Vaadin add-on Timeline vs Vaadin Charts add-on comparison

Introduction

For a recent project I had to evaluate the Vaadin Charts and Timeline add-ons for their capabilities.

Setup
- Vaadin 7.0.1
- Vaadin Charts 1.0.0
- Vaadin Timeline which is included in Vaadin Charts since Vaadin 7.0

Requirements
- Be able to see data for 90 days, and the same data but then per week (same graph, just other view).
- Be able to click on a bar and perform some action like retrieving other data based on the selected bar.
- Customizable three code coloring stacked bars.
- Display more details when hovering over a bar.


Comparison

Timeline

This type of graph is very flexible and elaborate in the ways it can display data. It has a "selection bar" below the actual graph so you can determine the values being displayed in the graph above it. See below for a screenshot:

You can try it out yourself in an online demo here and here.

Pros

- The graph is scrollable thus no worries about the bars/lines getting too close to each-other.
- You can zoom in and out, also with your mouse.
- Different charts (graph modes) provided by default, changeable in one click: line, bar and scatter.
- A quick zoom per period (1d, 5d, 1w, 5m etc).

Cons

- Can't attach any action to clicking on a bar. What you can do is react on the area selected with the selection bar, so a work-around might be to have the user select exactly one bar to mimic a kind of "clicking" on that bar. And then take the appropriate action.
- You can only show days on the x-axis it seems. You can't show a bar per week for example (thus one bar representing 1 week). A work-around might be to create your own Zoom period for 1 week, which is quite easy to do.
- Currently as of this writing there are at least two bugs regarding hovering: the timeline moves down a few pixels when hovering for the first time, and the stacked bars have a hovering problem.

Untested

- Can you also add an hover-over tooltip to the bars?


Chart
This type of graph does not have the fancy zooming possibilities, but has more possibilities regarding customization and reacting to events. See below screenshot for an example:

You can try it out yourself here.

Pros

- The bars are clickable and that event can be handled, indicating the x and y of the item clicked.
- The graph is more customizable; for example the numbers in the bars can be removed.
- Different values (like week number) on the x-axis is probably possible (still out for investigating).
- All data is always visible in the current view.
- Customizable hover-over tooltip.
- Does not have the two (smaller) timeline bugs.

Cons

- No horizontal scrollbar or similar, thus for example showing 90 days looks quite "cramped", see the above screenshot. When making the browser smaller, day numbers start to overlap. Do-able, but not optimal. A horizontal scrollbar would be great!
- No space for showing a full date at the bottom. As a work-around the actual date could be added to the tooltip when hovering over a bar (in the screenshot it only says 26).
- No zooming.
- No out-of-the-box other graph modes (i.e like in the Timeline those are provided with it always).


Conclusion

For the project we chose the chart because it is a bit more customizable and the ability to click on a bar and do something with that event was most important requirement.

Best of this Week Summary 02 November - 08 November 2009

• A summary of an interview with Erich Gamma, Richard Helm, and Ralph Johnson, three of the Gang of Four who wrote Design Patterns: Elements of Reusable Object-Oriented Software 15 years ago. The full interview here.
  


• Five web frameworks comparison: Shale, Struts, Wicket, WebWork, Rails, JBossSeam, MyFaces and Spring.
  


• Jeff Dean (Google Fellow) on large-scale computing (PDF) during Ladis 2009. Interesting numbers regarding reliability and availability for hardware, like 1-5% of your disks will die. And even if you got very reliable servers with MTBF of 30 years, if you have 10000 of those, that means see one fail each day! And: "a web search touches 50+ separate services, 1000s machines". Some more of these quotes:
  
  
  
  • "Better to give users limited functionality than an error page"
    
  
  
  • "Ensure your design works if scale changes by 10X or 20X but the right solution for X often not optimal for 100X"
    
  
  
  • Monitoring: "If your system is slow or misbehaving, can you figure out why?"
    
  
  
  • "Future scale: ~106 to 107 machines, ~1013 directories, ~1018 bytes of storage, spread at 100s to 1000s of locations around the world, ~109 client machines"
    
  
  Other subjects touched: MapReduce and BigTable.
  
  
• Blogpost that briefly touches a few types of complexity encountered in large software (web) projects.
  

