Tag Archives: http

HTTP Long Polling

Web applications were originally developed around a client/server model, where the Web client is always the initiator of transactions, requesting data from the server. Thus, there was no mechanism for the server to independently send, or push, data to the client without the client first making a request.

To overcome this deficiency, Web app developers can implement a technique called HTTP long polling, where the client polls the server requesting new information.  The server holds the request open until new data is available. Once available, the server responds and sends the new information. When the client receives the new information, it immediately sends another request, and the operation is repeated. This effectively emulates a server push feature. 

Considerations for HTTP Long Polling

There are a couple of things to consider when using HTTP long polling to build realtime interactivity in your application, both in terms of developing and operations/scaling.

  • As usage grows, how will you orchestrate your realtime backend?
  • When mobile devices rapidly switch between WiFi and cellular networks or lose connections, and the IP address changes, does long polling automatically re-establish connections?
  • With long polling, can you manage the message queue and catch up missed messages?
  • Does long polling provide load balancing or failover support across multiple servers?

When building a realtime application with HTTP long polling for server push, you’ll have to develop your own communication management system. This means that you’ll be responsible for updating, maintaining, and scaling your backend infrastructure.

Backend Infrastructure for Realtime Functionality

With these considerations in mind, that’s where a realtime data stream network comes in. This data stream network takes care of the backend infrastructure for you, so you don’t have to worry about maintaining and orchestrating your realtime network.

When looking at HTTP long polling with the goal of streaming data, PubNub is a low-latency and low-overhead realtime Web app communication environment, and features the ability to send messages to a single client, client groups and all clients. Upgrading to PubNub is both rapid and easy since it is based on a publish/subscribe model.

Key Benefits of Protocol Agnostic Realtime Messaging

Instead of relying solely on HTTP long polling for realtime messaging, a protocol-agnostic approach is beneficial. PubNub automatically chooses the best protocols and frameworks depending on the environment, latency, etc. Any server or client code wanting to communicate makes a single API call to publish or subscribe to data channels.

The code is identical between clients and servers, making implementation much simpler than using HTTP long polling. In terms of connection management, the network handles network redundancy, routing topology, loading balancing, failover, and channel access. Additionally, it offers core building blocks for building realtime into your application.

  • Presence – Detect when users enter/leave your app and whether machines are online
  • Storage & Playback – Store realtime message streams for future retrieval and playback
  • Mobile Push Gateway – Manage the complexities of realtime apps on mobile devices, including Push Notifications
  • Access Management – Fine grain Publish and Subscribe permissions down to the person, device or channel
  • Security – Secure all communications with enterprise-grade encryption standards
  • Analytics – Leverage visualizations into your realtime data streams
  • Data Sync – Sync application state across clients in realtime
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List of MIME Types

What is MIME type?

MIME stands for “Multipurpose Internet Mail Extensions“. It’s a way of identifying files on the Internet according to their nature and format. For example, using the “Content-type” header value defined in a HTTP response, the browser can open the file with the proper extension/plugin.

What does a MIME type look like?

A MIME type is a string identifier composed of two parts: a “type” and a “subtype”. The “type” refers to a logical grouping of many MIME types that are closely related to each other; it’s no more than a high level category. “subtypes” are specific to one file type within the “type”.

For example, the MIME value “application/xml” is used for XML documents and specifies that the “xml” subtype belongs in the “application” type.

MIME Types

Why are some MIME subtypes prefixed with “x-“?

The “x-” prefix of a MIME subtype simply means that it’s non-standard, i.e. not registered with the “Internet Assigned Numbers Authority” (IANA).

Why are some MIME subtypes prefixed with “vnd”?

The “vnd” prefix means that the MIME value is vendor specific.

