I was recently looking at how to set up caching with JDO on Appengine, and there doesn't seem to be any good documentation. How do you make use of Memcache to avoid unnecessary hits to the datastore? I am using Android Studio / Gradle.
After some poking around, I came up with the following working solution.
Add the following lines to config files:
jdoconfig.xml
<property name="datanucleus.cache.level2.type" value="jcache"/>
<property name="datanucleus.cache.level2.cacheName" value="Anything"/>
build.gradle (for appengine module)
compile 'net.sf.jsr107cache:jsr107cache:1.1'
compile 'com.google.appengine:appengine-jsr107cache:1.9.17'
compile 'org.datanucleus:datanucleus-cache:3.1.3'
Of course, your mileage may vary, depending on your specific JDO setup.
Related
GAE/J team decided to retire App.cfg and asked everyone to move to Cloud SDK (based Maven or Gradle).
We have been using GAE/J for eight years, and we are using DataNucleus V1.
The reason that we still use DataNucleus V1 is that you can not upgrade to V2 or v3 without losing your information since they are not backward compatible (one to many relationships are not working after upgrade).
From some reason, we can not make DataNucleus V1 work with GAE/J Cloud SDK. Do you know if GAE/J stopped supporting this version? (and only support V2/V3?)
Update
The Ant task enhance-classes is working well if I am using GAE tools jar from version 1.9.6.3, when pointing to the current GAE tools jar (version 1.9.8.0) it fails enhacing classes.
Apparently GAE cloud sdk appengine-java version 1.9.8.0 did not include the following libraries:
google-cloud-sdk\platform\google_appengine\google\appengine\tools\java\lib\opt\tools->
datanucleus\v1(few jars files)
and
datanucleus\v2(few jars files)
The enhancer is looking for these jars in these directory structure which is missing.
Once you add these files and directories it is working well.
I also reported Google cloud team
https://issuetracker.google.com/issues/160624330
Update
After a few days that the issue I opened was confirmed as a "bug" and was assigned, someone decided that the bug is actually "Won't Fix (Intended Behavior)". If someone feels like me that this is a critical issue, please update your thoughts via the issue tracker link.
We use the Google Cloud Datastore Emulator. It autogenerates indexes.yaml. But as we did with the old Google Plugin for Eclipse, we want to get missing-index messages in the local development environment, and not later in cloud deployment. So, we want the Emulator to use our manually-maintained datastore-indexes.xml
How do we configure the use of a specific datastore-indexes.xml in the Google Cloud Datastore Emulator? I don't see any relevant command-line switches in the help text.
EDIT:
My answer was based on the dev_appserver emulator, not the current one. After running some tests, it appears that the emulator only has endpoints for a subset of the Datastore API methods, and index building (nor export/import for that matter) are available.
Leaving my previous answer to avoid repeated answers with the same wrong info:
_________
According to the docs, if autoGenerate="false" is in your datastore-indexes.xml, the development server should ignore the contents of WEB-INF/appengine-generated/datastore-indexes-auto.xml.
I think this might be what you're looking for, although I have not yet tested it.
I am about to install Solr on a production box. It will be the only Java applet running and be on the same box as the web server (nginx).
It seems there are two options.
Install Jetty separately and configure to use with Solr
Set Solr's embedded Jetty server to start as a service and just use that
Is there any performance benefit in having them separate?
I am a big fan of KISS, the less setup the better.
Thanks
If you want KISS there is no question: 2. stick to vanilla Solr distrib with included jetty.
Doing the work of installing an external servlet engine would make sense if you needed Tomcat for example, but just to use the same thing (Jetty) Solr already includes...no way.
Solr is still using jetty 6. So there would be some benefits if you can get the solr application to run in a recent jetty distribution. For example you could use jetty 9 and use features like SPDY to enhance the response times of your application.
However I have no idea or experience if it's possible to run the solr application standalone in a servlet engine.
Another option for running Solr and keeping it simple is to use Solr-Undertow which is a high performance with small footprint server for Solr. It is easy to use on local machines for development and also production. It supports simple config files for running instances with different data directories, ports and more. It also can run just by pointing it at a distribution .zip file without needing to unpack it.
(note, I am the author of Solr-Undertow)
Link here: https://github.com/bremeld/solr-undertow with releases under the "Releases" tab.
When i try to run gwt sample project it gives "RPC call failure.An error occurred while attempting to contact the server. Please check your network connection and try again". It was running good before but after i update programs and libraries it gives that error. Which update causes this error or there is other things?
Appengine version:1.7.0
GWT version:2.4.0
Eclipse version:4.2(juno)
JDK version:1.7.0_05
This may not be the problem you are facing but it seems to be the most frequent problem.
Let me predict - you last tried GWT four years ago and you hoarded the sample project hoping to pull it out one day.
And yesterday, you did pull it out. It kinda worked and then you decided to upgrade to the latest 2.4.0. (Actually the latest is 2.5.0-rc1).
Ooops. The web-inf/lib of your project is still faithfully using pre-version 2.2 gwt-servlet jar.
Nope, you can't do that. GWT-RPC data transfer format is version-unstable. Not guaranteed to be compatible from one version to the next.
Simple solution - recreate a new GWT project using the new Google plugin.
Then copy the src and web.xml of your project into the new project.
Or replace the gwt-servlet.jar with the latest. And if you usegwt-servlet-deps.jar, you would need to upgrade that too (but I doubt so, because if you did use gwt-servlet.deps.jar you wouldn't be asking this question).
But why would you keep the gwt sample from an old project?
The samples have remained quite the same over the years. Why not use the samples from the new GWT 2.4.0 download. You don't have to keep the samples. You should try to construct the projects for the samples afresh.
The GWT directory is found under Eclipse's plugins directory, under a long name. Like
plugins/com.google.gwt.eclipse.sdkbundle_2.4.0.v201205091048-rel-r37/gwt-2.4.0.
In which you will find the samples directory.
I've read the GAE docs, and I can't seem to figure out how to download all my entity data.
What I'd love to do is download the whole thing as a big TSV file (or something I can easily munge into one), so I can import my various entities into a spreadsheet and fiddle with them.
But I'm stuck at the starting gate. I don't understand the first few bits of the docs: "This document applies to apps that use the master/slave datastore. If your app uses the High Replication datastore..." -- I'm not even sure which I have, or how I would tell.
Assuming I have the simpler master/slave, the docs continue: "...you can use the Python appcfg.py tool by installing the Java version of the remote_api handler..." but, again, I'm not quite sure what they mean or where I find this appcfg.py tool.
Sorry for such a n00b question, but is there some sort of walk-through? I just want to download my datastore!
Thanks!
Master/Slave is the default (for now), so that's almost certainly what you're using. You can confirm at https://appengine.google.com/ -> app-id -> Administration -> Application Settings -> Datastore Replication Options.
To download your data, first install Remote API for Java, then use appcfg.py to download data:
appcfg.py download_data --application=<app-id> --url=http://<appname>.appspot.com/[remote_api_path] --filename=<data-filename>
There is nothing you need to do other than just follwiong the google's own documentaion. There is no workaround or walkthrough. I am not sure about java. In python , only thing you need to do is enable remote_api in your app.yaml.
appcfg.py can be found inside the root directory of appengine SDK.