Dominik Seiler

A scalable service-oriented architecture for multimedia analysis, synthesis and consumption

Although Service-Oriented Architectures (SOAs) were not designed for multimedia processing, they speed up the development of distributed multimedia applications by allowing the composition or reconfiguration of existing services. For example, the Business Process Execution Language for Web Services (BPEL) is a powerful tool to orchestrate, model and execute workflows. However, due to its process-oriented approach, it is not directly applicable to data-intensive applications, such as those from the multimedia domain. In this paper, a comprehensive service-oriented infrastructure for multimedia applications is presented that (a) overcomes some drawbacks of BPEL for data-intensive applications and (b) provides tools that further ease the development and use of web services for a broad scope of multimedia applications covering video content analysis, audio analysis and synthesis and multimedia consumption. The proposed service-oriented infrastructure can be easily integrated into existing business processes by using BPEL. A dynamic allocation of cloud computing resources ensures the scalability of a multimedia application. To allow efficient and flexible data transfers in BPEL workflows, an implementation of the Flexible SOAP with Attachments (Flex-SwA) architecture is used that allows data transmission in conjunction with SOAP messages. The protocol requirements of services in the case of real-time, streaming or file transfer can be described by a communication policy. Three use cases of multimedia applications are evaluated.

Data Flow Driven Scheduling of BPEL Workflows Using Cloud Resources

In this paper, an approach to assign BPEL workflow steps to available resources is presented. The approach takes data dependencies between workflow steps and the utilization of resources at runtime into account. The developed scheduling algorithm simulates whether the makespan of workflows could be reduced by providing additional resources from a Cloud infrastructure. If yes, Cloud resources are automatically set up and used to increase throughput. The proposed approach does not require any changes to the BPEL standard. An implementation based on the ActiveBPEL engine and Amazons Elastic Compute Cloud is presented. Experimental results for a real-life workflow from a medical application indicate that workflow execution times can be reduced significantly.

Long-Term Incremental Web-Supervised Learning of Visual Concepts via Random Savannas

The idea of using image and video data available in the World-Wide Web (WWW) as training data for classifier construction has received some attention in the past few years. In this paper, we present a novel incremental and scalable web-supervised learning system that continuously learns appearance models for image categories with heterogeneous appearances and improves these models periodically. Simply specifying the name of the concept that has to be learned initializes the proposed system, and there is no further supervision afterwards. Textual and visual information on web sites are used to filter out irrelevant and misleading training images. To obtain a robust, flexible, and updatable way of learning, a novel learning framework is presented that relies on clustering in order to identify visual subclasses before using an ensemble of random forests, called random savanna, for subclass learning. Experimental results demonstrate that the proposed web-supervised learning approach outperforms a support vector machine (SVM), while at the same time being simply parallelizable in the training and testing phases.

Efficient data transmission in service workflows for distributed video content analysis

Workflows of web services orchestrated by the Business Process Execution Language (BPEL) have been successfully used in many business applications. Although these technologies were not originally designed for multimedia processing, they offer advantages to speed up the development of distributed multimedia analysis applications by allowing the composition or reconfiguration of existing services. However, in the case of service-oriented distributed video content analysis, a huge amount of binary data has to be transferred between different services. As a consequence, service orchestration based on BPEL leads to a performance bottleneck due to indirect message and data transport: the workflow engine receives results (which are potentially very large) from finished services and passes them to a subsequent service. In this paper, we present two novel approaches based on our previously developed Flex-SwA framework to model the binary data transmission between services in BPEL workflows. The proposed approaches circumvent the performance bottleneck at the orchestrating engine and provide efficient possibilities to transfer large data amounts as well as large data units. The first approach models the data flow in BPEL; the services exchange data directly. The second approach models the data flow outside of the BPEL engine and shifts it completely to the Flex-SwA framework. Experimental results for a video analysis workflow demonstrate the advantages of the proposed approaches.

