"Anycast for Any Service"

OASIS

Overlay Anycast Service InfraStructure

Home
 •• Project home page
Overview
 •• Brief overview and news
Usage
 •• Using OASIS
Maps
 •• Current deployment
Services
 •• Current services
Lists
 •• Mailing Lists
Pubs
 •• Publications and people
Download
 •• Source code
This page describes how one can use OASIS via either DNS and HTTP. Its HTTP interface also exposes a variety of other functionality; the API is described below. The HTTP interface can respond with either HTML- or XML-formatted output; the latter is especially useful for integration into AJAX-powered web services.

DNS interface

To access OASIS vis a DNS interface, simply access <service>.nyuld.net. As an example, let's see what gets returned when trying to access service 'coralcdn' via DNS: 
   $ dig coralcdn.nyuld.net

   ; <<>> DiG 9.3.1 <<>> coralcdn.nyuld.net
   ;; global options:  printcmd
   ;; Got answer:
   ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 4660
   ;; flags: qr rd ra; QUERY: 1, ANSWER: 3, AUTHORITY: 1, ADDITIONAL: 0

   ;; QUESTION SECTION:
   ;coralcdn.nyuld.net.            IN      A

   ;; ANSWER SECTION:
   coralcdn.nyuld.net.     600     IN      CNAME   coralcdn.ab4203b5.oasis.nyuld.net.
   coralcdn.ab4203b5.oasis.nyuld.net. 60 IN A      171.66.3.181
   coralcdn.ab4203b5.oasis.nyuld.net. 60 IN A      171.66.3.182

   ;; AUTHORITY SECTION:
   coralcdn.ab4203b5.oasis.nyuld.net. 600 IN NS    171.66.3.181.ip4.oasis.nyuld.net.

   ;; Query time: 367 msec
   ;; SERVER: 127.0.0.1#53(127.0.0.1)
   ;; MSG SIZE  rcvd: 137

HTTP interface

Locate a particular IP address

   http://http.nyuld.net:8096/clnt.html?ip=<ip>
HTML response for lookup on an NYU server: 
   $ http://http.nyuld.net:8096/clnt.html?ip=216.165.108.10

   HTTP/1.0 200 OK
   Server: OasisHttpd/0.1.38 (See http://oasis.coralcdn.org/)
   Connection: close
   Content-Type: text/html; charset=iso-8859-1
   Content-Length: 240
   X-OASIS-Target: 216.165.108.10
   X-OASIS-Location: 40.729,-73.993,0.270

   <table border=0><tr><td><b><font color="blue">IP</font></b>
     <br>AS Num<br>Latitude<br>Longitude<br>Error (us)</td>
     <td>   </td>
     <td><b><font color="blue">216.165.108.10</font></b>
     <br>12<br>40729<br>-73993<br>270</td></tr>
   </table>
XML response: 
   $ http://http.nyuld.net:8096/clnt.xml?ip=216.165.108.10

   HTTP/1.0 200 OK
   Server: OasisHttpd/0.1.38 (See http://oasis.coralcdn.org/)
   Connection: close
   Content-Type: application/xml
   Content-Length: 113
   X-OASIS-Target: 216.165.108.10
   X-OASIS-Location: 40.729,-73.993,0.270

   <markers>
   <marker no="1" name="216.165.108.10" asn="12" lat="40.729" 
lng="-73.993" rtt="0.270"/>
   </markers>

Estimated distance between two IP addresses

   http://http.nyuld.net:8096/dist.html?src=<ip>&dst=<ip>
HTML response for distance between MIT and NYU: 
   $ http://http.nyuld.net:8096/dist.html?src=18.0.0.1&dst=216.165.108.10

   HTTP/1.0 200 OK
   Server: OasisHttpd/0.1.38 (See http://oasis.coralcdn.org/)
   Connection: close
   Content-Type: text/html; charset=iso-8859-1
   Content-Length: 261
   X-OASIS-Source: 42.363,-71.092,0.394
   X-OASIS-Destination: 40.729,-73.993,0.270
   X-OASIS-Kilometers: 370
   X-OASIS-Miles: 229
   X-OASIS-RTT-Est: 3

   <table>
     <tr><td>Source:</td><td>42.363,-71.092,0.394</td></tr>
     <tr><td>Destination:</td><td>40.729,-73.993,0.270</td></tr>
     <tr><td>Kilometers:</td><td>370</td></tr>
     <tr><td>Miles:</td><td>229</td></tr>
     <tr><td>Estimated RTT:</td><td>3</td></tr>
   </table>
XML response for distance between MIT and NYU: 
   $ http://http.nyuld.net:8096/dist.xml?src=18.0.0.1&dst=216.165.108.10

   HTTP/1.0 200 OK
   Server: OasisHttpd/0.1.38 (See http://oasis.coralcdn.org/)
   Connection: close
   Content-Type: text/html; charset=iso-8859-1
   Content-Length: 261
   X-OASIS-Source: 42.363,-71.092,0.394
   X-OASIS-Destination: 40.729,-73.993,0.270
   X-OASIS-Kilometers: 370
   X-OASIS-Miles: 229
   X-OASIS-RTT-Est: 3

   <markers>
   <marker no="1" srclat="42.363" srclng="-71.092" srcerr="0.394" 
dstlat="40.729" dstlng="-73.993" dsterr="0.270" km="370" miles="229" 
rttest="3"/>
   </markers>
Note that both kilometers/miles and RTT is just a rough estimate given the estimated geographic distance. They should not be used for predictive accuracy.

