Weekly Reports

Week 1 (23^rd April - 1^th May) : Community Bonding Period

Title

Explanation

Next week plan

Mentors Comments

Community Bonding Period
Fixing issue which are directly related/part of project

Setup dev environment for Gora

Went through MemStore implementation

provided a fix for https://issues.apache.org/jira/browse/GORA-447

Go through Gora Datastore implementations
Hazelcast JCache Documentation/samples

Kevin Ratnasekera needs to send Lewis John McGibbney links to his reports on a weekly basis. There has been little community engagement and this needs to change if the community is to understand what this project is all about. Additionally, absolutely very little communication has taken place between student and mentor. This needs to change!

Week 2 (1^th May - 7^th May) : Community Bonding Period

Title

Explanation

Next week plan

Mentors Comments

Community Bonding Period
Fixing issue which are directly related/part of project

Went through Hazelcast JCache Documentation/samples
http://docs.hazelcast.org/docs/3.3/manual/html/jcache.html

https://hazelcast.com/use-cases/caching/jcache-provider/

Go through Gora Datastore implementations
Hazelcast JCache Documentation/samples
Fixing related issues

Kevin Ratnasekera needs to send Lewis John McGibbney links to his reports on a weekly basis. There has been little community engagement and this needs to change if the community is to understand what this project is all about. Additionally, absolutely very little communication has taken place between student and mentor. This needs to change!

Week 3 (7^th May - 14^th May) : Community Bonding Period

Title

Explanation

Next week plan

Mentors Comments

Community Bonding Period
Fixing issue which are directly related/part of project

Further went through Hazelcast JCache Documentation/samples
http://docs.hazelcast.org/docs/3.3/manual/html/jcache.html

provided a fix for https://issues.apache.org/jira/browse/GORA-274

Lewis John McGibbney Please find the sample here. I have done some modification to the Hazelcast-JCache Sample which used to demonstrate database caching.

https://github.com/djkevincr/JCache-Samples/blob/master/hazelcast-code-samples/jcache/src/main/java/com/hazelcast/examples/application/Main.java

Lewis John McGibbney

Apologizes for any inconvenience.

This sample demonstrate basic database caching using Hazelcast.

Database calls such as read have inherent latency. What caches does is that provides in memory storage for data so that it avoids database hit when each time the data is retrieved from database thus avoiding the latency associated. The same concepts can be applied to writes as well.

Hazelcast provides Caches which interface is pretty similar to Java HashMaps which can be used to implement Caches. These maps should implement CacheLoader and CacheWritter interfaces which basically handles reading and writing data from back end database to Cache.

This sample is not written in mindset of distributed caching. In line 121 I have modified the hazelcast.xml so that it forms a cluster when main program is run on several JVMs. I have tested the scenarios running program in several JVMs and find out that caching is correctly working for distributed mode.

Go through Apache Gora Codebase, Datastore Implementations
Hazelcast JCache Documentation/samples
Fixing related issues

Kevin Ratnasekera it would be nice to see evidence of your Hazelcast JCache work. Where is this? I do not see a clone of Hazelcast in your Github repository. You should clone it and work from master branch https://github.com/hazelcast/hazelcast/. Please also consider addressing issues which are on the Gora roadmap for the next release instead of very trivial issues.
https://issues.apache.org/jira/browse/GORA/?selectedTab=com.atlassian.jira.jira-projects-plugin:roadmap-panel

Kevin Ratnasekera can you point specifically to the line numbers and also document your code to explain what the cache'ing does and how it is implemented? Please try and be more verbose when inserting links into these weekly reports. If it is done correctly the first time then you only need to do it once. If the links are useless then I will keep asking you to change them and it will waste both you and my own time. Thanks

Week 4 (14^th May - 21^th May) : Community Bonding Period

Title	Explanation	Next week plan	Mentors Comments
Community Bonding Period Fixing issue which are directly related/part of project	I have setup HBase and ran queries over it using gora-hbase data store. This setup will be useful for implementing caching over data store. Followed tutorial on Log manager. Followed sample on back-end database caching using Hazelcast JCache Followed tutorial on writing data stores for gora. Writing a new DataStore for Gora HOW_TO	Start implementing JCache data-store. Work on fixing issues.	Please send me a link to your gora-jcache module and gora-hazelcast branch. It would be good for your to provide a class diagram of your intentions before you progress with work. I would like to see this. Thanks