Complete list of MIME Types

Suffixes applicable Media type and subtype(s)
.3dm x-world/x-3dmf
.3dmf x-world/x-3dmf
.a application/octet-stream
.aab application/x-authorware-bin
.aam application/x-authorware-map
.aas application/x-authorware-seg
.abc text/vnd.abc
.acgi text/html
.afl video/animaflex
.ai application/postscript
.aif audio/aiff
.aif audio/x-aiff
.aifc audio/aiff
.aifc audio/x-aiff
.aiff audio/aiff
.aiff audio/x-aiff
.aim application/x-aim
.aip text/x-audiosoft-intra
.ani application/x-navi-animation
.aos application/x-nokia-9000-communicator-add-on-software
.aps application/mime
.arc application/octet-stream
.arj application/arj
.arj application/octet-stream
.art image/x-jg
.asf video/x-ms-asf
.asm text/x-asm
.asp text/asp
.asx application/x-mplayer2
.asx video/x-ms-asf
.asx video/x-ms-asf-plugin
.au audio/basic
.au audio/x-au
.avi application/x-troff-msvideo
.avi video/avi
.avi video/msvideo
.avi video/x-msvideo
.avs video/avs-video
.bcpio application/x-bcpio
.bin application/mac-binary
.bin application/macbinary
.bin application/octet-stream
.bin application/x-binary
.bin application/x-macbinary
.bm image/bmp
.bmp image/bmp
.bmp image/x-windows-bmp
.boo application/book
.book application/book
.boz application/x-bzip2
.bsh application/x-bsh
.bz application/x-bzip
.bz2 application/x-bzip2
.c text/plain
.c text/x-c
.c++ text/plain
.cat application/vnd.ms-pki.seccat
.cc text/plain
.cc text/x-c
.ccad application/clariscad
.cco application/x-cocoa
.cdf application/cdf
.cdf application/x-cdf
.cdf application/x-netcdf
.cer application/pkix-cert
.cer application/x-x509-ca-cert
.cha application/x-chat
.chat application/x-chat
.class application/java
.class application/java-byte-code
.class application/x-java-class
.com application/octet-stream
.com text/plain
.conf text/plain
.cpio application/x-cpio
.cpp text/x-c
.cpt application/mac-compactpro
.cpt application/x-compactpro
.cpt application/x-cpt
.crl application/pkcs-crl
.crl application/pkix-crl
.crt application/pkix-cert
.crt application/x-x509-ca-cert
.crt application/x-x509-user-cert
.csh application/x-csh
.csh text/x-script.csh
.css application/x-pointplus
.css text/css
.cxx text/plain
.dcr application/x-director
.deepv application/x-deepv
.def text/plain
.der application/x-x509-ca-cert
.dif video/x-dv
.dir application/x-director
.dl video/dl
.dl video/x-dl
.doc application/msword
.dot application/msword
.dp application/commonground
.drw application/drafting
.dump application/octet-stream
.dv video/x-dv
.dvi application/x-dvi
.dwf drawing/x-dwf (old)
.dwf model/vnd.dwf
.dwg application/acad
.dwg image/vnd.dwg
.dwg image/x-dwg
.dxf application/dxf
.dxf image/vnd.dwg
.dxf image/x-dwg
.dxr application/x-director
.el text/x-script.elisp
.elc application/x-bytecode.elisp (compiled elisp)
.elc application/x-elc
.env application/x-envoy
.eps application/postscript
.es application/x-esrehber
.etx text/x-setext
.evy application/envoy
.evy application/x-envoy
.exe application/octet-stream
.f text/plain
.f text/x-fortran
.f77 text/x-fortran
.f90 text/plain
.f90 text/x-fortran
.fdf application/vnd.fdf
.fif application/fractals
.fif image/fif
.fli video/fli
.fli video/x-fli
.flo image/florian
.flx text/vnd.fmi.flexstor
.fmf video/x-atomic3d-feature
.for text/plain
.for text/x-fortran
.fpx image/vnd.fpx
.fpx image/vnd.net-fpx
.frl application/freeloader
.funk audio/make
.g text/plain
.g3 image/g3fax
.gif image/gif
.gl video/gl
.gl video/x-gl
.gsd audio/x-gsm
.gsm audio/x-gsm
.gsp application/x-gsp
.gss application/x-gss
.gtar application/x-gtar
.gz application/x-compressed
.gz application/x-gzip
.gzip application/x-gzip
.gzip multipart/x-gzip
.h text/plain
.h text/x-h
.hdf application/x-hdf
.help application/x-helpfile
.hgl application/vnd.hp-hpgl
.hh text/plain
.hh text/x-h
.hlb text/x-script
