1. A method, including: receiving a description of a desired result for a document to be assembled including content from a source document, wherein the description is associated with a metalanguage or a natural language, wherein the description specifies the content from the source document to be included the document to be assembled, and wherein the description at least in part specifies a layout of the content of the desired result; determining an optimized set of operations using a processor such that executing the optimized set of operations would produce the desired result, wherein the optimized set of operations is determined to provide an optimized sequence of operations, including: building a representation of the description of the desired result, wherein the representation provides a blueprint of the desired result; building the blueprint for assembling the document to be assembled, wherein the blueprint specifies operations that enable application of shared properties on sub-assemblies, and wherein each segment is associated with one of the plurality of source documents and a context; and associating each object in the representation with a segment of the desired result; and providing the optimized set of operations as input to a plurality of applications to generate an assembled document including content from the source document; wherein a plurality of applications are used to execute the set of operations, wherein the set of operations includes a first operation and a second operation, wherein a first operation that is associated with the first application is input to the first application for executing the first operation, and wherein the second operation that is associated with a second application is input to the second application for executing the second operation; and wherein the desired result includes a composite document based on the description and the content from a plurality of source documents, wherein the content from a plurality of source documents includes content based on user selected source icons representing the plurality of source documents, and wherein a user selected order of the user selected source icons is used to determine an order of the source documents represented in the desired result.