This chapter provides description APS Catalog API features. It is divided into the following sections:
A client interacts with APS Catalog by issuing HTTP GET/POST requests, and retrieving HTTP packets with status codes and APS Catalog resources. A resource can be a binary file (for example, a package) or an XML-based message. Each XML message conforms to one of the following formats:
Atom feed [RFC 4287] with the following extensions:
- OpenSearch 1.1
- Feed paging [RFC 5005]
- Native APS Catalog extensions describing APS package metadata
XHTML format that describes APS catalog structure.
Native XML-based format that describes APS catalog structure. For details, refer to APS Catalog Resources.
This section describes resources that a client accesses through APS Catalog API. The resources are divided into the following types:
APS Catalog represents each package as three resources: package bits, package metadata, and package resources.
The following diagram depicts the organization of APS Catalog resources:
The diagram shows that all resources are directly or indirectly linked with indexes - read-only XHTML data that hold information about the APS Catalog hierarchy structure.
The following table shows references that are provided by a specific index.
|Index name||Link to Parent Index||Link to Child indexes||Feed link||Link to package bits||Link to package metadata||Link to package certificate||Link to Package resources|
|Application Version index|
|Package Version index|
In terms of file systems, indexes describe APS Catalog directories, each containing links to its content, parent directory, and subdirectories. A client can request an index at a specific URL. For details on index URLs and elements included in indexes, refer to Indexes of the API Reference.
As noted, almost every index has a feed link. If indexes represent the structure of APS Catalog, feeds represent its content. More precisely, a feed is composed of entries, each providing details on a single package. The details include a package name, vendor, version, etc.
APS Catalog provides five read-only Atom feeds:
A client can request a feed at the URL retrieved from a corresponding index. There are two features of how APS Catalog operates with feed requests.
For details on paged feeds, refer to [RFC 5005].
A client can limit the number of entries in a requested feed by adding specific arguments to the feed request. These arguments are feed specific. APS Catalog stores the request arguments in resources called search description documents. Hereafter in this guide, we will refer to these resources as to search descriptions. One search description corresponds to a single feed. Search descriptions conform to the search description format. For details on search descriptions format, see OpenSearch specification.
APS Catalog provides the following search descriptions:
As can be seen from the list, only four feeds have search descriptions, namely: Repository, Vendor, Application, and Application Version.
A client can request a search description at a specific URL. For details on search description URLs and XML structure, refer to Search Descriptions of the API Reference.
To use the API, a client sends HTTP requests to APS Catalog that instructs it to perform a RETRIEVE or ADD operation over a resource.
APS Catalog processes feed requests differently from other requests. For details, refer to APS Catalog Resources
For details on the Add operations, refer to Managing APS Catalog Contents.