Workflow based Design for Blending Services over IP Multimedia
Subsystems (IMS) with Service Capability Interaction Manager
Rohan Pascal Savio Goveas
1
, Raghavendra Sunku
1
, Madan Pande
2
and Debabrata Das
2
1
CMS, Hewlett Packard, Mahadevpura, Bangalore-560048, India.
{goveasr, sunku}@hp.com
2
International Institute of Information Technology-Bangalore,
Electronic City, Bangalore-560100, India.
{mpande, ddas}@iiitb.ac.in
Abstract— Dynamic blended services represent a complex
activity specified by composing multiple service enablers based
on the user contextual data and operator defined rules associated
with single session. Telecom service providers are envisioning a
need for creating and introducing such dynamically blended
services in IP Multimedia Subsystem (IMS) networks with a
quick turnaround time. Service developing languages for
representing the service logic of dynamic blended services should
provide various features like readability, usability, extensibility
and state transition capabilities. Also the service execution
environment should support chaining mechanism, policy
enforcement, data federation and provide context awareness.
These features will help the application developers to rapidly
develop and host the blended services to meet the upcoming end
user requirements. The traditional approach, i.e., building
blended service logic from scratch using the C, C++, Java
programming languages may not address all the above challenges
efficiently. One of the potential approaches to address the above
challenges is workflow based modeling for the blended services.
We have implemented novel workflow based design architecture
to present a blending of services over IMS core network by using
JBoss jBPM (Java Business Process Management) engine at core
of our proposed centralized service capability interaction
manager (SCIM) architecture. The considered use case is
designed and implemented using jPDL (jBPM process
development language). We also integrated the Open-SIP-
Presence server and the Live555 Video streaming server with
proposed SCIM application server (AS). A prototype of a content
server implementation has been done which acts as a service
capability in the context of discussed use case. Furthermore, UCT
IMS Client has been enhanced to validate the proposed Use Case.
Keywords-SCIM; service blending; jBPM; jPDL;IMS;
I. INTRODUCTION
IMS based users may ask for intelligent services which may
invoke multiple application/services hosted at different servers.
These services may be dynamically invoked based on user and
network context (availability of particular user/device and
network type etc.). In such a scenario all the involved services
are invoked and dynamically blended in the context of the
single user session (the user will be able to receive one or
multiple services on single session based on the service logic
developed). This involves interaction between various service
capabilities and application servers in a controlled and secure
manner. Hence, a blended service represents a complex activity
specified by composing one or more service enablers. This
closely maps to a work flow in a business process terminology
[5]. Blended services can be either static or dynamic in nature.
The static blended service is invocation of service enablers in a
predefined order. Whereas the dynamic blended services are
more adaptive to characteristics of the network and user
context. Further blended services may inter-work with service
enablers that are spread across different boundaries which
involves lot of context switching and state transitions [2, 4].
The IMS-based telecom networks will experience a mass
proliferation of such blended services [2, 9]. These services
could be more complex and dynamic in nature comprising a
blend of IMS-telecom and Web 2.0.
Telecom Enterprises are focused on both the development
of such dynamic blended services, as well as infrastructures for
supporting the design, development, and delivery of such
services. In particular, one of the main results of this effort has
been the introduction of service capability interaction manager
(SCIM) by 3GPP. SCIM in IMS network is an intelligent node
which enables to combine service logic across multiple
application servers there by delivering blended services to end
users.
Quick roll out of blended services is a real challenge and
will be a major differentiator for service providers to acquire a
large customer base. Since blended services chain multiple
service capabilities; policy enforcement would be an interesting
aspect from a service provider perspective. Simpler ways of
modifying and customizing of such blended services is also of
interest to service providers to rapidly adapt to the changing
market dynamics.
To address the issues involved a good amount of research
and prototype implementation work is going on in the scientific
community. As part of this, in [1] the authors make a
comparative study between three different programming
languages for service composition. The languages authors’
chose are SIP Servlet, Java and BPEL (Business Process
Execution Language). Authors observe that Java is the best
programming language for service composition in terms of
development efforts. BPEL based approach is very time
consuming during service development and does not deliver a
good performance with respect to service execution in SIP
based environments. Performance wise [1] concludes that SIP
Servlet implementation has the best performance. But since
SIP Servlet deals with many details of the protocol layer, this
programming model is in the lowest level of abstraction among
the three models. Reference [1] gives an interesting conclusion
that BPEL based service composition is preferred when we
want to create new blended services using the existing service
capabilities which are exposed as Parlay X or Web Services
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