Lessons learned Spring 3.0 project

Another quick post with some bullet points of lessons learned during my last Spring 3.0 project.
Tools used were:

• Spring 3.0 (3.1.2 when moving to Hibernate 4)
• Spring MVC
• Spring WebFlow 2
• Spring Batch
• Spring Agent Framework
• Hibernate 3.2.6
• Apache CXF
• JBehave (Behavior Driven Development)
• Tiny bit of GXT, which is a Google Web Toolkit extension based on GWT and ExtJS technology. Formally known as Ext GWT, GXT is a Java library for building rich internet applications with the Google Web Toolkit (GWT)
• JBoss jBPM 5.2.0
• JBoss Drools 5.3.1
• Jenkins for CI
• Crucible for code reviews
• Jira for issue tracking en sprint user stories and tasks and progress tracking
• SpringSource Tool Suite 2.9.1 as Eclipse based IDE
• JUnit 4.8
• EasyMock 2.5.2, EasyMockSupport
• Java 6
• Cargo-itest (introduction here) for integration testing
• Tomcat 6
• Oracle SQL Developer (free version)

Besides learning new tools like JBehave an Cargo-itest, below are some things picked up using above tools.

Spring MVC

Had some issues getting REST-like services available, mainly from inexperience, but good to know what's working and what not:

    @GET

    @Path("some-path/?role={roleId}")

    Response getSomeOtherUrlParams(@PathParam(value = "roleId") final String roleId);

    // Unable to call it, because PathParam is not existing (it's not really part of the path)

    @GET

    @Path("some-path2/role/{roleId}")

    Response getSomeOtherUrlParamsNotAsRequest(@PathParam(value = "roleId") final String roleId);

    // Works

    @GET

    @Path("some-path3/")

    Response getSomeOtherUrlParamsAsQueryParam(@QueryParam("role") final String roleId);

    // Works, will have clients of this service (like SoapUI) already generate a ?role= parameter

    @GET

    @Path("some-path4/")

    Response getSomeOtherUrlParamsAsRequestParam(@RequestParam("role") final String roleId);

    // Won't generate a ?role= parameter for clients, the WADL also looks different for this method/parameter

Don't use @FormParam for submitting XML because if the mediatype is text/xml for example, the mapping on the REST method fails because JAXRS expects HTML (default if not specified at the service definition).

So suppose the service is defined as:

    @POST

    @Path("message/{messageCode}/send")

    Response sendMessage(@PathParam(value = "messageCode") final String messageCode, 

                                         @FormParam("moduleName") String moduleName,

                                         @FormParam("userId") String userId, 

                                         final MessageContentsRequest messageContents);

When invoking the above method by POSTing to 

http://localhost:8080/webservice/v1/message/SECRET_MESSAGE_CODE/send 

with as POST body parameters moduleName and userId + the MessageContentsRequest XML, that gives the following error in the log:

2013-01-05 11:24:38,491 WARN  [http-8890-1] JAXRSUtils#processFormParam - An application/x-www-form-urlencoded form request is expected but the request media type is text/xml;charset=UTF-8. Consider removing @FormParam annotations.

2013-01-05 11:24:38,493 WARN  [http-8890-1] WebApplicationExceptionMapper#toResponse - WebApplicationException has been caught : no cause is available

The same error occurs when invoking: ..../send/?moduleName=abc&userId=ttl  (so adding them as POST URL name/value parameters).

So make sure you use in that case:

    @POST

    @Path("message/{messageCode}/send")

    Response sendMessage(@PathParam(value = "messageCode") final String message ode, 

                                         @QueryParam("moduleName") String moduleName,

                                         @QueryParam("userId") String userId, 

                                         final MessageContentsRequest messageContents);

The moduleName and userId can then be passed in via the POST URL name/value parameters.

EasyMock

Use replayAll() and verifyAll() instead of replay(mock) and verify(mock) for each mock seperately. Requires extending EasyMockSupport.

 

SQL Developer

The free SQL Developer can't export clob column values. Nor can it import clob values larger than 4K.

 

Best of this Week Summary 23 August - 29 August 2010

• Basic best practices and optimization techniques for JBoss EAP 4.3 Production Environments.
  


• A tutorial in which you will "create Pingstream, a small notification tool that uses PHP (sorry ;), jQuery and RSS to communicate over the Extensible Messaging and Presence Protocol (XMPP), a set of XML technologies designed to support presence and real-time-communications functionality."
  


