diff --git a/server/src/domain/handler.rs b/server/src/domain/handler.rs
index 9eb0d52..ef43e93 100644
--- a/server/src/domain/handler.rs
+++ b/server/src/domain/handler.rs
@@ -1,223 +1,13 @@
-use super::error::*;
+use super::{
+    error::Result,
+    types::{
+        Group, GroupDetails, GroupId, JpegPhoto, User, UserAndGroups, UserColumn, UserId, Uuid,
+    },
+};
 use async_trait::async_trait;
 use serde::{Deserialize, Serialize};
 use std::collections::HashSet;
 
-pub use super::model::{GroupColumn, UserColumn};
-
-#[derive(PartialEq, Hash, Eq, Clone, Debug, Default, Serialize, Deserialize)]
-#[serde(try_from = "&str")]
-pub struct Uuid(String);
-
-impl Uuid {
-    pub fn from_name_and_date(name: &str, creation_date: &chrono::DateTime<chrono::Utc>) -> Self {
-        Uuid(
-            uuid::Uuid::new_v3(
-                &uuid::Uuid::NAMESPACE_X500,
-                &[name.as_bytes(), creation_date.to_rfc3339().as_bytes()].concat(),
-            )
-            .to_string(),
-        )
-    }
-
-    pub fn as_str(&self) -> &str {
-        &self.0
-    }
-
-    pub fn into_string(self) -> String {
-        self.0
-    }
-}
-
-impl<'a> std::convert::TryFrom<&'a str> for Uuid {
-    type Error = anyhow::Error;
-    fn try_from(s: &'a str) -> anyhow::Result<Self> {
-        Ok(Uuid(uuid::Uuid::parse_str(s)?.to_string()))
-    }
-}
-
-impl std::string::ToString for Uuid {
-    fn to_string(&self) -> String {
-        self.0.clone()
-    }
-}
-
-impl sea_orm::TryGetable for Uuid {
-    fn try_get(
-        res: &sea_orm::QueryResult,
-        pre: &str,
-        col: &str,
-    ) -> std::result::Result<Self, sea_orm::TryGetError> {
-        Ok(Uuid(String::try_get(res, pre, col)?))
-    }
-}
-
-#[cfg(test)]
-#[macro_export]
-macro_rules! uuid {
-    ($s:literal) => {
-        <$crate::domain::handler::Uuid as std::convert::TryFrom<_>>::try_from($s).unwrap()
-    };
-}
-
-#[derive(PartialEq, Eq, Clone, Debug, Default, Serialize, Deserialize)]
-#[serde(from = "String")]
-pub struct UserId(String);
-
-impl UserId {
-    pub fn new(user_id: &str) -> Self {
-        Self(user_id.to_lowercase())
-    }
-
-    pub fn as_str(&self) -> &str {
-        self.0.as_str()
-    }
-
-    pub fn into_string(self) -> String {
-        self.0
-    }
-}
-
-impl std::fmt::Display for UserId {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
-        write!(f, "{}", self.0)
-    }
-}
-
-impl From<String> for UserId {
-    fn from(s: String) -> Self {
-        Self::new(&s)
-    }
-}
-
-#[derive(PartialEq, Eq, Clone, Debug, Serialize, Deserialize)]
-pub struct JpegPhoto(#[serde(with = "serde_bytes")] Vec<u8>);
-
-impl JpegPhoto {
-    pub fn null() -> Self {
-        Self(vec![])
-    }
-}
-
-impl From<JpegPhoto> for sea_orm::Value {
-    fn from(photo: JpegPhoto) -> Self {
-        photo.0.into()
-    }
-}
-
-impl From<&JpegPhoto> for sea_orm::Value {
-    fn from(photo: &JpegPhoto) -> Self {
-        photo.0.as_slice().into()
-    }
-}
-
-impl TryFrom<&[u8]> for JpegPhoto {
-    type Error = anyhow::Error;
-    fn try_from(bytes: &[u8]) -> anyhow::Result<Self> {
-        if bytes.is_empty() {
-            return Ok(JpegPhoto::null());
-        }
-        // Confirm that it's a valid Jpeg, then store only the bytes.
-        image::io::Reader::with_format(std::io::Cursor::new(bytes), image::ImageFormat::Jpeg)
-            .decode()?;
-        Ok(JpegPhoto(bytes.to_vec()))
-    }
-}
-
-impl TryFrom<Vec<u8>> for JpegPhoto {
-    type Error = anyhow::Error;
-    fn try_from(bytes: Vec<u8>) -> anyhow::Result<Self> {
-        if bytes.is_empty() {
-            return Ok(JpegPhoto::null());
-        }
-        // Confirm that it's a valid Jpeg, then store only the bytes.
-        image::io::Reader::with_format(
-            std::io::Cursor::new(bytes.as_slice()),
-            image::ImageFormat::Jpeg,
-        )
-        .decode()?;
-        Ok(JpegPhoto(bytes))
-    }
-}
-
-impl TryFrom<String> for JpegPhoto {
-    type Error = anyhow::Error;
-    fn try_from(string: String) -> anyhow::Result<Self> {
-        // The String format is in base64.
-        Self::try_from(base64::decode(string.as_str())?)
-    }
-}
-
-impl From<&JpegPhoto> for String {
-    fn from(val: &JpegPhoto) -> Self {
-        base64::encode(&val.0)
-    }
-}
-
-impl JpegPhoto {
-    pub fn into_bytes(self) -> Vec<u8> {
-        self.0
-    }
-
-    #[cfg(test)]
-    pub fn for_tests() -> Self {
-        use image::{ImageOutputFormat, Rgb, RgbImage};
-        let img = RgbImage::from_fn(32, 32, |x, y| {
-            if (x + y) % 2 == 0 {
-                Rgb([0, 0, 0])
-            } else {
-                Rgb([255, 255, 255])
-            }
-        });
-        let mut bytes: Vec<u8> = Vec::new();
-        img.write_to(
-            &mut std::io::Cursor::new(&mut bytes),
-            ImageOutputFormat::Jpeg(0),
-        )
-        .unwrap();
-        Self(bytes)
-    }
-}
-
-#[derive(PartialEq, Eq, Debug, Clone, Serialize, Deserialize, sea_orm::FromQueryResult)]
-pub struct User {
-    pub user_id: UserId,
-    pub email: String,
-    pub display_name: Option<String>,
-    pub first_name: Option<String>,
-    pub last_name: Option<String>,
-    pub avatar: Option<JpegPhoto>,
-    pub creation_date: chrono::DateTime<chrono::Utc>,
-    pub uuid: Uuid,
-}
-
-#[cfg(test)]
-impl Default for User {
-    fn default() -> Self {
-        use chrono::TimeZone;
-        let epoch = chrono::Utc.timestamp_opt(0, 0).unwrap();
-        User {
-            user_id: UserId::default(),
-            email: String::new(),
-            display_name: None,
-            first_name: None,
-            last_name: None,
-            avatar: None,
-            creation_date: epoch,
-            uuid: Uuid::from_name_and_date("", &epoch),
-        }
-    }
-}
-
-#[derive(PartialEq, Eq, Debug, Serialize, Deserialize)]
-pub struct Group {
-    pub id: GroupId,
-    pub display_name: String,
-    pub creation_date: chrono::DateTime<chrono::Utc>,
-    pub uuid: Uuid,
-    pub users: Vec<UserId>,
-}
-
 #[derive(PartialEq, Eq, Debug, Serialize, Deserialize, Clone)]
 pub struct BindRequest {
     pub name: UserId,
@@ -282,23 +72,6 @@ pub trait LoginHandler: Clone + Send {
     async fn bind(&self, request: BindRequest) -> Result<()>;
 }
 
