Tech stuff: November 2009

2009/11/29

Accessing GSM SIM-Cards under Ubuntu

I borrowed a cheap GSM SIM-card reader and tried to use it under Ubuntu. The "Zolid" card reader is both a memory-card reader as well as a SIM card reader. The device presents itself to Ubuntu as follows (including the typo):

$lsusb
Bus 001 Device 005: ID 0bda:0169 Realtek Semiconductor Corp. Mass Stroage Device

The 'Mass Storage Driver' that mounts SD cards just works fine out-of-the-box. I concentrated my experiments on the SIM-card reader. I installed the 'MonoSIM' application to access the device.

http://www.integrazioneweb.com/monosim/
install the debian package. After some google-ing, I found a package at http://linux.softpedia.com/progDownload/monosim-Download-27949.html
under ubuntu, the package installer is automatically triggered and all associated packages (like libmono) are installed if needed
make sure the 'pcscd" smartcard daemon package is installed - check with Synaptic

In Applications/Office you can run the MonoSIM application and manage all phone numbers on it.

Some scripts that might be useful:

combine the 'monosim' file records to 1 line per record
$ cat *mono* | while read a; do read b; echo "$a;$b"; done | sort -u > gsm.csv
I used OpenOffice to filter out old lines and save the file back to csv
converting the csv back to the 'monosim' format:
$ while read a
do
echo $a | cut -d '"' -f 2
echo $a | cut -d '"' -f 4
done < gsm.csv > gsm.csv.monosim

The MonoSIM application works fine; the trick is to reconnect whenever a menu-item is greyed out.

see also: http://www.barrydegraaff.tk/index.php?page=files/Archive/Linux%20Sim%20Card%20reader/index.html

2009/11/24

Fixing Auto-mount Problems of a USB Device in Ubuntu

On one of my laptops with Ubuntu 9.10, USB memory sticks would only mount after several plug/unplug attempts. I investigated the problem and found a solution.

Diagnosis:

$ tail -f /var/log/messages (or call dmesg)
...
Nov 24 21:33:41 michael-laptop2 kernel: [ 2592.748078] usb 2-1: new full speed USB device using uhci_hcd and address 2
Nov 24 21:33:44 michael-laptop2 kernel: [ 2595.113326] usb 2-1: configuration #1 chosen from 1 choice
→ only after several attempts, the log would display "Initializing USB Mass Storage" and proceed with the auto-mount.
$ sudo lsusb
Bus 002 Device 002: ID 041e:200c Creative Technology, Ltd
→ in this case, the USB stick is an mp3 player
$ sudo lshal
...
udi = '/org/freedesktop/Hal/devices/usb_device_41e_200c_4002FA76125D8F8A_if0'
info.linux.driver = 'ndiswrapper'
(string) info.parent = '/org/freedesktop/Hal/devices/usb_device_41e_200c_4002FA76125D8F8A'
(string) info.product = 'USB Mass Storage Interface'
(string) info.subsystem = 'usb' (string) ...
→ the "41e_200c" USB device has been wrongly associated to the ndiswrapper module.

Conclusion: my old experiments with ndiswrapper and the rtl8187b wifi device still left traces on my Ubuntu system I upgraded to 9.10.

Removing ndiswrapper was a bit tricky:

$ sudo ndiswrapper -l
net8187b : driver installed
device (0BDA:8189) present (alternate driver: rtl8187)
$ sudo ndiswrapper -r rtl8187
in synaptic: remove all the ndiswrapper-* packages
$ sudo rmmod ndiswrapper
$ sudo gedit /etc/modules
→ remove ndiswrapper line
$ sudo rm /lib/modules/$(uname -r)/kernel/ubuntu/ndiswrapper/ndiswrapper.ko

Now, usb sticks mount from the first time.
see also: https://help.ubuntu.com/community/WifiDocs/Driver/Ndiswrapper
update 25/11/2009: apparently, the ndiswrapper is part of the ubuntu distribution. After applying the latest security-fix, the ndiswrapper module re-appeared.

update 6/6/2010: the ndiswrapper bug still exists in Ubuntu 10.4.