• Asynchronouse method invocation with Spring 3.0 tutorial with example code via annotiations. Full task and scheduling reference here.
  


• Good list of REST API anti-patterns.
  


• And another set of anti-patterns, this time for Apache Hadoop. Also includes best practices.
  


• Pretty funky: researchers developed misco, a mobile framework of MapReduce in Python (sorry again :) that can be handled by a server farm/cloud comprised of smartphones (e.g Nokia N95)."
  
  
  

Best of this Week Summary 22 March - 28 March 2010

• Whatever happened to programming? These days it is seems only glueing together a bunch of libraries... Where's the creativity? Well, I think you can now more and more focus on what your app can/should do, instead of re-inventing the wheel all the time. And if you have a real unique idea, you still will have to write those libs too :)
  


• Versioning REST services: "when developers need to create a new endpoint versus just adding data".
  


• A basic comparison between Kindle (JME) & Android Java development.
  

Best of this Week Summary 8 March - 14 March 2010

• How do the Spring 3.0 REST features compare to JAX-RS? Definitely also check the comments.
  


• Wicket IPageStore implementation using Hazelcast ("open source clustering and highly scalable data distribution platform").
  Wicket now powers the mobile sites for Wallmart and Wellsfargo. Main reason for chosing Wicket: "... makes it easy to support multiple different types of devices. The walmart mobile application supports different HTML for three categories of devices (L1: iPhones & challengers, L2: BlackBerries, L3: Plain Old Devices). These three experiences are supported by the same Java code on the server side."
  Great that the implementers have open sourced their components. Especially interesting is the 'wicket-stateless' component, since Wicket at its core is focused on managing stateful behaviour.
  Also great to read is that in Wicket 1.5 support for variable/unknown URLs will be available. In that post you can also read how to do that in Wicket 1.4.
  


• Great post on how MySpace tested their site live with 1 million concurrent virtual users (mixed with live users) using 800 EC2 instances. For example, the setup generated over 77,000 hits per second, not including live traffic. The article also includes 3 lessons learned.
  


• A short article on why eCommerce site Zappos (shoes and apparel) re-architected their site from Perl to a Java EE environment. Main reason for them was to better deal with scaling and demands on high performance. The website serves "millions of users/visitors daily and processes between 60-65.000 purchases every day". Includes some best practices, and a more-or-less infomercial on using Dynatrace as their application performance management solution.
  

Best of this Week Summary 22 February - 28 February 2010

• A real life example on using Spring Integration to migrate content from multiple websites into Hippo CMS, handle errors, measure performance and deal with the fact that content could contain references to other content that is not imported yet.
  


• Summary of this article, which suggests rules for designing standard authentication schemes for REST API’s.
  


• Did you know JavaFX is already used on a big site like the Vancouver Winter Olympics 2010?
  


• Ten useful Java programming tips, maybe there are a few you don't know yet...
  

Best of this Week Summary 14 December - 20 December 2009

• A basic explanation on why to use a service layer in (web) applications.
  


• A description of key concepts in Extreme Transaction Processing (XTP) Patterns: Write-behind Caching. In contrast to write-through caching, the write-behind function batches updates to the back-end database asynchronously within a user configurable interval of time. Also a business use case is described with performance improvement charts. Biggest disadvantage of write-behind is that the database is not always having the latest state available!
  


• This seems like a good Amazon EC2 blog.
  


• A deeper dive into the parts of REST that many people do not understand and therefore do not discuss. These topics include the implications of:
  
  
  • URLs as identifiers
    
  
  
  • Freedom of Form
    
  
  
  • Logically-connected, Late-binding Systems
    
  
  
  • Hypertext as the Engine of State Transfer (HATEOS)
    
  
  

Best of this Week Summary 14 September - 20 September 2009

• Scala is slowly getting some more and more traction lately. Is it a potential long term replacement for Java?
  Interview with Scala creator Martin Odersky where he tells its history, future and why it's so interesting (like combining OO- and functional techniques).
  


• Six valid "takeaways on what most REST adopters can and should do to get the most from their use of this increasingly popular architectural style" summarised by Dion Hinchcliffe.
  


• Article that describes using Benerator, which is a data generator tool that can be used to feed database with pseudo-random test data.
  


• Tip that shows you how to implement composite keys with JPA and Hibernate. Check also the comments here.
  

