howdy, Prasanna!

Hi Mark

Here is my question

Just want to run this by you ...

The scenario is that we want to create a background service that downloads information and makes it available to several widgits. These widgits should know when there is new information that is downloaded from the service. The widgits should also get access to this information when ever it wants to based on how the user interacts with the widgit. What is a good architecture for this? That is, do we need a remote service? Is it a good idea to get the background service to store the information in a mysql database and make this information available through a content provider? The widgit will need to change this data also. Should we let the widgits know that there is new information though a broadcast? Is there a good example of this?

By "widgits" do you mean "app widgets"?

Yes.

(btw, howdy, NetApex!)

Hello

"That is, do we need a remote service?" -- absolutely not

"Is it a good idea...content provider?" -- use AlarmManager and an IntentService to gather the data. How you make it available to the rest of your app is up to you.

Wont the service and Widget run in different processors

"Should we let the widgits know that there is new information through a broadcast?" -- no, because that is impossible. Just update the app widgets directly when the data changes.

"Wont the service and Widget run in different processors" -- no

while the app widget is displayed in a different process, that does not impact your code

no specific questions from me today

NetApex: do you have a question?

But if the widget want's to get access to an api that is exposed by the service then don't we need to implement a remote service?

sorry I can wait for NetApex to ask a question

Just one, and it is more of an, I need your opinion type of thing. (Go ahead and ask P)

Prasanna: widgets do not have "wants", because they do not have code, per se

widgets are RemoteViews

they are data structures

anything in your app can update the app widget RemoteViews whenever you want

so, app widgets do not "get access to an api that is exposed by the service" -- the service updates the app widget's RemoteViews

or something else (e.g., AppWidgetProvider) calls some API from the service and updates the RemoteViews

so if the AppWidgetProvider wants to get access to the service, don't we need to create a remote

service

no

the AppWidgetProvider is just a BroadcastReceiver running in your regular process

I am a little confused about the different processes that are involved ...

everything is in your process except for the home screen

ok. different apps of course run on different processes, right?

yes

ok. got it.

the home screen runs in its process

it receives RemoteViews from your app

and displays them in the app widget block of cells

ok. I have more q's but can wait till it's my turn next ...

I am working on an app that pulls data off of Google App Engine. I am wondering if I should have the data save into a database in the app, or just rely on there being a network connection. Say it was the score of a game and it is updated once or twice a week. If one were to view the data yesterday, and then reopen the app today without a network connection would the data be stored in memory, or would it rely on a specific database being created to keep the data there?

that's impossible to say

it depends on how much the user uses their phone and whether Android felt the need to kick the activity out of RAM

Ahh okay, so basically it would be best to create a database just in case

if the activity is still around, it would show whatever the activity had before

that would be my recommendation, yes, unless the data set is the size of Mount Rushmore

and here I thought the opinion you wanted was my pick for the NFC Championship Game

Lol, well, since we have you here...

(Packers, in honor of my namesake, the president/CEO over there)

Well... you can't be right about everything I suppose ;)

oh, no, Mark Murphy is definitely the president/CEO of the Green Bay Packers

oh, wait, you mean on the game outcome...

Ok for the database, drop and create a new one with each update, or do the official update the database itself thing?

that would depend on the data, I suppose

my gut instinct is to upgrade the database and leave the data there

Ok, then I need to go learn how to correctly do that stuff. Thanks yet again.

ALTER TABLE, wherever possible

Any chapter I should be looking at?

fitz: chime in if you come up with a question, so you get in the rotation

I don't think I have ALTER TABLE anywhere, except probably the LunchList tutorials

onUpgrade() in SQLiteOpenHelper is covered in the Database chapter in the BCG to Android Development

Prasanna: you said you had another question?

Ok, LunchList is my favorite tutorial for learning stuff anyway. I have used it a lot in making everything I have tried.

So how would the service inform the widget that there is new data for it?

it wouldn't

it would use AppWidgetManager to update the RemoteViews

ok.

Can the background service store data a mysql database?

well, there is no MySQL on Android

if you mean SQLite, yes

if you mean a Web service that is backed by MySQL, yes

yes. sorry.

