INTRODUCTION:
HTTP stands for Hyper text transfer protocol .Before i will go into Http , let me explain what is protocol? In computer world protocol it is more or less like the manners or rule how computer layers or components interact with each other.When visiting Web sites, the client application makes connections to Web servers via a network protocol called HTTP. These network connections support sending response data from servers back to clients including the content of Web pages and also some protocol control information.
EXPLANATION
There is big/complex model made of 7 layers known as OSI Model as shown below
HTTP is just a small piece this model. So, lets what each word denotes in HTTP acronym. The T and the P together are the transfer protocol and HT, or hypertext, is the something that gets transferred with this protocol. Being more specific about hypertext, it is just when you create webpage and put come links for connecting/jump from one page to another. So, this hypertext needs to fallow some convention or rules.On the other side of the network we essentially have nothing more than your computer but instead of a browser with another piece of software, a web server. Of course, that computer also has HTTP installed. Here the protocol is linked with this web server software which will get the request and according to it will answer with a response. This response, again according to the rules set in the protocol, will be send back to your computer where the browser will understand what is going on and present the response to you.
HTTP (Hypertext Transfer Protocol) is the most popular application protocol used in the Internet
HTTP is an asymmetric request-response client-server protocol . An HTTP client sends a request message to an HTTP server. The server, in turn, returns a response message.
HTTP is a stateless protocol means the current request does not know what has been done in the previous requests.
Whenever you issue a URL from your browser to get a web resource using HTTP, e.g.
http://www.shabirhakim.net/index.html, the browser turns the URL into a request message
and sends it to the HTTP server. The HTTP server interprets the
request message, and returns back you an appropriate response message, which
is either the resource you requested or an error message. This process
is illustrated below:
Uniform Resource Locator (URL)
A URL (Uniform Resource Locator) is used to uniquely identify a resource over the web. URL has the following syntax:protocol://hostname:port/path-and-file-name
There are 4 parts in a URL:- Protocol: The application-level protocol used by the client and server, e.g., HTTP, FTP, and telnet.
- Hostname: The DNS domain name (e.g.,
www.shabirhakim.net) or IP address (e.g., 192.128.1.2) of the server. - Port: The TCP port number that the server is listening for incoming requests from the clients.
- Path-and-file-name: The name and location of the requested resource, under the server document base directory.
HTTP Request Methods
HTTP protocol defines a set of request methods. A client can use one of these request methods to send a request message to an HTTP server. The methods are:
GET: A client can use the GET request to get a web resource from the server.
HEAD: A client can use the HEAD request to get the header that a GET request would have obtained. Since the header contains the last-modified date of the data, this can be used to check against the local cache copy.
POST: Used to post data up to the web server.
PUT: Ask the server to store the data.
DELETE: Ask the server to delete the data.
TRACE: Ask the server to return a diagnostic trace of the actions it takes.
OPTIONS: Ask the server to return the list of request methods it supports.
CONNECT: Used to tell a proxy to make a connection to another host and simply reply the content, without attempting to parse or cache it. This is often used to make SSL connection through the proxy.
Response Status Code
The first line of the response message (status line) contains the response status code, which is generated by the server to indicate the result of the request.
The status code is a 3-digit number:
1xx (Informational): Request received, server is continuing the process.
2xx (Success): The request was successfully received, understood, accepted and serviced.
3xx (Redirection): Further action must be taken in order to complete the request.
4xx (Client Error): The request contains bad syntax or cannot be understood.
5xx (Server Error): The server failed to fulfill an apparently valid request.
COMMONLY ENCOUNTERED STATUS CODE:
100 Continue: The server received the request and in the process of giving the response.
200 OK: The request is fulfilled.
301 Move Permanently: The resource requested for has been permanently moved to a new location. The URL of the new location is given in the response header called Location. The client should issue a new request to the new location. Application should update all references to this new location.
302 Found & Redirect (or Move Temporarily): Same as 301, but the new location is temporarily in nature. The client should issue a new request, but applications need not update the references.
304 Not Modified: In response to the If-Modified-Since conditional GET request, the server notifies that the resource requested has not been modified.
400 Bad Request: Server could not interpret or understand the request, probably syntax error in the request message.
401 Authentication Required: The requested resource is protected, and require client’s credential (username/password). The client should re-submit the request with his credential (username/password).
403 Forbidden: Server refuses to supply the resource, regardless of identity of client.
404 Not Found: The requested resource cannot be found in the server.
405 Method Not Allowed: The request method used, e.g., POST, PUT, DELETE, is a valid method. However, the server does not allow that method for the resource requested.
408 Request Timeout:
414 Request URI too Large:
500 Internal Server Error: Server is confused, often caused by an error in the server-side program responding to the request.
501 Method Not Implemented: The request method used is invalid (could be caused by a typing error, e.g., "GET" misspell as "Get").
502 Bad Gateway: Proxy or Gateway indicates that it receives a bad response from the upstream server.
503 Service Unavailable: Server cannot response due to overloading or maintenance. The client can try again later.
504 Gateway Timeout: Proxy or Gateway indicates that it receives a timeout from an upstream server.
Finally ,
CONCLUSION :
HTTP is an application-level protocol for distributed, collaborative, hypermedia information systems. It is a generic, stateless, protocol which can be used for many tasks beyond its use for hypertext, such as name servers and distributed object management systems, through extension of its request methods, error codes and headers. A feature of HTTP is the typing and negotiation of data representation, allowing systems to be built independently of the data being transferred
PROTOCOLS WITH RESPECTIVE FAMILIES
| Protocol | Family |
| (ISO8073) A1 A10 A11 A12 A13 A14 A15 A3 A7 A8 A9 AAL2(Offline) AARP Abis Abis ACSE ADSP AEP AFP AH AH AMR AppleArp AppleTalk ARP/RARP ASP ATCP ATMCell(AAL0-AAL5) ATMCellNNI ATMCellUNI ATMCircuitEmulation ATMP ATMSAR ATP AVAYA(Skinny) BACP Banyan BAP BCAST BCC BCC BCP BGMP BGP-4 BICC B-ICI B-ISUP BMC BMP BPDU BSD BSMAP BSSAP BSSAP+ BSSAP+ BSSGP BSSMAP BTSM BTSM/LAPD BVCP CAMEL CAMEL Cascade CC CC CC CCP CDP CHAP CIF CiscoISL CiscoRouter CiscoSRB CMIP COPS CTERM DAP DCAP DDP DEC_LANBridge DEC_LAT DEC_LAVC DEC_MOP_D/L DEC_MOP_RC DEC_Route DESE DHCP DHCPv6 DIAG DIS DISL DLSw DNCP DNS DriP DSMCC DTAP DUP DVB DVMRP EAP ECP EGP EIGRP ELCP ES-IS ESP ESP Ethernet EtherTalk FANP FDDI Finger FP FrameRelay