diff --git a/doc/diagrams/.gitignore b/doc/diagrams/.gitignore
new file mode 100644
index 0000000..0e77146
--- /dev/null
+++ b/doc/diagrams/.gitignore
@@ -0,0 +1,2 @@
+*.aux
+*.log
diff --git a/doc/diagrams/class-diagram.pdf b/doc/diagrams/class-diagram.pdf
new file mode 100644
index 0000000..9c89b0f
Binary files /dev/null and b/doc/diagrams/class-diagram.pdf differ
diff --git a/doc/diagrams/class-diagram.tex b/doc/diagrams/class-diagram.tex
new file mode 100644
index 0000000..828fbc2
--- /dev/null
+++ b/doc/diagrams/class-diagram.tex
@@ -0,0 +1,231 @@
+\documentclass[tikz]{standalone}
+
+\usepackage{etoolbox}
+
+\usetikzlibrary{
+    arrows.meta,
+    backgrounds,
+    calc,
+    fit,
+    positioning,
+    shadows,
+    shapes.multipart,
+}
+
+
+\begin{document}
+
+\definecolor{umlbgleft}{HTML}{F9D4A8}
+\definecolor{umlbgright}{HTML}{FEF8D2}
+\definecolor{umlifaceoutline}{HTML}{76907C}
+\definecolor{umlifacebgleft}{HTML}{C0D2C4}
+\definecolor{umlifacebgright}{HTML}{FAFCFB}
+\definecolor{umlificonoutline}{HTML}{76907C}
+\definecolor{umloutline}{HTML}{968255}
+\definecolor{umlpkgbgleft}{HTML}{D5DEFF}
+\definecolor{umlpkgbgright}{HTML}{F4F8FF}
+\definecolor{umlpkgoutline}{HTML}{8B90A9}
+\definecolor{umltypefg}{HTML}{606060}
+\definecolor{nonuml}{HTML}{606060}
+
+\newcommand\TallStrut{\vrule height 10pt depth 10pt width 0pt}
+
+\newcommand*\Param[2]{#1 : \textcolor{umltypefg}{#2}}
+\newcommand*\Op[3]{%
+    #1(\notblank{#2}{~}{}#2\notblank{#2}{~}{})%
+    \notblank{#3}{~:~\textcolor{umltypefg}{#3}}{}%
+}
+\newcommand\Ellipsis{~~~~\textcolor{nonuml}{[...]}}
+\newcommand*\Multiplicity[2]{~[#1..#2]}
+\newcommand\Any{*}
+\newcommand*\Stereo[1]{«#1»}
+
+\begin{tikzpicture}[
+    basic/.style={
+	draw=umloutline,
+	shading=axis,left color=umlbgleft,right color=umlbgright,
+	drop shadow,
+	font=\bfseries\large,
+    },
+    basictitle/.style={component,minimum height=4ex},
+    basicbox/.style={component,inner sep=1em},
+    basicsimple/.style={
+	basicbox,
+	text width=8em,text centered,minimum height=8ex,
+    },
+    classsimple/.style={basic,font=\bfseries\large,inner sep=1em},
+    classabstractsimple/.style={classsimple,font=\bfseries\itshape\large},
+    class/.style args={#1/#2}{
+	basic,rectangle split,rectangle split parts=2,
+	node contents={%
+	    \nodepart[align=center]{one}\TallStrut\raisebox{-.5ex}{\bfseries#1}%
+	    \nodepart{two}\texttt{#2}%
+	},
+    },
+    classabstract/.style args={#1/#2}{class={\textit{#1}/#2}},
+    iface/.style args={#1/#2}{
+	basic,
+	draw=umlifaceoutline,
+	shading=axis,left color=umlifacebgleft,
+	right color=umlifacebgright,
+	rectangle split,rectangle split parts=2,
+	node contents={%
+	    \nodepart[align=center]{one}{%
+		\bfseries\TallStrut\raisebox{-.5ex}{#1}%
+	    }%
+	    \nodepart{two}{\ttfamily#2}%
+	},
+    },
+    ifacesimple/.style={
+	basic,
+	draw=umloutline,
+	shading=axis,
+	left color=umlifacebgleft,right color=umlifacebgright,
+	inner sep=1em,
+    },
+    folder/.style={
+	basic,
+	draw=umlpkgoutline,
+	left color=umlpkgbgleft,right color=umlpkgbgright,
+	inner sep=1em,
+	append after command={
+	    \pgfextra{
+		\draw[
+		    umlpkgoutline,
+		    fill=umlpkgbgleft,
+		    drop shadow,
+		]
+		    ($(\tikzlastnode.north west)+(.5\pgflinewidth,-\pgflinewidth)$)
+		    rectangle
+		    ($(\tikzlastnode.north)+(-5em,+1.5em)$);
+	    }
+	},
