mobile app 与server通信的四种方式

Have you ever wondered how the information gets into the application installed in your mobile device, how it is updated, and how it is synchronized with your account in the web application on the desktop? If you think that this is a case of miracle then it is time to know the truth.

How is it possible to comprise the database of 1000GB (no current mobile device can handle such an amount of space) into an application weighting 50KB? Impossible?

Let’s take a real example. The database of the famous Facebook equals to 25TB and is stored on several servers. In other words, it can be translated as if the Facebook DB could be stored in about 3200 USB flash cards with capacity of 8GB (a standard size of your photo camera flash card). Only imagine this amount! And on the opposite end, we can see your mobile application for this social media that is only about 7MB.

So, what are the options of communication between your mobile device and a remote storage?

In fact, there are several ways how to do this.

Here are several possible variants among which to choose depending on the business goals.

1. Direct Connection（telnet/ssh）

The mobile application directly connects to the server database to get respond. To ensure the confidentiality the SSH or another encryption type can be used.

Features:

• Direct connection using standard telnet/ssh;
• User verification via simple login/password;
• UI commands converted to server commands.

Advantages:

• Simple;
• No additional costs on developing of the back-end applications;
• No additional costs on maintaining of the additional hardware.

Disadvantages:

- No scalability;

- Can’t have access to external servers or databases (cloud access);

- Has the only functionality of the standard telnet/ssh protocol.

2. Server-side application(socket)

The mobile application directly connects to the server -side application that is in simple words a software program running on a remote server.

Features:

• Direct connection to a server-side application;

• User verification via simple/secure login/password;

• UI commands converted to server application commands.

Advantages:

• Direct connection;
• Can use external resources (servers, databases) using in-app connection from the server side;
• No additional costs on maintaining of the additional hardware.

Disadvantages:

- Scaling is possible, but is time and effort consumable;
- More complex and has no built-in possibilities for using in a cloud infrastructure;
- Require developing of the back end application;
- Back end application should be placed on the controllable server.

3. Web application(HTTP传送数据报可以是http数据或者JSON、XML。最常用这种！！！)

The mobile application can communicate with the same web application to get information from it.

Features:

• Using of a web services via specialized API;
• User verification via simple/secure login/password;
• UI commands converted to API requests.

Advantages: