diff --git a/docker-compose.dev.yml b/docker-compose.dev.yml
index bb7c649..3cced03 100644
--- a/docker-compose.dev.yml
+++ b/docker-compose.dev.yml
@@ -5,7 +5,7 @@ services:
   book-a-book-eureka:
     image: aleixmt/book-a-book-eureka:latest
     ports:
-      - "0.0.0.0:8761:8761"
+      - "0.0.0.0:8762:8761"
     restart: unless-stopped
     pull_policy: always
     healthcheck:
diff --git a/pom.xml b/pom.xml
index 5b37a70..4ac0b8c 100644
--- a/pom.xml
+++ b/pom.xml
@@ -66,6 +66,12 @@
 			<groupId>org.springframework.boot</groupId>
 			<artifactId>spring-boot-starter-data-jpa</artifactId>
 		</dependency>
+
+		<dependency>
+			<groupId>io.github.openfeign</groupId>
+			<artifactId>feign-okhttp</artifactId>
+			<version>13.2</version>
+		</dependency>
 	</dependencies>
 
 	<build>
diff --git a/src/main/java/net/unir/missi/desarrollowebfullstack/bookabook/operador/clients/BuscadorClient.java b/src/main/java/net/unir/missi/desarrollowebfullstack/bookabook/operador/clients/BuscadorClient.java
index c04aee1..b5a2d59 100644
--- a/src/main/java/net/unir/missi/desarrollowebfullstack/bookabook/operador/clients/BuscadorClient.java
+++ b/src/main/java/net/unir/missi/desarrollowebfullstack/bookabook/operador/clients/BuscadorClient.java
@@ -1,5 +1,6 @@
 package net.unir.missi.desarrollowebfullstack.bookabook.operador.clients;
 
+import net.unir.missi.desarrollowebfullstack.bookabook.operador.config.FeignConfig;
 import net.unir.missi.desarrollowebfullstack.bookabook.operador.model.api.*;
 import org.springframework.cloud.openfeign.FeignClient;
 import org.springframework.http.ResponseEntity;
@@ -9,9 +10,10 @@
 import java.util.List;
 import java.util.Map;
 
-@FeignClient(name = "buscador")
+@FeignClient(name = "buscador", url = "http://localhost:8082/",configuration = FeignConfig.class)
 public interface BuscadorClient {
 
+
     // Authors
 
     @GetMapping("/authors")
diff --git a/src/main/java/net/unir/missi/desarrollowebfullstack/bookabook/operador/config/FeignConfig.java b/src/main/java/net/unir/missi/desarrollowebfullstack/bookabook/operador/config/FeignConfig.java
index fa91680..2e1b22f 100644
--- a/src/main/java/net/unir/missi/desarrollowebfullstack/bookabook/operador/config/FeignConfig.java
+++ b/src/main/java/net/unir/missi/desarrollowebfullstack/bookabook/operador/config/FeignConfig.java
@@ -1,8 +1,12 @@
 package net.unir.missi.desarrollowebfullstack.bookabook.operador.config;
 