+    },
+    ificon/.pic={
+	\draw[
+	    umlificonoutline,
+	    shading=axis,
+	    left color=umlifacebgleft,right color=umlifacebgright,
+	] (0,0) circle (8pt);
+    },
+    dep/.style={
+	->,dashed,thick,>={Straight Barb[length=.5em,width=.75em]}
+    },
+    impl/.style={dep,>={Triangle[open,length=.75em,width=.75em]}},
+    ext/.style={impl,solid},
+    assoc/.style={->,>={Straight Barb[length=.5em,width=.75em]}},
+    comp/.style={
+	assoc,
+	{Diamond[length=1em,width=.5em]}-{Straight Barb[length=.5em,width=.75em]}
+    },
+    rellab/.style={font=\ttfamily\large},
+]
+	\node (iregistry) [
+	    iface=RegistryInterface/{%
+		\Op{create}{%
+		    \Param{entity}{SerializableEntity}%
+		}{void} \\
+		\Op{read}{%
+		    \Param{entity}{SerializableEntity}%
+		}{void} \\
+		\Op{update}{%
+		    \Param{entity}{SerializableEntity}%
+		}{void} \\
+		\Op{delete}{%
+		    \Param{entity}{SerializableEntity}%
+		}{void} \\
+	    },text width=28em,
+	];
+	\pic at ($(iregistry.north east)+(-1.2em,-1.4em)$) {ificon};
+
+	\node[right=32em of iregistry.north,anchor=north] (ientity) [
+	    iface=SerializableEntityInterface/{%
+		\Op{getType}{}{String} \\
+		\Op{getKeyParts}{}{String\Multiplicity{1}{\Any}} \\
+		\Op{toBuffer}{}{byte\Multiplicity{1}{\Any}} \\
+		\Op{fromBuffer}{%
+		    \Param{buffer}{byte\Multiplicity{1}{\Any}}%
+		}{void} \\
+		\Op{toJson}{}{String} \\
+		\Op{fromJson}{\Param{json}{String}}{void} \\
+	    },text width=26em,
+	];
+	\pic at ($(ientity.north east)+(-1.2em,-1.4em)$) {ificon};
+
+	\node[below=of iregistry] (registry) [classsimple] {Registry};
+
+	\node[below=of registry] (ctxwreg) [
+	    class=ContextWithRegistry/{%
+		\Op{+getRegistry}{}{Registry}%
+	}];
+
+	\node[below=4em of ientity] (entitybase)
+	    [classabstractsimple] {SerializableEntityBase};
+	\node[below=of ctxwreg,xshift=12em] (mwbase)
+	    [classabstractsimple] {ChaincodeStubMiddlewareBase};
+
+	\node[below=15em of ctxwreg] (ctx)
+	    [class=Context/\Op{getStub}{}{ChaincodeStub},text width=17em];
+
+	\node[below=of ctx] (icontract)
+	    [ifacesimple,text width=16em,text centered]
+	    {ContractInterface};
+	\pic at ($(icontract.north east)+(-1.2em,-1.4em)$) {ificon};
+
+	\node[below=18em of entitybase] (istub) [
+	    iface=ChaincodeStub/{%
+		\Op{getState}{%
+		    \Param{key}{String}
+		}{byte\Multiplicity{0}{\Any}} \\
+		\Op{putState}{%
+		    \Param{key}{String},
+		    \Param{value}{byte\Multiplicity{0}{\Any}}%
+		}{void} \\
+		\Ellipsis
+	    },text width=32em,
+	];
+	\pic at ($(istub.north east)+(-1.2em,-1.4em)$) {ificon};
+
+	\coordinate[above=4em of iregistry] (fitcftsrg);
+	\begin{scope}[on background layer]
+		\node (pkgftsrg) [
+		    folder,
+		    fit=(fitcftsrg)(iregistry)(registry)(ctxwreg)(mwbase)(ientity)(entitybase)
+		] {};
+	\end{scope}
+	\node[font=\large\bfseries\ttfamily]
+	    at ($(pkgftsrg.north)+(0,-1em)$)
+	    {hu.bme.mit.ftsrg.chaincode.dataaccess};
+
+	\coordinate[above=2em of istub] (fitcfabric);
+	\begin{scope}[on background layer]
+		\node (pkgfabric) [
+		    folder,
+		    fit=(fitcfabric)(ctx)(icontract)(istub)
+		] {};
+	\end{scope}
+	\node[font=\large\bfseries\ttfamily]
+	    at ($(pkgfabric.north)+(0,-1em)$)
+	    {org.hyperledger.fabric};
+
+	\node[classsimple,left=15em of ctxwreg] (cc) {MyChaincode};
+
+	\draw[impl] (registry) -- (iregistry);
+	\draw[ext] (ctxwreg) -- (ctx);
