Enter the url, web page to fully open?
First read cache, search your DNS cache, find the IP address directly access
1.DNS resolved
by the DNS server to resolve a domain name corresponding to the IP address of the server to be
2.TCP connection
know the server after the IP, the protocol requires three-way handshake to establish a connection, sends three packets
to confirm both the sending and receiving capabilities are normal, specify your own initialization sequence numbers
essence connect to the server specified port, TCP connection is established, the serial number of simultaneous connections on both sides and confirmation number
to start the client: closed server: the listen
1. the first handshake
client sends a SYN packet and indicate their initialization sequence number ISN to the server
client enters SYN_SENT state
with part of the header SYN = 1, initial the X-number = seq
SYN segment = 1 can not carry data, but it needs to consume a No.
2. the second handshake
after the server receives a client's SYN packet to its own SYN packets as a response
to specify your own initialization sequence No. ISN (s), the client ISN + 1 as the value of ACK
this time server SYN_RCVD state
Segment acknowledgment packet SYN = 1, ACK = 1, an acknowledgment number ack = x + 1, Y = initial sequence number SEQ
4. third handshake
after the client receives SYN segment, continues to send an ACK packet, the value of ISN + 1 to the server
the server in the ESTABLISHED state
after the server receives the ACK packet also enters the ESTABLISHED state
acknowledgment segment ACK = 1, an acknowledgment number ack = y + 1,. 1 + X = number SEQ
ACK segment may carry data, the data is not consumed number not carry
3. send request
HTTP request
4. Accept response
server accepts the request and returns the HTTP packet
5. the server process determines whether the code according to the normal state is returned
6. browser to render the page
return after the success of the code to get the browser requests a page, it parses out the renderer
1.HTML mark
calling HTML parser to build a DOM tree and Token
2.style/link mark
invoked CSS parser handle CSS markup and build CSSOM tree
3.script mark
JS parser calls, deal with JS code, binding events, modify the DOM tree and CSSOM tree
will be merged into a tree two tree rendering
is calculated based on the layout of the render tree, each node to calculate the geometric information
to draw a page based on the calculated information
7. disconnect
Similarly disconnect a connection requires four waved
1. the first wave (client: I think disconnected)
client sends a FIN packet, the packet sequence number specified in a
client in FIN_WAIT1 the state
is sending a connection release segment (FIN = 1, number seq = u)
to stop sending data, take the initiative to close the connection
2. The second wave (the server: do you want to disconnect it)
after the server receives FIN, will sends an ACK packet, and the sequence number value of +1 as the client ACK packet sequence number of
the server in the CLOSE_WAIT status
is sent after the server receives a connection release segment acknowledgment segment
TCP half-closed, connection release
client after receiving confirmation service terminal, enter FIN_WAIT2 state
waiting for the server makes a connection release segment
3. Third Wave (server: I would like disconnected)
server also want to disconnect, and sends FIN packets to the client to specify a serial number
server in LAST_ACK state
4. Fourth Wave ( client: initiating a confirmation)
after the client receives FIN, as sends an ACK packet as a response, the server sequence number value as the sequence number value of their own +1 ACK packet
client TIME_WAIT state, to ensure that the server received own ACK packet will enter CLOSED state