-import org.springframework.cloud.openfeign.EnableFeignClients;
+import feign.Logger;
+import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 
 @Configuration
 public class FeignConfig {
+
+    @Bean
+    Logger.Level feingLoggerLevel(){ return Logger.Level.FULL; }
 }
diff --git a/src/main/java/net/unir/missi/desarrollowebfullstack/bookabook/operador/config/LoanMerger.java b/src/main/java/net/unir/missi/desarrollowebfullstack/bookabook/operador/config/LoanMerger.java
new file mode 100644
index 0000000..8028669
--- /dev/null
+++ b/src/main/java/net/unir/missi/desarrollowebfullstack/bookabook/operador/config/LoanMerger.java
@@ -0,0 +1,18 @@
+package net.unir.missi.desarrollowebfullstack.bookabook.operador.config;
+
+import net.unir.missi.desarrollowebfullstack.bookabook.operador.model.sql.Loan;
+import org.springframework.context.annotation.Configuration;
+@Configuration
+public class LoanMerger {
+    public Loan merge(Loan destiny, Loan source)
+    {
+        destiny.setBookId(source.getBookId());
+        destiny.setClientId(source.getClientId());
+        destiny.setDueDate(source.getDueDate());
+        destiny.setLoanDate(source.getLoanDate());
+        destiny.setIsReturned(source.getIsReturned());
+        destiny.setRenewalCount(source.getRenewalCount());
+        destiny.setReturnDate(source.getReturnDate());
+        return destiny;
+    }
+}
\ No newline at end of file
diff --git a/src/main/java/net/unir/missi/desarrollowebfullstack/bookabook/operador/config/LoanMergerNonEmpty.java b/src/main/java/net/unir/missi/desarrollowebfullstack/bookabook/operador/config/LoanMergerNonEmpty.java
new file mode 100644
index 0000000..be84b91
--- /dev/null
+++ b/src/main/java/net/unir/missi/desarrollowebfullstack/bookabook/operador/config/LoanMergerNonEmpty.java
@@ -0,0 +1,46 @@
+package net.unir.missi.desarrollowebfullstack.bookabook.operador.config;
+
+import net.unir.missi.desarrollowebfullstack.bookabook.operador.model.sql.Loan;
+import org.springframework.context.annotation.Configuration;
+
+@Configuration
+public class LoanMergerNonEmpty {
+    public Loan merge(Loan destiny, Loan source)
+    {
+        if (source.getBookId() != null && source.getBookId() != 0)
+        {
+            destiny.setBookId(source.getBookId());
+        }
+
+        if (source.getClientId() != null && source.getClientId() != 0)
+        {
+            destiny.setClientId(source.getClientId());
+        }
+
+        if (source.getDueDate() != null)
+        {
+            destiny.setDueDate(source.getDueDate());
+        }
+
+        if (source.getLoanDate() != null)
+        {
+            destiny.setLoanDate(source.getLoanDate());
+        }
+
+        if (source.getIsReturned() != null)
+        {
+            destiny.setIsReturned(source.getIsReturned());
+        }
+
+        if (source.getRenewalCount() != null)
+        {
+            destiny.setRenewalCount(source.getRenewalCount());
+        }
+
+        if (source.getReturnDate() != null)
+        {
+            destiny.setReturnDate(source.getReturnDate());
+        }
+        return destiny;
+    }
+}
\ No newline at end of file
diff --git a/src/main/java/net/unir/missi/desarrollowebfullstack/bookabook/operador/config/LoanRequestToLoanConverter.java b/src/main/java/net/unir/missi/desarrollowebfullstack/bookabook/operador/config/LoanRequestToLoanConverter.java
new file mode 100644
index 0000000..3a4a860
--- /dev/null
+++ b/src/main/java/net/unir/missi/desarrollowebfullstack/bookabook/operador/config/LoanRequestToLoanConverter.java
@@ -0,0 +1,22 @@
+package net.unir.missi.desarrollowebfullstack.bookabook.operador.config;
+
+import net.unir.missi.desarrollowebfullstack.bookabook.operador.model.api.LoanRequest;
+import net.unir.missi.desarrollowebfullstack.bookabook.operador.model.sql.Loan;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.core.convert.converter.Converter;
+
+@Configuration
+public class LoanRequestToLoanConverter implements Converter<LoanRequest, Loan> {
+    @Override
+    public Loan convert(LoanRequest source) {
+        return Loan.builder()
+                .bookId(source.getBookId())
+                .clientId(source.getClientId())
+                .loanDate(source.getLoanDate())
+                .dueDate(source.getDueDate())
+                .returnDate(source.getReturnDate())
+                .isReturned(source.getIsReturned())
+                .renewalCount(source.getRenewalCount())
+                .build();
+    }
+}
\ No newline at end of file
diff --git a/src/main/java/net/unir/missi/desarrollowebfullstack/bookabook/operador/config/LoanToLoanResponseConverter.java b/src/main/java/net/unir/missi/desarrollowebfullstack/bookabook/operador/config/LoanToLoanResponseConverter.java
new file mode 100644
index 0000000..5f33084
--- /dev/null
+++ b/src/main/java/net/unir/missi/desarrollowebfullstack/bookabook/operador/config/LoanToLoanResponseConverter.java
@@ -0,0 +1,23 @@
+package net.unir.missi.desarrollowebfullstack.bookabook.operador.config;
+
+import net.unir.missi.desarrollowebfullstack.bookabook.operador.model.api.LoanResponse;
+import net.unir.missi.desarrollowebfullstack.bookabook.operador.model.sql.Loan;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.core.convert.converter.Converter;
+
+@Configuration
+public class LoanToLoanResponseConverter implements Converter<Loan, LoanResponse> {
+    @Override
+    public LoanResponse convert(Loan source) {
+        return LoanResponse.builder()
+                .id(source.getId())
+                .bookId(source.getBookId())
+                .clientId(source.getClientId())
+                .loanDate(source.getLoanDate())
+                .dueDate(source.getDueDate())
+                .returnDate(source.getReturnDate())
+                .isReturned(source.getIsReturned())
+                .renewalCount(source.getRenewalCount())
+                .build();
+    }
+}
\ No newline at end of file
diff --git a/src/main/java/net/unir/missi/desarrollowebfullstack/bookabook/operador/controller/LoansController.java b/src/main/java/net/unir/missi/desarrollowebfullstack/bookabook/operador/controller/LoansController.java
index 8c76078..a596104 100644
--- a/src/main/java/net/unir/missi/desarrollowebfullstack/bookabook/operador/controller/LoansController.java
+++ b/src/main/java/net/unir/missi/desarrollowebfullstack/bookabook/operador/controller/LoansController.java
@@ -3,6 +3,8 @@
 import io.swagger.v3.oas.annotations.Parameter;
 import lombok.RequiredArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
+import net.unir.missi.desarrollowebfullstack.bookabook.operador.exceptions.BadParametersException;
+import net.unir.missi.desarrollowebfullstack.bookabook.operador.exceptions.EntityNotFoundException;
 import net.unir.missi.desarrollowebfullstack.bookabook.operador.model.api.LoanRequest;
 import net.unir.missi.desarrollowebfullstack.bookabook.operador.model.api.LoanResponse;
 import net.unir.missi.desarrollowebfullstack.bookabook.operador.service.LoanService;
@@ -22,7 +24,7 @@ public class LoansController {
     private final LoanService service;
 
