Sunday, September 11, 2016

Oracle Workspace Manager - Basic POC with Spring Boot and Flyleaf

Working with a process to update configuration and master data within an enterprise is always a challenging task. While investigating possible solutions on how to have someone change data via a UI, then have those changes tested, signed off and approved before taking it to production. I stumbled on to Oracle Workspace Manager.
According to their developer docs, it seemed fit this use case exactly:

Manage a collection of updates and insertions as a unit before incorporating them into production data
Workspace Manager lets you review changes and roll back undesirable ones before making the changes public. Until you make the changes public, they are invisible to other users of the database, who will access only the regular production data. You can organize the changes in a simple set of workspaces or in a complex workspace hierarchy. A typical example might be a life sciences application in which Workspace Manager supports the discovery and quality assurance (QA) processes by managing a collection of updates before they are merged with the production data.


You could think of Oracle Workspace Manager as light "git"-like db versioning. 
Simply put:

  1. You create a workspace (branch)... 
  2. You make your changes there.. other people can connect to your workspace .. also make changes... or alternatively create their own branch from yours.
  3. You can refresh (fetch / merge) your workspace and resolve any conflicts that arise.
  4. Once everything is sorted and all is well with your changes you merge it back into the "LIVE" (origin: develop / master) workspace.

I used an existing Docker image of a oracle standard edition version. Oracle Workspace manager is not available on XE unfortunately. This is a rather large image, and it does take a couple minutes to initialise. The image is available on here on Docker Hub.


Connect database with following setting:
hostname: localhost
port: 1521
sid: xe
service name: xe.oracle.docker
username: system
password: oracle

To connect using sqlplus:
sqlplus system/oracle@//localhost:1521/xe.oracle.docker
To connect on mac os - install instantclient and run from there:

./instantclient_12_1/sqlplus system/oracle@local


To setup the initial DB I tried out Flyway. All quite simple and easy to implement. 
Under resources/db/migration there are a number of sql files that do the initial database setup.

  1. create the tables: CODE and CODE_TYPE, 
  2. insert initial data 
  3. enable versioning on those tables.

When you enable versioning the following happens, the table is renamed and a view is created allowing the "recording" of changes that occur.

Reference: (oracle presentation available here)



So after the initial setup you will seen a number of tables and views:



To try this out...

  1. Get the Oracle Docker image
  2. Once the DB is started... run the boot DataApplication.
  3. Use Postman on the REST resources below

To check the current workspace:
GET: http://localhost:9119/poc/workspace
To select all the information from the code table for the current workspace:
GET: http://localhost:9119/poc/workspace/data/code
Create code in the current workspace:
POST: http://localhost:9119/poc/workspace/data/code
BODY: 
{
"id":2,
"descr": "some code",
"type": 1
}
To change workspace (LIVE is default and available):
PUT: http://localhost:9119/poc/workspace/{workspaceName}
To create a workspace:
POST: http://localhost:9119/poc/workspace/{workspaceName}
To remove a workspace:
DELETE: http://localhost:9119/poc/workspace/{workspaceName}
To merge a workspace:
PUT: http://localhost:9119/poc/workspace/merge/{workspaceName}


These REST resources just wrap some of the functions from the DBMS_WM Package
This is maybe just the tip of a iceberg, as there is a ton of functionality available from this package.

All the code is available here.


Wednesday, September 7, 2016

Re-Inspired

It has been a very long time since I last posted.
 Due to some crazy work pressures and a couple months of working 2 jobs, I just could not find the time nor inspiration to contribute to this blog.

However today a work colleague sent me the following: 52 Technologies in 2016

It's awesome.
It reminded me how much fun I had driving myself to learn, try, demo and blog about new tech all the time. Lets hope life does not get in the way.

Tuesday, December 23, 2014

Amazon AWS Elastic Beanstalk, Python, Flask and Sci-Stack Docker

This actually took me longer than I'd like to admit to get working, but in the end the solution is quite neat and simple, so it was probably worth it, and hopefully this could save other people some time.

The Amazon Docker file looks like this: 
AWS Elastic Beanstalk Dockerfile - Github

This installs the contents of the root folder requirements.txt before running your Docker file. So for my application the basic "non-sci" packages could be installed simply enough.

Root Folder: requirements.txt:
Then to install the sci related packages... numpy, scipy, pandas, scikit-learn and nltk. I created another requirements.txt in an aws-post-install folder. This is to be run once the Amazon linux OS has been updated and all the required OS dependencies have been installed.

Post Docker requirements.txt:
My custom docker file, that builds ontop of the Amazon image looked as follows:

Docker File:

Next step is to get my docker image to be used directly so that the Elastic Beanstalk app doesn't have to do all the downloads and installs every time should be simple enough according the AWS you tube channel: https://www.youtube.com/watch?v=pLw6MLqwmew

Tuesday, August 26, 2014

Why Jython when you can microservice with Flask

Over the last little while I have been working on Sibbly it's my little pet project to try summarize, group, filter and target software development information on the web. All 'n all a rather ambitious task, but the worst thing that could happen is that I learn something, so there is really no risk. It is still currently in a very closed beta, only occasionally showing it to fellow work colleagues and getting some input.

