CONTEXT-AWARE SHARING CONTROL USING HYBRID ROLES

IN INTER-ENTERPRISE COLLABORATION

∗

Ahmad Kamran Malik and Schahram Dustdar

Distributed Systems Group, Institute of Information Systems, Vienna University of Technology, Vienna, Austria

Keywords:

Role-based access control, Context-aware systems, Context sharing, User-deﬁned roles, Inter-enterprise col-

laborations.

Abstract:

In enterprise-based collaborations, humans working in dynamic overlapping teams controlled by their respec-

tive enterprises, share personal context and team related context for accomplishment of their activities. Privacy

of personal context becomes vital in this scenario. Personal context contains information that user may not

want to share, for example, her current location and current activity. We propose a role-based dynamic sharing

control model which is owner centric and extends role-based access control model. We provide privacy of

owner’s personal context by separating it from team related context through the use of owner deﬁned roles.

Owner has full control of her personal data and is able to dynamically change her own access rules facing any

new situation. We describe a role-based dynamic sharing control architecture which makes use of enterprise-

deﬁned roles as well as owner-deﬁned roles for separating user context from team context. We evaluate our

approach by providing a real world scenario, its running example, and implementation as sharing control

messenger using Web services in Java.

1 INTRODUCTION

With the advancement of computing and distributed

systems technologies, new opportunities and chal-

lenges arise in the area of Collaborative Working En-

vironment (CWE), for example, (EU-Project, COIN).

Collaborative systems are used to handle collabora-

tive work of users as a team to support their activi-

ties. Members of dynamic overlapping teams can join

and leave team at any time and can be a member of

more than one team at a time. Requirements of these

systems are not only related to individual work of a

team member but also their collaborative team activi-

ties and working environment. Privacy of user context

and collaborations information in such team environ-

ments is an important concern.

Context plays an important role in dynamic collabo-

rative systems. Using dynamic nature of context, ac-

cess rule adaptation can be performed at runtime (Bal-

dauf et al., 2007). It is possible to dynamically adapt

behavior of a system by capturing current context of

context requester, provider, resources, and, environ-

ment. In dynamic collaborative systems ﬁne-grained

∗

This work is partially supported by the European Union

through the FP7-216256 project COIN.

level of sharing control is required in presence of dy-

namic entities in the system. Systems based on Role-

Based Access Control (RBAC) model (Sandhu et al.,

1996) have been used for controlling user’s access to

resources.

Owner should have control of her data and be able

to dynamically change her sharing rules facing any

new situation. In enterprise-based team environments

(Dustdar, 2004), enterprises create roles for their

users which deﬁne their access control policy. We use

owner-deﬁned roles in addition to enterprise-deﬁned

roles so that owner is able to share her personal con-

text with other collaborating users according to her

personal requirements. Owner-deﬁned roles are used

for temporary collaborations and are revoked after the

sharing requirement is complete. Role revocation is

based on static rules such as time duration and dy-

namic rules such as an external event, agreement, or

collaboration history.

We propose a role-based dynamic sharing control

model for our collaborative team based scenario. Our

system is owner centric and extends RBAC by using

various types of context and owner-deﬁned roles. We

present a hybrid role-based system using enterprise-

deﬁned roles E-Role and owner-deﬁned roles O-Role,

their life cycle including role assignment, usage, and

Kamran Malik A. and Dustdar S. (2010).

CONTEXT-AWARE SHARING CONTROL USING HYBRID ROLES IN INTER-ENTERPRISE COLLABORATION.

In Proceedings of the 5th International Conference on Software and Data Technologies, pages 42-48

DOI: 10.5220/0003013600420048

 SciTePress

revocation rules. We describe a role-based dynamic

sharing control model, its architecture, and imple-

mentation using Java based Web services environ-

ment. We evaluate our system using an example and

scenario related to sharing control in multiple over-

lapping teams and enterprises. A role-based dynamic

sharing control messenger is presented as a real world

application with a running example. These examples

show the importance of our scenario and model in real

world to preserve user privacy in complex collabora-

tive environments.