FrameRelayOverATM FrameRelayOverLAPF FrameRelayOverLLC FrameRelayOverSNA FRF.9(DCP) FRF10 FRF11 FRF12 FRF16 FRF4 FRF5 FRF8 FTAM FTP FUNI G711 G723.1 G729 GARP GCC GCC GCP GMM/SM GMM/SM GMRP GOPHER GR-303(IDLC/LAPD) GRE GSMP GTP GTP GTP' GVRP H.225 H.235 H.245 H.261 H.263 H.450.1 H.450.10 H.450.11 H.450.12 H.450.2 H.450.3 H.450.4 H.450.5 H.450.6 H.450.7 H.450.8 H.450.9 H225G H225G HDLC HPR-APPN HSRP HTTP ICMP ICMPv6 ICP ICPv2 IDLC IDP IDRP IDRP IFMP IGMP IGRP IISP ILMI IMAP4 IMPP INAP IP IPARSEoverX.25overLAPB IPC IPCP IPDC IPOverATM IPOverHDLC IPv6 IPv6CP IPX IPXCP IRC ISAKMP/IKE ISDN IS-IS ISL ISO-IP(CLNP) ISOoverX.25 ISO-PP ISO-SP ISO-TP ISUP ITUQ2931 ITUQ2971 IuUP L2F L2TP LAPB LAPD LAPF LAPV5 LAPV5DL LAT LAVC LCP LDAP LDP LE802.3 LE802.5 LEControl LES(PSTN) LEX LEXCP LLC LLC LQR LZS M2PA M2UA M3UA MAC MAP MAP MAPOS MARS MDLP MDTP Megaco(ASCII+ASN.1) Megaco(H.248) MegacooverATM MGCP MLP MM MM MM MMS MNRP MNTv1 MobileIP MOP MOUNT MPEG-2 MPLS MPLSoverATM MPPC MTP-2 MTP-3 MTP3B MultiPPP MZAP NARP NBAP NBFCP NBP NCP NDS NetBIOS NetBIOS/IP NetRPC NFS NHDR NHRP NHRP NLM NLP NLSP NNIPVC NNISVC NovelNetBIOS NS NSM NSP NSP NTP O&M OSINLCP OSPF PAP PAP PDCP PEP PIM PMAP PNNIRouting PNNISignaling POP3 PPP PPP-BPDU PPPMultilink PPPoE PPPoverATM PPPoverHDLC PPPoverLAPB PPPoverLAPF PPTP Proteon PROXY(Skinny) Q.2140 Q.2140 Q.SAAL Q2630 QLLC Radius RANAP RAS Rexec RIP RIP2 RIPngforIPv6 RIPX RLC RLC/MAC Rlogin RLP RLP RND RNSAP ROSE RP RPC RPCB RPCB Rprint RR RR RR RRC Rshell RSVP RTCP RTMP RTP RTP RTSP RUDP RVPoverIP Rwho SAMOverFREther SAMOverX.25OverLAPB SAP SAPv2 SCCP SCP SCSP SCTP SCTP SDCP SDCP SDLC SDP SER SGCP SIP SIP-L3 Skinny SLP SMB SMPP SMS SMS SMS SMS(TP) SMS(TP) SMSCB SMS-CB SMSCB SMT SMTP SNA SNA5250 SNACP SNAoverSDLC SNAP SNARH SNATerminology SNATH SNATHO-THS SNDCP SNDCP SNDCP SNMP SOCKS SPANS SPANS SPP SPP SPX SRP SS SS SS SSP STP StreetTalk T.125 T.38 TACACS+ TALI TCAP TCP TDP TELNET TFTP THDR Timeplex(BRE2) TokenRing TOM TPKT TRAU TRIP TUP UDP UNI3.x UNI4.0 UNISVC V5 V5-BCC V5-Control V5-LinkControl V5-Protection V5-PSTN VanJacobson VARP VB51 VIP VIVIDarm VIVIDbme VIVIDccp ViVIDMPOA VLAN(802.1Q) VRRP VTP WCCP WCMP WDOG WDP Wellfleet WSP WTLS WTP X.25 X.75 XOT X-Window YP(NIS) ZIP |
