I'm doing an android application much like the gmail app for android. I can see the app is very fast and very responsive.
I'm sure gmail uses local caching for better performance. But I wonder how does gmail does the following use cases.
Lets say i login for first time and the app loads all email and put in sql lite or any other caching.
use case1
every time i delete or add a star it makes an asyncronous server req to server. this is fine.
use case 2.
how does the app get notified in case the user makes changes from another client. (from a browser).
To download the entire mails will be costly. Lets assume a case in which the user adds a star to a already cached email.
How can we implement the api in such a way that to get only updates which made from other clients. Updates like new email, deleted email, star added, etc. I'm considering the scenario when the user doesn't use the background sync.
This is been bothering me for a long time. Request you guys to let me know some tutorials or links to understand the secret behind the gmail app.
Why don't you look at the gmail web app. That will be using the same/similar design principals (gmail web app is also very fast for me). Then you can apply the same principals. With the web app you can look at the web requests using something like firebug with firefox. Under the Net tab it will show the json of what is being sent across the network. It will also show you the way the request was structured. You wont be able to see how they go about optimally returning the data, but that should be fairly trivial.
I would recommend for returning data that you do the following:
1) create a cache for the most recent page of emails.
2) Updates of new emails will be immediately prefetched into the cache.
3) setup a cache for the next page and previous page of emails.
Essentially what I am saying is:
1) You can look at googles web version which is very visible to plain snooping.
2) You can optimize based on statistical usage of how the user would want to see their emails. This can suggest cache improvements.
What you are asking for in terms of links is harder because your question relates to many general concepts and proriatary software.
Related
How can I show real time database changes in a flask website?
Like on_update and on_insert, the data will be pushed to the website for the user to see.
I want to get alert from an IOT device and insert it to the database and the users who are subbed to that device should get the real-time alerts.
So I thought
>IOT detects
>HTTP POST to database
>Flask App detects the database change
>push to clients on web app and android
I made a web app that queries the DB with flask-sqlalchemy but thats it, these are supposed to be real-time alerts! I'm so frustrated it's been a week. I am going nowhere and I feel so lost now.
>polling
>web sockets
>SSE
>flask sse
>use AJAX
>use JQUERY
HHHOOOOOWWWWW?????? Most of the examples are for chat apps, and I see NO method where you listen to database changes and send it to clients ;(
A very easy way to implement this is using an event SaaS like pusher.com. This should get you set up in no time. They have examples for many different languages and it should fit your need perfectly.
You mention that you see so many chat-apps as examples. This is pretty normal as they are almost the "hello-world" of event-based systems. And that's exactly what you are looking for. An event happens and you want to trigger something on that event.
For chats, the event is: "The user entered a message" and the triggered action is: "Display it to every connected/subscribed user".
Next to a hosted service like pusher.com, you can roll your own. All the required technology are free and open standards. You could use websockets or WebRTC for this. Websockets is easier but it's trickier if you have many open channels. On the other hand, WebRTC scales but it's a bit more complicated to set up. But you won't need video or audio which makes it easier.
You mention "polling" and I am not sure whether you mean "normal" polling or long-polling as in Comet. That is of course an option. It is the easiest solution, but not the cleanest.
SSE seems like a valid option as well. Although I have no personal experience with it yet. But it seems like it's designed for this use-case.
AJAX and jQuery are less related. AJAX is just an umbrella term for programming using XmlHTTPRequest and is used in all solutions mentioned above. jQuery is just a JS framework and is completely unrelated to the task.
long story short: All your mentioned options allow you to do this. I would suggest looking at pusher.com to get started. And their examples have exactly what you need. Their free plan is already really generous for personal projects. If your application outgrows the free plan you can either pay, or roll your own solution.
I have an android and iPhone app, and the apps are getting data
from my website based on some conditions they select on the app.
I created a secured url that is not open to the public (can't be find on our website) and using a hash code that I thought was secure enough. Something like the following
http://test.com/data/get_data.php?key=akl;sd8234
The extra conditions they select in the app will be append as query parameters to the same url.
Base on the condition, the php file will then out data in json format.
However, I discovered recently someone else create the exact same app and actually getting data from my server, and from the secret url that I created. The reason I know is because I change something on that secret get_data.php page and it reflected on their app.
I don't know who they get a hold to my url, is there a way to create a more secure way to pass the data from my web server to the app so others can't steal my data?
You should create an API with Basic Auth or OAuth. You can't rely on your URL because it can be caught in logs.
Check this course out
In addition to shayegh's answer, you need to understand that every endpoint that you access within your application is public by nature. Everyone can access your server's endpoint just as well as your mobile application (created by you) can. However, you can make your server's endpoint protected by adding authorization requirements on your endpoint.
Authorization
There are many authorization protocols out there, OAuth, OAuth2.0, Basic Auth (credentials like email and password), etc. All of these are just ways to grant anyone access to resources in your endpoint. Think of it as a lock on your home door, only someone with a key can go into your house and make a mess.