2009/11/19

Devoxx 2009: Performance for the Performance-shy

19/11/2009, Holly Cummins, IBM

costs of bad performance

electricity
employee productivity
lost business (e.g. slow pages)
hard cash (e.g. trading)

tuning technique

find the bottleneck in the application
- cpu → consistently high
- I/O → cpu not consistently high
- lock → cpu not consistently high
- space ??? cpu can be low or high ...
what is the JVM doing? → tools … must have:
- visual indicators
- explanation
- suggested solution (command line)
measure performance
- risk to make it worse
- get a baseline
- system must be as similar as possible to production
- how:
  - System.currentTimeMillis()
  - warm up your system
    - JIT
    - trigger caches

tools: IBM Perfomance Tools

for IBM jvm's
free
IBM Support Assistant: centralized repository for IBM tools

space-bound applications: heap

diagnose:
- lower throughput
- crash (out-of-memory exception)
- trigger gc's → higher cpu
tools:
- verbosegc: very low overhead → use on production
- live memory monitoring → IBM Monitoring & Diagnostic tools for Java
  - GC and Memory Visualizer
    - for Websphere → also works on Solaris & HP-UX (i.e. sun jvm syntax)
    - heap details, including heap histogram
    - get dominator tree
    - search inefficiently used data structures & redundant data
    - recommendations
      - increase heap size
      - gc takes between 10% - 20% cpu → tune gc policy
  - Health Center
    - agent in JVM
    - client (IBM Support Assistant)
    - visualize gc
    - recommendations
    - check gc performance
- Memory Analyzer (not from IBM → eclipse.org): diagnose footprint issues:
  - heapdumps
    - automatically on out-of-memory
    - trigger programmatically
    - tool support is essentialµ
- OS-tools
  - track native memory: perfmon, vmstart, ps (os-specific)
  - use gcmv to visualize os-specific dump
  - some native structures have java-wrappers in the heap (e.g. Threads and NIO buffers)

cpu-bound applications

target your optimizations → measure
diagnose:
- method trace:
  - System.out.println()
  - log4j
  - ibm-jvm param -Xtrace:print=mt,methods=(HW*)
- method profiler:
  - health center: low overhead sampler

I/O bound applications

gc and memory analyser → long gc times might indicate paging
method trace for network and disk I/O
os-specific tools

synchronization issues (concurrency)

sample thread dumps
health center:
- lock analysis
- identify contended locks

Devoxx 2009: The not so Dark Art of Performance Tuning

19/11/2009, Kirk Pepperdine & Dan Hardiker

loadtest <> stresstest:
- loadtest: test user experience
- stresstest: find when the application breaks
performance anti-patterns & solutions:
- lack of stress testing → introduce a stress test harness
  - repeatable test
  - control load
- shot in the dark: fix ugly code
  - ugly code runs just fine
  - measure, don't guess!
Apache JMeter → root node: “Test Plan”
understand the environment, identify dominating consumer → look at the full system
- actors: usage patterns
- application
  - locks
  - external systems
- jvm/os
  - memory
  - hardware management
  - tools e.g.:
    - vmstat on hpux
    - jps
    - jstack
    - visual vm (thread and heap dumps)
- hardware
  - cpu
  - memory
  - disk I/O
  - network
response time budgets:
- detail the time of the different components → add customizable time measures
  - database
  - application server
  - client
common problems, demo's:
- poor response times, low cpu
  - thread pools
  - locks
  - → VisualVM, thread dump + plugin thread dump analyzer, identify lock

Devoxx 2009: Using XML with Java: Sploit for Choice?

19/11/2009, Michael Kay, Saxonica

Xml interfaces in java, from low level to high level

SAX/Stax
- high performance: +/- 40 MB/sec
- low-level
- SAX/Stax: comparable performance
- use pipelines:
  - SAX: push
    - best for multiple output
  - Stax: pull:
    - best for multiple input
DOM: tree based
- don't use plain DOM, prefer JDOM, DOM4J or XOM – I once experienced problems with the XOM-handling of unicode characters
- uses a lot of memory: +/- 5 times the document size
- complex, tedious usage
databinding: compile to / (un)marshall from java objects
- like JAXB
- fits for simple xml
- not for complex xml or document xmls → create too much java classes
- give 2 views on the same: xml <> java objects
language support:
- doesn't exist in Java...
- scala: XQuery-like capabilities
XSLT/XQuery
- should be your default choice
- good performance: +/- 10MB/sec
- XSLT:
  - more for documents
  - transformations
  - richer functionality
- XQuery:
  - more for data
  - xml-database
  - easier to optimize

Architectures

prefer xml pipelines: (xproc pipelines)xml database → xquery → xslt → rest → xforms
don't mix data: objects & xml

2009/11/18

Devoxx 2009: Project Coin

18/11/2009, Joe D. Darcy, Sun

slides: http://blogs.sun.com/darcy/entry/project_coin_devoxx_2009

Project Coin

small language changes in JDK7
keep broad consideration of java landscape → remain consistent with the Java Language
bigger language changes, not in scope of Project Coin
- JSR308: annotations to improve static checkers (e.g. @NotNull)
- JSR294: modularity

principles of Project Coin:

reading more important than writing
- 'beautiful' code
- don't hide what's happening
simplicity matters
no slash-and-burn: remember broad user-base
balance stability versus progress
prefer library / IDE changes over language changes (String.join)
no new keywords
no type system changes
small in specification, implementation and testing

methodology:

open: blog entries / white board on Devoxx2008
call for proposals
prototypes recommended
- lot of work
- very beneficial → learn / find issues
existing requests for enhancement: 120 changes → too much

final list of Project Coin enhancements

numbers:
- binary notation: 0b00100100001
- group numbers with '_': long big = 1_123_456_789;
switch on a String – really cool!
- specification: only one word added
- proposal contains a suggested implementation:
  - uses String.hashCode() for an initial switch
- big patch in javac
- lots of tests to validate change
  - reject pre -source 7 classes
  - null behavior
  - hash collisions
  - fall-throughs
  - → comparable to enum switch control flow
diamond <> operator : type interference → e.g. Map <String,String> map = new HashMap<>();
- a lot of prototyping work
- quantitative analysis
- some concerns on language evolution were considered
JSR292: invokedynamic for dynamic languages
auto-close of Closable types within a special try block (ARM)
- try(File f = new File) {} → f is automatically closed when leaving the block
simplified varargs method invocation, working along with generics
language support for Lists and Maps:
- List<String> list = [“1”, “2”];
- list[0]
- map{“hello”}

not retained in Project coin:

Elvis operator:
- use ?: as a shorthand for testing on null
- conclusion from building a prototype→ doesn't fit well in java
multiple exception handling
- disjunctive means of | operator
properties:
- changes the type system
- a lot of work (e.g. reflection api, corner cases …) – the 'enum' specification is demonstrated as a comparable change that involved a lot of rework
- pseudo-properties workaround: via annotation-processing → Project Lombok
reified generics
- source language compatibility issues – java generic erasure was chosen for backward compatibility
- C# created a separate generic library
- difficult for other languages to target the a platform with reified generics
extensible enums
- most enums are constant
- low utility

Devoxx 2009: Solr Power with Lucene

18/11/2009, Erik Hatcher

Lucene core

full-text search library
concepts
- inverted index:
  - term + proximity
- documents
- fields
  - field-ids: e.g. category, title, name...
  - types: number, date, text...
  - unique keys: unique id per document
- terms (aka tokens):
  - processed through filters
    - synonyms
    - ignore words
    - stemming
- scoring relevancy
  - term frequency
  - inverse document frequency
  - field length normalization → control how field length / # occurrences affects scoring
  - boost factors: favor or boost some fields (e.g. titles)
core
- standalone jar
- core index

Apache Solr properties:

search server
based on Apache Lucene
- → Lucene exposed over http
- spell checking
- highlighting
extensible
scalable
- caching
- replication
- master/slave distributed search → sharding
multiple inputs
version 1.4

