Application programming interface ********************************* Service basics ============== Inside Connection Manager there exists one advanced interface to allow the user interface an easy access to networking details and user chosen preferences. This is the service list and interface. The basic idea is that Connection Manager maintains a single flat and sorted list of all available, preferred or previously used services. A service here can be either a Ethernet device, a WiFi network, a WiMAX service provider or a remote Bluetooth device (for example a mobile phone). This list of service is sorted by Connection Manager and there is no need for the user interface to implement its own sorting. User decisions will need to be done via Connection Manager and it is then responsible to update the order of services in this list. +---------------------------------------+ | Ethernet | +---------------------------------------+ | Bluetooth phone | +---------------------------------------+ | Guest (strength 90, none) | +---------------------------------------+ | My WiFi AP (strength 80, rsn) | +---------------------------------------+ | Clear WiMAX (strength 70) | +---------------------------------------+ | Other AP (strength 70, rsn) | +---------------------------------------+ | Friends AP (strength 70, wep) | +---------------------------------------+ | Other WiMAX (strength 50) | +---------------------------------------+ If none of the services has been used before the sorting order will be done with these priorities: 1. Ethernet (lower index numbers first) 2. Bluetooth (last used devices first) 3. GSM/UTMS/3G (if SIM card is present, activated and not roaming) 3. WiFi/WiMAX (signal strength first, then prefer WiMAX over WiFi, then more secure network first) The Ethernet devices are always sorted first since they are physically built into the system and will be always present. In cases they are switched off manually they will not be showing in this list. Since every Bluetooth device has to be configured/paired first, the user already made a choice here that these are important. Connection Manager will only show devices with PAN or DUN profile support. While Bluetooth devices do have a signal strength, it is mostly unknown since background scanning in Bluetooth is too expensive. The choice here is to sort the last used Bluetooth device before the others. The WiFi and WiMAX networks are treated equally since both provide signal strength information and networks closer in the proximity should be shown before others since it is more likely they are selected first. The signal strength value is normalized to 0-100 (effectively a percentage) and allows an easy sorting. If the signal strength is identical then the WiMAX network should be shown first since it is a licensed spectrum and more reliable. Also the number of WiMAX networks will be smaller than the number of WiFi since that operates in an unlicensed spectrum. WiFi networks with the same signal strength are then sorted by their security setting. WPA2 encrypted networks should be preferred over WPA/WEP and also unencrypted ones. After that they will be sorted by the SSID in alphabetical order. In the case the WiFi network uses WPS for setup and it is clearly detectable that a network waits for Connection Manager to connect to it (for example via a push-to-connect button press on the AP), then this network should be shown first before any other WiFi or WiMAX network. The reason here is that the user already made a choice via the access point. However this depends on technical details if it is possible to detect these situations. Service order ============= All unused services will have the internal order number of 0 and then will be sorted according to the rules above. For Bluetooth the user already made the decision to setup their device and by that means select it. However until the first connection attempt it might have been setup for total different reason (like audio usage) and thus it still counts as unused from a networking point of view. Selecting the "My WiFi AP" and successfully connecting to it makes it a favorite device and it will become an order number bigger than 0. All order numbers are internally. They are given only to service that are marked as favorite. For WiFi, WiMAX and Bluetooth a successful connection attempt makes these services automatically a favorite. For Ethernet the plugging of a cable makes it a favorite. Disconnecting from a network doesn't remove the favorite setting. It is a manual operation and is equal to users pressing delete/remove button. +---------------------------------------+ | My WiFi AP (strength 80, rsn) | order=1 - favorite=yes +---------------------------------------+ | Ethernet | order=0 +---------------------------------------+ | Guest (strength 90, none) | order=0 +---------------------------------------+ | | Ethernet is special here since the unplugging of the network cable will remove the favorite selection. +---------------------------------------+ | Ethernet with cable | order=1 - favorite=yes +---------------------------------------+ | Ethernet without cable | order=0 - favorite=no +---------------------------------------+ | Guest (strength 90, none) | order=0 +---------------------------------------+ | | This means that all services with an order > 0 have favorite=yes and all others have favorite=no setting. The favorite setting is exposed