A method for establishing connection between a client and a server, the server supporting running at least a first instance and a second instance of a multi-user application, and the client supporting running at least a first application and a second application, wherein the first application supports interfacing the first instance, wherein the first application is connected to the first instance via a connection, and wherein a common data storage is connected to the server and the client, where the common data storage is accessible for the multi-user application and for the second application, the method comprising the steps of: - based on a request from a user of the client via an IP connection or on a request from any application running on the client, request the first instance to run, whereby the first application becomes a part of the first instance and the first instance is running on the server and on the client, the client having a client address, - the second application writing an address to the common data storage, wherein the writing makes the first instance aware of a request from the second application to connect to the written address, - said address being a communication port address of a communication port of the client or said address being an IP address of the second application, and the second application being unable to request connection to the first instance, - arranging the first instance to read from the common data storage, - applying a virtual server function within a client configuration to the second application and applying a virtual client function within a server configuration to the multi-user application, - the virtual server function of the second application waiting for a call from the server, - the virtual client function of the first instance reading the address from the common data storage, - the virtual client function of the first instance connecting to the virtual server function by calling the address, - said calling by the first instance thereby establishing connection between the second application running on the client and the first instance running on the server. - based on a request from a user of the client via an IP connection or on a request from any application running on the client, request the first instance to run, whereby the first application becomes a part of the first instance and the first instance is running on the server and on the client, the client having a client address, - the second application writing an address to the common data storage, wherein the writing makes the first instance aware of a request from the second application to connect to the written address, - said address being a communication port address of a communication port of the client or said address being an IP address of the second application, and the second application being unable to request connection to the first instance, - arranging the first instance to read from the common data storage, - applying a virtual server function within a client configuration to the second application and applying a virtual client function within a server configuration to the multi-user application, - the virtual server function of the second application waiting for a call from the server, - the virtual client function of the first instance reading the address from the common data storage, - the virtual client function of the first instance connecting to the virtual server function by calling the address, - said calling by the first instance thereby establishing connection between the second application running on the client and the first instance running on the server.