Add client/service example using nav_msgs/srv/GetMap

[minggangw]

This PR adds comprehensive examples demonstrating client/service patterns using the nav_msgs/srv/GetMap service type, which is commonly used in robotics for retrieving occupancy grid map data. The examples complement the existing AddTwoInts service examples by showing how to work with more complex message types.

• Adds GetMap service server example that provides sample occupancy grid data
• Adds GetMap client example that requests and analyzes map data with visualization
• Updates documentation with detailed usage instructions and explanations

Fix: #1246

[Copilot]

Pull Request Overview

This PR adds comprehensive examples demonstrating client/service patterns using the nav_msgs/srv/GetMap service type, which is commonly used in robotics for retrieving occupancy grid map data. The examples complement the existing AddTwoInts service examples by showing how to work with more complex message types.

• Adds GetMap service server example that provides sample occupancy grid data
• Adds GetMap client example that requests and analyzes map data with visualization
• Updates documentation with detailed usage instructions and explanations

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
example/services/service/getmap-service-example.js	Service server that provides sample 10x10 occupancy grid map data with obstacles
example/services/client/getmap-client-example.js	Service client that requests map data and displays comprehensive analysis with ASCII visualization
example/services/README.md	Updated documentation with GetMap examples, usage instructions, and explanations of complex message types

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[Copilot]

The magic numbers 22, 33, 44 should be calculated using the formula y * mapWidth + x for clarity. For example: mapData[2 * mapWidth + 2] = 100; // obstacle at position (2,2)

Suggested change

	mapData[22] = 100; // obstacle at position (2,2)
	mapData[33] = 100; // obstacle at position (3,3)
	mapData[44] = 100; // obstacle at position (4,4)
	mapData[2 * mapWidth + 2] = 100; // obstacle at position (2,2)
	mapData[3 * mapWidth + 3] = 100; // obstacle at position (3,3)
	mapData[4 * mapWidth + 4] = 100; // obstacle at position (4,4)

[Copilot]

Date.now() is called twice which could result in inconsistent timestamps. Store the value in a variable: const now = Date.now(); sec: Math.floor(now / 1000), nanosec: (now % 1000) * 1000000

Suggested change

	const sampleMapResponse = {
	map: {
	header: {
	stamp: {
	sec: Math.floor(Date.now() / 1000),
	nanosec: (Date.now() % 1000) * 1000000,
	},
	frame_id: 'map',
	},
	info: {
	map_load_time: {
	sec: Math.floor(Date.now() / 1000),
	nanosec: (Date.now() % 1000) * 1000000,
	const now = Date.now();
	const sampleMapResponse = {
	map: {
	header: {
	stamp: {
	sec: Math.floor(now / 1000),
	nanosec: (now % 1000) * 1000000,
	},
	frame_id: 'map',
	},
	info: {
	map_load_time: {
	sec: Math.floor(now / 1000),
	nanosec: (now % 1000) * 1000000,

[Copilot]

Date.now() is called twice again, similar to the header timestamp. This should use the same timestamp value for consistency within the same response.

Suggested change

	const sampleMapResponse = {
	map: {
	header: {
	stamp: {
	sec: Math.floor(Date.now() / 1000),
	nanosec: (Date.now() % 1000) * 1000000,
	},
	frame_id: 'map',
	},
	info: {
	map_load_time: {
	sec: Math.floor(Date.now() / 1000),
	nanosec: (Date.now() % 1000) * 1000000,
	const now = Date.now();
	const sampleMapResponse = {
	map: {
	header: {
	stamp: {
	sec: Math.floor(now / 1000),
	nanosec: (now % 1000) * 1000000,
	},
	frame_id: 'map',
	},
	info: {
	map_load_time: {
	sec: Math.floor(now / 1000),
	nanosec: (now % 1000) * 1000000,

[coveralls]

coverage: 84.555%. remained the same
when pulling 2275d4e on minggangw:fix-1246
into d9a0440 on RobotWebTools:develop.