A method for use in a publish-subscribe messaging system comprising a broker, a subscriber, and a publisher communicating messages over a communication network, the method comprising: the broker receiving from the subscriber a first subscribe message (300, 400) comprising a first topic identifier; the broker receiving from the publisher a first publication message (301, 401) comprising a second topic identifier and a complete object, wherein the complete object comprises a set of information comprising: information corresponding to a first part of the complete object and information corresponding to a second part of the complete object that is different than the first part of the complete object, wherein the second topic identifier matches the first topic identifier; the broker sending to the subscriber a second publication message (302, 402) comprising the complete object; the broker, after receiving the first publication message (301, 401), receiving from the publisher a third publication message (306, 405) comprising the second topic identifier and a partial object comprising information corresponding to the first part of the complete object, but the partial object not including any information corresponding to the second part of the complete obj ect; after receiving the third publication message (360, 405), the broker receiving from the subscriber a second subscribe message (307, 406) comprising the first topic identifier; characterized in that, as a result of receiving the second subscribe message (307, 406), the broker determining whether to send to the subscriber said partial object, wherein determining whether to send to the subscriber said partial object comprises the broker determining whether the subscriber has previously received said partial object; and after determining that the subscriber has not previously received said partial object, the broker sending to the subscriber a fourth publication message (308, 407) comprising said partial object. the broker receiving from the subscriber a first subscribe message (300, 400) comprising a first topic identifier; the broker receiving from the publisher a first publication message (301, 401) comprising a second topic identifier and a complete object, wherein the complete object comprises a set of information comprising: information corresponding to a first part of the complete object and information corresponding to a second part of the complete object that is different than the first part of the complete object, wherein the second topic identifier matches the first topic identifier; the broker sending to the subscriber a second publication message (302, 402) comprising the complete object; the broker, after receiving the first publication message (301, 401), receiving from the publisher a third publication message (306, 405) comprising the second topic identifier and a partial object comprising information corresponding to the first part of the complete object, but the partial object not including any information corresponding to the second part of the complete obj ect; after receiving the third publication message (360, 405), the broker receiving from the subscriber a second subscribe message (307, 406) comprising the first topic identifier; characterized in that, as a result of receiving the second subscribe message (307, 406), the broker determining whether to send to the subscriber said partial object, wherein determining whether to send to the subscriber said partial object comprises the broker determining whether the subscriber has previously received said partial object; and after determining that the subscriber has not previously received said partial object, the broker sending to the subscriber a fourth publication message (308, 407) comprising said partial object.