The APIB gateway currently supports browsing and querying of IRs and partial browsing of APs. It contains only a subset of the initial release of STEP. There is a need both to expand the collection of documents accessible through the APIB gateway and to provide a wider variety of services to users. The IRs and APs currently available were converted into SGML manually from documents originally written using commercial word processing software. Although conversion of legacy data into SGML is a long and tedious process, efforts are underway to tag the remaining existing STEP IRs using the NIST-developed DTD. Tagging the rest of the IRs in the initial release of ISO 10303 is the highest priority. The next highest priorities are tagging IRs that have attained Draft International Standard (DIS) status and tagging the remaining APs in the initial release. In the mean time, current AP developers are being encouraged to use a NIST-supplied environment[PHIL] for authoring new STEP AP and IR documents in SGML. In the near future, the APIB gateway's functionality will be extended to allow users to access all components of SGML-tagged STEP IRs and APs. This will require extending the APIB's data access services to support information retrieval from AP documents using the full set of structures defined in the AP DTD.
Plans also call for expanding the scope of the APIB and the APIB gateway to include documents created during AP development that are separate from the STEP AP document. Examples of these documents are issue logs, status summaries, and validation reports. Error reports and enhancement requests resulting from implementation experience may be included as well. These documents may not be represented in SGML but nevertheless will need to be associated with elements in the SGML-tagged APs and IRs in the APIB. Thus the APIB gateway will have to support hypertext browsing between SGML and non-SGML documents. More sophisticated linking mechanisms such as those specified in the TEI Guidelines (Section 5.2) or in HyTime (Section 5.3) may be desirable for this purpose.
In addition, efforts are underway to provide users with access through the APIB gateway to tools for creating EXPRESS models. This will be done by providing a World Wide Web interface to the NIST EXPRESS Server[LIBES94], a service that allows users to run EXPRESS software tools remotely without installing them locally. The EXPRESS Server currently uses electronic mail for its user interface. Users send requests and EXPRESS code to the Server as e-mail. The output from running an EXPRESS tool can then be e-mailed back to the user, or it can be stored in the user's private directory on the Server. Once the EXPRESS Server is made accessible through the APIB gateway, STEP AP developers will be able to build EXPRESS models re-using IR constructs by querying the APIB for the desired constructs and feeding the results directly into an EXPRESS tool. Among the tools available through the EXPRESS Server are an EXPRESS syntax checker as well as a tool for converting an EXPRESS schema with external references (see Figure 4) into a self-contained EXPRESS model[LIBES93]. This latter tool is very useful for building the ``system integrator's view information model'' discussed in Section 3.2 because this EXPRESS model needs to be self-contained so that an AP implementor can use it as a specification without having to refer to additional documents in ISO 10303.