The remainder of this paper is organized as follows.

Section 2 describes background and related work.

section 3 shows motivating scenario and role-based

dynamic sharing control model. Section 4 explains

role-based dynamic sharing control. Section 5 de-

scribes role-based dynamic sharing control architec-

ture. Section 6 provides implementation and discus-

sion. Section 7 concludes the paper and introduces

future work.

2 BACKGROUND AND RELATED

WORK

In dynamic collaborative environments, context-

based sharing control and ﬁne-grained level of sharing

control are fundamental requirements. RBAC model

has been extended using context, for example, sys-

tem presented in (Covington et al., 2001) uses con-

text to dynamically change access rights. Context is

modeled as context roles in (Park et al., 2006). Our

system DySCon (Malik et al., 2009) extends RBAC

using context of requester, owner, and environment

and presents context-based dynamic sharing control

model. It tries to provide sharing control for owner

context where owner-deﬁned policy rules override

role-based policy of enterprise. In this paper, we ex-

tend DySCon to provide owner-deﬁned roles to re-

questers. Owner-deﬁned roles can be revoked using

predeﬁned context conditions. In (Groba et al., 2007),

owner sends one or more owner-deﬁned roles to re-

quester who can select one of them according to her

requirements. Difﬁculties with this system are role

selection, role creation without knowing the capabili-

ties of user in enterprise. Our system uses two types

of roles; conventional enterprise-based roles called E-

Role, and owner-deﬁned roles called O-Role. We de-

ﬁne link between two types of roles which is used for

selecting owner-deﬁned role for a user based on her

enterprise-deﬁned role. We also describe role usage

and revocation strategies which help in preserving pri-

vacy of owner’s context information.

Role-Based Access Control (RBAC) model

(Sandhu et al., 1996) has been widely used in collab-

orative systems due to its scalable nature and ease of

maintenance (Tolone et al., 2005). It reduces cost and

complexity of access control administration. Access

control systems (Shen and Dewan, 1992), (Ahn et al.,

2003), and (Thomas, 1997) describe different access

control models for collaborative environments with

different roles of users and their collaborative rights.

It is difﬁcult for RBAC to provide ﬁne-grained level

of access control because it is based on role (group

of users) and not on individual user. In addition,

RBAC alone can not handle dynamic environments

whose changes can be easily captured by making use

of context information. Some of the current systems

(Shen and Hong, 2005), (Kapsalis et al., 2006), and

(Coetzee and Eloff, 2007) make use of Web services

to share context information. A survey on context-

aware Web service systems can be found in (Truong

and Dustdar, 2009). Our system makes use of Web

services and context information in addition to owner-

deﬁned roles. We use a p2p based system to handle

dynamic nature of teams and relations between peers.

3 MOTIVATION

In this section we describe our role-based dynamic

sharing control scenario and present role-based dy-

namic sharing control model.

3.1 Role-based Dynamic Sharing

Control Scenario

Role-based dynamic sharing control scenario is

shown in Figure 1. Enterprises E1 and E2 collaborate

and create two software development teams T1 and

T2. Users from enterprises participate in both teams.

Some users can be member of both teams at a time,

for example, user U2. Enterprise-deﬁned roles are al-

ready assigned to users, for example, users with de-

veloper role are assigned E-Developer role, and team

leaders are assigned E-Leader role. A collaborative

activity A is created by both teams, users U1 and U2

are performing this activity. We describe a scenario

where user U1 is requested by other three users for

some services. Each of the three requesters is hav-

ing different activity and team relationship with user

U1. For example, user U2 is involved in the same ac-

tivity with user U1. User U1 feels no hesitation in

assigning her personal context to user U2 whom she

already knows and is collaborating with her. As per-

sonal context can only be assigned by owner-deﬁned

roles, so user U1 assigns role O-Developer to user U2

CONTEXT-AWARE SHARING CONTROL USING HYBRID ROLES IN INTER-ENTERPRISE COLLABORATION

Sharing request

Response (O-Role assignment or denial)

