[appengine-java] Filtering by Date using the Datastore Low Level API

2009-11-26 Thread Doug 
Good Evening Everyone,

I am working on creating an event calendar type of page and am having
trouble using the low level API and applying a filter to select events
that occur in the future.  The data that I am selecting has a property
of "display_until" that holds a date in -mm-dd hh:mm:ss format.

To select future events I started with the following code:
SimpleDateFormat formatter;
formatter = new SimpleDateFormat("-mm-dd hh:mm:ss");
Date date = new Date();
String query_date = formatter.format(date);

query.addSort("display_until", Query.SortDirection.ASCENDING);
query.addFilter("display_until",
com.google.appengine.api.datastore.Query.FilterOperator.GREATER_THAN,
query_date);

When I ran this code it did select future events, but not all of
them.  Currently I have some 2009 and some 2010 events.  It selected
the 2010 events, but not the December 2009 events.

Anyone have any suggestions for how I can select all of the future
events?

Thanks,
Doug

--

You received this message because you are subscribed to the Google Groups 
"Google App Engine for Java" group.
To post to this group, send email to google-appengine-j...@googlegroups.com.
To unsubscribe from this group, send email to 
google-appengine-java+unsubscr...@googlegroups.com.
For more options, visit this group at 
http://groups.google.com/group/google-appengine-java?hl=en.

[appengine-java] Re: Filtering by Date using the Datastore Low Level API

2009-11-27 Thread Doug 

Correcting the SimpleDateFormat solved the problem.  Thank you for
catching that!

Doug

On Nov 27, 5:26 am, m seleron  wrote:
> Hi,
>
> Though it might be unrelated.
> I think that Date and Time Patterns of SimpleDateFormat is [MM] Month
> in year [mm] Minute in hour.
>
> thanks.
>
> On 11月27日, 午後7:22, dflorey  wrote:
>
>
>
> > The filter will just do string comparison (how should it know that you
> > are comparing dates??)
> > To get proper sorting/filtering just store the date as time in millis
> > and it will work.
>
> > Cheers,
> > Daniel
>
> > On 27 Nov., 04:25, Doug  wrote:
>
> > > Good Evening Everyone,
>
> > > I am working on creating an event calendar type of page and am having
> > > trouble using the low level API and applying a filter to select events
> > > that occur in the future.  The data that I am selecting has a property
> > > of "display_until" that holds a date in -mm-dd hh:mm:ss format.
>
> > > To select future events I started with the following code:
> > >                 SimpleDateFormat formatter;
> > >                 formatter = new SimpleDateFormat("-mm-dd hh:mm:ss");
> > >                 Date date = new Date();
> > >                 String query_date = formatter.format(date);
>
> > >                 query.addSort("display_until", 
> > > Query.SortDirection.ASCENDING);
> > >                 query.addFilter("display_until",
> > > com.google.appengine.api.datastore.Query.FilterOperator.GREATER_THAN,
> > > query_date);
>
> > > When I ran this code it did select future events, but not all of
> > > them.  Currently I have some 2009 and some 2010 events.  It selected
> > > the 2010 events, but not the December 2009 events.
>
> > > Anyone have any suggestions for how I can select all of the future
> > > events?
>
> > > Thanks,
> > > Doug

--

You received this message because you are subscribed to the Google Groups 
"Google App Engine for Java" group.
To post to this group, send email to google-appengine-j...@googlegroups.com.
To unsubscribe from this group, send email to 
google-appengine-java+unsubscr...@googlegroups.com.
For more options, visit this group at 
http://groups.google.com/group/google-appengine-java?hl=en.

[appengine-java] Re: HIPAA compliance

2010-01-03 Thread Doug 


>From reading the Google Health FAQ I think the answer to your question
is no, but they don't need to be.



Is Google Health covered by HIPAA?

Unlike a doctor or health plan, Google Health is not regulated by the
Health Insurance Portability and Accountability Act (HIPAA), a federal
law that establishes data confidentiality standards for patient health
information. This is because Google does not store data on behalf of
health care providers. Instead, our primary relationship is with you,
the user. Under HIPAA, you have a right to obtain a copy of your
medical records. If you choose to use Google Health, we'll help you
store and manage your medical records online.

