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SMEG Navigation Interface

1 AIM OF THE DOCUMENT

This document starts from the necessity to explain better the SMEG navigation module architecture.

This new architecture was originally defined for the first time during the SMEG march WorkShop.

The main goal of the wokshop was to redefine the previous module architecture in function of the new HMI development and of the fact that this new HMI will refer to the under BCM module through the DBUS channel information and through the SQL-lite database. In that place was also imposed the max data size each API could sent over the DBUS channel, and it was 1 Kbyte. All the other information not fitting this requirement was requested to excanche through the SQL-lite database.

The imposed limit over the DBUS was satisfied, in the case of Navigation module, sending the mass data through the UNIX SOCKET. This solution was agreed by Navigation team members and System-1 architect.

The problem didn’t regarded only the number of byte sent with each API, but also the API frequency invocation.

The navigation team exteemed the max frequency, looking at the already developed systems, in 300 APIs per second. It happens typically when the HMI must show a list of cities or roads or POI and the HMI user hasn’t introduced to many character in the filter.

To workaround this type of problem, has been decided to develop and public new APIs, in substitution or in additions, that in only one shot returns to the client the complete information list.

The DBUS / SQL-lite solution forecast server put the necessary data in the database (with SELECT and INSERT), while the client extract them (with SELECT and DELETE commands).

It effectively can avoid sending small or mass data over the DBUS channel.

For sure the SQL-lite solution could allow reducing, in remarkable mode, the publiced API numbers of the Navigation DBus interface. Many specialized API could be substituted with search command: “SELECT + SearchKey”.

The use of SQL database, as communication channel, for the Navigation module has many and remarkable contrary indication: