METADATA SERVICES

About metadata

Whether you realize it or not, you've seen metadata before. There's metadata for a wide variety of things, with varying levels of detail. The nutritional information on the label of a can of soup is metadata. A department store catalog is metadata. The price sticker on a new car is metadata. Anything that describes something else can be thought of as metadata.

Metadata is useful because it tells you about something without having that something. For example, you might browse through a store catalog before deciding to make a purchase. The metadata about the items in the catalog give you valuable information such as price, size, and material to help you determine whether the item is right for you.

Metadata for geographic data is often described as data about data. Metadata for geographic data typically describes the content, quality, type, collection date, and spatial location of the actual data. Looking at metadata can help you determine whether a particular dataset is appropriate for your use. In fact, it' s often easier to judge the suitability of the data from its metadata than by examining the actual data itself. This is because metadata is generally much smaller and easier to share than the actual data.

Full metadata documentation, Creating_Metadata_Services.pdf, was not available at the time of release. Check the documentation download area on the ESRI support site for this document. Go to http://support.esri.com, click Knowledge Base, click Product Documentation, then click ArcIMS. This guide tells how to use ArcIMS, with ArcGIS Desktop and ArcSDE, to create a catalog of your GIS holdings that you can make available to users over the Internet. It also describes how to use Metadata Explorer, a Web application that comes with ArcIMS, for searching and viewing metadata.

About Metadata Services

A Metadata Service provides a forum for sharing metadata. If you don't have data but need some, you might search, or browse, a Metadata Service to find what you need. Similarly, if you have data that you want to share with others, you can share, or publish, it to a Metadata Service where others can see it.

Finding data

Suppose you're creating a map for a presentation and you need some basemap data to display behind the data you've collected about your study area. There are many organizations that collect geographic information and build datasets. Some organizations freely distribute their data while others may charge a small fee. The question is, how do you find that data?

The first place you might look is ESRI's Geography NetworkSM (www.geographynetwork.com). The Geography Network is a global network of geographic information users and providers. Through the Geography Network, you can access many types of geographic content including live maps, downloadable data, and more advanced services. One component of the Geography Network the Geography Network Explorer is a Metadata Service. Through the Geography Network Explorer, you can search for data by geographic location, theme such as environmental data, business data, and basemap data scale, data collected, and so on.

You can think of a Metadata Service as a geographic data search engine that you use when you want to find data. A Metadata Service works over the Internet , allowing anyone who has access to the Web to use it. The Geography Network is just one place you can go to look for data. Just as you can use different Internet search engines such as Yahoo!® you can also search different Metadata Services hosted by other organizations. If you know the Web address of those Metadata Services, you can easily search their contents for geographic data.

When you search for data on a Metadata Service, your search will yield a list of datasets that match your search criteria. You can view the complete metadata for each dataset to see if it's what you're looking for and sometimes view an interactive map. Once you decide if the data is suitable, you can use it alongside your data by downloading it and, in some instances, using it right from the Web.

Sharing data

If your organization is like most, you've invested a great deal of time and money collecting the data from which you've built your geographic database. Often, the people who build the databases aren't the same people who need to use them. So, how do you share your data with others who need it? Depending upon who needs access to your data, there are several approaches that allow you to utilize the capabilities of a Metadata Service.

- Share your data on the Geography Network The Geography Network is a good place to start. If the data you collect is not restricted to internal use and can be shared either freely or for a fee you can publish it to the Geography Network. Simply browse to www.geographynetwork.com and follow the link that allows you to become a publisher on the Geography Network. Once you ve published your metadata, anyone who searches the Geography Network will find your data if it meets their search criteria.

- Share your data on another organization's Metadata Service Any organization that has ArcIMS can host a Metadata Service. If you have access to this service, you can publish your metadata to it. Anyone who can use that service will then be able to see the data you've shared. Like sharing your data on the Geography Network, this option requires that you have access to the Internet and have been granted permission to publish to the Metadata Service.

- Share your data on your own Metadata Service. By building your own Metadata Service, you have full control over it. You can control who can search and browse its contents as well as who can publish metadata to it. For example, you might create a Metadata Service to facilitate data sharing between departments within your organization. You could configure your system so that only people within your organization could access it. Later, if you choose to give people outside of your organization access to your service, you can easily do so.

Creating Metadata Services

Once you've decided that the best way to share your organization's data is to create your own Metadata Service, creating one is actually straightforward. But before you create your service, there are a few things you should think about.

� Who will use your Metadata Service?

� Will you allow people outside of your organization to publish to it or view its contents?

� How many metadata documents will be published to your service? This will impact the amount of storage space required in your database.

� How many people will be using the service at the same time?

� How many people will be publishing to your service versus just browsing it? It takes longer to publish documents and puts more load on the system.

� Do you need to create more than one Metadata Service? If you want to keep metadata documents from different groups completely separate, you may choose to create more than one Metadata Service.

Your answers to these questions as well as your own will help determine how you will need to set up your Metadata Service.

SOURCE : http://www.jakarta.go.id/peta/imsix/ArcIMS/Manager/Help/metadata/what_is_a_mdata_svc.htm

When should you consider Metadata Services?

• Your digital collection of texts, images, audio, or video have grown beyond a few selected titles.
• You want your digital resources organized and stored for easy access and use.
• You need to share your digital content with colleagues, students, or clients.
• You want digital information accessible and safe for years, decades, or longer.
• You need to make a hidden collection of materials available over the Internet.