Best of this Week Summary 24 August - 06 September 2009

• Great introduction to Solr, a search server (and more). The article describes how to get it running, send it some documents to index and how to search those documents in a controlled way.
  


• More details on Google Wave: the draft specification for the Google Wave Federation Protocol and the Java source code for the Google Wave Federation Prototype Server
  


• An extensive comparison of Spring and Seam. And, recently added chapter 5, comparing them with Wicket 1.3.6. Too long for you to read? Then at least read the conclusion :)
  Talking about Wicket, here are some
  experiences written down on migrating an existing Wicket application to the new 1.4 version.
  


• This article provides a short overview on the basics of RESTful HTTP and discusses typical issues that developers face when they design RESTful HTTP applications. It shows how to apply the REST architecture style in practice. It describes commonly used approaches to name URIs, discusses how to interact with resources through the Uniform interface, when to use PUT or POST and how to support non-CRUD operations.
  Related to that, here's 8 great tips/lessons learned for creating an API.
  

Best of this Week Summary 8 June - 14 June 2009

• A whole bunch of AJAX best practices in this PDF presentation from JavaTech 2008, Pune - India.
  


• Another article with more details and explanation on WOA by Dion HinchCliffe. Web Oriented Architecture: it's a set of best practices for designing Web applications in which REST is the foundational architectural style. Below the stack:
  
  


• A little bit off-track, but maybe very appropriate for you: Top 10 Reasons Why Employees Leave in IT.
  


• Yup, Sun (Oracle) now also has its app store: the Java Store. Still in private beta.
  

Best of this Week Summary 18 May - 24 May 2009

• Tutorial in which you learn to build an SOA application which is listening for incidents coming from web service or files. According to the origin, the content (= incidents) are transformed into their corresponding objects using for the CSV file, a new Camel component : camel-bindy and for the Web Service camel-cxf component. Each message transformed is placed in a queue handled by ActiveMQ engine. All the messages (containing the objects) are next processed by a Bean service who will (with the help of injection of dependency provided by Spring) save the incidents in a DB using Spring and Hibernate frameworks.
  A small Apache Wicket web application running in Jetty Web server provide to the users a screen to consult the incidents created.
  


• This feed is handy to follow to see what's getting more mainstream traction and technology trends. E.g Thought Leadership: Technology Brief May 2009.
  


• All of Dion Hinchcliffe web 2.0 diagrams at one place.
  


• JSON REST webservices best practices described by the Feedly team. A related more general pros & cons of REST are described in this article.
  


• WiQuery aims to integrate the JavaScript frameworks jQuery and jQuery UI with Wicket, a Java framework providing a real way to create web applications with an OO approach. Other integrations like with MooTools, Dojo and Scriptaculous with Prototype can be found here. BTW, a comparison between MooTools and jQuery can be found here.
  


• The distinction between a spring singleton and a java singleton explained.
  

Best of this Week Summary 02 March - 08 March 2009

• The UI teamlead of Google's Chrome browser explained at a presentation why they decided to build Chrome. Basically because all the existing browsers suck :-)
  


• A memory and performance comparison between Seam+JSF and Wicket. Wicket wins both. Also check the comments for useful feedback. Possible reasons for the differences in performance are: JSF performs much more expression evaluation and the JSF lifecycle is much more complex.
  


• The Open Group has released version 9 of The Open Group Architecture Framework (TOGAF) for enterprise architectures. TOGAF is often combined with ArchiMate for modelling. Most important addition to version 8 is the content framework which describes what an architecture exists of. Here's some feedback from actual users on TOGAF 9.
  


• Talking about standards, the OASIS committee has updated a bunch of webservices specifications/standards.
  


• A nice post on how to write a Javascript client that sites can use to access your REST API. Biggest challenges that had to be solved were:
  

  1. Browser same-origin restrictions on XMLHttpRequests (XHRs) and inter-window/frame access
     
  
  
  2. The lack of wide browser support for HTML 5-style message passing between windows.

• Java Enterprise Edition 6 (Java EE 6) Specification (JSR 316) is getting there...
  

Best of this Week Summary 26 January - 01 February 2009

• Part 1 of a series on how to represent XML schema types taking into account the mismatch between XML and the datatypes of a programming language.
  


• Nice non-techie explanation of what OAuth is. Plaxo and Google are now trying out a combination of OpenID for federated authentication and OAuth for the authorization process, and including the Google Contacts API in the workflow. Thus, more and more towards the Open Stack.
  


