Once you have created your function context and function classes, and tested the classes that do the actual custom function work, you can create a contribution. All the function contexts in the project are automatically packaged when you create a deployment contribution.
The custom functions are available only to the BPEL files in the contribution or in a contribution in another project that references this project. Note that the custom functions are listed on the Catalog Resources page of the Export Business Process Archive, either as project resource dependencies, referenced dependencies, or if they are not referenced, they are listed as additional resources. For details, see
Deploying Project Dependencies and Viewing Excluded Dependencies.