Category Archives: Java/Java EE

Creating a UML diagram with Eclipse Papyrus

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Yesterday, I upgraded my Eclipse to Kepler. I needed to create a UML class diagram and decided to try out Papyrus – an Eclipse incubator project.  It wasn’t as straightforward as I expected so blogging about what to do and what not to do.  Class_Diagram

I think this project needs more documentation (and a few more features) before using it seriously.  Luckily, my diagram was trivial.  In fact, it was so trivial, I decided to switch to PowerPoint (or in my clas – Open Office Drawing)

Regardless, here’s what I learned before giving up on it.

Creating a diagram

  1. File > New > Papyrus Project
  2. Enter project name
  3. Click NEXT (Do not click Finish.  I was unable to use papyrus > new diagram > create new class diagram when I didn’t create one right away)
  4. UML
  5. Click next
  6. Enter diagram name and click “UML Class Diagram”
  7. Click finish

Adding a class

  1. Switch to the Papyrus Perspective
  2. Drag a “Class” node from the palette view at right
  3. Click the “Class 1” name once and then type the name of your class.  (Do not double click the class box as it opens a hyberlink view.  Do not click the class box and expect to type in it
  4. Drag an ‘Operation” node from the palette at right onto your class
  5. Click “Operation 1” and type the name of your method (Do not add an operation to the model explorer view at left as it will not show up in the diagram)

Preferences

In the Eclipse preferences, you can set a number of view preferences.  They are extremely granular.  For example, I wanted to hide the fourth “section” of the UML diagram showing just class name, attributes and operations.  To do this, I had to:

  1. Preferences > Papyrus > Diagrams > PapyrusUMLClassDiagram > Class Node
  2. Uncheck “show compartment” in NestedClassifierComponent section
  3. Preferences > Papyrus > Diagrams > PapyrusUMLClassDiagram > Interface Node
  4. Uncheck “show compartment” in NestedClassifierComponent section
  5. Delete my diagram and create a new one as I could not figure out how to get preferences to take effect on an existing diagram.

What still puzzles me

There has to be a way to refresh the graphical view to sync with the model explorer and update based on workspace preferences.

eclipse kepler (4.3) on a mac

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Getting started

When going to the Eclipse site, I was greeted with a cool book looking page about Kepler.  Who Kepler is, what’s new, the link to download, etc.  kepler-book

Choosing a package

Eclipse has a nice chart comparing the features in each edition.  I’m excited to see git and maven got promoted to the Java EE edition.  In fact the Java EE edition is *almost* a superset of the Java edition now.  The download is 50MB bigger than last time.  And since Verizon wired the basement for FIOS but not any individual apartments yet, this means 30-45 minute download.  Now that I have the file eclipse-jee-kepler-R-macosx-cocoa-x86_64.tar, I can start.

Installing on A Mac was a small adventure

I did the usual of untarring and copying the eclipse folder into Applications.  I got an error: “Eclipse” is damaged and can’t be opened.  You should move it to the Trash.

I found a command here to get Gatekeeper to allow it:  xattr -d com.apple.quarantine /Applications/eclipse/Eclipse.app

Then I got: Failed to load the JNI shared library /Library/java/JavaVirtualMachines/1.7.0.jdk/Contents/Home/bin/../jre/lib/client/libjvm.dylib

I was on Java 7 update 17.  I updated to update 25, but that didn’t help.  I then tried using a launch startup script per the bug report.  Note that I needed to change two bolded lines to point to my install location.

#!/bin/bash
/Library/Java/JavaVirtualMachines/1.7.0.jdk/Contents/Home/jre/bin/java \
-Djava.library.path=<strong>/Applications/eclipse/plugins/org.eclipse.equinox.launcher.cocoa.macosx.x86_64_1.1.200.v20130521-0416/eclipse_1507.so</strong> \
-Xms512m \
-Xmx2048m \
-Xdock:icon=../Resources/Eclipse.icns \
-XstartOnFirstThread \
-Dorg.eclipse.swt.internal.carbon.smallFonts \
-XX:MaxPermSize=256m \
-jar /Applications/eclipse/plugins/org.eclipse.equinox.launcher_1.3.0.v20130327-1440.jar \
-os macosx \
-ws cocoa \
-arch x86_64 \
-showsplash \
-name Eclipse \
--launcher.appendVmargs \
-debug

It sounds like this will be fixed in Kepler SR  1.  In the meantime I renamed my script to end in .command so I can open it via the applications finder window (nice tip)

First Impressions

Since some of the plugins I was using are now built in and others I don’t use anymore (that I installed over the past year), I decided not to import my plugins from a previous installation and start anew.  It’s easy enough to install from the marketplace.