     @GetMapping("/loans")
-    public ResponseEntity<List<LoanResponse>> getAllLoans(
+    public ResponseEntity<List<LoanResponse>> getLoans(
             @Parameter(name="bookId", example = "")
             @RequestParam(required = false) Long bookId,
             @Parameter(name="clientId", example = "")
@@ -39,52 +41,129 @@ public ResponseEntity<List<LoanResponse>> getAllLoans(
             @RequestParam(required = false)Integer renewalCount
             ) {
 
-            try {
-                List<LoanResponse> response = service.getAllLoans(bookId, clientId, loanDate, returnDate, dueDate, isReturned, renewalCount);
-                return ResponseEntity.ok(Objects.requireNonNullElse(response, Collections.emptyList()));
-            }
-            catch(Exception e) {
-                return ResponseEntity.internalServerError().build();
-            }
+        try
+        {
+            List<LoanResponse> response = this.service.getAllLoans(bookId, clientId, loanDate, returnDate, dueDate, isReturned, renewalCount);
+            return ResponseEntity.ok(Objects.requireNonNullElse(response, Collections.emptyList()));
+        }
+        catch (EntityNotFoundException e)
+        {
+            return ResponseEntity.notFound().build();
+        }
+        catch (BadParametersException e)
+        {
+            return ResponseEntity.badRequest().build();
+        }
+        catch (Exception e)
+        {
+            return ResponseEntity.internalServerError().build();
+        }
+    }
+
+    @GetMapping("/loans/{id}")
+    public ResponseEntity<LoanResponse> getLoan(@PathVariable String id) {
+        try
+        {
+            LoanResponse response = this.service.getLoanById(Long.valueOf(id));
+            return ResponseEntity.ok(response);
+        }
+        catch (EntityNotFoundException e)
+        {
+            return ResponseEntity.notFound().build();
+        }
+        catch (BadParametersException e)
+        {
+            return ResponseEntity.badRequest().build();
+        }
+        catch (Exception e)
+        {
+            return ResponseEntity.internalServerError().build();
+        }
     }
 