-#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash, Serialize, Deserialize)]
-pub struct GroupId(pub i32);
-
-#[derive(Debug, Clone, PartialEq, Eq, Hash, Serialize, Deserialize, sea_orm::FromQueryResult)]
-pub struct GroupDetails {
-    pub group_id: GroupId,
-    pub display_name: String,
-    pub creation_date: chrono::DateTime<chrono::Utc>,
-    pub uuid: Uuid,
-}
-
-#[derive(Debug, Clone, PartialEq, Eq)]
-pub struct UserAndGroups {
-    pub user: User,
-    pub groups: Option<Vec<GroupDetails>>,
-}
-
 #[async_trait]
 pub trait GroupBackendHandler {
     async fn list_groups(&self, filters: Option<GroupRequestFilter>) -> Result<Vec<Group>>;
diff --git a/server/src/domain/ldap/group.rs b/server/src/domain/ldap/group.rs
index cd4759a..2ab5b64 100644
--- a/server/src/domain/ldap/group.rs
+++ b/server/src/domain/ldap/group.rs
@@ -4,8 +4,9 @@ use ldap3_proto::{
 use tracing::{debug, info, instrument, warn};
 
 use crate::domain::{
-    handler::{BackendHandler, Group, GroupColumn, GroupRequestFilter, UserId, Uuid},
+    handler::{BackendHandler, GroupRequestFilter},
     ldap::error::LdapError,
+    types::{Group, GroupColumn, UserId, Uuid},
 };
 
 use super::{
diff --git a/server/src/domain/ldap/user.rs b/server/src/domain/ldap/user.rs
index 35919e1..08f9853 100644
--- a/server/src/domain/ldap/user.rs
+++ b/server/src/domain/ldap/user.rs
@@ -4,8 +4,9 @@ use ldap3_proto::{
 use tracing::{debug, info, instrument, warn};
 
 use crate::domain::{
-    handler::{BackendHandler, GroupDetails, User, UserColumn, UserId, UserRequestFilter},
+    handler::{BackendHandler, UserRequestFilter},
     ldap::{error::LdapError, utils::expand_attribute_wildcards},
+    types::{GroupDetails, User, UserColumn, UserId},
 };
 
 use super::{
diff --git a/server/src/domain/ldap/utils.rs b/server/src/domain/ldap/utils.rs
index b1de711..e2cbec4 100644
--- a/server/src/domain/ldap/utils.rs
+++ b/server/src/domain/ldap/utils.rs
@@ -2,9 +2,10 @@ use itertools::Itertools;
 use ldap3_proto::LdapResultCode;
 use tracing::{debug, instrument, warn};
 
-use crate::domain::handler::{GroupColumn, UserColumn, UserId};
-
-use super::error::{LdapError, LdapResult};
+use crate::domain::{
+    ldap::error::{LdapError, LdapResult},
+    types::{GroupColumn, UserColumn, UserId},
+};
 
 fn make_dn_pair<I>(mut iter: I) -> LdapResult<(String, String)>
 where
diff --git a/server/src/domain/mod.rs b/server/src/domain/mod.rs
index 8047331..c122cf8 100644
--- a/server/src/domain/mod.rs
+++ b/server/src/domain/mod.rs
@@ -9,3 +9,4 @@ pub mod sql_migrations;
 pub mod sql_opaque_handler;
 pub mod sql_tables;
 pub mod sql_user_backend_handler;
+pub mod types;
diff --git a/server/src/domain/model/groups.rs b/server/src/domain/model/groups.rs
index eb5342e..748a61e 100644
--- a/server/src/domain/model/groups.rs
+++ b/server/src/domain/model/groups.rs
@@ -3,7 +3,7 @@
 use sea_orm::entity::prelude::*;
 use serde::{Deserialize, Serialize};
 
-use crate::domain::handler::{GroupId, Uuid};
+use crate::domain::types::{GroupId, Uuid};
 
 #[derive(Clone, Debug, PartialEq, DeriveEntityModel, Eq, Serialize, Deserialize)]
 #[sea_orm(table_name = "groups")]
@@ -15,29 +15,6 @@ pub struct Model {
     pub uuid: Uuid,
 }
 
