org.acplt.oncrpc.OncRpcHttpClient

public class OncRpcHttpClient extends OncRpcClient

ONC/RPC client which communicates with ONC/RPC servers over the network using the ISO/OSI level 7 application protocol HTTP as a tunnel.

Please note that currently no standard exists about how to tunnel XDR data over HTTP connections. There are a few solutions out there, but they are more or less incompatible due to the lack of an RFC. So I'm now adding yet another proprietary solution.

The protocol which is used here is rather simple and tries to be compatible with as much firewall systems as possible. For this to achieve, both the ONC/RPC calls as well as their replies are first base64 encoded, before they are sent through the tunnel. This way, calls and replies appear to be ordinary text documents of mime type "text/plain".

Calls will appear to be something like this, carrying redirection information. Note that we do not include ONC/RPC call information in the header section, as this is already included in the ONC/RPC call itself. So including it in the header would just make it easier to play games with the header.

     CALL host name:port protocol TEA/1<CR><LF>
     B0D0EADSDEADBEEF...<CR><LF>
     ...<CR><LF>
     DEADBE==<CR><LF>

Replies do not carry the redirection head, but only the base64 encoded data of the ONC/RPC reply:

     B0D0EADSDEADBEEF...<CR><LF>
     ...<CR><LF>
     DEADBE==<CR><LF>

The decoding from the base64 encoded data is carried out by the XdrHttpDecodingStream class.

I'm not using eecks-emm-ell on purpose (net yet). While it is surely fun to play with and it has its merits, just to create yet another RPC tunnel parsing XML is still too large an overhead to accept. Despite cynics pointing out that the Internet is already that slow so that XML overhead will not be visible at all, I nevertheless disagree. On the other hand, XML would be really fine to be misused for yet another proprietary and misguided ASCII, pardon UTF-8, data format...

     <?xml version="1.0"?>
     <!DOCTYPE oncrpc-call SYSTEM "oncrpc-call.dtd">
     <oncrpc-call server="foo.bar.com" protocol="tcp">
         B0D0EADSDEADBEEF...<CR><LF>
         ...<CR><LF>
         DEADBE==<CR><LF>
     </oncrpc-call>

The answer then could be represented as follows:

     <?xml version="1.0"?>
     <!DOCTYPE oncrpc-reply SYSTEM "oncrpc-reply.dtd">
     <oncrpc-reply>
         B0D0EADSDEADBEEF...<CR><LF>
         ...<CR><LF>
         DEADBE==<CR><LF>
     </oncrpc-reply>

So it should be fairly easy to switch over to XML if someone will insist on it. Reminds me of my Xmas lecture about "Internet Technologies -- Sacred Land of the Automation Industry?"...

Version:

$Revision: 1.5 $ $Date: 2005/11/11 21:18:43 $ $State: Exp $ $Locker: $

Author:

Harald Albrecht

See Also:

Field Summary

Fields inherited from class org.acplt.oncrpc.OncRpcClient
auth, host, port, program, timeout, version, xid
Constructor Summary

Constructors

Constructor

Description

OncRpcHttpClient(String hostname, int httpPort, String cgiHandlerPath, String oncrpcHostname, int program, int version, int port, int protocol)

Constructs a new OncRpcHttpClient object, which connects to the ONC/RPC server at host for calling remote procedures of the given { program, version }.

OncRpcHttpClient(String hostname, String cgiHandlerPath, String oncrpcHostname, int program, int version, int port)

Constructs a new OncRpcHttpClient object, which connects to the ONC/RPC server at host for calling remote procedures of the given { program, version }.

OncRpcHttpClient(String hostname, String cgiHandlerPath, String oncrpcHostname, int program, int version, int port, int protocol)

Constructs a new OncRpcHttpClient object, which connects to the ONC/RPC server at host for calling remote procedures of the given { program, version }.
Method Summary

Modifier and Type

Method

Description

void

call(int procedureNumber, int versionNumber, XdrAble params, XdrAble result)

Calls a remote procedure on an ONC/RPC server.

void

close()

Close the connection to an ONC/RPC server and free all network-related resources.

String

getCharacterEncoding()

Get the character encoding for (de-)serializing strings.

String

getHostname()

Returns the host name of the HTTP server we are connected to.

int

getHttpPort()

Returns the port of the HTTP server we are connected to.

void

setCharacterEncoding(String characterEncoding)

Set the character encoding for (de-)serializing strings.

Methods inherited from class org.acplt.oncrpc.OncRpcClient
call, getAuth, getHost, getPort, getProgram, getTimeout, getVersion, newOncRpcClient, newOncRpcClient, nextXid, setAuth, setTimeout

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details
- OncRpcHttpClient
  
  public OncRpcHttpClient(String hostname, String cgiHandlerPath, String oncrpcHostname, int program, int version, int port) throws OncRpcException, IOException
  
  Constructs a new OncRpcHttpClient object, which connects to the ONC/RPC server at host for calling remote procedures of the given { program, version }. At the other end of the HTTP tunnel, TCP/IP is used to call the ONC/RPC server.
  Note that the HTTP connection is not build before the first ONC/RPC call is done through the call(int, int, org.acplt.oncrpc.XdrAble, org.acplt.oncrpc.XdrAble) method. The HTTP client tries to keep the connection alive but reconnects if necessary. Nevertheless, as it signals all failures, the caller has to handle reconnect situations -- but this is easy to achieve.
  
  Parameters:
  
  hostname - The DNS name of the host where the ONC/RPC server resides.
  
  cgiHandlerPath - The path to the CGI Handler which will redirect ONC/RPC calls to the particular ONC/RPC servers.
  
  oncrpcHostname - The DNS name of the ONC/RPC server to contact.
  
  program - Program number of the ONC/RPC server to call.
  
  version - Program version number.
  
  port - The port number where the ONC/RPC server can be contacted. If 0, then the other end of the HTTP tunnel will try to ask the portmapper at host for the port number.
  