Anycast functionality for a specified service

   http://http.nyuld.net:8096/anycast.html?pol=<service>
      [&ip=<ip>][&lat=<latitude>][&lng=<longitude>][&max=<int>][&min=<int>]
This query returns a set of IP addresses at which the specified service is running. The following precedence of optional arguments is used: (1) If an <ip> is specified, servers nearby to <ip> are returned. Next, (2) if a latitude and longitude are supplied, servers nearby those coordinates are returned. Otherwise, (3) servers nearby to the requesting client's IP address are returned.

The optional <max> and <min> specify the desired number of values to return; otherwise, values from the service's default policy are used. We recommend a small <max> value (<= 3); otherwise, these requests can cause load balancing problems.

HTML response is just a CRLF-separated list of IP addresses: 

   $ http://http.nyuld.net:8096/anycast.html?pol=coralcdn&ip=216.165.108.10&max=3
   $ http://http.nyuld.net:8096/anycast.html?pol=coralcdn&lat=40.7&lng=-74&max=3

   HTTP/1.0 200 OK
   Server: OasisHttpd/0.1. (See http://oasis.coralcdn.org/)
   Connection: close
   Content-Type: text/html; charset=iso-8859-1
   Content-Length: 51

   216.165.109.181
   216.165.109.182
   216.165.109.179
XML response: 
   $ http://http.nyuld.net:8096/anycast.xml?pol=coralcdn

   HTTP/1.0 200 OK
   Server: OasisHttpd/0.1. (See http://oasis.coralcdn.org/)
   Connection: close
   Content-Type: text/html; charset=iso-8859-1
   Content-Length: 211

   <markers>
   <marker no="0" serv="coralcdn" addr="216.165.109.181"/>
   <marker no="1" serv="coralcdn" addr="216.165.109.182"/>
   <marker no="2" serv="coralcdn" addr="216.165.109.179"/>
   </markers>

Generate an HTTP redirect

   http://http.nyuld.net:8096/redir.html?pol=<service>[&ip=<ip>][&suffix=<sfx>]
Here, we just generate an HTTP redirect to a server belonging to the specified service. If an <ip> is specified, a server nearby to <ip> is returned; otherwise, the requesting client's IP address is used. The optional <sfx> is appended to the end of the location. HTML response to a redirect query near to NYU: 
   $  http://http.nyuld.net:8096/redir.html?pol=coralcdn&ip=216.165.108.10&suffix=foo.html

   HTTP/1.0 302 Found
   Server: OasisHttpd/0.1.38 (See http://oasis.coralcdn.org/)
   Connection: close
   Content-Type: text/html; charset=iso-8859-1
   Location: http://216.165.109.181/foo.html

   <html><head><title>302 Found</title></head><body>
   <h1>Redirect: 302 Found</h1><br>
   <a href="http://216.165.109.181/foo.html">
     http://216.165.109.181/foo.html</a>
   <br><br><hr>Server OasisHttpd/0.1.38 
     (See http://oasis.coralcdn.org/)</i>
   <br></body></html>

Determine policy information for service running on OASIS

   http://http.nyuld.net:8096/pol.html?pol=<service>
HTML format: 
   $ http://http.nyuld.net:8096/pol.html?pol=opendht

   HTTP/1.0 200 OK
   Server: OasisHttpd/0.1. (See http://oasis.coralcdn.org/)
   Connection: close
   Content-Type: text/html; charset=iso-8859-1

   <table border=0><tr>
   <td><b><font color="blue">Service</font></b>
   <br>Max records<br>Min records<br>Record TTLs</td>
   <td>   </td>
   <td><b><font color="blue">opendht</font></b><br>2<br>1<br>120 s</td>
   </tr></table>
XML format: 
   $ http://http.nyuld.net:8096/pol.xml?pol=opendht

   HTTP/1.0 200 OK
   Server: OasisHttpd/0.1. (See http://oasis.coralcdn.org/)
   Connection: close
   Content-Type: text/html; charset=iso-8859-1

   <policies>
   <policy serv="opendht" max="2" min="1" ttl="120"/>
   </policies>


NYU Secure Computer Systems / Project IRIS   ·   7th Floor · 715 Broadway · New York, NY 10003 · USA