HTTPWhat is HTTP?History of HTTPWorld Wide Web Consortium (W3C)W3C GoalsHow HTTP WorksRequest MessageRequest LineRequest MethodsSlide 10Slide 11Status CodesBreak Down a URLURL ExampleWrap-UpQUESTIONS????HTTPHTTPBy:By:Becky Fultz, Joe Flager, Katie Becky Fultz, Joe Flager, Katie Huston, Tom Packard, Huston, Tom Packard, Allison WilseyAllison WilseyWhat is HTTP?What is HTTP?HyperText Transfer ProtocolInvented by Tim Berners-Lee in 1989Defines how messages are formatted and transmittedAlso, what actions web servers and browsers should take in response to different commandsHistory of HTTPHistory of HTTPTim Berners-Lee created the first server and hypertext browser/editor know as the “World Wide Web” in 1990In 1991 the “web” was made available on the internet by providing his previous creations of HTML, HTTP, and UDI (URL)This uniform code made it easy for everyone to be connected and “speaking” the same languageWorld Wide Web Consortium World Wide Web Consortium (W3C)(W3C)International Consortium created in 1994 by a group of individuals among whom included Tim Berners-LeeMission Statement: “To lead the World Wide Web to its potential by developing protocols and guidelines that ensure long-term growth for the web”Purpose is to create web standards and guidelines called the W3C recommendationsSince 1994 they have published more than 90 recommendationsW3C GoalsW3C Goals1. Web for Everyone2. Web on Everything3. Knowledge Base4. Trust and ConfidenceHow HTTP WorksHow HTTP WorksHTTP client sends a request using a transmission control protocol (TCP) connection to a port on a remote hostAn HTTP server connected to that port waits to receive the client’s message before it actsThe server sends back a status line The status line could be the requested file, an error message, or some other info–An example is HTTP/1.0 404 Not Found–Other users will see this errorThe HTTP server then closes the connection, known as Stateless ProtocolRequest MessageRequest MessageThe request message is sent from the client to the serverThe format for this message is as follows:–Request Line–Header–Empty Line–Optional Message BodyThe request line and headers must all end with CRLF (which stands for Carriage Return and Line Feed)Request LineRequest LineThe request line has 3 parts:–Method–Local path of the resource–HTTP VersionRequest MethodsRequest MethodsThere are 8 methods that indicate how the task is to be carried outGET: Request a representation of the specified resourceHEAD: Asks for the response identical to the one that would correspond to a GET request, but without the response body.Request MethodsRequest MethodsPOST: Submits user data to the identified resourcePUT: Uploads a representation of the specified resourceDELETE: Deletes the specified resourceOPTIONS: Returns the HTTP methods that the server supports.Request MethodsRequest MethodsCONNECT: For use with a proxy that can change to being an SSL tunnelTRACE: Echoes back the received request, so that a client can see what intermediate servers are adding or changing in the requestSafe methods are designed only for information retrieval. The methods are GET and HEADUnsafe methods are designed to make a user aware of possible side effects of their actions. These methods should be displayed in a special way such as a button.Status CodesStatus CodesStatus codes are informational groupings that are given by the server to the client as a status reportStatus codes are always three digits, and the first digits indicates what happened:1xx – informational message only2xx – indicated a success3xx – redirects the client to another URL4xx – indicates an error on the client’s part5xx – indicates an error on the server’s partSome common status codes are:202 means that everything went ok and the file is in the message body301 means that the file has been moved permanently 302 means that the file has been moved temporarily404 means that the file does not exist505 means an unexpected server errorBreak Down a URLBreak Down a URLURL - Uniform Resource Locator (This is a subset of URI, which is a uniform resource identifier)Unique address–File–Image–WebsiteContains:–Program used to access the resource–Specific computer that the file is stored in–File name of the resource including the path of how to get to itURL ExampleURL Examplehttp://en.wikipedia.org:80/wiki/Special:search?search=train&go=GoWrap-UpWrap-UpInvented in 1989 by Tim Berners-LeeHelped connect everyone by using the same languageVery complex and rigid