I am more or less convinced that it is possible to write my own code, inspecting the JSON and creating an object based on that.
But I am hoping that I have missed some part of the documentation, cause it would be nice to have a method such as ParseObject.create(JSON) in Android.
The scenario is that I push changes in server data out to relevant clients. The push is send directly from Cloud Code in afterSave.
Currently I just notify that a change has been made in a specific class, then the client reacts by fetching all the objects in that class and update the Local Datastore accordingly.
This is not very efficient so it would be nice to be able to simply send the updated object directly using the push and then pin it on the client. Completely avoiding the extra work from fetching and updating all the objects.
I know this question is quite old but I think there is a beginning of solution in this github thread: since the SDK is open source, we can see that they've a not-open method for that.
I had the same issue and I forked the SDK (and did a bit of git and Gradle! :) ) and it is working pretty well yet! (I wanted to send encrypted ParseObject from CloudCode).
And I had chance because someone did the job I wanted to do on this commit (ok that was not so much!) so it means that you can (kind of) trust the hack!
Hope it helps
Related
Closed. This question needs to be more focused. It is not currently accepting answers.
Want to improve this question? Update the question so it focuses on one problem only by editing this post.
Closed 5 years ago.
Improve this question
I want to sync data (such as db record, media) between an Android App and a Server. If you've seen Evernote or similar Applications, you certainly understand what I mean.
I have some question (imagine we want to sync DB records):
Every user has a part of server space for himself (such as Evernote or Dropbox). Maybe the user creates new records by cellphone and creates new records in server. How can I match these records together? If there are records with same ID What algorithms do you suggest me?
Except JSON, Are there any way for send data between cellphone device and server?
If SyncAdapter and ContentProvider can solve my problems, please explain exactly for me. (If you could offer some samples or tutorials to me OR Any advice or keywords to help broaden/guide my search would be appreciated as well).
I'll try to answer all your questions by addressing the larger question: How can I sync data between a webserver and an android app?
Syncing data between your webserver and an android app requires a couple of different components on your android device.
Persistent Storage:
This is how your phone actually stores the data it receives from the webserver. One possible method for accomplishing this is writing your own custom ContentProvider backed by a Sqlite database. A decent tutorial for a content provider can be found here: http://thinkandroid.wordpress.com/2010/01/13/writing-your-own-contentprovider/
A ContentProvider defines a consistent interface to interact with your stored data. It could also allow other applications to interact with your data if you wanted. Behind your ContentProvider could be a Sqlite database, a Cache, or any arbitrary storage mechanism.
While I would certainly recommend using a ContentProvider with a Sqlite database you could use any java based storage mechanism you wanted.
Data Interchange Format:
This is the format you use to send the data between your webserver and your android app. The two most popular formats these days are XML and JSON. When choosing your format, you should think about what sort of serialization libraries are available. I know off-hand that there's a fantastic library for json serialization called gson: https://github.com/google/gson, although I'm sure similar libraries exist for XML.
Synchronization Service
You'll want some sort of asynchronous task which can get new data from your server and refresh the mobile content to reflect the content of the server. You'll also want to notify the server whenever you make local changes to content and want to reflect those changes. Android provides the SyncAdapter pattern as a way to easily solve this pattern. You'll need to register user accounts, and then Android will perform lots of magic for you, and allow you to automatically sync. Here's a good tutorial: http://www.c99.org/2010/01/23/writing-an-android-sync-provider-part-1/
As for how you identify if the records are the same, typically you'll create items with a unique id which you store both on the android device and the server. You can use that to make sure you're referring to the same reference. Furthermore, you can store column attributes like "updated_at" to make sure that you're always getting the freshest data, or you don't accidentally write over newly written data.
If we think about today, accepted answer is too old. As we know that we have many new libraries which can help you to make this types of application.
You should learn following topics that will helps you surely:
SyncAdapter: The sync adapter component in your app encapsulates the code for the tasks that transfer data between the device and a server. Based on the scheduling and triggers you provide in your app, the sync adapter framework runs the code in the sync adapter component.
Realm: Realm is a mobile database: a replacement for SQLite & Core Data.
Retrofit Type-safe HTTP client for Android and Java by Square, Inc. Must Learn a-smart-way-to-use-retrofit
And your sync logic for database like: How to sync SQLite database on Android phone with MySQL database on server?
Best Luck to all new learner. :)
If you write this yourself these are some of the points to keep in mind
Proper authentication between the device and the Sync Server
A sync protocol between the device and the server. It will usually go in 3 phases, authentication, data exchange, status exchange (which operations worked and which failed)
Pick your payload format. I suggest SyncML based XML mixed with JSON based format to represent the actual data. So SyncML for the protocol, and JSON for the actual data being exchanged. Using JSON Array while manipulating the data is always preferred as it is easy to access data using JSON Array.
