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- A post on experiences with Git coming from Subversion. Too bad the reasons why the author is having more and more problems with Subversion were not given. Though you can deduct (some(?) of) them from the text.
- Presentation by John Resig (from JQuery fame) on testing javascript. Shortly describes QUnit, JSUnit, YUITest for unittesting, Screw.Unit, JSSpec for behavior testing (unittesting broken up by task), Selenium for functional testing and Crosscheck, Env.js, Blueridge for server-side Javascript testing. Also describes browser launching, which I would translate into "build/test management", distributed testing (Selenium, TestSwarm) and browser support (cost vs benefit).
- "A Decade of SOA: Where are we, Where are we Going?" The viewpoints from a virtual panel of Enterprise Architects who have lived and implemented SOA for most of this decade.
- Why iStockphoto embraced Google's Gears.
- And as grand final this week: the hardware and (rails) software architecture of Ravelry, a knit and crochet community.
- 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.
- Last week was Oracle Open World 2009. Beside for Oracle DBMS and SOA specialists, these days the event is definitely also very relevant to Java professionals because of Oracle's (almost official) acquisition of Sun this year. Here's a set of relevant information from OOW:
- The keynote on sunday which also describes the plans Oracle has with Java, MySQL and Sun hardware
- James Gosling explaining to the developer audience what Sun was doing, what the scale is of Java activity around the world and across technology platforms.
- The Dutch software company Amis also did quite a few presentations at OOW. Some of those presentations were already online before they were actually presented! All were interesting:
- Good overview of what will be in the Patch Set 1 for the Oracle Fusion Middleware 11g stack, including JSF and ADF (mobile!). It's more than a patch!
- Edition Based Redefinition (EBR): "Every database object (well, almost every database object - not tables!) can have different implementations/incarnations/versions in various editions. The object versions are all in the same schema - they only differ in the Edition they are created in."
So no more direct table access! No big bang needed anymore. Challenges: what if a mandatory column is removed or added from the current EBR view (answer: special triggers). Including 2 suggestions for best practices.
- XML processing/design tips.
- This "session introduces SOA and the new Oracle SOA Suite 11g to the realm of database professionals from which it sometimes seems so far removed. What are the key SOA concepts and objectives? What is at the heart of Oracle SOA Suite 11g: composite applications, BPEL PM, and the mediator. The session shows how SOA services can be leveraged from the database, from triggers, PL/SQL units, or even SQL and how the database can publish events to the event delivery network. It covers how the SOA infrastructure can access the database, primarily using Oracle Database and Oracle Advanced Queueing adapter and how database developers can help in doing so efficiently. It ends with hints for applying SOA concepts to "normal" database development."
Bit oriented at the database professional, but still interesting for those who want to stay up to date with Oracle's DMBS possibilities. And a bit scary too: it is possible in 11g to make webservice calls and publish them from the database(!). For example from PL/SLQ and put a webservice in front of PL/SQL... I haven't come up with a practical situation where you'd want to do this from an architectural point of view: large risk to getting tightly coupled systems and dependencies. If you have heavily invested (i.e built) in PL/SQL, it might be a valid option though.
There is currently a renewed focus on the role of code generation in developing enterprise Java applications. Springsource recently released Roo, Skyway Software released Skyway Builder Community Edition version 6.3 and Blu Age released M2Spring. What should the software architects and developers look for in a Code Generation framework?
Seven Wicket Do's and Don'ts.
- A quite in-depth article on creating highly-scalable components in Java. Described are the ideas used to create the concurrent Java components in the Amino Library Project (a set of concurrent building blocks).
- Another SOA Design Pattern sample chapter from Thomas Erl' book "SOA Design Patterns": "Service Governance Patterns, comprising a number of 8 patters. Compatible Change and Version Identification deal with service versioning. Termination Notification addresses the final phase of a service, it’s retirement. Service Refactoring explains how to deal with changing service contracts. Service Decomposition, Proxy Capability, and Decomposed Capability include techniques needed to express coarse-grained services through multiple fine-grained ones. Distributed Capability helps increasing service scalability through processing deferral."
- To ESB or not to ESB? Including a nine points checklist. Note that the article is from the creator of Mule (a lightweight ESB). Check also the comments here.
- Interesting hack to reduce startup latency for mobile devices with HTML5: put the Javascript code in comments (thus /* */), such that is immediately downloaded but not evaluated. Then to load it when needed, parse the text, strip out the comment-tags & do an eval().
- "Tony Hoare introduced Null references in ALGOL W back in 1965 “simply because it was so easy to implement”, says Mr. Hoare. He talks about that decision considering it “my billion-dollar mistake”. Tony Hoare, is a British computer scientist, probably best known for the development in 1960, at age 26, of Quicksort. He also developed Hoare logic, the formal language Communicating Sequential Processes (CSP), and inspired the Occam programming language."
- "Peter Thomas has updated his web framework performance benchmark with Grails and Tapestry. Apache Wicket still leads the best of breed frameworks in terms of request times and memory usage." Other observations:
- Grails was far more productive than Tapestry 5. This was mainly due to the documentation quality of Grails compared to the scattered and not very well organized Tapestry documentation.
- Ease of writing custom tag-libraries is IMO one of the best things about Grails.
- Grails still has some way to go in terms of performance. I am told that significant performance optimizations for GSP will make it into 1.2
- Session usage of the Seam + JSF combination is significantly higher compared to all the rest, around 760 KB per session."
- "At the JVM Languages Summit, Josh Bloch expressed his concern about what he called the "semantic gap" between the source code we write and its performance at runtime: As performance improves, our ability to predict the performance consequences of our source code degrades." Feedback from people on this subject can also be found here.
- "Mckoi Distributed Database (MckoiDDB) is a database system used by software developers to create applications that store data over a cluster of machines in a network. It is designed to be used in online environments where there are very large sets of both small and big data items that need to be stored, accessed and indexed efficiently in a network cluster. The focus of the MckoiDDB architecture is to support low latency query performance, provide strong data consistency through snapshot transaction isolation, and provide tools to manage logical data models that may change dramatically in physical network environments that may experience similar dramatic change.
MckoiDDB is written in 100% Java and runs on any operating system that supports Java 1.6. MckoiDDB is released under the GPLv3 open source license."
- 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”."
- 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.
- Wondering whether you should add this new piece of functionality quick & dirty or take a bit longer, but cleaner? Taking the first one sets you up for a Technical Debt, as some more explained by Martin Fowler.
- "Test logic can be buried in this unrelated code, which has nothing to do with test logic itself, making test code hard to read and maintain. In this article, the layered architecture of test automation is presented to solve this problem. In this layered architecture, the test automation code is divided into three layers: (1) test cases, focusing on the test logic of the application, (2) the domain layer, modeling the system under test in domain terms, encapsulating http requests, browser control, result parsing logic and providing an interface for the test cases layer, (3) the system under test, which layer 2 will operate directly on."
- A good explanation of the Canonical Message Model in the context of an ESB, and why you'd need one within an SOA. Great description of different approaches for implementing a CMM in an ESB and their pros and cons.
A short introduction to CMM modelling (data model and message model) is described here.
- From The Open Group two free PDF books: "The Open Group SOA Integration Maturity Model (OSIMM) provides consultants and IT practitioners with a means to assess an organization’s Service Oriented Architecture (SOA) maturity level."
"This document describes a framework that provides context and definitions to enable organizations to understand and deploy SOA Governance."
- The JavaServer Faces 2.0 specification (included in JEE6) got finalised last May. Here's a reference to it and a set of references related to this specification.
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