via a property over the service interface. As mentioned above, the order number is only used internally. Within Connection Manager many services can be connected at the same time and also have an IP assignment. However only one can have the default route. The service with the default route will always be sorted at the top of the list. +---------------------------------------+ | Ethernet | order=2 - connected=yes +---------------------------------------+ | My WiFi AP (strength 80, rsn) | order=1 - connected=yes +---------------------------------------+ | Guest (strength 90, none) | order=0 +---------------------------------------+ | | To change the default connection to your access point, the user needs to manually drag the access point service to the top of the list. Connection Manager will not take down default routes if there is no reason to do so. A working connection is considered top priority. +---------------------------------------+ | My WiFi AP (strength 80, rsn) | order=2 - connected=yes +---------------------------------------+ | Ethernet | order=1 - connected=yes +---------------------------------------+ | Guest (strength 90, none) | order=0 +---------------------------------------+ | | Another possible user interaction would be to unplug the Ethernet cable and in this case the favorite setting will be removed and the service falls back down in the list. +---------------------------------------+ | My WiFi AP (strength 80, rsn) | order=1 - connected=yes +---------------------------------------+ | Ethernet | order=0 +---------------------------------------+ | Guest (strength 90, none) | order=0 +---------------------------------------+ | | If the service on the top of the list changes the default route will be automatically adjusted as needed. The user can trigger this by disconnecting from a network, if the network becomes unavailable (out of range) or if the cable gets unplugged. As described above, the pure case of disconnecting from a network will not remove the favorite setting. So previously selected networks are still present and are sorted above all others. +---------------------------------------+ | Ethernet | order=2 - connected=yes +---------------------------------------+ | My WiFi AP (strength 80, rsn) | order=1 - connected=no +---------------------------------------+ | Guest (strength 90, none) | order=0 +---------------------------------------+ | | Unplugging the Ethernet cable will remove the favorite setting, but due to the basic ordering of services it will be at the top of the services with an order number of 0 (directly after all favorite services). +---------------------------------------+ | My WiFi AP (strength 80, rsn) | order=1 - connected=no +---------------------------------------+ | Ethernet | order=0 - connected=no +---------------------------------------+ | Guest (strength 90, none) | order=0 +---------------------------------------+ | | Service tweaks ============== The interfaces of Connection Manager will always export all services that are currently known. The Ethernet devices with no cable plugged are actually not included in this list. They will only show up once a carrier is detected. The service interface is not meant for basic device configuration task. So switching a device on and off (via RFKILL for example) should be done via the device interface. Due to limited screen size of small devices and the big amount of WiFi access points that are deployed right now it might be sensible to not show certain WiFi networks in the user interface. The choice to hide a WiFi network from the user interface should be purely done by the signal strength. The optimal cut-off value here still has to be determined, but in the end that is a user interface policy. Service naming ============== Every service will have a name property that allows the user interface to display them directly. All names will be already converted into UTF-8. It derives from the netork details. In case of WiFi this will be the SSID value. The SSID is a binary array and will be converted into printable form. Unprintable characters are replaced with spaces. For WiMAX networks the provider name like Clear or X-OHM will be used. This name either comes directly from the network itself or from a provisioning database of the WiMAX service. For Bluetooth the device alias is used. The alias is different since it can be overwritten by the user via the Bluetooth service. The identification is still done based on its address, but the display name might change. In most cases the alias is equal to the Bluetooth remote friendly name. For Ethernet device no name will be provided. The type property will indicate that this service is Ethernet and then it is up to the user interface to provide a proper localized name for it. Service states ============== Every service can have multiple states that indicate what is currently going on with it. The choice to have multiple states instead of a simple connected yes/no value comes from the fact that it is important to let the user interface name if a service is in process of connecting/disconnecting. The basic state of every service is "idle". This means that this service is not in use at all at the moment. It also is not attempting to connect or do anything else. The "association" state indicates that this service tries to establish a low-level connection to the network. For example associating/connecting with a