Visual composition of workflows enables end user to visually depict the workflow as a graph of activities in a process. Tools that support visual composition translate those visual models to traditional workflow languages such as BPEL and execute them thus freeing the end user of the need of knowing workflow languages. Mashups on the other hand, provide a lightweight mechanism for ordinary user centric service composition and creation, hence considered to have an active role in the web 2.0 paradigm. In this paper, we extend a visual workflow composition tool to support mashups, thus providing a comprehensive tooling platform for mashup development backed up by workflow style modeling capabilities, while expanding the reach of the workflow domain into web 2.0 resources with the potential of the mashups. Furthermore, our work opens up a new possibility of converging the mashup domain and workflow domain, thus capturing beneficial aspects from each domain.
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Before going into the Mooshabaya research, it is worth to have a look at the roots of Mooshabaya. JavaScript based Mashups - A content aggregation technology, that is used to compose services by remixing two or more sources [sample mashup site]. And the workflows - We prefer to represent real world processes as a sequence of operations, and here comes workflows. In practice both the mashups and the workflows have their own domain of applications. Workflows have gained their major use cases from the research communities as scientific workflows and the business communities as the business workflows. Mashups mostly target the end users and empower the user-oriented web.
What if a merge of the domains is possible? Can the domains use each other? This became the core research of Mooshabaya.
Mooshabaya composes workflows graphically, and exports them as mashups. The mashups can then be executed and monitored at run time.
What motivates us into Mooshabaya? We have two major views. 1) As a Mashup Composer - Mashups can be created graphically by dragging and dropping components. 2) Extending the reach of the workflow domain. This includes web based APIs and web contents such as feeds. Mashup also becomes an alternative lightweight medium for workflow execution.
Before going further into Mooshabaya, we look at the related works. Yahoo Pipes, JackBe Presto, and Serena are some of the Mashup composers, that allow visual mashup composition through their graphical user interface. XBaya, Taverna, Triana, CAT (Composition Analysis Tool), Kepler, and Pegasus are some of the graphical workflow composers. Each of these tools has its own set of features and target use cases.
So what is special about Mooshabaya? Visual Mashup Composers mostly restrict themselves to Web 2.0 APIs. So far mashups are seen mostly as a content aggregation technology. Existing mashup composers do not support the monitoring of the execution of the mashups at run time. When considering the workflow composers, the traditional workflow languages have a high learning curves. Content aggregation is minimally supported in the existing tools. Mooshabaya is expected to fill these gaps in both the domains.
Let's have a look at the implementation of Mooshabaya. Registry Integration, Mashup Generation, Deployment, Monitoring, Security and the user interface are the major components.
Here we have the major use case of Mooshabaya.
First the user wants to compose workflows - He integrates a web service registry into the system. Then he discovers and fetches the services metadata from the registry. By dragging and dropping the metadata files and other service components into the Mooshabaya canvas, he composes the workflows.
Then he exports the workflow as a mashup. After that he can deploy the mashups into a mashup server. Here mashups are deployed into a mashup server and the relevant workflow files and the service metadata are stored into a registry. After the deployment, he can execute the mashups deployed in the mashup server and monitor them at the execution time. Secured services found in an Identity Server too can be used in the workflow composition.
As we discussed, Mooshabaya provides a solution for the complete mashup life cycle, where the existing products are not providing at the moment. For example the monitoring phase of the mashups.
Our reasearch was mostly focused on the two domains. The integration of a WS-Eventing based notification system for remote monitoring of the mashups. Next we have the mashup security, based on username password based authentication.
Mooshabaya has used XBaya as the core workflow composer. Rather we can consider it a mashup generator for XBaya. WSO2 Mashup Server is used as the mashup server for Mooshabaya, and WSO2 Governance Registry as the web services registry. For the performance analysis, we benchmarked its performance against the XBaya's existing options. The performance graphs compare the file sizes and the generation times. The mashup file size was considerably smaller than the respective BPEL file, thus reducing the time to deploy the file to a remote server. The mashup generation time and BPEL generation time too were close to each other, without much difference.
Scientific researches such as the LEAD system, business processes, and educational researches are the major target users of Mooshabaya. As a point for future works, we can mention that, Mooshabaya still can be extended with further research, specifically a web based interface, and the support for the delegated authentication scenarios.
