SEDRIS Transmittal Format (STF)

The STF may be downloaded as part of the SEDRIS SDK Release from the SEDRIS SDK Product Downloads page.

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The abstract SEDRIS transmittal format (STF) provides a platform independent interchange mechanism for SEDRIS transmittals. The STF is a conceptual file format that defines the organization of a persistent SEDRIS transmittal. In SEDRIS, a SEDRIS producer application uses the SEDRIS API to map an internal native database format to the SEDRIS Data Representation Model (DRM). That portion of the SEDRIS API that accesses a SEDRIS transmittal is called the SEDRIS Transmittal API. A SEDRIS application that uses the SEDRIS Transmittal API can do a runtime conversion from the producer native database format to the SEDRIS DRM. This process is termed “in-memory conversion”. This data is then available for SEDRIS-based consumer applications, such as the Model Viewer, or conversion software to other native formats.

In-Memory Conversion

Unfortunately, there is a problem with this method of data exchange. The problem is that such SEDRIS API implementations are platform and format dependent. Thus, when an attempt is made to consume data from a different native database, a new conversion software module is required. This new module must also be compatible with the old module, because both are accessed by the SEDRIS API. Since a purpose of SEDRIS is to provide an interchange mechanism among all vendors and eliminate as much extraneous software as possible, a single mechanism that is platform independent is required, thus the STF.

What is the STF?

The STF represents two distinct components, the abstract STF file format realized via a specific encoding and an implementation of the SEDRIS Transmittal API capable of accessing the data as required by the specific encoding. These components allow users to write to, and read from, STF transmittals.

To create a new transmittal in a specific encoding of the STF or to access an existing transmittal created using a specific encoding of the STF file format, the SEDRIS Transmittal API is used.

Role of the STF

The abstract STF is the standard interchange mechanism for SEDRIS transmittals. The STF is not a library or repository of databases, just as SEDRIS is not a library or repository of databases. The abstract STF is realized by encoding the abstract STF into specific elements in one or more files.

A data producer can provide a SEDRIS transmittal using two different approaches. The first approach, and possibly the simplest approach, is to provide a transmittal in one of the standardized encodings of the STF. A consumer application can then read the data on any platform using the SEDRIS Transmittal API. The second approach is to provide a special, possibly platform specific, implementation of the SEDRIS Transmittal API. This special SEDRIS Transmittal API obtains its data from some source other than STF files. The user then has the choice of either reading directly from this particular API implementation or converting the transmittal into an STF transmittal.

Design Goals and Issues

The following design goals have been followed for the STF.

  • The design shall be platform independent.
  • Everything in the SEDRIS data model shall be able to be captured, but not necessarily using the same structures.
  • Compacting the data shall be allowed, as long as it is lossless.
  • The STF shall be as efficient as possible, both when reading and when writing.
  • The STF shall be transparent to the application user. Thus the actual underlying format could be changed and modified without affecting the user.
  • Existing standards shall be used for external resources.

Using an STF

Accessing an STF

A transmittal contained within an STF file set may be created or accessed by a SEDRIS application that implements the SEDRIS Transmittal API. The functions of the Transmittal API can open the transmittal, add and remove elements, and perform searches. SEDRIS applications shall not differentiate between an in-memory SEDRIS transmittal and a transmittal encoded in STF.

Converting a non-STF Transmittal to STF

Producers use an implementation of the Transmittal API capable of understanding an STF to create and/or modify an STF. The producer will also need an implementation of the Transmittal API capable of reading a non-STF transmittal. The Transmittal API is able to distinguish between the types of transmittals at the time that a transmittal is opened.

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Last updated: July 6, 2007