+	\draw[comp] (ctxwreg)
+	    -- node[right,rellab,pos=.65] {-registry} (registry);
+	\draw[comp,transform canvas={yshift=-1em}] (ctx.east |- istub)
+	    -- node[below,rellab,pos=.7] {-stub} (istub);
+	\draw[dep] (iregistry) -- ++(-12em,-12em) -- (ctx);
+	\draw[dep] (iregistry.east |- ientity) -- (ientity);
+	\draw[impl] (mwbase) |- (istub);
+	\draw[assoc] (mwbase)
+	    -| node[right,rellab,pos=.95] {\#next} (istub);
+	\coordinate (chelper1) at ($(ctxwreg.south east)+(-2em,0)$);
+	\draw[dep] (chelper1) -- (chelper1 |- mwbase.north);
+	\draw[impl] (entitybase) -- (ientity);
+	\draw[dep] (cc) -- node[above,rellab,midway] {\Stereo{use}} (ctxwreg);
+	\draw[impl] (cc) |- (icontract);
+\end{tikzpicture}
+
+\end{document}
diff --git a/doc/diagrams/sequence-diagram.pdf b/doc/diagrams/sequence-diagram.pdf
new file mode 100644
index 0000000..5fbc48c
Binary files /dev/null and b/doc/diagrams/sequence-diagram.pdf differ
diff --git a/doc/diagrams/sequence-diagram.tex b/doc/diagrams/sequence-diagram.tex
new file mode 100644
index 0000000..b8cb5b4
--- /dev/null
+++ b/doc/diagrams/sequence-diagram.tex
@@ -0,0 +1,166 @@
+\documentclass[tikz]{standalone}
+
+\usetikzlibrary{
+    arrows.meta,
+    calc,
+    fit,
+    positioning,
+    shadows,
+    shapes.multipart,
+}
+
+
+\begin{document}
+
+\definecolor{umlactivationbg}{HTML}{C4E1D5}
+\definecolor{umlactorbgleft}{HTML}{CEE6DC}
+\definecolor{umlactorbgright}{HTML}{F6FEFB}
+\definecolor{umlactoroutline}{HTML}{000000}
+\definecolor{umlifacebgleft}{HTML}{C0D2C4}
+\definecolor{umlifacebgright}{HTML}{FAFCFB}
+\definecolor{umlificonoutline}{HTML}{76907C}
+
+\newcommand\TallStrut{\vrule height 10pt depth 10pt width 0pt}
+
+\newcommand*\Actor[2][]{#1~:~#2}
+\newcommand*\Stereo[1]{«#1»}
+
+\begin{tikzpicture}[
+    actor/.style={
+	draw=umlactoroutline,
+	shading=axis,
+	left color=umlactorbgleft,right color=umlactorbgright,
+	drop shadow,
+	font=\bfseries\Large,
+	node contents={\TallStrut\raisebox{-.5ex}{#1}},
+    minimum height=4em,
+    },
+    ificon/.pic={
+	\draw[
+	    umlificonoutline,
+	    shading=axis,
+	    left color=umlifacebgleft,right color=umlifacebgright,
+	] (0,0) circle (8pt);
+    },
+    activation/.style={
+	draw=black,fill=umlactivationbg,
+	inner xsep=.5em,inner ysep=0,
+	node contents={},
+    },
+    port/.style={
+	draw,fill=black,
+	minimum width=1em,minimum height=1em,
+	node contents={}
+    },
+    life/.style=loosely dashed,
+    longdashed/.style={dash pattern={on 8pt off 5pt}},
+    msg/.style={
+	-{Triangle[width=1em,length=1em]},
+	shorten >=.5em,shorten <=.5em,
+    },
+    reply/.style={
+	msg,longdashed,
+	-{Straight Barb[width=1em,length=1em]},
+    },
+    msgcreate/.style=reply,
+    msglab/.style={font=\ttfamily\Large},
+]
+
+	\node (cc) [actor={\Actor{MyChaincode}}];
+	\node (ctx)
+	    [actor={\Actor[ctx]{ContextWithRegistry}},right=of cc];
+	\node (ent)
+	    [actor={\Actor[ent]{Entity}},right=-6em of ctx,yshift=-12em];
+	\node (reg) [actor={\Actor[reg]{Registry}},right=8em of ctx];
+	\node (stub) [
+	    actor={\Actor[interceptor]{ChaincodeStub}},
+	    right=12em of reg,
+	    text width=25em,text centered,
+	];
+	\pic at ($(stub.north east)+(-1.4em,-1.8em)$) {ificon};
+	\node (fabstub) [
+	    actor={\Actor[fabricStub]{ChaincodeStub}},
+	    right=6em of stub,
+	    text width=24em,text centered,
+	];