Keeping track of data changes on both client and server. You can maintain a changelog of ids that change and pick them up during a sync session. Also, clear the changelog as the objects are successfully synchronized. You can also use a boolean variable to confirm the synchronization status, i.e. last time of sync. It will be helpful for end users to identify the time when last sync is done.
Need to have a way to communicate from the server to the device to start a sync session as data changes on the server. You can use C2DM or write your own persistent tcp based communication. The tcp approach is a lot seamless
A way to replicate data changes across multiple devices
And last but not the least, a way to detect and handle conflicts
Hope this helps as a good starting point.
#Grantismo provides a great explanation on the overall. If you wish to know who people are actually doing this things i suggest you to take a look at how google did for the Google IO App of 2014 (it's always worth taking a deep look at the source code of these apps that they release. There's a lot to learn from there).
Here's a blog post about it: http://android-developers.blogspot.com.br/2014/09/conference-data-sync-gcm-google-io.html
Essentially, on the application side: GCM for signalling, Sync Adapter for data fetching and talking properly with Content Provider that will make things persistent (yeah, it isolates the DB from direct access from other parts of the app).
Also, if you wish to take a look at the 2015's code: https://github.com/google/iosched
For example, you want to sync table todoTable from MySql to Sqlite
First, create one column name version (type INT) in todoTable for both Sqlite and MySql
Second, create a table name database_version with one column name currentVersion(INT)
In MySql, when you add a new item to todoTable or update item, you must upgrade the version of this item by +1 and also upgrade the currentVersion
In Android, when you want to sync (by manual press sync button or a service run with period time):
You will send the request with the Sqlite currentVersion (currently it is 1) to server.
Then in server, you find what item in MySql have version value greater than Sqlite currentVersion(1) then response to Android (in this example the item 3 with version 2 will response to Android)
In SQLite, you will add or update new item to todoTable and upgrade the currentVersion
Look at parseplatform.org.
it's opensource project.
(As well as you can go for commercial package available at back4app.com.)
It is a very straight forward and user friendly server side database service that gives a great android client side API
one way to accomplish this to have a server side application that waits for the data. The data can be sent using HttpRequest objects in Java or you can write your own TCP/IP data transfer utility. Data can be sent using JSON format or any other format that you think is suitable. Also data can be encrypted before sending to server if it contains sensitive information. All Server application have to do is just wait for HttpRequests to come in and parse the data and store it anywhere you want.
I would suggest using a binary webservice protocol similar to Hessian. It works very well and they do have a android implementation. It might be a little heavy but depends on the application you are building. Hope this helps.
#Grantismo gives a great overview of Android sync components.
SyncManagerAndroid library provides a simple 2-way sync implementation to plug into the Android Sync framework (AbstractThreadedSyncAdapter.OnPerformSync).
https://github.com/sschendel/SyncManagerAndroid
I am interested in making android app like crickbuzz that will fetch live content from server and also there is option of like and comment for users for feedback. So, can anyone tell that how to implement this i.e (how to fetch data from server) how that data will fit in app(confused about this how data get fit in instagram app means profile, home, search tab)
thanks
I suggest you check out this links
Android, PHP & MySQL
Fetch Data From Server
Ok, let's break it down:
The data is obtained from the server using http requests. It is usually received in the form of JSON String, basically a ordered, human-readable data format which is easy to read and parse.
On the app side, you need to implement the layout, which is done in xml and Java. You also need some logic which will obtain the data with the aforementioned requests, parse it, turn into Java Objects and put everything into the layout.
The process is not really complex, could be completed by a single person, but you will need experience, time and good architectural decisions.
If this is your first time with Android app programming, do some tutorials (especially ones that cover networking), learn some libraries (Volley, Retrofit, org.json, RXJava, Picasso will be really useful for what you ask about) and code several small apps from start to end. After that you may be ready to tackle the app you described :-)
I am developing in iOS with Parse. My app required offline operation, so I had developed my own solution. However, Parse's introduction of the LocalDataStore obviates the need for my own solution. Since this is not released in iOS yet, I can only rely on documentation to prepare for this. I asked these questions on the Parse forum a week ago and the questions have been completely ignored by Parse. Can anyone answer these via experience with the Android version?
1) Objects pointed to by pointers and PFRelations will be pinned along with the pinned object. (That's correct, right?) Will PFFiles be pinned along with the object? Will the file data be locally available?
2) When a pinned object is modified, you have to SaveEventually it to push the changes to the Server, right? Does a Save on a pinned object save locally? Or does it do an "on-line" save?