Using Solr

setup:
- solrconfig.xml:
  - cache settings
  - Lucene indexing parameters
API:
- RequestHandlers:
  - mini-servlets,
  - flexible responses:
    - http GET/POST
    - JSON
    - SolrJ
    - ruby, php, …
    - content streams (must be shielded)
- indexing / deleting a document
  - through api: xml document with commands
  - POST or GET with request parameters
- other actions:
  - commit / rollback: batching document indexing
  - optimize
- search request: simple GET, with optional parameters
  - debug
  - lucene explanation
  - pagination: start / raws
  - score: lucene score
DataImportHandler
- import from RDBMS, xml and e-mail
- incremental indexing
- extensible
- debug console
Solr Cell: uses Lucene Tika:
- index Word, pdf, html ...
- ExtractingRequestHandler
Query parser framework with plugable parsers:
- Lucene syntax:
  - powerful
  - but user-unfriendly syntax
  - exceptions visible to end-users
- Dismax query parser
  - simplified syntax

Advanced Solr: Search Components

standard: query, facet, mlt, highlight, stats, debug
others: elevation, clustering, term, term vector
faceting
- counts subset within results
- group 'facets' of a document (like a category field)
spell checking
pluggable distance algorithms: Levenstein or JaroWinkler
highlighting: custom prefix and suffix → response is highlighted
query elevation → elevate.xml: boost or exclude a document
clustering: grouping of documents into labeled sets
enumerate terms for a field
term vectors: term frequency, document frequency, position, offset
statistics: stats.jsp (in RAM); returns xml
scaling:
- replication:
  - master is polled
  - replicant pulls Lucene index / config files
  - replicate + load balance
- distributed search: single index is too large → sharding

Staring with Solr

agile, iterative process works best:
- basic schema
- bring in data
- check requirement gaps
- adjust solr

Devoxx 2009: Architecting Robust Applications for Amazon EC2

18/11/2009, Chris Richardson, SpringSource (VMware) www.cloudtools.org

Amazon EC2 cloud computing solution:

choose your virtual machine, with machine images of standard OS's
cloud services
- SQS: Simple Queue Services
- SimpleDB: alternative to relational DB
- S3: storage
- EC2 firewall: security groups
- Elastic Block Storage:
  - replicated, mounted as device
  - snapshots → backup
- Elastic Relational DB Service:
  - MySQL 5.2
  - maintenance window: 4hour/week
  - backup window
standard software: simply install (with yum or apt) your packages
console
local storage:

plenty (160GB → 1690 GB)
ephemeral
slow down on first access
→ Elastic Block Service

easy upgrades:
- clone your production environment
- upgrade the clone
- test the clone
- if OK: put the clone in production
- remove the old clone
regions:
- US
- EU
- Asia
- sub-zones:
  - “availability zones” that are isolated from each other.
  - better availability
  - more expensive

issues:

security:
- not PCI-compliant
- discomfort of putting your core data on the cloud
- where is your data really?
- but:
  - Amazon experience
  - unlimited logging
  - standard best practices for security
  - isolated instances
  - put servers in different security groups → Amazon EC2 firewall
  - encrypt your data and backups
cost:
- expensive for large servers
- bandwidth
- but: no extra cost of cooling, power etc.
machines:
- no very small, very big machines
- maintenance windows
- load-balancing:
  - ipbased: no support for sessions
  - dns (cname)
is it reliable?
- is internal IT better?
- Amazon expertise
- easy to launch a new instance within a few minutes

future:

Platform as a Service:
- complete stack
- simpler scaling, without being involved into the technical details
- Google Application Engine
- Cloud Foundry:
  - Spring & Grails

Devoxx 2009: JDK 7 Update

18/11/2009, Mark Reinhold

higlight: Closures in java are BACK!