Team T1

Team T2

Enterprise E2Enterprise E1

Activity A

Developer

O-Colleague

E-Developer

Sharing Denied

E-Leader

E-Developer

Figure 1: Role-based Dynamic Sharing Control Scenario.

because she is already having E-Developer role by en-

terprise. A revocation rule based on their mutual ac-

tivity is set automatically by the system which revokes

O-Developer role from user U2 as soon as activity A is

ﬁnished. User U3, for example, is a trusted colleague

of user U1 in team T1 so she gets O-Colleague role

and can share personal context of user U1 to a level of

detail deﬁned for colleagues by user U1 in her sharing

rules for O-Colleague role. For colleagues, revoca-

tion rule can be set by owner of context U1 herself,

otherwise an event can revoke it, for example, any

change in role, team, enterprise, collaboration history

of any one of the requester or owner. User U4 hav-

ing a powerful role as leader of team T2 is not able

to access personal service of user U1 because user

U1’s system does not recognize her as a colleague,

friend etc. Her request is logged into the system and

if user U1 herself wants to assign her some role, she

can manually assign it.

3.2 Role-based Dynamic Sharing

Control Model

Our role-based dynamic sharing control system is

based on a dynamic collaborative environment where

number of entities are involved, for example, enter-

prise, team, activity, role, user, and services. These

entities described in our scenario are modeled with

their interactions, collaborations, and relationships as

shown in Figure 2. We explain each these entities be-

low.

Enterprise. Enterprise is the largest entity that cre-

ates team, assigns users to teams, and creates roles

for users. Enterprise monitors teams and their activ-

ities. Two or more enterprises collaborate and create

dynamic collaborative environment.

Team. One or more enterprises can create a team and

manage it for a joint project. A team is headed by

a team leader. A user can be part of more than one

teams at a time.

Activity. Activities can be created by enterprise or

team. Team leader selects appropriate users for per-

forming activities and monitors their progress. A

team can be considered as collection of sub-teams

based on groups of users performing activities.

Role. Roles encapsulates rights that are assigned to

users based on their job, qualiﬁcation, and experience.

One or more users can have same role and many roles

can be assigned to one user.

User. A user works for an enterprise in different

teams and activities having one or more roles. User

can share her context with other collaborating users

and deﬁnes her own sharing control rules.

Service. Services in our system are a way to share

context and information among users. Personal ser-

vices are used to share private information of user and

shared services are used for sharing activity and team

information.

4 ROLE-BASED DYNAMIC

SHARING CONTROL

In this section, we describe our hybrid role manage-

ment scheme and life cycle of an owner-deﬁned role

including role assignment and revocation scenarios.

Types of roles and evaluation of context sharing re-

quest are also described in this section.

4.1 Hybrid Role Management

Two types of roles are used in this system for privacy

of owner context and desired level of sharing control.

4.1.1 Enterprise-deﬁned Roles

Enterprises deﬁne sharing policies for their employ-

ees using enterprise-deﬁned roles E-Role which con-

tain rules for sharing control. These rules describe

who can share certain services under which condi-

tions. These roles are based on RBAC model. We

enhance these roles using context constraints which

ICSOFT 2010 - 5th International Conference on Software and Data Technologies

User

User-id Role

Profile Services

Role

Role-id Type

Permission Constraints

Interaction

Type Response

Time

Activity

Activity-id Services

Start date Team

End date Enterprise

Service

Service-id Owner

Type Context

Enterprise

Ent-id Departments

Goals Collaborations

Team

Team-id Users

Resources Location

Collaboration

Type Response

Duration Context

Collaboration

Type Result

Duration Context

Interaction

Type Response

Time

* ****

* *

performs

createscreates assigned tobelongs to

works for

assigned to

Figure 2: Simpliﬁed data model of entities and collaborations.

can also be used for dynamic activation and deactiva-

tion of roles.

4.1.2 Owner-deﬁned Roles

Owner-deﬁned roles O-Role are used for sharing per-

sonal context of owner. These roles are assigned when

enterprise-deﬁned role is not able to share context.

Assignment of these roles depends on collaboration

of owner and requester. There are two types of owner-

deﬁned roles which are described below.

