An image forming system including an image forming apparatus (1-1w; 1-la) and a server, comprising: the image forming apparatus (1-1w; 1-la) includes a hardware resource including a scanner; a web browser; an operation part configured to display a screen of the web browser; and a web service server configured to receive an instruction from the server and conduct a scan process using the scanner based on the received instruction, said scan process being a scanning of the document, by using the scanner, to obtain image data to be stored in a memory of the image forming apparatus (1-1w, 1-la); and the server includes a web server, wherein the web service server is configured to receive the instruction from the web server; a web service client; a screen flow controlling part configured to receive an execution request sent from the web browser and send screen data to the image forming apparatus (1-1w; 1-la); a web service client configured to send the instruction to the image forming apparatus (1-1w; 1-la); and wherein the web browser sends a request for the screen data to the web server, receives the screen data which is sent from the web server in response to the request, displays the screen on the operation part based on the screen data for displaying the display, and sends the execution request to the web server in response to a user operation on the operation part; the web service client sends the instruction to the image forming apparatus (1-1w; 1-la) in response to the execution request sent from the web browser, and the web service server conducts the scan process in response to receiving the instruction. the image forming apparatus (1-1w; 1-la) includes a hardware resource including a scanner; a web browser; an operation part configured to display a screen of the web browser; and a web service server configured to receive an instruction from the server and conduct a scan process using the scanner based on the received instruction, said scan process being a scanning of the document, by using the scanner, to obtain image data to be stored in a memory of the image forming apparatus (1-1w, 1-la); and a hardware resource including a scanner; a web browser; an operation part configured to display a screen of the web browser; and a web service server configured to receive an instruction from the server and conduct a scan process using the scanner based on the received instruction, said scan process being a scanning of the document, by using the scanner, to obtain image data to be stored in a memory of the image forming apparatus (1-1w, 1-la); and the server includes a web server, wherein the web service server is configured to receive the instruction from the web server; a web service client; a screen flow controlling part configured to receive an execution request sent from the web browser and send screen data to the image forming apparatus (1-1w; 1-la); a web service client configured to send the instruction to the image forming apparatus (1-1w; 1-la); and a web server, wherein the web service server is configured to receive the instruction from the web server; a web service client; a screen flow controlling part configured to receive an execution request sent from the web browser and send screen data to the image forming apparatus (1-1w; 1-la); a web service client configured to send the instruction to the image forming apparatus (1-1w; 1-la); and wherein the web browser sends a request for the screen data to the web server, receives the screen data which is sent from the web server in response to the request, displays the screen on the operation part based on the screen data for displaying the display, and sends the execution request to the web server in response to a user operation on the operation part; the web service client sends the instruction to the image forming apparatus (1-1w; 1-la) in response to the execution request sent from the web browser, and the web service server conducts the scan process in response to receiving the instruction. the web browser sends a request for the screen data to the web server, receives the screen data which is sent from the web server in response to the request, displays the screen on the operation part based on the screen data for displaying the display, and sends the execution request to the web server in response to a user operation on the operation part; the web service client sends the instruction to the image forming apparatus (1-1w; 1-la) in response to the execution request sent from the web browser, and the web service server conducts the scan process in response to receiving the instruction.