Best of this Week Summary 21 September - 27 September 2009

• Always feeling a bit less up-to-date when using RSS/Atom feeds? Well, convince your RSS/Atom provider to implement the PubSubHubBub protocol: it provides a callback-hook, which when registered to as feed subscriber, causes an immediate update (ping) to the subscriber (instead of waiting for the next RSS/Atom feed request).
  Or will rssCloud be the winner of this realtime RSS extension? Here's the basic (simpler) flow of rssCloud:
  
  
  Differences between the two are described here (including some issues) and here. A real old-fashioned flame-war has even started between the creators of the two protocols.
  And a good comparison which explains quite well why PuSH is the better choice of the two. Note that both protocols seem to be server-to-server only! (e.g think when you're behind a firewall or NAT...)
  See this article for an explanation of the PuSH flow of notifications/information in below's diagram:
  
  
  Update: PubSubHubbub explained by co-creator Brett Slatkin (an engineer at Google).
  
  
• Want to get to know Hadoop? In short "Hadoop allows you to write and run your application in a distributed manner and process large amounts of data with it. It consists out of a MapReduce implementation and a distributed file system." Check the rest of this introduction for more details.
  


• Five Java anti-patterns to prevent (out-of) memory problems.
  


• Three Best and three worst practices in BPM and SOA.
  


• "Tom Killalea, Vice President of technology with responsibility for infrastructure and distributed systems engineering at Amazon.com wrote an article on ACM queue on building scalable web services. He outlines guiding principles to building scalable web services with a lot of real-world examples, the core theme of which is “build only what you need”."
  

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 20 July - 26 July 2009

• Handy tip for creating testdata for your testclasses via "factory" helper classes, to prevent copying the construction of this testdata again and again.
  There's also a database version.
  


• A comparison of the following opensource search engines: Lucene, Zettair, Indri, Sphinx, and Xapian.
  


• Best practices for using the Java Native Interface.
  


• A great "free PDF White Paper from OASIS, OMG, and The Open Group was written to help the SOA community at large to navigate the myriad of overlapping technical products produced by these organizations with specific emphasis on the “A” in SOA; i.e., Architecture. The docment explains and positions architectural standards for SOA reference models and ontologies, reference architectures, maturity models, SOA modeling profiles, and open standards work related to the topic of SOA governance. It also outlines the agreement on core SOA and SOA governance concepts."
  


• How bad can one GOTO statement really be? ;)
  
  
  

Best of this Week Summary 13 July - 19 July 2009

• Pretty basic SOAP monitor (proxy) that allows you to edit SOAP messages before sending them on. Does not support a proxy (yet).
  


• IBM recently released Milepost GCC (website has styling from 1998 ;), a "compiler which analyses the software and determines which code optimizations will be most effective during compilation using machine learning techniques. Experiments carried out with the compiler achieved an average 18% performance improvement. The compiler is expected to significantly reduce time-to-market of new software, because lengthy manual optimization can now be carried out by the compiler." Related to that is also the Collective Tuning wiki, dedicated to developing self-tuning computing systems.
  


• ZeroTurnaround "has released the results of their "Java EE Containers - Heaven or Hell" survey. Using responses from 700 respondents, they cover topics such as: containers most often used on large projects, fastest container, redeploy times and annual costs of redeployment in a series of charts and calculations. Both the charts and raw data are made available for your own analysis."
  


• Looking for petabyte and beyond scale storage? The opensource project Ceph might be an option: it is a distributed network file system designed to provide excellent performance, reliability, and scalability.
  


• Several basic and advanced JPA implementation patterns can be found here.
  

Best of this Week Summary 04 May - 10 May 2009

• Reference to an AJAX framework analysis/comparison result by Matt Raible (for example known for his framework of frameworks: AppFuse). Compared were Dojo, Ext JS, GWT, and YUI. Check also the comments.
  


• Beginners level host and Java performance tuning concepts.
  


• Handy PHP profiler and debugging tool/library. Helps you with logging, memory usage, double includes, page execution time and database activity monitoring.
  


• Nice presentation on scalable web architectures from Cal Henderson, (ex) Flicker architect. Including horizontal vs vertical, architecture, sessions, load balancing, queuing, relational data, caching, H(ighly) A(vailable) data, federation, serving and storing files, CDN, real-world examples.
  


• SpringSource has created Roo, a sophisticated round-tripping code generator that should make it quicker and easier to create and evolve Spring applications.
  


• Funny: how to measure code quality: WTFs/minute :)
  
  
  Via.
  


• You as a developer can now go social on IBM's myDeveloperWorks, a social network spun off of developerWorks.
  


• An introduction on how one could formalize a SOA using WS-CDL, including a few real-world insurance based uses.
  


• Yahoo has just released a major update for their innovative YQL. "The Yahoo! Query Language lets you query, filter, and join data across any web data source or service on the web. Using our YQL web service, apps run faster with fewer lines of code and a smaller network footprint. YQL uses a SQL-like language because it is a familiar and intuitive method for developers to access data. YQL treats the entire web as a source of table data, enabling developers to select * from Internet." The update adds "Execute", with which "developers now have full control of how the data is fetched into YQL and how it’s presented back to the user. With Open Data Tables, developers can build tables that manipulate, change, and sign the URLs to access almost any protected content, allowing YQL access and combining data across a variety of different authenticated services such as Netflix or Twitter. Developers can call multiple services and data sources within Execute to join and mashup data however they desire, letting Yahoo! do the work rather than their applications. Data can be tweaked and manipulated into an optimal format for applications to consume." Another example of what is possible can be found here. Check also this article for more explanations.
  

Best of this Week Summary 09 March - 15 March 2009

• A table-based quick review of the following RIA frameworks: GWT 1.5, Laszlo 4.2, pure Javascript and Flex 3.2.
  


• A short introduction on how ActionScript 3 differs (and not) from Java.
  


• A wiki constructed with over four dozen architects: 97 things every software architect should know. Also now available as a book. It includes advice such as:
  
  
  • Don't Put Your Resume Ahead of the Requirements (Nitin Borwankar)
    
  
  
  • Chances Are, Your Biggest Problem Isn't Technical (Mark Ramm)
    
  
  
  • Communication Is King; Clarity and Leadership, Its Humble Servants (Mark Richards)
    
  
  
  • Simplicity Before Generality, Use Before Reuse (Kevlin Henney)
    
  
  
  • For the End User, the Interface Is the System (Vinayak Hegde)
    
  
  
  • It's Never Too Early to Think About Performance (Rebecca Parsons)
    
  
  


• An introduction to Object Oriented CSS.
  


• Sample chapter from Thomas Erl's latest SOA Design Patterns book, and an interview with him. He "talks about the main benefits of having a pattern catalog, SOA and Web services, the current state of SOA, the difference between SOA and service orientation, and the role of patterns in SOA adoption".
  


• A series of five articles on setting up a Java Wicket project and implementing a frontend with it.
  


• Handy piece of (alpha) software to test IE8 RC1, IE7, IE6 and IE5.5 on Vista and XP. Note that it looks like Microsoft is releasing IE8 this coming week, so get ready...
  

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 02 February - 08 February 2009

• In SOA lessons learned for Web 2.0 "two experienced SOA architects look at the new world of Web 2.0 technologies with a critical eye and present five best practices that can help you be more successful in adopting Ajax, REST, and other Web 2.0 technologies as part of your SOA."
  


• A quick comparison between Echo2 and GWT. Both enable you to create a rich internet application with only Java using a component-based approach. Wicket is also component based, but requires still to work with HTML; not necessarily a negative thing! For example, how will you split the work between the user interface designer and developers with Echo2 and GWT?
  


• A nice extensive summary of Model Driven Development misperceptions and challenges. Five challenges and five misconceptions in total.
  


• A whitepaper named "Centralized Service-Oriented Architectures without ESB" which shows how to create service-oriented architecture in a Google-like way, that is services around huge data repository, but without ESB. It is based on experience of the writers in data warehouses, Wiki and telecommunication systems. Thus, proposed is not really an ESB, but an architecture that's more like a centralised repository with distributed caching. Of course this comes with its own set of pros and cons, as mentioned in the whitepaper.
  

