[aerogear-dev] [aerogear-android] DataManager API inconsistency + solution

[Summers Pittman]

On 01/08/2014 09:42 AM, Tadeas Kriz wrote:
>
> On 08 Jan 2014, at 15:30, Summers Pittman <supittma at redhat.com 
> <mailto:supittma at redhat.com>> wrote:
>
>> On 01/08/2014 05:51 AM, Tadeas Kriz wrote:
>>> Hey everyone,
>>>
>>> I've been recently going through the DataManager API in 
>>> aerogear-android. In this email, I'd like to suggest addiction of 
>>> two method (or possibly three) into the `Store<T>` interface. These 
>>> would be:
>>>
>>> ```java
>>> /**
>>>  * If store is open, it can be read or written to.
>>>  */
>>> boolean isOpen();
>>>
>>> /**
>>>  * Opens store in current thread (blocking).
>>>  */
>>> Store<T> open();
>>>
>>> /**
>>>  * Opens store in background thread and then callback#onSuccess is 
>>> called.
>>>  */
>>> void open(Callback<Store<T>> callback);
>>> ```
>> I think those are fine. Feel free to JIRA it up and Passos and I will
>> review.
>>>
>>>> From my point of view, this makes sense to be in the `Store<T>` so 
>>>> I can switch between stores easily during development with no need 
>>>> to change other code. Also, if `read` or `write` operations are 
>>>> done with closed store, there are two possible workflows. First one 
>>>> is, that I'd fail and throw an exception. Second (and for me a 
>>>> preferred one) is, that all those methods would internally check if 
>>>> the store is open and if not, they'd call the `open` method. This 
>>>> also leads me to another API change for `Store<T>`.
>>>
>>> ```java
>>> /**
>>>  * Reads all the data from the underlying storage system asynchronously.
>>>  */
>>> void readAll(Callback<Collection<T>> callback);
>>>
>>> /**
>>>  * Reads a specific object/record from the underlying storage system 
>>> asynchronously.
>>>  */
>>> void read(Serializable id, Callback<T> callback);
>>>
>>> /**
>>>  * Search for objects/records from the underlying storage system 
>>> asynchronously.
>>>  */
>>> void readWithFilter(ReadFilter filter, Callback<List<T>> callback);
>>>
>>> /**
>>>  * Saves the given object in the underlying storage system 
>>> asynchronously.
>>>  */
>>> void save(T item, Callback<Void> callback);
>>>
>>> /**
>>>  * Resets the entire storage system asynchronously.
>>>  */
>>> void reset(Callback<Void> callback);
>>>
>>> /**
>>>  * Removes a specific object/record from the underlying storage 
>>> system asynchronously.
>>>  */
>>> void remove(Serializable id, Callback<Void> callback);
>>>
>>> /**
>>>  * Checks if the storage system contains no stored elements 
>>> asynchronously.
>>>  */
>>> void isEmpty(Callback<Boolean> callback);
>>> ```
>>>
>>> That's right, async methods for easy access to the storage from 
>>> background thread, without the pain of writing it myself (for 
>>> example, it makes no sense if I want to just call `store.save(..)` 
>>> and I'd have to write all the `AsyncTask` boilerplate).
>>>
>>> So, what do you think?
>>
>> I would rather throw an exception than open a database when you call
>> read and friends. That way a developer doesn't accidentally open a
>> database he meant to be closed. I don't have that strong of a feeling on
>> that point one way or another however.
>
> That's right, it's probably less error prone in scenarios when you 
> want the store closed.
>
>>
>> My stronger feeling is on adding callbacks to the stores methods. I
>> prefer for the Store to be synchronous and Pipes to be asynchronous. We
>> could add a StorePipe to our PypeTipes which may solve some of the 
>> headache.
>>
>
> Would "void open(Callback<Store<T>> callback);" make sense then? I 
> mean, that would add another inconsistency in the API, as one method 
> would be async and the rest would be only synchronous, wouldn't it?
True.  The reason for the exception here was that opening a SQL store or 
an encrypted store COULD take significant amount of time. For in Memory 
data stores this is instant of course.
>
>> Passos, wdyt?
>>
>>
>>>
>>> PS: You can find the whole text with highlighted syntax here:
>>>
>>> ---
>>> Tadeas Kriz
>>> tkriz at redhat.com <mailto:tkriz at redhat.com>
>>>
>>>
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>>> aerogear-dev at lists.jboss.org <mailto:aerogear-dev at lists.jboss.org>
>>> https://lists.jboss.org/mailman/listinfo/aerogear-dev
>>
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>
>
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