I mean sqlite on the android device

I basically was thinking of

storing the data that is downloaded by the background service

in a sqllite data base and making this data available to the AppWidgetManager as a content provider. Does this make sense

um, maybe

you implement an AppWidgetProvider

it gets called when the app widget is added to the home screen and removed from the home screen

and, if you use updatePeriodMillis, it will be called to update the RemoteViews

if you want that stuff to access the database (whether through a content provider or not), that's fine

AppWidgetManager is the class that actually sends the RemoteViews to the home screen

you call it from AppWidgetProvider or anything else that is updating the RemoteViews

AppWidgetManager, therefore, has no direct relationship with your database or content provider

ok. and the background service will be able to write to the sqllite db right?

yes, all components in your app can work with your SQLite datbaase

er, database

How to get a background service to wake up and do work after a certain time period?

AlarmManager

covered in the BCG to Advanced Android Development

(BTW, NetApex, since we have a small group, feel free to ask other questions if you have them)

ok. How to get a background service to run every time the phone is turned on?

set up a BroadcastReceiver to watch for BOOT_COMPLETED

also covered in the BCG to Advanced Android Development

I am good for the moment, although listening to his questions has me thinking about how to best make use of C2DM now.

NetApex: beyond what I have in the book, I haven't touched C2DM

("the book" being BCG to Advanced Android Development)

ok, I will go over what is in there and at least it will start me off

So, in general for a background service to download quite a bit of data that needs to be displayed on a widget, what would be a good high level architecture?

I cannot really answer that question

to put it another way, that's somewhat more involved than would really fit in a chat session

ok

Mark, I am going to head out. Thanks a lot for your help today!

see you later!

anyone have any questions?

Another off the cuff question...

Have you played with app engine?

if you mean Google App Engine, not much

I decided I didn't like the approach

I'd rather use Slicehost or Amazon Web Services

Really? You are the second person I have heard talk about Amazon instead

Never heard of Slicehost, but now I will have to have a look

Why do you prefer those two over GAE?

it's a virtual private server firm

NetApex - it sounds like your doing a bit of the same stuff I am - Google does not have an samples for Apps yet - drag - you find any good resources?

NetApex: both Amazon EC2 and Slicehost give you Linux environments to run what you want

you aren't limited to specific structures like GAE does

Hmm, interesting.

with GAE, you're adding coding headache to save administration headache

Yeah fitz, maybe we should talk sometime lol

I see

NetApex - ya e-mail me tomorrow when you can see if we can connect redacted

will do

thanks - Mark are all books updated now?

fitz: do you want that address in the transcript? if not, I'll try to remember to remove it before posting the transcript

to 2.3 I mean

fitz: BCG to Advanced Android Development needs an update to Android 2.3 -- should be ready by the end of the month

ya please remove e-mail address :)

the other two are updated

did not think of that :) long day

ok on books thanks - will have to pull them and do MORE READING

Hehe yeah same here, I am going to go over them again this weekend

ok thanks Mark I am bolting

and then there were two

I am pretty much out of questions for now until I read up some more on how to do some things

no, more like one and a half

I've had a rough day

Hehe

Will you be doing any training around the MidWest?

I have nothing scheduled

right now, I only do public training with Big Nerd Ranch (Atlanta) and Skills Matter (London)

other than maybe little one-day affairs

ChicagoAndroid ran a couple of those last year

I would be able to make those if you made it back to Chicago

Although hopefully it would be after May... saving up for the Google I/O

there's an Android training firm in Chicago trying to get some traction, so I suspect that ChicagoAndroid would prefer to help the local folk

ah, yes

surprised they haven't opened registration yet

Are you going there this year?

I am too.. been waiting since the 4th

it's on my calendar

Coolio, it would be cool to meet you

the challenge will be getting tickets

it sold out in a few weeks last year, as I recall

the day registration opens I will be all over it

it'll be interesting if the new Google CEO makes an appearance there

http://googlecode.blogspot.com/2010/06/sav… - Very first comment is exactly what I did that day. Started tossing money aside so that I would be ready when it was announced.

I always thought the CEO title was just a name when it came to Google though. Eric was the face, but I always felt he and Larry were running things.

oh, I agree

OTOH, I think Larry is a better fit for the I|O crowd

at least in terms of making an impression if he spoke

I don't think I have ever seen him speak

he and Sergey did a brief thing at the G1 launch that I caught on Webcast

otherwise, I haven't seen either of them, but I haven't exactly gone looking, either

oh wow, that was way back in the day

oh yeah

ok, well no need to keep you any longer I suppose

yeah, time to shut it down

only one chat next week due to travel

have a good night man, and thanks for the tips. Alrighty

have a pleasant evening!

You as well