Must read and apply: "TOP 25 Most Dangerous Programming Errors"

Nothing really new here, but still a good reminder for architects and development teams. And nice to see this being pushed to CS curriculums.

 Via http://www.sans.org/top25errors/#s4

Tagged architecture Developer Development Programming Security Software Tutorial

Liked "A Low Impact Woodland Home"

Tagged architecture Design House Permaculture Straw Wood

And here is the 400+ years old door of our rental place in Provence, Sisteron

Tagged architecture Door History House Old Provence Sisteron Wood

Pretty cool 400+ years old carved beam in the Provencal place that we rented for the next 2 months


But really scare our Californian baby girl: no worries there is no earthquake here!

Tagged architecture History House Old Provence Sisteron Wood

REST Web services resources for Java developers

Representational State Transfer (REST) is an architectural style for creating, maintaining, retrieving, and deleting resources. REST's information-driven, resource-oriented approach to building Web services can both satisfy your software's users and make your life as a developer easier.

via javaworld.com

REST Introduction

- The father of REST, Roy Fielding, dissertation on "Architectural Styles and the Design of Network-based Software Architecture"

- Why REST?

- For more resources see REST Wiki, including the REST in plain English article.

Building REST Services

- RESTful Service

- Building Web services the REST way

- Build a RESTful Web service

REST related Design Issues

- Versioning REST services

- Common REST mistakes

- PUT or POST: the REST of the story, or see also the interesting interview with Elliotte Rusty Harold

- Asynchronous REST or Slow REST: 

- Instead of returning a custom object we could use the Content-Location header for the in-progress status URI of the requested operation. This URI could also use headers to provide information regarding the in-progress operation:

- Status-Code: "202 in progress" or "204 No Content" when completed or any error code

- ETag: for the operation progress status. Could be strong and still give a notion of progress

REST for Java Developers (via javaworld.com)

- Part 1 - it's about the information, stupid

- Part 2 - Restlet for the weary

- Part 3 - NetKernel

- Part 4 - The future is RESTful

REST Libraries

- Notes: 

- All of them are supporting JAX-RS, aka JSR-311, the Java API for RESTful Web Services

- And here is good presentation of JAX-RS

- Restlet project

This is my favorite library, and I like the fact that it is running on GAE/J and supporting GWT

- RESTEasy from JBoss.org

- Jersey part of Sun's GlassFish project

- CXF from Apache.org

- REST Libraries usage trend:

JAX-RS Implementations

Via GoogleVolume.com

Tools

- RESTY is a simple cURL-based command line tool

- rest-client is a Java-based GUI and command line tool

- HTTP4E is an Eclipse HTTP client

 

Update 1: Added a libraries and tools sections.

Update 2: Added a section on design issues related to building REST services

Tagged API architecture Design Developer Development HTTP Java Library Protocol REST Software Tool Web Services

Trying to apply a MapReduce concept to synchronization

Trying to figure out if the MapReduce concept could be adapted to a synchronization process (server side mostly). I.e. could we find independent, parallelizable work unit? My first thoughts tend to be a yes. Hereafter is my first high level draft, on which I will work on and refine.

  • Coarse level: each data section (or database) could be an independent work unit
  • Could be problematic for interdependent section like container (or group or folder or etc.) referencing new item in another data section. Possible solutions: only parallelize the independent sections or use an optimistic approach and reduce could finalize potential identifier mapping
  • Pretty coarse level, but easy to implement
  • Fine level: each data section item could be an independent work unit
    • Would provide an easy way to parallelize the core of the synchronization process (duplicate detection, merging, field level conflict, etc.)
    • An improvement would be to put in the work unit n items, and the n could be dynamically calculated based on resources (memory usage, number of threads, network latency, etc.) availability and consumption (opposite effects)
  • The reduce part is aggregating the synchronization process intermediate results to produce the result of the overall sync process
    • Would be not easy to find a solution working for any type of synchronization protocol like OMA DS, a.k.a. SyncML, or FeedSync 
  • Perform a double stage MapReduce with both coarse and fine levels
  • The MapReduce concept could be easily applied at a server instance level, which will result in parallel thread, but also at the cluster level as it is the real intend of MapReduce
    • At the server instance level the changes to integrate a MapReduce programming level should be easy by wrapping the core synchronization process
    • At the cluster level, the changes are more dramatic as impacting the intrinsic architecture and the deployment
    • We would have specialized node (process or server instance) like map, synchronization, reduce, etc.
  • The protocol and session handling would be around the MapReduce architecture
  • A synchronization process is always involving data and data storage either through a direct persistent storage access (database, etc.) or through a higher level service managing the data storage access
    • The specificities of the data storage (latency, atomicity, transaction, etc.) would also directly impact the granularity of the Map
    • In synchronization, the performances are almost always dependent of the data storage performances. I.e. direct impact on the design of integrating MapReduce
    And now let's the fun begin to work out all the details and most importantly validate the feasibility.

    Tagged architecture MapReduce synchronization

    Art of scalability - Scalability principles

    Good introduction or refresher for people having to deal with scalability issues or architecting some services that will need to be scalable. See the series at hfadeel.com. Couple this series with his Performance Anti-Patterns post and you'll get a good overview.

    Comment: those posts are just scratching the surface of scalability, and is missing for people starting to deal with scalability a list of good resources providing more specific details and information. I guess I could do something here...

    Tagged architecture Performance Scalability
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