Overview of what's going on in the HTTP world. This is the latest version of a talk I've given in the past at Google, Bell Labs and QCon San Francisco.
This document summarizes a lecture on computer networks and the hypertext transfer protocol (HTTP). It first reviews the early history of computer networking and the development of the world wide web. It then provides details on HTTP, including requests and responses, methods, status codes, and cookies. It discusses how caching works to improve performance by satisfying requests locally when possible. Methods like If-Modified-Since are described which check if a cached object has been updated before retrieving from the origin server.
HTTP is an application-layer protocol for transmitting hypermedia documents across the internet. It is a stateless protocol that can be used on any reliable transport layer. HTTP uses requests and responses between clients and servers, with common methods including GET, POST, PUT, DELETE. It supports features like caching, cookies, authentication, and more to enable the web as we know it.
How Time To First Byte (TTFB) Impacts Your Site’s PerformanceMedianova
Let’s all agree that your #website speed can be subject to many factors. While it’s hard to break down all of them, it’s still not impossible. In this context, one of the metrics you can try to interpret and improve is Time To First Byte (#TTFB).
HTTP is a protocol for transmitting hypermedia documents across the internet. It uses a client-server model where browsers make HTTP requests to web servers, which respond with HTTP responses. Key aspects of HTTP include using TCP/IP for communication, being stateless, supporting a variety of data types, and incorporating features of both FTP and SMTP protocols.
Genora has pioneered high end chat applications development using xmpp architechture. Here is a detailed report you need to know while developing chat applications.
Reach us at https://www.genorainfotech.com/
HTTP/2 is an updated protocol that improves upon HTTP/1.1 by allowing multiple requests to be sent simultaneously over a single TCP connection using multiplexing and header compression. It reduces latency compared to HTTP/1.1 by fixing the head-of-line blocking problem and prioritizing important requests. Key features of HTTP/2 evolved from the SPDY protocol and include multiplexing, header compression, prioritization, and protocol negotiation.
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HTTP was created in 1989 by Tim Berners-Lee at CERN to allow information sharing through hypertext. The first web server and website launched in 1990-1991. HTTP uses a client-server model with requests containing a start line with method, URL, and protocol version followed by headers and an optional message body. Responses contain a status line, headers, and body. Key concepts are persistent connections, caching, content types, and new versions that add functionality while maintaining backward compatibility.
HTTP is an application-level protocol for distributed, collaborative hypermedia systems that has been used by the World Wide Web since 1990. The initial HTTP/0.9 version provided a simple protocol for raw data transfer, while HTTP/1.0 introduced MIME-like messages to include meta information and request/response modifiers. HTTP/1.0 did not sufficiently account for hierarchical proxies, caching, persistent connections or virtual hosts. HTTP sits at the top of the TCP/IP stack and uses ports to carry protocols between services, with HTTP typically using port 80. An HTTP message is delivered over a TCP/IP connection by chopping the message into chunks small enough to fit in TCP segments, which are then sent inside IP datagrams
The Hypertext Transfer Protocol (HTTP) is an application layer protocol for distributed, collaborative, hypermedia information systems and is the foundation for data communication on the World Wide Web. HTTP defines methods like GET and POST to indicate the desired action on a resource and uses status codes in responses. It also uses headers in requests and responses to define parameters of the transaction. HTTP typically uses TCP port 80 to allow a client to open a connection and send requests to a server, which responds with messages that may contain requested resources or error information.
The web has dramatically evolved over the last 20+ years, yet HTTP - the workhorse of the Web - has not. Web developers have worked around HTTP's limitations, but:
--> Performance still falls short of full bandwidth utilization
--> Web design and maintenance are more complex
--> Resource consumption increases for client and server
--> Cacheability of resources suffers
HTTP/2 attempts to solve many of the shortcomings and inflexibilities of HTTP/1.1
HTTP (Hypertext Transfer Protocol) is the set of rules for transferring files between clients and servers on the World Wide Web. Communication occurs through HTTP requests from clients to servers and HTTP responses from servers to clients. A typical request/response cycle involves a browser requesting an HTML page from a server, which returns the page, and then the browser requesting and receiving additional files like stylesheets, images, and JavaScript code referenced in the HTML. An example is provided of an HTTP request from a browser to a server for a youtube.html page and the corresponding response.
1. The document describes the common HTTP methods used to retrieve or send data over the web, including GET, HEAD, POST, PUT, DELETE, CONNECT, OPTIONS, and TRACE.
2. GET is used to retrieve a resource, HEAD is like GET but only returns headers, and POST sends data to a server like form data or file uploads.
