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<i>What is a "discovery service?"</i>
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Generally speaking, a <i>discovery service</i> is a solution to the <a href=https://spaces.at.internet2.edu/display/SHIB2/IdPDiscovery id=xpcs title="identity provider discovery">identity provider discovery</a> problem, a longstanding issue in the federated identity management space. As the term is used here, a <i>discovery service</i> provides a browser-based interface where a user selects his or her home organization (i.e., identity provider). A service provider uses this information to initiate SAML Web Browser SSO.<br>
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The phrase "Where Are You From?" (WAYF) is often used to characterize IdP discovery. Historically, the term "WAYF" has referred to both software and protocol. The WAYF software has all but been eliminated by newer discovery service implementations (such as this one), but the WAYF protocol lives on, mainly for backwards compatibility with SAML V1.1.<br>
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In addition to the WAYF protocol, a discovery service implements the <i><a href=http://wiki.oasis-open.org/security/IdpDiscoSvcProtonProfile id=zw84 title="SAML V2.0 Identity Provider Discovery Protocol">SAML V2.0 Identity Provider Discovery Protocol</a></i>. This protocol differs from the WAYF protocol in one very important respect. Whereas the WAYF protocol forwards an authentication request directly to the identity provider, the <i>Identity Provider Discovery Protocol</i> returns control to the service provider, which provides increased flexibility, privacy and security.<br>
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To learn how a discovery service works, the SWITCH federation has an <a href=http://www.switch.ch/aai/demo/ id=a_-o title="excellent series of demos">excellent series of demos</a> that illustrate how a discovery service integrates into a typical SAML flow.
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<i>What is the InCommon Discovery Service?</i>
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The <i>InCommon Discovery Service</i> is a deployment of the <i><a href=https://forge.switch.ch/redmine/projects/wayf id=n3cb title=SWITCHwayf>SWITCHwayf</a></i> software implementation, a <a href=http://www.switch.ch/aai/support/tools/wayf.html id=yaf: title="software project">software project</a> of the SWITCH federation.<br>
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<b>IMPORTANT!</b> The InCommon Discovery Service is a <b>pre-production test deployment</b> of the SWITCHwayf software implementation.<br>
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The InCommon Discovery Service will eventually replace the InCommon WAYF (Where Are You From?) with a Federation-wide discovery service that supports the <i><a href=http://wiki.oasis-open.org/security/IdpDiscoSvcProtonProfile id=f8p9 title="SAML V2.0 Identity Provider Discovery Protocol and Profile">SAML V2.0 Identity Provider Discovery Protocol and Profile</a></i>. To ease the transition from the WAYF, the InCommon Discovery Service is backwards compatible with the InCommon WAYF.
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<i>Why is InCommon replacing the WAYF with the Discovery Service?</i>
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The current InCommon WAYF is not compatible with SAML V2.0 or Shibboleth 2.x. As Shibboleth 1.x is no longer supported by the Shibboleth Project, more organizations will be moving to Shibboleth 2.x. In addition, the production version of the InCommon Discovery Service will leverage metadata, providing additional flexibility, privacy and security that the InCommon WAYF does not provide.
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<i>Why is the InCommon Discovery Service a pre-production service at this time?</i>
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The user interface of the pre-production InCommon Discovery Service is experimental. The production service will incorporate the feedback received from the community during the pre-production phase.<br>
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The pre-production InCommon Discovery Service does not currently take advantage of Federation metadata. The production service will leverage Federation metadata to increase the flexibility, privacy and security of the deployment.<br>
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There is no standby InCommon Discovery Service to fail over in case of an outage.<br>
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<i>What does the InCommon Discovery Service look like?</i>
<br><br>Here's a recent screen shot of the InCommon Discovery Service:
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<img src="/download/attachments/17105174/dm8mb2j_1f7bntqcq_b.jpg">
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<i>Which SAML Service Provider implementations support the InCommon Discovery Service?</i>
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The InCommon Discovery Service works with <b>all</b> supported versions of the Shibboleth Service Provider software. To use the native <i>SAML V2.0 Identity Provider Discovery Protocol</i>, Shibboleth SP version 2.0 (or later) is required.<br>
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The InCommon Discovery Service also works with simpleSAMLphp version 1.1 or later, but this has not been tested.<br>
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There may be other SP implementations that support the InCommon Discovery Service. If you find one that does, please share your experiences with us (discovery@incommon.org).<br>
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<i>If my SAML Service Provider implementation supports an "embedded discovery service," do I still need to be concerned about the InCommon Discovery Service?</i>
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The InCommon Discovery Service is a centralized discovery service for general use within the InCommon Federation. For those service providers that provide their own discovery service, through an embedded service or some other centralized service, the InCommon Discovery Service may not be applicable. How you handle discovery in conjunction with particular federated services at your institution is completely up to you.<br>
