Things App Engine doesn ' t do ... Yet

When people use app engine for the first time, they ask what app engine won't do. Some of these things will happen in the near future, and some violate the nature of App engine design, it will not be added (to App Engine). It is difficult to list these features in a book because, over time, you may have been able to read them by Google. ( It is true that this list has become quite short from the first edition of this book.) <1.indeed,this list have gotten substantially shorter since the first editionof this book.>) but it's valuable to note these features here, especially Pay attention to alternative technologies.

An app can accept mail and XMPP on multiple addresses. None of these addresses can use a custom domain name until the book is written. See chapters 14th, 15 for more information about email and XMPP addresses.

An app can use Google Apps to accept network requests on a custom domain. Google Apps Associates a subdomain of your custom domain to an app, and if you choose, the subdomain can be www (http://www.example.com/). For this domain and all subdomains (http:// foo.www.example.com) will be routed to your app. Google apps also does not support requests for "bare" domains, such as http://example.com/.

App Engine does not support streaming media and long-term connections to your application's servers. Applications can use the channel service to push information to the browser in real time. In some cases XMPP using XMPP service is also a notification option (such as Google Talk). These mechanisms are better than polling techniques, and the client periodically asks for the latest changes to the application. <2.these mechanisms is preferred to a polling technique,where the client asks the application for updates on a regular Basis.> polling is difficult to scale (5,000 analog users poll one per 5 seconds = 1000 polls per second) and are not suitable for all applications. Also note that the request processor is not able to communicate with the client while processing other computations. The server only sends a response to the client request after the processor (handler) returns control to the server.

APP engine only supports network requests through HTTP, HTTPs, mail, and XMPP messages using the service. It does not support other network connections. For example, a client cannot connect to an App Engine app via FTP.

APP engine Datastore does not support full-text search queries, such as implementing a search engine for a text management decency. The search service, as of the completion of this book or beta test, provides a powerful document-based, datastore-integrated search feature. But full-text search is not an inherent capability of the Datastore query engine.

Things App Engine doesn ' t do ... Yet