The significant plugins I use:

Plugin Purpose
Mongrel Tomcat integration supporting Tomcat 7.  (The version of Sysdeo I was using seems to have had that too but at least Mongrel looks more active.) Used the Sysdeo source code and forked it since Sysdeo isn’t getting updates anymore.
Ecl Emma Code coverage
PMD and FindBugs Static analysis
Subversive To access Subversion repositories
Groovy/Grails Tool Suite Groovy project/editor and console
Eclipse Memory Analyzer For finding memory leaks – must use update site rather than marketplace
Freemarker IDE Freemarker syntax highlighting and macro assistance.  Note that it is listed under the JBoss Tool Project.
Papyrus UML editor – under install new software > kepler > papyrus  (I don’t recommend Papyrus at this time.)
Python Python plugin/perspective

What excites me

  1. Mylyn connector improvements (for code review)
  2. Remove type arguments after content assist – this happened just often enjoy to be annoying
  3. IDE support for JUnit Assumptions

What frustrates me

  1. The mess about Mac support for Kepler.  It’s annoying launching from the command line (or even a command).

blogging from reza rahman’s jee 7 talk

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This month’s NY JavaSig was chock full of information about JEE 7.  It was nice seeing it before Oracle’s launch webcast.  And at a more convenient time as well!  Given that Reza Rahman works for Oracle, we got the standard Oracle disclaimer that anything can change in the next two weeks.  But we all know they don’t have time to change much so 99.9% of this should be true.  [comments in brackets are my opinions; not Reza’s or Oracle’s]
High level JEE 7 changes
  • JMS 2. Batch. Transactions. Concurrency, interceptor, web socket java api, json java api
  • El 3, jms 2′ jax-rs 2.
  • Rest like EJB are minor releases. Ejb 3.2 (interestingly CMP is from J2EE 1.3)
  • Add to web profile: jax-rs 2
  • Deprecate jax rpc, cmp, cmp, jsr 88 – no known tools to get off bmp/cmp
  • Themes are productivity and html 5, core foundational apis
Jms 2
  • 8 year old api. Needed an overhall
  • Change api to use  DI
  • Delivery delay, async send, delivery count, now standard rather than optional, mdb alignment
  • Now you just inject JMSContext and Queue – a  new Object. Reduces code from a slide to a few lines.
  • Uses default JMSContext connection factory unless specify otherwise
  • Context has createProducer() and createConsumer(). Uses builder pattern so can chain/use one liners to configure
  • New API uses runtime exceptions
  • Added JMSConnectionFactoryDefinition and JMSDestinationDefinition annotations so can configure in code instead of vendor specific descriptor. Can still use xml instead of annotations
  • MDBs have new @ActivationConfigProperty
  • Spring will be supporting JMS 2 in their apis. Will need new JMS apis as well from third party libraries.
Websockets
  • Stateful protocol. Bidirectional async communication. Good for gaming, online stock tickers, etc
  • Uses HTTO as handshake between client and server
  • Part of HTML 5. Hope people will be using within 3-5 years.
  • Very high level API
  • Supports both declarative and progamatic programming. Most people should be dealiling with declarative api.  The programmatic one is meant for third party api developers
  • Abstracts keep alive setting
  • Weakness in websocket spec: can use up all sockets on a machine
  • Keep alive packets sent about every 5 minutes (vs 30 seconds normally). If your router times out after a minute, you’ll need to reconfigure. No session replication yet. If server goes down, you lose it
  • Server side code – POJO with annotaton for serverendpoint(url)’ onopen and onclose. Onopen and onclose callbacks get passed a session. Also callbacks for onmessage and onerror.  Use session.getRemote.  To get handle to remote endpoint and call sendXXX. It is NOT an HttpSession  because you are not in http level of abstraction
  • Client – JavaScript has an api for websocket.  Use this 90 peercent of the time
Json
[feels like java util logging.  late to the party and not as good as open source libraries]
  • Have jsonp – Like xmlp?
  • Will have jsonb in future –  Like xmlb. Eclipselink has two implementations now. Moxi and eclipse link json binding. The later one is likely to be closest to the standard.
  • No safe bet. Use what exists now and change later
To use