Aims of JDK7

modular platform
- JDK7 status:
  - 13MB download with pack200 compression
  - difficult to support smaller (embedded) hardware
- → Jigsaw project
  - low-level modules, at the rt.jar level
  - language support: module-info.java file
    - explicit module / version requirements
    - create simpler OS-specific package, with correct dependencies (e.g. deb-packages)
  - OSGi interoperability
multi-lingual support
- better JRuby, Jython support on the JVM
- InvokeDynamic
- “Da Vinci Machine project”
productivity enhancement
- “Project Coin”
- language changes that improve programming experience. E.g.:
  - type inference with the <> (aka. 'diamond') operator: Map <String,String> m = new <> HashMap();
  - split numbers with '_' for better readability: int a=123_456_789;
  - support binary notation: int b=0b00100100001;
  - Lists: direct construction and access to set/get with []: a[4] = b[5];
  - Map: direct construction and access to set/get with {}: a{“b”}=”xyz”;
  - auto-close Closeable interfaces: try(File f = new File()) where f is always closed correctly.
performance
- multi-cores are there! → java support needed.
- → fork/join framework
- Dual-Pivot Quicksort
- Closures: “It's time to add them” – I thought this was dropped from Java7 plans...
  - needed:
    - function literals
    - function types
    - extension methods
  - “doesn't fit in java”:
    - non-local control transfer
    - capture non-final vars
    - library-defined control structures

When?

Planning shifted
Milestone 10: 2010/09/09: release candidate

Devoxx 2009: Keynotes 18/11/2009: Parleys.com, Oracle, Sun (JEE6) and Adobe

Stephan Janssen: Devoxx organizer,Parleys.com founder

presented his new Parleys v3
- support for 'spaces' and channels in spaces → propose parleys.com as a platform
- monetize:
  - subscription for impatient viewers (i.e. for immediate access to the talks); talks with free access are provided within a year
  - give private spaces to companies for education purposes
- still presented in the over-Flashy way
- I hope they'll get the podcast feed – finally – fixed.

Oracle slot

mostly boring management talk, with lots of empty words
WebLogic DM:
- heavily based on OSGI
  - 'Profiles' group technical bundles
  - 'Bundles' are the application-specific modules
- possibility to run on a “bare-metal” hypervisor VMWare: http://en.wikipedia.org/wiki/Hypervisor– new concept to me

Sun:

JEE6
- final release scheduled for 10/12/2009
- → enterprise development made simpler
- basic contents (a.o.)
  - new stuff:
    - JAX-RS: annotation-based RESTfull API
    - Bean validation, used in the full stack (JSF and JPA)
    - Dependency Injection (DI) 1.0
  - updates:
    - EJB 3.1
    - Servlet 3.0
    - JSF 2.0
    - …
- support for technical profiles: set of basic, but quite complete JEE components.
  - e.g. WebProfile: Servlet 3.0, JSF, EJB 3.1 lite, DI
- pluggable, modular web applications
  - web.xml is now optional
  - web-fragment.xml
  - annotations:
    - @WebServlet
    - @WebFilter
  - resource jars → finally a standard way to package static resources
  - programmable registration API
- Dependency Injection 1.0:
  - @Resource
  - @Inject → Guice-like standard solution
  - Inject metamodel
- EJB3.1
  - @Singleton
  - @Startup
  - @Asynchronous
  - EJBContainer API, useable in Java SE (for testing)
  - EJB's, directly useable in webapps
- JSF 2.0
  - standard facelets
  - autodiscovery of component libraries
  - Ajax & partial view loading
  - JavaScript API
  - composite components
Glassfish demo
- Eclipse & NetBeans support
- not sure how Oracle will handle the GlassFish versus WebLogic proposal
- great programmers' experience:
  - fast startup
  - incremental deploys applied to a running application without restarting → JRebel-like feature.

Adobe stuff

skipped this one – too much flash for me :-)

2009/11/17

Devoxx 2009: A Year of Monitoring with Java-Monitor

17/11/2009, Tools in Action, Kees Jan Koster

Slides are available at: http://java-monitor.com/forum/showthread.php?t=646

Case-by-case approach from experiences reported on java-monitor.com, from an Operations' perspective.