Please keep in mind that this is a very simplified version of what authorization protocols actually look like, how it actually secures the distribution of access keys/tokens, etc.
Additional questions and answers
I tried to generate log files from my android phone, and I can't seem to find the .php file from the log files. Is that possible for someone to decode the android app or the iphone app so that they can view my source code?
Answer: I would always assume that everything that is happening on client's side (mobile app, WebApp's front end, etc) is beyond my control. That means anyone can access, read, tweak my client applications. With that said, I would assume that it is indeed possible for someone to unravel your android / iPhone app (get the source code) to get your client side keys.
How would this (OAuth/basic) help? Surely the person creating the other app would just add the OAuth/basic auth as well, wouldn't they?
In order for that other person to access the protected endpoint they would need to have access to your access tokens of the original app. On top of that, they would need to do it fast because usually access tokens only lasts for a short period of time.
Will using Basic Auth or OAuth key works if they are able to see my code?
Yes and no, depending on your implementation, attackers might be able to unravel your app and somehow fetch user's credentials or tokens from bad practices.
I'm making a chess game,playable from both, an android device as well as a web browser.I will take input from user in a UI, & processing of that input-updating gamestate should happen at backend/application server.The response from server goes back to UI which displays the new gamestate.
Now my question is, what are possible options for application server I can explore to actually do this ?I'm not asking which is best or likewise....I just want to know what application servers are there which I can use to make my game.
I've made a similar application in netbeans using glassfish,but this time, I want an android device to be able to communicate with server too, so I'm confused how to approach this.
I've already tried google play services,but additional data about player,his statistics,etc needs to be stored client side,which I dont want.
Please suggest some alternatives.
The situation: I have many real life locations with specific information associated with them, and updated frequently. I am unsure of how to store this information for use in an android application.
My original thought was storing the data on some server/cloud source/database, reading from the server from each Activity in the app to make sure the info is up to date, and update the server with any changes that may or may not have been made.
For example: there are 200 people inside the library, one person leaves.
So we would read the number of people from the server, display this on the app, person leaves, subtract one, send the new number back to the server.
Would this be an incorrect approach? I'm fairly new to Android in general, and I really have no experience on how to approach this type of situation, what services to use, etc.
I would look into using Parse, its a pretty sweet way to power the backend, and their website is very detailed in explaining how to use it.
I am trying to write a little Android app for my daughter. The goal is to scan a book's bar code and pass the ISBN number to this website: http://www.arbookfind.com/default.aspx . The result will show if the book is part of the Accelerated Reader program and how many points the book is worth. I am trying to automate the part where the ISBN would need to be entered into the search field.
For simplicity's sake, and because I'm not a programmer, I am using MIT's App Inventor 2. I can now scan and get the ISBN but I will need to know how to format a URL to the website that will allow me to pass the ISBN to it's search page.
Is it possible to send a variable via the URL similar to index.php?myvar=testing&someothervar=somethingelse ? I've tried but perhaps I am not using the correct variable name or format for aspx. Is there an easy way to see what the variable name is in the aspx displayed page in my browser?
EDIT To clarify, I am not trying to scrape data and avoid showing ads from the site I am using to generate the results. I am wanting to pass the ISBN number to the page and have it search and display the resulting page in the phone's browser. I am also fine with a method that would populate the search field and the user would have to hit the search button if that can be accomplished easier.
I would recommend abandoning this route, as it is highly unlikely that the owners of this website will want you passing a query string to their site anyway, but rather they will most likely point you to an Application Programming Interface (API) that they provide, so that your program can connect to this service (free or paid, depending upon the company) and then you can request the book's details by providing the ISBN in the request.
There is no discovery mechanism for an .aspx page like there is for a web service to find out the names of things to pass. Even if you figure out what the name of the query string is that you could pass in for ISBN, you run the risk of the implementation being changed and your "application breaking". While this is also true of web service APIs, since APIs are the route the website providers want you to use, as opposed to screenscraping, then they generally inform their users of breaking changes or newer versions of the API via documentation.
From what I can see that page does not accept URL-variables for their search field the way google.com and other does. The page is generated through some sort of content management system (CMS) and it relies heavily on javascript to make things work. I tried doing a normal search there, and you have two issues you need to wriggle around.
First, the page redirects you to a page where you select if your a student, parent etc. It seems that it relies on some session cookie to remember the setting, but it times out pretty fast.
Second, the form uses javascript to trigger the search, and it appears to be done using AJAX, a method of using javascript to trigger actions on the server and displaying the results, without actually loading the page again. You might be able to get a hold of the javascript code used and re-engineer it for your purposes, and call that using HTTP POST and/or GET from your app, but it is a tricky path, and quite possibly not allowed by the company since you will be loading data from their site, without presenting their advertisements and thus be costing them money.