     @PostMapping("/loans")
     public ResponseEntity<LoanResponse> addLoan(@RequestBody LoanRequest loanRequest) {
-        try {
-            if(loanRequest != null) {
-                if(!service.validateLoan(loanRequest)) {
-                    return ResponseEntity.notFound().build();
-                }
-                LoanResponse newLoan = service.createLoan(loanRequest);
-                return ResponseEntity.status(HttpStatus.CREATED).body(newLoan);
-            }
-            else
+        try
+        {
+            if (loanRequest == null)
             {
                 return ResponseEntity.badRequest().build();
             }
-        } catch(Exception e) {
+            LoanResponse newLoan = this.service.createLoan(loanRequest);
+            return ResponseEntity.status(HttpStatus.CREATED).body(newLoan);
+        }
+        catch (EntityNotFoundException e)
+        {
+            return ResponseEntity.notFound().build();
+        }
+        catch (BadParametersException e)
+        {
+            return ResponseEntity.badRequest().build();
+        }
+        catch (Exception e)
+        {
             return ResponseEntity.internalServerError().build();
         }
     }
 
-    @GetMapping("/loans/{id}")
-    public ResponseEntity<LoanResponse> getLoanById(Long id) {
-        try {
-            LoanResponse response = service.getLoanById(id);
-            return ResponseEntity.ok(response);
+    @DeleteMapping("/loans/{id}")
+    public ResponseEntity<LoanResponse> deleteLoan(@PathVariable String id) {
+        try
+        {
+            return ResponseEntity.ok(this.service.deleteLoan(id));
+        }
+        catch (EntityNotFoundException e)
+        {
+            return ResponseEntity.notFound().build();
+        }
+        catch (Exception e)
+        {
+            return ResponseEntity.internalServerError().build();
+        }
+    }
+
+    @PatchMapping("/loans/{id}")
+    public ResponseEntity<LoanResponse> patchLoan(@RequestBody LoanRequest loanRequest, @PathVariable String id) {
+        try
+        {
+            if (loanRequest == null)
+            {
+                return ResponseEntity.badRequest().build();
+            }
+            LoanResponse newLoan = this.service.modifyLoan(loanRequest, Long.valueOf(id));
+            return ResponseEntity.status(HttpStatus.CREATED).body(newLoan);
         }
-        catch(Exception e) {
+        catch (EntityNotFoundException e)
+        {
+            return ResponseEntity.notFound().build();
+        }
+        catch (BadParametersException e)
+        {
+            return ResponseEntity.badRequest().build();
+        }
+        catch (Exception e)
+        {
             return ResponseEntity.internalServerError().build();
         }
     }
 
