如何使用Web服务？

Question

I would ask a semi-theorical question about web services and client-server architecture.

I have a server with a database with about 50 tables. This server holds even one table which contains information about users associated with the clients. Each client has associations with a subset of all data in db.

The defined architecture implies that each client (running on Android app) calling ,with a predefined frequency, a certain number of Web Services, fill the local database, creating a copy of all the tables residing on server sb, containing the only information related to the requesting client.

Furthermore, the data in db server side can change, so frequent synchronization is required.

Considering that the client application can be imaginated as a shop online application, so should be possible browsing through providers, articles, make a order,remove orders etc.

So, when I talk about fill the local database I mean store providers, articles, ...that is, all information realated to the requesting client.

Can make sense fill the local database with this information?

I think that is more reasonable call a web service only exactly when the information is required, and not store information in local db. So, synchronization is no more required.

Tall me what you think about ? thank you.

Answer 1

I know NOTHING about Android development, but have tons of experience with using web services and SOA.

In my experience, especially when the client device has limited storage and processing power, all the business logic and data logic should be in the web services, and the client app used only for display and calling those services. How you implement that is something that we can't answer for you. It's different on every project.

The only exception is when you absolutely have to have the app running while not connected. In that case, be sure you know your specific requirements, and be very dilligent to only persist at the client the data that you absoutely need , and only provide the business logic that you absolutely need while disconnected.

(This helps to keep security simpler as well - lost or stolen devices are one of the highest sources of data breaches, so the less potentially sensitive data on the device the better.)

I don't know if that's helpful, but I throught I'd throw it out there.

Answer 2

If your application is going to work only online, then YES. You don't need to worry to store the data into the database and retrieve it later. If your requirement that needs to support both online and offline, then you have to go withe the database.

You can run a service or Async task or Handlers to invoke the Webservice from the Android Application, that way your UI thread won't be blocked.

If your response is too big, then probably you have to think about middle tier, that way you can convert the SOAP response to JSON that would be easier for the device to process the response and network transmission is faster.

I believe based on your requirements, its good enough to support only online mode... Because the data might vary if the user is not using the app for two days and logs in back and show offline data that might be irrelevant