Although Google Health is not covered by HIPAA, we are committed to
protecting your privacy. Our Google Health privacy policy governs what
information Google Health collects and how we use it, and any
violation of that policy can be enforced by the Federal Trade
Commission, which takes action against companies that engage in unfair
and deceptive trade practices -- including violations of their privacy
policies.



On Jan 3, 11:17 am, Pion  wrote:
> http://www.slideshare.net/bess.ho/google-health-architecture-api
> (slide 28) shows that Google Health is using Google App Engine.
>
> Is Google App Engine HIPAA (Health Insurance Portability and
> Accountability Act -http://en.wikipedia.org/wiki/HIPAA) compliance ?

--

You received this message because you are subscribed to the Google Groups 
"Google App Engine for Java" group.
To post to this group, send email to google-appengine-j...@googlegroups.com.
To unsubscribe from this group, send email to 
google-appengine-java+unsubscr...@googlegroups.com.
For more options, visit this group at 
http://groups.google.com/group/google-appengine-java?hl=en.

[appengine-java] Datastore Reads

2011-10-01 Thread Doug 
Good Morning,

I am working to tune my application to make the most efficient use 
resources.  Over the last several days I have been trying to reduce the 
number of 'datastore reads' that are needed, but I have been having trouble 
determining what a datastore read is.  My initial assumption was that it was 
like a write in that each item you read from the datastore was a read, but I 
have reduced the number of 'rows' of data that I am reading by over half and 
there wasn't any change in the datastore reads.  

I am now wondering if a datastore read is more like a fetch from a database 
where in a single fetch you could be getting 1 or more rows of data. So, do 
anyone know what a datastore read is or can you point me in the right 
direction for documentation on this?

Thanks,
Doug

-- 
You received this message because you are subscribed to the Google Groups 
"Google App Engine for Java" group.
To view this discussion on the web visit 
https://groups.google.com/d/msg/google-appengine-java/-/RnvUDZnGnyMJ.
To post to this group, send email to google-appengine-java@googlegroups.com.
To unsubscribe from this group, send email to 
google-appengine-java+unsubscr...@googlegroups.com.
For more options, visit this group at 
http://groups.google.com/group/google-appengine-java?hl=en.

[appengine-java] Java 5 and Remote API

2011-12-24 Thread Doug 
Good Morning,
 
I am trying to use the remote API to access the datastore in a Java 5 
envirotment.  Currently I am receiving the error below when trying to build 
the application.  Is there a way to get a Java 5 verions of the 
appengine-api, appengine-remote-api, and appengine-tools.api jars?
 
"class file has wrong version 50.0, should be 49.0"
 
Thanks,
Doug

-- 
You received this message because you are subscribed to the Google Groups 
"Google App Engine for Java" group.
To view this discussion on the web visit 
https://groups.google.com/d/msg/google-appengine-java/-/1Zjug3EggJ8J.
To post to this group, send email to google-appengine-java@googlegroups.com.
To unsubscribe from this group, send email to 
google-appengine-java+unsubscr...@googlegroups.com.
For more options, visit this group at 
http://groups.google.com/group/google-appengine-java?hl=en.

[appengine-java] Re: Any inputs for How to use the DataStore for Java?

2011-12-28 Thread Doug 
Those are all great references indeed. However, I'm still stumped on this 
one which should be basic.

Using the Low Level API, I still cannot why String Properties break on 
special characters. 

thisEntity.setProperty("stringDescription" ,"Save 20% Off anything in 
store");

A little help on how to (convert?) and store (then get...) Strings 
containing non-alphanumeric characters with LLAPI?

Many Thanks
Doug

-- 
You received this message because you are subscribed to the Google Groups 
"Google App Engine for Java" group.
To view this discussion on the web visit 
https://groups.google.com/d/msg/google-appengine-java/-/Whb8noU7rZMJ.
To post to this group, send email to google-appengine-java@googlegroups.com.
To unsubscribe from this group, send email to 
google-appengine-java+unsubscr...@googlegroups.com.
For more options, visit this group at 
http://groups.google.com/group/google-appengine-java?hl=en.