Week 5 (21^th May - 28^th May) : Coding Period

Title

Explanation

Next week plan

Mentors Comments

Coding Period

Followed tutorial on writing data stores for gora. Writing a new DataStore for Gora HOW_TO

Created initial project structure on branch GORA-409 committed the changes

https://github.com/djkevincr/gora/commits/GORA-409

I am glad that Kevin Ratnasekera has started coding the gora-jcache module. He should continue to work on other Gora issues if he has the time and should also keep Lewis John McGibbney updated with his progress. Thanks, this is much better.

Week 6 (28^th May -5^thJune) : Coding Period

Title	Explanation	Next week plan	Mentors Comments
Coding Period	Researched on implementing JCache store and finalized my intentions on coding. I had a look at different data store implementation for Gora and different JCache solutions. Finally came up with a rough design and class diagram what I will be coding in next few months. https://docs.google.com/document/d/15NTbAsU9USniDkMmgzVORN3ZjymlUVGGoNQgYXBz4Wc/edit?usp=sharing	Based on design I came up with and based on mentors feedback I will carryout the implementation.

Week 7 (5^th June -12^thJune) : Coding Period

Title	Explanation	Next week plan	Mentors Comments
Coding Period	I have came up with the initial POC for this and committed to the project branch. POC is based on basic design. https://docs.google.com/document/d/15NTbAsU9USniDkMmgzVORN3ZjymlUVGGoNQgYXBz4Wc/edit?usp=sharing	Based on design I came up with and based on mentors feedback I will carryout the implementation.

Week 8 (12^th June -19^thJune) : Coding Period

Title

Explanation

Next week plan

Mentors Comments

Coding Period

I am currently testing the POC version. I am using GORA HBase datastore to fetch avro data beans into the cache. I am getting following exception.

The reasons for the following stack trace is that Avro data beans does not implement serialized JAVA interface. Hazelcast caches uses pure java serialization to keep data beans into in memory format. HBase store always returns string ( Char Sequence ) as in Avro Utf8 when data beans are retrieved from data store that leads to following exception. Avro Utf8 is not in java serializable form. ( Does implement serializable interface ) I will for work this for a better solution. However I have tested code POC for Avro databeans over other datatypes which perfectly worked fine for me.

Exception in thread "main" com.hazelcast.nio.serialization.HazelcastSerializationException: java.io.NotSerializableException: org.apache.avro.util.Utf8
   at com.hazelcast.internal.serialization.impl.SerializationUtil.handleException(SerializationUtil.java:61)
   at com.hazelcast.internal.serialization.impl.AbstractSerializationService.toBytes(AbstractSerializationService.java:141)
   at com.hazelcast.internal.serialization.impl.AbstractSerializationService.toData(AbstractSerializationService.java:116)
   at com.hazelcast.internal.serialization.impl.AbstractSerializationService.toData(AbstractSerializationService.java:104)
   at com.hazelcast.cache.impl.AbstractInternalCacheProxy.putAsyncInternal(AbstractInternalCacheProxy.java:190)
   at com.hazelcast.cache.impl.AbstractCacheProxy.put(AbstractCacheProxy.java:200)
   at com.hazelcast.cache.impl.CacheProxy.put(CacheProxy.java:75)
   at com.hazelcast.cache.impl.CacheProxy.put(CacheProxy.java:140)
   at org.apache.gora.jcache.store.JCacheStore.put(JCacheStore.java:104)
   at org.apache.gora.jcache.store.JCacheStore.put(JCacheStore.java:41)
   at org.apache.gora.tutorial.log.LogManager.main(LogManager.java:262)
   at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
   at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
   at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
   at java.lang.reflect.Method.invoke(Method.java:606)
   at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144)