A. Owner-deﬁned Enterprise-based Roles

These roles are linked with enterprise-deﬁned roles.

If users are participating in a mutual activity, team,

or enterprise, system can detect relationships and

provide roles related to requester’s enterprise-based

roles, for example, user having E-Developer role will

get O-Developer role. It provides advantage of per-

sonal context sharing at different levels, for example,

users having more powerful roles in enterprise will

get detailed personal context.

B. Owner-deﬁned Personal Roles

Detailed level of personal context sharing is only

available to users like personal friends or family of

the owner. Some colleagues from enterprise can also

be assigned these roles whom the owner trusts or are

her friends. Examples of these roles are O-Friend, O-

Colleague, O-Family etc.

4.2 Dynamic Revocation of Owner

Roles

Owner-deﬁned roles are provided to friends or few

collaborating users to access personal context. These

roles must be revoked as soon as they have been

used for the said purpose or deﬁned time limit. Their

excessive and uncontrolled use can be a threat for

user’s privacy. Role revocation can be based on static

information or dynamic events. Role revocation types

are described below.

Role Revocation Scenarios

Following types of static and dynamic rules are used

for role revocation.

• Time dependent revocation

Revoke owner role after a ﬁxed duration of time.

• Event-based revocation

Revoke role based on some event, for example,

activity ﬁnished or a change in any one of the

user’s enterprise, team, activity, or role.

• Context-based revocation

Revoke role when user context changes, for ex-

ample, location, online status etc.

• Agreement-based revocation

Revoke role after some agreement ﬁnish or vio-

lated. Example of agreement is ”i will share my

context if you share same context with me”.

• History-based revocation

Revoke role after tracking history, for example, no

email received from user in last 3 days.

4.3 Handling Context Sharing Request

A high level view of context sharing request using

enterprise-deﬁned roles E-Role and its response based

on owner-deﬁne roles O-Role including major com-

ponents of our system is shown in Figure 3.

It describes that E-Role based request is sent to

sharing controller component of owner system which

CONTEXT-AWARE SHARING CONTROL USING HYBRID ROLES IN INTER-ENTERPRISE COLLABORATION

Owner

O-Role granted

Role

Manager

Privacy

Controller

(Revocation

Rules and

Sharing Levels)

Requester

E-Role based

Context request

Sharing

Controller

Context

Manager

Figure 3: Request for sharing context.

uses other components for request handling. Privacy

controller, Context manager, and role manager are

used to evaluate request based on sharing rules, cur-

rent context, and collaboration. To grant a personal

context of owner, owner-deﬁned roles O-Role are re-

quired. Privacy controller controls the grant of O-

Role by deﬁning role revocation rules, and controls

context sharing up to certain level of granularity de-

pending on role and context of requester.

5 ROLE-BASED DYNAMIC

SHARING CONTROL

ARCHITECTURE

Our role-based dynamic sharing control architecture

is shown in Figure 4. It is a Web service based peer

to peer system where context is shared using Web ser-

vices. Our architecture consists of sharing controller,

privacy controller, context provider, and role man-

ager. Other components include sharing rules, col-

laboration and contact history, assigned roles, and

revocation rules. Interaction and working of these

components is described below.

Sharing

Rules

Assigned

Roles

Revocation

Rules

Collab&Con

tact History

Read data Read & store data

Store data

Context

Manager

Sharing Controller

Privacy Controller

Role

Manager

Owner Peer

Requesting Peer

RequestReply

Service call

Figure 4: Role-based Dynamic Sharing Control Architec-

ture.

5.1 Sharing Controller

Sharing controller accepts requests from users and

provide requested context and roles to user. It uses

sharing rules to check for validity of user request,

for example, requester’s role and current context con-

ditions. Sharing control rules are deﬁned by enter-

prise based on enterprise roles. Context manager pro-

vides requested context for validating context condi-

tions and for granting requested context. If request

is not valid according to sharing control rules, col-

laboration and contact history database is accessed

through privacy controller to ﬁnd any collaboration

of requester with owner.

