Qt and Web Services

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Qt and Web Services

This page tracks current Web Service trends and the requirements of those in Qt. See also the "corresponding task in the Qt bug tracker":http://bugreports.qt.nokia.com/browse/QTBUG-13353 .

Areas for Improvement

• "OAuth":http://bugreports.qt.nokia.com/browse/QTBUG-6229 . Needed for logging in to e.g. Twitter, Facebook, Foursquare etc.

OAuth comes in two versions:

• • OAuth 1.0a: Authentication / authorization is done in either HTTP headers or URL, no SSL needed, but quite some signing / nonce creating etc. logic. There are two major 3rd party implementations:
    • QOAuth: depends on QCA and QCA's OpenSSL plugin and spins its own event loop to fake synchronous requests (which is bad).
    • kOAuth: I have not looked at that closely.
  • OAuth 2: No signing / hashing etc. required, expects data to be sent over SSL. As far as I can see this can be easily supported on top of Qt.

It seems like OAuth 2 is really taking over (Facebook, Foursquare, Google Data APIs offer it already); sites using OAuth 1.0a: (Twitter, LinkedIn).

• "JSON support":http://bugreports.qt.nokia.com/browse/QTBUG-12761 . Web Services usually offer their data in either XML or JSON, with JSON having become a lot more popular than XML. JSON can be parsed directly from QML (I think - could somebody confirm?), if parsing within C++ is used, there is a 3rdparty solution called "QJson":http://qjson.sourceforge.net/ and one written by Girish called "qjsonparser":http://blog.forwardbias.in/2011/01/qjsonparser-parse-and-stringify-json-with-qt.html

Completed features

• HTTP DELETE (done for 4.6). Can be used for some web services; however not a hard requirement, usually services allow to fake it or use it via POST.
• "HTTP multipart messages":http://bugreports.qt.nokia.com/browse/QTBUG-6222 (done for 4.8). Needed for Flickr / Facebook etc. image upload; in general used very often where uploading binary data is involved.

Web Services Matrix

| Name | Access Method | Data format | Authentication | Additional Requirements | Comment | | Facebook | REST, FQL (Facebook Query Language, their own SQL - style language) | XML, JSON | OAuth 2.0 for desktop apps | HTTP multipart messages (for uploading photos) | offers a XML schema at http://api.facebook.com/1.0/facebook.xsd code generation possible, cool! for developing Facebook applications, there is: FBML (their own HTML - style language), XFBML (for using FBML in a normal HTML site), FBJS (their own JavaScript-style language)
there is already a Qt Facebook API called Fantasma at http://wiki.developers.facebook.com/index.php/User:C++ (seems to be quite old, uses QHttp) | | Flickr | REST, SOAP, XML - RPC | XML (SOAP 1.2 / plain / XML - RPC), JSON, PHP - serialized | as with facebook, some md5 required and launching a browser window for authorization (similar to OAuth) | HTTP multipart messages (for uploading photos) | | | Twitter | REST, ATOM (for some methods) | XML (plain / ATOM), JSON | OAuth (login via web page); HTTP Basic Auth (only until June 2010) | OAuth 1.0a | some parts of the API are only available in JSON and ATOM, namely search and trends
Authentication described at http://apiwiki.twitter.com/Sign-in-with-Twitter | | MySpace | REST | XML, JSON | OAuth | OAuth | the API supports OpenSocial API, which is "a common API for social applications" | | Google Maps | JavaScript | | | | no real Web service API, but a JavaScript library to be used within a browser | | Google Search | Ajax, REST | JavaScript (Ajax), JSON (REST) | none required | | REST interface is very limited, see http://googlesystem.blogspot.com/2008/04/google-search-rest-api.html
REST API documented at http://code.google.com/apis/ajaxsearch/documentation/#fonje | | Bing Search | REST, SOAP+WSDL | XML (plain / SOAP) | none required | | | | Last.fm | REST, XML - RPC, some calls as well RSS and iCal | XML (plain / XML-RPC) | either Web browser (Web / Desktop apps) or getting username & password from user and send that via md5 to last.fm | | there is a Qt C++ API called Liblastfm: http://github.com/mxcl/liblastfm/tree/master | | Google Data API | REST (using Atom Publishing Protocol) | XML (Atom), JSON, RSS | for installed apps: their own ClientLogin (via HTTPS, but then sending the 2-year-expiry auth key in plaintext!), for web apps: either an AuthSub mechanism (directing the user to a google web page) or OAuth | HTTP multipart messages (not a strict requirement, for uploading photos etc.), OAuth | | | Amazon Cloud Services (EC2, S3 etc.) | SOAP+WSDL, REST | XML | SOAP: WS-Security (http://docs.amazonwebservices.com/AWSEC2/2009-08-15/DeveloperGuide/index.html?using-soap-api.html#using-soap-api-authentication), REST: own security scheme based on SHA1/SHA256 (http://docs.amazonwebservices.com/AWSEC2/2009-08-15/DeveloperGuide/index.html?using-query-api.html#query-authentication , I saw no password there, strangely) | SOAP: WS-Security | | | Ebay API | SOAP+WSDL, REST, HTTP GET | XML, JSON | | HTTP multipart messages | | | Wordpress | XMLRPC | XML | | | | | StudiVZ (German Facebook clone) | REST | XML, JSON, JavaScript, ATOM+XML | OAuth | OAuth | supports OpenSocial ; currently says "OAuth not supported at the moment", I don't know if they are actually using it or not | | LinkedIn | REST | XML | OAuth 1.0a | OAuth 1.0a | | | Windows Messenger Connect | JavaScript | | | OAuth WRAP | | |