-impl From<Model> for crate::domain::handler::Group {
-    fn from(group: Model) -> Self {
-        Self {
-            id: group.group_id,
-            display_name: group.display_name,
-            creation_date: group.creation_date,
-            uuid: group.uuid,
-            users: vec![],
-        }
-    }
-}
-
-impl From<Model> for crate::domain::handler::GroupDetails {
-    fn from(group: Model) -> Self {
-        Self {
-            group_id: group.group_id,
-            display_name: group.display_name,
-            creation_date: group.creation_date,
-            uuid: group.uuid,
-        }
-    }
-}
-
 #[derive(Copy, Clone, Debug, EnumIter, DeriveRelation)]
 pub enum Relation {
     #[sea_orm(has_many = "super::memberships::Entity")]
@@ -51,3 +28,26 @@ impl Related<super::memberships::Entity> for Entity {
 }
 
 impl ActiveModelBehavior for ActiveModel {}
+
+impl From<Model> for crate::domain::types::Group {
+    fn from(group: Model) -> Self {
+        Self {
+            id: group.group_id,
+            display_name: group.display_name,
+            creation_date: group.creation_date,
+            uuid: group.uuid,
+            users: vec![],
+        }
+    }
+}
+
+impl From<Model> for crate::domain::types::GroupDetails {
+    fn from(group: Model) -> Self {
+        Self {
+            group_id: group.group_id,
+            display_name: group.display_name,
+            creation_date: group.creation_date,
+            uuid: group.uuid,
+        }
+    }
+}
diff --git a/server/src/domain/model/jwt_refresh_storage.rs b/server/src/domain/model/jwt_refresh_storage.rs
index 16b35ef..d7753ff 100644
--- a/server/src/domain/model/jwt_refresh_storage.rs
+++ b/server/src/domain/model/jwt_refresh_storage.rs
@@ -3,7 +3,7 @@
 use sea_orm::entity::prelude::*;
 use serde::{Deserialize, Serialize};
 
-use crate::domain::handler::UserId;
+use crate::domain::types::UserId;
 
 #[derive(Clone, Debug, PartialEq, DeriveEntityModel, Eq, Serialize, Deserialize)]
 #[sea_orm(table_name = "jwt_refresh_storage")]
diff --git a/server/src/domain/model/jwt_storage.rs b/server/src/domain/model/jwt_storage.rs
index 0df0144..6fc6a4e 100644
--- a/server/src/domain/model/jwt_storage.rs
+++ b/server/src/domain/model/jwt_storage.rs
@@ -3,7 +3,7 @@
 use sea_orm::entity::prelude::*;
 use serde::{Deserialize, Serialize};
 
-use crate::domain::handler::UserId;
+use crate::domain::types::UserId;
 
 #[derive(Clone, Debug, PartialEq, DeriveEntityModel, Eq, Serialize, Deserialize)]
 #[sea_orm(table_name = "jwt_storage")]
diff --git a/server/src/domain/model/memberships.rs b/server/src/domain/model/memberships.rs
index aff6b3e..a1fb5a7 100644
--- a/server/src/domain/model/memberships.rs
+++ b/server/src/domain/model/memberships.rs
@@ -3,7 +3,7 @@
 use sea_orm::entity::prelude::*;
 use serde::{Deserialize, Serialize};
 
-use crate::domain::handler::{GroupId, UserId};
+use crate::domain::types::{GroupId, UserId};
 
 #[derive(Clone, Debug, PartialEq, DeriveEntityModel, Eq, Serialize, Deserialize)]
 #[sea_orm(table_name = "memberships")]
diff --git a/server/src/domain/model/password_reset_tokens.rs b/server/src/domain/model/password_reset_tokens.rs
index 03ee09b..54b1bea 100644
--- a/server/src/domain/model/password_reset_tokens.rs
+++ b/server/src/domain/model/password_reset_tokens.rs
@@ -3,7 +3,7 @@
 use sea_orm::entity::prelude::*;
 use serde::{Deserialize, Serialize};
 
-use crate::domain::handler::UserId;
+use crate::domain::types::UserId;
 
 #[derive(Clone, Debug, PartialEq, DeriveEntityModel, Eq, Serialize, Deserialize)]
 #[sea_orm(table_name = "password_reset_tokens")]
diff --git a/server/src/domain/model/users.rs b/server/src/domain/model/users.rs
index 6421084..a9f1b02 100644
--- a/server/src/domain/model/users.rs
+++ b/server/src/domain/model/users.rs
@@ -3,7 +3,7 @@
 use sea_orm::entity::prelude::*;
 use serde::{Deserialize, Serialize};
 
-use crate::domain::handler::{JpegPhoto, UserId, Uuid};
+use crate::domain::types::{JpegPhoto, UserId, Uuid};
 
 #[derive(Copy, Clone, Default, Debug, DeriveEntity)]
 pub struct Entity;
@@ -118,7 +118,7 @@ impl Related<super::password_reset_tokens::Entity> for Entity {
 
 impl ActiveModelBehavior for ActiveModel {}
 
-impl From<Model> for crate::domain::handler::User {
+impl From<Model> for crate::domain::types::User {
     fn from(user: Model) -> Self {
         Self {
             user_id: user.user_id,
diff --git a/server/src/domain/opaque_handler.rs b/server/src/domain/opaque_handler.rs
index 7e78299..d5f71dd 100644
--- a/server/src/domain/opaque_handler.rs
+++ b/server/src/domain/opaque_handler.rs
@@ -1,4 +1,4 @@
-use crate::domain::{error::*, handler::UserId};
+use crate::domain::{error::Result, types::UserId};
 use async_trait::async_trait;
 
 pub use lldap_auth::{login, registration};
diff --git a/server/src/domain/sql_backend_handler.rs b/server/src/domain/sql_backend_handler.rs
index 7640510..86181f7 100644
--- a/server/src/domain/sql_backend_handler.rs
+++ b/server/src/domain/sql_backend_handler.rs
@@ -1,4 +1,4 @@
-use super::{handler::*, sql_tables::*};
+use super::{handler::BackendHandler, sql_tables::DbConnection};
 use crate::infra::configuration::Configuration;
 use async_trait::async_trait;
 