     @GetMapping("/loans/client/{clientId}")
-    public ResponseEntity<List<LoanResponse>> getLoanByClientId(Long clientId) {
-        try {
-            List<LoanResponse> response = service.getLoansByClientId(clientId);
+    public ResponseEntity<List<LoanResponse>> getLoanByClientId(@PathVariable String clientId) {
+        try
+        {
+            List<LoanResponse> response = service.getLoansByClientId(Long.valueOf(clientId));
             return ResponseEntity.ok(Objects.requireNonNullElse(response, Collections.emptyList()));
         }
-        catch(Exception e) {
+        catch (EntityNotFoundException e)
+        {
+            return ResponseEntity.notFound().build();
+        }
+        catch (BadParametersException e)
+        {
+            return ResponseEntity.badRequest().build();
+        }
+        catch(Exception e)
+        {
             return ResponseEntity.internalServerError().build();
         }
     }
diff --git a/src/main/java/net/unir/missi/desarrollowebfullstack/bookabook/operador/exceptions/BadParametersException.java b/src/main/java/net/unir/missi/desarrollowebfullstack/bookabook/operador/exceptions/BadParametersException.java
new file mode 100644
index 0000000..d582f9b
--- /dev/null
+++ b/src/main/java/net/unir/missi/desarrollowebfullstack/bookabook/operador/exceptions/BadParametersException.java
@@ -0,0 +1,8 @@
+package net.unir.missi.desarrollowebfullstack.bookabook.operador.exceptions;
+
+public class BadParametersException extends RuntimeException{
+    public BadParametersException(String errorMessage, Throwable err)
+    {
+        super(errorMessage, err);
+    }
+}
diff --git a/src/main/java/net/unir/missi/desarrollowebfullstack/bookabook/operador/exceptions/EntityNotFoundException.java b/src/main/java/net/unir/missi/desarrollowebfullstack/bookabook/operador/exceptions/EntityNotFoundException.java
new file mode 100644
index 0000000..96a99cf
--- /dev/null
+++ b/src/main/java/net/unir/missi/desarrollowebfullstack/bookabook/operador/exceptions/EntityNotFoundException.java
@@ -0,0 +1,8 @@
+package net.unir.missi.desarrollowebfullstack.bookabook.operador.exceptions;
+
+public class EntityNotFoundException extends RuntimeException{
+    public EntityNotFoundException(String errorMessage, Throwable err)
+    {
+        super(errorMessage, err);
+    }
+}
\ No newline at end of file
diff --git a/src/main/java/net/unir/missi/desarrollowebfullstack/bookabook/operador/model/sql/Loan.java b/src/main/java/net/unir/missi/desarrollowebfullstack/bookabook/operador/model/sql/Loan.java
index 282c4a6..9f15221 100644
--- a/src/main/java/net/unir/missi/desarrollowebfullstack/bookabook/operador/model/sql/Loan.java
+++ b/src/main/java/net/unir/missi/desarrollowebfullstack/bookabook/operador/model/sql/Loan.java
@@ -1 +1,44 @@
-    private Long bookId;
\ No newline at end of file
+package net.unir.missi.desarrollowebfullstack.bookabook.operador.model.sql;
+
+import java.util.Date;
+import jakarta.persistence.Column;
+import jakarta.persistence.Entity;
+import jakarta.persistence.GeneratedValue;
+import jakarta.persistence.GenerationType;
+import jakarta.persistence.Id;
+import jakarta.persistence.Table;
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+import lombok.Setter;
+import lombok.ToString;
+
+
+@Entity
+@Table(name = "loans")
+@Getter
+@Setter
+@AllArgsConstructor
+@NoArgsConstructor
+@Builder
+@ToString
+public class Loan {
+    @Id
+    @GeneratedValue(strategy = GenerationType.AUTO)
+    private Long id;
+    @Column(name = "bookId")
+    private Long bookId;
+    @Column(name = "clientId")
+    private Long clientId;
+    @Column(name = "loanDate")
+    private Date loanDate;
+    @Column(name = "returnDate")
+    private Date returnDate;
+    @Column(name = "dueDate")
+    private Date dueDate;
+    @Column(name = "isReturned")
+    private Boolean isReturned;
+    @Column(name = "renewalCount")
+    private Integer renewalCount;
+}
diff --git a/src/main/java/net/unir/missi/desarrollowebfullstack/bookabook/operador/repository/LoanRepository.java b/src/main/java/net/unir/missi/desarrollowebfullstack/bookabook/operador/repository/LoanRepository.java
index 020c0f9..24a1fed 100644
--- a/src/main/java/net/unir/missi/desarrollowebfullstack/bookabook/operador/repository/LoanRepository.java
+++ b/src/main/java/net/unir/missi/desarrollowebfullstack/bookabook/operador/repository/LoanRepository.java
@@ -11,6 +11,7 @@
 
 import java.util.Date;
 import java.util.List;
+import java.util.Optional;
 
 @Repository
 @Slf4j
@@ -26,7 +27,12 @@ public LoanRepository(LoanJpaRepository loanJpaRepository) {
     public Loan findById(Long id) { return loanJpaRepository.findById(id).orElse(null); }
     public List<Loan> findByClientId(Long clientId){ return loanJpaRepository.findByClientId(clientId); }
     public Loan save(Loan loan){ return loanJpaRepository.save(loan); }
-    public void delete(Loan loan) { loanJpaRepository.delete(loan); }
+    public Loan delete(Loan loan)
+    {
+        Optional<Loan> l = this.loanJpaRepository.findById(loan.getId());
+        loanJpaRepository.delete(loan);
+        return l.get();
+    }
 
     public List<Loan> search(Long bookId, Long clientId, Date loanDate, Date returnDate, Date dueDate, Boolean isReturned, Integer renewalCount) {
         SearchCriteria<Loan> spec = new SearchCriteria<>();
diff --git a/src/main/java/net/unir/missi/desarrollowebfullstack/bookabook/operador/service/ILoanService.java b/src/main/java/net/unir/missi/desarrollowebfullstack/bookabook/operador/service/ILoanService.java
index 87d11f9..430fb72 100644
--- a/src/main/java/net/unir/missi/desarrollowebfullstack/bookabook/operador/service/ILoanService.java
+++ b/src/main/java/net/unir/missi/desarrollowebfullstack/bookabook/operador/service/ILoanService.java
@@ -7,11 +7,14 @@
 import java.util.List;
 
