howdy, Julius!

hi Mark

how can I help you today?

(well I will be seeing you hopefully - lucky up got up at 545am yesterday and captured the URL as I started getting 503w)

yeah, that was quite the fiasco

I have a concurrent write database issue

I have a long running task which downloads information from a service provider in batches and then populates a local database

this takes quite some time as there's a fair amount of information.

at the same time a user can download a file and some state gets written to the database

if I get two writes I get a database is locked error

correct

I can catch this, but unfortunately the state in the views is no longer good for the user

I was just wondering if you had any advice... (I hope that made some sense)

don't do concurrent writes

heheh

:)

either make your "long running task" an IntentService and have the "some state gets written to the database" be handled by it

is there any way I can queue up database transactions?

or use Java synchronization mechanisms

the IntentService gives you a queue

or use a LinkedBlockingQueue from java.util.concurrent, along with your own thread to monitor it

ah it is an IntentService so maybe I need to merge these operations (sounds like what you're saying)

it's one solution

that sounds very smart - actually goes back to something you mentioned to me once before

btw - when you say the IntentService gives a queue, is that because it's all in one thread?

plus, there's a queu

er, queue

every onStartCommand() pops the Intent onto the queue

the background thread kicks off

grabs first Intent off the queue, and calls onHandleIntent()

when done with that Intent, sees if anything else is on the queue

if yes, lather, rinse, repeat

if no, stopSelf() and shut down the thread

It's using the queue mechanism inside of a Looper

ah ok... wow thanks for that - I had no idea.

it's actually a fairly short class

hmmm so the downside for the user is that if the sync process is happening the download will have to wait

the download doesn't have to wait

updating the database has to wait

it's up to you whether those two operations are tightly coupled or not

oh I see so maybe I handle the database operations separately...?

That could work

it's only temporary

I meant do the download separately from the database operations

if that's possible for your app

oh yes

what I meant but expressed correctly.

no

not expressed

ok thank you very much

well I'd booked tickets and hotel so thank goodness I managed to save the state of my registration in a URL which I later put into a browser 3 hours later - so I hope to see you so you can put a face to the name

and I can thank you in person!

oh I have one other questions

question

bear in mind that there's a zillion people attending I|O

(yeah I'll be brief :))

it's actually a bit tough to run into somebody

well I'll do my best

being in NZ it's unlikely I'll get to meet people again.

so

I have had a few projects come up where people mention using tools like PhoneGap

this build for multiple platforms - iPhone, BB, android etc

yup

build => builds

have you any experience with this - know any pros / cons?

for my own part it could create some competition but I'd like to know whether I should be learning these tools

(as if Java and Android isn't enough)

PhoneGap is covered partially in _Android Beyond Java_, and that chapter is moving to _The Busy Coder's Guide to Android Development_ in the next release

I have not used it anywhere but Android, though

oh oops I didn't see that

I'll go take a look

thank you

of all the alternative application frameworks, it's my favorite

however, it assumes you're decent with HTML/CSS/JS

yeah not exactly my area

particularly AJAX-style, the whole-app-is-a-page sort of app

there was one I tried using something called lua but the apk was massive fro memory

thanks for your time.

that too is covered in _Android Beyond Java_, in the NDK chapters, that will eventually move to _Tuning Android Applications_

Lua is not designed for full Android apps

more of a scripting language, kinda like how it is used in WoW and such

hi again - just noticed that there's a <<TBD>> under the Using PhoneGap section and the following headings are empty. (just downloaded from your site).

Not a problem for me

I'm just getting a feeling for it so that was brilliant to read.

that book is a work in progress

or was, anyway]

ah right no worries

:)

that chapter will be completed for the next edition of _The Busy Coder's Guide to Android Development_

ok I'll leave you in peace - thank you very much for the help - that database issue was starting to creep into my sleep!

bfn

see ya!