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 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 29 September - 05 October 2008

• Check the elaborate 95 slides comparison of Javascript libraries at the bottom of this post. It's a presentation by John Resig, Mr JQuery. The presentation is very objective. Compared are: Prototype, jQuery, Yahoo UI, Dojo and Mootools. Another short comparison of 14 RIA/Ajax/Javascript frameworks shows jQuery as the winner, as seen by the User eXperience reviewer. Great news for jQuery this week anyway: both Nokia and Microsoft are adopting it as part of their official application development platform.
  


• Can't get enough of these RIA frameworks comparisons? Here's another one, which is a short comparison/intro of three Rich Internet Application frameworks: Adobe AIR, Google Gears and Silverlight. See also my (bit older) post here, which also includes JavaFX.
  


• Summary of an article by Martin Fowler on how Agile can be used in building SOA implementations. The answer: yes you can quickly get value out of it. The biggest proof is the internet: loosely coupled and many unexpected changes.
  


• Quick-start JSF book free for download. Only 65 pages. Beginners level, step-by-step. With some mixed "infomercials" about the soon to be open source Eclipse IDE extension Exadel Studio Pro, but not in an annoying way.
  


• Key API design points from Joshua Bloch, Chief Java Architect at Google
  


• An explanation why a canonical message model (CMM) is a "good thing" in SOA and ESB.
  


• How to manage and lead geeks in a team. For technical and non-technical teamleaders.
  

Best of this Week Summary 15 September - 21 September 2008

• It seems the SOA world is finally starting to take the Web-Oriented Architecture seriously.
  


• Summary of a recent whitepaper from IBM Global Services describing five high level best practices for successful deployment of an SOA. 120 IT Architects, developers, IT Specialists and project managers evaluated nearly 100 case studies, with 750 lessons learned and 650 best practices.
  


• SpringSource announced a maintenance policy for SpringSource Enterprise. Definitely check Rod Johnson's clarification comment in this thread on The ServerSide. Important to verify when you're using Spring in your company.
  


• Elaborate introduction to persistence, ORM and JPA, and a comprison of two open source persistence frameworks: iBATIS and Hibernate. Notable points: iBATIS encourages the direct use of SQL queries; it enables the object model and the data model to be independent of eachother via its data mapper (compared to a metadata mapper framework like Hibernate). Note that fully ORM tools generate SQL, where iBATIS uses SQL directly. A nice quick overview of the Hibernate architecture is described; the diagram is shown below:
  
  
  Recommendations from the article:
  
  1. Use iBATIS when you need full control of the SQL
     
  2. Don't use iBATIS when you are in full control of both the application (with its domain model) and the data model.
     
  3. Don't use iBATIS when the database is non-relational
     
  4. Use Hibernate to leverage end-to-end OR mapping
     
  5. A potential reason to use it could be that it is more easy to use for object-oriented programmers who are less familiar with SQL
     
  6. Use JPA when you need a standards-based persistence solution
     
  
  
  My own recommendations:
  
  1. With Hibernate it might be harder to tune the queries because they are generated by Hibernate. You can't really "just handover" the queries to the DBA. The DBA will have to monitor the database for bad queries.
     
  2. Hibernate gets quite complex when you have to map more complex associations (like a unidirectional many-to-many association with custom columns added to the link-table). I've never used iBatis so can't tell how hard it is for that framework.
     
  3. When trying to only use JPA defined elements, you'll find that JPA's possibilities are quite limited (e.g. caching is not well defined in JPA), and that you quickly will start to use (ORM-tool) implementation specific features. A good way to implement this, is to specify the full package path when using implementation specific annotations. That way you can see where you deviate from the JPA standard.
     

Best of this Week Summary 8 September - 14 September 2008

• An interview with leads of PHP, JavaScript, Ruby, Perl, Python, and Tcl on the state of these dynamic scripting languages.
  


• Interesting technical development: IE8 and Google Chrome are putting tabs in new processes instead of threads. The main reason for creating threads used to be that it takes a relative long time to create a new process and inter-process communication is slow. But, these days the processor speeds are so fast (following Moore's Law etc), creating processes is a piece of cake/can be done really fast.
  


• How do individualism and teamwork go together in an Agile development project. Why type of roles should you have and what to expect from those roles.
  