@@ -20,8 +20,16 @@ impl BackendHandler for SqlBackendHandler {}
 #[cfg(test)]
 pub mod tests {
     use super::*;
-    use crate::domain::sql_tables::init_table;
-    use crate::infra::configuration::ConfigurationBuilder;
+    use crate::{
+        domain::{
+            handler::{
+                CreateUserRequest, GroupBackendHandler, UserBackendHandler, UserRequestFilter,
+            },
+            sql_tables::init_table,
+            types::{GroupId, UserId},
+        },
+        infra::configuration::ConfigurationBuilder,
+    };
     use lldap_auth::{opaque, registration};
     use sea_orm::Database;
 
diff --git a/server/src/domain/sql_group_backend_handler.rs b/server/src/domain/sql_group_backend_handler.rs
index 44e5863..f3cf463 100644
--- a/server/src/domain/sql_group_backend_handler.rs
+++ b/server/src/domain/sql_group_backend_handler.rs
@@ -1,12 +1,9 @@
-use crate::domain::handler::Uuid;
-
-use super::{
+use crate::domain::{
     error::{DomainError, Result},
-    handler::{
-        Group, GroupBackendHandler, GroupDetails, GroupId, GroupRequestFilter, UpdateGroupRequest,
-    },
+    handler::{GroupBackendHandler, GroupRequestFilter, UpdateGroupRequest},
     model::{self, GroupColumn, MembershipColumn},
     sql_backend_handler::SqlBackendHandler,
+    types::{Group, GroupDetails, GroupId, Uuid},
 };
 use async_trait::async_trait;
 use sea_orm::{
@@ -155,7 +152,7 @@ impl GroupBackendHandler for SqlBackendHandler {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::domain::{handler::UserId, sql_backend_handler::tests::*};
+    use crate::domain::{sql_backend_handler::tests::*, types::UserId};
 
     async fn get_group_ids(
         handler: &SqlBackendHandler,
diff --git a/server/src/domain/sql_migrations.rs b/server/src/domain/sql_migrations.rs
index 7d252b8..62d9e59 100644
--- a/server/src/domain/sql_migrations.rs
+++ b/server/src/domain/sql_migrations.rs
@@ -1,6 +1,6 @@
-use super::{
-    handler::{GroupId, UserId, Uuid},
+use crate::domain::{
     sql_tables::{DbConnection, SchemaVersion},
+    types::{GroupId, UserId, Uuid},
 };
 use sea_orm::{ConnectionTrait, FromQueryResult, Statement};
 use sea_query::{ColumnDef, Expr, ForeignKey, ForeignKeyAction, Iden, Query, Table, Value};
diff --git a/server/src/domain/sql_opaque_handler.rs b/server/src/domain/sql_opaque_handler.rs
index dda433d..9fd7e66 100644
--- a/server/src/domain/sql_opaque_handler.rs
+++ b/server/src/domain/sql_opaque_handler.rs
@@ -1,9 +1,10 @@
 use super::{
     error::{DomainError, Result},
-    handler::{BindRequest, LoginHandler, UserId},
+    handler::{BindRequest, LoginHandler},
     model::{self, UserColumn},
     opaque_handler::{login, registration, OpaqueHandler},
     sql_backend_handler::SqlBackendHandler,
+    types::UserId,
 };
 use async_trait::async_trait;
 use lldap_auth::opaque;
diff --git a/server/src/domain/sql_tables.rs b/server/src/domain/sql_tables.rs
index 1e09ae3..af5615a 100644
--- a/server/src/domain/sql_tables.rs
+++ b/server/src/domain/sql_tables.rs
@@ -1,8 +1,5 @@
-use super::{
-    handler::{GroupId, JpegPhoto, UserId, Uuid},
-    sql_migrations::{get_schema_version, migrate_from_version, upgrade_to_v1},
-};
-use sea_orm::{DbErr, Value};
+use super::sql_migrations::{get_schema_version, migrate_from_version, upgrade_to_v1};
+use sea_orm::Value;
 
 pub type DbConnection = sea_orm::DatabaseConnection;
 
