Open Systems Interconnection

https://www.edsurge.com/news/2015-12-02-computer-science-goes-beyond-coding

edSurge


OPINION Computer Science Goes Beyond Coding

By Sheena Vaidyanathan Dec 2, 2015

The “teach kids to code” movement has many thinking that computer science is just coding. Often the two are conflated since coding is definitely the most visible component of computer science. It is the magic that turns ideas into products; it provides the motivation to learn computer science. Kids want to learn so they can make cool stuff that is meaningful to them.

However computer science goes beyond just coding. The K-12 standards for computer science, set by the Computer Science Teachers Association, defines the discipline as:

“the study of computers and algorithmic processes, including their principles, their hardware and software designs, their applications, and their impact on society.”

This doodle shows some of these parts of computer science; coding is just one of them.

Computer science is about solving problems using computers and coding (or programming) is about implementing these solutions. Computer scientists can be like architects who design the house—but do not have to build it.

The new high school AP Computer Science principles course more accurately reflects this important distinction by focusing on seven big ideas: Creativity, Abstraction, Data, Algorithms, Programming, Internet, Global Impact. Coding (Programming) is just one of these seven areas.










https://en.wikipedia.org/wiki/OSI_model


OSI model

From Wikipedia, the free encyclopedia

The Open Systems Interconnection model (OSI model) is a conceptual model that characterizes and standardizes the communication functions of a telecommunication or computing system without regard to their underlying internal structure and technology. Its goal is the interoperability of diverse communication systems with standard protocols. The model partitions a communication system into abstraction layers. The original version of the model defined seven layers.

A layer serves the layer above it and is served by the layer below it. For example, a layer that provides error-free communications across a network provides the path needed by applications above it, while it calls the next lower layer to send and receive packets that comprise the contents of that path. Two instances at the same layer are visualized as connected by a horizontal connection in that layer.


Description of OSI layers

The recommendation X.200 describes seven layers, labeled 1 to 7. Layer 1 is the lowest layer in this model.

At each level N, two entities at the communicating devices (layer N peers) exchange protocol data units (PDUs) by means of a layer N protocol. Each PDU contains a payload, called the service data unit (SDU), along with protocol-related headers and/or footers.

Data processing by two communicating OSI-compatible devices is done as such:

The data to be transmitted is composed at the topmost layer of the transmitting device (layer N) into a protocol data unit (PDU).

The PDU is passed to layer N-1, where it is known as the service data unit (SDU).

At layer N-1 the SDU is concatenated with a header, a footer, or both, producing a layer N-1 PDU. It is then passed to layer N-2.

The process continues until reaching the lowermost level, from which the data is transmitted to the receiving device.

At the receiving device the data is passed from the lowest to the highest layer as a series of SDUs while being successively stripped from each layer's header and/or footer, until reaching the topmost layer, where the last of the data is consumed.

Some orthogonal aspects, such as management and security, involve all of the layers (See ITU-T X.800 Recommendation). These services are aimed at improving the CIA triad - confidentiality, integrity, and availability - of the transmitted data. In practice, the availability of a communication service is determined by the interaction between network design and network management protocols. Appropriate choices for both of these are needed to protect against denial of service.[citation needed]

Layer 1: Physical Layer

The physical layer has the following major functions:

It defines the electrical and physical specifications of the data connection. It defines the relationship between a device and a physical transmission medium (e.g., a copper or fiber optical cable, radio frequency). This includes the layout of pins, voltages, line impedance, cable specifications, signal timing and similar characteristics for connected devices and frequency (5 GHz or 2.4 GHz etc) for wireless devices.

It defines transmission mode i.e. simplex, half duplex, full duplex.

It defines the network topology as bus, mesh, or ring being some of the most common.

The physical layer of Parallel SCSI operates in this layer, as do the physical layers of Ethernet and other local-area networks, such as Token Ring, FDDI, ITU-T G.hn, and IEEE 802.11 (Wi-Fi), as well as personal area networks such as Bluetooth and IEEE 802.15.4.

Layer 2: Data Link Layer

The data link layer provides node-to-node data transfer -- a link between two directly connected nodes. It detects and possibly corrects errors that may occur in the physical layer. It, among other things, defines the protocol to establish and terminate a connection between two physically connected devices. It also defines the protocol for flow control between them.

IEEE 802 divides the data link layer into two sublayers:

Media Access Control (MAC) layer - responsible for controlling how devices in a network gain access to data and permission to transmit it.

Logical Link Control (LLC) layer - responsible for identifying Network layer protocols and then encapsulating them and controls error checking and packet synchronization.

The MAC and LLC layers of IEEE 802 networks such as 802.3 Ethernet, 802.11 Wi-Fi, and 802.15.4 ZigBee, operate at the data link layer.

The Point-to-Point Protocol (PPP) is a data link layer that can operate over several different physical layers, such as synchronous and asynchronous serial lines.

The ITU-T G.hn standard, which provides high-speed local area networking over existing wires (power lines, phone lines and coaxial cables), includes a complete data link layer that provides both error correction and flow control by means of a selective-repeat sliding-window protocol.

Layer 3: Network Layer

The network layer provides the functional and procedural means of transferring variable length data sequences (called datagrams) from one node to another connected to the same network. It translates logical network address into physical machine address. A network is a medium to which many nodes can be connected, on which every node has an address and which permits nodes connected to it to transfer messages to other nodes connected to it by merely providing the content of a message and the address of the destination node and letting the network find the way to deliver ("route") the message to the destination node. In addition to message routing, the network may implement message delivery by splitting the message into several fragments, delivering each fragment by a separate route and reassembling the fragments, report delivery errors, etc.

Datagram delivery at the network layer is not guaranteed to be reliable.

A number of layer-management protocols, a function defined in the management annex, ISO 7498/4, belong to the network layer. These include routing protocols, multicast group management, network-layer information and error, and network-layer address assignment. It is the function of the payload that makes these belong to the network layer, not the protocol that carries them.

Layer 4: Transport Layer

The transport layer provides the functional and procedural means of transferring variable-length data sequences from a source to a destination host via one or more networks, while maintaining the quality of service functions.

An example of a transport-layer protocol in the standard Internet stack is Transmission Control Protocol (TCP), usually built on top of the Internet Protocol (IP).

The transport layer controls the reliability of a given link through flow control, segmentation/desegmentation, and error control. Some protocols are state- and connection-oriented. This means that the transport layer can keep track of the segments and retransmit those that fail. The transport layer also provides the acknowledgement of the successful data transmission and sends the next data if no errors occurred. The transport layer creates packets out of the message received from the application layer. Packetizing is a process of dividing the long message into smaller messages.

OSI defines five classes of connection-mode transport protocols ranging from class 0 (which is also known as TP0 and provides the fewest features) to class 4 (TP4, designed for less reliable networks, similar to the Internet). Class 0 contains no error recovery, and was designed for use on network layers that provide error-free connections. Class 4 is closest to TCP, although TCP contains functions, such as the graceful close, which OSI assigns to the session layer. Also, all OSI TP connection-mode protocol classes provide expedited data and preservation of record boundaries. Detailed characteristics of TP0-4 classes are shown in the following table


An easy way to visualize the transport layer is to compare it with a post office, which deals with the dispatch and classification of mail and parcels sent. Do remember, however, that a post office manages the outer envelope of mail. Higher layers may have the equivalent of double envelopes, such as cryptographic presentation services that can be read by the addressee only. Roughly speaking, tunneling protocols operate at the transport layer, such as carrying non-IP protocols such as IBM's SNA or Novell's IPX over an IP network, or end-to-end encryption with IPsec. While Generic Routing Encapsulation (GRE) might seem to be a network-layer protocol, if the encapsulation of the payload takes place only at endpoint, GRE becomes closer to a transport protocol that uses IP headers but contains complete frames or packets to deliver to an endpoint. L2TP carries PPP frames inside transport packet.

Although not developed under the OSI Reference Model and not strictly conforming to the OSI definition of the transport layer, the Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP) of the Internet Protocol Suite are commonly categorized as layer-4 protocols within OSI.

Layer 5: Session Layer

The session layer controls the dialogues (connections) between computers. It establishes, manages and terminates the connections between the local and remote application. It provides for full-duplex, half-duplex, or simplex operation, and establishes checkpointing, adjournment, termination, and restart procedures. The OSI model made this layer responsible for graceful close of sessions, which is a property of the Transmission Control Protocol, and also for session checkpointing and recovery, which is not usually used in the Internet Protocol Suite. The session layer is commonly implemented explicitly in application environments that use remote procedure calls.

Layer 6: Presentation Layer

The presentation layer establishes context between application-layer entities, in which the application-layer entities may use different syntax and semantics if the presentation service provides a big mapping between them. If a mapping is available, presentation service data units are encapsulated into session protocol data units, and passed down the protocol stack.

This layer provides independence from data representation (e.g., encryption) by translating between application and network formats. The presentation layer transforms data into the form that the application accepts. This layer formats and encrypts data to be sent across a network. It is sometimes called the syntax layer.

The original presentation structure used the Basic Encoding Rules of Abstract Syntax Notation One (ASN.1), with capabilities such as converting an EBCDIC-coded text file to an ASCII-coded file, or serialization of objects and other data structures from and to XML.

Layer 7: Application Layer

The application layer is the OSI layer closest to the end user, which means both the OSI application layer and the user interact directly with the software application. This layer interacts with software applications that implement a communicating component. Such application programs fall outside the scope of the OSI model. Application-layer functions typically include identifying communication partners, determining resource availability, and synchronizing communication. When identifying communication partners, the application layer determines the identity and availability of communication partners for an application with data to transmit. When determining resource availability, the application layer must decide whether sufficient network or the requested communication exists. In synchronizing communication, all communication between applications requires cooperation that is managed by the application layer. This layer supports application and end-user processes. Communication partners are identified, quality of service is identified, user authentication and privacy are considered, and any constraints on data syntax are identified. Everything at this layer is application-specific.










