1. Field of the Invention
This application relates to extending an application interface for future applications, and more specifically to tagging a Session Initiation Protocol (SIP) session on a mobile terminal to associate the SIP session with a specific application and SIP messages for the SIP session are associated with and routed to the specific application according to the tagging.
2. Description of the Prior Art
Mobile service providers are interested in adding new third party application services to those pre-defined in the Global System for Mobile Communications Association (GSMA) Rich Communication Services (RCS) specifications. The RCS enhanced (RCS e) specification provides a mechanism for discovering new services by defining a tag which third parties can place in the capability message to announce support for a new service. However, the GSMA specification does not provide a mechanism that allows third party applications to leverage existing protocol stacks to support these new services.
A mechanism that allows third party applications to leverage existing protocol stacks to support new services in a mobile terminal is disclosed.
The mechanism includes a method of associating Session Initiation Protocol (SIP) messages with a specific application running on different user terminals. The method comprises tagging a SIP session to associate the SIP session with the specific application and associating SIP messages for the SIP session with the specific application according to the tagging.
The method may further comprise tagging the SIP session to associate the SIP session with the specific application by modifying an existing element in a header of the SIP, tagging the SIP session to associate the SIP session with the specific application by adding a new element to a header of the SIP, tagging the SIP session to associate the SIP session with the specific application by adding a new method to the SIP protocol, tagging the SIP session to associate the SIP session with the specific application by adding a new element to Session Description Protocol (SDP) parameters negotiated by the SIP, tagging the SIP session to associate the SIP session with the specific application by modifying an existing element of SDP parameters when negotiating the SDP parameters of a SIP session wherein modifying the existing element of the SDP parameters negotiated by the SIP may comprise specifying the specific application as a session name when negotiating the SDP parameters of the SIP session, and/or by adding a new data or media type which is not one of pre-defined Rich Communication Services (RCS) data transactions by supplying additional parameters that describe the new data or media type in an SDP parameters section when initiating a new conduit or adding the new media data type to an existing conduit.
The method may further comprise utilizing a conduit manager to match SIP sessions to the specific application when there are multiple applications sharing a same SIP connection between the user terminals.
The method may further comprise modifying a legacy RCS application by adding a SIP session manager checking each SIP session to determine whether the SIP messages are intended for the legacy RCS application and routing the SIP messages intended for the legacy RCS application to said legacy RCS application and routing all remaining SIP messages to the conduit manager.
The method may further comprise adding a new data or media type which is not one of pre-defined RCS data transactions by supplying additional parameters that describe the new data or media type in an SDP parameters section when initiating a new conduit or adding the new media data type to an existing conduit.
The method may further comprise securing user terminals from unwanted RCS applications by each application holding a valid permission to access an RCS service.
These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.
A mechanism that allows third party applications to leverage existing protocol stacks to support new services is disclosed.
The requirements for such a mechanism should include the following:
Private SIP Stack
In one approach, every application has its own SIP stack. Every application registers its own SIP stack with the Internet Protocol Multimedia Subsystem (IMS) server. So if the terminal has a separate application for Voice over Internet Protocol (VoIP) and another one for Instant Messaging (IM), there would be two registrations for the terminal. Since service providers do not want to support IMS servers that support multiple registrations for a terminal, this approach will not be acceptable to most networks. This approach does not meet any of the first three requirements listed above.
Sharing SIP Stack
A GSMA working group has proposed a solution to GSMA. Their approach is to provide an API to give direct access to the SIP protocol. This meets the first requirement listed above, viz. allowing multiple applications to share the same SIP protocol. However, it fails to meet the other equally important requirements:
RCS defines a number of user activities (e.g. voice calling, IM). The RCS standard requires SIP to manage sessions that support these activities. Each activity has a set of pre-defined characteristics. SIP allows the session endpoints to negotiate these characteristics. For example, a video call requires that the end points negotiate audio and video stream characteristics, such as codec type and video frame rates.
A user (application) session (e.g. a video call, IM conversation) may consist of one or more SIP sessions. For a voice call, the user (application) session exactly coincides with the SIP session. When the SIP session ends, the call terminates. In IM, a user application session (conversation) may consist of many sequential and possibly overlapping SIP sessions.
Conduits
The communications between applications are often referred to as user or application sessions. In order to differentiate between a user session and a SIP session, the concept of virtual user (application) sessions between two endpoints as conduits is introduced.
Conduits manage communications between two specific applications. For example, a video calling conduit manages communications between two video calling applications. In order for each terminal receiving a conduit to know the intended application, each conduit contains information that identifies the intended application. This information is transported between conduit endpoints using the SIP protocol.
There are several ways for SIP to transport this information:
Any of the methods 1-5 mentioned above would provide the necessary application information. However, it is preferred that the approach selected will not require major changes to the SIP stack or its usage. The approach that requires the least amount of changes to existing protocol and application software is to modify an existing SDP parameter. Using this approach does not require any changes to the SIP stack or how it negotiates SDP parameters and is described in more detail later.
RCS Data Transactions using Conduits
Data transactions used by an RCS application can be classified as one of the following types.
Furthermore, RCS defines two types of data streaming: voice and video.
These standard transactions form the core applications in RCS.
These transactions are typically grouped into applications. For example, voice and video streaming are managed by a call manager application. An application managing these transactions on one terminal communicates with its peer on another terminal using a conduit.
Conduits can be extended to handle new applications and new types of data as it will be shown below.
Extending Conduits for New Applications
In current approaches to RCS applications, applications are defined by the types of data that they use. Using this approach, voice and video streaming are managed by a call manager application. As an illustration of a call manager application, short text messages are handled by a messaging application.
One problem with this approach is that new applications cannot use the same data transactions already used by existing applications. For example, a chess application cannot use short messages to communicate its moves. In the current model, the new application must create its own protocol and its own new data type, and separate registration with the RCS server. Alternatively, the new application has to be trusted to share all messages with the existing messaging application and have full access to the SIP stack for all other applications. The limitations of these two approaches are discussed in a previous section.
By using conduits, multiple applications can securely share the same data transactions. When necessary, even new data transactions can be added. The following sections describe how new applications can be added.
New Applications using Existing Data Transaction
New applications can share the same types of transactions by creating separate conduits. For example, a specific IM conduit is created for a chess game. In order for both sides of the conduit to know the intended application, the protocols underlying a conduit must communicate the intended application of the conduit.
A preferred method for communicating the intended application for the conduit, as discussed above, is to use an existing field in the SDP section of the SIP invitation: session name. Although the session name is a mandatory field, it is not currently used when negotiating the session description parameters of a SIP session. Existing applications, voice/video calling, IM, etc. could set the session name as they do now: filling it with a single space. New applications can set the session name with the tag used to perform a capability exchange. By tagging the SIP sessions this way, the conduit can direct SIP session data to the designated application.
There are already RCS specifications for exchanging capabilities. In order for media types to be shared between applications, one proposal for signaling that a session is associated with a particular application is outlined here. This is done by specifying the application as the session name.
The following example extends the media section by adding a new session name specifying the chess application.
If the application has a new stream data type, it can be added using a media section similar to the following.
This technique is illustrated by way of the following example.
An application developer wants to add a new chess game which requires simple short messages to be communicated between the two players to convey moves on a chessboard. The short messages used by the Messaging application for IM and SMS can be used to communicate the chess moves. However, the chess moves must not appear in the Messaging application. This can be achieved by creating a new conduit for the Chess application as follows.
When a user wants to initiate a chess session with a specific user, the application requests a conduit for the chess game. The protocol engine checks to see if that user's terminal supports a chess capability according to the GSMA RCS-e specification. If the remote terminal supports the chess capability, the protocol engine initiates a SIP session. The SDP description provides a session name that indicates that the SIP session is intended for the chess application.
The remote terminal receives the SIP invitation with the SDP session name of the chess application. The protocol engine on the remote terminal notifies listeners that an incoming chess conduit was received. The chess application receives the notification. It gives the user the option to accept the new conduit. If the user accepts the conduit, the application starts the game using short messages. Since these messages are designated for the chess game, they will not appear in the messaging application.
The chess application idea can further be extended to support voice conversations between terminals. All that is needed is to add the voice media to the conduit. The underlying protocol engine will negotiate the voice call. Since voice calling is already supported as a core RCS function, the voice engine can be managed in this conduit exactly the same way as a voice call.
Using the approach of using a conduit described above, all of the requirements listed above for a third party application are satisfied. In contrast, the GSMA working group proposal would fail to satisfy all but the first requirements listed earlier.
Earlier versions of the Android Operating System (OS) provided a method for sharing messages across different applications: the ordered broadcast technique. To use an ordered broadcast, each application registers to listen for a specific broadcast intent with a specific priority. When a message is available for this intent, each application is notified based on the request priority. Any application in the priority chain can consume the message and prevent lower priority applications from receiving the message. This turned out to be a fatal security defect. This defect is addressed in Android 4.4 (Kit Kat) which allows only one application to receive SMS messages. This application can be selected by the user. With this update, messages can no longer be shared by different applications.