@@ -19,181 +16,6 @@ impl sea_orm::TryGetable for SchemaVersion {
     }
 }
 
-impl From<GroupId> for sea_orm::Value {
-    fn from(group_id: GroupId) -> Self {
-        group_id.0.into()
-    }
-}
-
-impl sea_orm::TryGetable for GroupId {
-    fn try_get(
-        res: &sea_orm::QueryResult,
-        pre: &str,
-        col: &str,
-    ) -> Result<Self, sea_orm::TryGetError> {
-        Ok(GroupId(i32::try_get(res, pre, col)?))
-    }
-}
-
-impl sea_orm::sea_query::value::ValueType for GroupId {
-    fn try_from(v: sea_orm::Value) -> Result<Self, sea_orm::sea_query::ValueTypeErr> {
-        Ok(GroupId(<i32 as sea_orm::sea_query::ValueType>::try_from(
-            v,
-        )?))
-    }
-
-    fn type_name() -> String {
-        "GroupId".to_owned()
-    }
-
-    fn array_type() -> sea_orm::sea_query::ArrayType {
-        sea_orm::sea_query::ArrayType::Int
-    }
-
-    fn column_type() -> sea_orm::sea_query::ColumnType {
-        sea_orm::sea_query::ColumnType::Integer(None)
-    }
-}
-
-impl sea_orm::TryFromU64 for GroupId {
-    fn try_from_u64(n: u64) -> Result<Self, sea_orm::DbErr> {
-        Ok(GroupId(i32::try_from_u64(n)?))
-    }
-}
-
-impl From<UserId> for sea_orm::Value {
-    fn from(user_id: UserId) -> Self {
-        user_id.into_string().into()
-    }
-}
-
-impl From<&UserId> for sea_orm::Value {
-    fn from(user_id: &UserId) -> Self {
-        user_id.as_str().into()
-    }
-}
-
-impl sea_orm::TryGetable for UserId {
-    fn try_get(
-        res: &sea_orm::QueryResult,
-        pre: &str,
-        col: &str,
-    ) -> Result<Self, sea_orm::TryGetError> {
-        Ok(UserId::new(&String::try_get(res, pre, col)?))
-    }
-}
-
-impl sea_orm::TryFromU64 for UserId {
-    fn try_from_u64(_n: u64) -> Result<Self, sea_orm::DbErr> {
-        Err(sea_orm::DbErr::ConvertFromU64(
-            "UserId cannot be constructed from u64",
-        ))
-    }
-}
-
-impl sea_orm::sea_query::value::ValueType for UserId {
-    fn try_from(v: sea_orm::Value) -> Result<Self, sea_orm::sea_query::ValueTypeErr> {
-        Ok(UserId::new(
-            <String as sea_orm::sea_query::ValueType>::try_from(v)?.as_str(),
-        ))
-    }
-
-    fn type_name() -> String {
-        "UserId".to_owned()
-    }
-
-    fn array_type() -> sea_orm::sea_query::ArrayType {
-        sea_orm::sea_query::ArrayType::String
-    }
-
-    fn column_type() -> sea_orm::sea_query::ColumnType {
-        sea_orm::sea_query::ColumnType::String(Some(255))
-    }
-}
-
-impl From<Uuid> for sea_query::Value {
-    fn from(uuid: Uuid) -> Self {
-        uuid.as_str().into()
-    }
-}
-
-impl From<&Uuid> for sea_query::Value {
-    fn from(uuid: &Uuid) -> Self {
-        uuid.as_str().into()
-    }
-}
-
-impl sea_orm::TryGetable for JpegPhoto {
-    fn try_get(
-        res: &sea_orm::QueryResult,
-        pre: &str,
-        col: &str,
-    ) -> Result<Self, sea_orm::TryGetError> {
-        <JpegPhoto as std::convert::TryFrom<Vec<_>>>::try_from(Vec::<u8>::try_get(res, pre, col)?)
-            .map_err(|e| {
-                sea_orm::TryGetError::DbErr(DbErr::TryIntoErr {
-                    from: "[u8]",
-                    into: "JpegPhoto",
-                    source: e.into(),
-                })
-            })
-    }
-}
-
-impl sea_orm::sea_query::value::ValueType for JpegPhoto {
-    fn try_from(v: sea_orm::Value) -> Result<Self, sea_orm::sea_query::ValueTypeErr> {
-        <JpegPhoto as std::convert::TryFrom<_>>::try_from(
-            <Vec<u8> as sea_orm::sea_query::ValueType>::try_from(v)?.as_slice(),
-        )
-        .map_err(|_| sea_orm::sea_query::ValueTypeErr {})
-    }
-
-    fn type_name() -> String {
-        "JpegPhoto".to_owned()
-    }
-
-    fn array_type() -> sea_orm::sea_query::ArrayType {
-        sea_orm::sea_query::ArrayType::Bytes
-    }
-
-    fn column_type() -> sea_orm::sea_query::ColumnType {
-        sea_orm::sea_query::ColumnType::Binary(sea_orm::sea_query::BlobSize::Long)
-    }
-}
-
-impl sea_orm::sea_query::Nullable for JpegPhoto {
-    fn null() -> sea_orm::Value {
-        JpegPhoto::null().into()
-    }
-}
-
-impl sea_orm::entity::IntoActiveValue<JpegPhoto> for JpegPhoto {
-    fn into_active_value(self) -> sea_orm::ActiveValue<JpegPhoto> {
-        sea_orm::ActiveValue::Set(self)
-    }
-}
-
-impl sea_orm::sea_query::value::ValueType for Uuid {
-    fn try_from(v: sea_orm::Value) -> Result<Self, sea_orm::sea_query::ValueTypeErr> {
-        <super::handler::Uuid as std::convert::TryFrom<_>>::try_from(
-            <std::string::String as sea_orm::sea_query::ValueType>::try_from(v)?.as_str(),
-        )
-        .map_err(|_| sea_orm::sea_query::ValueTypeErr {})
-    }
-
-    fn type_name() -> String {
-        "Uuid".to_owned()
-    }
-
-    fn array_type() -> sea_orm::sea_query::ArrayType {
-        sea_orm::sea_query::ArrayType::String
-    }
-
-    fn column_type() -> sea_orm::sea_query::ColumnType {
-        sea_orm::sea_query::ColumnType::String(Some(36))
-    }
-}
-
 impl From<SchemaVersion> for Value {
     fn from(version: SchemaVersion) -> Self {
         version.0.into()
@@ -215,7 +37,10 @@ pub async fn init_table(pool: &DbConnection) -> anyhow::Result<()> {
 
 #[cfg(test)]
 mod tests {
-    use crate::domain::sql_migrations;
+    use crate::domain::{
+        sql_migrations,
+        types::{GroupId, Uuid},
+    };
 
     use super::*;
     use chrono::prelude::*;
diff --git a/server/src/domain/sql_user_backend_handler.rs b/server/src/domain/sql_user_backend_handler.rs
index 8b4e65e..c19c195 100644
--- a/server/src/domain/sql_user_backend_handler.rs
+++ b/server/src/domain/sql_user_backend_handler.rs
@@ -1,11 +1,9 @@
 use super::{
     error::{DomainError, Result},
-    handler::{
-        CreateUserRequest, GroupDetails, GroupId, UpdateUserRequest, User, UserAndGroups,
-        UserBackendHandler, UserId, UserRequestFilter, Uuid,
-    },
+    handler::{CreateUserRequest, UpdateUserRequest, UserBackendHandler, UserRequestFilter},
     model::{self, GroupColumn, UserColumn},
     sql_backend_handler::SqlBackendHandler,
+    types::{GroupDetails, GroupId, User, UserAndGroups, UserId, Uuid},
 };
 use async_trait::async_trait;
 use sea_orm::{
@@ -245,8 +243,8 @@ impl UserBackendHandler for SqlBackendHandler {
 mod tests {
     use super::*;
     use crate::domain::{
-        handler::{JpegPhoto, UserColumn},
         sql_backend_handler::tests::*,
+        types::{JpegPhoto, UserColumn},
     };
 
