On Thursday, 2009-07-16, Simone Piccardi wrote: > Kevin Krammer wrote: > > On Monday, 2009-07-13, Simone Piccardi wrote: > >> What I do not understand is why a client should be depend on the > >> installation of the corresponding server. It seems to like requiring to > >> install apache to run firefox. > > > > Not quite, this is a different kind of server/client relation ship. > > This is a session runtime service, more like D-Bus clients depending on > > D-Bus. A part of the runtime infrastructure, essential functionality > > shared between applications through inter process communication. > > Probably that was not the right analogy, but... I still cannot think of > mysql-server as a "session runtime service". I was referring to the Akonadi server. It is unfortunate that it currently depends on the MySQL server (with patched for Postgres pending), but the embedded DB options investigated initially didn't provide the requirements (e.g. transactions, use in multi-threaded app). Hopefully future versions of them will so Akonadi can then default to one of them instead. > But also if akonadi was part of a KDE infrastructure, it should be clear > that people can have addressbook (like I do) in an LDAP server. That's > one of the supported sources for kaddressbook, so forcing me to use > akonadi (and to install mysql for this) just to look in an LDAP > directory cannot be a correct choice. That sounds a bit like the common misunderstanding that Akonadi would be some kind of PIM data server. Unfortunately the terminology "server" is often mixed up with the concept of "data source", so session servers are often referred to as services instead. So it is probably better to think of Akonadi as a service rather than a server, even if this is technically the very same thing. The main services provided by the Akonadi server are uniform access, change tracking and caching. Uniform access meaning that different types of PIM data can be accessed through the same mechanisms and independent from the data source. Change tracking meaning that clients will get notified when individual items change as opposed to polling passive data sources for changes or getting vague notifications like "there was some kind of change" (e.g. file change notification on a vcf file). Caching meaning that data remains available (depending on policies) even if the data source is not. E.g. data stored on a remote server when being offline. Of course, whether or not an application needs any of these services depends on the application's and users' respective use cases. E.g. a mail client without need for address book support and without need for local storage and with users who don't mind waiting for each message to be retreived every time it is accesses might not need any of the above things. Cheers, Kevin
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