[appengine-java] Support of Java Keystore Files for SSL Connections

2012-01-29 Thread Doug 
Hello All,

Is there a way in GAE to access certificates that are stored in Java 
Keystore files and then have GAE use those certificates when making a 
connection to call a web service?  I can do this outside of GAE by 
specifying the location of keystore file using 
'System.setProperty("javax.net.ssl.keyStore","C:\\myKeys.jks");' and then 
specifying the keystore password using 
'System.setProperty("javax.net.ssl.keyStorePassword","x");'

I have been successful in calling other web services from GAE.  I am just 
unsure how to tell GAE to use specific SSL certificates in making the 
connection.

Thanks,
Doug

-- 
You received this message because you are subscribed to the Google Groups 
"Google App Engine for Java" group.
To view this discussion on the web visit 
https://groups.google.com/d/msg/google-appengine-java/-/J0oa8lqe0ckJ.
To post to this group, send email to google-appengine-java@googlegroups.com.
To unsubscribe from this group, send email to 
google-appengine-java+unsubscr...@googlegroups.com.
For more options, visit this group at 
http://groups.google.com/group/google-appengine-java?hl=en.

[appengine-java] Delete using low-level API

2010-10-16 Thread Doug 
Good Morning,


If I have the key and/or ID/name of a datastore object how can I delete
it using the low-level API? I have looked though the java doc, but have
not been able to find a delete method.


Thanks,
Doug

-- 
You received this message because you are subscribed to the Google Groups 
"Google App Engine for Java" group.
To post to this group, send email to google-appengine-j...@googlegroups.com.
To unsubscribe from this group, send email to 
google-appengine-java+unsubscr...@googlegroups.com.
For more options, visit this group at 
http://groups.google.com/group/google-appengine-java?hl=en.

[appengine-java] Re: Delete using low-level API

2010-10-16 Thread Doug 
I think I found it. the delete method is in DatastoreService.


Doug

-- 
You received this message because you are subscribed to the Google Groups 
"Google App Engine for Java" group.
To post to this group, send email to google-appengine-j...@googlegroups.com.
To unsubscribe from this group, send email to 
google-appengine-java+unsubscr...@googlegroups.com.
For more options, visit this group at 
http://groups.google.com/group/google-appengine-java?hl=en.

Re: [appengine-java] GAE deployment failure

2010-11-18 Thread Doug 
I have the same issue. It started about an hour ago.


Anyone have any ideas how to resolve?



Doug

-- 
You received this message because you are subscribed to the Google Groups 
"Google App Engine for Java" group.
To post to this group, send email to google-appengine-j...@googlegroups.com.
To unsubscribe from this group, send email to 
google-appengine-java+unsubscr...@googlegroups.com.
For more options, visit this group at 
http://groups.google.com/group/google-appengine-java?hl=en.

[appengine-java] Task Queue API Update

2011-01-23 Thread Doug 


Good Afternoon All,

 I am working to convert from the Task Queue Labs API to the non-labs API 
version.  I am finding it slightly more difficult than I initially 
anticipated.  It appears that how I was adding tasks to the queue is not 
compatible with the non-labs API.  If I just update the imports to bring in 
the new API I get the error “The method url(String) is undefined for the 
type TaskOptions.Builder”.  I  have provide some example of my code below, 
if anyone else has converted can you give me some guidance on what I am 
doing wrong?

 

Current code, using the Labs API:
*import* *com.google.appengine.api.labs.taskqueue.Queue*;
*import* *com.google.appengine.api.labs.taskqueue.QueueFactory*;
*import* *com.google.appengine.api.labs.taskqueue.TaskOptions*;
*import* *com.google.appengine.api.labs.taskqueue.TaskOptions.Method*;
*import* *com.google.appengine.api.labs.taskqueue.TaskOptions.Builder*.*;

…

Queue add_queue = QueueFactory.getQueue("add");
…

for (int i = 1; i < Item_counter; i++) {

add_queue.add(TaskOptions.Builder.url("/add?item="+ItemURL[i]).method(Method.GET));
}

 

Code using the non-Labs API

import com.google.appengine.api.taskqueue.Queue;
import com.google.appengine.api.taskqueue.QueueFactory;
import com.google.appengine.api.taskqueue.TaskOptions;
import com.google.appengine.api.taskqueue.TaskOptions.Method;
import static com.google.appengine.api.taskqueue.TaskOptions.Builder.*;

 

TaskOptions TOdefault = 
com.google.appengine.api.taskqueue.TaskOptions.Builder.withDefaults();

…

for (int i = 1; i < Item_counter; i++) {

TaskOptions TO = new TaskOptions(TOdefault);
TO.url("/add");
TO.param("item", itemURL[i]);
TO.method(Method.GET);
add_queue.add(TO);
}


The new code compiles and will “run”, but I get all kinds of null pointer 
exceptions from the tasks when they try to run.  If I switch back to the 
labs API it works perfectly.  Can anyone help me understand what I need to 
do to either get my original code to work with the new API and/or what I did 
incorrectly with the updated code?


Thanks,
Doug

-- 
You received this message because you are subscribed to the Google Groups 
"Google App Engine for Java" group.
To post to this group, send email to google-appengine-java@googlegroups.com.
To unsubscribe from this group, send email to 
google-appengine-java+unsubscr...@googlegroups.com.
For more options, visit this group at 
http://groups.google.com/group/google-appengine-java?hl=en.

[appengine-java] Re: how to query TaskQueue for count of running/pending tasks?

2011-01-23 Thread Doug 

There was another thread on this same topic a few months back.  I am not 
able to find it right now, but I believe that I remember that someone was 
using URL Fetch to fetch 
"https://appengine.google.com/queues?&app_id=&version_id=xx"; and 
then parsing the page to determine the number of tasks on each queue.  I 
don't recall how they were handling authentication. 

Doug

-- 
You received this message because you are subscribed to the Google Groups 
"Google App Engine for Java" group.
To post to this group, send email to google-appengine-java@googlegroups.com.
To unsubscribe from this group, send email to 
google-appengine-java+unsubscr...@googlegroups.com.
For more options, visit this group at 
http://groups.google.com/group/google-appengine-java?hl=en.

[appengine-java] Data via FTP

2011-03-25 Thread Doug 
Good Afternoon All,

In App Engine is there any way to get a file via FTP or have a file
FTPed to the application?  I wanted to be able to get a feed of data
into my application from a vendor that only supports sending data via
FTP.  I did some initial searching and it appears that there is no way
to either receive the file via FTP into an application or get a file
via FTP.

Any suggestions?  I have a Google Apps account, but I don's see
anything that I could use in combination with App Engine to make this
work.

I appreciate any help and/or ideas that anyone has.

Thanks,
Doug

-- 
You received this message because you are subscribed to the Google Groups 
"Google App Engine for Java" group.
To post to this group, send email to google-appengine-java@googlegroups.com.
To unsubscribe from this group, send email to 
google-appengine-java+unsubscr...@googlegroups.com.
For more options, visit this group at 
http://groups.google.com/group/google-appengine-java?hl=en.

Re: [appengine-java] Data via FTP

2011-03-26 Thread Doug 
Thank you.

I stared the item.  This would be a great feature to add.

Doug

-- 
You received this message because you are subscribed to the Google Groups 
"Google App Engine for Java" group.
To post to this group, send email to google-appengine-java@googlegroups.com.
To unsubscribe from this group, send email to 
google-appengine-java+unsubscr...@googlegroups.com.
For more options, visit this group at 
http://groups.google.com/group/google-appengine-java?hl=en.

[appengine-java] Datastore and Polymorphic support getObjectByID(Parent.class, childKey)

2010-07-12 Thread Doug Daniels 
I'm trying to model a polymorphic relationship in JDO, List
where each GameRound could be either a TextRound or PictureRound.

I've followed the documentation and modeled the association as a
List as described:
http://code.google.com/appengine/docs/java/datastore/relationships.html#Polymorphic_Relationships

// ... imports ...