Memory Leak:

diagnose:

Scavenger gc gives up and stop the world gc (= mark and sweep gc) takes over
monitor # scavenger gc's versus mark and sweep gc's

solution:

profile your app and fix your app
workaround: increase heap

Misbehaving GC

problem: System.gc() in code freezes the JVM!
diagnose:

many stop the world gc's (= mark and sweep gc)
low heap usage (e.g. 20%)

solution:

workaround: -XX-DisableExplicitGC
use findbugs and fix code

Native threads in 32 bit environments

problem:

OutOfMemoryException: Couldn't allocate native Thread
32bit Systems share 4GB with OS Kernel, JVM (heap + perm space) and thread stack space.

solution:

workaround: -Xss limitThreadStack
migrate to 64 bit!

In verboseGC: "promotion failed"

problem:

verboseGC logs "promotion failed" --> stop-the-world GC (mark and sweep) is triggered
CMS is non-compacting: the heap can end up to be fragmented. Fragmentation can prevent promotion of young heap (eden spaces) to old heap.

solution:

bigger heap
no real solution

File Descriptors

problem:

"too many open files"
files not properly closed on exceptions --> file description leakage
GlassFish opens file-descriptors for each static file served (efficient usage of FileChannels)

solution:

check ulimit / limits of your OS
fix your application (findbugs)

others

hyperthreading doesn't make any significant difference
use the magic "-server" switch

Devoxx 2009: Full Text Search for Hibernate

17/11/2009, University sessions, Emmanuel Bernard

Search solutions:

categorize upfront
show detailed search screen
use single search box (preferred)

Plain SQL search limits:

performance: like '%...%' causes a full table scan
no support for approximation nor synonyms
no proximity concept
lacking relevance scoring
no simple multi-column search

Full-text search solutions:

word based
captures / indexes frequency and position
solutions:
- RDMS: (like Oracle Text):
  - less flexible
  - not portable (vendor-specific API and behavior)
- standalone: Lucene
  - text-only
  - no synchronization with model objects

Hibernate Search, general features:

LGPL
uses Hibernate core
uses Lucene under the hood
solves object vs text mismatch
convert object to text document (+reverse) → Hibernate application uses objects, not text
documents
convention over configuration
heavily built on annotations
Optimize Lucene access:
- update Lucene docs on commit
- object graphs are consolidated to single Lucene docs to provide relevant searches
- avoid flooding Lucene indexer:
  - batch Lucene updates on commit
  - optionally trigger the Lucene indexer asynchronously
- support clustering (JMS)

Hibernate Search Annotations:

@Indexed
@Field: tunable how to convert to text with, among others, @FieldBridge. E.g. convert number to 0-padded number.
@IndexedEmbedded
@Boost: promote a particular field in the relevance score (can be at indexing time or at query time)
@Analyzer: e.g. anagram-support

Lucene Index as used by Hibernate Search:

event based
batches updates per transaction (=at commit time)
sync or async mode (optimize Lucenes' locking mechanism)

Query:

HQL
Full Text (Lucene syntax) e.g. with the ~ opperator
JPA2 criteria
native SQL
→ always returns Objects, not Lucene documents.

Advanced stuff:

tokenizer: split text in words, remove common words
complex searches: combination of indexing and querying
fuzzy search:
- “Levenstein distance”: quantifies similarity
- “n-gram”: word is split in groups of 3 letters → matching groups determines score. (demo looked a bit hackery)
phonetic search (soundex-like): disappointing in practice
synonyms: use your application-specific list
stemming: → 'reduction'
- Porter Algorithm
- Snowball stemmer
filters: provide efficient an pluggable support for
- security, categories, temporal data, caching...
“explain” query result

clustering / Scaling Lucene
- one Lucene writer at a given time
- use a JMS queue for indexing (→ 'Master')→ small delay, but very scalable.
- Distributed in-memory index (Infinispan 4.0) – technical preview
- index optimizations:
  - sharding
  - defragmenting or re-indexing