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That said, it is well known that embedded discovery provides the best overall experience for users, so you should by all means consider that as an alternative to centralized services such as the InCommon Discovery Service.<br>
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<i>What do I need to do?</i>
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First and foremost, try it out and give us your feedback (discovery@incommon.org).<br>
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<b>All</b> Service Provider deployments should reconfigure their software to point at the InCommon Discovery Service instead of the InCommon WAYF. The latter will be phased out and eventually retired.<br>
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Consult the Shibboleth documentation for instructions how to configure a Shibboleth 2.x SP <a href=https://spaces.at.internet2.edu/display/SHIB2/NativeSPSessionInitiator id=c0k2 title=SessionInitiator>SessionInitiator</a> with one or more discovery handlers. Once you've configured (and tested) your Shibboleth 2.x SP to use the InCommon Discovery Service, update your InCommon Federation metadata to include the <font face="courier new"><DiscoveryResponse></font> endpoints that will be required to access the production service.<br>
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<i>Where can I try out the new InCommon Discovery Service?</i>
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Just visit this test page: <a href=https://service1.internet2.edu/test/ id=o_xe title=https://service1.internet2.edu/test/>https://service1.internet2.edu/test/</a><br>
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<i>How do I configure a Shibboleth 1.x SP to use the InCommon Discovery Service instead of the InCommon WAYF?</i>
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<b>Note:</b> As of June 30, 2010, Shibboleth 1.x is no longer supported by the Shibboleth Project, so you should upgrade your software as soon as possible.<br>
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A Shibboleth 1.x SP cannot take advantage of all the features of the new InCommon Discovery Service, so we recommend you upgrade your Shibboleth SP deployment as soon as you can. In the meantime, you can (and should) reconfigure your Shibboleth 1.x SP to use the InCommon Discovery Service instead of the InCommon WAYF. The latter will be phased out and eventually retired.<br>
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If you're already using the InCommon WAYF, you will find something like this in your <a href=https://spaces.at.internet2.edu/display/SHIB/SessionInitiator id=r20z title="SP 1.x configuration">SP 1.x configuration</a> file (shibboleth.xml):<br>
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<font face="courier new"><SessionInitiator id="wayf" Location="/WAYF/InCommon"</font><br style="FONT-FAMILY:Courier New">
<font face="courier new"> Binding="urn:mace:shibboleth:sp:1.3:SessionInit"</font><br style="FONT-FAMILY:Courier New">
<font face="courier new"> wayfURL="https://wayf.incommonfederation.org/InCommon/WAYF"</font><br style="FONT-FAMILY:Courier New">
<font face="courier new"> wayfBinding="urn:mace:shibboleth:1.0:profiles:AuthnRequest" /></font><br style="FONT-FAMILY:Courier New">
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To point your SP at the new Discovery Service endpoint, make the following configuration change:<br>
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<SessionInitiator id="wayf" Location="/WAYF/InCommon"<br>
Binding="urn:mace:shibboleth:sp:1.3:SessionInit"<br>
wayfURL="<b>https://wayf.incommonfederation.org/DS</b>"<br>
wayfBinding="urn:mace:shibboleth:1.0:profiles:AuthnRequest" /><br>
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Since the InCommon Discovery Service is backwards compatible with the InCommon WAYF, the above configuration should work exactly the same as before.<br>
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<i>How do I configure a Shibboleth 2.x SP to use the InCommon Discovery Service instead of the InCommon WAYF?</i>
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In the very least, you should reconfigure your Shibboleth 2.x SP to use the InCommon Discovery Service instead of the InCommon WAYF. The latter will be phased out and eventually retired.<br>
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If you're already using the InCommon WAYF, you will find something like this in your <a href=https://spaces.at.internet2.edu/display/SHIB2/NativeSPShibbolethXML id=f_-. title="SP 2.x configuration">SP 2.x configuration</a> file (shibboleth2.xml):<br>
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<SessionInitiator type="WAYF" URL="https://wayf.incommonfederation.org/InCommon/WAYF" /><br>
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To point your SP at the new Discovery Service endpoint, make the following configuration change:<br>
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<SessionInitiator type="WAYF" URL="<b>https://wayf.incommonfederation.org/DS</b>" /><br>
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Since the InCommon Discovery Service is backwards compatible with the InCommon WAYF, the above configuration should work exactly the same as before.<br>
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<i>How do I configure a Shibboleth 2.x SP to use the InCommon Discovery Service with the SAML V2.0 Identity Provider Discovery Protocol?</i>
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<b>Note:</b> The InCommon Discovery Service is a pre-production test deployment, so we recommend you return your SP configuration to its original state after trying the sample configuration below.<br>
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To use the InCommon Discovery Service with the <i>SAML V2.0 Identity Provider Discovery Protocol</i>, modify your <a href=https://spaces.at.internet2.edu/display/SHIB2/NativeSPShibbolethXML id=kwkk title="SP 2.x configuration">SP 2.x configuration</a> file (shibboleth2.xml) something like the following:<br>
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<SessionInitiator type="Chaining" Location="/DS" id="DS" isDefault="true" relayState="cookie"><br>