     #[tokio::test]
diff --git a/server/src/domain/types.rs b/server/src/domain/types.rs
new file mode 100644
index 0000000..76673d8
--- /dev/null
+++ b/server/src/domain/types.rs
@@ -0,0 +1,393 @@
+use sea_orm::{
+    entity::IntoActiveValue,
+    sea_query::{value::ValueType, ArrayType, ColumnType, Nullable, ValueTypeErr},
+    DbErr, FromQueryResult, QueryResult, TryFromU64, TryGetError, TryGetable, Value,
+};
+use serde::{Deserialize, Serialize};
+
+pub use super::model::{GroupColumn, UserColumn};
+
+pub type DateTime = chrono::DateTime<chrono::Utc>;
+
+#[derive(PartialEq, Hash, Eq, Clone, Debug, Default, Serialize, Deserialize)]
+#[serde(try_from = "&str")]
+pub struct Uuid(String);
+
+impl Uuid {
+    pub fn from_name_and_date(name: &str, creation_date: &DateTime) -> Self {
+        Uuid(
+            uuid::Uuid::new_v3(
+                &uuid::Uuid::NAMESPACE_X500,
+                &[name.as_bytes(), creation_date.to_rfc3339().as_bytes()].concat(),
+            )
+            .to_string(),
+        )
+    }
+
+    pub fn as_str(&self) -> &str {
+        &self.0
+    }
+
+    pub fn into_string(self) -> String {
+        self.0
+    }
+}
+
+impl<'a> std::convert::TryFrom<&'a str> for Uuid {
+    type Error = anyhow::Error;
+    fn try_from(s: &'a str) -> anyhow::Result<Self> {
+        Ok(Uuid(uuid::Uuid::parse_str(s)?.to_string()))
+    }
+}
+
+impl std::string::ToString for Uuid {
+    fn to_string(&self) -> String {
+        self.0.clone()
+    }
+}
+
+impl TryGetable for Uuid {
+    fn try_get(res: &QueryResult, pre: &str, col: &str) -> std::result::Result<Self, TryGetError> {
+        Ok(Uuid(String::try_get(res, pre, col)?))
+    }
+}
+
+impl ValueType for Uuid {
+    fn try_from(v: Value) -> Result<Self, ValueTypeErr> {
+        <Self as std::convert::TryFrom<_>>::try_from(
+            <std::string::String as sea_orm::sea_query::ValueType>::try_from(v)?.as_str(),
+        )
+        .map_err(|_| ValueTypeErr {})
+    }
+
+    fn type_name() -> String {
+        "Uuid".to_owned()
+    }
+
+    fn array_type() -> ArrayType {
+        ArrayType::String
+    }
+
+    fn column_type() -> ColumnType {
+        ColumnType::String(Some(36))
+    }
+}
+
+impl From<Uuid> for Value {
+    fn from(uuid: Uuid) -> Self {
+        uuid.as_str().into()
+    }
+}
+
+impl From<&Uuid> for Value {
+    fn from(uuid: &Uuid) -> Self {
+        uuid.as_str().into()
+    }
+}
+
+#[cfg(test)]
+#[macro_export]
+macro_rules! uuid {
+    ($s:literal) => {
+        <$crate::domain::types::Uuid as std::convert::TryFrom<_>>::try_from($s).unwrap()
+    };
+}
+
+#[derive(PartialEq, Eq, Clone, Debug, Default, Serialize, Deserialize)]
+#[serde(from = "String")]
+pub struct UserId(String);
+
+impl UserId {
+    pub fn new(user_id: &str) -> Self {
+        Self(user_id.to_lowercase())
+    }
+
+    pub fn as_str(&self) -> &str {
+        self.0.as_str()
+    }
+
+    pub fn into_string(self) -> String {
+        self.0
+    }
+}
+
+impl std::fmt::Display for UserId {
+    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+        write!(f, "{}", self.0)
+    }
+}
+
+impl From<String> for UserId {
+    fn from(s: String) -> Self {
+        Self::new(&s)
+    }
+}
+
+impl From<UserId> for Value {
+    fn from(user_id: UserId) -> Self {
+        user_id.into_string().into()
+    }
+}
+
+impl From<&UserId> for Value {
+    fn from(user_id: &UserId) -> Self {
+        user_id.as_str().into()
+    }
+}
+
+impl TryGetable for UserId {
+    fn try_get(res: &QueryResult, pre: &str, col: &str) -> Result<Self, TryGetError> {
+        Ok(UserId::new(&String::try_get(res, pre, col)?))
+    }
+}
+
+impl TryFromU64 for UserId {
+    fn try_from_u64(_n: u64) -> Result<Self, DbErr> {
+        Err(DbErr::ConvertFromU64(
+            "UserId cannot be constructed from u64",
+        ))
+    }
+}
+
+impl ValueType for UserId {
+    fn try_from(v: Value) -> Result<Self, ValueTypeErr> {
+        Ok(UserId::new(<String as ValueType>::try_from(v)?.as_str()))
+    }
+
+    fn type_name() -> String {
+        "UserId".to_owned()
+    }
+
+    fn array_type() -> ArrayType {
+        ArrayType::String
+    }
+
+    fn column_type() -> ColumnType {
+        ColumnType::String(Some(255))
+    }
+}
+
+#[derive(PartialEq, Eq, Clone, Debug, Serialize, Deserialize)]
+pub struct JpegPhoto(#[serde(with = "serde_bytes")] Vec<u8>);
+
+impl From<JpegPhoto> for Value {
+    fn from(photo: JpegPhoto) -> Self {
+        photo.0.into()
+    }
+}
+
+impl From<&JpegPhoto> for Value {
+    fn from(photo: &JpegPhoto) -> Self {
+        photo.0.as_slice().into()
+    }
+}
+
+impl TryFrom<&[u8]> for JpegPhoto {
+    type Error = anyhow::Error;
+    fn try_from(bytes: &[u8]) -> anyhow::Result<Self> {
+        if bytes.is_empty() {
+            return Ok(JpegPhoto::null());
+        }
+        // Confirm that it's a valid Jpeg, then store only the bytes.
+        image::io::Reader::with_format(std::io::Cursor::new(bytes), image::ImageFormat::Jpeg)
+            .decode()?;
+        Ok(JpegPhoto(bytes.to_vec()))
+    }
+}
+
+impl TryFrom<Vec<u8>> for JpegPhoto {
+    type Error = anyhow::Error;
+    fn try_from(bytes: Vec<u8>) -> anyhow::Result<Self> {
+        if bytes.is_empty() {
+            return Ok(JpegPhoto::null());