WiFi access point. With the "configuration" state the service indicates that it is trying to retrieve/configure IP settings. The "ready" state signals a successful connected device. This doesn't mean it has the default route, but basic IP operations will succeed. With the "disconnect" state a service indicates that it is going to terminate the current connection and will return to the "idle" state. In addition a "failure" state indicates a wrong behavior. It is similar to the "idle" state since the service is not connected. +---------------+ | idle |<-------------------------------+ +---------------+ | | | | +-------------+ | +----------------------| failure | | | service.Connect() +-------------+ | V A | +---------------+ | | | association |-----------------+ | +---------------+ error | | | | | | success | | V | | +---------------+ | | | configuration |-----------------+ | +---------------+ error | | | | success | V | +---------------+ | | ready | | +---------------+ | | | | success | | | V | +---------------+ | | online |<----------------+ | +---------------+ | | | | | | service.Disconnect() | | V | | +---------------+ | | | disconnect |-----------------+ | +---------------+ error | | | +------------------------------------------+ The different states should no be used by the user interface to trigger advanced actions. The state transitions are provided for the sole purpose to give the user feedback on what is currently going on. Especially in cases where networks are flaky or DHCP servers take a long time these information are helpful for the user. Some services might require special authentication procedure like a web based confirmation. The LoginRequired property should be used to check for this. Application basics ================== All applications should use D-Bus to communicate with Connection Manager. The main entry point is the manager object. Currently the manager object is located at "/", but this might change to allow full namespacing of the API in the future. The manager interface is documented in manager-api.txt and contains a set of global properties and methods. A simple way to retrieve all global properties looks like this: bus = dbus.SystemBus() manager = dbus.Interface(bus.get_object("net.connman", "/"), "net.connman.Manager") properties = manager.GetProperties() Changing a global property is also pretty simple. For example enabling the so called offline mode (aka flight mode) it is enough to just set that property: manager.SetProperty("OfflineMode", dbus.Boolean(1)) The manager object contains references to profiles, devices, services and connections. All these references represent other interfaces that allow detailed control of Connection Manager. The profiles and devices interfaces are more for advanced features and most applications don't need them at all. The services are represented as a list of object paths. Every of these object paths contains a service interface. A service is a global collection for Ethernet devices, WiFi networks, Bluetooth services, WiMAX providers etc. and all these different types are treated equally. Every local Ethernet card will show up as exactly one service. WiFi networks will be grouped by SSID, mode and security setting. Bluetooth PAN and DUN service will show up per remote device. For WiMAX the provider name will be used for grouping different base stations and access providers. This creates a simple list that can be directly displayed to the users since these are the exact details users should care about. properties = manager.GetProperties() for path in properties["Services"]: service = dbus.Interface(bus.get_object("net.connman", path), "net.connman.Service") service_properties = service.GetProperties() The service interface is documented in service-api.txt and contains common properties valid for all services. It also contains method to connect or disconnect a specific service. This allows users to select a specific service. Connection Manager can also auto-connect services based on his policies or via external events (like plugging in an Ethernet cable). Connecting (or disconnecting) a specific service manually is as simple as just telling it to actually connect: service.Connect() or service.Disconnect() It is possible to connect multiple services if the underlying technology allows it. For example it would be possible to connect to a WiFi network and a Bluetooth service at the same time. Trying to connect to a second WiFi network with the same WiFi hardware would result in an automatic disconnect of the currently connected network. Connection Manager handles all of this for the applications in the background. Trying to connect an Ethernet service will result in an error if no cable is plugged in. All connection attempts can fail for one reason or another. Application should be able to handle such errors and will also be notified of changes via signals. In future versions Connection Manager will interact with an agent to confirm certain transactions with the user. This functionality is currently not implemented. To monitor the current status of a service the state property can be used. It gives detailed information about the current progress. properties = service.GetProperties() print properties["State"] All state changes are also sent via the PropertyChanged signal on the service interface. This allows asynchronous monitoring without having to poll Connection Manager for changes.