Two call flows showing a successful and unsuccessful negotiation of a conduit are presented here for the Chess Game example. The following application flows assume that two clients are connected and registered.
Extending conduits for a New Data Transaction Type
In addition to sharing standard RCS data transactions between applications, an application can introduce a new type of data transaction that is not core to RCS. In this case, the application is required to manage this new type of stream. The conduit interface allows for a new data streaming media type with an extensible description of the stream. This can be accomplished by having the application supply additional parameters that describe the new media type for the SDP section. These parameters can be used when initiating a new conduit or adding the new mediadata type to an existing conduit.
When the remote party creates a new conduit that requires a description of the new streaming data type, the conduit reports the parameters to the application for this media.
This approach allows an application to support a new type of streaming data without the need to modify the protocol engine or access the SIP stack directly.
Supporting Multiple Applications with Conduits
The previous sections showed how conduits can be used to associate applications with different data types. When there are multiple applications sharing the same SIP connection, a conduit manager is added to match each conduit with the designated application, as shown in
In
Adding New Applications to a Legacy RCS Application
It has been shown above how multiple applications can be supported on a single SIP stack using Conduits. However, a large body of existing RCS applications and SIP applications already exist. One of the benefits of using Conduits is that legacy RCS and SIP applications (that do not use Conduits) can interoperate with applications that support conduits. Furthermore, new applications can be added to legacy SIP applications with minimal or no impact on the legacy applications. Details are provided in the following sections.
Interoperate with Legacy Applications (Without Conduit Support)
If the RCS application does not support conduits, the terminal is limited to the core RCS applications that it supports. When a remote terminal requests such a terminal to create a session with an unsupported application, capability discovery will reject such requests. However, a request from a legacy RCS application will be accepted and will function properly without any modification to the legacy application or underlying SIP stack.
Adding Conduit Support to a Legacy Application
In order to add conduit support to an existing application, the portion of the SIP application that manages SIP sessions can be modified to include a new SIP session manager. The session manager checks each session for the intended application. The session name would remain empty (unused) for legacy RCS data transactions. All sessions for the legacy RCS application would be routed by the SIP session manager to the RCS application. The remaining sessions would be routed to the Conduit Manager.
The left side of
With the addition a Conduit Manager 410, the original SIP session manager interfaces 412 are preserved. This means that the existing RCS application 450 will continue to work without any change. New applications 455, however, must use the software interfaces supplied by the conduit manager 410. This allows the new application 455 to share the same SIP stack 430 and registration as the legacy application.
Alternative to using conduits: If the application developer does not want to use conduits for new applications, the new applications can still share the same SIP connection and software stack with such applications. This is accomplished by providing an application interface that replaces the conduit features. The key conduit interoperability features that must be included for such an interface are:
Securing Conduits Under the Android OS
Android security is based on the following concepts.
Application developers use Android Services to perform long running background operations in the background. Since SIP sessions can be long running background operations, developers implement the SIP session manager and SIP stack either as an RCS service or as a native application accessed from an RCS service. Applications communicate with the SIP stack using the Android IBinder interface to the RCS service.
When applications use conduits, the conduits communicate with the RCS service. In order to secure conduits, the IBinder interface to the RCS service must be secured.
When a mobile terminal (phone) manufacturer (“OEM”) loads software on to the mobile terminal (phone,) all of the permitted applications and services are signed by the OEM key. If RCS applications and the RCS service are signed by the same key, the IBinder interface to the RCS service is easily secured. This can be done either by the RCS application and RCS service sharing the same process, or the RCS service checking that the communication is coming from the RCS application.
In order to provide third party applications (not signed by the OEM) access to conduits, the RCS service must be able to determine which application should have access to the service. A combination of permissions and certificate validations can be used to restrict applications to all or a subset of the conduit interface. The following sections describe different approaches to securing the conduit interface.
Android Permissions
The most basic approach is to require that each application hold a valid permission to access the RCS service. If the permission is marked as “dangerous”, the user determines whether to install the application and give it access to the RCS service.
Certificate Validation
Each application is signed by a certificate. The RCS service can check the certificate. If the certificate matches the OEM certificate, the application is granted full access to all interfaces supported by the RCS service. If the application does not the OEM certificate, access will be determined by security policy, which may grant restricted access to the third party application.
