thredds.server.reify

Class DownloadController

java.lang.Object

thredds.server.reify.LoadCommon

thredds.server.reify.DownloadController

@Controller
 @RequestMapping(value={"/download","/restrictedAccess/download"})
public class DownloadController
extends LoadCommon

Local File Materialization for server-side computing. The tag for this controller is .../download/* or .../restrictedAccess/download

The goal for this controller is to allow external code to have the thredds server materialize a dataset into the file system .

Note that this functionality is not strictly necessary since it could all be done on the client side. Since the server is doing all of the work of converting a dataset to a file, the client does not need to have its own code for this. This means: 1. It is lightweight WRT the client 2. It is language independent

Assumptions: 1. The external code has authenticated to the thredds server using some authentication mechanism such as client-side certificates or tomcat roles. This code performs no authentication.

2. The external code is running on the same machine as the thredds server, or at least has a common file system so that file system writes by thredds are visible to the external code.

WARNING: In order to support downloading of non-file datasets (e.g. via DAP2 or DAP4) this controller will re-call the server to obtain the output of the request. Experimentation shows this is not a problem. Circularity is tested to ensure the no download loop occurs.

Issues: 1. What file formats are allowed for materialized datasets? - Currently only netcdf-3 (classic) and netcdf-4 (enhanced).

A set of query parameters control the operation of this servlet. Note that all of the query parameter values (but not keys) are assumed to be url-encoded (%xx), so beware. Also, all return values are url-encoded. Using query parameters means that it is possible to use an Http Form to send them; see TestDownload.

Download Request ---------------- Download parameters: - request=download -- materialize a file into the download directory - format=netcdf3|netcdfd4 -- specify the download format - url={a thredds server dataset access url} -- specify the actual dataset. - target={path of the downloaded file} -- if it already exists, then it will be overwritten. Notes: 1. the host, port and servlet prefix of the url will be ignored and replaced with the "+/thredds" of the thredds server. This is to prevent attempts to use the thredds server to access external data sources, which would otherwise provide a security leak. 2. The target path must be a relative path. It is interpreted as relative to the value of a -Dtds.download.dir java flag, which must specify an absolute path to a directory into which the downloads are stored. Assuming the Tomcat server is being used, then the path must be writeable by user tomcat, which means that its owner will end up being user tomcat or at least tomcat must be in the group assigned to this directory.

Return value: download=

Misc Parameters: - testinfo={testing info} -- for testing purposes

Inquire Request ---------------- Download parameters: - request=inquire -- Inquire about various parameters - inquire={semicolon separated arguments} -- Inquire about the default download dir

Return value: ={value of the requested key}; one key-value pair per line.

Nested Class Summary

Nested classes/interfaces inherited from class thredds.server.reify.LoadCommon

LoadCommon.SendError

Field Summary

Fields

Modifier and Type	Field and Description
protected ucar.nc2.write.Nc4Chunking	chunking
protected static boolean	DEBUG
protected static java.lang.String	DEFAULTDOWNLOADDIR
protected static java.lang.String	DEFAULTREQUESTNAME
protected java.lang.String	downloadform
protected static java.lang.String	FILESERVERSERVLET
protected thredds.server.reify.DownloadParameters	params
protected ucar.nc2.write.Nc4Chunking.Strategy	strategy

Fields inherited from class thredds.server.reify.LoadCommon

DEFAULTDOWNLOADFORM, DEFAULTSERVLETNAME, DEFAULTUPLOADFORM, downloaddir, downloaddirname, HTMLLEN, initialized, once, req, requestname, res, server, tdsContext, threddsname, uploaddir

Constructor Summary

Constructors

Constructor and Description
DownloadController()

