zeta.handler
Class GetClientHandler

java.lang.Object
  |
  +--zeta.handler.GetClientHandler

All Implemented Interfaces:

GetHandler

public class GetClientHandler

extends java.lang.Object

implements GetHandler

Handles a GET request for the needed environment of a task. The request must contains the following parameters:

• task - name of the task.
• hostname - name of the host of the resource provider.
• hostaddr - TCP/IP address of the host of the resource provider.
• os_name - name of the operating system of the resource provider.
• os_version - version of the operating system of the resource provider.
• os_arch - processor architecture of the requested resource.
• files - list of local files of the resource which are separated by comma; may be truncated if the list is lager than 900 characters.

The response contains a ZIP file with digital signatures 'signature.txt' and the needed environment, e.g. libraries. The environment is generated by the following algorithm:

1. Creates an empty ZIP file and add all digital signatures.
2. Checks if the requested resource which is defined by hostname and hostaddr can retrieve an environment for computation.
3. Checks if the requested resource which is defined by hostname can retrieve an environment for computation.
4. Checks if an unregistered resource can retrieve an environment for computation.
5. Add all programs to the ZIP file which are specified by the task_id, os_name, os_arch and the local files depend on last update of the requested resource. Note: Programs are added earlier in the ZIP file which are platform independent.
6. Update the parameters files, hostaddr, os_name, os_version, os_arch with the current timestamt on the back-end database for the requested resource.

Field Summary

private java.lang.String	contentLastZip1 Filenames of one last transferred ZIP file.
private java.lang.String	contentLastZip2 Filenames of one last transferred ZIP file.
private static java.util.Map	lastKeys Queue containing the keys of the last 1000 requested clients.
(package private) long	lastRefreshSignature Timestamp in milliseconds when the last refresh of the signature occurs.
private static java.util.TreeMap	lastTimestampsOfKeys
private java.io.ByteArrayOutputStream	lastZip1 Data of one last transferred ZIP file.
private java.io.ByteArrayOutputStream	lastZip2 Data of one last transferred ZIP file.
private static int	MAX_QUEUE_KEY_SIZE
private java.util.List	programs List of the current programs except the file 'signature.txt': task_id,name,os_name,os_arch,last_update where size = 0 mod 5
private ZetaServlet	servlet Servlet which owns this handler.
private java.sql.Timestamp	signatureLastUpdate Timestamp of the last update of the file 'signature.txt'.
private java.io.ByteArrayOutputStream	signatureStream Data of the file 'signature.txt'.
private java.lang.String	signatureVersion Version of the file 'signature.txt'.
private int	usageLastZip1 Number of using lastZip1.
private int	usageLastZip2 Number of using lastZip2.

Constructor Summary

GetClientHandler(ZetaServlet servlet)

Method Summary

void	doGet(javax.servlet.http.HttpServletRequest req, javax.servlet.http.HttpServletResponse resp) Handles a GET request for the needed environment of a task.
(package private) static long	getKeyTimestamp(java.lang.String key) Checks if the specified key of a client retrieved an environment of the last 1000 clients.
private static void	putKey(java.lang.String key) Stores the specified key of a client on a queue for at least 10 minutes.
private boolean	refreshSignature(java.sql.Statement stmt)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

MAX_QUEUE_KEY_SIZE

private static final int MAX_QUEUE_KEY_SIZE

See Also:

Constant Field Values

lastKeys

private static java.util.Map lastKeys

Queue containing the keys of the last 1000 requested clients.

lastTimestampsOfKeys

private static java.util.TreeMap lastTimestampsOfKeys

lastRefreshSignature

long lastRefreshSignature

Timestamp in milliseconds when the last refresh of the signature occurs.

signatureVersion

private java.lang.String signatureVersion

Version of the file 'signature.txt'.

signatureLastUpdate

private java.sql.Timestamp signatureLastUpdate

Timestamp of the last update of the file 'signature.txt'.

signatureStream

private java.io.ByteArrayOutputStream signatureStream

Data of the file 'signature.txt'.

programs

private java.util.List programs

List of the current programs except the file 'signature.txt': task_id,name,os_name,os_arch,last_update where size = 0 mod 5

contentLastZip1

private java.lang.String contentLastZip1

Filenames of one last transferred ZIP file.

contentLastZip2

private java.lang.String contentLastZip2

Filenames of one last transferred ZIP file.

usageLastZip1

private int usageLastZip1

Number of using lastZip1.

usageLastZip2

private int usageLastZip2

Number of using lastZip2.

lastZip1

private java.io.ByteArrayOutputStream lastZip1

Data of one last transferred ZIP file.

lastZip2

private java.io.ByteArrayOutputStream lastZip2

Data of one last transferred ZIP file.

servlet

private ZetaServlet servlet

Servlet which owns this handler.

Constructor Detail

GetClientHandler

public GetClientHandler(ZetaServlet servlet)

Parameters:

servlet - servlet which owns this handler.

Method Detail

doGet

public void doGet(javax.servlet.http.HttpServletRequest req,
                  javax.servlet.http.HttpServletResponse resp)
           throws javax.servlet.ServletException,
                  java.sql.SQLException,
                  java.io.IOException

Handles a GET request for the needed environment of a task. The request req must contains the following parameters:

• task - name of the task.
• hostname - name of the host of the resource provider.
• hostaddr - TCP/IP address of the host of the resource provider.
• os_name - name of the operating system of the resource provider.
• os_version - version of the operating system of the resource provider.
• os_arch - processor architecture of the requested resource.
• files - list of local files of the resource which are separated by comma; may be truncated if the list is lager than 900 characters.

The response resp contains a ZIP file with digital signatures 'signature.txt' and the needed environment, e.g. libraries.

Specified by:

doGet in interface GetHandler

javax.servlet.ServletException

java.sql.SQLException

java.io.IOException

refreshSignature

private boolean refreshSignature(java.sql.Statement stmt)
                          throws java.io.IOException,
                                 javax.servlet.ServletException,
                                 java.sql.SQLException

java.io.IOException

javax.servlet.ServletException

java.sql.SQLException

putKey

private static void putKey(java.lang.String key)

Stores the specified key of a client on a queue for at least 10 minutes.

Parameters:

key - key of a client which retrieved an environment

getKeyTimestamp

static long getKeyTimestamp(java.lang.String key)

Checks if the specified key of a client retrieved an environment of the last 1000 clients.

Parameters:

key - key of a client which retrieved an environment

Returns:

timestamp when the client with the specified key retrieved an environment of the last 1000 clients, 0 if this key is not one of the last 1000 clients.