• A great series of SOA Patterns by Thomas Erl. This is the first one, a Service Façade.
  


• An interesting opensource effort to make consuming REST services more object oriented and Rails ActiveResource like with Rapa. "Rapa uses the tried and tested Jakarta Commons HttpClient and JAXB."
  


• And as the last item this week, get ready to test your websites with Internet Explorer 8, RC1 can be downloaded now and should be nearly identical to the final version.
  

Best of this Week Summary 12 January - 19 January 2009

• A couple of tips on Building Super-Scalable Web Systems with REST. All the client wanted was a getLocalWeather webservice for their 10M+ users website. At first it was implemented with a regular (MS WCF) webserivce, but for scalability they switched to resource-based REST.
  


• How to get rid of the Javascript splash screen in Oracle ADF Faces 11g Rich Client, and how to reduce the initial Javascript download size on the first page in an ADF application. Described is a currently undocumented feature that sets Context Parameters in web.xml, performing compression and only downloading the Javascript that is needed on the current page. Amazing for such an essential element to be an undocumented feature, because the default complete ADF RC Javascript libs can be up to 2M in size.
  


• A post with a summary of points on the question how secure cloud computing is. Quite related to my own recent tutorial on setting up an Amazon AMI with Java and MySQL on EBS using the AWS Management Console.
  


• Interesting white paper which "presents an overview of the architecture and configuration of the Sun Blogs web site, a blogging service dedicated to Sun employees worldwide. It also provides usage statistics and information about the system administrator's experience managing one of the busiest externally facing Web 2.0 site deployments at Sun".
  
  "Blogs.sun.com is powered by Sun Java™ System Web Server 7.0 Update 2 (hereafter, Web Server) running on a pair of Sun Fire™ T2000 servers with UltraSPARC® T2 processors. The site also uses a custom version of the open source blogging server Apache Roller Weblogger Version 4.0.0.12 (http://rollerweblogger.org/project/), MySQL™ database server, and Memcached. The service is integrated with Sun's secure single sign-on identity system backed by a worldwide employee LDAP directory for authentication and authorization."
  

Best of this Week Summary 29 December - 11 January 2009

• Interesting comparison whether and when to use SOAP or REST.
  


• OpenSocial now has Java, PHP, Ruby and Python client libraries available.
  


• A few weeks ago, PKI which uses MD5 as cryptographic hash function, has now officially been broken at the hackers convention Chaos Communication Congress 2008. Six Certificate Authorities still give out MD5-signed certificates as mentioned in the article. Since 2004 it is already known that MD5-collisions can be created for different data. Therefore, certificates should be issued with at least SHA-1 encryption. Here's a summary of what an MD5 collision is and what Mozilla and Microsoft issued as advisories. Additionally some (other) SSL issues are described.
  


• Nice summary of lessons learned during a project using GWT, Axis and JPA. Some more comments here.
  


• Paper by Kate McKinley (a researcher at iSec Partners, a San Francisco security firm) on the privacy protection mechanisms of FireFox, Chrome, IE and Safari. Conclusion: "We find current browsers are unable to extend tracking protection to third party plug-ins such as Google Gears and Adobe Flash. Some of these require no user prompting under common configurations and even expose tracking data saved with one browser sites visited by a different browser. [...] Safari on Windows fared the worst of all in these tests with respect to private browsing, and did not clear any data at all, either before entering or after exiting the private mode. On OS X, Safari’s behavior was quirky; in no case was the HTML 5 database storage cleared before or after private browsing.".
  

Best of this Week Summary 16 December - 28 December 2008

• Great insight on Second Life's architecture. For example: "A physical server (1 CPU) is responsible for about 16 acres of land and it is connected to neighboring ones which are each responsible for another 16 acres. The server is responsible for the objects existing in its area, the scripts running, the users logged in and standing in its area". Presentation is one hour in total.
  


• There's more to REST than meets the eye. And many REST APIs are not really as REST as Roy Fielding defines it. Media type design is an important item that was not in his original REST dissertation. Some interpretation of what Roy actually means can be found here.
  


