service side: interface must be optional for methods if unambiguous

[NTCoding]

If I create the service from the example, I get the following on the command line

╰─➤ qdbus org.ruby.service /org/ruby/MyInstance
signal void org.ruby.SampleInterface.SomethingJustHappened(QString toto, uint tutu)
method void org.ruby.SampleInterface.hello(QString name, QString name2)
method void org.ruby.SampleInterface.test_variant(QDBusVariant stuff)
method QString org.ruby.AnotherInterface.Reverse(QString instr)
method void org.ruby.AnotherInterface.ThatsALongMethodNameIThink()

Notice there is no introspect method. Also, I can't call any of the methods, I get the following error:

╰─➤ qdbus org.ruby.service /org/ruby/MyInstance Reverse "yay"
Error: org.freedesktop.DBus.Error.UnknownMethod
Interface "" of object "/org/ruby/MyInstance" doesn't exist

I have created multiple service, in different applications, but still keep getting this error. When the method genuinely doesn't exist, there is another different error saying it cannot be found.

[mvidner]

Thanks for the report!

• Not introspectable: yes and no

It is true that org.freedesktop.DBus.Introspectable.Introspect is missing from the qdbus output, but introspection does work, in fact qdbus uses it to get that output.

$ qdbus org.ruby.service /org/ruby/MyInstance org.freedesktop.DBus.Introspectable.Introspect
<!DOCTYPE node PUBLIC "-//freedesktop//DTD D-BUS Object Introspection 1.0//EN"
"http://www.freedesktop.org/standards/dbus/1.0/introspect.dtd">
<node>
<interface name="org.ruby.SampleInterface">
<method name="hello">
<arg name="name" direction="in" type="s"/>
<arg name="name2" direction="in" type="s"/>
</method>
<method name="test_variant">
<arg name="stuff" direction="in" type="v"/>
</method>
<signal name="SomethingJustHappened">
<arg name="toto" type="s"/>
<arg name="tutu" type="u"/>
</signal>
</interface>
<interface name="org.ruby.AnotherInterface">
<method name="ThatsALongMethodNameIThink">
</method>
<method name="Reverse">
<arg name="instr" direction="in" type="s"/>
<arg name="outstr" direction="out" type="s"/>
</method>
</interface>
</node>

[mvidner]

• Cannot call methods: yes and no

As the error message is trying to tell you (Interface "" of ... does not exist), ruby-dbus requires method names to be qualified with the interface name. So this works:

$ qdbus org.ruby.service /org/ruby/MyInstance org.ruby.AnotherInterface.Reverse gateman
nametag

Also, ruby-dbus as the caller is able to fill in the interface from the introspection data (see PR #35), but as I've just realized on rereading the specification, that's a wrong place to fix it since the service should handlle it:

A method call message is required to have a MEMBER header field indicating the name of the method. Optionally, the message has an INTERFACE field giving the interface the method is a part of. In the absence of an INTERFACE field, if two interfaces on the same object have a method with the same name, it is undefined which of the two methods will be invoked. Implementations may also choose to return an error in this ambiguous case. However, if a method name is unique implementations must not require an interface field.

So I will fix that.

[mvidner]

Funny thing, the newest release of the DBus specification (0.23 from yesterday) no longer requires that a missing interface works. It is discussed in bug#68597. But I'll fix it anyway.