Rob Hebron Consulting

I’ve published my first Android App – MyLoc. It’s a more polished version of an app I wrote for myself to keep track of where I’ve been without needing to sign up for any service that would be storing my data.

The way it works is that it wakes up every so often, gets a GPS fix (or falls back to a network fix if GPS is unavailable) and sends an email with my location to one or more email addresses. This email can include a map (downloaded from Google Maps), and an approximate address (reverse geo-coded by Google). Retrieving the map, the address and sending emails is all done on the phone rather than by a webapp hosted on some server. The emails are sent through a Gmail account (which could be the user’s main Gmail account, or a secondary one). I chose Gmail because the vast majority of Android users are likely to have an account already, and so it would be easiest for the largest number of people.

The reason I designed it to work like this is that, while I’m interested in keeping track of where I’ve been, I don’t want to be running the GPS receiver all the time as it drains battery. Also, once set up I want it to be completely hands-off. I have it set to get my location and send emails every hour and this is fine for when I want to remind myself of where I’ve been. The delay between updates can be set to as little as 10 minutes.

I think people could find it useful:

• As a reminder of where they’ve been
• To let other people know progress on a trip, or in a sporting event (marathon, triathon etc)
• As a safety net where I’m resposible for a group of people, sending out location to a trusted third party on a regular basis

I’m sure there are other uses, and I’m going to be adding functionality to it pretty regularly, so hopefully you’ll find a use for it.

I’ve recently been putting together some web applications whcih use Spring Workflow and Spring Security. I originally implemneted them without any external components, but I soon had a requirement to allow authentication to be handled by another service (the Shbboleth Apache module), while authorisation would continue to be handled by Spring security using LDAP groups. Below is a Spring Security configuration file that pulls all this together.

Note that Spring expects the REMOTE_USER username to come through in a request header, not an environment variable as Apache normally does. To do this you need to use mod_rewrite to inject the header using these directives:

RewriteEngine On
RewriteCond %{LA-U:REMOTE_USER} (.+)
RewriteRule .* – [E=RU:%1]
RequestHeader set REMOTE_USER %{RU}e

Spring config file

This config uses beans which ship with Spring Security 2.0.x.

<beans xmlns=”http://www.springframework.org/schema/beans”
xmlns:s=”http://www.springframework.org/schema/security”
xmlns:xsi=”http://www.w3.org/2001/XMLSchema-instance”
xsi:schemaLocation=”http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.0.xsd
http://www.springframework.org/schema/security http://www.springframework.org/schema/security/spring-security-2.0.1.xsd”>

<s:http>

<s:intercept-url pattern=”/work/**” access=”ROLE_GROUPERUSERS,ROLE_GROUPERADMINS” />
<s:form-login login-page=’/login.html’/>

<s:anonymous />
<s:logout />
</s:http>

<!– Pre auth –>

<bean id=”siteminderFilter”>
<s:custom-filter position=”PRE_AUTH_FILTER” />
<property name=”principalRequestHeader” value=”REMOTE_USER”/>
<property name=”authenticationManager” ref=”authenticationManager” />
</bean>

<bean id=”preauthAuthProvider”>
<s:custom-authentication-provider />
<property name=”preAuthenticatedUserDetailsService”>
<bean id=”userDetailsServiceWrapper”>
<property name=”userDetailsService” ref=”ldapUserDetailsService”/>
</bean>
</property>
</bean>
<s:authentication-manager alias=”authenticationManager” />
<bean id=”ldapUserDetailsService”>
<constructor-arg index=”0″>
<ref local=”filterBasedLdapUserSearch”/>
</constructor-arg>
<constructor-arg index=”1″>
<ref local=”ldapGroupsPopulator”/>
</constructor-arg>
</bean>
<bean id=”filterBasedLdapUserSearch”>
<constructor-arg index=”0″>
<value>o=Accounts</value>
</constructor-arg>
<constructor-arg index=”1″>
<value>(cn={0})</value>
</constructor-arg>
<constructor-arg index=”2″>
<ref local=”contextSource”/>
</constructor-arg>
<property name=”searchSubtree” value=”true”/>
</bean>
<bean id=”ldapGroupsPopulator”>
<constructor-arg>
<ref bean=”contextSource”/>
</constructor-arg>
<constructor-arg>
<value>ou=Groups,o=Resources</value>
</constructor-arg>
<property name=”searchSubtree” value=”true”/>
<property name=”groupRoleAttribute” value=”cn”/>
<property name=”groupSearchFilter” value=”(member={0})”/>
<property name=”rolePrefix” value=”ROLE_”/>
</bean>

<bean id=”contextSource”>
<property name=”url” value=”ldap://127.0.0.1:389/”/>
<property name=”userDn” value=”cn=admin,o=users”/>
<property name=”password” value=”password”/>
</bean>
<!–  end preauth –>

</beans>