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are desired characteristics of a NMN access system.

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Major categories and classes used for the inventory exercise. Items in
boldface type represent desired characteristics of a NMN access system.

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Results for the inventory exercise. Values in boldface are desired
characteristics of a NMN access system.

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**Appendix 5-2 -- Examples of Federal Information-Exchange Networks
Based On Web Services**

There is as of this date no unified web service network standard
recognized across the governmental or environmental communities.

-   The Departments of Defense and Homeland Security are developing a
    National Information Exchange Model (<http://niem.gov/> ).

-   Environment Canada is developing web services to automate data
    exchange
    (<http://www.waterquality.ec.gc.ca/EN/navigation/10195/Search/webservice.htm>).

#### US Centers for Disease Control (CDC) developed a Public Health Information Network (PHIN - [**http://www.cdc.gov/phin/index.html**](http://www.cdc.gov/phin/index.html)). CDC is now engaged with EPA and state and local health and environmental agencies to develop an Environmental Public Health Tracking Network (EPHTN - [**http://www.cdc.gov/nceh/tracking/network.htm**](http://www.cdc.gov/nceh/tracking/network.htm)). 

It is likely that these and other networks have unique requirements that
rule out such a unified standard. It is also possible that a unified
standard will emerge. In either case, it will be necessary for some
organizations to develop the ability to communicate information across
and between networks, as is being demonstrated in the EPHTN. One of the
challenges the EPHTN faces is developing the ability to communicate
between differing networks of web services -- PHIN and the Exchange
Network.

#### 5-2.1 A Working Example: The National Environmental Information Exchange Network

Arguably the most mature web services network suitable to the task of
delivering water quality information is the EPA National Environmental
Information Exchange Network (herein referred to as "Exchange
Network").The Exchange Network uses XML, web services, and common data
standards to overcome system incompatibility, allowing partners to
securely and automatically exchange environmental data
(<http://www.exchangenetwork.net/basics/purpose.htm>).

Partners on the Exchange Network establish and maintain servers called
Network Nodes that are securely connected to the Internet. A Node is a
partner\'s single point of presence on the Exchange Network and serves
as the exchange point for all data requests and submissions. Network
Nodes automatically listen for and submit requests for data from other
information trading partners and then deliver or publish the data based
upon pre-described methods. Nodes are secure and authenticate all
requests for data to ensure they are coming from an authorized trading
partner. Software applications continue to be developed to interact with
nodes in a manual way, sending and/or receiving data depending on the
level of authorization. In this way non-node partners can be authorized
to submit data to node partners, and the general public may be allowed
to search and retrieve data from node partners.

The Exchange Network works because partners agree to use a common
vocabulary to define data exchanges. Incorporating data standards
developed by the [Environmental Data Standards
Council](http://www.envdatastandards.net/), trading partners develop XML
schemas and Data Exchange Templates (DETs) that standardize and identify
the way information is shared, so partners can obtain and understand the
data they need when they need it. Flow Configuration Documents (FCDs)
describe the web services used to deliver or publish data for each
defined data exchange and trading partner agreements (TPAs) specify how
the data will be exchanged as well as the format, frequency, and other
related issues.

A working example of an Exchange Network data flow is the Pacific
Northwest Water Quality Data Exchange (PNWWQX), which connects nodes
hosted by the environmental agencies of EPA Region 10 (Alaska, Idaho,
Oregon, and Washington) and offers a host database for organizations
without the capacity to host a network node. Since mid-2004 the PNWWQX
has offered public access to biological population, biological tissue,
sediment, soil, and water data
(<http://www.ecy.wa.gov/pnwdx/pnwdx_main.htm>).

**5-2.2 EPA Water Quality Exchange**

![](media/image1.wmf){width="6.0in" height="4.125196850393701in"}EPA
Office of Water is developing a new data management strategy, including
the development of Office of Water Water Quality Exchange (OWWQX) web
services to exchange and publish water quality monitoring data. OWWQX
will join with EPA's Storage and Retrieval (STORET) database and Central
Data Warehouse as a means to allow organizations to serve data in a
common metadata format and offer access to redundant archiving services.
The proposed OWWQX system may provide a prototype for the NMN system
([Figure 5B-1](../../fig5.1.doc)).