.hlp application/hlp
.hlp application/x-helpfile
.hlp application/x-winhelp
.hpg application/vnd.hp-hpgl
.hpgl application/vnd.hp-hpgl
.hqx application/binhex
.hqx application/binhex4
.hqx application/mac-binhex
.hqx application/mac-binhex40
.hqx application/x-binhex40
.hqx application/x-mac-binhex40
.hta application/hta
.htc text/x-component
.htm text/html
.html text/html
.htmls text/html
.htt text/webviewhtml
.htx text/html
.ice x-conference/x-cooltalk
.ico image/x-icon
.idc text/plain
.ief image/ief
.iefs image/ief
.iges application/iges
.iges model/iges
.igs application/iges
.igs model/iges
.ima application/x-ima
.imap application/x-httpd-imap
.inf application/inf
.ins application/x-internett-signup
.ip application/x-ip2
.isu video/x-isvideo
.it audio/it
.iv application/x-inventor
.ivr i-world/i-vrml
.ivy application/x-livescreen
.jam audio/x-jam
.jav text/plain
.jav text/x-java-source
.java text/plain
.java text/x-java-source
.jcm application/x-java-commerce
.jfif image/jpeg
.jfif image/pjpeg
.jfif-tbnl image/jpeg
.jpe image/jpeg
.jpe image/pjpeg
.jpeg image/jpeg
.jpeg image/pjpeg
.jpg image/jpeg
.jpg image/pjpeg
.jps image/x-jps
.js application/x-javascript
.js application/javascript
.js application/ecmascript
.js text/javascript
.js text/ecmascript
.jut image/jutvision
.kar audio/midi
.kar music/x-karaoke
.ksh application/x-ksh
.ksh text/x-script.ksh
.la audio/nspaudio
.la audio/x-nspaudio
.lam audio/x-liveaudio
.latex application/x-latex
.lha application/lha
.lha application/octet-stream
.lha application/x-lha
.lhx application/octet-stream
.list text/plain
.lma audio/nspaudio
.lma audio/x-nspaudio
.log text/plain
.lsp application/x-lisp
.lsp text/x-script.lisp
.lst text/plain
.lsx text/x-la-asf
.ltx application/x-latex
.lzh application/octet-stream
.lzh application/x-lzh
.lzx application/lzx
.lzx application/octet-stream
.lzx application/x-lzx
.m text/plain
.m text/x-m
.m1v video/mpeg
.m2a audio/mpeg
.m2v video/mpeg
.m3u audio/x-mpequrl
.man application/x-troff-man
.map application/x-navimap
.mar text/plain
.mbd application/mbedlet
.mc$ application/x-magic-cap-package-1.0
.mcd application/mcad
.mcd application/x-mathcad
.mcf image/vasa
.mcf text/mcf
.mcp application/netmc
.me application/x-troff-me
.mht message/rfc822
.mhtml message/rfc822
.mid application/x-midi
.mid audio/midi
.mid audio/x-mid
.mid audio/x-midi
.mid music/crescendo
.mid x-music/x-midi
.midi application/x-midi
.midi audio/midi
.midi audio/x-mid
.midi audio/x-midi
.midi music/crescendo
.midi x-music/x-midi
.mif application/x-frame
.mif application/x-mif
.mime message/rfc822
.mime www/mime
.mjf audio/x-vnd.audioexplosion.mjuicemediafile
.mjpg video/x-motion-jpeg
.mm application/base64
.mm application/x-meme
.mme application/base64
.mod audio/mod
.mod audio/x-mod
.moov video/quicktime
.mov video/quicktime
.movie video/x-sgi-movie
.mp2 audio/mpeg
.mp2 audio/x-mpeg
.mp2 video/mpeg
.mp2 video/x-mpeg
.mp2 video/x-mpeq2a
.mp3 audio/mpeg3
.mp3 audio/x-mpeg-3
.mp3 video/mpeg
.mp3 video/x-mpeg
.mpa audio/mpeg
.mpa video/mpeg
.mpc application/x-project
.mpe video/mpeg
.mpeg video/mpeg
.mpg audio/mpeg
.mpg video/mpeg
.mpga audio/mpeg
.mpp application/vnd.ms-project
.mpt application/x-project
.mpv application/x-project
.mpx application/x-project
.mrc application/marc
.ms application/x-troff-ms
.mv video/x-sgi-movie
.my audio/make
.mzz application/x-vnd.audioexplosion.mzz
.nap image/naplps
.naplps image/naplps
.nc application/x-netcdf
.ncm application/vnd.nokia.configuration-message
.nif image/x-niff
.niff image/x-niff
.nix application/x-mix-transfer
.nsc application/x-conference
.nvd application/x-navidoc
.o application/octet-stream
.oda application/oda
.omc application/x-omc
.omcd application/x-omcdatamaker
.omcr application/x-omcregerator
.p text/x-pascal
.p10 application/pkcs10
