Midterm 1 Review Sheet CSS 305 Sp 06

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Darrell Bates
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1 This is a list of topics that we have covered so far. This is not all inclusive of every detail and there may be items on the exam that are not explicitly listed here, but these are the primary topics of interest. Basic terminology Software. Operating system, program, algorithm, Graphical User Interface (GUI), command line, web browser. Hardware. Parts of the computer like monitor, display, Cathode Ray Tube (CRT), Liquid Crystal Display (LCD), Red-Green-Blue (RGB), pixel, processor box (or case), motherboard (or system board), daughter board (or card), processor, microprocessor, memory, kilo (1 thousand), mega (1 million), giga (1 billion), hard disk, floppy disk, network interface. Software operation Basic metaphors like buttons, sliders, close boxes, menus, keyboard shortcuts, ellipsis (...) on a menu means more input required. Common program operations like file operations New, Open, Close, Save, Save As, print operations Page Setup, Print, Print Preview, program control operation Exit or Quit. Common editing operations like Undo, Repeat, Cut, Copy, Paste, Clear and Select All. An instance of a document. Feedback methods like input dialog boxes, message dialog boxes, dim menu items mean the command is unavailable. The ability to think about what you want the software to do, and list the operations that might be provided to accomplish that. In other words, have a strategy for exploring new applications or new capabilities of a familiar application. Networking Descriptive names like The Internet (the networking equipment and capabilities that connects a worldwide collection of computers), Local Area Network (LAN), Wide Area Network (WAN). Network packets and routing. Protocols are the rules by which packets (and the messages they represent) are routed and interpreted, Transmission Control Protocol / Internet Protocol (TCP/IP), File Transfer Protocol (FTP), Ethernet Protocol. Network addresses (or Internet Protocol addresses), dotted quad (four numeric values separated by. ), domain names (strings separated by. ), how to read a domain name (right to left moving down the hierarchy), translation from domain name to dotted quad by the Domain Name System (DNS) and the DNS servers that implement it. World Wide Web All the machines that implement HyperText Transport Protocol (HTTP) server software and the client browsers that access them. Not all the machines on the Internet participate in the Web; the Web is just one of the ways that information is passed around. Elements of a Uniform Resource Locator (URL) are: protocol specifier (eg, server computer name (specified as computer name plus domain name, or dotted quad), and pathname to the file on the server. Know how to DW Johnson Page 1 of 5

2 construct and read a pathname as we discussed in lab and in class. Client / server interaction to request and provide a particular page or service. HyperText Markup Language (HTML / XHTML) The language in which web pages are written. Plain text files with special structure defined by a limited set of tags. The file name extension is generally html or htm. The basic structure of an html page is <!DOCTYPE html format-definition...> <html> <head> <title>title text</title> <link href="name.css" rel="stylesheet" type="text/css" /> </head> <body> Body definition including text, images, tables, etc </body> </html> You should be able to read a straightforward html page. Know that the DOCTYPE entry defines the specific format of the html document. In this class, we are using xhtml format. Following the DOCTYPE is the actual body of the document, structured using opening and closing tags to define nested elements. The outermost element is the html element, defined using an opening <html> tag and a closing </html> tag, as above. Inside the html element are the head element and the body element. The head can contain several different elements, but the most important for us are the page title element and a link element pointing to the associated CSS style sheet. You should be able to read and write the pathnames that link an html file and a CSS file together. The body contains the actual content of the page that is rendered by the browser for viewing. Understand the purpose of the tags listed in the example above as well as <p> paragraph, <h1>, <h2>,, <h6> header, <div> block level grouping of content (eg, a complete paragraph or group of paragraphs), <span> inline grouping of content (eg, a word or a phrase), <a href=... > anchor reference (a link to another URL), <img src=..., alt= alt text > image reference. Note that some tags have required or optional attributes. In particular make sure you understand how the anchor and img tags are constructed. Understand how pathnames are constructed and how they relate to the directory structure on disk. The root of the file system is specified with a single /. Absolute pathnames start at the root and list each directory in the path to a particular subdirectory or file. Relative pathnames start at the current location (eg, the location of the web page containing the relative pathname) and list each directory in the path from there to the particular subdirectory or file. Know that.. means the parent directory, and that / is used to separate directories and filenames in a pathname. DW Johnson Page 2 of 5

3 Understand the use of the Validator service from the World Wide Web Consortium to check the structure of your web page against the associated definition given in the DOCTYPE. Know that the document type defines the syntax of the tags that you are using. Cascading Style Sheets (CSS) Know that styling of the text and images presented on a web page are best handled using a separate style sheet. The language that the style sheet is written in is called CSS. In the CSS file, you specify one or more selectors to pick out the elements in the HTML file to be formatted along with the properties and values that you want to apply to the selected element (or elements). The language for defining the selectors can be quite complex, but the basic selectors are the element type (body, div, span, h1, h2, img, p, a, ), a specific "id" given for an element (<div id="footer">), and the general "class" given for the element (<span class="familymember">). div#footer { font-family: sans-serif; h1 { color: green; span.familymember { font-weight: bold; selects <div id="footer"> selects <h1>introduction</h1> selects <span class="familymember"> You should be able to read and identify linkages between an HTML file and a CSS file. Review the lecture notes on XHTML and CSS (linked from the calendar page) for specific examples. Using the Web and searching for information Understand the idea of hierarchies as the traditional method of organizing information. Hierarchies are very valuable when the information is well understood and can be categorized definitively. Individual web sites are often organized in a hierarchical fashion, starting with a home page, then providing links to pages within the site for various categories of information. The linked pages then provide links to further refinements and so on. Understand the terminology of a hierarchy including the root (often drawn at the top), the leaves (the last entry in a series of increasingly detailed entries), drilling down (going from the general to the specific), moving up the hierarchy (going from the specific to the general). Search engines like Google and Yahoo give us another way to access large piles of information such as the unorganized information on the larger web, by providing a giant index that is referred to whenever you make a search request. The index is generated by crawling the web, which is done by software at the search company. Not all pages that are available on the web are indexed, not all pages in the index still exist. Effective use of a search engine entails thinking about DW Johnson Page 3 of 5