MIRO: a mashup editor leveraging web, Grid and Cloud services

High performance computing resources are currently mainly used by computer scientists or domain experts. With the upcoming Cloud computing infrastructures and the vast amount of data available in the World Wide Web, such computing resources become interesting for end users who want to develop their own computationally demanding applications. In this paper, a service-enabled mashup editor called MIRO is presented to assist end users in the task of developing distributed applications utilizing high performance computing resources. MIRO allows the combination of popular web applications with Grid and Cloud services. The separation of the view into a user and developer view allows both the user and the developer to easily work with the editor. Two use cases are presented to show how Flickr and YouTube search can be combined with multimedia analysis services.

Exposing validity periods of prices for resource consumption to web service users via temporal policies

Web services usually have functional as well as non-functional properties. Functional properties, such as the WSDL description, are usually static, whereas non-functional properties are often dynamic and thus vary over time. One of these non-functional properties are prices for using a web service or the resources it consumes. It is desirable to dynamically set prices depending on criteria such as the time of day or usage patterns and to expose pricing information in several ways. In this paper, we introduce an extended version of our previously proposed temporal policy language to handle these requirements. The extension provides the possibility of adding the exposition of validity periods to service users by weaving an attribute from the temporal policy namespace to WS-Policies. Furthermore, a schema for temporal policies and a state diagram are introduced. A use case from the area of pricing high performance computing resources is presented to demonstrate that exposing validity periods to service users enables them to automatically estimate how long they can use computing resources for a given price.

LCDL: an extensible framework for wrapping legacy code

If legacy code has to be integrated into an application, it is often necessary to call this code available as source code written in a particular programming language or available in binary format for a particular computing platform from another programming language or from a remote machine. For this reason, wrapping code has to be developed for each source code library or binary code to be integrated. This paper presents an extensible framework that supports legacy code integration by modeling legacy code not only in a way that is programming (language) independent, but also by supporting different input and output types and bindings. This aim is achieved by the use of an integrated plug-in mechanism.

SimpleBPEL: Simplified Modeling of BPEL Workflows for Scientific End Users

The Business Process Execution Language (BPEL) is a reasonable choice for modeling workflows in a web service environment, but it has a high acceptance threshold for users with no workflow skills. To improve the usability of BPEL for non-tech savvy scientific end users, we present SimpleBPEL, a modeling tool for composing workflows of SimpleBPEL fragments that encapsulate BPEL logic. The implementation is based on Eclipse and automatically generates standard-compliant BPEL workflows. A usage example from the area of media research shows the usefulness of the presented approach.

The Web Service Browser: Automatic Client Generation and Efficient Data Transfer for Web Services

Web services are supported by almost all major software vendors, but nevertheless there is still a certain barrier that prevents a broader user community to actually use them. The barrier is the lack of appropriate clients offered in conjunction with the services. This paper presents a Web Service Browser that automatically generates a dynamic user interface when the user browses to the location of the service description and additionally handles the invocation of the service. To ease the use of the service, the browser takes care of data management by using an implementation of the Flex-SwA architecture. Results are presented to the user in a human-readable manner. When the result contains multimedia data, an audio or video player is used to present the result. Use cases demonstrate the benefits of the browser. With the Web Service Browser, web services simply become a usable component offered in the WWW.

Efficient data transmission between multimedia web services via aspect-oriented programming

The number of web services capable of processing multimedia data is growing. Typically, a multimedia web service realizes only a specific algorithmic processing step, such as video decoding. Thus, it is desirable to compose several web services hosted on different sites into a new value-added workflow. However, the transfer of large amounts of multimedia data within workflows based on SOAP as the prevalent communication paradigm between web services induces redundant data transfers. In previous work, we have presented a reference technique called Flex-SwA that solves this problem. However, its usage is accompanied by additional software development efforts that have to be repeated when a new service or client is implemented. In this paper, we present an aspect-oriented programming approach that significantly reduces these software development efforts. The solution allows developers to easily extend existing multimedia web services with the capability of efficient data transmission without modifying the implementations of the original services, while at the same time the advantages of SOAP web services are still maintained. Experimental results for a distributed video analysis workflow demonstrate the feasibility of the presented approach.