I have made modifications to the JIRA XML-RPC plugin 3.3-2 that provide the following additional methods for the JiraSoapService:
public RemoteIssue[] getAllLinkedIssues(String loginToken, String issueKey) throws RemotePermissionException, RemoteAuthenticationException, RemoteException;
The getAllLinkedIssues() method will simply return a link of JIRA issues linked to the issue with the given key that are viewable by the user authenticated into the Soap Service.
public RemoteIssue[] getLinkedIssues(String token, String issueKey, String linkName, boolean outward) throws RemotePermissionException, RemoteAuthenticationException, RemoteException;
The getLinkedIssues() method will return all JIRA issues associated with the given link and direction of the link of the issue with the given key that are viewable by the user authenticated into the Soap Service. The linkName is the value returned by RemoteIssueLinkType.getName().
public RemoteIssueLinkType[] getAllLinkTypes(String token) throws RemoteAuthenticationException, RemoteException;
The getAllLinkTypes() will return RemoteIssueLinkType objects for all of the link types defined in the Jira installation that this Soap Service is running on. The RemoteIssueLinkType has a name attribute, the inward description of the link, the outward description of the link and a boolean specifying if it is a system link type (ie. not user defined).
The source code is attached and I have also included with the following JIRA issue:

Comments (1)
Sep 07, 2005
Anton Mazkovoi says:
Thanks\! We'll see if we can include your extensions in JIRA 3.4.Thanks! We'll see if we can include your extensions in JIRA 3.4.