  Throws:
  
  OncRpcException - if an ONC/RPC error occurs.
  
  IOException - if an I/O error occurs.
- OncRpcHttpClient
  
  public OncRpcHttpClient(String hostname, String cgiHandlerPath, String oncrpcHostname, int program, int version, int port, int protocol) throws OncRpcException, IOException
  
  Constructs a new OncRpcHttpClient object, which connects to the ONC/RPC server at host for calling remote procedures of the given { program, version }.
  Note that the HTTP connection is not build before the first ONC/RPC call is done through the call(int, int, org.acplt.oncrpc.XdrAble, org.acplt.oncrpc.XdrAble) method. The HTTP client tries to keep the connection alive but reconnects if necessary. Nevertheless, as it signals all failures, the caller has to handle reconnect situations -- but this is easy to achieve.
  
  Parameters:
  
  hostname - The DNS name of the host where the ONC/RPC server resides.
  
  cgiHandlerPath - The path to the CGI Handler which will redirect ONC/RPC calls to the particular ONC/RPC servers.
  
  oncrpcHostname - The DNS name of the ONC/RPC server to contact.
  
  program - Program number of the ONC/RPC server to call.
  
  version - Program version number.
  
  port - The port number where the ONC/RPC server can be contacted. If 0, then the other end of the HTTP tunnel will try to ask the portmapper at host for the port number.
  
  protocol - Transport protocol to be used by the other end of the tunnel to call the ONC/RPC server.
  
  Throws:
  
  OncRpcException - if an ONC/RPC error occurs.
  
  IOException - if an I/O error occurs.
- OncRpcHttpClient
  
  public OncRpcHttpClient(String hostname, int httpPort, String cgiHandlerPath, String oncrpcHostname, int program, int version, int port, int protocol) throws OncRpcException, IOException
  
  Constructs a new OncRpcHttpClient object, which connects to the ONC/RPC server at host for calling remote procedures of the given { program, version }.
  Note that the HTTP connection is not build before the first ONC/RPC call is done through the call(int, int, org.acplt.oncrpc.XdrAble, org.acplt.oncrpc.XdrAble) method. The HTTP client tries to keep the connection alive but reconnects if necessary. Nevertheless, as it signals all failures, the caller has to handle reconnect situations -- but this is easy to achieve.
  
  Parameters:
  
  hostname - The DNS name of the host where the ONC/RPC server resides.
  
  httpPort - The port number where the HTTP server is to be contacted.
  
  cgiHandlerPath - The path to the CGI Handler which will redirect ONC/RPC calls to the particular ONC/RPC servers.
  
  oncrpcHostname - The DNS name of the ONC/RPC server to contact.
  
  program - Program number of the ONC/RPC server to call.
  
  version - Program version number.
  
  port - The port number where the ONC/RPC server can be contacted. If 0, then the other end of the HTTP tunnel will try to ask the portmapper at host for the port number.
  
  protocol - Transport protocol to be used by the other end of the tunnel to call the ONC/RPC server.
  
  Throws:
  
  OncRpcException - if an ONC/RPC error occurs.
  
  IOException - if an I/O error occurs.
Method Details
- close
  
  public void close() throws OncRpcException
  
  Close the connection to an ONC/RPC server and free all network-related resources. Well -- at least hope, that the Java VM will sometimes free some resources. Sigh.
  
  Overrides:
  
  close in class OncRpcClient
  
  Throws:
  
  OncRpcException - if an ONC/RPC error occurs.
- call
  
  public void call(int procedureNumber, int versionNumber, XdrAble params, XdrAble result) throws OncRpcException
  
  Calls a remote procedure on an ONC/RPC server.
  FIXME: timeout control?
  
  Specified by:
  
  call in class OncRpcClient
  
  Parameters:
  
  procedureNumber - Procedure number of the procedure to call.
  
  versionNumber - Protocol version number.
  
  params - The parameters of the procedure to call, contained in an object which implements the XdrAble interface.
  
  result - The object receiving the result of the procedure call.
  
  Throws:
  
  OncRpcException - if an ONC/RPC error occurs.
- setCharacterEncoding
  
  public void setCharacterEncoding(String characterEncoding)
  
  Set the character encoding for (de-)serializing strings.
  
  Specified by:
  
  setCharacterEncoding in class OncRpcClient
  
  Parameters:
  
  characterEncoding - the encoding to use for (de-)serializing strings. If null, the system's default encoding is to be used.
- getCharacterEncoding
  
  public String getCharacterEncoding()
  
  Get the character encoding for (de-)serializing strings.
  
  Specified by:
  
  getCharacterEncoding in class OncRpcClient
  
  Returns:
  
  the encoding currently used for (de-)serializing strings. If null, then the system's default encoding is used.
- getHostname
  
  public String getHostname()
  
  Returns the host name of the HTTP server we are connected to.
  
  Returns:
  
  host name.
- getHttpPort
  
  public int getHttpPort()
  
  Returns the port of the HTTP server we are connected to.
  
  Returns:
  
  port number.

Class OncRpcHttpClient

Field Summary

Fields inherited from class org.acplt.oncrpc.OncRpcClient

Constructor Summary

Method Summary

Methods inherited from class org.acplt.oncrpc.OncRpcClient

Methods inherited from class java.lang.Object

Constructor Details

OncRpcHttpClient

OncRpcHttpClient

OncRpcHttpClient

Method Details

close

call

setCharacterEncoding

getCharacterEncoding

getHostname

getHttpPort