metapost schriftstile

[nameac]

Hallo Forum,

wie bekomme ich in dieser metapost Grafik den schriftstil
\renewcommand{\sfdefault}{lmss} hin?




input metaobj;
beginfig(1)
newEllipse.a(btex Server etex);
newEllipse.b(btex Client etex);
newBox.j(btex Rechenzeit etex);
newBox.k(btex Rechenzeit etex);
newBox.i(btex Step 1 etex);
newBox.c(btex Step 6 etex);
newBox.d(btex Step 5 etex);
newBox.e(btex Step 4 etex);
newBox.f(btex Step 3 etex);
newBox.g(btex Step 2 etex);
newBox.h(btex Step 1 etex);
a.c=origin;
a.c-j.c=(0cm,-2cm);
b.c-k.c=(0cm,-2cm);
b.c-a.c=(15cm,0cm);
i.c-a.c=(2.2cm,0cm);
c.c-i.c=(1.8cm,0cm);
d.c-c.c=(1.8cm,0cm);
e.c-d.c=(1.8cm,0cm);
f.c-e.c=(1.8cm,0cm);
g.c-f.c=(1.8cm,0cm);
h.c-g.c=(1.8cm,0cm);
ncline(a)(i)"doubleline(true)","arrows(draw)";
ncline(i)(c)"doubleline(true)","arrows(draw)";
ncline(c)(d)"doubleline(true)","arrows(draw)";
ncline(d)(e)"doubleline(true)","arrows(draw)";
ncline(e)(f)"doubleline(true)","arrows(draw)";
ncline(f)(g)"doubleline(true)","arrows(draw)";
ncline(g)(h)"doubleline(true)","arrows(draw)";
ncline(h)(b)"doubleline(true)","arrows(draw)";
ncline(a)(j)"arrows(drawarrow)";
ncline(b)(k)"arrows(drawarrow)";
nccurve(a)(b)"angleA(-20)","angleB(20)";
nccurve(a)(b)"angleA(20)","angleB(-20)","arrows(rdrawarrow)";
u=1.5pt;
labeloffset:=10pt;
label.urt (btex Übertragungszeit etex,(115u,22u));
label.urt (btex Übertragungszeit etex,(115u,-36u));
label.urt (btex Datenstrom etex,(115u,8u));
drawObj(a,b,c,d,e,f,g,h,i,j,k);
endfig;
end;