1. A computer comprising: one or more central processing units, one or more memories and one or more network interfaces to one or more networks, the computer further comprising a program code which, when executed on said one or more central processing units, is configured to perform a search and a business transaction based on user input, a user interface comprising at least one display being configured to display in conjunction with execution of the program code, an input environment configured for user inputting of search criteria, said input environment being configured for user inputting of an order, said search criteria defining a search for at least one desired entity; the program code establishing a search engine configured for performing a search on at least two different web-based data sources to generate a search result; the search engine being configured to search based on the user input of a configuration comprising a combination of at least two different entities, a first entity and a second entity being includable in the at least two different entities that the search engine is configured to search, the search engine establishing a search for the configuration, wherein the different entities are purchasable from different web-based data sources, said search engine being configured for performing a search for said configuration on at least two different web-based data sources for said combination of entities, said search engine presenting at least one found configuration of the different entities by means of said user interface, said search engine being configured to provide at least one order input defining a configuration determined on the basis of said at least one found configuration presented by means of said user interface, said search engine being configured to take mutual dependencies between said entities into consideration.