 public interface ILoanService {
-    List<LoanResponse> getAllLoans(Long bookId, Long clientId, Date loanDate, Date returnDate, Date dueDate, Boolean isReturned, Integer renewalCount) throws RuntimeException;
-    LoanResponse createLoan(LoanRequest request) throws RuntimeException;
-    LoanResponse getLoanById(Long id) throws RuntimeException;
-    List<LoanResponse> getLoansByClientId(Long clientId) throws RuntimeException;
-    LoanResponse modifyAllLoanData(LoanRequest preData, LoanRequest loanData) throws RuntimeException;
-    LoanResponse modifyLoan(LoanRequest preData, LoanRequest loanData) throws RuntimeException;
-    LoanResponse deleteLoan(LoanRequest preData, LoanRequest loanData) throws RuntimeException;
+    // CRUD
+    List<LoanResponse> getAllLoans(Long bookId, Long clientId, Date loanDate, Date returnDate, Date dueDate, Boolean isReturned, Integer renewalCount);
+    LoanResponse createLoan(LoanRequest request);
+    LoanResponse getLoanById(Long id);
+    LoanResponse modifyAllLoanData(LoanRequest loan, Long id);
+    LoanResponse modifyLoan(LoanRequest loan, Long id);
+    LoanResponse deleteLoan(String id);
+
+    // SPECIALIZATIONS
+    List<LoanResponse> getLoansByClientId(Long clientId);
 }
diff --git a/src/main/java/net/unir/missi/desarrollowebfullstack/bookabook/operador/service/LoanService.java b/src/main/java/net/unir/missi/desarrollowebfullstack/bookabook/operador/service/LoanService.java
index 6e70efb..5850872 100644
--- a/src/main/java/net/unir/missi/desarrollowebfullstack/bookabook/operador/service/LoanService.java
+++ b/src/main/java/net/unir/missi/desarrollowebfullstack/bookabook/operador/service/LoanService.java
@@ -1 +1,255 @@
-    public LoanResponse modifyAllLoanData(LoanRequest preData, LoanRequest loanData) throws RuntimeException {
\ No newline at end of file
+package net.unir.missi.desarrollowebfullstack.bookabook.operador.service;
+
+import lombok.extern.slf4j.Slf4j;
+import net.unir.missi.desarrollowebfullstack.bookabook.operador.clients.BuscadorClient;
+import net.unir.missi.desarrollowebfullstack.bookabook.operador.config.LoanMerger;
+import net.unir.missi.desarrollowebfullstack.bookabook.operador.config.LoanMergerNonEmpty;
+import net.unir.missi.desarrollowebfullstack.bookabook.operador.config.LoanRequestToLoanConverter;
+import net.unir.missi.desarrollowebfullstack.bookabook.operador.config.LoanToLoanResponseConverter;
+import net.unir.missi.desarrollowebfullstack.bookabook.operador.exceptions.BadParametersException;
+import net.unir.missi.desarrollowebfullstack.bookabook.operador.exceptions.EntityNotFoundException;
+import net.unir.missi.desarrollowebfullstack.bookabook.operador.model.api.BookResponse;
+import net.unir.missi.desarrollowebfullstack.bookabook.operador.model.api.ClientResponse;
+import net.unir.missi.desarrollowebfullstack.bookabook.operador.model.api.LoanRequest;
+import net.unir.missi.desarrollowebfullstack.bookabook.operador.model.api.LoanResponse;
+import net.unir.missi.desarrollowebfullstack.bookabook.operador.model.sql.Loan;
+import net.unir.missi.desarrollowebfullstack.bookabook.operador.repository.LoanRepository;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.http.ResponseEntity;
+import org.springframework.stereotype.Service;
+
+import java.awt.print.Book;
+import java.util.ArrayList;
+import java.util.Date;
+import java.util.List;
+import java.util.Objects;
+import java.util.logging.Logger;
+import java.util.stream.Collectors;
+
+@Service
+@Slf4j
+public class LoanService implements ILoanService {
+
+    @Autowired
+    private LoanRepository loanRepository;
+
+    @Autowired
+    private BuscadorClient buscadorClient;
+
+    @Autowired
+    private LoanRequestToLoanConverter loanRequestToLoanConverter;
+
+    @Autowired
+    private LoanToLoanResponseConverter loanToLoanResponseConverter;
+
+    @Autowired
+    private LoanMerger loanMerger;
+
+    @Autowired
+    private LoanMergerNonEmpty loanMergerNonEmpty;
+
+    // CRUD
+
+    @Override
+    public List<LoanResponse> getAllLoans(Long bookId, Long clientId, Date loanDate, Date returnDate, Date dueDate, Boolean isReturned, Integer renewalCount) {
