1. A computer implemented relation information constructing method for constructing, by computer processing, relation information between a plurality of data elements structured in a first directed acyclic graph (DAG) in a first domain and a plurality of data elements structured in a second DAG in a second domain on the basis of a preassigned relation between data elements, the method comprising: accessing the plurality of data elements in the first directed acyclic graph (DAG) in the first domain and the plurality of elements in the second DAG in the second domain, wherein the first DAG and the second DAG; importing, using a processing device, data related to the first DAG from the first domain and data related to the second DAG from the second domain in order to generate a relation graph; identifying assignment of a relation between a node v a of the first DAG and a node v b of the second DAG; generating, in response to the relation between the node v a and the node v b , a join node to connect the first DAG to the second DAG, wherein the join node is positioned between the node v a and the node v b in the relation graph, and wherein the join node is a node linking a node positioned upstream of the node v a in the first DAG to a node positioned upstream of the node v b in the second DAG; and generating one or more additional join nodes, wherein the generating comprises, as long as there is a pair of node v a of the DAG of the first domain and node v b of the DAG of the second domain that do not have a join node, generating a join node v between v a and v b in the relation graph, and generating an edge (v a , v) and an edge (v b , v) in the relation graph; wherein, after generating the one or more additional join nodes, the first DAG is independently manageable by a first tool configured for the first domain, the second DAG is independently manageable by a second tool configured for the second domain and distinct from the first tool, and a third domain comprising the one or more additional join nodes is manageable by a centralized tool.