The following is the first few sections of a chapter from The Busy Coder's Guide to Android Development, plus headings for the remaining major sections, to give you an idea about the content of the chapter.
Backing up your PC used to be essential. To some extent, it still is, but as more and more stuff moves to “the cloud”, local machine backups become less and less important.
Backing up mobile devices historically has been an afterthought, as a lot of what people use these devices for are gateways to Internet-hosted content and services. However, as more and more stuff becomes local to the device — for disconnected operation, for example — the greater the need for backing up that local data.
Android does not have a full-device backup as part of the OS. It does have some hooks that Google advertises as being “backup”, but IT professionals would not consider Google’s definition to match their own for “backup”. And, what hooks there are exist at the level of an app, not the device, providing opportunity — and requirements — for developers to tailor what gets backed up and, to a lesser extent, how it gets backed up.
This chapter will explore the steps to back up your app’s data, with and without Google’s assistance.
Understanding this chapter requires that you have read the core chapters, particularly the ones on file access and Internet access.
Having read the chapters on SSL and SQLCipher for Android are not required but may prove to be useful background for some of the side topics in this chapter.
One key concept when it comes to backups is what, exactly, we are backing up. The general rule is that you focus your backup regimen on the “system of record”. This is the one and only system that has the master copy of the data. While it may be one “system”, that “system” may be rather complex (e.g., cluster of database servers). However, anything else outside of that system — such as clients for those servers — are not part of the system of record. While they may have some data that is also held by the system of record, that data is considered to be a cached local copy; the system of record has the “real” copy of the data.
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