@PersistenceCapable
public class Chef {
@PrimaryKey
@Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
private Key key;

@Persistent
private Key favoriteRecipe;
}


Here is my Game object:

@PersistenceCapable
public class Game {

@PrimaryKey
@Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
private Key key;

@Persistent
private List rounds = new ArrayList();
...
}


@PersistenceCapable
@Inheritance(strategy = InheritanceStrategy.SUBCLASS_TABLE)
public class GameRound {
...
}


@PersistenceCapable
public class SentenceRound extends GameRound {
@PrimaryKey
@Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
private Key key;

...
}

@PersistenceCapable
public class PictureRound extends GameRound {
@PrimaryKey
@Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
private Key key;
...
}

The trouble is in my Game object I iterate through the rounds and try
to do a persistenceManager.getObjectById(GameRound.class, key) and I
get the following exception:

WARNING: /viewGames.jsp
javax.jdo.JDOFatalUserException: Exception converting SentenceRound(7)
to an internal key.
at
org.datanucleus.store.appengine.jdo.DatastoreJDOPersistenceManager.getObjectById(DatastoreJDOPersistenceManager.java:
68)
at org.apache.jsp.viewGames_jsp._jspService(viewGames_jsp.java:121)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:94)


What's the proper way to retrieve a polymorphic key relationship (for
example how would you do it in the Appengine Chef example?).

My only other option is to model the relationship as mutually
exclusive properties of the GameRound (and manage that in my
application logic).

@PersistenceCapable
@Inheritance(strategy = InheritanceStrategy.SUBCLASS_TABLE)
public class GameRound {

@PrimaryKey
@Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
private Key key;

//Model relationships as optional components because JDO and
Appengine don't support
//Polymorphic relationships well.

@Persistent
private SentenceRound sentenceRound;

@Persistent
private PictureRound pictureRound;

...
}

-- 
You received this message because you are subscribed to the Google Groups 
"Google App Engine for Java" group.
To post to this group, send email to google-appengine-j...@googlegroups.com.
To unsubscribe from this group, send email to 
google-appengine-java+unsubscr...@googlegroups.com.
For more options, visit this group at 
http://groups.google.com/group/google-appengine-java?hl=en.

[appengine-java] Use BlobstoreService and ImageService to upload/serve images drawn from an HTML5 canvas Paintweb JS Library

2010-09-19 Thread Doug Daniels 
I'm working on an Appengine application in Java that allows users to
upload images drawn through an HTML5 canvas library called PaintWeb
(http://code.google.com/p/paintweb/).

Currently I have a servlet that receives the XMLHttpRequest POST from
the paintweb javascript library as a formencoded image.

1. Paintweb.js library sends XMLHttpRequest POST
  send   = 'dataURL=' + encodeURIComponent(ev.dataURL),
  headers= {'Content-Type': 'application/x-www-form-
urlencoded'};

2. A custom servlet decodes the form encoded image data as a blob and
stores that in the Datastore with an associated Drawing entity

3 Custom servlet serves the Blob's in the datastore as
ContentType("image/png")

I'm curious if I can use the new BlobstoreService and ImageService
features to upload my HTML5 canvas images and serve them as pure Blobs
(as shown in this tutorial
http://ikaisays.com/2010/09/08/gwt-blobstore-the-new-high-performance-image-serving-api-and-cute-dogs-on-office-chairs/)

According to the documentation (http://code.google.com/appengine/docs/
java/blobstore/overview.html#Uploading_a_Blob) it seems like the major
stopping point is that I need to POST a form with:
 

Which I don't think is possible from Paintweb.

Possibly a work around would be if there was some way on the server
side to store a blob in the Blobstorage (instead of the datastore) so
that you could reap the benefits of not using your CPU quota to serve
images.

-- 
You received this message because you are subscribed to the Google Groups 
"Google App Engine for Java" group.
To post to this group, send email to google-appengine-j...@googlegroups.com.
To unsubscribe from this group, send email to 
google-appengine-java+unsubscr...@googlegroups.com.
For more options, visit this group at 
http://groups.google.com/group/google-appengine-java?hl=en.

[appengine-java] Re: Use BlobstoreService and ImageService to upload/serve images drawn from an HTML5 canvas Paintweb JS Library

2010-09-19 Thread Doug Daniels 
Is it possible or even a good idea to use the Appengine URL Fetch
service and forward the image blob upload to the Blobstorage
"createUploadURL()" from the server side.

http://code.google.com/appengine/docs/java/urlfetch/usingjavanet.html

It seems like it could be possible, but not sure it would save me
resources in the long run (the images are simple small drawings that
could be viewed many many more times than the upload time so I feel
like I'd get benefit storing/serving from the BlobstoreService.