+	\pic at ($(fabstub.north east)+(-1.4em,-1.8em)$) {ificon};
+
+	\coordinate (cbot) at ($(cc)+(0,-45em)$);
+	\foreach \a in {cc,ctx,ent,reg,stub,fabstub}
+	    \draw[life] (\a) -- (\a |- cbot);
+
+	\node (in) [port,left=16em of cc,yshift=-4em];
+
+	\coordinate (ccact1start) at (in.east -| cc);
+	\coordinate (ccact1end) at ($(cc.south)+(0,-42em)$);
+	\node (ccact1) [activation,fit=(ccact1start)(ccact1end)];
+	\draw[msg,shorten <=0em] (in)
+	    -- node[above,msglab] {invokeTx(ctx=ctx,parameters)}
+	    (in -| ccact1);
+
+	\coordinate (ctxact1start) at ($(ctx.south)+(0,-5em)$);
+	\coordinate (ctxact1end) at ($(ctxact1start)+(0,-2em)$);
+	\node (ctxact1) [activation,fit=(ctxact1start)(ctxact1end)];
+	\draw[msg] (ccact1 |- ctxact1start)
+	    -- node[above,msglab] {getRegistry()} (ctxact1start);
+	\draw[reply] (ctxact1end)
+	    -- node[above,msglab] {reg} (ctxact1end -| ccact1);
+
+	\draw[msgcreate] (ccact1 |- ent)
+	    -- node[above,msglab] {\Stereo{create}} (ent);
+
+	\coordinate (regact1start) at ($(reg.south)+(0,-15em)$);
+	\coordinate (regact1end) at ($(regact1start)+(0,-24em)$);
+	\node (regact1) [activation,fit=(regact1start)(regact1end)];
+	\draw[msg] (ccact1 |- regact1start)
+	    -- node[above,msglab] {create(ctx=ctx, entity=ent)}
+	    (regact1start);
+
+	\coordinate (ctxact2start) at ($(ctx.south)+(0,-18em)$);
+	\coordinate (ctxact2end) at ($(ctxact2start)+(0,-2em)$);
+	\node (ctxact1) [activation,fit=(ctxact2start)(ctxact2end)];
+	\draw[msg] (regact1 |- ctxact2start)
+	    -- node[above,msglab] {getStub()} (ctxact2start);
+	\draw[reply] (ctxact2end)
+	    -- node[above,msglab] {interceptor} (ctxact2end -| regact1);
+
+	\coordinate (entact1start) at ($(ent.south)+(0,-10em)$);
+	\coordinate (entact1end) at ($(entact1start)+(0,-2em)$);
+	\node (entact1) [activation,fit=(entact1start)(entact1end)];
+	\draw[msg] (regact1 |- entact1start)
+	    -- node[above,msglab] {getKeyParts()} (entact1start);
+	\draw[reply] (entact1end)
+	    -- node[above,msglab] {keyParts} (entact1end -| regact1);
+
+	\coordinate (entact2start) at ($(ent.south)+(0,-14em)$);
+	\coordinate (entact2end) at ($(entact2start)+(0,-2em)$);
+	\node (entact2) [activation,fit=(entact2start)(entact2end)];
+	\draw[msg] (regact1 |- entact2start)
+	    -- node[above,msglab] {toBuffer()} (entact2start);
+	\draw[reply] (entact2end)
+	    -- node[above,msglab] {buffer} (entact2end -| regact1);
+
+	\coordinate (stubact1start) at ($(stub.south)+(0,-30em)$);
+	\coordinate (stubact1end) at ($(stubact1start)+(0,-6em)$);
+	\node (stubact1) [activation,fit=(stubact1start)(stubact1end)];
+	\draw[msg] (regact1 |- stubact1start)
+	    -- node[above,msglab] {putState(key=keyParts,value=buffer)}
+	    (stubact1start);
+	\draw[reply] (stubact1end) -- (stubact1end -| regact1);
+
+	\coordinate (fabstubact1start) at ($(fabstub.south)+(0,-32em)$);
+	\coordinate (fabstubact1end) at ($(fabstubact1start)+(0,-2em)$);
+	\node (fabstubact1) [
+	    activation,fit=(fabstubact1start)(fabstubact1end),
+	];
+	\draw[msg] (stubact1 |- fabstubact1start)
+	    -- node[above,msglab] {putState(key=keyParts,value=buffer)}
+	    (fabstubact1start);
+	\draw[reply] (fabstubact1end) -- (fabstubact1end -| stubact1);
+
+	\draw[reply] (regact1end) -- (regact1end -| ccact1);
+
+	\draw[reply] (ccact1end) -- (ccact1end -| in) node[port,solid];
+\end{tikzpicture}
+
+\end{document}