Devoxx 2009 – Google Application Engine - A Real Live Voyage to The Cloud

17/11/2009, University Sessions, Sam Brodkin and Scott Stevenson

Google Application Engine for Java (GAE/J) is a cloud computing solution that provides

a JVM
OS support
access to the Servlet API
a management console
access to Google utilities:
- Logon / Sign up → com.google...User
- image service: resize images
- mails
building blocks:
- DataStore
- MemCache

Cost model is based on actual usage, with a free quota for easy starting:

bandwidth usage (in/out)
cpu usage
datastore size
emails sent

Management console:

access to logs
shows bandwidth / cpu usage → cost
users with admin role
statistics
manage multiple versions: one default, and many test versions (beware of data-incompatibilities)

Limits of GAE/J:

requests timeout: 30sec
no background processes allowed
no server push
no threads
read-only file-system
no transaction
only access to white-listed classes (e.g. ImageIO class of java is not accessible → use Google Image service)
a maximum of 3000 static resources per application
Migrating your application off the GAE/J cloud: difficult, but not impossible → google for “GEA Bar”

DataStore for data persisency

not a relational database
BigTable → like a big HashMap
no transaction
JDO or JPA access

Development Environment:

eclipse plugin
Jetty based emulator → fair emulation, but not 100% relevant
MemCache
disk-based datastore
compile-time checks
no maven support yet
DIY ant scripts are possible and recommended.

Demo: “swagswap.org”

3 tiers:
- DAO
- service layer
- 4 frontends that use the same
  service layer:
  - jsf 2.0 (+IPhone version)
  - gwt 1.7
  - SmartGwt
  - Spring MVC
wired through Spring 3.0
get detailed cost of a request by setting a special HTTP header

Quirks:

BLOB type
Text type for long Strings
white-listed classes
- → find workarounds for blocked classes (e.g. Image services)
- → some thirdparty libraries don't work
JSF2.0:
- disable threading in web.xml
- no JNDI: hack WebConfiguration class
- server side state doesn't work → use client side state
- RichFaces, IceFaces and Commons FileUpload use non-whitelisted classes → incompatible with GAE
GWT:
- BLOB and Text are non-serializable
- GWT <> Spring integration requires a special service class
SmartGWT:
- requires 1000 static resources → closer to the max of 3000 of GAE → workaround with zip-file and cache, but increases cpu-cost

2009/11/11

Sound in Ubuntu 9.10 - Intel 82801G

The sound on my Medion MD96290 didn't work after upgrading to Ubuntu 9.10 (Karmik Koala). I experience this glitch on every Ubuntu upgrade - see my previous post.

My sound chip:

$ sudo lspci -v
00:1b.0 Audio device: Intel Corporation 82801G (ICH7 Family) High Definition Audio Controller (rev 02)
Subsystem: Wistron Corp. Device 4071
Flags: bus master, fast devsel, latency 0, IRQ 21
Memory at d8440000 (64-bit, non-prefetchable) [size=16K]
Capabilities: [50] Power Management version 2
Capabilities: [60] Message Signalled Interrupts: Mask- 64bit+ Queue=0/0 Enable-
Capabilities: [70] Express Root Complex Integrated Endpoint, MSI 00
Capabilities: [100] Virtual Channel
Capabilities: [130] Root Complex Link
Kernel driver in use: HDA Intel
Kernel modules: snd-hda-intel
...

Fixing is easy:

gksudo gedit /etc/modprobe.d/alsa-base
add one line to the end of the file:
options snd-hda-intel model=6stack-dig
save and reboot
rightclick on the volume icon and select Sound Preferences
in the hardware tab, select a profile with "Surround" in it.

update 6/6/2010: this tip also works for ubuntu 10.4.

2009/11/08

Tweaking the Full-screen Mode of Firefox

I like to use Firefox in full-screen mode (hotkey: F11) on my netbook. Unfortunately, Firefox hides the tabs and navigation bar and only shows the bar when your mouse pointer is on the top of the screen.

Luckily, it's easy to modify this default setting:

enter 'about:config' in the URL-field
confirm that you really will be careful
set the 'browser.fullscreen.autohide' setting to false (double-click on the line)

This gives me a Chrome-like browser experience with Firefox on Ubuntu, while maximally using the small screen size.