Searching

The main interface for searching is provided by OpenSearch using various extensions including the Geo and Time Extensions, the Extension for Earth Observation as well as the CEOS OpenSearch Best Practice Document.

The OpenSearch URL endpoints are:

• /opensearch: Main service description

• /opensearch/<format>: Search for collections in a specific format

• /opensearch/collections/<collection-id>: Collection specific description

• /opensearch/collections/<collection-id>/<format>: Search for products in a collection in that format

Responses

The description related endpoints provide an OpenSearch Description Document (OSDD). This XML based file format describes general service metadata and various access URL templates.

These URL objects provide templates that can be filled with parameters to submit actual metadata queries. Depending on the used URL, the search result is returned in one of the following formats:

• atom: Atom syndication format

• rss: RSS

• html: HTML

• kml: Keyhole Markup Language

• json: GeoJSON

The resulting items in that result document can be paged. Specific pages can be retrieved using the offset and count parameters. Additionally, the response contains links to the first, last, next, and previous pages of the result set.

The results of the search depend on the type of object being searched. For the collection search, the result items are collection descriptions of all matched collections encoded in the selected format. Each description contains a link to its own specific OSDD document.

In product searches, the result document items are descriptions of products, containing links to thumbnails, browses, and product specific services such as WMS or WCS. Additionally it contains the products acquisition footprint and time stamp.

Filters

The URL templates for both the collection and the record search allow to pass parameters that control the query and shape of the search. The following table shows all parameters available for both collection and product searches:

Parameter	Description
startIndex	The index offset of the items. Used to get subsets of a result set
count	The number of records for each page
start	The start time stamp for the time range
end	The end time stamp for the time range
timerel	The semantic of the time range. Either intersects, contains, disjoint, or equals
bbox	The geographic bounding box expressed as min-lon, min-lat, max-lon, max-lat in WGS84 coordinates
geom	A WKT encoded geometry for a geographic search
lon	The longitude component of point/radius searches
lat	The latitude component of point/radius searches
r	The radious in metres of point/radius searches
georel	The semantic of the geometry filter. One of intersects, contains, or disjoint

The following parameters are only available in product searches in addition to the general search parameters:

Parameter	Description
uid	Filter on identifier
cloudCover	Cloud cover filter. Either a specific value or an interval of values. Values between 0-100

The available parameters depend on the configuration made by the operator.

Samples responses for each of the four URL endpoints are provided in the Searching section of the sample_requests chapter.

Continue reading about the provided Downloading services.