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Papers by Debmalya Biswas

Data & Knowledge Engineering, 2009

Peer to Peer (P2P) communities (or “interest groups”) are referred to as nodes that share a commo... more Peer to Peer (P2P) communities (or “interest groups”) are referred to as nodes that share a common interest. Each peer in the system claims to have some interests and, accordingly, would like to become a member of these groups. The available interest groups are arranged according to a hierarchical semantics ontology, and managed with a semantic overlay network. P2P community structure is highly dynamic: a peer may be added to or deleted from a community; communities may be added or deleted; communities may be merged or split; and sub-communities may become parent-level communities and vice versa. In this paper, we propose a highly flexible multi-level data structure to capture the visibility aspect of P2P communities. The data structure is simple, facilitates dynamic changes easily and efficiently in a decentralized fashion, and is highly scalable.

Industry and researchers acknowledge Web services as being the next generation of distributed com... more Industry and researchers acknowledge Web services as being the next generation of distributed computing. However, several issues especially the reliability aspect needs to be addressed before Web services can deliver its promise. Due to their heterogeneous, autonomous and long-lived nature, traditional ACID (Atomicity, Consistency, Integrity, Durability) based models are not sufficient for providing transactional guarantee to Web services compositions. To overcome this limitation, many extended transaction models have been proposed based on the concept of compensation. In this paper, we stress on the importance of two aspects, the Cost of Compensation and End User Involvement, which are missing from most of the transaction models proposed until now. We also show how industry standards like BPEL4WS, WS-Transaction can be augmented to facilitate the above aspects. Finally, we propose a simple classification towards describing compensating operations.

The most promising feature of the Web services platform is its ability to form new services by co... more The most promising feature of the Web services platform is its ability to form new services by combining the capabilities of existing services, i.e., its compos ability. The existing services may themselves be composed of other services, leading to a hierarchical composition. In a hierarchical composition, providers vary in the visibility they have over the other providers in the composition. For example, a provider may not be aware of any providers in the hierarchy other than its parent and children. On the other hand, a provider may be aware of all other providers in the hierarchy. Towards this end, we introduce the notion of spheres of visibility (SoV) as an abstraction to capture the upward/downward visibility aspects of the providers in a hierarchical composition. The latter part of this paper deals with compensation. We outline a compensation mechanism for hierarchical compositions conforming to the visibility restrictions modeled as SoV.

We consider hierarchical systems where nodes represent entities and edges represent binary relati... more We consider hierarchical systems where nodes represent entities and edges represent binary relationships among them. An example is a hierarchical composition of Web services where the nodes denote services and edges represent the parent-child relationship of a service invoking another service. A fundamental issue to address in such systems is, for two nodes X and Y in the hierarchy whether X can see Y, that is, whether X has visibility over Y. In a general setting, X seeing Y may depend on (i) X wishing to see Y, (ii) Y wishing to be seen by X, and (iii) other nodes not objecting to X seeing Y. The visibility could be with respect to certain attributes like operational details, execution logs, security related issues, etc. In this paper, we develop a generic conceptual model to express visibility. We study two complementary notions: sphere of visibility of a node X that includes all the nodes in the hierarchy that X sees; and sphere of noticeability of X that includes all the nodes that see X. We also identify the dual properties, coherence and correlation, that relate the visibility and noticeability notions. We propose elegant methods of constructing the spheres with these properties.

The most promising feature of the Web services platform is its ability to form new services by co... more The most promising feature of the Web services platform is its ability to form new services by combining the capabilities of already existing services, i.e., its composability. The existing services may themselves be composed of other services, leading to a hierarchical composition. In this work, we focus on the monitoring aspect for hierarchical Web services compositions. We are primarily interested in capturing the state of a hierarchical composition at any given point of time (snapshot). We discuss in detail how some of the snapshot algorithms proposed in literature can be extended in a Web services context. Snapshots usually reflect a state of the system which “might have occurred”. Towards this end, we show how we can acquire a state that “actually occurred” from such snapshots. Finally, we discuss the different types of execution related queries and how we can answer them using the captured snapshots.

With more and more data stored into XML databases, there is a need to provide the same level of f... more With more and more data stored into XML databases, there is a need to provide the same level of failure resilience and robustness that users have come to expect from relational database systems. In this work, we discuss strategies to provide the transactional aspect of atomicity to XML databases. The main contribution of this paper is to propose a novel approach for performing updates-in-place on XML databases, with the undo statements stored in the same high level language as the update statements. Finally, we give experimental results to study the performance/storage trade-off of the updates-in-place strategy (based on our undo proposal) against the deferred updates strategy to providing atomicity.

... Debmalya Biswas Nokia Research Center, Lausanne, Switzerland debmalya.biswas@ nokia.com ... M... more ... Debmalya Biswas Nokia Research Center, Lausanne, Switzerland debmalya.biswas@ nokia.com ... Many apps (including some of the most popular ones) have been observed to misuse the install-time access given to them at run-time. ...