3. PUT replaces a resource with uploaded content, DELETE removes a resource, and CONNECT establishes a tunnel. OPTIONS returns supported methods and TRACE echoes a request for debugging.
This document provides an overview of HTTP including:
- HTTP is a stateless protocol that does not require servers to retain user information across requests.
- Popular HTTP proxy tools like Fiddler and Burp Suite can be used to inspect and debug HTTP traffic.
- Key parts of HTTP include requests methods, response codes, headers for accepting content types, encoding, authentication, and more.
- Common players that interact with HTTP include web servers, load balancers, caching servers, CDNs, and security tools.
HTTP is the set of rules for transferring data across the World Wide Web. It uses clients like web browsers to make requests to servers using URLs over TCP/IP. HTTP defines request and response messages with request methods like GET and POST and response status codes. HTTP 1.1 supports persistent connections and caching via proxy servers for improved performance over HTTP 1.0.
The document provides an overview of how a web server processes an HTTP request. Key steps include:
1) Receiving the request via a listening socket and parsing it to determine the requested file.
2) Checking permissions and metadata for the file via calls like stat().
3) Opening the file, generating a response, and sending the response headers and file contents to the client socket.
4) Optimizations focus on caching frequently accessed metadata and file data in memory to avoid repeated disk operations.
This document provides an overview of HTTP caching and content distribution networks. It begins with a review of HTTP and persistent connections. It then discusses how caching works in HTTP, including cache validation via If-Modified-Since headers and ETags. It describes how web proxies and content delivery networks can be used for caching. Finally, it explains how content distribution networks like Akamai replicate and distribute content to edge servers close to users for improved performance.
The document provides an overview of the Hypertext Transfer Protocol (HTTP) including its basic request/response message format, common methods like GET and POST, status codes, headers, entities, and chunked transfer encoding. HTTP began as a simple protocol to request and receive hypertext files but now supports a wide range of content and new features to power the modern web.
The HTTP protocol is an application-level protocol used for distributed, collaborative, hypermedia information systems. It operates as a request-response protocol between clients and servers, with clients making requests using methods like GET and POST and receiving responses with status codes. Requests and responses are composed of text-based headers and messages to communicate metadata and content. Caching and cookies can be used to improve performance and maintain state in this otherwise stateless protocol.
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A web server is software that responds to requests from web browsers to serve web pages. It is part of a multi-tier architecture with an information tier (database), middle tier (application logic), and client tier (user interface). The most common protocol for communication between clients and servers is HTTP, with the server responding to GET and POST requests with web pages or other responses. Popular web server software includes Apache, IIS, and Tomcat.
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3) Techniques web servers use like access control through authentication and authorization, passing data to scripts, using cookies, caching responses, and allocating resources through event-driven, process-driven, and hybrid architectures.
Performance Evaluation PowerPoint Slides include topics such as: 4 benefits and 11 additional values of performance appraisals, performance interviews, ground rules for performance evaluation, building performance contracts, developing work plans, setting the stage for a performance appraisal meeting, opening and closing your appraisal session, handling poor performance, conducting a feedback meeting, how to conduct a performance appraisal discussion, how to's and more. Slides can easily be tailored to your specific needs (make handouts, create overheads and use them with an LCD projector) and are available for license. 100+ PowerPoint presentation content slides. Each slide includes slide transitions, clipart and animation. System & Software Requirements: IBM or MAC and PowerPoint 97 or higher. Royalty Free - Use Them Over and Over Again. Once purchased, download instructions will be sent to you via email. (PC and MAC Compatible).
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// Project page
https://userinterfaces.aalto.fi/laas/
// Abstract
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// Keywords
Self-adaptive web interfaces, Web-based interaction, Web personalization, Web layouts, Web service architectures
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1. Performance Evaluation of
XMPP on the Web
Markku Laine and Kalle Säilä
Dept. Media Technology, Aalto University
Finland
T-106.4000 Laboratory Course in Software Techniques
Mini Conference
April 25, 2012
2. Presentation is about...
Real-time communication techniques on the Web
Extensible Messaging and Presence Protocol (XMPP)
Network performance evaluation
2
3. Presentation Outline
Introduction
Experiments
Results
Conclusions and future work
3
5. Extensible Messaging and Presence
Protocol (XMPP)
• XML-based, open-standard communications protocol for
real-time applications
– XMPP is an application-level protocol
• Originally developed for simple chat applications (users,
presence, and messages) under the name Jabber
– Now, over 300 XMPP Extension Protocols (XEPs) for a wide
variety of application scenarios (e.g., publish-subscribe, peer-to-
peer file transfer, and multi-user chat)
• Core standardized by the Internet Engineering Task
Force (IETF)
• Widely used outside the Web
5
6. XMPP Communication
• Decentralized client-server architecture
• Two-way, full-duplex channel between the client and the
server (two XML streams over a single TCP socket)
6
7. Three Different Techniques to use XMPP
on the Web
• Jabber HTTP Polling
(XEP-0025)
• XMPP over BOSH
(XEP-0206)
• XMPP sub-protocol
for WebSocket
7
8. Three Different Techniques to use XMPP
on the Web
• Jabber HTTP Polling {identifier};{key},!