• A short comparison of 8 java web frameworks: Struts 2, Spring MVC, Wicket, Tapestry, MyFaces, JSF, Grails and Rife.
  

Best of this Week Summary 18 February - 23 February 2008

• Nice overview showing how a Ruby on Rails Facebook application named "Friends for Sale" scaled to handle 200 requests/second and 300M page views per month. Includes the used hardware, software, # of visitors etc.
  


• This is a short article describing Comet, one of the better known technologies to push events from the server to the browser client. Also explains the name Comet (I for example thought it was a software product, not a technology).
  


• Reference to a thorough thesis (conclusions in the article) on performance of AJAX applications for 12 frameworks on mobile devices. Also 5 larger AJAX websites on mobile devices were compared.
  


• Nice (but not very elaborate) comparison of 9 features and benchmark of four JEE 5 servers: JBoss 4.x (OSS), Glassfish 2.1 (OSS), WebSphere 2.0 CE (OSS) and WebLogic 10. Check the reference to the jRealBench (zip) benchmarking tool.
  


• IBM has just opened their Jazz tool for beta. This post is a short description of installing and using it. Jazz "is a collaborative development environment product based on Eclipse, designed to support the application of RUP, which is itself an interative software development process framework built around iterative". But as you can see in the comments, it's not really restricted to RUP.
  

Best of this Week Summary 14 Oct - 21 Oct 2007

• Very interesting post about the Fotolog architecture. Note that they re-implemented a PHP part of the site in Java to improve performance! And they have to be scalable regarding these numbers for example: "300 Million photos and over 500,000 photos are uploaded each day. Over 30,000 new members are added each day and attracts more than 4.6 million daily users."
  


• This is a good comparison and overview of 4 open source version control systems: CVS, SVN, Bazaar and Mercurial. The last two take a distributed repository approach, in contrast to a central repository approach like CVS and SVN.
  


• Good high level overview of the history of software development. From the Waterfall Model to the current Agile (Iterative) Model. The main gain in all these years is that now it is possible to create quite complex systems with significant less persons because of the progress modern program languages and libraries have made. All of which you already knew of course, even if you didn't start in the 70's... ;-)
  


• James Gosling made the (quite logical) announcement earlier this week that in the future (mobile) devices will get so powerful there won't be the need for a separate Java Micro Edition anymore; there will be only one Java SE (Standard Edition). Also a few interesting points about the upcoming Java 6 update N (preload of the Consumer Java Runtime at computer boot), which should be available a few months into 2008, preparing the desktops for JavaFX.
  

Hands-on experience implementing OpenID

This is my third post about OpenID. To get you started, see my previous posts here and here.
In this post I'll be providing an overview of programming libraries that implement the consumer (a site that enables an OpenID login) and/or identity provider (service/site where a user has registered her OpenID), and also my experiences with them.
For many programming languages an implementation exists (both consumer and server). Libraries are available for: Java, C#, C++, Perl, Python, Ruby, Coldfusion and PHP. For an extensive list of these libraries, see this list.

My experiences with PHP libraries
As I mentioned in my first post, I've been working on a project where I had to add OpenID to an existing site. This site was built in PHP, so I had to look for a consumer library to OpenID-enable the site.
At first I looked at the high-quality opensource OpenID libraries provided by JanRain, Inc, which you can find here. These support also older PHP versions, from PHP 4.3.0 and upwards. The site I had to add OpenID to, still runs on an older PHP version, so this requirement was met. But after trying to integrate the library, I found out that it requires many PHP extensions the customer who the site belongs to, did not want to install all of them. For example PEAR::DB is needed if you use SQLite, PostgreSQL, or MySQL to store the OpenID data. (You might wonder: who does't use PEAR::DB? Well this customer doesnt' :-) Note that you might get away with a FileStore, as mentioned in this EasyOpenID implementation.

