uk.ac.starlink.vo

Class UserAgentUtil

java.lang.Object

uk.ac.starlink.vo.UserAgentUtil

public class UserAgentUtil
extends Object

Utilities for manipulating the HTTP User-Agent header from the JVM, following IVOA usage conventions. These conventions are codified in the SoftID IVOA Note.

Typical usage for a validator client would be:

   String uaComment = UserAgentUtil.COMMENT_TEST;   // "(IVOA-test)"
   UserAgentUtil.pushUserAgentToken( uaComment );
   ... do validation ...
   UserAgentUtil.popUserAgentToken( uaComment );
 

Since:

12 Apr 2019

Author:

Mark Taylor

See Also:

RFC 7231 sec 5.5.3, NOTE-softid-1.0

Field Summary

Fields

Modifier and Type	Field and Description
static String	AGENT_PROPNAME System property that can be used to manipulate the UserAgent header.
static String	COMMENT_COPY Comment token indicating client performs VO copy/mirror/harvest.
static String	COMMENT_TEST Comment token indicating client performs VO test/monitor/validate.
static String	IVOA_PREFIX String prefixed to purpose verb to introduce IVOA operation comment.
static String	PURPOSE_COPY Purpose verb indicating copying/mirroring/harvesting: "copy".
static String	PURPOSE_TEST Purpose verb indicating testing/monitoring/validation: "test".

Method Summary

Modifier and Type	Method and Description
static String	createOpPurposeComment(String purpose, String extra) Assembles a string of the form (IVOA-<purpose> <extra>).
static String[]	parseProducts(String productsTxt) Parses a products string as found in the HTTP User-Agent or Server header.
static void	popUserAgentToken(String token) Removes a token/comment from the currently-used User-Agent string.
static void	pushUserAgentToken(String token) Appends a token/comment to the currently used User-Agent string.

Methods inherited from class java.lang.Object

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

Field Detail

PURPOSE_TEST

public static final String PURPOSE_TEST

Purpose verb indicating testing/monitoring/validation: "test".

See Also:

Constant Field Values

PURPOSE_COPY

public static final String PURPOSE_COPY

Purpose verb indicating copying/mirroring/harvesting: "copy".

See Also:

Constant Field Values

IVOA_PREFIX

public static final String IVOA_PREFIX

String prefixed to purpose verb to introduce IVOA operation comment.

See Also:

Constant Field Values

COMMENT_TEST

public static final String COMMENT_TEST

Comment token indicating client performs VO test/monitor/validate.

COMMENT_COPY

public static final String COMMENT_COPY

Comment token indicating client performs VO copy/mirror/harvest.

AGENT_PROPNAME

public static final String AGENT_PROPNAME

System property that can be used to manipulate the UserAgent header.

See Also:

Constant Field Values

Method Detail

pushUserAgentToken

public static void pushUserAgentToken(String token)

Appends a token/comment to the currently used User-Agent string. This does not overwrite existing text, which is in general useful.

Parameters:

token - string to add

popUserAgentToken

public static void popUserAgentToken(String token)

Removes a token/comment from the currently-used User-Agent string. This only has effect if the given token is at the end of the current list, that is if it has just been added. If it's not present or not at the end, a warning is logged and there is no other effect.

Parameters:

token - previously added string to remove

createOpPurposeComment

public static String createOpPurposeComment(String purpose,
                                            String extra)

Assembles a string of the form (IVOA-<purpose> <extra>).

Parameters:

purpose - operational purpose string; recommended values are PURPOSE_* static members of this class

extra - free form additional text excluding "(" or ")"; may be null

Returns:

string suitable for User-Agent header comment

Throws:

IllegalArgumentException - if rudimentary syntax checking detects errors

parseProducts

public static String[] parseProducts(String productsTxt)

Parses a products string as found in the HTTP User-Agent or Server header. See RFC 7231 sec 5.5.3 and RFC 7230 sec 3.2.6 for the relevant syntax productions.

Parameters:

productsTxt - string giving product and comment tokens as found in User-Agent or Server header

Returns:

array of tokens; each may be either a product or a comment; comments start with a "("

Throws:

IllegalArgumentException - if the syntax is not as required