<message to="{username}@{domain}">!
(XEP-0025) <body>{payload}</body>!
</message>!
<body rid="{rid}” sid="{sid}” key="{key}"
xmlns="http://jabber.org/protocol/httpbind">
• XMPP over BOSH <message to="{username}@{domain}">
<body>{payload}</body>
(XEP-0206) </message>
</body>!
• XMPP sub-protocol <message to="{username}@{domain}">!
<body>{payload}</body>!
for WebSocket </message>!
8
10. Setup
• Server: Ejabberd XMPP server running on a MacBook
Pro with a 64-bit OS X 10.6.8 operating system and a
2.53 GHz Intel Core 2 Duo CPU
• Client: Test clients running on an iMac with a 64-bit OS
X 10.6.8 operating system and a 2.4 GHz Intel Core 2
Duo CPU
– Browser: Safari 5.1.5
• Network: 100/100 Mbit/s Local Area Network (LAN)
– Maximum Frame Payload Size: 15928 bytes (Jumbo Frame)
• In general, the Maximum Ethernet Frame Size is 1500 bytes
10
11. Network Overhead
• Goal: Find out how much
example
network traffic overhead
<message to=”user@xmpp.org">
the techniques generate <body>hello world</body>
</message>
example
POST /http-bind HTTP/1.1
Host: ksaila.local:5280
Content-Type: text/xml; charset=UTF-8
11
12. Round Trip Rate
• Goal: Find out the maximum rate in which the client can
send messages to another client
• 30 test runs per technique per payload (10, 100, and
1000 bytes payload)
– 100 round trips per test run
– 100 ms polling interval with Jabber HTTP Polling
• Tests were performed as a round trip from a client to the
same client via the server (XMPP does not provide any
”message successfully delivered” information)
– The client was not allowed to send new messages before
receiving the previous message
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13. Message Receive Rate: Server to Client
• Goal: Find out the maximum rate in which a client can
receive messages from other clients
• 30 test runs per technique per payload (10, 100, and
1000 bytes payload)
– 10000 messages per test run
– 100 ms polling interval with Jabber HTTP Polling
• The messages were sent from a native XMPP client
running on the server host machine (the traffic was
monitored during the test runs to make sure that the
send rate was way above the receive rate)
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26. Bottlenecks
• Polling
– Multiple messages sent within a single frame
• BOSH
– Multiple messages sent within a single frame
– Messages sent only after receiving a new request
• WebSocket
– Messages sent one per frame
• Transmitted message payload size
• Underlying network
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28. Conclusions
• HTTP ≠ real-time protocol
• XMPP = real-time protocol (outside the Web)
• Techniques to use XMPP on the Web
1) Jabber HTTP Polling
2) XMPP over BOSH
3) XMPP sub-protocol for WebSocket
• Polling generates unnecessary network traffic
• Polling and BOSH can send multiple messages within a
single frame
• WebSocket’s advantages are permanent TCP
connection and extremely low overhead
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29. Future Work
• Conduct an in-depth comparison of HTTP and XMPP
• Analyze real-world Web applications to obtain
– Use cases & requirements
• Expand experiments to cover
– 10000 bytes message payload
– Different network environments (incl. wired and wireless)
– Secure connections
– Server CPU usage
• Automate test runs
• Evaluate in different real-world settings with real-world
Web applications
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30. Related Work
• Gutwin, C. et al. “Real-Time Groupware in the Browser:
Testing the Performance of Web-Based Networking”. In
Proceedings of CSCW’11, pages 167-176, 2011.
• Pohja, M. “Server Push for Web Applications via Instant
Messaging”. In Journal of Web Engineering, Vol. 9, No.
3, pages 227-242, 2010.
• Griffin, K. and Flanagan, C. “Evaluation of Asynchronous
Event Mechanisms for Browser-Based Real-Time
Communication Integration”. In Proceedings of
TDNEA’10, pages 461-466, 2010.
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31. Thank you for your attention!
Markku Laine Kalle Säilä
M.Sc. (Tech.), Ph.D. student B.Sc. (Tech.), M.Sc. student
markku.laine@aalto.fi kalle.saila@aalto.fi
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