Method Summary

Modifier and Type	Method and Description
protected java.lang.String	buildForm(java.lang.String msg)
protected boolean	canCopy(java.lang.String truepath, thredds.server.reify.LoadCommon.FileFormat targetformat)
protected java.lang.String	directAccess(java.lang.String relpath, javax.servlet.http.HttpServletRequest req, javax.servlet.http.HttpServletResponse res)
void	doGet(javax.servlet.http.HttpServletRequest req, javax.servlet.http.HttpServletResponse res)
void	doonce(javax.servlet.http.HttpServletRequest req) Invoked once on first request so that everything is available, especially Spring stuff.
protected java.lang.String	download()
protected static java.lang.String	escapeString(java.lang.String s) Given a typical string, insert backslashes before '"' and '\\' characters and control characters.
protected void	makeNetcdf3(ucar.nc2.NetcdfFile ncfile, java.lang.String target)
protected void	makeNetcdf4(ucar.nc2.NetcdfFile ncfile, java.lang.String target)
void	setup(javax.servlet.http.HttpServletRequest req, javax.servlet.http.HttpServletResponse resp)

Methods inherited from class thredds.server.reify.LoadCommon

getStackTrace, init, initOnce, inquire, mapToString, parseList, parseMap, reportRequest, sendError, sendError, sendError, sendErrorForm, sendForm, sendOK, sendReply, urlDecode, urlEncode

Methods inherited from class java.lang.Object

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

Field Detail

DEBUG

protected static final boolean DEBUG

See Also:

Constant Field Values

DEFAULTREQUESTNAME

protected static final java.lang.String DEFAULTREQUESTNAME

See Also:

Constant Field Values

DEFAULTDOWNLOADDIR

protected static final java.lang.String DEFAULTDOWNLOADDIR

See Also:

Constant Field Values

FILESERVERSERVLET

protected static final java.lang.String FILESERVERSERVLET

See Also:

Constant Field Values

strategy

protected ucar.nc2.write.Nc4Chunking.Strategy strategy

chunking

protected ucar.nc2.write.Nc4Chunking chunking

params

protected thredds.server.reify.DownloadParameters params

downloadform

protected java.lang.String downloadform

Constructor Detail

DownloadController

public DownloadController()
                   throws javax.servlet.ServletException

Throws:

javax.servlet.ServletException

Method Detail

doonce

public void doonce(javax.servlet.http.HttpServletRequest req)
            throws LoadCommon.SendError

Invoked once on first request so that everything is available, especially Spring stuff.

Throws:

LoadCommon.SendError

setup

public void setup(javax.servlet.http.HttpServletRequest req,
                  javax.servlet.http.HttpServletResponse resp)
           throws LoadCommon.SendError

Throws:

LoadCommon.SendError

doGet

@RequestMapping(value="**",
                method=GET)
public void doGet(javax.servlet.http.HttpServletRequest req,
                                                                          javax.servlet.http.HttpServletResponse res)
                                                                   throws javax.servlet.ServletException

Throws:

javax.servlet.ServletException

download

protected java.lang.String download()

Returns:

absolute path to the downloaded file

Throws:

SendError - if bad request

makeNetcdf4

protected void makeNetcdf4(ucar.nc2.NetcdfFile ncfile,
                           java.lang.String target)
                    throws java.io.IOException

Throws:

java.io.IOException

makeNetcdf3

protected void makeNetcdf3(ucar.nc2.NetcdfFile ncfile,
                           java.lang.String target)
                    throws java.io.IOException

Throws:

java.io.IOException

escapeString

protected static java.lang.String escapeString(java.lang.String s)

Given a typical string, insert backslashes before '"' and '\\' characters and control characters.

directAccess

protected java.lang.String directAccess(java.lang.String relpath,
                                        javax.servlet.http.HttpServletRequest req,
                                        javax.servlet.http.HttpServletResponse res)

canCopy

protected boolean canCopy(java.lang.String truepath,
                          thredds.server.reify.LoadCommon.FileFormat targetformat)

buildForm

protected java.lang.String buildForm(java.lang.String msg)

Specified by:

buildForm in class LoadCommon