+        Loan loan = new Loan(null, bookId, clientId, loanDate, returnDate, dueDate, isReturned, renewalCount);
+        List<Loan> loanList;
+        if (this.isValidSyntaxLoanForNulls(loan)) {
+            loanList = loanRepository.search(bookId, clientId, loanDate, returnDate, dueDate, isReturned, renewalCount);
+        }
+        else {
+            loanList = loanRepository.findAll();
+        }
+        return loanList.stream().map((Loan l) -> this.loanToLoanResponseConverter.convert(l)).collect(Collectors.toList());
+    }
+
+    @Override
+    public LoanResponse createLoan(LoanRequest request) {
+        // Convert to in-memory loan
+        Loan loan = this.loanRequestToLoanConverter.convert(request);
+
+        // If loan has null values or wrong values throw 400
+        if (!this.isValidSyntaxLoanForNulls(Objects.requireNonNull(loan))
+                        || ! this.isValidSyntaxLoanForZeroes(loan))
+        {
+            throw new BadParametersException("One or more parameters of the request are wrong", null);
+        }
+
+        // If loan referencing non-existing books throw 404
+        if (! isExistingBook(loan.getBookId().toString()))
+        {
+            throw new EntityNotFoundException("Book id " + loan.getBookId() + " does not exist.", null);
+        }
+
+        // If loan referencing non-existing clients throw 404
+        if(! isExistingClient(loan.getClientId().toString()))
+        {
+            throw new EntityNotFoundException("Client id " + loan.getClientId() + " does not exist.", null);
+        }
+
+        // Implicit else: valid loan is saved in the DB
+        Loan createdLoan = loanRepository.save(loan);
+        return this.loanToLoanResponseConverter.convert(createdLoan);
+    }
+
+    @Override
+    public LoanResponse getLoanById(Long id) {
+        // If loan does not exist throw 404
+        Loan loan = loanRepository.findById(id);
+        if (loan == null)
+        {
+            throw new EntityNotFoundException("Loan with id " + id.toString() + " does not exist", null);
+        }
+
+        return this.loanToLoanResponseConverter.convert(loan);
+    }
+
+    @Override
+    public LoanResponse modifyAllLoanData(LoanRequest loanRequest, Long id) {
+        Loan loan = this.loanRequestToLoanConverter.convert(loanRequest);
+
+        // If loan has null values or wrong values throw 400
+        if (
+                ! this.isValidSyntaxLoanForNulls(Objects.requireNonNull(loan))
+                        || ! this.isValidSyntaxLoanForZeroes(loan))
+        {
+            throw new BadParametersException("One or more parameters of the request are wrong", null);
+        }
+
+        // If loan does not exist throw 404
+        Loan loanMatched = loanRepository.findById(id);
+        if (loanMatched == null)
+        {
+            throw new EntityNotFoundException("Loan with id " + id.toString() + " does not exist", null);
+        }
+
+        // If loan referencing non-existing books throw 404
+        if (! isExistingBook(loan.getBookId().toString()))
+        {
+            throw new EntityNotFoundException("Book id " + loan.getBookId() + " does not exist.", null);
+        }
+
+        // If loan referencing non-existing clients throw 404
+        if(! isExistingClient(loan.getClientId().toString()))
+        {
+            throw new EntityNotFoundException("Client id " + loan.getClientId() + " does not exist.", null);
+        }
+
+        // Update values of matched loan with values of received request
+        Loan mergedLoan = this.loanMerger.merge(loanMatched, loan);
+
+        // Save updated loan
+        mergedLoan = this.loanRepository.save(mergedLoan);
+
+        // Return response
+        return this.loanToLoanResponseConverter.convert(mergedLoan);
+    }
+
+    @Override
+    public LoanResponse modifyLoan(LoanRequest loanRequest, Long id) {
+        Loan loan = this.loanRequestToLoanConverter.convert(loanRequest);
+
+        // If loan has null values or wrong values throw 400
+        if (
+                ! this.isValidSyntaxLoanForNulls(Objects.requireNonNull(loan))