3) When changes occur elsewhere to a pinned object, how do those changes get propagated to the pinned object in the LocalDataStore? Does the programmer have to explicit fetch the changes, or will it happen automatically?
4) Does the concept of logging in apply to the LDS? Do the ACLs operate in the LDS? Or does the local code have access to all objects in the LDS?
-Bob
I can give a basic answer from the Android side, but keep in mind the details may change as the Parse.com iOS version of LDS is released. My answers below come direct from the API docs are are bolded where I quote directly.
Let's go point by point:
1) Objects pointed to by pointers and PFRelations will be pinned along with the pinned object. (That's correct, right?) Will PFFiles be pinned along with the object? Will the file data be locally available?
Yes. From the Android docs: "Pinning a ParseObject is recursive, just like saving, so any objects that are pointed to by the one you are pinning will also be pinned."
2) When a pinned object is modified, you have to SaveEventually it to push the changes to the Server, right? Does a Save on a pinned object save locally? Or does it do an "on-line" save?
Again, from the Android docs this appears to be Yes. "Once you've saved some changes locally, there are a few different ways you can save those changes back to Parse over the network. The easiest way to do this is with saveEventually. When you call saveEventually on a ParseObject, it will be pinned until it can be saved. The SDK will make sure to save the object the next time the network is available."
3) When changes occur elsewhere to a pinned object, how do those changes get propagated to the pinned object in the LocalDataStore? Does the programmer have to explicit fetch the changes, or will it happen automatically?
The Android docs are pretty quiet about this process, but it's a safe bet you will have to query the server to synchronize the local datastore, the same way you do now when you have a local instance of an object after a query. That's all all the local data store is - a very persistent version of queried data.
4) Does the concept of logging in apply to the LDS? Do the ACLs operate in the LDS? Or does the local code have access to all objects in the LDS?
Logging in still applies, as does ACLs, as far as I can tell. The object permissions are still required for the local data. I haven't confirmed this with a test project in Eclipse, but the docs allude to this being the case.
A final note: The CEO of Parse, Ilya Sukhar, weighed in on the Google Group 3 days ago saying the iOS LDS is definitely on it's way. Here's hoping it's soon!
Closed. This question needs to be more focused. It is not currently accepting answers.
Want to improve this question? Update the question so it focuses on one problem only by editing this post.
Closed 5 years ago.
Improve this question
I want to sync data (such as db record, media) between an Android App and a Server. If you've seen Evernote or similar Applications, you certainly understand what I mean.
I have some question (imagine we want to sync DB records):
Every user has a part of server space for himself (such as Evernote or Dropbox). Maybe the user creates new records by cellphone and creates new records in server. How can I match these records together? If there are records with same ID What algorithms do you suggest me?
Except JSON, Are there any way for send data between cellphone device and server?
If SyncAdapter and ContentProvider can solve my problems, please explain exactly for me. (If you could offer some samples or tutorials to me OR Any advice or keywords to help broaden/guide my search would be appreciated as well).
I'll try to answer all your questions by addressing the larger question: How can I sync data between a webserver and an android app?
Syncing data between your webserver and an android app requires a couple of different components on your android device.
Persistent Storage:
This is how your phone actually stores the data it receives from the webserver. One possible method for accomplishing this is writing your own custom ContentProvider backed by a Sqlite database. A decent tutorial for a content provider can be found here: http://thinkandroid.wordpress.com/2010/01/13/writing-your-own-contentprovider/
A ContentProvider defines a consistent interface to interact with your stored data. It could also allow other applications to interact with your data if you wanted. Behind your ContentProvider could be a Sqlite database, a Cache, or any arbitrary storage mechanism.
While I would certainly recommend using a ContentProvider with a Sqlite database you could use any java based storage mechanism you wanted.
Data Interchange Format:
This is the format you use to send the data between your webserver and your android app. The two most popular formats these days are XML and JSON. When choosing your format, you should think about what sort of serialization libraries are available. I know off-hand that there's a fantastic library for json serialization called gson: https://github.com/google/gson, although I'm sure similar libraries exist for XML.
Synchronization Service
You'll want some sort of asynchronous task which can get new data from your server and refresh the mobile content to reflect the content of the server. You'll also want to notify the server whenever you make local changes to content and want to reflect those changes. Android provides the SyncAdapter pattern as a way to easily solve this pattern. You'll need to register user accounts, and then Android will perform lots of magic for you, and allow you to automatically sync. Here's a good tutorial: http://www.c99.org/2010/01/23/writing-an-android-sync-provider-part-1/
As for how you identify if the records are the same, typically you'll create items with a unique id which you store both on the android device and the server. You can use that to make sure you're referring to the same reference. Furthermore, you can store column attributes like "updated_at" to make sure that you're always getting the freshest data, or you don't accidentally write over newly written data.
