attacks. For seven of the ten exploits, ClearView automatically generated patches that corrected the error, enabling the application to survive the attacks and successfully process subsequent inputs. The Red Team also attempted to make ClearView apply an undesirable patch, but ClearView's patch evaluation mechanism enabled ClearView to identify and discard both ineffective patches and damaging patches.
Case Study Comparison of Four Maintenance Programs (Piotrowski 2001) Reactive Maintenance (Breakdown or Run-to-Failure Maintenance) O&M Best Practices 7.1 O&M Best Practices 7.35 O&M Best Practices 7.55 O&M Best Practices 7.81Building envelope -The exterior surfaces of a building that are exposed to the weather, i.e., walls, roof, windows, doors, etc.Celsius (Centigrade) -The temperature at which the freezing point of water is 0 degrees and the boiling point is 100 degrees at sea level.Centrifugal fan -A device for propelling air by centrifugal action.cfm -Cubic feet per minute usually refers to the volume of air being moved through an air duct.O&M Best Practices A.1Chiller -A refrigeration machine using mechanical energy input to drive a centrifugal compressor to generate chilled water.Coefficient of performance -Ratio of tons of refrigeration produced to energy required to operate equipment.Coefficient of utilization -Ratio of lumens on the work surface to total lumens emitted by the lamps.Cold deck -A cold air chamber forming a part of an air conditioning system.Combined wastewater -A facility's total wastewater, both graywater and blackwater.Color rendering index (CRI) -The color appearance of an object under a light source as compared to a reference source.Condensate -Water obtained by charging the state of water vapor (i.e., steam or moisture in air) from a gas to a liquid usually by cooling.Condenser -A heat exchanger which removes heat from vapor, changing it to its liquid state. In refrigeration systems, this is the component which rejects heat.Conduction -Method of heat transfer in which heat moves through a solid.Convection -Method of heat transfer in which heat moves by motion of a fluid or gas, usually air.Cooling tower -A device that cools water directly by evaporation.Damper -A device used to limit the volume of air passing through an air outlet, inlet, or duct.Degree days -The degree day for any given day is the difference between 65 degrees and the average daily temperature. For example, if the average temperature is 50 degrees, the degree days is 65 -50 = 15 degrees days. When accumulated for a season, degree days measure the severity of the entire season.Demand load -The maximum continuous requirement for electricity measured during a specified amount of time, usually 15 minutes.Demand factor -The ratio of the maximum demand of a system to the total connected load on the system.Double bundle chiller -A condenser usually in a refrigeration machine that contains two separate tube bundles allowing the option of rejecting heat to the cooling tower or to another building system requiring heat input.Dry bulb temperature -The measure of the sensible temperature of air.Economizer cycle -A method of operating a ventilation system to reduce refrigeration load. Whenever the outside air conditions are more favorable (lower heat content) than return air condi tions, outdoor air quantity is increased.Efficacy -Ratio of usable light to energy input for a lighting fixture or system (lumens per watt)A.2 O&M Bes...
The mission of FEMP is to facilitate the Federal Government's implementation of sound, costeffective energy management and investment practices to enhance the nation's energy security and environmental stewardship. Each of these activities is directly related to achieving requirements set forth in:• The Energy Policy Act of 2005, which established a number of energy and water management goals for Federal facilities and fleets and also amended portions of the National Energy Conservation Policy Act (NECPA).• Executive Order 13423, Strengthening Federal Environmental, Energy, and Transportation Management (signed in January 2007). This set more challenging goals than EPAct 2005 and superseded existing executive orders 13123 and 13149.• The Energy Independence and Security Act of 2007, which further established energy, water, and building commissioning management goals and requirements and also amended portions of EPAct 2005 and NECPA. EISA was signed into law in December 2007. • Executive Order 13514, Federal Leadership in Environmental, Energy and Economic Performance(signed in October of 2009) directs Federal agencies to further address energy, water, and operational efficiency beyond E.O. 13423 with targeted goals and actions.Release 3.0 of this guide provides updates to Release 2.0 in the areas of O&M technologies, equipment performance, and costs. This new release also addresses water use and the impacts that recommended O&M practices can have on water efficiency.Overall, this guide highlights O&M programs targeting energy and water efficiency that are estimated to save 5% to 20% on energy bills without a significant capital investment. Depending on the Federal site, these savings can represent thousands to hundreds-of-thousands dollars each year, and many can be achieved with minimal cash outlays. In addition to energy/resource savings, a well-run O&M program will:• Increase the safety of all staff, as properly maintained equipment is safer equipment.• Ensure the comfort, health, and safety of building occupants through properly functioning equipment providing a healthy indoor environment.• Confirm the design life expectancy of equipment is achieved.• Facilitate the compliance with the above-mentioned Acts and Orders as well as Federal legislation such as the Clean Air Act and the Clean Water Act, as well as expected carbon mitigation legislation.The focus of this guide is to provide the Federal O&M/Energy manager and practitioner with information and actions aimed at achieving these savings and benefits. Beth Shearer, of Beth Shearer and Associates, provided a conscientious review of material provided in this version of the document. She provided invaluable comments and suggestions to improve the quality of the document.Finally, the authors would like to extend their appreciation to PNNL's document production team -Dave Payson and Elaine Schneider -for the conscientious, team-oriented, and high quality assistance they brought to this version of the document. Tools .....................................
For domain specific languages, "scripting languages", dynamic languages, and for virtual machine-based languages, the most straightforward implementation strategy is to write an interpreter. A simple interpreter consists of a loop that fetches the next bytecode, dispatches to the routine handling that bytecode, then loops. There are many ways to improve upon this simple mechanism, but as long as the execution of the program is driven by a representation of the program other than as a stream of native instructions, there will be some "interpretive overhead".There is a long history of approaches to removing interpretive overhead from programming language implementations. In practice, what often happens is that, once an interpreted language becomes popular, pressure builds to improve performance until eventually a project is undertaken to implement a native Just In Time (JIT) compiler for the language. Implementing a JIT is usually a large effort, affects a significant part of the existing language implementation, and adds a significant amount of code and complexity to the overall code base.In this paper, we present an innovative approach that dynamically removes much of the interpreted overhead from language implementations, with minimal instrumentation of the original interpreter. While it does not give the performance improvements of hand-crafted native compilers, our system provides an appealing point on the language implementation spectrum.
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