So to make the implementation more lightweight (I only needed a consumer supporting OpenID 1.1, preferably w/o any PEAR dependency), I started to look for alternatives. The most lightweight PHP library I could find was the Simple OpenID PHP Class. The only requirement it has is CURL. Basically it is only one PHP class file. It did contain some bugs originally, in the forum of the class you can find the most up-to-date code with a bunch of fixes.
Since the site I had to modify already had existing users, I had to come up with an implementation plan that handles migrating them too. This meant allowing existing users to be able to have an OpenID too. One problem is: how do you associate them with an OpenID? We basically did the same thing as is elaborately described in this nice article from Joseph Smarr, who implemented OpenID for their Plaxo platform. A recommened read if you're about to do the same job!
Basically, the implementation of adding OpenID to an existing site is a significant task. Your users will not see much change from the outside, but internally you most likely will have to modify your login flow, your forgot password flow and your change password flow. Still, providing your users to register with an OpenID is definitely a step forward for the user-friendliness of your site.

Other libraries
My main interest lies in Java, so I was seriously interested in the Java versions of these libraries. I've looked at the code of the OpenId4Java implementation, which originally was created by Sxip and donated to the Google code system.
It supports auto-detection for OpenID version 1.1 and 2.0. If for example the consumer finds out the OpenID version supported by the provider is not 2.0, it will create a client-nonce and append it. Thus a really elaborate library. Check here for a quick introduction btw to see what a nonce is.
But sadly I've not yet been able to integrate or implement one of the Java libraries.
A few note on the Java libraries listed at openid.net:

• The idprism.org link is dead.
• The NetMesh site gives quite a few warnings about the libraries being unsupported or in pre-release.
• As mentioned above, the Sxip library can now be found at Google Code.
• The "Informed Control Schemat Consumer, AX attribute metadata retriever" is not really a consumer/provider library, but a library for parsing and generating RDF.

Conclusion
I definitely recommend the mentioned PHP class if you only need to build a consumer with OpenID 1.1 support. If you need OpenID 2.0 support, I recommend one of the JanRain libraries. If you don't want to use PEAR::DB, you might be able to get away with this EasyOpenID implementation of a consumer. If you're using CakePHP, I'd recommend checking the OpenID module built for it (I've not tried this library). I've not been able to try out any of the Java classes yet, but I'd definitely recommend checking out the above mentioned quality implementation.

Eight top OpenID providers comparison

This is my second post in a series on OpenID. See my previous post here.
For a project I did, I had to add OpenID to an existing website. One requirement of the project was that external OpenID providers should be used (thus the site would not also "be" an OpenID provider). To make sure the newly added code to support OpenID registration would work with most OpenID providers, I tested quite a few of these providers. This gave me quite a good overview of what functionality OpenID providers (should) provide, and how they compare to eachother. The OpenID providers I used for testing and this comparison are a sub-list from here.

The comparison table below lists each OpenID provider and gives a comparison of the most important features these providers (should) support. To be part of this comparison, the provider has to provide all functionality at least in English.

OpenID provider details the OpenID providers.
Version shows which OpenID version is supported. Listed will be either 1.1, and/or 2.0 (still in draft), and/or XRDS and/or Yadis.
HTTPs indicates whether HTTPs is enforced during the authentication, even if you type in the OpenID without the protocol (i.e. no leading http:// or https://).
Login redirect indicates whether the OpenID provider will allow you to login from a consumer (regular website that provides an OpenID login) by redirecting the user to the OpenID provider's login page. Already a few providers don't allow you this anymore. They will send the user to a very basic page, telling the user to first login to the OpenID provider. This page usually does not even contain a link to the login page. That page mentions that not putting a link on the page is to prevent phishing. I don't see that. How does not showing a link prevent phishing? A user would only know there is no link on that page if she has ended up on that page before. And even if she has seen the page before, would she remember that if ever ending on a phishing page with a link to the supposed login? I doubt that.
Simple registration ext indicates whether the OpenID provider supports this extension which allows very basic profile information to be passed back to the consumer. Examples are an email address and the nickname.
Personas allows you to assign a multiple of those profiles to the same OpenID (URL).
Additional features lists any specific features worth mentioning.