On Sep 19, 3:02 pm, Doug Daniels  wrote:
> I'm working on an Appengine application in Java that allows users to
> upload images drawn through an HTML5 canvas library called PaintWeb
> (http://code.google.com/p/paintweb/).
>
> Currently I have a servlet that receives the XMLHttpRequest POST from
> the paintweb javascript library as a formencoded image.
>
> 1. Paintweb.js library sends XMLHttpRequest POST
>           send       = 'dataURL=' + encodeURIComponent(ev.dataURL),
>           headers    = {'Content-Type': 'application/x-www-form-
> urlencoded'};
>
> 2. A custom servlet decodes the form encoded image data as a blob and
> stores that in the Datastore with an associated Drawing entity
>
> 3 Custom servlet serves the Blob's in the datastore as
> ContentType("image/png")
>
> I'm curious if I can use the new BlobstoreService and ImageService
> features to upload my HTML5 canvas images and serve them as pure Blobs
> (as shown in this 
> tutorialhttp://ikaisays.com/2010/09/08/gwt-blobstore-the-new-high-performance...)
>
> According to the documentation (http://code.google.com/appengine/docs/
> java/blobstore/overview.html#Uploading_a_Blob) it seems like the major
> stopping point is that I need to POST a form with:
>      
>
> Which I don't think is possible from Paintweb.
>
> Possibly a work around would be if there was some way on the server
> side to store a blob in the Blobstorage (instead of the datastore) so
> that you could reap the benefits of not using your CPU quota to serve
> images.

-- 
You received this message because you are subscribed to the Google Groups 
"Google App Engine for Java" group.
To post to this group, send email to google-appengine-j...@googlegroups.com.
To unsubscribe from this group, send email to 
google-appengine-java+unsubscr...@googlegroups.com.
For more options, visit this group at 
http://groups.google.com/group/google-appengine-java?hl=en.

[appengine-java] Sharded Counters in Java not using Transactions?

2010-09-21 Thread Doug Daniels 
I'm going through the Sharded Counters example in Java:
http://code.google.com/appengine/articles/sharding_counters.html

I have a question about the implementation of the increment method. In
python it explicitly wraps the get() and increment in a transaction.
In the Java example it just retrieves it and sets it. I'm not sure I
fully understand the Datastore and transactions but it seems like the
critical update section should be wrapped in a datastore transaction.
Am I missing something?

Original code:
public void increment() {
PersistenceManager pm = PMF.get().getPersistenceManager();

Random generator = new Random();
int shardNum = generator.nextInt(NUM_SHARDS);

try {
  Query shardQuery = pm.newQuery(SimpleCounterShard.class);
  shardQuery.setFilter("shardNumber == numParam");
  shardQuery.declareParameters("int numParam");

  List shards =
  (List) shardQuery.execute(shardNum);
  SimpleCounterShard shard;

  // If the shard with the passed shard number exists, increment
its count
  // by 1. Otherwise, create a new shard object, set its count to
1, and
  // persist it.
  if (

Transactional code:

public void increment() {
PersistenceManager pm = PMF.get().getPersistenceManager();

Random generator = new Random();
int shardNum = generator.nextInt(NUM_SHARDS);

try {
  Query shardQuery = pm.newQuery(SimpleCounterShard.class);
  shardQuery.setFilter("shardNumber == numParam");
  shardQuery.declareParameters("int numParam");

  List shards =
  (List) shardQuery.execute(shardNum);
  SimpleCounterShard shard;

  // If the shard with the passed shard number exists, increment
its count
  // by 1. Otherwise, create a new shard object, set its count to
1, and
  // persist it.
  if (shards != null && !shards.isEmpty()) {
Transaction tx = pm.currentTransaction();

try {
tx.begin();
//I believe in a transaction objects need to be loaded 
by ID (can't
use the outside queried entity)
Key shardKey =
KeyFactory.Builder(SimpleCounterShard.class.getSimpleName(),
shards.get(0).getID())
shard =  pm.getObjectById(SimpleCounterShard.class, 
shardKey);
shard.setCount(shard.getCount() + 1);
tx.commit();
} finally {
if (tx.isActive()) {
tx.rollback();
}
}

  } else {
shard = new SimpleCounterShard();
shard.setShardNumber(shardNum);
shard.setCount(1);
  }

  pm.makePersistent(shard);
} finally {
  pm.close();
}
  }
}

-- 
You received this message because you are subscribed to the Google Groups 
"Google App Engine for Java" group.
To post to this group, send email to google-appengine-j...@googlegroups.com.
To unsubscribe from this group, send email to 
google-appengine-java+unsubscr...@googlegroups.com.
For more options, visit this group at 
http://groups.google.com/group/google-appengine-java?hl=en.