If we think about today, accepted answer is too old. As we know that we have many new libraries which can help you to make this types of application.
You should learn following topics that will helps you surely:
SyncAdapter: The sync adapter component in your app encapsulates the code for the tasks that transfer data between the device and a server. Based on the scheduling and triggers you provide in your app, the sync adapter framework runs the code in the sync adapter component.
Realm: Realm is a mobile database: a replacement for SQLite & Core Data.
Retrofit Type-safe HTTP client for Android and Java by Square, Inc. Must Learn a-smart-way-to-use-retrofit
And your sync logic for database like: How to sync SQLite database on Android phone with MySQL database on server?
Best Luck to all new learner. :)
If you write this yourself these are some of the points to keep in mind
Proper authentication between the device and the Sync Server
A sync protocol between the device and the server. It will usually go in 3 phases, authentication, data exchange, status exchange (which operations worked and which failed)
Pick your payload format. I suggest SyncML based XML mixed with JSON based format to represent the actual data. So SyncML for the protocol, and JSON for the actual data being exchanged. Using JSON Array while manipulating the data is always preferred as it is easy to access data using JSON Array.
Keeping track of data changes on both client and server. You can maintain a changelog of ids that change and pick them up during a sync session. Also, clear the changelog as the objects are successfully synchronized. You can also use a boolean variable to confirm the synchronization status, i.e. last time of sync. It will be helpful for end users to identify the time when last sync is done.
Need to have a way to communicate from the server to the device to start a sync session as data changes on the server. You can use C2DM or write your own persistent tcp based communication. The tcp approach is a lot seamless
A way to replicate data changes across multiple devices
And last but not the least, a way to detect and handle conflicts
Hope this helps as a good starting point.
#Grantismo provides a great explanation on the overall. If you wish to know who people are actually doing this things i suggest you to take a look at how google did for the Google IO App of 2014 (it's always worth taking a deep look at the source code of these apps that they release. There's a lot to learn from there).
Here's a blog post about it: http://android-developers.blogspot.com.br/2014/09/conference-data-sync-gcm-google-io.html
Essentially, on the application side: GCM for signalling, Sync Adapter for data fetching and talking properly with Content Provider that will make things persistent (yeah, it isolates the DB from direct access from other parts of the app).
Also, if you wish to take a look at the 2015's code: https://github.com/google/iosched
For example, you want to sync table todoTable from MySql to Sqlite
First, create one column name version (type INT) in todoTable for both Sqlite and MySql
Second, create a table name database_version with one column name currentVersion(INT)
In MySql, when you add a new item to todoTable or update item, you must upgrade the version of this item by +1 and also upgrade the currentVersion
In Android, when you want to sync (by manual press sync button or a service run with period time):
You will send the request with the Sqlite currentVersion (currently it is 1) to server.
Then in server, you find what item in MySql have version value greater than Sqlite currentVersion(1) then response to Android (in this example the item 3 with version 2 will response to Android)
In SQLite, you will add or update new item to todoTable and upgrade the currentVersion
Look at parseplatform.org.
it's opensource project.
(As well as you can go for commercial package available at back4app.com.)
It is a very straight forward and user friendly server side database service that gives a great android client side API
one way to accomplish this to have a server side application that waits for the data. The data can be sent using HttpRequest objects in Java or you can write your own TCP/IP data transfer utility. Data can be sent using JSON format or any other format that you think is suitable. Also data can be encrypted before sending to server if it contains sensitive information. All Server application have to do is just wait for HttpRequests to come in and parse the data and store it anywhere you want.
I would suggest using a binary webservice protocol similar to Hessian. It works very well and they do have a android implementation. It might be a little heavy but depends on the application you are building. Hope this helps.
#Grantismo gives a great overview of Android sync components.
SyncManagerAndroid library provides a simple 2-way sync implementation to plug into the Android Sync framework (AbstractThreadedSyncAdapter.OnPerformSync).
https://github.com/sschendel/SyncManagerAndroid
I'd like to add the ability for my android app to save changes to data (stored in its SQLite database) to a web server. The upload will be via HTTP POST, using JSON in the body of the request to describe the changes.
I'm wondering if I should use an android Service for this. I'd like the user to be able to continue interacting with the app while it's generating the JSON, making the call to the server, and waiting for the server to complete its work and return a response.
Thanks much!
Even better would be an IntentService
Edit: Now that the compatibility package is out I think the new Loader class may be the best option, possibly using the ASyncTask version or a variation of it.
Yes it is a very good idea to move all the webservice code into a service. The Google IO talk Developing Android REST client applications talks about many reasons why this is a good idea. It also covers other important considerations which relate to your problem which is effectively syncing your database to the cloud.