.p10 application/x-pkcs10
.p12 application/pkcs-12
.p12 application/x-pkcs12
.p7a application/x-pkcs7-signature
.p7c application/pkcs7-mime
.p7c application/x-pkcs7-mime
.p7m application/pkcs7-mime
.p7m application/x-pkcs7-mime
.p7r application/x-pkcs7-certreqresp
.p7s application/pkcs7-signature
.part application/pro_eng
.pas text/pascal
.pbm image/x-portable-bitmap
.pcl application/vnd.hp-pcl
.pcl application/x-pcl
.pct image/x-pict
.pcx image/x-pcx
.pdb chemical/x-pdb
.pdf application/pdf
.pfunk audio/make
.pfunk audio/make.my.funk
.pgm image/x-portable-graymap
.pgm image/x-portable-greymap
.pic image/pict
.pict image/pict
.pkg application/x-newton-compatible-pkg
.pko application/vnd.ms-pki.pko
.pl text/plain
.pl text/x-script.perl
.plx application/x-pixclscript
.pm image/x-xpixmap
.pm text/x-script.perl-module
.pm4 application/x-pagemaker
.pm5 application/x-pagemaker
.png image/png
.pnm application/x-portable-anymap
.pnm image/x-portable-anymap
.pot application/mspowerpoint
.pot application/vnd.ms-powerpoint
.pov model/x-pov
.ppa application/vnd.ms-powerpoint
.ppm image/x-portable-pixmap
.pps application/mspowerpoint
.pps application/vnd.ms-powerpoint
.ppt application/mspowerpoint
.ppt application/powerpoint
.ppt application/vnd.ms-powerpoint
.ppt application/x-mspowerpoint
.ppz application/mspowerpoint
.pre application/x-freelance
.prt application/pro_eng
.ps application/postscript
.psd application/octet-stream
.pvu paleovu/x-pv
.pwz application/vnd.ms-powerpoint
.py text/x-script.phyton
.pyc application/x-bytecode.python
.qcp audio/vnd.qcelp
.qd3 x-world/x-3dmf
.qd3d x-world/x-3dmf
.qif image/x-quicktime
.qt video/quicktime
.qtc video/x-qtc
.qti image/x-quicktime
.qtif image/x-quicktime
.ra audio/x-pn-realaudio
.ra audio/x-pn-realaudio-plugin
.ra audio/x-realaudio
.ram audio/x-pn-realaudio
.ras application/x-cmu-raster
.ras image/cmu-raster
.ras image/x-cmu-raster
.rast image/cmu-raster
.rexx text/x-script.rexx
.rf image/vnd.rn-realflash
.rgb image/x-rgb
.rm application/vnd.rn-realmedia
.rm audio/x-pn-realaudio
.rmi audio/mid
.rmm audio/x-pn-realaudio
.rmp audio/x-pn-realaudio
.rmp audio/x-pn-realaudio-plugin
.rng application/ringing-tones
.rng application/vnd.nokia.ringing-tone
.rnx application/vnd.rn-realplayer
.roff application/x-troff
.rp image/vnd.rn-realpix
.rpm audio/x-pn-realaudio-plugin
.rt text/richtext
.rt text/vnd.rn-realtext
.rtf application/rtf
.rtf application/x-rtf
.rtf text/richtext
.rtx application/rtf
.rtx text/richtext
.rv video/vnd.rn-realvideo
.s text/x-asm
.s3m audio/s3m
.saveme application/octet-stream
.sbk application/x-tbook
.scm application/x-lotusscreencam
.scm text/x-script.guile
.scm text/x-script.scheme
.scm video/x-scm
.sdml text/plain
.sdp application/sdp
.sdp application/x-sdp
.sdr application/sounder
.sea application/sea
.sea application/x-sea
.set application/set
.sgm text/sgml
.sgm text/x-sgml
.sgml text/sgml
.sgml text/x-sgml
.sh application/x-bsh
.sh application/x-sh
.sh application/x-shar
.sh text/x-script.sh
.shar application/x-bsh
.shar application/x-shar
.shtml text/html
.shtml text/x-server-parsed-html
.sid audio/x-psid
.sit application/x-sit
.sit application/x-stuffit
.skd application/x-koan
.skm application/x-koan
.skp application/x-koan
.skt application/x-koan
.sl application/x-seelogo
.smi application/smil
.smil application/smil
.snd audio/basic
.snd audio/x-adpcm
.sol application/solids
.spc application/x-pkcs7-certificates
.spc text/x-speech
.spl application/futuresplash
.spr application/x-sprite
.sprite application/x-sprite
.src application/x-wais-source
.ssi text/x-server-parsed-html
.ssm application/streamingmedia
.sst application/vnd.ms-pki.certstore
.step application/step
.stl application/sla
.stl application/vnd.ms-pki.stl
.stl application/x-navistyle
.stp application/step
.sv4cpio application/x-sv4cpio
.sv4crc application/x-sv4crc
.svf image/vnd.dwg
.svf image/x-dwg
.svr application/x-world
.svr x-world/x-svr
.swf application/x-shockwave-flash
.t application/x-troff
.talk text/x-speech
.tar application/x-tar
.tbk application/toolbook
.tbk application/x-tbook
.tcl application/x-tcl
.tcl text/x-script.tcl
.tcsh text/x-script.tcsh
.tex application/x-tex
.texi application/x-texinfo
.texinfo application/x-texinfo
.text application/plain
.text text/plain
.tgz application/gnutar
.tgz application/x-compressed
.tif image/tiff
.tif image/x-tiff
.tiff image/tiff
.tiff image/x-tiff
.tr application/x-troff
.tsi audio/tsp-audio
.tsp application/dsptype
.tsp audio/tsplayer
.tsv text/tab-separated-values
.turbot image/florian
.txt text/plain
.uil text/x-uil
.uni text/uri-list
.unis text/uri-list
.unv application/i-deas
.uri text/uri-list
.uris text/uri-list
.ustar application/x-ustar
.ustar multipart/x-ustar
.uu application/octet-stream
.uu text/x-uuencode
.uue text/x-uuencode
.vcd application/x-cdlink
.vcs text/x-vcalendar
.vda application/vda
.vdo video/vdo
.vew application/groupwise
.viv video/vivo
.viv video/vnd.vivo
.vivo video/vivo
.vivo video/vnd.vivo
.vmd application/vocaltec-media-desc
.vmf application/vocaltec-media-file
.voc audio/voc
.voc audio/x-voc
.vos video/vosaic
.vox audio/voxware
.vqe audio/x-twinvq-plugin
.vqf audio/x-twinvq
.vql audio/x-twinvq-plugin
.vrml application/x-vrml
.vrml model/vrml
.vrml x-world/x-vrml
.vrt x-world/x-vrt
.vsd application/x-visio
.vst application/x-visio
.vsw application/x-visio
.w60 application/wordperfect6.0
.w61 application/wordperfect6.1
.w6w application/msword
.wav audio/wav
.wav audio/x-wav
.wb1 application/x-qpro
.wbmp image/vnd.wap.wbmp
.web application/vnd.xara
.wiz application/msword
.wk1 application/x-123
.wmf windows/metafile
.wml text/vnd.wap.wml
.wmlc application/vnd.wap.wmlc
.wmls text/vnd.wap.wmlscript
.wmlsc application/vnd.wap.wmlscriptc
.word application/msword
.wp application/wordperfect
.wp5 application/wordperfect
.wp5 application/wordperfect6.0
.wp6 application/wordperfect
.wpd application/wordperfect
.wpd application/x-wpwin
.wq1 application/x-lotus
.wri application/mswrite
.wri application/x-wri
.wrl application/x-world
.wrl model/vrml
.wrl x-world/x-vrml
.wrz model/vrml
.wrz x-world/x-vrml
.wsc text/scriplet
.wsrc application/x-wais-source
.wtk application/x-wintalk
.xbm image/x-xbitmap
.xbm image/x-xbm
.xbm image/xbm
.xdr video/x-amt-demorun
.xgz xgl/drawing
.xif image/vnd.xiff
.xl application/excel
.xla application/excel
.xla application/x-excel
.xla application/x-msexcel
.xlb application/excel
.xlb application/vnd.ms-excel
.xlb application/x-excel
.xlc application/excel
.xlc application/vnd.ms-excel
.xlc application/x-excel
.xld application/excel
.xld application/x-excel
.xlk application/excel
.xlk application/x-excel
.xll application/excel
.xll application/vnd.ms-excel
.xll application/x-excel
.xlm application/excel
.xlm application/vnd.ms-excel
.xlm application/x-excel
.xls application/excel
.xls application/vnd.ms-excel
.xls application/x-excel
.xls application/x-msexcel
.xlt application/excel
.xlt application/x-excel
.xlv application/excel
.xlv application/x-excel
.xlw application/excel
.xlw application/vnd.ms-excel
.xlw application/x-excel
.xlw application/x-msexcel
.xm audio/xm
.xml application/xml
.xml text/xml
.xmz xgl/movie
.xpix application/x-vnd.ls-xpix
.xpm image/x-xpixmap
.xpm image/xpm
.x-png image/png
.xsr video/x-amt-showrun
.xwd image/x-xwd
.xwd image/x-xwindowdump
.xyz chemical/x-pdb
.z application/x-compress
.z application/x-compressed
.zip application/x-compressed
.zip application/x-zip-compressed
.zip application/zip
.zip multipart/x-zip
.zoo application/octet-stream
.zsh text/x-script.zsh
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