ISO CDMA2000 CDMA2000 CDMA2000 CDMA2000 CDMA2000 CDMA2000 CDMA2000 CDMA2000 CDMA2000 CDMA2000 CDMA2000 ATM AppleTalk Cellular GPRS ISO AppleTalk AppleTalk AppleTalk IPSecurity TCP/IP UMTS AppleTalk AppleTalk TCP/IP AppleTalk PPP ATM ATM ATM Audio/VisualOver ATM TCP/IP ATM AppleTalk VoIP PPP Banyan PPP Novell GPRS UMTS PPP TCP/IP TCP/IP SS7 ATMSignaling&Routing ATMSignaling&Routing UMTS Novell Bridge/Router PPP Cellular Cellular GPRS UMTS GPRS Cellular Cellular Cellular PPP GPRS UMTS FrameRelay Cellular GPRS UMTS PPP Bridge/Router PPP LANDataLinkLayer Bridge/Router Bridge/Router Bridge/Router ISO TCP/IP DECnet DECnet TCP/IP AppleTalk DECnet DECnet DECnet DECnet DECnet DECnet PPP TCP/IP TCP/IP Novell LANDataLinkLayer Bridge/Router IBM PPP TCP/IP Bridge/Router Audio/VisualOverATM Cellular SS7 Audio/VisualOverATM TCP/IP PPP PPP TCP/IP TCP/IP VoDSL ISO IPSecurity TCP/IP LANDataLinkLayer AppleTalk TCP/IP LANDataLinkLayer TCP/IP UMTS FrameRelay FrameRelay FrameRelay FrameRelay FrameRelay FrameRelay FrameRelay FrameRelay FrameRelay FrameRelay FrameRelay FrameRelay FrameRelay ISO TCP/IP FUNI VoIP VoIP VoIP LANDataLinkLayer GPRS UMTS UMTS GPRS UMTS LANDataLinkLayer TCP/IP GR-303 TCP/IP IPSwitching GPRS UMTS UMTS LANDataLinkLayer H.323 H.323 H.323 H.323 H.323 H.323 H.323 H.323 H.323 H.323 H.323 H.323 H.323 H.323 H.323 H.323 H.323 H.323 H.323 X.25 IBM TCP/IP TCP/IP TCP/IP TCP/IP TCP/IP TCP/IP GR-303 XNS ISO TCP/IP IPSwitching TCP/IP TCP/IP ATMSignaling&Routing ILMI TCP/IP TCP/IP SS7 TCP/IP X.25 Banyan PPP TCP/IP ATM X.25 TCP/IP PPP Novell PPP TCP/IP IPSecurity ISDN ISO TagSwitchingr ISO ISO ISO ISO ISO SS7 ATMSignaling&Routing ATMSignaling&Routing UMTS TCP/IP TCP/IP X.25 ISDN FrameRelay V5.1/V5.2 VoDSL DECnet DECnet PPP TCP/IP TCP/IP LANEmulation LANEmulation LANEmulation VoDSL PPP PPP GPRS LANDataLinkLayer PPP PPP Sigtran Sigtran Sigtran UMTS GPRS UMTS Bridge/Router TCP/IP CDPD TCP/IP TCP/IP VoIP VoIP VoIP X.25 Cellular GPRS UMTS Cellular CDPD SUN TCP/IP DECnet SUN Audio/VisualOverATM TagSwitchingr TagSwitchingr PPP SS7 SS7 UMTS PPP TCP/IP TCP/IP UMTS PPP AppleTalk Novell Novell IBM TCP/IP Banyan SUN IBM IBM TCP/IP SUN IBM Novell FrameRelay FrameRelay Novell GPRS SUN Bridge/Router DECnet TCP/IP Cellular PPP TCP/IP AppleTalk PPP UMTS XNS TCP/IP SUN ATMSignaling&Routing ATMSignaling&Routing TCP/IP PPP PPP PPP PPP PPP PPP PPP PPP TCP/IP Bridge/Router VoIP ATMSignaling&Routing SS7 ATMSignaling&Routing UMTS IBM TCP/IP UMTS H.323 UNIX XNS TCP/IP TCP/IP Novell UMTS GPRS UNIX Cellular UMTS Bridge/Router UMTS ISO DECnet SUN SUN SUN UNIX Cellular GPRS UMTS UMTS UNIX TCP/IP H.323 AppleTalk Banyan H.323 TCP/IP TCP/IP VoIP UNIX FrameRelay X.25 Novell VoIP SS7 DECnet TCP/IP Sigtran TCP/IP PPP TCP/IP IBM VoIP Novell VoIP VoIP SMDS VoIP TCP/IP IBM TCP/IP Cellular GPRS UMTS GPRS UMTS Cellular