diff --git a/doc/lua-api/_static/channel.fig b/doc/lua-api/_static/channel.fig
new file mode 100644
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+#FIG 3.2  Produced by xfig version 3.2.5b
+Landscape
+Center
+Metric
+A4      
+100.00
+Single
+-2
+1200 2
+1 1 0 1 0 7 50 -1 -1 0.000 1 0.0000 4500 1620 1260 585 4500 1620 5760 2205
+2 3 0 1 0 7 50 -1 -1 0.000 0 0 -1 0 0 9
+	 1170 1350 1170 1890 2790 1890 2790 2070 3240 1620 2790 1170
+	 2790 1350 1170 1350 1170 1350
+2 3 0 1 0 7 50 -1 -1 0.000 0 0 -1 0 0 9
+	 5760 1350 5760 1890 7380 1890 7380 2070 7830 1620 7380 1170
+	 7380 1350 5760 1350 5760 1350
+2 1 1 1 0 7 50 -1 -1 1.000 0 0 -1 1 0 2
+	5 1 1.00 60.00 120.00
+	 6210 540 6210 1440
+2 1 1 1 0 7 50 -1 -1 1.000 0 0 -1 1 0 2
+	5 1 1.00 60.00 120.00
+	 6210 2340 6210 1800
+2 1 1 1 0 7 50 -1 -1 1.000 0 0 -1 1 0 2
+	5 1 1.00 60.00 120.00
+	 1350 2520 1350 1800
+2 1 1 1 0 7 50 -1 -1 1.000 0 0 -1 1 0 2
+	5 1 1.00 60.00 120.00
+	 1350 360 1350 1440
+3 0 1 1 0 7 50 -1 -1 1.000 0 0 1 5
+	5 1 1.00 60.00 120.00
+	 2970 1665 3105 1125 3330 900 3600 765 3915 720
+	 0.000 1.000 1.000 1.000 0.000
+3 0 1 1 0 7 50 -1 -1 1.000 0 0 1 5
+	5 1 1.00 60.00 120.00
+	 6030 1665 5895 1125 5670 900 5400 765 5040 720
+	 0.000 1.000 1.000 1.000 0.000
+4 2 0 50 -1 16 12 0.0000 4 195 750 1080 1665 producer\001
+4 1 0 50 -1 16 12 0.0000 4 195 1785 4500 1575 HAProxy processing\001
+4 1 0 50 -1 16 12 0.0000 4 195 1260 4500 1815 (including Lua)\001
+4 0 0 50 -1 16 12 0.0000 4 105 855 7920 1665 consumer\001
+4 0 0 50 -1 12 12 0.0000 4 150 600 1440 2205 set()\001
+4 0 0 50 -1 12 12 0.0000 4 165 960 1440 2400 append()\001
+4 0 0 50 -1 16 12 0.0000 4 150 1260 1260 2700 write functions\001
+4 0 0 50 -1 16 12 0.0000 4 150 1230 1260 315 read functions\001
+4 0 0 50 -1 12 12 0.0000 4 165 600 1440 540 dup()\001
+4 0 0 50 -1 12 12 0.0000 4 165 600 1440 735 get()\001
+4 0 0 50 -1 12 12 0.0000 4 165 1200 1440 930 get_line()\001
+4 0 0 50 -1 12 12 0.0000 4 165 1440 1440 1125 get_in_len()\001
+4 1 0 50 -1 12 12 0.0000 4 150 1080 4500 765 forward()\001
+4 0 0 50 -1 16 12 0.0000 4 150 1260 6120 495 write functions\001
+4 0 0 50 -1 12 12 0.0000 4 150 720 6300 1110 send()\001
+4 0 0 50 -1 12 12 0.0000 4 165 1560 6255 2205 get_out_len()\001
+4 0 0 50 -1 16 12 0.0000 4 150 1230 6120 2520 read functions\001
+4 1 0 50 -1 16 12 0.0000 4 150 1650 4500 540 both side functions\001