+                        || ! this.isValidSyntaxLoanForZeroes(loan))
+        {
+            throw new BadParametersException("One or more parameters of the request are wrong", null);
+        }
+
+        // If loan does not exist throw 404
+        Loan loanMatched = loanRepository.findById(id);
+        if (loanMatched == null)
+        {
+            throw new EntityNotFoundException("Loan with id " + id.toString() + " does not exist", null);
+        }
+
+        // If loan referencing non-existing books throw 404
+        if (! isExistingBook(loan.getBookId().toString()))
+        {
+            throw new EntityNotFoundException("Book id " + loan.getBookId() + " does not exist.", null);
+        }
+
+        // If loan referencing non-existing clients throw 404
+        if(! isExistingClient(loan.getClientId().toString()))
+        {
+            throw new EntityNotFoundException("Client id " + loan.getClientId() + " does not exist.", null);
+        }
+
+        // Update values of matched loan with values of received request
+        Loan mergedLoan = this.loanMergerNonEmpty.merge(loanMatched, loan);
+
+        // Save updated loan
+        mergedLoan = this.loanRepository.save(mergedLoan);
+
+        // Return response
+        return this.loanToLoanResponseConverter.convert(mergedLoan);
+    }
+
+    @Override
+    public LoanResponse deleteLoan(String id) {
+        // If loan does not exist throw 404
+        Loan loanMatched = loanRepository.findById(Long.valueOf(id));
+        if (loanMatched == null)
+        {
+            throw new EntityNotFoundException("Loan with id " + id.toString() + " does not exist", null);
+        }
+
+        // Create search instance
+        Loan l = new Loan();
+        l.setId(Long.valueOf(id));
+
+        Loan loan = this.loanRepository.delete(l);
+        return this.loanToLoanResponseConverter.convert(loan);
+    }
+
+
+    // SPECIALIZATION
+
+    @Override
+    public List<LoanResponse> getLoansByClientId(Long clientId) {
+        List<Loan> loansList = loanRepository.findByClientId(clientId);
+        return loansList.stream().map((Loan l) -> this.loanToLoanResponseConverter.convert(l)).collect(Collectors.toList());
+    }
+
+    // PRIVATE METHODS
+
+    private boolean isExistingBook(String id) {
+        try {
+            ResponseEntity<BookResponse> book = buscadorClient.getBook(id);
+            Logger.global.info("MyText");
+            return book != null;
+        }
+        catch(Exception e) {
+            return false;
+        }
+    }
+
+    private boolean isExistingClient(String id) {
+        try {
+            ResponseEntity<ClientResponse> client = buscadorClient.getClient(id);
+            Logger.global.info("MyText");
+            return client != null;
+        }
+        catch(Exception e) {
+            return false;
+        }
+    }
+
+    private boolean isValidSyntaxLoanForNulls(Loan loan)
+    {
+        return loan.getBookId() != null
+                && loan.getClientId() != null
+                && loan.getLoanDate() != null
+                && loan.getReturnDate() != null
+                && loan.getDueDate() != null
+                && loan.getIsReturned() != null
+                && loan.getRenewalCount() != null;
+    }
+
+    private boolean isValidSyntaxLoanForZeroes(Loan loan)
+    {
+        return loan.getBookId() != 0
+                && loan.getClientId() != 0;
+    }
+}
diff --git a/src/main/resources/application.properties b/src/main/resources/application.properties
index c154b25..aa124c4 100644
--- a/src/main/resources/application.properties
+++ b/src/main/resources/application.properties
@@ -61,9 +61,10 @@ springdoc.swagger-ui.path=/swagger-ui.html
 # Configure application name for
 spring.application.name=operador
 # URL of the Eureka service
-eureka.client.serviceUrl.defaultZone=${EUREKA_URI:http://localhost:8761/eureka}
+eureka.client.serviceUrl.defaultZone=${EUREKA_URI:http://localhost:8762/eureka}
 # Use IP address
 eureka.instance.preferIpAddress=true
+eureka.client.register-with-eureka=false
 
 ###############
 ### LOGGING ###