Digital Signal Processing (DSP) applications are often designed with tools based on dataflow graphs and the increasing number of such tools shows the need for a common intermediate graph representation for exchanging dataflow information. In this work, we present the dataflow interchange format (DIF), a platform-independent textual language that is geared towards capturing the semantics of graphical design tools for DSP system design. A key objective of DIF is to facilitate technology transfer across dataflow-based DSP design tools by providing a common, extensible semantics for representing coarse-grain dataflow graphs, and recognizing useful subclasses of dataflow models. This thesis also develops the framework for a Java-based software repository that provides dataflow analysis and optimization algorithms for DIF representations. The featured framework is accompanied by toolboxes for hierarchical design support and visualization of graphs.