We describe an approach to create a synthetic workload for large scale extensional query answering experiments. The workload comprises multiple interrelated domain ontologies, data sources which commit to these ontologies, synthetic queries and map ontologies that specify a graph over the domain ontologies. Some of the important parameters of the system are the average number of classes and properties of the source ontology which are mapped with the terms of target ontology and the number of data sources per ontology. The ontology graph is described by various parameters like its diameter, number of ontologies and average out-degree of node ontology. These parameters give a significant degree of control over the graph topology. This graph of ontologies is the central component of our synthetic workload that effectively represents a web of data.