• JanRain (known for their OpenID libraries) have created a nice widget named RPX that allows you to integrate authentication within your existing site in an easy and user-intuitive way. I really like the clear, easy and non-intrusive way the possibilities are shown. For real novice users the redirecting to and from the authenticating sites might still be a little bit confusing though. Supported protocols are: OpenID 1.x/2.0, Facebook Connect, MySpaceID and Google. Below is a screenshot of what the registration part looks like:
  
  A couple of example sites where this is already implemented can be found here. And some more on the possibilities here.
  Note that from the technical overview you can see that the RPX server sits in between. That is the only disadvantage of this solution: that you are dependent on an intermediate server.
  


• The W3 Consortium has released a webpage mobile-friendliness checker. The tests it performs can be found at the mobileOK Basic Tests 1.0 specification. Other validators you might know from them are the feed validator, XML Schema Validator, CSS validator or Markup validator. Running these very succesful services without any advertising is costing a lot of money. Therefore you can now donate here for support. If you compute how much time those validators have saved you, donating any small percentage of that will already help W3C keep these validators running.
  

Best of this Week Summary 17 November - 30 November 2008

• Interesting recent long discussion (with a bit of framework flame-war in between) and tips on when to pick what web client framework. Tapestry, Wicket, Stripes, GWT, Flex seem to jump out.
  


• Interesting Javascript optimizer: Razor Optimizer. It dynamically analyzes the runtime profile information, trying to load each Javascript function only when needed, potentially creating 60-90% savings. It does require a client and server component. The question is: are you prepared to take a (small?) risk that your Javascript is dynamically modified?
  


• Good article that explains why Scrum often fails as implementation of Agile. Lots of times Scrum is only seen as fast Sprints and Scrums. But: "Don't leave out the 'regular' agile good engineering practices". Check also the comments for good tips.
  


• A good introduction to RESTful webservices.
  


• Great, soapUI 2.5 now also suppports testing RESTful webservices. It includes testing JSON output.
  

Best of this Week Summary 04 November - 16 November 2008

• Part 2 in a series on server load architectures: application-level load balancing, including client-stickiness.
  


• How to write maintainable CSS; a presentation by Natalie Downe.
  


• ProgrammableWeb is tracking APIs and has now reached the 1000 milestone. In the pie charts you can see the top 15 categories and which protocols they use: 63% of the APIs uses REST! 22% SOAP. The protocols diagram is shown below:
  
  


• Here's some more details on why Google forked OpenID. See my related post of two weeks ago.
  


• A presentation with the current state (it's growing big time!) of OpenSocial shown at OpenSocial's first birthday at MySpace's headquarters.
  


• I'm currently trying out Wicket with Spring and Hibernate, using AppFuse Light as a starting point. In case you're looking for an introduction to Wicket, check out this one that has been around for a while, and this new one that's been posted this week.
  

Best of this Week Summary 20 October - 26 October 2008

• Good tips on how to write clean code.
  


• A high level comparison of JAX-RS (Java API for RESTful Web Services) four implementations: CXF (Apache), Jersey (Sun), RESTEasy (JBoss), and Restlet (open source). Here's how they integrate with Spring.
  


• Four approaches to get to a canonical message model (CMM) in an ESB. Check also the previous two articles in this series.
  

Best of this Week Summary 7 July - 13 July 2008

• Bjarne Stroustrup in an interview describing what every programmer and software engineer should know about C++.
  


• Browser memory performance comparison between Safari 3.1, Firefox 3.0, Flock 1.2, Opera 9.5 and IE 8.0 B1. Conclusion: Firefox 3 beats them all in memory efficoency.
  


• Definite interesting read this white paper from Kent Beck "Tools for Agility". On an invitation basis from Microsoft, he wrote "thoughts on the relationship between tools and agile software development. He looks at how tools have evolved in aiding software flow, efficient transition and team transparency". It includes what makes agile development different and difficult from other development-cycle approaches. For example the tools should support: even shorter development cycles, even more automated testing, much more transition between activities, transparency and real time collaboration, .
  


• Great list of eight REST anti-patterns.
  

Best of this Week Summary 05 May - 11 May 2008

• Free IBM Redbook with SOA and webservices patterns.
  


• Eclipse plugin Monkey to automate tasks like Java projects that don't have a Checkstyle configuration defined or find commented out code and defines tasks for them (TODO/FIXME),
  


• The potential doubts regarding REST in practice, mainly for designers/developers with a SOAP/WSDL background.
  


• An overview of Agile anti-patterns, like "keep refactoring for later" and "let's fix the testcase later, we'll uncomment it for now".