JOURNAL ARCHIVE: Posted by H.V.O.M at 10:40 AM Sunday, March 06, 2011


Who sent Deputy US Marshal Kerry Burgess to Asheville NC to be shot by gunfire?


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https://en.wikipedia.org/wiki/Illeism


Illeism

From Wikipedia, the free encyclopedia

Illeism (from Latin ille meaning "he, that") is the act of referring to oneself in the third person instead of first person.

Illeism is sometimes used in literature as a stylistic device. In real life usage, illeism can reflect a number of different stylistic intentions or involuntary circumstances.


In literature

Early literature such as Julius Caesar's Commentarii de Bello Gallico or Xenophon's Anabasis, both ostensibly non-fictional accounts of wars led by their authors, used illeism to impart an air of objective impartiality to the account, which included justifications of the author's actions. In this way personal bias is presented, albeit dishonestly, as objectivity.

Illeism can also be used in literature to provide a twist, wherein the identity of the narrator as also being the main character is hidden from the reader until later in the story (e.g. one Arsène Lupin story where the narrator is Arsène Lupin but hides his own identity); the use of third person implies external observation. A similar use is when the author injects himself into his own third-person-narrative story as a character, such as Charlie Kaufman in Adaptation, Douglas Coupland in JPod, and commonly done by Clive Cussler in his novels, beginning with Dragon. (There are also novels in which illeism may have been committed, but are not explicit, such the Traveller in H. G. Wells' The Time Machine, the identity of whom is often presumed to be Wells himself, as portrayed in the 1979 film Time After Time.)

It can also be used as a device to illustrate the feeling of "being outside one's body and watching things happen", a psychological disconnect resulting from dissonance either from trauma such as childhood physical or sexual abuse, or from psychotic episodes of actions that can't be reconciled with the individual's own self-image.

The same kind of objective distance can be employed for other purposes. Theologian Richard B. Hays writes an essay where he challenges earlier findings that he disagrees with. These were the findings of one Richard B. Hays, and the newer essay treats the earlier work and earlier author at arms' length.

A common device in science fiction is for robots, computers, and other artificial life to refer to themselves in the third person, e.g. "This unit is malfunctioning"










JOURNAL ARCHIVE: Posted by H.V.O.M at 6:07 PM Saturday, March 31, 2012


My mind.





A fairly new development are the mental images I have started to visualize.

I mean, sure, everyone, as is my understanding, most every human being has that capability.

The new development is comparable to when my so-called "foreign dreams" were plaguing my mind back in early 2006 and before that.

The clarity is the image is what's striking. And there doesn't seem to be any explanation. The sense is not unlike, I think as I sit here at my desk and write this sentence, my sleeping mind.

I feel that I have a very strong grip on reality. I think that some kind of ultranormal power of mind would require a strong sense of reality before it could develop in my mind.

I don't like fantasy, so that would probably explain why. I like the idea of getting to take a vacation and escape somewhere but the fact is, and I think this notion applies to most human beings, paradise gets boring after a while.


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JOURNAL ARCHIVE: - posted by H.V.O.M - Kerry Wayne Burgess 7:25 PM Pacific Time Spokane Valley Washington USA Sunday 13 September 2015 - http://hvom.blogspot.com/2015/09/fear-walking-dead.html


Fear the Walking Dead.



Vivid sleeping dreams again today earlier this morning.

A different kind of vivid dream though.

The kind of complex dream of complicated details that seem unimaginable for my own mind to produce.

There was nothing about the dreams I recall that reminded me of anything in my real life.

I don't recall the details now but I remember thinking while the visualizations were still fresh in my mind that I could not believe my mind could conjure up such details in those visualizations.

Not once today, until just now, did the thought occur to me about writing about those sleeping dreams.

All the other details are gone from my conscious mind although I was thinking about one specific dream sequence that was very compelling but that is now gone from my mind except for one visualization.

I can still visualize that scene to a certain degree. There seemed to be a boat involved. A person on the stern, who seemed to be partially in the water, released a winged horse into the sky. I thought about that later and my mind connected with the notion of Pegasus. That winged horse became motioned but it started off as something fixed in place, not a statue, but something stationary. I wish I could remember the other details.

New realizations form in my mind slowly over the days and weeks and months and I would instantly dismiss the possibilities as just another line of imaginative thought but then I think: I really have been doing magic lately. That stuff happened. What will happen next. Just is taking FOREVER!


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http://www.chakoteya.net/movies/movie8.html

Star Trek: First Contact (1996)


BORG QUEEN: Small words, from a small being, trying to attack what he doesn't understand.



- posted by H.V.O.M - Kerry Wayne Burgess 8:47 PM Pacific Time Spokane Valley Washington USA Sunday 06 December 2015