5.2 Privacy Controller

Privacy controller uses collaboration and contact his-

tory database to ﬁnd requester’s collaboration with

owner of context. A collaborator is allowed to get

owner-deﬁned role O-Role to access owner’s personal

context information. Role manager is used for assign-

ing owner-deﬁned roles O-Role to requesting users. It

also uses static and dynamic revocation rules to re-

voke a role from user. It can also contact with context

manager for the user’s current context required by re-

vocation rules.

5.3 Context Provider

Context provider provides requested context to re-

quest handling components. It arranges context in-

formation in hierarchical levels, so that only required

level of context is shared with a requester. Our

system uses context of various types including re-

quester, owner, and all other entities involved in the

system. Context is used for context sharing in our

system. This means that we use context at two lev-

els, ﬁrstly for sharing personal and shared context of

users, and secondly for validating sharing rules, re-

vocation rules, and level of sharing based on context

conditions.

5.4 Role Manager

Role manager assigns owner-deﬁned roles to request-

ing users when decided by the privacy controller. It

provides two types of roles; roles which are deﬁned

based on enterprise roles E-Role, and roles that are not

based on enterprise roles and are used for sharing with

friends, family, or trusted colleagues in enterprise.

ICSOFT 2010 - 5th International Conference on Software and Data Technologies

6 IMPLEMENTATION AND

DISCUSSION

Role-based dynamic sharing control system is imple-

mented using Java Web services and is designed as

a peer to peer system. Each user, team, and enter-

prise is a peer. Collaborating users can request con-

text services from other users using Web service calls.

We describe the importance of our work in real world

scenario presented in Section 3.1 using role-based dy-

namic sharing control messenger shown in Figure 5.

Figure 5: Role-based Dynamic Sharing Control Messenger.

As described in our scenario in Section 3.1, users

U1, U2, U3 and U4 are collaborating in overlapping

teams T1 and T2, created by enterprises E1 and E2.

Figure 5 describes one of the user peers owned by

user U2. The user U2 can watch her online collab-

orators who are user U1 and U3. Personal services

of each user U1 and U3 are available under their

names which can be accessed by U2. As user U1 and

U2 are performing same activity A which is actually

the software design activity for developers having E-

Developer role. When user U2 requests user U1 by

selecting her activity service, the sharing controller

of user U1 ﬁnds that having role E-Developer user U2

is not allowed the activity service. It hands over re-

quest to privacy controller which validates user U2 as

a collaborator in a recent ongoing design activity and

so ﬁnds her a candidate for assigning an owner-based

role O-Developer. It also sets revocation rules for this

role to user U2 assignment and sets level of sharing

for this role under given context conditions. In this

case revocation rule is based on design activity dura-

tion. Finally, user U2 is assigned role O-Developer

and also gets reply from sharing controller of U1’s

peer containing the requested activity context at cer-

tain level of detail allowed to this role as shown in

Figure 5. Similarly other users U3 and U4 can share

context from user U1 using her provided services. Ac-

cording to our scenario in Section 3.1, user U3 gets

O-Colleague role being recognized just as a colleague

of user U1, so she gets the context being shared at a

higher level of granularity. The user U4 gets a shar-

ing denied message having no collaboration with user

U1.

Sharing control scenario and application de-

scribed above show the importance of privacy of

owner context being shared in complex real world

scenarios involving multiple entities and their collab-

orations. Our system allows sharing of context based

on owner-deﬁned roles and context conditions up to

a certain level of granularity and for certain time to

preserve the privacy of owner context.

7 CONCLUSIONS

Context-based and hybrid role techniques are used to

provide sharing control and privacy to owner’s con-

text information. RBAC is extended to include con-

text constraints and owner-deﬁned roles. Role revoca-

tion for O-Roles is provided based on different types

of rules like static rules, for example, ﬁxed time limit,

or dynamic rules, for example, event-based rules. A

Web services based architecture of the system is pro-

vided which describes working of all components to

provide required level of sharing control. Future work

includes the use of autonomic techniques for auto-

matic assignment and revocation of owner-deﬁned

roles.

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