+        }
+        // Confirm that it's a valid Jpeg, then store only the bytes.
+        image::io::Reader::with_format(
+            std::io::Cursor::new(bytes.as_slice()),
+            image::ImageFormat::Jpeg,
+        )
+        .decode()?;
+        Ok(JpegPhoto(bytes))
+    }
+}
+
+impl TryFrom<String> for JpegPhoto {
+    type Error = anyhow::Error;
+    fn try_from(string: String) -> anyhow::Result<Self> {
+        // The String format is in base64.
+        <Self as TryFrom<_>>::try_from(base64::decode(string.as_str())?)
+    }
+}
+
+impl From<&JpegPhoto> for String {
+    fn from(val: &JpegPhoto) -> Self {
+        base64::encode(&val.0)
+    }
+}
+
+impl JpegPhoto {
+    pub fn null() -> Self {
+        Self(vec![])
+    }
+
+    pub fn into_bytes(self) -> Vec<u8> {
+        self.0
+    }
+
+    #[cfg(test)]
+    pub fn for_tests() -> Self {
+        use image::{ImageOutputFormat, Rgb, RgbImage};
+        let img = RgbImage::from_fn(32, 32, |x, y| {
+            if (x + y) % 2 == 0 {
+                Rgb([0, 0, 0])
+            } else {
+                Rgb([255, 255, 255])
+            }
+        });
+        let mut bytes: Vec<u8> = Vec::new();
+        img.write_to(
+            &mut std::io::Cursor::new(&mut bytes),
+            ImageOutputFormat::Jpeg(0),
+        )
+        .unwrap();
+        Self(bytes)
+    }
+}
+
+impl TryGetable for JpegPhoto {
+    fn try_get(res: &QueryResult, pre: &str, col: &str) -> Result<Self, TryGetError> {
+        <Self as std::convert::TryFrom<Vec<_>>>::try_from(Vec::<u8>::try_get(res, pre, col)?)
+            .map_err(|e| {
+                TryGetError::DbErr(DbErr::TryIntoErr {
+                    from: "[u8]",
+                    into: "JpegPhoto",
+                    source: e.into(),
+                })
+            })
+    }
+}
+
+impl ValueType for JpegPhoto {
+    fn try_from(v: Value) -> Result<Self, ValueTypeErr> {
+        <Self as std::convert::TryFrom<_>>::try_from(
+            <Vec<u8> as sea_orm::sea_query::ValueType>::try_from(v)?.as_slice(),
+        )
+        .map_err(|_| ValueTypeErr {})
+    }
+
+    fn type_name() -> String {
+        "JpegPhoto".to_owned()
+    }
+
+    fn array_type() -> ArrayType {
+        ArrayType::Bytes
+    }
+
+    fn column_type() -> ColumnType {
+        ColumnType::Binary(sea_orm::sea_query::BlobSize::Long)
+    }
+}
+
+impl Nullable for JpegPhoto {
+    fn null() -> Value {
+        JpegPhoto::null().into()
+    }
+}
+
+impl IntoActiveValue<JpegPhoto> for JpegPhoto {
+    fn into_active_value(self) -> sea_orm::ActiveValue<JpegPhoto> {
+        sea_orm::ActiveValue::Set(self)
+    }
+}
+
+#[derive(PartialEq, Eq, Debug, Clone, Serialize, Deserialize, FromQueryResult)]
+pub struct User {
+    pub user_id: UserId,
+    pub email: String,
+    pub display_name: Option<String>,
+    pub first_name: Option<String>,
+    pub last_name: Option<String>,
+    pub avatar: Option<JpegPhoto>,
+    pub creation_date: DateTime,
+    pub uuid: Uuid,
+}
+
+#[cfg(test)]
+impl Default for User {
+    fn default() -> Self {
+        use chrono::TimeZone;
+        let epoch = chrono::Utc.timestamp_opt(0, 0).unwrap();
+        User {
+            user_id: UserId::default(),
+            email: String::new(),
+            display_name: None,
+            first_name: None,
+            last_name: None,
+            avatar: None,
+            creation_date: epoch,
+            uuid: Uuid::from_name_and_date("", &epoch),
+        }
+    }
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash, Serialize, Deserialize)]
+pub struct GroupId(pub i32);
+
+impl From<GroupId> for Value {
+    fn from(group_id: GroupId) -> Self {
+        group_id.0.into()
+    }
+}
+
+impl TryGetable for GroupId {
+    fn try_get(res: &QueryResult, pre: &str, col: &str) -> Result<Self, TryGetError> {
+        Ok(GroupId(i32::try_get(res, pre, col)?))
+    }
+}
+
+impl ValueType for GroupId {
+    fn try_from(v: Value) -> Result<Self, ValueTypeErr> {
+        Ok(GroupId(<i32 as ValueType>::try_from(v)?))
+    }
+
+    fn type_name() -> String {
+        "GroupId".to_owned()
+    }
+
+    fn array_type() -> ArrayType {
+        ArrayType::Int
+    }
+
+    fn column_type() -> ColumnType {
+        ColumnType::Integer(None)
+    }
+}
+
+impl TryFromU64 for GroupId {
+    fn try_from_u64(n: u64) -> Result<Self, DbErr> {
+        Ok(GroupId(i32::try_from_u64(n)?))
+    }
+}
+
+#[derive(PartialEq, Eq, Debug, Serialize, Deserialize)]
+pub struct Group {
+    pub id: GroupId,
+    pub display_name: String,
+    pub creation_date: DateTime,
+    pub uuid: Uuid,
+    pub users: Vec<UserId>,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Hash, Serialize, Deserialize, FromQueryResult)]
+pub struct GroupDetails {
+    pub group_id: GroupId,
+    pub display_name: String,
+    pub creation_date: DateTime,
+    pub uuid: Uuid,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct UserAndGroups {
+    pub user: User,
+    pub groups: Option<Vec<GroupDetails>>,
+}
diff --git a/server/src/infra/auth_service.rs b/server/src/infra/auth_service.rs
index 207d1fb..e8f8c7e 100644
--- a/server/src/infra/auth_service.rs
+++ b/server/src/infra/auth_service.rs
@@ -22,12 +22,12 @@ use tracing::{debug, instrument, warn};
 