GPRS UMTS LANDataLinkLayer TCP/IP IBM IBM PPP IBM LANDataLinkLayer IBM IBM IBM IBM CDPD GPRS UMTS TCP/IP TCP/IP ATMSignaling&Routing ATMSignaling&Routing Banyan XNS Novell LANDataLinkLayer Cellular GPRS UMTS Bridge/Router DECnet Banyan H.323 H.323 TCP/IP Sigtran SS7 TCP/IP TagSwitchingr TCP/IP TCP/IP IBM FrameRelay LANDataLinkLayer GPRS H.323 Cellular TCP/IP SS7 TCP/IP ATMSignaling&Routing ATMSignaling&Routing FrameRelay V5.1/V5.2 V5.1/V5.2 V5.1/V5.2 V5.1/V5.2 V5.1/V5.2 V5.1/V5.2 TCP/IP Banyan VB51 Banyan VIVID VIVID VIVID ATMSignaling&Routing LANDataLinkLayer TCP/IP Bridge/Router TCP/IP WAP Novell WAP Bridge/Router WAP WAP WAP X.25 X.25 TCP/IP TCP/IP SUN AppleTalk |
| AppleTalk | AppleArp, AppleTalk, EtherTalk, AARP, ADSP, AEP, AFP, ASP, ATP, DDP, NBP, PAP, RTMP, ZIP |
| ATM | ATM
Cell (AAL0-AAL5), ATM Cell NNI, ATM Cell UNI, ATM
SAR, IP Over ATM, AAL2 |
| ATM Signaling & Routing | ITU
Q2931, ITU Q2971, B-ICI, B-ISUP, IISP, PNNI Routing, PNNI Signaling, Q.2140, Q.SAAL, SPANS, UNI 3.x, UNI 4.0, ViVID MPOA, SPANS |
| Audio/Visual Over ATM | ATM
Circuit Emulation, DSMCC, DVB, MPEG-2 |
| Banyan | Banyan,
IPC, NetRPC, RTP, SPP, StreetTalk, VARP, VIP |
| Bridge/Router | BPDU, CDP, Cisco ISL, Cisco HDLC (cHDLC), Cisco SRB, DISL, DRiP, MAPOS, NSP, Proteon, RND, SSP, VTP, Wellfleet |
| CDMA2000 | A1, A3, A7, A8, A9, A10, A11, A12, A13, A14, A15 |
| CDPD | MDLP, MNRP, SNDCP |
| Cellular | Abis, BSMAP, BSSAP, BSSMAP, BTSM, BTSM/LAPD, CC, DTAP, MM, O & M, RR, RLP, SMS, SMSCB, TRAU, MMS, SS |
| DECnet | CTERM,
DAP, DEC_LANBridge, DEC_LAT, DEC_LAVC, DEC_MOP_D/L, DEC_MOP_RC, DEC_Route, LAT, LAVC, MOP, NSP, RP, SCP, STP |
| Frame Relay | Cascade,
Frame Relay, Frame Relay Over ATM, Frame Relay Over
LAPF, Frame Relay Over LLC, Frame Relay Over SNA,
FRF4, FRF5, FRF8, FRF.9 (DCP), FRF10, FRF11, FRF12, FRF16, LAPF, NNI PVC, NNI SVC, SAM Over FREther, Timeplex (BRE2), UNI SVC |
| FUNI | FUNI |
| GPRS | Abis,
BCC, BSSAP+, BSSGP, CAMEL, CC, GCC, GMM/SM, GTP, LLC, MAP, MM, NS, RR, RLC/MAC, SMS, SMS(TP), SMS-CB, SNDCP, SS, TOM |
| GR-303 | IDLC, GR-303 (IDLC/LAPD) |
| H.323 | H.225,
H.235, H.245, H.261, H.263, H225G, H.450.1, H.450.10,
H.450.11, H.450.12, H.450.2, H.450.3, H.450.4, H.450.5, H.450.6, H.450.7, H.450.8, H.450.9, H225G, RAS, RTCP, RTP, T.125, T.38, TPKT |
| IBM | DLSw,
HPR-APPN, NetBIOS, NHDR, NHRP , NLP, QLLC, SDLC,
SMB, SNA, SNA 5250, SNA over SDLC, SNA Terminology, SNARH, SNATH, SNA THO-THS, THDR |
| ILMI | ILMI |
| IP Security | AH, ESP, ISAKMP/IKE |
| IP Switching | GSMP, IFMP |
| ISDN | ISDN, LAPD |
| ISO | ACSE,
CMIP, ES-IS, FTAM, IDRP, IS-IS, ISO-IP (CLNP), ISO-PP, ISO-SP, ISO-TP, (ISO 8073), ISO over X.25, ROSE |
| LAN Data Link Layer | CIF,
DIS, Ethernet, FDDI, GARP, GMRP, GVRP, LLC, SMT, SNAP, SRP, Token Ring, VLAN (802.1Q) |
| LAN Emulation | LE 802.3, LE 802.5, LE Control |
| Novell | BCAST,
BMP, DIAG, IPX, NCP, NDS, NLSP, Novel NetBIOS, RIPX, SAP, SER, SPX, WDOG |
| PPP | ATCP,
BACP, BAP, BCP, BSD, BVCP, CCP, CHAP, DESE, DNCP, EAP, ECP, IPCP, IPv6CP, IPXCP, LCP, LEX, LEXCP, LQR, LZS, MPPC, Multi PPP, NBFCP, OSINLCP, PAP, PPP, PPP Multilink, PPP-BPDU, PPP over ATM, PPP over LAPB, PPP over LAPF, PPP over HDLC, PPPoE, SDCP, SNACP |
| Sigtran | M2PA, M2UA, M3UA, SCTP, TALI |
| SMDS | SIP-L3 |
| SS7 | BICC,
DUP, INAP, ISUP, MTP-2, MTP-3, Q.2140, SCCP, TCAP, TUP |
| SUN | MOUNT,
MNTv1, NFS, NLM, NSM, PMAP, RPC, RPCB, RPCB, YP (NIS) |
| Tag Switching | ISL, MPLS, MPLS over ATM, TDP |
| TCP/IP | AH,
ARP/RARP, ATMP, BGMP, BGP-4, COPS, DCAP, DHCP, DHCPv6, DNS, DVMRP, EGP, EIGRP, ESP, FANP, Finger, FTP, GOPHER, GRE, HSRP, HTTP, ICMP, ICMPv6, ICP, ICPv2, IDRP, IGMP, IGRP, IMAP4, IMPP, IP, IPv6, IPDC, IRC, L2F, L2TP, LDAP, LDP, MARS, MDTP, Megaco (ASCII + ASN.1), Mobile IP, MZAP, NARP, NetBIOS/IP, NHRP, NTP, OSPF, PIM, POP3, PPTP, Radius, RIP2, RIPng for IPv6, RSVP, RTSP, RUDP, SCSP, SCTP, SDCP , SLP, SMPP, SMTP, SNMP, SOCKS, TACACS+, TCP, TELNET, TFTP, TRIP, UDP, Van Jacobson, VRRP, WCCP, XOT, X-Window |
| UMTS | AMR, BCC, BSSAP+, CAMEL, CC, FP, GCC, GMM/SM, GTP, GTP', GCP, MAC, MAP, MM, NBAP, PDCP, Q2630, RANAP, RLC, RLP, RNSAP, RRC, SMS, SMS(TP), SNDCP,IuUP, SMSCB, BMC, MTP3B, RR, SS |
| UNIX | Rexec,
Rlogin, Rprint, Rshell, Rwho |
| V5.1/V5.2 | LAPV5,
V5, V5-BCC, V5-Control, V5-Link Control, V5-Protection, V5-PSTN |
| VB51
|
VB51 |
| VIVID
|
VIVIDarm, VIVIDbme, VIVIDccp |
| VoDSL |
ELCP, LAPV5DL, LES-PSTN, (VoATM) |
| VoIP | AVAYA (Skinny), G729, G723.1, G711, Megaco (H.248),
Megaco over ATM, MGCP, PROXY (Skinny), RVP over IP, SAP v2, SDP, SIP, Skinny, SGCP |
| WAP | WCMP, WDP, WSP, WTLS, WTP |
| X.25 | HDLC,
IP Over HDLC, IPARSE over X.25 over LAPB, LAPB, MLP, SAM Over X.25 Over LAPB, X.25, X.75 |
| XNS | IDP, PEP, RIP, SPP |
REFERENCES & RESOURCES
- W3C HTTP specifications at http://www.w3.org/standards/techs/http.
- RFC 2616 "Hypertext Transfer Protocol HTTP/1.1", 1999 @ http://www.ietf.org/rfc/rfc2616.txt.
- RFC 1945 "Hypertext Transfer Protocol HTTP/1.0", 1996 @ http://www.ietf.org/rfc/rfc1945.txt.
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