After initially starting development for Sibbly on Ubuntu, as I was always planning on deploying on Ubuntu, I had migrated back to windows, and after a couple weeks of work when finally deploying to Ubuntu... Surprise! it obviously did work right off the bat.

The issue I ended up with was, there seems to be a classpath issue between Spring Boot, it's embedded Tomcat instance and Jython. The reason I use Jython is for an awesome library called Pygments.

So after much dismay and checking all the Java alternatives and attempted Pygment ports (jygments, jgments), I started thinking of alternate solutions.
Having recently read: Microservices I decided to look at a way of interacting with Python more indirectly.
This lead me to: Flask
Within a couple minutes thanks to: Awesome Flask Example
I had the following up and running:


What this little bit of Python does is wrap and expose the highlight and guess functionality from Pygments via a RESTful service accepting and producing JSON.

I deploy Sibbly on DigitalOcean
To install Python on my droplet, I followed the process below:

sudo apt-get install python-dev build-essential  
sudo apt-get install zlib1g-dev
sudo apt-get install libssl-dev openssl
sudo apt-get install python-pip
sudo pip install virtualenv
sudo pip install virtualenvwrapper

export WORKON_HOME="$HOME/.virtualenvs"
source /usr/local/bin/virtualenvwrapper.sh

sudo mkdir /opt/python3.4.1
wget http://python.org/ftp/python/3.4.1/Python-3.4.1.tgz
tar xvfz Python-3.4.1.tgz
cd Python-3.4.1
./configure --prefix=/opt/python3.4.1
make  
sudo make install

mkvirtualenv --python /opt/python3.4.1/bin/python3 py-3.4.1

workon py-3.4.1

pip install flask
pip install pygments

Once that was done to run the Flask app:
python app.py & disown

Sunday, August 10, 2014

Upgrading Spring 3.x and Hibernate 3.x to Spring Platform 1.0.1 (Spring + hibernate 4.x)

I recent volunteered to upgrade our newest project to the latest version of Spring Platform. What Spring Platform gives you is dependency & plugin management across the whole Spring framework's set of libraries.

Since we had fallen behind a little the upgrade did raise some funnies. Here are the things I ran into:

Maven:
Our pom files were still referencing:
hibernate.jar 
ehcache.jar 
These artefacts don't exit on the latest version, so replaced those with
hibernate-core.jar  and ehcache-core.jar

We also still use the hibernate tools + maven run plugin to reverse engineer our db object.
This I needed to update to a release candidate:


Hibernate:
The code: "Hibernate.createBlob"... no longer exists

replaced with:

On the HibernateTemplate
return types are now List; not element...So needed to add casts for the lists being returned.

import org.hibernate.classic.Session;
replaced with:
import org.hibernate.Session;

Reverse engineer works a little differently...
Assigns Long to numeric...
Added:

Possible Errors:

  • Caused by: org.hibernate.service.UnknownUnwrapTypeException: Cannot unwrap to requested type [javax.sql.DataSource]
Add a dependency for c3p0:

And configure the settings in the cfg.xml for it:
  • Caused by: java.lang.ClassNotFoundException: org.hibernate.engine.FilterDefinition

Probably still using a reference to hibernate3 factory / bean somewhere, change to hibernate4:
org.springframework.orm.hibernate3.LocalSessionFactoryBean
org.springframework.orm.hibernate3.HibernateTransactionManager

  • Caused by: java.lang.ClassNotFoundException: Could not load requested class : org.hibernate.hql.classic.ClassicQueryTranslatorFactory There is minor change in new APIs, so this can be resolved by replacing property value with:

org.hibernate.hql.internal.classic.ClassicQueryTranslatorFactory.

Spring:
Amazingly some of our application context files still referenced the Spring DTD ... replaced with XSD

In Spring configs added for c3p0:

Spring removed the "local"=: so needed to just change that to "ref"=

Spring HibernateDaoSupport no longer has: "releaseSession(session);", which is a good thing so was forced to update the code to work within a transaction.

Possible Errors:

  • getFlushMode is not valid without active transaction; nested exception is org.hibernate.HibernateException: getFlushMode is not valid without active transaction

Removed from hibernate properties:
     <prop key="hibernate.current_session_context_class">thread</prop>

Supply a custom strategy for the scoping of the "current"Session. See Section 2.5, “Contextual sessions” for more information about the built-in strategies

  • org.springframework.dao.InvalidDataAccessApiUsageException: Write operations are not allowed in read-only mode (FlushMode.MANUAL): Turn your Session into FlushMode.COMMIT/AUTO or remove 'readOnly' marker from transaction definition.

Another option is :
<bean id ="productHibernateTemplate" class="org.springframework.orm.hibernate4.HibernateTemplate">
<property name="sessionFactory" ref="productSessionFactory"/>
<property name="checkWriteOperations" value="false"/>
</bean>

  • java.lang.NoClassDefFoundError: javax/servlet/SessionCookieConfig
Servlet version update:

  • Then deploying on weblogic javassist: $$_javassist_  cannot be cast to javassist.util.proxy.Proxy

The issue here was that there were different versions of javassist being brought into the ear. I all references removed from all our poms, so that the correct version gets pulled in from from Spring/Hibernate...

and then configured weblogic to prefer our version:




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