Quiz#2 . With respect to the RPC mechanism, consider the “exactly once” semantic. Does the algorithm for implementing this semantic execute correctly even if the ACK message back to the client is lost due to a network problem? Describe the sequence of messages and discuss whether “exactly once” is still preserved. Answer: The “exactly once” semantics ensure that a remote procedure will be executed exactly once and only once. The general algorithm for ensuring this combines an acknowledgment (ACK) scheme combined with timestamps (or some other incremental counter that allows the server to distinguish between duplicate messages). The general strategy is for the client to send the RPC to the server along with a timestamp. The client will also start a timeout clock. The client will then wait for one of two occurrences: (1) it will receive an ACK from the server indicating that the remote procedure was performed, or (2) it will time out. If the client times out, it assumes the server was unable to perform the remote procedure so the client invokes the RPC a second time, sending a later timestamp. The client may not receive the ACK for one of two reasons: (1) the original RPC was never received by the server, or (2) the RPC was correctly received—and performed—by the server but the ACK was lost. In situation (1), the use of ACKs allows the server ultimately to receive and …show more content…
Assume that a distributed system is susceptible to server failure. What mechanisms would be required to guarantee the “exactly once” semantics for execution of RPCs? Answer: The server should keep track in stable storage (such as a disk log) information regarding what RPC operations were received, whether they were successfully performed, and the results associated with the operations. When a server crash takes place and a RPC message is received, the server can check whether the RPC had been previously performed and therefore guarantee “exactly once” semantics for the execution of
pecial Conditions Permit Number 9576 1. This permit covers only those sources of emissions listed in the attached table entitled “Emission Sources - Maximum Allowable Emission Rates” (MAERT), and those sources are limited to the emission limits and other conditions specified in that table. Startup, Shutdown, and Maintenance Emissions 2. This permit authorizes emissions from Flare (Emission Point No. [EPN] 400) for startup and shutdown activities associated with product transitions.
BU275 Assignment 2 Equations Question 1 A Station 1: Prep Inter-arrival time is the time between consecutive arrivals of the customers. Because the inter-arrival times are exponentially distributed, customers arrive at random times. The mean is 100 customers/ hours. This indicates that a customer arrives every 0.6 minutes.
1.2 RESEARCH OBJECTIVES: 1.2.1 Creating Data Set The images used in this work have been obtained from the Street View service developed by Google. It provides high- resolution views from various positions along many streets and roads in the world. These images are taken at discrete geographical locations defined by a pair (LAT, LON) (latitude and longitude in decimal degrees, respectively) [19].
I am going to explain the current methods and protocols we use in a LAN environment to provide a high level of redundancy, such as EtherChannel, FHRP (First Hop Redundancy Protocols) and STP (Spanning Tree protocols). I will briefly explain how the protocols work & then discusses the latest implementations of the protocol and the environment you would expect to see them working in. The STP is a protocol that prevents loops from occurring in a switched LAN environments when a device has multiple interconnected paths. The protocols works by sending BDPU messages across in the interconnected devices, detects the loop then removes it from the topology by shutting down the port.
WPA2 –Wi-Fi protected access version 2 This security was made because of the 802.11i wireless security standard. WPA2 is very similar to WPA but it uses AES – advanced encryption standard to encrypt. AES has a 128 bit key whereas DES – data encryption standard which was used before AES has a 64bit key. 64bit keys take a lot less time to break than 128bit key.
6-1. Examples of organizations that could have information silos could be a local restaurant and a chain restaurant. Both probably have information silos if they have a database for each area of work. This could happen if each area doesn 't have a way to communicate their data to the others, which causes problems in the business system running smoothly. For the local store, an EAI would probably be the best because it is for smaller businesses and would disrupt business for a shorter period of time.
\section{Building Blocks} \subsection{Access Structures} \textbf{Definition 3.8.}(Access Structure\citeup{beimel1996secure}) \emph{Let $\{P_1, P_2,...,P_n\}$ be a set of parties. A collection $\mathbb{A}\subseteq 2^{\{P_1,P_2,...,P_n\}}$ is monotone if $B\in\mathbb{A}$ and $B\subseteq C$ implies $C\in\mathbb{A}$. An access structure is a monotone collection $\mathbb{A}$ of non-empty subsets of $\{P_1,P_2,...,P_n\}$, i.e., $\mathbb{A}\subseteq 2^{\{P_1,P_2,...,P_n\}} \setminus\{\emptyset\}$. The sets in $\mathbb{A}$ are called the authorized sets, and the sets not in $\mathbb{A}$ are called the unauthorized sets}. In our settings, attributes will play the role of the parties such that the access structure $\mathbb{A}$ will contain the authorized
Network monitoring now is limited because of the number of servers it takes to deal with the large influx of router data. Router manufacturers have been attempting to combat this by adding counters to the routers that report on the number of data packets a router has processed during some time interval, but adding counters for every special task would be impractical and put more stress on servers since they would need thousands more to process the flood of data coming in. To combat this a system called Marple was created by researchers at MIT, Cisco Systems, and Barefoot Networks(Hardesty). Marple involves a programming language the allows network operators to specify a wide range of network-monitoring tasks and a small set of simple circuit elements that can execute any function specified in the language.
If desired, users will dedicate one method per node to overlap fault tolerance work and scientific computation, so post-checkpoint tasks are dead asynchronously. To be able to absolutely exploit ever larger computing platforms, trendy HPC applications and system computer code should be able to tolerate inevitable faults. traditionally, MPI implementations that incorporated fault tolerance capabilities are restricted by lack of modularity, measurability and value. an application employing a MPI implementation that has fault tolerance services is best equipped to adapt to current and next generation HPC systems. sadly several of those implementations offer sophisticated interfaces to the applying user or need them to make a decision between production
In general, all the predators and prey (regardless of habitat) began with the same amount of population. For instance, there are a total of six predators (2 had forks, 2 had spoons, and 2 had knives)—regardless of habitat, Meaning each predator contributed to 33% of the population (Tables 1A, 2A). For prey, each bean contributed 25% of the population (Tables 1B, 2B). However, as generation progressed, differences began to appear.
The 13 inch MacBook Air MMGF2LL/A is thin, light, and durable enough to take anywhere. With 5th generation Intel processors, fast graphics, and fast PCIe-based flash storage, it’s more than powerful enough for your everyday things like email, web surfing, photo organizing and editing, and more. With all-day battery life, MacBook Air 13 128GB will go with you and stay with you the entire day. The Apple MacBook Air 13 128GB is incredibly thin and light at under an inch and as little as 2.96 pounds.
1. Offer your opinion as to the two critical infrastructure sectors you feel are currently most at risk. Provide reasoning as to why you hold this position and what role the private sector can play in decreasing this risk. In studying critical infrastructure previously, I maintain my belief that the most at risk sector remains food and agriculture.
It has helped to describe the parameters with an emphasis on lifetime of network, reliability, and the dynamic and static of single and multi-hop networks
Do you wish the HP SlateBook 10 x2 had more storage space? If you are willing to root the HP SlateBook device, you can head over to the Google Play Store and install apps such as the Link2SD app. The Link2SD app doesn 't exactly give your device more space. However, it does create an easy way for people to transfer apps over to the SD card to free up more internal memory space. Many people have no idea how to use their SD cards and this Lin2SD app helps those people.
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