For higher level of security, the certificate could be checked against a known good list (white list) and against a known bad list (black list). If the certificate is not on either list, the security policy would dictate access. The white and black list should be updatable dynamically. An up-to-date list ensures that bad applications do not get access to the RCS service.
Application Validation
Because conduits contain the identity of the application, the conduit security could restrict conduits to specific applications. The security manager within the RCS service would need to manage which certificates can be associated with which types of conduits.
Implementation of Conduits
As previously stated, conduits manage communications between two specific applications. For each terminal receiving a conduit to know the intended application, each conduit contains information that identifies the intended application. This information is transported between conduit endpoints using the SIP protocol and there are several ways for SIP to transport this information. A preferred method of associating SIP messages with a specific application running on different user terminals includes tagging a SIP session to associate the SIP session with the specific application and associating SIP messages for the SIP session with the specific application according to the tagging.
The tagging of the SIP session can be accomplished in several ways such as, inter alia, by modifying an existing element in the SIP header, adding a new element to the SIP header, adding a new Method to the SIP protocol, adding a new element to the SDP parameters negotiated by SIP, and/or by modifying an existing SDP parameter.
STEP 810: Tag a SIP session to associate the SIP session with a specific application by modifying a header of the SIP.
STEPs 820, 830: Utilize a conduit manager to match SIP sessions to the specific application when there are multiple applications sharing a same SIP connection between the user terminals.
STEPs 840, 850: When using a legacy RCS application, modify the legacy RCS application by adding a SIP session manager checking each SIP session to determine whether the SIP messages are intended for the legacy RCS application and routing the SIP messages intended for the legacy RCS application to said legacy RCS application and routing all remaining SIP messages to the conduit manager.
STEP 860: Associate SIP messages for the SIP session with the specific application according to the tagging.
STEP 910: Tag a SIP session to associate the SIP session with a specific application by adding a new method to the SIP protocol.
STEPs 920, 930: Utilize a conduit manager to match SIP sessions to the specific application when there are multiple applications sharing a same SIP connection between the user terminals.
STEPs 940, 950: When using a legacy RCS application, modify the legacy RCS application by adding a SIP session manager checking each SIP session to determine whether the SIP messages are intended for the legacy RCS application and routing the SIP messages intended for the legacy RCS application to said legacy RCS application and routing all remaining SIP messages to the conduit manager.
STEP 960: Associate SIP messages for the SIP session with the specific application according to the tagging.
STEP 1010: Tag a SIP session to associate the SIP session with a specific application by modifying SDP parameters when negotiating the SDP parameters of a SIP session.
STEPs 1020, 1030: Utilize a conduit manager to match SIP sessions to the specific application when there are multiple applications sharing a same SIP connection between the user terminals.
STEPs 1040, 1050: When using a legacy RCS application, modify the legacy RCS application by adding a SIP session manager checking each SIP session to determine whether the SIP messages are intended for the legacy RCS application and routing the SIP messages intended for the legacy RCS application to said legacy RCS application and routing all remaining SIP messages to the conduit manager.
STEP 1060: Associate SIP messages for the SIP session with the specific application according to the tagging.
STEP 1110: Tag a SIP session to associate the SIP session with a specific application.
STEP 1120: Add a new data or media type which is not one of pre-defined RCS data transactions by supplying additional parameters that describe the new data or media type in a SDP parameters section when initiating a new conduit or adding the new media data type to an existing conduit.
STEP 1130: Associate SIP messages for the SIP session with the specific application according to the tagging.
STEP 1210: Tag a SIP session to associate the SIP session with a specific application.
STEP 1220: Secure user terminals from unwanted RCS applications by each application holding a valid permission to access an RCS service.
STEP 1230: Associate SIP messages for the SIP session with the specific application according to the tagging.
Any of the above flows 800-1200 may be implemented independently or in combination with any other flow (s) 800-1200 and/or any methods described herein according to design considerations without departing from the invention.
This document summarized a secure and developer friendly approach for extending RCS to support new applications. This approach leverages the core data transactions by allowing new applications to use the same data transactions without interfering with the existing applications. In addition, new types of data transactions can be supported without giving application access to low level protocols that can cause portability and security concerns. And existing applications and protocol stacks can easily be extended to use the techniques described above.
Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.
This application claim priority to U.S. Provisional Patent Application No. 61/900,357, filed Nov. 5, 2013, included herein by reference in its entirety.
Number | Date | Country | |
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61900357 | Nov 2013 | US |