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<SessionInitiator type="SAML2"<br>
defaultACSIndex="1" <b>acsByIndex="false"</b> template="bindingTemplate.html" /><br>
<SessionInitiator type="Shib1" defaultACSIndex="5" /><br>
<SessionInitiator type="<b>SAMLDS</b>" URL="<b>https://wayf.incommonfederation.org/DS</b>" /><br>
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</SessionInitiator><br>
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Normally, the above configuration change would be followed by a change to SP metadata, but since the pre-production test version of the InCommon Discovery Service does not use metadata, that step can be skipped for now. We recommend, however, that you <b>update your Federation metadata now</b>, as suggested in the following FAQ. Then, when the production version of the InCommon Discovery Service is released, you'll be ready to go.<br>
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<i>How do I update Federation metadata to leverage the InCommon Discovery Service?</i>
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<b>Note:</b> The pre-production test deployment of the InCommon Discovery Service does not require SP metadata, but the production service will, so now is a good time to update your metadata.<br>
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Using the <font face="courier new"><SessionInitiator></font> in the previous FAQ, the location of the return endpoint (i.e., the endpoint location at the SP that the DS returns the user to, once the user's preferred IdP has been chosen) is:<br>
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<font face="courier new">https://</font><i style="FONT-FAMILY:Courier New">host</i><font face="courier new">/Shibboleth.sso/DS</font><br>
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where <i style="FONT-FAMILY:Courier New">host</i> is the hostname of your SP. Now simply login to the site admin web application, edit your SP's metadata, and add a <font face="courier new"><DiscoveryResponse></font> element with the above endpoint location.<br>
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For now, that's all that can be done. When the production version of the InCommon Discovery Service is finally released, you can modify the <font face="courier new"><SessionInitiator></font> as in the previous FAQ and test by requesting a protected resource at the SP.<br>
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If you have any problems, drop us a line at discovery@incommon.org.
For More Information
- SWITCH demos http://www.switch.ch/aai/demo/
- SAML V2.0 Identity Provider Discovery Protocol and Profile http://wiki.oasis-open.org/security/IdpDiscoSvcProtonProfile
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We have exciting news! An updated InCommon Federation wiki is now available. Please visit the new InCommon Federation Library for updated content. This wiki is preserved for historical records only. It will no longer be updated. We invite you to come check out the new Library. Don't forget to update your bookmarks accordingly.
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InCommon Discovery Service
The InCommon Discovery Service is a centralized IdP discovery interface for all InCommon participants. Visit our web site for a brief history of discovery or visit the Discovery Service FAQ for more information about the InCommon Discovery Service.
Software and Metadata Considerations
Configuring Metadata for Discovery
If your SP supports SAML V2.0, and the SP is configured to use the SAML V2.0 Identity Provider Discovery Protocol, you must configure your SP's metadata to include one or more <idpdisc:DiscoveryResponse> elements. If you don't, a request to a properly configured discovery service endpoint (such as the InCommon Discovery Service) will fail.
If you inspect InCommon metadata, you will find extension endpoints such as the following in SP metadata:
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<idpdisc:DiscoveryResponse index="1"
xmlns:idpdisc="urn:oasis:names:tc:SAML:profiles:SSO:idp-discovery-protocol"
Binding="urn:oasis:names:tc:SAML:profiles:SSO:idp-discovery-protocol"
Location="https://carmenwiki.osu.edu/Shibboleth.sso/Login"/>
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The namespace and binding attributes attached to the <idpdisc:DiscoveryResponse> element are defined in the SAML V2.0 Identity Provider Discovery Protocol and Profile specification. The endpoint location is the return address for the SP, that is, where the Discovery Service returns to once the user's preferred IdP has been determined.
Likewise if your SP is configured to issue SAML V2.0 authentication requests, you must add one or more SAML V2.0 <md:AsssertionConsumerService> endpoints to your metadata. (The same is true of SAML V1.1, by the way.) Failure to do so will result in errors when such requests are issued to IdPs, since your metadata will lack sufficient support for the desired protocol.
The Discovery Service and the IdP have similar requirements with respect to metadata. Both components will redirect the browser user back to the SP, but only to a trusted endpoint at the SP. Those endpoints must be called out in SP metadata, otherwise the protocol is violated and the redirect will not occur.
Configuring your SAML Service Provider Software
In general, configuring your SP software for discovery depends on the protocol(s) it supports. If your SP supports SAML V1.1 only, you must configure your SP to use the legacy WAYF protocol, which is based on the proprietary Shibboleth 1.x AuthnRequest protocol. If your SP supports SAML V2.0 only, you must configure your SP to use the SAML V2.0 Identity Provider Discovery Protocol. In that case, you must configure SP metadata as described in the previous section.
Of course, if your SP supports both SAML V1.1 and SAML V2.0, you have a choice, but clearly SAML V2.0 is preferred since it offers a much richer set of deployment options. Note that some SP implementations are sophisticated enough to make a runtime decison based on the supported protocols called out in IdP metadata.
Instructions how to configure the Shibboleth SP for discovery can be found elsewhere in this wiki.
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