 use lldap_auth::{login, password_reset, registration, JWTClaims};
 
-use crate::domain::handler::UserRequestFilter;
 use crate::{
     domain::{
         error::DomainError,
-        handler::{BackendHandler, BindRequest, GroupDetails, LoginHandler, UserColumn, UserId},
+        handler::{BackendHandler, BindRequest, LoginHandler, UserRequestFilter},
         opaque_handler::OpaqueHandler,
+        types::{GroupDetails, UserColumn, UserId},
     },
     infra::{
         tcp_backend_handler::*,
diff --git a/server/src/infra/configuration.rs b/server/src/infra/configuration.rs
index bfdc3ee..209adbe 100644
--- a/server/src/infra/configuration.rs
+++ b/server/src/infra/configuration.rs
@@ -1,5 +1,5 @@
 use crate::{
-    domain::handler::UserId,
+    domain::types::UserId,
     infra::cli::{GeneralConfigOpts, LdapsOpts, RunOpts, SmtpEncryption, SmtpOpts, TestEmailOpts},
 };
 use anyhow::{Context, Result};
diff --git a/server/src/infra/graphql/mutation.rs b/server/src/infra/graphql/mutation.rs
index 74ed3b2..9a25013 100644
--- a/server/src/infra/graphql/mutation.rs
+++ b/server/src/infra/graphql/mutation.rs
@@ -1,6 +1,6 @@
-use crate::domain::handler::{
-    BackendHandler, CreateUserRequest, GroupId, JpegPhoto, UpdateGroupRequest, UpdateUserRequest,
-    UserId,
+use crate::domain::{
+    handler::{BackendHandler, CreateUserRequest, UpdateGroupRequest, UpdateUserRequest},
+    types::{GroupId, JpegPhoto, UserId},
 };
 use anyhow::Context as AnyhowContext;
 use juniper::{graphql_object, FieldResult, GraphQLInputObject, GraphQLObject};
diff --git a/server/src/infra/graphql/query.rs b/server/src/infra/graphql/query.rs
index 4754ee6..03091f6 100644
--- a/server/src/infra/graphql/query.rs
+++ b/server/src/infra/graphql/query.rs
@@ -1,15 +1,16 @@
 use crate::domain::{
-    handler::{BackendHandler, GroupDetails, GroupId, UserColumn, UserId},
+    handler::BackendHandler,
     ldap::utils::map_user_field,
+    types::{GroupDetails, GroupId, UserColumn, UserId},
 };
 use juniper::{graphql_object, FieldResult, GraphQLInputObject};
 use serde::{Deserialize, Serialize};
 use tracing::{debug, debug_span, Instrument};
 
 type DomainRequestFilter = crate::domain::handler::UserRequestFilter;
-type DomainUser = crate::domain::handler::User;
-type DomainGroup = crate::domain::handler::Group;
-type DomainUserAndGroups = crate::domain::handler::UserAndGroups;
+type DomainUser = crate::domain::types::User;
+type DomainGroup = crate::domain::types::Group;
+type DomainUserAndGroups = crate::domain::types::UserAndGroups;
 use super::api::Context;
 
 #[derive(PartialEq, Eq, Debug, GraphQLInputObject)]
@@ -345,10 +346,7 @@ impl<Handler: BackendHandler> From<DomainGroup> for Group<Handler> {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::{
-        domain::handler::{MockTestBackendHandler, UserRequestFilter},
-        infra::auth_service::ValidationResults,
-    };
+    use crate::{domain::handler::MockTestBackendHandler, infra::auth_service::ValidationResults};
     use chrono::TimeZone;
     use juniper::{
         execute, graphql_value, DefaultScalarValue, EmptyMutation, EmptySubscription, GraphQLType,
@@ -457,9 +455,12 @@ mod tests {
         let mut mock = MockTestBackendHandler::new();
         mock.expect_list_users()
             .with(
-                eq(Some(UserRequestFilter::Or(vec![
-                    UserRequestFilter::UserId(UserId::new("bob")),
-                    UserRequestFilter::Equality(UserColumn::Email, "robert@bobbers.on".to_string()),
+                eq(Some(DomainRequestFilter::Or(vec![
+                    DomainRequestFilter::UserId(UserId::new("bob")),
+                    DomainRequestFilter::Equality(
+                        UserColumn::Email,
+                        "robert@bobbers.on".to_string(),
+                    ),
                 ]))),
                 eq(false),
             )
diff --git a/server/src/infra/ldap_handler.rs b/server/src/infra/ldap_handler.rs
index 94b7e93..790d2e2 100644
--- a/server/src/infra/ldap_handler.rs
+++ b/server/src/infra/ldap_handler.rs
@@ -1,10 +1,6 @@
-use std::collections::HashMap;
-
 use crate::{
     domain::{
-        handler::{
-            BackendHandler, BindRequest, CreateUserRequest, JpegPhoto, LoginHandler, UserId,
-        },
+        handler::{BackendHandler, BindRequest, CreateUserRequest, LoginHandler},
         ldap::{
             error::{LdapError, LdapResult},
             group::get_groups_list,
@@ -14,6 +10,7 @@ use crate::{
             },
         },
         opaque_handler::OpaqueHandler,
+        types::{JpegPhoto, UserId},
     },
     infra::auth_service::{Permission, ValidationResults},
 };
@@ -24,6 +21,7 @@ use ldap3_proto::proto::{
     LdapResult as LdapResultOp, LdapResultCode, LdapSearchRequest, LdapSearchResultEntry,
     LdapSearchScope,
 };
+use std::collections::HashMap;
 use tracing::{debug, instrument, warn};
 
 #[derive(Debug, PartialEq, Eq, Clone)]
@@ -569,7 +567,7 @@ impl<Backend: BackendHandler + LoginHandler + OpaqueHandler> LdapHandler<Backend
 mod tests {
     use super::*;
     use crate::{
-        domain::{error::Result, handler::*, opaque_handler::*},
+        domain::{error::Result, handler::*, opaque_handler::*, types::*},
         uuid,
     };
     use async_trait::async_trait;
diff --git a/server/src/infra/sql_backend_handler.rs b/server/src/infra/sql_backend_handler.rs
index c87d865..91741cc 100644
--- a/server/src/infra/sql_backend_handler.rs
+++ b/server/src/infra/sql_backend_handler.rs
@@ -1,9 +1,9 @@
 use super::tcp_backend_handler::TcpBackendHandler;
 use crate::domain::{
     error::*,
-    handler::UserId,
     model::{self, JwtRefreshStorageColumn, JwtStorageColumn, PasswordResetTokensColumn},
     sql_backend_handler::SqlBackendHandler,
+    types::UserId,
 };
 use async_trait::async_trait;
 use sea_orm::{
diff --git a/server/src/infra/tcp_backend_handler.rs b/server/src/infra/tcp_backend_handler.rs
index 8bdf97d..f4930af 100644
--- a/server/src/infra/tcp_backend_handler.rs
+++ b/server/src/infra/tcp_backend_handler.rs
@@ -1,7 +1,7 @@
 use async_trait::async_trait;
 use std::collections::HashSet;
 
-use crate::domain::{error::Result, handler::UserId};
+use crate::domain::{error::Result, types::UserId};
 
 #[async_trait]
 pub trait TcpBackendHandler {
@@ -22,7 +22,7 @@ pub trait TcpBackendHandler {
 }
 
 #[cfg(test)]
-use crate::domain::handler::*;
+use crate::domain::{handler::*, types::*};
 #[cfg(test)]
 mockall::mock! {
     pub TestTcpBackendHandler{}