OpenID provider	Version	HTTPs	Login redirect	Simple registration ext	Personas	Additional features
WordPress	1.1	No	No. Shows after login whether you want to continue signing in.	Yes	1	N/a
LiveJournal	1.1, Yadis, XRDS.	No	No. But shows username + password fields on the landing page.	No, e.g. nickname is not passed back.	0. Could not find where to enter e.g nickname.	N/a
AOL	1.1, Yadis.	Yes	Yes	No	0. Could not find where to enter e.g nickname.	The OpenID takes the form of openid.aol.com/yourname instead of yourname.aol.com or similar.
VeriSign PIP	1.1, 2.0, Yadis, XRDS.	N/a	No. Does not show whether you want to continue after login.	Yes	1. At authentication you can indicate which fields should be passed back. You can also create new custom fields!	Still in beta. I do remember seeing multiple personas but it seems they dropped it. Very basic landing page if you go to the OpenID URL.
MyOpenID	1.1, 2.0, Yadis, XRDS.	Yes	Yes	Yes	Yes, many.	Very elaborate OpenID provider. Provides the most functionality. From JanRain, Inc, which also provides many libraries for implementing OpenID.
GetOpenID	1.0, maybe 1.1.	Yes	Yes	No	0. Could not find where to enter e.g nickname.	The OpenID takes the form of getopenid.com/yourname instead of yourname.getopenid.com
Videntity.org	1.0, maybe 1.1.	No	Yes	No. At least, you can fill it in on a profile page, but I noticed multiple sites not being able to find any nickname in the OpenID reply.	1	Strange that they seem to support a profile, but I couldn't get it to return for example a nickname when logging in with an OpenID. In any case, on the page where you have to allow/deny, it does NOT show any of the fields I filled in on the profile page.
ClaimID	1.0, maybe 1.1, Yadis, XRDS.	Yes when you specify the protocol in your OpenID	Yes	Yes	1. If you haven't filled in your profile, you can enter it there on the spot.	The OpenID takes the form of claimid.com/yourname instead of yourname.claimid.com.

I was really surprised to find out that not all providers perform the authentication in HTTPs. Sounds like a basic security feature that be enabled by default as OpenID provider. Also all above OpenID providers seem to be run by a commercial company. Not many non-profit versions exist (like mijnopenid.nl). This one I did not include because it is in Dutch.

If you want a free anonymous OpenID, check this Anonymous OpenID server. Note that anybody can use that anonymous OpenID since it requires no authentication!
This service lets you use your Yahoo! account as an OpenID.

Conclusion
Based upon the above table and my experience, the most secure (i.e. HTTPs), solid (not in beta) and flexible (multiple profiles) OpenID provider is myOpenID.com. Of course you should try not to be dependent on one provider and therefore use delegation; see my previous posting for an explanation of delegation.

Best of this Week Summary 15 - 21 July 2007

Related to this posting which mentions a good article about Continous Integration (CI), I found this interesting article which compares four open source CI tools: CruiseControl, Continuum, Luntbuild and Hudson. In short it is telling you:

CruiseControl:
+ Open source
+ Actively checks your source control system (SCM) for changes
+ Good notification options (including RSS)
- Bit more complex to setup
- Wrapper Ant build script/Maven SCM plugin needed
- Inter-project dependencies not a strong point

Continuum:
+ Open source
+ Easy setup
+ Strong Maven integration
+ Good notification options (though no RSS notification)
- Less extensive list of suppored SCM
- Checks SCM changes on user defined scheduled times (so not actively)
- Inter-project dependencies not a strong point

Luntbuild:
+ Open source
+ Easy setup
+ Most feature-richh of the OSS versions
+ Supports inter-project dependencies
+ Supports many SCMs
+ Separation of build scripts and schedulers
- Not so many notification options
- Checks SCM changes on user defined scheduled times (so not actively)

Hudson:
+ Easy setup (war deployment)
+ Scheduling and ability to poll SCM for changes
+ Good built-in JUnit support
+ Unique fingerprint per build so you can easily find out what was in that build
+ Supports inter-project dependencies
- Not so many notification options (but RSS is available)
- Supports not so many SCMs
- Lack of flexibility (e.g Ant build.xml has to be in your project's root directory)

Conclusion
Looking at the above +s and -s, my conclusion is that for smaller projects where inter-project dependencies are not important, CruiseControl or Continuum can be used. For larger projects with inter-project dependencies, Luntbuild and Hudson are a good option, though you really have to evaluate whether the new kid on the block Hudson is currently mature enough to be used in large projects.