Hi Niels,

I have a prototype of XWIki partially working with some changes on app 
engine

http://xwiki1.appspot.com/bin/view/Main/

I've made all the servlet / jvm part work as well as the cache subsystem.
The main missing piece is a real storage with support for querying.

We have no plans at this point to continue the work. If somebody wants 
to help I can give directions.

Ludovic

Niels Mayer a écrit :
> http://code.google.com/appengine/docs/whatisgoogleappengine.html
>
> Java is supported via Java 6 JVM and standard libs:
> http://code.google.com/appengine/docs/java/gettingstarted/
>
> My biggest question w/r/t Xwiki is AppEngine's database support:
>
>   
>> The Datastore
>>
>> App Engine provides a powerful distributed data storage service that
>> features a query engine and transactions. Just as the distributed web server
>> grows with your traffic, the distributed datastore grows with your data.
>>
>> The App Engine datastore is not like a traditional relational database.
>> Data objects, or "entities," have a kind and a set of properties. Queries
>> can retrieve entities of a given kind filtered and sorted by the values of
>> the properties. Property values can be of any of the supported property
>> value 
>> types<http://code.google.com/appengine/docs/python/datastore/typesandpropertyclasses.html>
>> .
>>
>> Datastore entities are "schemaless." The structure of data entities is
>> provided by and enforced by your application code. The Java JDO/JPA
>> interfaces and the Python datastore interface include features for applying
>> and enforcing structure within your app. Your app can also access the
>> datastore directly to apply as much or as little structure as it needs.
>>
>> The datastore is strongly 
>> consistent<http://en.wikipedia.org/wiki/Consistency_model>and uses optimistic
>> concurrency 
>> control<http://en.wikipedia.org/wiki/Optimistic_concurrency_control>.
>> An update of a entity occurs in a transaction that is retried a fixed number
>> of times if other processes are trying to update the same entity
>> simultaneously. Your application can execute multiple datastore operations
>> in a single transaction which either all succeed or all fail, ensuring the
>> integrity of your data.
>>
>> The datastore implements transactions across its distributed network using
>> "entity groups." A transaction manipulates entities within a single group.
>> Entities of the same group are stored together for efficient execution of
>> transactions. Your application can assign entities to groups when the
>> entities are created.
>>
>>     
> http://code.google.com/appengine/docs/java/gettingstarted/usingdatastore.html
>
>   
>> App Engine includes support for two different API standards for the
>> datastore: Java Data Objects <http://java.sun.com/jdo/index.jsp> (JDO) and
>> Java Persistence 
>> API<http://java.sun.com/developer/technicalArticles/J2EE/jpa/>(JPA). These 
>> interfaces are provided by DataNucleus
>> Access Platform <http://www.datanucleus.org/>, an open source
>> implementation of several Java persistence standards, with an adapter for
>> the App Engine datastore.
>>
>>     
> ..............
>
> Question:
>
> What would it take to make Xwiki work on Google App-engine? Is the
> "datastore" google provides compatible with xwiki's database needs?
>
> What other Java-hosting services "out there" support Xwiki? Database and
> java "hosting" issues for Xwiki can be problematic, even though it makes
> more sense, to public-host using a language like Java.
>
> I think for my own situation, I would end up "hosting" Xwiki myself, as a
> $500.00 box can run a few Xwiki-based sites just fine. However, for
> people/customers wanting an Xwiki-based site that don't know about system
> administration, JVM's, apache, etc, it would be nice if there was an easier
> path to managed hosting in an "open market." This needn't limit xwiki.com's
> hosting market, as much as it would open-up xwiki for wider deployment and
> use, and make it competitive in situations where Php or RoR might have
> easier buy-in, such as in the USA....
>
> Imagine if in the future, one of the installers Xwiki.org offered worked
> directly with http://appengine.google.com/ so that people would
> actually have their own live, public xwiki sites hosted for them. There's
> plenty of sites that would be happy with this level of free
> service ( http://code.google.com/appengine/docs/quotas.html ):
>
> Resource Free Default Quota Billing Enabled Quota  Daily Limit Maximum
> Rate Daily
> Limit Maximum Rate  Requests 1,300,000 requests 7,400 requests/minute
> 43,000,000
> requests 30,000 requests/minute  Outgoing Bandwidth
> (billable<http://code.google.com/appengine/docs/quotas.html#Billable_Quotas_and_Fixed_Quotas>,
> includes HTTPS) 1 gigabyte 56 megabytes/minute 1 gigabyte free; 1,046
> gigabytes maximum 740 megabytes/minute  Incoming Bandwidth
> (billable<http://code.google.com/appengine/docs/quotas.html#Billable_Quotas_and_Fixed_Quotas>,
> includes HTTPS) 1 gigabyte 56 megabytes/minute 1 gigabyte free; 1,046
> gigabytes maximum 740 megabytes/minute  CPU Time
> (billable<http://code.google.com/appengine/docs/quotas.html#Billable_Quotas_and_Fixed_Quotas>
> ) 6.5 CPU-hours 15 CPU-minutes/minute 6.5 CPU-hours free; 1,729 CPU-hours
> maximum 72 CPU-minutes/minuteNiels
> http://nielsmayer.com
>
> PS: although at 1 gigabyte outgoing bandwidth, and some of the sizable
> javascript libraries these days... you probably want to use
> http://webmuch.com/how-why-you-should-use-google-cdn/    alongside :-)
> _______________________________________________
> devs mailing list
> [email protected]
> http://lists.xwiki.org/mailman/listinfo/devs
>
>   


-- 
Ludovic Dubost
Blog: http://blog.ludovic.org/
XWiki: http://www.xwiki.com
Skype: ldubost GTalk: ldubost

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