Table of Contents - APTAStandards.com

eXtensible Markup Language (XML) is a standard for the communication
of
information in a text format that is structured, well formed and validated against a
model (schema). XML grew out of Standard Generalized Mark Up Language
(SGML), a
presentation-oriented language designed to display information
in printed and
electronic form in a wide variety of formats. Hyper Text Mark Up Language (HTML),
the language of web browsers, is another cousin of XML. XML focuses on data
structures and document formatting. The data can be validated for both structure and
content, to whatever extent desired by the schema designer.
OFX is based on XML, a “tagged” protocol, where each aggregate and data element has
a name. The data is presented as a serial string, where
each aggregate, or data element
is preceded by a “” and followed by a ““. Naming of tags
within an XML schema is completely up to the user, as is their organization
and
structure.
The entire message strings can be encrypted or compressed, or individual
aggregates can be encrypted. All that is required is that both the sender and the
receiver operate the same schema to define the contents
of the messages. This makes
communication among different computer architectures
very simple, since they only
have to agree on a character representation (normally ASCII) and a schema. Binary,
Boolean, decimal and bitwise data are all represented as character data during
transmission. Attributes can further define a tag’s values
by permitting defaults and
mandating content or enumerations of acceptable
values. For example, a “rideroute”
aggregate might consi st of a bus id, a route id and a direction
as illustrated in Exhibit
4.3-1.
Exhibit 4.3-1 Example Rideroute Aggregate
1456
2671
inbound
In order to communicate among a number of parties or organizations, schemas are
being standardized within many industries and groups with common needs. One such
schema that defines tags attributes and aggregates for the financial community is OFX.
The
Open Financial Exchange specification is publicly available for implementation by
any financial institution or vendor. As of September 2003, over 2400 banks and
brokerages, as well as major payroll processing companies support OFX. The latest
version of OFX as of July 2004 is version 2.0.1.
4.3.2 Applicability to UTFS Effort
Althou gh a well-defined and widely implemented specification, OFX, in its current
form, does not provide schemas that are applicable to the efforts of the UTFS.
However, it certainly serves as a viable model for the development of a similar transit
industry standard based on XML. Even though XML is admittedly bulky, it should
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