  • JsonArray  array = Json.createArrayBuilder(). Can add primatives and objects
  • To read: parser().iterator and parser,getString()
  • iterator,nextO will return START_OBJECT, KEY_NA ME, etc in addition to the real values.  [ugly – reminds me of the early days of DOM]
JAX-RS 2
[Lost what i typed because after deleting text undo deleted still more text. I think i remembered it all to retype]
  • Jersey is an implementation as is RESTEasy
  • Jax-rs was was introduced in jee 6
  • Hypermedia support – using hyperlinks in rest, like for lazy loading
  • Cient api, message filter, entity interceptor, asnc processing for high throughput, content negotiation (queues used to apply weight to client)
  • Client api: ClientBuilder.newClient() and client.target(url, params, …  )
  • For filter implement ContainerRequestFilter
JPA 2.1
  • Schema generation – every provider supports already.  This adds a standard format. Can create database and/or ddl,   Showed examole with index names in Java and said “no other way to do it” [yuck – this is why you should separate your DDL and not store it in only in Java.  You are going to need that standalone DDL later anyway for laters so why not put the index there.]
  • Stored procedure support – people want it, all providers have it already so gave in and put it in in ORM spec.  Looks like namedqueries. @NamedStoredProcedureQuery
  • Unsynchronized persistence contexts – can join when  ready to rejoin context
  • Entity convertors – edge case solution for odd format in database field but dont want in java objects
  • Fixes/enhancement
Jta 1.2
  • Old api that needed an update. Lots of fixes and two new features
  • Declarative transactions outside EJB – any CDI object supported now. @Transactional. Default is rollback for runtime exception and ignore checked exception
  • @TransactionScoped – new CDI scope. JMSContext uses this scope
Jsf 2.2
  • Html 5 support – pass thru html 5 components. Use normal inout type=color and then jsf:value and el expression as attribute. That way not limited to jsf component libraries. Similary jsf:id, jsf:validate, jsf:renderer
  • @Flowscoped – alternative to conversation scope. Conversation was suited to wizards. Flow scoped keeps certain objects active for different parts of the app. [Code looks like a state diagram in java code – long]
  • @ViewScoped for CDI
  • Deprecated JSF managed beans. Use CDI instead
  • File upload component – couldn’t add until now because JSF was being backward compatible with 2 versions of servlet apis
  • View actions – can trigger an action when land on page rather than wait for user to click on something
  • Multi templating – templates can have parents
  • Security
Batch applications
  • Concepts. JobRepository, Job,JobOperator, Step, ItemReader, ItemProcessor, ItemWriter ( map reduce pattern with readerprocess, write)
  • The java community doesnt generally get into batch processing. Financial community is different. Hadoop and analytics starting to bring batch to wider audience
  • To code use named annotation and implement Itemreader, ItemProcessor, ItemWriter
  • Write XML for step to chunk it and send to reader, processor and writer. Methods. ReadItem, processItems, writeitems
  • IBM websphere compute grid  called out for batch multi threading on different machines.
  • IBM most active and spring second most active contributor to batch spec. Presumably that means Spring is interesting in supporting
Bean validation 1.1
  • Added method level constraints.  Useful in REST. Method param and return type constraints.  Used to only have property level
  • Bean validation artifacts injectable
Concurrency utilities for JEE
  • Builds on JSE Executor Service
  • Thread pool aware
  • Relatively low level API
  • Don’t expect a lot of people to use.  Meant for third parties running on JEE so can share app server thread pool
  • Inject ManagedExecutorService annotation. Submit your task to executor
El. 3
  • Lambda expressions, collections support, operator support
  • EJB 3.2 truncating BMP/CMP
  • Servlet api – non blocking IO
  • Ordering of interceptors
Jee 8 
  • jsonB. – probably before JEE 8
  • Jcache – available as drop in jar before. Just missed JEE 7 cutoff
  • Lots more stuff
Tomcat
  • Base Tomcat planning on supporting JSR 356 (web sockets), maybe concurrency utilities
  • TomEE – apache project taking plain tomcat and brining up to JEE web profile level. It is certified against web profile