Data & Knowledge Engineering, 2009

Peer to Peer (P2P) communities (or “interest groups”) are referred to as nodes that share a commo... more Peer to Peer (P2P) communities (or “interest groups”) are referred to as nodes that share a common interest. Each peer in the system claims to have some interests and, accordingly, would like to become a member of these groups. The available interest groups are arranged according to a hierarchical semantics ontology, and managed with a semantic overlay network. P2P community structure is highly dynamic: a peer may be added to or deleted from a community; communities may be added or deleted; communities may be merged or split; and sub-communities may become parent-level communities and vice versa. In this paper, we propose a highly flexible multi-level data structure to capture the visibility aspect of P2P communities. The data structure is simple, facilitates dynamic changes easily and efficiently in a decentralized fashion, and is highly scalable.

Industry and researchers acknowledge Web services as being the next generation of distributed com... more Industry and researchers acknowledge Web services as being the next generation of distributed computing. However, several issues especially the reliability aspect needs to be addressed before Web services can deliver its promise. Due to their heterogeneous, autonomous and long-lived nature, traditional ACID (Atomicity, Consistency, Integrity, Durability) based models are not sufficient for providing transactional guarantee to Web services compositions. To overcome this limitation, many extended transaction models have been proposed based on the concept of compensation. In this paper, we stress on the importance of two aspects, the Cost of Compensation and End User Involvement, which are missing from most of the transaction models proposed until now. We also show how industry standards like BPEL4WS, WS-Transaction can be augmented to facilitate the above aspects. Finally, we propose a simple classification towards describing compensating operations.

The most promising feature of the Web services platform is its ability to form new services by co... more The most promising feature of the Web services platform is its ability to form new services by combining the capabilities of existing services, i.e., its compos ability. The existing services may themselves be composed of other services, leading to a hierarchical composition. In a hierarchical composition, providers vary in the visibility they have over the other providers in the composition. For example, a provider may not be aware of any providers in the hierarchy other than its parent and children. On the other hand, a provider may be aware of all other providers in the hierarchy. Towards this end, we introduce the notion of spheres of visibility (SoV) as an abstraction to capture the upward/downward visibility aspects of the providers in a hierarchical composition. The latter part of this paper deals with compensation. We outline a compensation mechanism for hierarchical compositions conforming to the visibility restrictions modeled as SoV.

We consider hierarchical systems where nodes represent entities and edges represent binary relati... more We consider hierarchical systems where nodes represent entities and edges represent binary relationships among them. An example is a hierarchical composition of Web services where the nodes denote services and edges represent the parent-child relationship of a service invoking another service. A fundamental issue to address in such systems is, for two nodes X and Y in the hierarchy whether X can see Y, that is, whether X has visibility over Y. In a general setting, X seeing Y may depend on (i) X wishing to see Y, (ii) Y wishing to be seen by X, and (iii) other nodes not objecting to X seeing Y. The visibility could be with respect to certain attributes like operational details, execution logs, security related issues, etc. In this paper, we develop a generic conceptual model to express visibility. We study two complementary notions: sphere of visibility of a node X that includes all the nodes in the hierarchy that X sees; and sphere of noticeability of X that includes all the nodes that see X. We also identify the dual properties, coherence and correlation, that relate the visibility and noticeability notions. We propose elegant methods of constructing the spheres with these properties.

The most promising feature of the Web services platform is its ability to form new services by co... more The most promising feature of the Web services platform is its ability to form new services by combining the capabilities of already existing services, i.e., its composability. The existing services may themselves be composed of other services, leading to a hierarchical composition. In this work, we focus on the monitoring aspect for hierarchical Web services compositions. We are primarily interested in capturing the state of a hierarchical composition at any given point of time (snapshot). We discuss in detail how some of the snapshot algorithms proposed in literature can be extended in a Web services context. Snapshots usually reflect a state of the system which “might have occurred”. Towards this end, we show how we can acquire a state that “actually occurred” from such snapshots. Finally, we discuss the different types of execution related queries and how we can answer them using the captured snapshots.

With more and more data stored into XML databases, there is a need to provide the same level of f... more With more and more data stored into XML databases, there is a need to provide the same level of failure resilience and robustness that users have come to expect from relational database systems. In this work, we discuss strategies to provide the transactional aspect of atomicity to XML databases. The main contribution of this paper is to propose a novel approach for performing updates-in-place on XML databases, with the undo statements stored in the same high level language as the update statements. Finally, we give experimental results to study the performance/storage trade-off of the updates-in-place strategy (based on our undo proposal) against the deferred updates strategy to providing atomicity.

... Debmalya Biswas Nokia Research Center, Lausanne, Switzerland debmalya.biswas@ nokia.com ... M... more ... Debmalya Biswas Nokia Research Center, Lausanne, Switzerland debmalya.biswas@ nokia.com ... Many apps (including some of the most popular ones) have been observed to misuse the install-time access given to them at run-time. ...