[appengine-java] Re: Sharded Counters in Java not using Transactions?

2010-09-24 Thread Doug Daniels 
I posted the question on Stackoverflow and the consensus is that it
should be wrapped in a transaction.
http://stackoverflow.com/questions/3782296/java-google-appengine-sharded-counters-without-transactions

I also opened an Appengine issue (is this the right way to report
issues in documentation?):
http://code.google.com/p/googleappengine/issues/detail?id=3778&q=sharded&colspec=ID%20Type%20Status%20Priority%20Stars%20Owner%20Summary%20Log%20Component


On Sep 21, 12:24 pm, Doug Daniels  wrote:
> I'm going through the Sharded Counters example in 
> Java:http://code.google.com/appengine/articles/sharding_counters.html
>
> I have a question about the implementation of the increment method. In
> python it explicitly wraps the get() and increment in a transaction.
> In the Java example it just retrieves it and sets it. I'm not sure I
> fully understand the Datastore and transactions but it seems like the
> critical update section should be wrapped in a datastore transaction.
> Am I missing something?
>
> Original code:
> public void increment() {
>     PersistenceManager pm = PMF.get().getPersistenceManager();
>
>     Random generator = new Random();
>     int shardNum = generator.nextInt(NUM_SHARDS);
>
>     try {
>       Query shardQuery = pm.newQuery(SimpleCounterShard.class);
>       shardQuery.setFilter("shardNumber == numParam");
>       shardQuery.declareParameters("int numParam");
>
>       List shards =
>           (List) shardQuery.execute(shardNum);
>       SimpleCounterShard shard;
>
>       // If the shard with the passed shard number exists, increment
> its count
>       // by 1. Otherwise, create a new shard object, set its count to
> 1, and
>       // persist it.
>       if (
>
> Transactional code:
>
> public void increment() {
>     PersistenceManager pm = PMF.get().getPersistenceManager();
>
>     Random generator = new Random();
>     int shardNum = generator.nextInt(NUM_SHARDS);
>
>     try {
>       Query shardQuery = pm.newQuery(SimpleCounterShard.class);
>       shardQuery.setFilter("shardNumber == numParam");
>       shardQuery.declareParameters("int numParam");
>
>       List shards =
>           (List) shardQuery.execute(shardNum);
>       SimpleCounterShard shard;
>
>       // If the shard with the passed shard number exists, increment
> its count
>       // by 1. Otherwise, create a new shard object, set its count to
> 1, and
>       // persist it.
>       if (shards != null && !shards.isEmpty()) {
>             Transaction tx = pm.currentTransaction();
>
>         try {
>             tx.begin();
>                         //I believe in a transaction objects need to be 
> loaded by ID (can't
> use the outside queried entity)
>                         Key shardKey =
> KeyFactory.Builder(SimpleCounterShard.class.getSimpleName(),
> shards.get(0).getID())
>                         shard =  pm.getObjectById(SimpleCounterShard.class, 
> shardKey);
>                         shard.setCount(shard.getCount() + 1);
>             tx.commit();
>         } finally {
>             if (tx.isActive()) {
>                 tx.rollback();
>             }
>         }
>
>       } else {
>         shard = new SimpleCounterShard();
>         shard.setShardNumber(shardNum);
>         shard.setCount(1);
>       }
>
>       pm.makePersistent(shard);
>     } finally {
>       pm.close();
>     }
>   }
>
>
>
>
>
>
>
> }

-- 
You received this message because you are subscribed to the Google Groups 
"Google App Engine for Java" group.
To post to this group, send email to google-appengine-j...@googlegroups.com.
To unsubscribe from this group, send email to 
google-appengine-java+unsubscr...@googlegroups.com.
For more options, visit this group at 
http://groups.google.com/group/google-appengine-java?hl=en.