HTTP Connection Bundle

The HTTP Connection Bundle wraps a connection factory implementing the http scheme. This scheme provides means for communication over HTTP. It can be used by bundles which need to establish connection with bundles running on the local or remote framework.

Contents:

• Bundle Information
  • Bundle JAR
  • Import
  • Export
• HTTP Connection Factory Service
  • HTTP Uniform Resource Identifiers (URIs)
    • Server-Side URIs
    • Client-Side URIs
  • Using the Service
• System Properties
• References

Bundle Information

Bundle JAR

The JAR file of this bundle is httpconn.jar, located in the bundles folder.

Import

Note: The HTTP Connection Bundle uses the HTTP Service for transferring information over HTTP. Hence, you cannot start the bundle if the HTTP Bundle is not active too.

Note: If the bundle is started on the Standard Version of the framework, the connection APIs are exported by the Connector Service Bundle. If the bundle is started on the Connector Version of the framework, these APIs are exported by the System Bundle.

Note: If the bundle is started on ProSyst mBS, the com.prosyst.util.ref package is exported by the ProSyst Util Bundle. If it is started on an OSGi framework provided by another vendor, the package is exported by the ProSyst Util Full Bundle.

Export

None.

HTTP Connection Factory Service

This service publishes the org.osgi.service.io.ConnectionFactory interface and represents a connection factory for the OSGi communication model, described in the OSGi IO Connector Service Specification. It is used by the IO Connector Service (exported by the Connector Service Bundle or by the System Bundle, depending on the version of the framework) for creating connections over the http scheme.

The HTTP Connection Factory handles connection requests for the http scheme. It provides communication over the HTTP v 1.1 protocol. This means that the keep connection alive option and proxy management are implemented.

The HTTP Connection Factory supports two connection types:

• Server side connection - This type of connection is meant to open server-side socket for waiting HTTP communication. It registers a servlet with the HTTP Service with alias extracted from the passed server http URI. The role of this servlet is to manage connection requests from bundles needing communication over the http scheme. When a request is received, the servlet creates a connection. The actual transfer of messages, however, is handled by the HTTP Service. The server connection implements javax.microedition.io.StreamConnection and javax.microedition.io.StreamConnectionNotifier.
• Client side connection - It is used when a bundle wants to establish a connection to a server-side HTTP socket. This means that a server side connection must have already been opened on the desired host and port (no matter if the port has been opened through the HTTP Connection Factory Service or in any other way). If some error occurs, IOException is thrown. The created connection implements javax.microedition.io.StreamConnection and org.mbs.services.io.ConnectionNotifier.

  Creating a client side connection requires passing a client http URI to the IO Connector Service.

Note: If the connection factory is unregistered, all created connections are closed.

HTTP Uniform Resource Identifiers (URIs)

All URIs processed by the HTTP Connection Factory must start with "http:". However, there is a slight difference between client side URIs and server side URIs.

Server-Side URIs

A valid server URI must have the following syntax:

http:/<alias>

where <alias> stands for the HTTP alias with which the servlet registered by the server HTTP connection is created.

For example, a server http URI may look like this:

http:/http_serv_alias

Client-Side URIs

A client connection URI must have the following form:

http://<host>[:<port>]/<alias>

where <host> stands for the machine on which the server socket is waiting. The [..] brackets represent an optional part. They are not part of the URI itself. If the port occupied by the server is different from the default value: 80, it must be passed to the URI. If the occupied port is 80, it may be omitted from the URI. The <alias> part represents the HTTP alias under which the server connection has registered its servlet.

For example, the client URI may look like this:

http://127.0.0.1:8080/http_serv_alias

Note: Some parts of the URI are case sensitive! For details, refer to RFC 2396.

Using the Service

If you want to use the HTTP Connection Factory as an underlying transport implementation for your connections, you must invoke the IO Connector Service, exported by the Connector Service Bundle/System Bundle, and pass an http URI to its open method. For more information refer to the Connector Service Bundle description. You can manage the created connections using the methods of the respective subinterfaces of javax.microedition.io.Connection. See Client-side connections and Server side connections for details.

System Properties

The HTTP Connection Bundle owns a number of user-definable system properties. The first two serve for debug purposes. The rest of the properties are applied when using a proxy.

If you set/change these properties after the bundle has been activated, you must restart it so that it will accept the new values.

References

• OSGi IO Connector Service Specification (distributed as part of the OSGi Service Platform Service Compendium, Release 4)
• OSGi Communication API
• Generic Connection API
• ProSyst Communication API
• RFC 2396 (Uniform Resource Identifiers (URI): Generic Syntax)
• Connector Service Bundle Description
• System Bundle Description
• HTTP Bundle Description

Connection Bundles