4 specific words that characterize the information you are looking for, understanding the flavor of the results that you get, and modifying the search to home in on the desired source. Changing the search terms or more advanced combinations of terms and qualifiers are used to control the results. Another important aspect of searching is making sure that the information you get is reliable. Anyone can publish a web page. The data that is presented has not been fact checked by anybody at all and may be a complete fabrication, a well meaning but incorrect statement, or the best answer possible. It s up to you to evaluate what you are looking at. Starting with known information sources is a good way to work when you have specific requirements. The UW library system has a rich set of resources to draw on and skilled librarians to help you with your search. The library web site provides access to many of their information sources, but not all. Finally, remember that the information on the web is only a small fraction of what is available in the real world. Get up and go talk to people when you want to explore a subject in depth. The world of information is deep and wide, and exploring it is a lot of fun! UW Computing Resources You should be familiar with the material in the labs related to dante, the primary student mainframe machine available through the UW. Understand the SSH Secure File Transfer program and what it is used for. Dante is connected to the UW network and you can easily move files from desktop machines to dante for file backup or serving on the web. The file structure on dante is a hierarchy that you should be able to navigate. For example, given a drawing representing several file directories, you should be able to write down pathnames that will identify various files or directories within that structure. The operating system on the desktop machines available to us is usually Windows XP or Mac OS X. You should know that they both have graphical user interfaces as well as command line interfaces that you can use to enter commands. Both of these operating systems have hierarchical file systems like the one on dante, although they differ in some of the details. There are text editor programs, word processing programs, and a large variety of other capabilities available on these systems. Numbers and Information Representation Computers represent information with numbers. The terms digitization and quantization mean representing information by any fixed set of symbols. The same numeric value can represent many different pieces of information depending on the context. There are numerous standards in use for representing common quantities. Text characters are often represented by relatively small numbers (0 to 255) with the ASCII encoding. However, this scheme cannot be used to represent all the languages that people use and so other schemes DW Johnson Page 4 of 5

5 have been invented, including Unicode that uses a larger range of numbers to represent more characters. Additional levels of encoding such as XML tags are used to describe structure or other higher-level (or meta-level) information about a data set. Colors are another quantity that is often represented numerically. In a simple monochromatic system (black, gray, white) the brightness of a particular pixel (picture element) is often represented with a single value in the range 0 to 255. In a more complex system, colors are usually represented using three brightness values, one each for Red, Green, and Blue, with each value selected from the range 0 to 255. Any information that can be characterized numerically (by digitizing it, ie, converting it to discrete values) can be represented in the memory of a computer. This is the basis of image and audio processing. As long as the program that stored the data and the program that reads the data agree on the organization of the numbers and what they represent, we can store whatever we want. One of the fundamental ideas associated with numbers is the concept of positional notation. For a particular number base, each position in a number (digit) can represent as many different values as the base. In other words, for a base 2 number, each position can represent one of two values. For a base 10 number, each position can represent one of ten different values. And for a base 16 number, each position can represent one of 16 different values. Consequently, in order to represent numbers in base two, only two different symbols are needed. Traditionally the symbols used are 0 and 1, although any two distinct symbols will suffice. In order to represent numbers in base 10, we traditionally use 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9. For base 16, we use the same 0 through 9, then add A, B, C, D, E, and F to represent 10 10, 11 10, 12 10, 13 10, 14 10, and Each column in a numeric value represents one more multiplication by the base value as the number of columns increases. Using positional notation and a fixed set of symbols, any number of different states can be identified. Different encodings can be used to represent the same set of states. Any phenomenon that can be set and measured can be used to encode state information. One very common encoding is to use presence and absence of some physical characteristic to encode binary bits. The word bit is a contraction of binary digit. A byte is a set of eight bits. 256 different states can be encoded in 8 bits because = 2 8 = 256. Inside the computer itself, numeric values are generally represented in base 2 binary numbers, since most computers operate on binary signals (either on or off, true or false, high or low, etc). However, a value is the same no matter what base it is expressed in. So, for example, if a computer stores the number in its memory, we can say that it is storing or without contradiction or loss of information. (By the way, this is the ASCII code for the number sign character #.) You should be able to convert a small binary (base 2) number or hexadecimal (base 16) number to base 10, and also be able to convert easily between base 2 and base 16 directly. Remember that four binary positions (bits) convert directly to one hexadecimal digit, and vice versa. DW Johnson Page 5 of 5

Final Exam Review Sheet INFO/CSE 100 Spring 2006

Final Exam Review Sheet INFO/CSE 100 Spring 2006 This is a list of topics that we have covered since midterm exam 2. The final will be cumulative, that is, it will cover material from the entire quarter,